DOCUMENT RESUME

ED 059 043 SE 013 153

TITLE Fifty Years of Aeronautical Research.INSTITUTION National Aeronautics and Space Administration,

Washington, D.C.REPORT NO NAsA-EP-45PUB DATE 67NOTE 79p.

EDRS PRICE MF-$0.65 HC-$3.29DESCRIPTORS Aerospace Technology; *Aviation Technology; Research

Projects; Resource Materials; *Science History;*Technological Advancement

IDENTIFIERS NASA

ABSTRACT This booklet contains a detailed review of theaeronautical research conducted at Langley Research Center during the50 years after its construction in 1917 as the first researchlaboratory for the National Advisory Committee for Aeronautics. Theresearch is discussed in five parts, by decades: 1917-27, 1928-37,1938-471 1948-57, 1958-67. Photographs of aircraft are presentedthroughout the review. (PR)

U.S. DEPARTMENT OF HEALTH.EDUCATION & WELFAREOFFICE OF EDUCATION

THIS DOCUMENT HAS BEEN REPRO-DUCED EXACTLY AS RECEIVED FROMTHE PERSON OR ORGANIZATION ORIG-INATING IT POINTS OF VIEW OR OPIN-IONS STATED DO NOT NECESSARILYREPRESENT OFFICIAL OFFICE OF EDU-CATION POSITION OR POLICY

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Introduction

It is fifty years since the first symbolic shovels full of earth were liftedabove the soil of Langley Field to signal the start of construction ofthe first research laboratory for the National Advisory Committee forAeronautics.

Those shovels of Virginia ground symbolized more than the construc-tion of a research laboratory. They were tangible proof that this coun-try was determined to build an aeronautical research establishmentsecond to none in the world, aimed at regaining and then maintain-ing the lead in aeronautics which had been given to America byOrville and Wilbur Wright less than 14 years before.In md-1917, America had been at war for three months, in a conflictwhich was tO see the airplane grow from a scientific curiosity and asportsman's plaything to an effective weapon of war.But when the war broke out in 1914, the United States was last onthe list of world powers equipped with military aircraft, running apoor fifth behind France, Germany, Ruissia and Great Britain.

Not only the tangible evidence of aeronautical progress was lacking.The other powers had seen the value of aeronautical research labora-tories and facilities as early as 1866. In that year, the AeronauticalSociety of Great Britain was formed to stimulate research and ex-periment, and to interchange the information gained. H.2rbert Wenhamand Horatio Phillips, members of that Society, invt_nted wind tunnelssoon after 1870.FrarTe had major installations: Gustave Eiffel's pivately owned windtunnels at the foot of the Eiffel Tower and at Auteuil; the Army'saeronautical laboratory at Chalais-Meudon; and the Institut /.ero-technique de St.-Cyr. Germany had 11- boratories at Göttingen Uni-versity and at the technical colleges of Aachen and Berlin; the govern-ment operated a laboratory at Adlershof. and industry was well-equippedwith research facilities. Italy and Russia had aeronautical laboratorieslong before the United States took the step.National concern mounted as more and more scientifically prominentAmericans discoverr!d the woeful position of this country in aeronaut-tical research. In l!il 1, it was suggested that the Smithsonian Insti-tution, earlier the si. pporter of Samuel Pierpont Largley's pioneeringwork, be given respoasibility for an aeronautical labora;.ory. Objec-tions by both the W,-r and Navy Departments were influential inkilling the idea for the time being.But the Smithsonian pressed its case, and by the following year appearedto have met initial success. President William Howard Taft appointeda 19-man commission to consider the organization, scope and costsof such a laboratory, and to report its findings, along with itsrecommendations, to the Congress.An administrative oversight killed this approach; the appointmentshad been made solely by Presidential action, without the traditionaladvile and consent from the Senate. The legislation which wasproposed to authorize the laboratory failed to get unanimous consent.The Smithsonian decided to try it alone, and reopened Langley'slaboratory. One of the first tasks was a survey of major research andexperimental facilities abroad.The report which came out of that survey showed clearly the dangerousgap between the state of aeronautical technology in Europe andin the United States. Once again, the Smithsonian decided to approachthe Congress, and on February 1, 1915, delivered to the Speakerof the House of Representatives a statement which said, in part:

"A National Advisory Committee for Aeronautics cannot fail to beof inestimable service in the development of thc art of aviation inAmerica ... The aeronautical committee should advise in relationto the work of the government i. aeronautics and the coordination ofthe activities of governmental and private laboratories, in which ques-tions concerned with the study of the problems of aeronautics canbe experimentally investigated."That statement became a joint resohition of Congress and was added

as a rider to thc Naval Appropriations Act approved March 3, 1915.

The Act established an Advisory Committee for Aeronautics (Theword "National" was to be added later at the first Committee meetingdetailed its organization, apportioned its membership, and describedits general task in words which need no improvement today:

". . . it shall be the duty of the Advisory Committee for Aeronauticsto supervise and direct the scientific study of the problems of flight,with a view to their practical solution, and to determine the problemswhich should be experimentally attacked, and to discuss their solu-tion and their application to practical questions. In the event of alaboratory or laboratories, either in whole or in part. being plac,edunder the direction of the committee, the committee mai direct andconduct researrh and experiment in aeronautics in such laboratory orlaboratories."The first Committee appointments were made by President WoodrewWilson on April 2, 1915, and the first full Committee meeting mIsheld April 23.Among the early projccts completed by the Executive Committee ofNACA was a facilities survey of industry, government and universi-

ties. Ot.t of that work, NACA concluded that 't would require both alaboratory and a flight-test facility, thc former for model work andexperiment, and the latter to work with full-scale pi )blems. Withforesight the Committee recegnized that building and equipping thesefacilities ought to bc a gradual and continuing )rocess, so that thclaboratory could stay abreast of developments in technology.

During 1916, NACA called a meeting of aircraft and engine manu-facturers to dis,:uss thc problems and progress ir aii.plane engine designand development. That meeting was the first of many to come, an,"it initiated thc close vvorking relationships between the governmentlaboratory and private industry which have existed ever since.

*Meantime, thc Secretary of War has been told hy Congre-s to surveyavailable military reservations to find one suitable for an aeronauticalexperimental station, or to recommend a new site, if no existing

site were suitable. The Army appointed an officer board which selecteda site a few miles north of Hampton, Virginia.It fulfilled the requirements of the search: It was flat land, frontingon water so that test flights could be made over both land and water.It was cast of the Mississippi and south of the Mason-Dixon line,where weather was generally good for flying. It was no farther than12 hours by train from Washington, D. C. It was not so cloc to anunprotected coastal area as to be subject to attack or possible capturein thL event of war.A special NACA subcommittee went through a similar search for its

own experimental station site, and concluded that the Army's choice

was a wise one. The subconnnittee recommended that the Army

buy thc site north of Hampton as a tcst arca for joint Army, Navy

and NACA experin:, nts.That site was to become Langley Field, named after Samuel PicrpontLangley. NACA (which in 1958 became thc nucleus of the NationalAeronautics and Space Administration) would build its first testcent?c there, but neither the Army nor the Navy would use it forexi Minental work. The Army would establish its tcst arca at McCook

would move its experimental work acroK the water to Norfolk, Virginia.Field, near Dayton, Ohio; thc Navy, oriented toward tcsts of seaplanes,

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1917-1927Langley Research Center, born during the firstWorld War, saw the shaping of the frameworkof decades to come during its first ten years oflife.The war had introduced day and night bombing.It had spurred the development of bomb sights,automatic pilots, radio communication and navi-gation aids, self-sealing fuel tanks and pilotlessaircraft.Within three months after the Armistice, com-mercial aviation started in Germany whenDeutsche Luftreederei began its passenger-carrying service. That year also had seen thefirst daily commercial air service started, withflights between London and Paris. The firstinternational passenger flights from the U. S.followed in 1920; by 1925, regular air freightservice had been established between Chicagoand Detroit. The new transport industry becurnesubject to its first regulatory legislation, the AirCommerce Act, signed into law in 1926 byPresident Calvin Coolidge.

Record flights by the score showed the way towardthe future routine accomplishments of civil andmilitary aviation. The Atlantic was crossed firstby a U. S. Navy Curtiss NC-4 flying boat,and then, non-stop, by Britain's Capt. johnAlcock and Lt. Arthur W. Brown in 1919.Four years later, the first non-stop transcontinen-tal crossing of the United States by air wasmade by Lts. 0. G. Kelly and j. A. Macready.

In 1924, two of four Army Douglas amphibious

biplanes completed a round-the-worldflight,another first in aviation history. During the26,350-mile flight, they fiew the first trans-Pacific crossing and the first westbound North

Atlantic crossing.

But the most-remembered achievement of the

post-war years was the solo crossing of the

Atlantic by Charles A. Lindbergh. Hishistory-making flight drew world-wide attention

to the potential of the airplane, and gave animpetus to aviation that no other singlefeatsince the Wright brothers' first flight ever has

matched.Other developments during that first decade pointed

the way toward the future of aviation. A CurtissIN-4 was remotely controlled in the air fromanother IN-4; the Sperry gyro-stabilized auto-pilot was successfully tested. Inaccessible partsof Alaska were mapped from the air; a Hawaiianforest was planted from the air; cloud-seedingexperiments began.

Target battleships were sunk by bombing; piped,midair refueling was demonstrated. An all-metal,smooth-surfaced wing was built in Germany byRohrbach, L',e progenitor of the stressed-skinstructures which are standard today.And in widely separated parts of the world, Dr.Robert H. Goddard successfully developed andfired liquid-fuelled rocket motors, the GermanSociety for Space Travel (Verein fuer Raum-sch(ffahrt) was organized, and the Russiangovernment established a Central Committee for

the Study of Rocket Propulsion.

The problems facing the airplane designer in ihe

early post-war years were difficult. The struttedand wire-braced biplane had high drag, and alow lift-drag ratio. It had poor propeller per-formance, and an engineor enginesof lowhorsepower and doubtful reliability.

Added to this were the complete lack of anymeans to control the landing speed and the approach

angle, the lack of knowledge of gusts and maneu-

vering loads, and stability and handling charac-

teristics that varied from acceptable to dangerous.

It is remarkable that any aviation progresswas made.But it was. The list of technological innovations

of this decade is impressive.It includes the development of a reliable, air-cooled engine; cantilevered design; the use ofmetal in structures; the concept of tri-motored

aircraft; the experimental use of superchargers;the trend to the monoplane; and the development

of limited blind flying equipment.This was the form of Me first decade at Langley.

It was a ten-year period of startling growth for

the airplane, out of its role as a winged weapon

of war and into new jobs for the military and

a wide range of commercial services.

But the growth had been more accidental thanplanned. Designers worked with a paucity of

data and filled the gaps with their own experi-

ence or the experience of others. It was a decade

of empirical development, of luckyand, too

often, unluckysolutions to the manifold

problems of airplane design.

It would be the aim of NACA's new aeronauti-

cal research laboratory at Langley Field to

reduce the element of luck in airplane design, to

replace it with a body of carefully developed

scientific data, and to point the way to improved

airplane design concepts.

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1. One of two CurtissJN-4H "Jenny" trainersbefore speed tests, 1919.

2. Sperry M-1 Messengerwas evaluated in flight

and in the propellerresearch tunnel.

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In the heat of July 1917, excavation beganat Langley Field for the first researchlaboratory to be built for the NationalAdvisory Committee for Aeronautics.Langley had been authorized as the site forNACA's experimental air station just themonth before, and a contract had beenlet for construction to the J. G. WhiteEngineering Corp., of New York Uty.Estimated cost of the laboratory was$80,900.By November 1917, after surveys of exist-ing industry and airfields to determine thestate of aviation in the United States,NACA authorized the preparation of plansand specifications for its first wind tunnel.It was to be like the pioneering wind tunneldeveloped by Gustave Eiffel, with a testsection about five fet t in diameter and aninsert which could be used to reduce theworking area to a cross-section with a two-and-one-half foot diameter.Work began on the tunnel in the spring of1919, and it was ready for operation oneyear later.By then, NACA had proposed a nationalaviation policy, and among its recommen--dations was one that research be expandedat the Langley laboratory. NACA alsooffered the use of its experienced personneland its new facilities to universities andindustry in order to foster aeronauticalresearch and experimental work outside ofgovernment laboratories.

The new wind tunnel was operated for thefirst time at the formal dedication of theLangley Memorial Aeronautical Labora-tory, now the Langley Research Center,on June 11, 1920. Visitors to the lab saw asmall brick-and-concrete building, fromwhich sprouted two bell-shaped surfacesopen at the ends. This was the wind tunneland the test bAlding.

The test building was about ten by fourteenfeet in floor dimensions, and it stood about23 feet high. Through the center of thebuilding ran the cylindrical test section inwhich test models were suspended on wires.Below the test section were chairs whereengineers sat and read the balance arms ofordinary wcigh scales which had beenmodified to measure the loads on the modelduring the test.

The tunnel could produce a test section'speed as high as 120 mph,, believed to bethe fastest useful test speed then attainablein the world. Further, it apparently hadexcellent flow characteristics, compared toits contemporaries, and what were termed"satisfactory means for measuring the forceson models at the highest velocities."

Within six months or so, the CommitteeFt

ti authorized construction of a second windtunnel, a compressed-air unit designed tocorrect for the scale effect which produceddifferences between model and full-scaledata. Plans were approved one year laterand construction was authorized.The tunnel was designed to run at pres-

t- sures as high as 20 atmospheres (about 300psi.), and the test section was to have a

t5, five-foot diameter.tThe compressed-air tunnel, later to bedesignated the variable-density tunnel, wasoperated first at the annual meeting of thefull NAGA Committee on October 19,1922. Incidentally, there was not enoughelectrical power available at Langley to runboth it and Tunnel No. 1 concurrently.The Committee must have been impressedwith the growth and stature of the LangleyLaboratory at the time of the 1922 meet-ing. It now was made up of six units:The research laboratory building, whichincluded administrative and drafting offices,machine and woodworking shops, andphotographic and instrumentation labs;two aerodynamic laboratories, each con-taining a wind tunnel; two engine dyna-mometer laboratories, one of which was ina permanent building while the other wasin a converted hangar; and an airplanehangar on the flying field.

Test equipment included an automaticbalance and a high-pressure manometerfor the variable-density tunnel, and a spe-cial wire balance, for the first wind tunnel,

suitable for making tests of biplane andtriplane models.These test techniques and facilities wereaimed at measurements of the aerodynamiccharacteristics of existing aircraft andtheir components, to devise concepts toimprove those characteristics.But wind tunnels weren't the only testtechniques available to the Langley engi-neers. Within the second year of Langley'sexistence, work had started on the develop-ment of instruments for flight-test work,so that measurements could be made cnfull-scale airplanes and correlated withdata obtained from models in wind tunnels.That first instrumentation program calledfor ways to measure engine torque andrpm., propeller thrust, airplane speed andangle of attack. Knowledge of these param-eters of a full-scale airplane would bothsupplement and complement data takenduring wind tunnel tests.This two-pronged approach to the problemsof aeronauticsby model tests and by full-scale flight testsestablished the interde-pendence of these two test disciplines earlyat Langley. Emphasis on that dual ap-proach has been strong ever since, and isone of the foundation stones of Langleyresearch policy today.By mid-1919, with construction of the firstwind tunnel underway at Langley, re-search was authorized for the first NACAflight tests with full-scale airplanes. Thepurpose of the tests was to compare in-flight data with wind tunnel data for the

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6 same aircraft to show the degree of cor-relation, and to determine, if it could bedone, a way to extrapolate wind tunneltests to full-scale results.The first provam used two Curtiss JN-4H"Jenny" trainer biplanes in a detailed in-vestigation of airplane lift and drag. Itwas the forerunner of a myriad of detailedinvestigations that would later lead to thedevelopment of a series of research aircraftto explore the unknowns of subsonic andsupersonic flight.There was a second important result ofthat first program with the Jennies. TheNACA Technical Report which describedthe tests also nottx1 that there was a needto develop a special type of research pilot.This was perhaps the first time that therole of the engineering test pilot had beenrecognized and described.The faithful Jennies served in a variety oftests during the years. They pioneered in-flight investigations of pressure distributionso that designers could calculate the airloads acting on the wings and tail of theaircraft. In the first program, begun in1920, NACA technicians installed 110pressure orifices in the horizontal tail ofthe wood-and-fabric Jenny, hooked to abattery of liquid-in-glass manometers whichcould be photographed in flight.Early in January 1921, research was begunto compare the characteristics of wings inmodel tests and in full-scale flight tests, sothat designers could be furnished with com-plete and accurate data on which to basetheir performance estimates.

During that same year, new instrumentswere developed and tested in flight tomeasure control position and stick forcesexerted by the pilot. This was done tounderstand and improve handling charac-teristics, and thus increase flight safety. Re-fined and miniaturized instruments usedfor the same basic purposes find continuedemployment today in the tests of high-speed jet aircraft or rocket-propelledresearch vehicles.Pressure distribution investigations becamea major portion of the flight-test work atLangley. From the measurements of loadsin steady-state flight, the work was ex-panded to study the effects of acceleratedflight or maneuvers, because at that time,there was virtually no data available todesigners on the distribution of the loadon the wing of the airplane in acceleratedflight.

Later work extended the pressure-distribu-tion measurements to the nose of a non-rigid airship, first under steady flight con-ditions, and then during maneuvers overa range of airspeeds and atmosphericconditions.Five airplanes shouldered the load of flighttest work during 1921. Three of them werethe Jennies, Curtiss JN-4H types. Theyshared the flying field with the Lewis &Vought VE-7 and a Thomas-Morse MB-3.Together, the Jennies logged 110 hr. offlight time in 260 flights during 1921.More than half of the flight time was spentin data collection.Other pacemaking research began in 1922,

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when the first systematic series of takeoffand landing performance measurementswas made at Langley. During that year,the Navy Bureau of Aeronautics askedNACA to undertake a comparative studyof the stability, controllability and maneu-verability of four airplanes: The VE-7, theMB-3, a British SE-5A, one of the mostwidely used pursuit aircraft in WorldWar 1, and the famous Fokker D-VII, themainstay of the German Imperial AirService during the same conflict.The SE-5 and a De Havilland DH-4 hadjoined the Langley flight test fleet in 1922,to raise the number to seven aircraft. Inaddition, four c turcraft were beingrefitted for test programs or support work:The Fokker D-VII, a Nieuport 23, aS.P.A.D. VII, and a De Havilland 9.

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Again the Jenny was used as a test vehiclein 1922 in an extensive investigation ofmaneuverability. The aim was to find asatisfactory definition of the word, in anaerodynamic sense, and to establish waysof measuring it. Before this time, maneu-verability was a subjective judgment by apilot, full of personal likes and dislikes.The same airplane could be judged lighton the controls and maneuverable by amuscular pilot, and heavy on the controlsand sluggish by a lesser man.

What was needed was some way of reduc-ing subjectivity to objectivity, and NACApilots and engineers at Langley set aboutfinding that way.They instrumented the Jenny to measureits angular velocity following a motion ofits controls, as a first approach to definingwhat maneuverability was.Like so much of Langley's pioneering work,this early study of maneuverability grewinto the extensive flight research workdone today on the handling qualities ofaircraft. The basic approach laid downthen is valid now.The calibre of the flight-test work beingdone at Langley began to attract attentionfrom the military services. In 1923, theNavy's Bureau of Aeronautics came toLangley with a request that the Laboratoryrun a series of flight tests in the low-speedregime on its TS aircraft, a scout aircraftdeveloped by Curtiss. The Navy was par-ticularly interested in accurate determina-tion of the stalling speed, and the takeoffand landing speeds.The Army Air Service also was concernedwith similar questions. The service askedNACA in 1924 to study the acceleration,control position, angle of attack, groundrun and airspeed during the takeoff andlanding of most of the airplanes then in

1. Flight research, 1924: 7

JN-4H, Fokker D-VH,MB-3, DH-4 and SperryM-/.2. Thomas-Morse MB-3joined the Langley testfleet in 1921.

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service with the AAS. The list included theCurtiss JN-6H; the Lewis & Vought VE-7;the De Havilland DH-4B, the FokkerXCO-4, the prototype of the C.IV two-place biplanes then in service with severalcountries; the SE-5A; the S.P.A.D. VII;the MB-3; the Martin MB-2, a biplanebomber; and thc Sperry Messenger.By then, Langley's flight line sported 11test aircraft; during 1924 they logged 918flights for a total of 297 hr. of flight time.The same year, the Army requested a flightresearch investigation of the pressure dis-tribution over the wing of a Lewis &Vought VE-7 tandem trainer. The servicetransferred one of the aircraft to Langleyfor the program.The VE-7 soldiered on through other workafter that test was completed, including alandmark program using seven differentpropeller designs, aimed at determiningthe effects of different propeller design onperformance.Those tests, along with tests with a seriesof six interchangeable wings, each with adifferent airfoil section, on a Sperry Mes-senger biplane, became the first of manyNAGA comparative tests where a system-atic approach was used to develop a betterinstallation or to design a better component.Sophistication had come both to flight test-ing and wind-tunnel testing. By mid-1924,NACA was able to make complete pres-sure distribution surveys, either in thewind tunnel or in flight, in one day ofwork. Formerly, such tests had required aseries of runs over a time period as long astwo months.

Later thc same year, NACA reported afurther refinement in flight testing tech-niques. Recording instruments had beendeveloped, the Committee said, to make acontinuous record of pressure distribution,accelerations, and other parameters durin;flight tests of aircraft.During 1925, the flight-test program con-tinued to grow, and there were 19 airr,rririn various phases of test work at Largley.They made a total of 626 flights during theyear, and logged 245 hr. of flight time.An engine research laboratory had beenstarted and a dynamometer, to measureoutput and other performance data on air-craft engines, had been installed in 1919.Since then, a second had been added.Both were kept busy, and so were thepowerplant engineers. Early work on super-chargers, investigated at Langley in 1924,led to consideration of supercharging toboost engine power for high-altitudebombers, and to obtain a good rate ofclimb for interceptors. This engine researchlaboratory lacer became the nucleus of theLewis Research Center.One specific study was made to determinethe adaptability of supercharging to anair-cooled engine and its effect on theflight performance of the engine.

Two more pioneering programs were be-gun at Langley in 1925. The first of thesewas an attempt to standardize wind-tunnelresults, a necessary preliminary to com-parison of data taken from two differentwind-tunnel installations. NACA engineersdeveloped a series of circular discs whichwere tested in the Langley tunnel, and then

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sent o other wind tunnels for testing underthe same conditions. The results, whencompared, offered a way of checking theresults of one wind tunnel against another.Second of these early programs which ledthe way was the beginning of the measure-ment of landing loads, even today a majoreffort at Langley laboratory. But at thattime, the loads were to be measured onseaplane floats, so that the specificationsfor the design of float bracing could beimproved.On May 24, 1926, NACA held its firstjoint conference with representatives of theaircraft manufacturers and operators atLangley. It was the first of what was tobecome a recurring event and a greatNACA tradition: the inspection tour. Butit went further; it provided the guests withan opportunity to criticize current researchand to suggest new avenues they believedpromising.The second of these conferences, held thefollowing year, was expanded to includerepresentatives of educational institutionsthat taught aeronautical engineering, andof trade journals that played such animportant part in the dissemination ofaeronautical information.This interchange of information betweenindustry and NACA, always one of themajor factors in directing the course of theCommittee's research, has been maintainedover the years since the first formal jointconference in 1926.

By that time, the outstanding work of theLangley Laboratory had also been recog-liized by foreign institutions. Typical ofthat recognition was a request from theAeronautical Research Committee of GreatBritain, which asked Langley to run aseries of wind-tunnel tests on three airfoilsections, incorporated in wing designs onthree different aircraft models. The resultswere to be used for comparison with wind-tunnel and full-scale flight results previouslyobtained in England.One of the more significant developmentsin aeronautical research to grow outof the Langley laboratories had its begin-ning in a letter sent from the Navy's Bureauof Aeronautics in 1926. The Navy hadbeen convinced that the air-cooled enginewas a more practical solution to its power-plant problems than the liquid-cooledpowerplants favored by the Army. ButNavy engineers were well aware that air-cooled installations had more drag andwasted more power in cooling the enginethan seemed necessary. The engineers be-lieved there was some way to put a stream-lined cowling around the engine to reduce

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1. Ford truck, Huckstarter, and Lewis &Vought VE-7, around1924.2. War booty, thisGerman Fokker D-VIIwas tested at Langleyin 1922.

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10 its drag and improve its cooling perform-ance, and they asked Langley to investigatethe possibilities.A similar request came out of the secondindustry-NACA meeting. Industry engi-neers, obviously up against the same prob-lem the Navy faced, turned to NACA forhelp. They asked that the effect of thefuselage shape on cooling and cowling alsobe taken into account, in addition to theeffects produced by whatever optimumcowling shape the laboratory was able todevise.Model work in the one remaining windtunnelthe variable-density tunnel hadbeen badly damaged by fire in August 1927and was out of action for two yearswasn't the answer. The models were small,and were tested without propellers. Flighttest would be too costly, and too time-consuming, but it looked like the only waypossible at the time.The final answer was to come from thepropeller research tunnel, a brand-new pieceof equipment authorized two years beforeand scheduled to start operation at the endof 1927. Originally planned to be able totest full-scale propellers under simulatedflight conditions, the tunnel also was tobe used for the testing of full-scale fuselages

or tail surfaces, or of large model wings.With its 20-ft. diameter test section, and itstop wind velocity of 110 mph., it was notonly the largest wind tunnel in the world,but also the first in which the major com-ponents of a full-sized airplane could betested.

With the availability of this new researchtool, Langley had come of age. Its firstten years of life had been devoted largelyto exploring and identifying the problemsof aeronautics.

The years had been used to develop theorganization, to build facilities, to surveythe industry and the operators of aircraftto determine what kinds of problems neededsolutions.

Along the way, problems were solved, andmajor contributions were made to the air-craft designs of the day. But the majorcontributions of Langley during its firstten years of life were made to itself and tothe National Advisory Committee forAeronautics, to their functioning andgrowth, to give them the ability to under-stand the problems of flight and to beready to find solutions to them as tt e needfor those solutions grew more and morepressing.

Sperry M-1 Messen-ger was first full-scaleairplane tested and one

of first test programs inthe propeter research

tunnel, in mid-1927.

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r 1928-1937The second decade of work at the LangleyMemorial Aeronautical Laboratory began onthe upsurge of a new wave of popular interestin aviation. Lindbergh's historical crossing ofthe Atlantic had touched the imagination of theworld, and had converted skeptics into believers.

This decade would produce a revolutionarychange in the appearance and performance ofairplanes, firmly establishing their position inthe growing transportation networks of the worldand guaranteeing their future predominance inthat field.

In commercial aviation, Transcontinental &Western Air inaugurated the first coast-to-coastthrough air service in 1930, between New Yorkand Los Angeles. The Boeing 247 and theDouglas DC-1, progenitors of long lines oftransports to come and of years of commercialrivalry between the companies, made their first

flights during 1933. The following year, Douglasstarted work on the DC-3, the ,plane that wasto revolutionize air transport. It firstflew in 1934.

That same year, Pan American started surveyflights withflying boats across the Pacific andfollowed with the start of air mail service fromSan Francisco to Manila. In 1936, the airlinecarried the first passengers on its new trans-Pacific route. In 1937, Pan Am and the Britishcarrier, Imperial Airways, made survey flightsacross the Atlantic, and Pan Am started the firstair mail service between the United States andNew Zealand.

During the decade, Boeing's Model 299, theprototype of its B-17 "Flying Fortress" series,made its first flight (1935). In Britain, the proto-type Hawker "Hurricane" flew for the first time,and the first report on radio detection and rang-ing (radar) was presented to the British AirDefence Research Committee.

Three wars, which led to an increased appre-ciation of airpower, erupted during this period.Japan began its operations against China in1931; Itdy declared war on Abyssinia in 1935;the Spanish Civil War began in 1936.The tragic Spanish conflict drew other nationsto the fighting within Spain's borders, and gavethem the opportunity to test and develop newweapons and concepts. Guernica, the seat of theBasque government, was bombed and devastatedby German aircraft in a demonstration of thingsto come.

The decade saw the death of the dirigible fol-lowing a series of tragic accidents to the BritishR-101, the U. S. Navy's Akron and Macon,and the German Hindenburg.

Some of the most radical developments of the tenyears took place in jet propulsion. The year 1928saw the first rocket-powered glider flight made inGermany, and the publication of a fundamentalpaper on jet propulsion by Frank Whittle. Nineyears later, his first engine was run. The Rus-sians published the first volume of a nine-volumeencyclopedia on interplanetary flight that year.

In 1929, the first known use of jet-assisted take-off was successfully demonstrated in Germany.

The following year, the German Verein fuerRaumschijahrt established a test site in Berlin,and the German Army Ordnance Corps organizedits rocket weapon program and moved it into atest station at Kummersdorf.

Static tests of a Heinkel He-112, converted tobe flown with an auxiliary rocket engine, weremade in mid-1935, and the airplane made itsfirst successful test flight early in 1937. It wasthe forerunner of later German developments inrocket-powered fighters.

In 1937, German Army Ordnance opened itsrocket development station at Peenemunde. InRussia, three rocket test centers were establishednear Moscow, Leningrad, and Kazan.The biplane was the standard design whenNACA's Langley Memorial Aeronautical Lab-oratory started its second decade of life. TheArmy Air Corps' newest bomber was the Curtiss"Condor", a twin-engined biplane with fixedlanding gear, strut bracing, open cockpit and abiplane tail assembly. Its hottest fighter wasanother Curtiss product, the P-1 series, progeni-tor of a long line of Curtiss "Hawks." It toowas a biplane, with strut bracing, fixed landinggear, and a liquid-cooled engine.

The commercial airways were served by the tri-motored monoplane Fords, an all-metal high-winged design, the Boeing 80 biplanes, also tri-motored, and various single-engined designs suchas the Fokker Universal.

In most of the commercial and military designs,the basic airplane was a strut-braced and wire-braced biplane, built of wood or steel tubing, andcovered withhbric. Its landing gear was fixed;its engine,if hircooled, was uncowled. The pro-peller was a fixed-pitch type. The monoplane 18

13

14

1. Army Curtiss AT-5Awas first airplane fitted

with NACA cowling:1928.

2. Langley metal work-ers fabricated NACA

cowlings for early testinstallations.

19

design had been established, but in most in-stances as a strut-braced layout. Its designerswere unsure of the problems offlutter and aero-elasticity.

By the end of this second decade, the biplane wasalmost as dead as the dodo. Military and com-mercial craft were internally braced, unstruttedmonoplanes, with sleekly cowled engines, retrac-tible landing gear, and wing flaps. The designrevolution of the early 1930s had been sparked bydevelopments at Langley.

The propeller research tunnel, which beganoperating in 1927 at the end of Langley'sfirst decade, began to pay off its investmentin the earliest years of the second decade.For the first time, an aeronautical labora-tory had a research wind tunnel big enough,and versatile enough, to test full-size air-craft components. There was an additionalbenefit; the scale of testing was physicallylarge enough so that tiny components,which would have been nearly invisible onthe small wind tunnel models previouslyused, could be evaluated. This was to makepossible a whole new world of test studiesthat would result in detailed refinement ofmany aircraft to come.The first program in the propeller researchtunnel was directed toward the problemsstated by the Navy and industry earlier:The reduction in drag and improvement incooling efficiency of an air-cooled engine.The result, after systematic wind tunneltesting, was the construction and installa-tion of an NACA-designed cowling on aCurtiss AT-5A advance trainer of the ArmyAir Corps. The NACA Annual Report for1928 said that ". .. the maximum speedwas increased from 118 to 137 mph. Thisis equivalent to providing approximately83 additional horsepower without addi-

-..."1L

tional weight or cost of engine, fuel con-sumption, or weight of structure. Thissingle contribution will repay the cost ofthe Propeller Research Tunnel manytimes."The Wright R790-1 air-cooled engine whichpowered the AT-5A was rated at only 220hp. The additional equivalent of 83 hp.was a staggering boost in available enginepower, or an equally staggering reductionin engine drag, depending on the viewpointof the designer.NACA received the 1929 Collier Trophyaward for the development of the cowling.The Trophy, an annual award for thegreatest achievement in aviation in theUnited States, was presented in 1930 toDr. Joseph S. Ames, then NACA Chairman,by President Herbert Hoover.The design revolution had begun. TheNACA cowling was to become the standardenclosure for air-cooled radials, and wasto be continually revised and improved inthe future. The dramatic reduction in cool-ing drag produced by the cowling leddesigners to ask for, and NACA to lookfor, other areas where drag could be reducedsubstantially.One obvious source of drag was the fixedlanding gear, long recognized as a primeproducer of built-in headwinds. The SperryMessenger was tested in the propeller re-search tunnel, and its fixed landing gearwas found to account for nearly 40 percentof the total airplane drag. These measure-ments were the first to pinpoint the exactamount of drag caused by the landing gear,and the first to show the performancepenalty incurred by not retracting thegear.Still working in the interests of drag re-duction, NACA engineers looked at a tri-

4

motored Fokker transport powered byWright J-5 Whirlwind powerplants. Cowl-ing these engines, they reasoned, shouldmake a substantial improvement in theperformance of the airplane. But it didn't,and they began to wonder why.The wondering led to the belief that maybethe awkward powerplant installation hadsomething to do with it. The standarddesign of the period was to support theengines above or below the wing on astrutted structure, whose dimensions weredetermined by eye rather than by anyaerodynamic considerations.Studies in the propeller research tunnelsoon showed there was an optimum posi-tion for engine nacelles, and it wasn'tabove or below the wing. The optimumwas for the nacelle to be faired into theleading edge of the wing; the improvementagain was marked.Meantime, NACA had been conductingsystematic investigations of propellers, ofairfcd sections, of high-lift devices, of inter-ference drag between fuselage and wing,or fuselage and tail. Wing fillets were de-veloped, and reported in a 1928 TechnicalNote. Even the drag of small fittings, suchas a protruding gasoline tank filler cap,could be measured and its effect onperformance assessed.The quiet revolution was well underway.For the first time, designers could build a"clean" airplane, could estimate its drag

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and performance more accurately, andcould understand the possibility of a smallchange causing a major increment inperformance.The availability of the NACA cowling,propellers of increased efficiency, moreefficient airfoils, wing fillets, and knowledgeof the mechanism of drag led directly tothe change in design from the struttedbiplane to the sleek monoplane.No longer could a designer argue that itwasn't worth the weight and complexityto retract the landing gear for those fewmiles per hour. The aerodynamicists couldtell him that those miles per hour weren'tfew, and that retracting the gear couldmean the difference between winning andlosing a contract.Even before the NACA cowling had beencompletely developed in the propeller re-search tunnel, NACA realized that a full-scale tunnel would be a necessity. Airplaneswould be bigger than the 20-ft. throat testsection of the PRT, and the work load offull-scale airplane testing was bound toincrease as soon as industry and the mili-tary realized the advantages of such testwork.The need for the full-scale tunnel was firstoutlined in a letter from Dr. Ames to theDirector of the Bureau of the Budget.Construction began in January, 1930, andthe tunnel was officially dedicated at thesixth annual conference in May, 1931.

"

I

or .4,1

1 5

16

1111011.-_

1. Langley's variable-density tunnel, damaged

by fire in 1927, wasphotographed in March,

1929, when tests beganagain.

2. Military aircraft of thedecade, shown during

tests in the full-scaletunnel at Langley:

Boeing PW-9 of 1925.

3. Vought 03U-1,in 1931 the first com-

plete airplane to betested in the full-scale

tunnel.

4 . Douglas XO-31 of1930.

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21

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Other research facilities at Langley grewout of specific needs. Some research workhad been done in 1927 on the preventionof aircraft icing by thermal systems, butthe study had been completed withoutfurther action. Early in 1928, the AssistantSecretary of Commerce for Aeronauticscalled a conference of military and govern-ment agencies, including NACA, to studythe causes and prevention of ice formationon aircraft. A few days earlier, the Navy'sBureau of Aeronautics, frequently a pioneerin defining a problem area, had askedNACA to determine the conditions underwhich ice forms on an aircraft, and todevelop some means of prevention.The result was NACA's first refrigeratedwind tunnel, which began operations dur-ing 1928. Its aim was to study ice forma-tion and prevention on wings and propel-lers of aircraft, and its tests pointed theway toward the successful developmentof schemes to prevent, or remove, iceaccretions.These studies grew into a major effort thatlater won another Collier Trophy for anNACA scientist. Lewis A. Rodert, who

began his NACA career at Langley, wonthe 1946 trophy "for his pioneering re-search and guidance in the developmentand practical application of a thermalice-prevention system for aircraft."Rodert conducted most of his basic researchfrom 1936 to 1940, during which time hewas in the Flight Research Division ofLangley. He transferred to the Ames labor-atory in 1940, and was Chief of FlightResearch at the Lewis laboratory when hewon the Collier Trophy.In 1928, the Army's experimental flight-test facility at Wright Field had begun aseries of tests to determine the spin charac-teristics of aircraft. Two years later, Langleyhad started to operate a free-spin windtunnel, in which models could be spun ina manner simulating the dynamics of full-scale, free flight.This led to the construction of a largerspin tunnel, with a 15-foot throat and ad-justable airflow velocity so that the modelcould be held at one position in the throatand observed visually from outside thetunnel.The success of this type of wind tunnel ledNACA directly to the more complex free-flight tunnel, a major research tool whichhas given birth to a range of test techniquesused with models of today's aircraft.The first of Langley's hydrodynamics testtanks was completed in 1931, to serve theresearch needs of the seaplane and am-phibious airplane designers. The windtunnels would provide aerodynamic be-havior of the aircraft; the test tanks wouldanalyze the behavior of models on thewater in an analogous manner.

The tank was 2,000 ft. long, although laterextended to 2,900 ft., and was used pri-marily to determine the performance char-acteristics of hull shapes. By towing themodel hull through the water from a stand-ing start to a simulated takeoff speed,Langley scientists could determine thehydrodynamic performance of the hull andsuggest changes or improvements in thebasic design.

The tow tank was used also for systematicdevelopment of families of hull shapes. Inlater years, a second tank, 1,800 ft. long,was built. In that tank, simulated forcedlandings on water would be done withlandplane models, and still later the Mer-cury, Gemini and Apollo water-landingtechniques would be checked out usingthe same tank.

At the time when airplanes were routinelylogging speeds of less wan 200 mph., NACAwas looking ahead to the future where

22

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speeds up to 500 mph. might be possible.Late in 1933, NACA outlined its needs fora 500-mph. wind tunnel, called then the"full-speed" tunnel, and estimated its costat under a half million dollars in a letterto the Federal Emergency Administrationof Public Works. Construction of the tun-nel was completed in March, 1936, and itbegan operations in September that year.Its test section had an eight-foot diameter,enough to investigate large models of air-craft and some full-scale components.The eight-foot tunnel was to become apioneering tunnel in high-speed aero-dynamic research in this country, and wasto be the foundation of the future structureof Langley's brilliant work in the highsubsonic speed range and on into themysteries of the transonic region.Other pioneering facilities were designedand started during this second decade.The 19-foot pressure tunnel constructioncontract was awarded early in 1937, andlate that year the first low-turbulence windtunnel entered construction.The 19-ft. tunnel was a leader in propellerresearch, because it could test a full-scalepropeller in a close approximation of itsoperating range.The low-turbulence tunnel was to becomethe source of the NACA low-drag (laminarflow) airfoil.Still closely coordinated with the aero-dynamic work at Langley was the job offlight research. A new kind of aircraftcalled an autogyro had been flown in theUnited States for the first time in 1928.This was the first departure from the fixedwings of the basic Wright brothers design,a radical approach providing lift by usingrotating wings.During 1931, Langley bought a PitcairnPCA-2 autogyro and started its work onrotary-wing aircraft. The PCA-2 was in-strumented and test-fkwn. Its rotor wastested in the full-scale wind tunnel forcorrelation between tunnel and flight tests,

Wit*4tiZIk

and a model of its rotor was tested in thepropeller research tunnel to determinescale effects. A camera was mounted on thehub of the rotor to photograph the bladebehavior during flight.The flight tests of the PCA-2 included somemeasurements during severe maneuvers,with results still applicable to the fast-moving helicopters of today. That particu-lar autogyro had a fixed wing surface tocarry some of the weight of the aircraft innormal forward flight. The flight testsmade at Langley included some work inwhich the incidence of the wing was varied,so that it carried a different proportion ofthe.aircraft weight in each of a series oftests. These experiments indicated some ofthe problems faced today by designers ofhigh-speed helicopters, who want to unloadthe rotor by using a fixed or variable wingsurface to generate additional lift.This was the first major project accom-plished by the rotary-wing research group,a small unit which has been maintainedthroughout the years to specialize in theproblems of rotary-wing systems.Flight research was maturing rapidly. Dur-ing 1931, a landmark report was published.NACA Technical Report 369, titled,"Maneuverability Investigation of theF6C-3 Airplane with Special Flight Instru-ments", was the first published reportwhich dealt with the handling qualities ofaircraft, a task that has occupied manyof the Langley and other NACA/NASApersonnel to this day.In 1932, the flight research laboratory wasofficially opened. It was a separate area,with hangar space for aircraft, its ownrepair shop, and office space for the staff.

During 1933, the forerunners of two greatfamilies of airliners first flew: The Boeing247 and the Douglas DC-1. Both wereradical departures from their predecessors;both were all-metal, low-winged craft,with cowled, air-cooled engines and re-tractable landing gear. They had two

Boeing XBFB-1 of 1934,last of the fixed landing-

gear military aircraft.

20

4

I Ohl

25

Boeing P-26 of 1935during flap development

work.

engines instead of the more-commorf tri-motored arrangement. With both enginesoperating, performance was outstanding.But if one engine failed, the available powerwas halved, instead of being reduced onlyby a third.The engine-out situation became a primaryconcern of industry, and Langley was askedin mid-1935six months before the DouglasDC-3 first flewto evaluate the handlingand control characteristics of a twin-en-gined airplane with one engine inoperable.The program had been suggestcd by theDouglas Aircraft Co.Other research paralleled the aerodynamicsand flight work. A new engine lab hadbeen opened in 1934, and began to play animportant part in powerplant development.Part of the workload was directed towardsolution of existing problems, generallyassociated with the cooling of air-cooledengines.But some of the research was aimed at find-ing out the fundamentals of the internalcombustion engine, a type of powerplantthat had been operating for years withoutany real understanding of what went oninside its cylinders.NACA wanted to find out, and initiated aseries of research programs on the funda-mentals of fuel ignition and burning. Goosedown was used to show the air flow patternsof air and mixed gases inside a cylinder,and the motions were stopped by high-speed cameras developed at Langley.Research on aircraft structures was theprovince of a handful of engineers at Lang-ley. Yet out of the very early years grew aprogram that is still active today, and abasic research instrument that is installedon fleets of military and civilian aircraftflying at this moment. It started as a V-Grecorder, to measure the vertical accelera-tions experienced by an airplane flying inrough air. The aim was a simple one: Togather statistical data about air turbulence,

its frequency and intensity, and from thatdata, to evolve criteria for design of aircraft.Today, a sophisticated form of recorder isinstalled in aircraft of all types and sizesand performance capabilities, from single-engined private planes to the eight-enginedjet bombers of Strategic Air Command.The wealth of data is analyzed by com-puter techniques, and continues to expandthe range of man's understanding of thephenomena of flight.By the end of the second decade, the designof aircraft had changed for all time. Theall-metal, low-winged transport ruled theairlanes, and its sister ships made up thebulk of the military air fleets.One of the newest military craft was theBoeing Model 299, prototype of the B-17"Flying Fortress" series, which had flownin mid-1935. In its early flights it surpassedpredictions and expectations, and Boeingwent on record with a letter to NACAwhich said, in part:"You may recall sending us, some timeago, the data which you had obtained onthe so-called 'balanced flap'. It appearedto give such promising results that wedecided to use it on our model 299 bomber."We were also much gratified to find thatthe NAGA symmetrical airfoil lived up toour expectations. It appears that in addi-tion to the effectiveness of the flap, theailerons are more effective, for a given area,than with the conventional airfoil."So, with the use of the NACA cowl inaddition, it appears your organization canclaim a considerable share in the success ofthis particular design. And we hope thatyou will continue to send us your 'hotdope' from time to time. We lean ratherheavily on the Committee for help inimproving our work."But in spite of the enthusiasm of such en-dorsements of the work and contributionsof NACA, a nagging feeling had persistedthat more could be done. The possibility

existed that other countries were makingmore positive contributions to their aero-nautical industries than NACA was makingto the industry of the United States.The scientific challenge to the aeronauticalresearch supremacy of the United Stateshad been recognized and was voicedstrongly in the 1937 Annual Report of theCommittee to the Congress and the Presi-dent of the United States. The report ex-plained that, up until 1932, the laboratoriesat Langley were unique in the world, andwere one of the chief reasons that thiscountry was the technical leader in aviation.But since then, much of that equipmenthad been duplicated abroad and, in somecases, had been bettered so that Langley'sequipment was no longer the best.The report went on: "This condition hasimpressed the Committee with the advisa-bility of providing additional facilitiespromptly as needed for the study of prob-lems that are necessary to be solved, inorder that American aircraft development,both military and commercial, will not fallbehind."For some time, the warning went unheeded;Langley and NACA continued to workunder pressure, making do with facilitiesand equipment that were beginning to showtheir age. There was no particular reasonto improve the laboratories, no overwhelm-ing problem that couldn't be handled inthe ordinary routine of NACA's workingday. In a way, the attitude reflected thegeneral American view toward all worldproblems, not just the specific problem ofmaintaining aeronautical leadership,The war in Europe was far away; thiscountry was beginning to pull out of thecrushing depression of the early part of thedecade. Things looked reasonably good,and who really cared if foreign scientistswere testing rocket motors or developingdive bombers? Whaf difference did asupersonic wind tunnel in Italy make?

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26

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It 1938-1947World War II dominated the third decade ofLangley's work. It broke out in September 1939,and before it was concluded officially in Septem-ber, 1945, the shape of aircraft had beenchanged again.

A handful of technical developments caused thissxond revolution in aircraft design. Sweepback,an aerodynamic innovation discovered almostsimultaneously by several investigators, was ex-ploited in advanced fighter and bomber projectsby German engineers.

Jet propulsion, another example of parallel dis-covery and development, made great strides dur-ing the war. The first aircraft powered by aturbojet was flown in German, on August 27,1939; both Germany and Britain had operationaljet-propelled fighters before the war ended.

Rocket development was paced by the demands ofwar. The first German V-2 (A4) ballistic mis-sile was fired unsuccessfully twice in 1942 beforeits first successful launching in October that year.It was to become operational as a field weaponless than two years later, only a few monthsafter the pulse:jet powered V-1 flying bomb wasused to bomb London.

Guided missile warfare started in August 1943with the German use of radio-controlled rocket-powered glide bombs against ships.

Tuclear weapons were conceived, developed, testedand used operationally during World War II,culminating in the bombs dropped on Hiroshimaand Nagasaki.

Missiles as defense weapons received their firstimpetus when Project Nike was originated inFebruary 1945, to strike at high-altitude, high-speed bombers that would be coming into service.

The destruction of war gave way to the pursuitof more peaceful aims in aviation after the sur-renders in 1945. Landplane speed records wereshattered, first by the British who moved themark over the 600-mph. point with GlosterMeteors basically the same as those used opera-tionally by the Royal Air Force near the end of!he war.

Passenger service across the Atlantic had begunin 1939 by Pan American. A little more thanseven years later, the British De Havilland Air-craft Co. received an order to build two proto-types of a four:jet passenger-carryingaireraftwhich would become the Comet, the wortd's firstjet transport to enter scheduled service.

The first of the research aircraft, Bell's rocket-propelled X-1, had been conceived and designedduring the war. It made its first p9wered flightin December, 1946, and in October, 1947, AirForce Capt. Charles E. Yeager flew it throughthe speed of sound for the first time and pioneeredthe way into the age of supersonic flight.

The month before, a serious research repyrt issuedby the Rand Corporation stated that man-madesatellites of the earth were completely feasible.Others had said essentially the same thing before,but they had been regarded as visionaries at best,and as crackpots at worst. The Rand Corpora-tion was operating under funds allocated by theU. S. government, and had made the .'udyspecifically for the new Department of Defense.

The pronouncement had to be taken seriously, andit was, after the initial speculation by enthusiastswho, saw supermarkets in the sky, giant lenses toburn the enemy, launching sites for atomic bombs,and a host of horrible possibilities in what wasessentially a simple statement that certain tech-nology now appeared to be available.

The earth satellite was not to be for this decade,but the Rand report was a benchmark in man'smeasured tread to the stars. Now there was hopethat the technology of war could be turned to thepeaceful development of space.

28

23

24

Grumman XF4F-3prototype was tested in

the Langley full-scaletunnel late in 1939;production models,

modified by Langleytests, were F4F-4 "Wild-

cats", fighter mainstayof the U. S. Navy early

in World War 2.

ae"

An experimental Navy fighter airplane, theBrewster XF2A-1, was delivered to Langleyin April, 1938, for tests in the full-scalewind tunnel. Systematically, Langley engi-neers measured the drag of the airplaneand of individual parts: Exhaust stacks,landing gear, machine-gun installation andthe external gun sight. When they reportedthe results of the tests, they concluded thatthe top speed of the airplane could be in-creased by 31 mph., more than a tenpercent improvement in performancc.This landmark test was the first in a longseries of clean-up programs performed forthe Army Air Corps and the Navy Bureauof Aeronautics. The success of the test pro-gram established the technique as standardfor both the Army and Navy, and produceduseful design data:applied to future airplaneprojects.

By October 1940; 11 different airplanes hadbeen tested in the full-scale tunnel, in aclean-up progrthn of unprecedented pro-portion. A summary of the tests waspublished that month as an NACA Ad-vanced Confidential Report, to be circulatedonly to industry and the military. The con-clusion stated that "... the drag of manyof the airplanes was decreased 30 to 40percent by removal or refairing of ineffi-ciently designed components. In onc casethe drag was halved by this process. Em-phasis on correct detail design appears atpresent to provide greater immediate possi-

bilities for increased high speeds thanimproved design of the basic ei.mients."The implication of the report was clear.Insufficient attention to detail design wascausing major performance losses. It did nogood to build a clean wing, with low dragcharacteristics, if the wing was dirtied by amachine-gun installation that protruded ata critical juncture. The machine-gun in-stallation was necessary; but so was maxi-mum performance of the airplane. As aby-product of these tests, designers beganto realize that airplane design had to be acompromise between the theoretical idealsof the aerodynamicist's dream and thepractical values of operational requirements.As the clean-up program grew, so did otherprograms at Langley. The pressure was on,higher than ever, and in 1938 the AnnualReport again cited thc need for additionalfacilities. Structural research, the Committeewarned in a letter to the Congress, pro-duced the greatest single need for newadditional equipment because of increasesin size and speed of aircraft. Further, saidthe Committee, the interests of safety andof progress in aeronautics demanded thatthe structures facilities be added at theearliest possible datc.In October, 1938, a Special Committee ofNACA was appointed to study thc needfor facilities and to make recommendations.The Committee's December report urgedthe immediate estabhshment of another

E

research laboratory at Sunnyvale, Califor-nia, plus the augmentation of the Langleyfacilities by a structures research laboratoryand a stability wind tunnel.Congress finally authorized the Sunnyvalestation in August, 1939, just days beforewar broke out. With Europe starting toburn, ground was broken for the newlaboratory at Moffett Field, Sunnyvale.A second Special Committee, headed byCharles A. Lindbergh, was appointed fol-lowing the outbreak of war, and within afew weeks turned in a report stronglyrecommending a third research center forpowerplant work. The report said thatthere was a serious lack of engine researchfacilities in the United States. "At thepresent time, American facilities for re-search on aircraft powerplants are inade-quate and cannot be compared with thefacilities for research in other fields ofaviation."By mid-1940, Congress had authorized anew powerplant research facility. Earlierin 1939, money had been requested for anextension of the facilities at Langley aspart of a supplemental budgetary requestwhich included funds for the Sunnyvalelab. In November, Langley was authorizedto take over additional acreage at LangleyField as the site for a new 16-foot high-speed wind tunnel, the stability tunnel, thestructures laboratory, and supportingfacilities.

The structures laboratory was completed inOctober, 1940, and the stability wind tun-nel in January, 1942, along with a secondtowing tank for seaplane development, andan impact basin where hull loads could bemeasured during simulated water landings.

During 1941, both the low-turbulence pres-sure tunnel and the 16-foot high-speedtunnel became operational in wartime ex-pansion. Langley capabilities had to increaseat the:: same time that it was losing staffmenibers to help organize and operate thenew station at Sunnyvale, now named theAmes Research Center after Joseph S.Ames, NACA Chairman for 20 years.

With this exodus hardly out of the way, asecond began. Congress had authorized theconstruction of the engine research labora-tory in mid-1940, at a site near the Cleve-land, Ohio, municipal airport. The newlaboratory was to be geared solely to theproblems of power generation and propul-sion, from the fundamental physics of com-bustion to the flight-testing, in instrumentedaircraft, of complete powerplant installations.Personnel for the new center at Clevelandalso were drawn from Langley laboratory

staffs. Some idea of the magnitude of thestaffing problem can be gained by com-paring employment figures at Langleybefore and at the end of the war. In 1939,before the expansion moves, Langley had524 people on its rolls, of which 204 wereprofessional people. At the end of the war,more than 3,200 were employed at Langley.During this third decade, the primary jobat Langley was to refine the basic airplanethat its earlier researches had made pos-sible. The propeller-driven, all-metal air-plane with a low wing, cowled engines,retractable landing gear, and flaps neededrefinement. Engine power was on the rise,and corresponding improvements in air-plane performance were possible. But theairplane had to be designed carefully,especially in detail, if maximum advantagewas to be gained.

The drag tests on the Brewster XF2A-1pointed the way. At first in routine pro-grams, and later under the pressures ofwartime demands, airplane after airplanewent through the Langley tunnels, throughthe flight research department laboratory,into the spin tunnel, in model and full-sizeform, until all that could be known aboutthe airplane was measured and reported.

At one time in July 1944, 78 differentmodels of airplanes were being investigatedby NAGA, most of them at Langley.Spin tests were made in the Langley free-spinning tunnel on 120 different airplanemodels. The atmospheric wind tunnel crewstested 36 Army and Navy aircraft in de-tailed studies of stability, control, andperformance.

From these tests came a wealth of data,first for the correction of existing problems,and second for the designers' handbooks.These tests were backed by theoretic-11investigations and experimental programsthat developed airplane components to thehighest degree attainable at the time. Asone example, in June 1938, Langley's low-turbulence tunnel began tests of an airfoilwhose contours differed from earlier de-signs. The point of maximum thicknesswas farther aft, and the trailing portion ofthe airfoil showed an odd reflexed form.The measured drag was about half of thelowest ever recorded for an airfoil of thesame percentage thickness, and the investi-gation became the starting point of Langley'sdevelopment of a series of low-drag airfoils.Less than two years later, the British wereto give North American Aviation 120 daysto come up with a fighter prototype thatmet their requirements. The fighter becamethe famed P-51 "Mustang", after consider-

25

26 able development. It was one of the firstfighters to use an NACA low-drag airfoil,developed at Langley as part of the overallfamily of laminar-flow ai' foils.Flight research work on a variety of air-planes began to build a backlog of corre-lated experiences on the flying and handlingqualities of airplanes. Early pioneeringwork at Langley had given pilots a newappreciation of flying qualities, and thewartime tests sharpened that appreciation.As performances increased, so did some ofthe flight problems. Again using the sys-tematic approach, Langley pilots and engi-neers developed measurable handling andflying qualities for aircraft, and furtherdefined them in terms of wind-tunnelmeasurements.After 19 airplanes had been systematicallytested in flight, Langley engineers prepareda summary report on the group. The reportincluded suggestions for minimum criteriato define a "good" aircraft from the view-point of its handling characteristics.That report became the foundation of theextensive work to be done later by NACA,the military services and industry. Also, itwas a spur to the writing of a militaryspecification on handling qualities, thc firstsuch to be written in this country.Other work at Langley during the wartimeperiod included an extensive study of wingplanform shapes and their effects on thestalling characteristics of an airplane.Variations in taper and thickness ratio,sweepback and twist, were investigated inwind tunnels.Aircraft loads in maneuvering flight, stillsomewhat of a mystery, were studied inflight, in the wind tunnels, and by theory.Changes in stability and control due toengine power, another misunderstood flightphenomenon, were delineated in flight testand in the Langley tunnels.The NACA cowling was refined furtherfor a higher speed range. A special flush-riveting technique was developed to reducethe parasite drag of airplanes.One pursuit plane was plagued by a seriesof in-flight tail failures. Langley engineersisolated the problem, helped suggest asolution. The plane went on to be one ofthe fondly remembered fighters of WorldWar 2.Another Army pursuit developed a "tuck",a tendency to steepen its dive until it"tucked" past the vertical into a partiallyinverted attitude, and trouble began. Windtunnel tests at Langley in the eight-foothigh-speed tunnel, and by the manufac-turer, unearthed the problem. Langleysuggested the dive-recovery flap, based

partly on that experience and partly onsome earlier test work authorized todevelop a dive brake for airplanes.Over-the-water combat flights, and thenumbers of crews lost in ditching on thewater, quickened interest in a way ofgetting an airplane safely onto the water'ssurface. Langley's hydrodynamics testfacilities were turned to a high-priorityprogram of testing scale models in simu-lated water landings and recording theirbehavior in motion pictures.Some of the aircraft couldn't have beenmore poorly designed for landings on water.Belly intakes, bomb-bay doors, or wheelwells scooped up water and served tosomersault the airplane. They sank,inverted.The answer was to develop some kind ofa ditching flap that would counter theeffect of the scoops and bays and wells.Langley work produced such a flap, but itwas never used on any aircraft. The pro-duction changes were regarded as tooextensive.An experimental model of an Army pursuitplane had weak ailerons, a design defectthat could prove dangerous in combatmaneuvering. Langley pilots flew the plane,measured its performance; on the ground,engineers pondered the problems and sug-gested a dual approach. First, they doubledthe deflection angles of the aileron, whichincreased its effectiveness. Then theybalanced the ailerons aerodynamically, sothat the response was light and quick.

The result was an airplane with doubledroll performance, and one that set newstandards by which later fighters werejudged.These were typical problems faced at Langleyduring the war years. It was the urgencyof war that predetermined the direction ofso many of the NACA programs. Most ofthem were aimed at the "quick fix" thatwould get an airplane out of its currenttroubles.But most of the air war was fought withairplanes that had been designed before orearly in the war, and many of these haddrawn on basic NACA data for their de-signs. Secretary of the Navy Frank Knoxsaid in 1943: "The Navy's famous fightersthe Corsair, Wildcat and Hellcatarepossible only because they are based onfundamentals developed by the NACA. Allof them use NACA wing sections, NACAcooling methods, NACA high-lift devices.The great sea victories that have brokenJapan's expanding grip in the Pacificwould not have been possible without thecontributions of the NACA."

As the war progressed, speeds kept edgingup. The pursuit airplanes that experiencedcompressibility troubles emphasized theneed for understanding this new charac-teristic of high-speed flight. It was onething to fix a problem of high-speed flighttemporarily; it could be done empirically,through tests in the Langley tunnels, orby carefully controlled and instrumentedtest flights.But to avoid this problem from the startmeant that the designers had to have abacklog of information, the very kind ofdata that NACA and the industry hadbeen too pre-occupied to collect during thewar years.In spite of the wartime work load, Langleystaff members had been thinking aboutsome of the problems of high-speed flight.In 1939, for example, the Airflow Researchstaff had another look at the basic con-cepts of jet propulsion, a long-known prin-ciple that had briefly come to light in a1923 Technical Report published by NACA.In this respect, NACA scientists were notalone. In other countries, their counter-parts were looking at and working on theproblems of jet propulsion. The Germanswere close to flying an experimental jet-propelled airplane. The British had writtena specification for their first. The Italianswere flying a rudimentary jet-propulsionscheme in a test-bed aircraft.

But jet propulsion, in 1939, seemed like theanswer only to the interception problem.That was not the major concern of theU. S. military services, who were strugglingto get every bit of rang'2 out of their air-craft for strategic reasons. Back hto thefiles went the jet propulsion reports.Another example of high-speed researchwas started in 1941, when a group beganto test in the eight-foot high-speed tunnel,working on propeller designs that could beused to drive an airplane at the then-unheard-of speed of 500 mph. Langley per-sonnel in this group were the nucleus oflater work on high-speed flow that was towin the agency two more Collier Trophies.Working in the high-speed wind tunnel wasa guaranteed wa>, to unearth the problemsof attaining high speeds. But it was onlyone of the methods that NACA tradition-ally had used to obtain design data. Flighttests had to supplement the wind tunnel,and a variety of other kinds of tests inspecial facilities, such as the free-flighttunnel, had to be integrated into a testprogram before the engineers believed thedata was good enough to provide a designbase.At 500 mph., designers would be workingnear the fringe of the transonic region andthe speed of sound. That speed had beendefined as a problem some years betGre,when a British scientist had said that sonic

Early Curths P-40fighter in drag clean-uptests at Langley during1940.

27

28

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1. North AmericanP-51B, one of the most

effective air weapons ofWorld War 2, went

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2. Bell YP-59A undertest in the Langley full-scale tunnel. Plane was

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speed "... looms like a barrier . .." againstthe further development of flight. Thewords, "sonic barrier", passed quickly intothe literature and folklore of flight.Was it a barrier, or only a smokescreen?There was no available way to find out.Some flow experiments had been made atLangley by dropping instrumented andhighly streamlined shapes from high alti-tudes, measuring forces and speeds andcorrelating the two to determine the changein drag and lift at the transonic region.But these results were not too conclusive.There was one acknowledged way to getaccurate transonic design data, and thatwas from flight tests of a full-scale airplane,built specifically to fly into and through thetransonic region.In 1943, such an airplane was conceivedat Langley. More or less simultaneously,others in industry and the military labshad been thinking along the same lines.The Langley study expanded and, in March1944, was presented at a seminar attendedby personnel from the Army Air Force,the Navy and NACA. NACA put its weightbehind the study, and proposed that ajet-propelled airplane be built specificallyfor the purpose of flight research in thetransonic region.This was a pioneering step in aviationhistory. It marked the beginning of a sys-tematic exploration of the transonic regionin flight tests that would win world-widerespect and reknown. It led also to the laterstable of research aircraft operated byNACA and the military in unique pro-grams that supplied fundamental designdata for years to come.Today, research aircraft like the X-15 arebeing flown near the borders of the un-known, in tests which are producing designdata for the aircraft of tomorrow.

This first research airplane was designatedXS-1, and was to be built by Bell AircraftCorp., where much of the original designthinking had taken form in 1943. The con-tract was let by the Air Materiel Commandearly in 1945, and design and constructionproceeded.At Langley, scientists were still trying othermethods. It was not so much a case ofhedging bets as it was trying to developtest techniques that would supplementthose of full-scale flight, and which mightindicate a way to go that was cheaperthan constructing a complete airplane eachtime.One of the unique approaches to obtaininghigh-speed flow was conceived at Langleyin mid-1944. It was based on the existence

of transonic flow in a small region over theupper surface of the wing of a high-speedsubsonic airplane. A small, half-span modelof a wing shape was built and mounted,perpendicular to the upper surface of thewing and aligned with the airflow, near thepoint of maximum thickness. The airplanewas flown into a high-speed dive, andtransonic flow developed over the wing.Instrumentation in the mount of the modelwing recorded the forces and airflow anglesfor reduction into design data after theflight.Revisions in instrumentation, and specif-ically the development of radio telemeteringtechniques at Langley in 1944, prompted asecond series of bomb-drop tests. With aninstalled telemetering package, forces couldbe measured in flight and transmitted to aground station for recording and futuredata reduction.The problem was basically that the avail-able operational altitudes didn't permitenough velocity buildup before impact ofthe bombs. Consequently, the data pointsnever got very much over the sonic mark,and didn't prove too useful.Of these techniques, the most productiveresults were to come from the wing-flowmethod tests. They determined that a thinwing didn't behave at all like a thick wing,and that its characteristics were far superiorfor high-speed flight.Near the close of World War II, a Langleyscientist conceived the idea of wing sweep-back as one method of obtaining higherflight speeds. In effect, sweepback fools theair into thinking that it is flowing over avery thin wing, and it delays the suddendrag rise associated with the transonicregion. In the supersonic speed range, asweptback wing can be designed so that itlies entirely within the shock wave cone.This avoids the problems of mixed flowthat would otherwise occur.Wing sweepback was not a Langley inven-tion, because other scientists were workingon the idea at about the same time. Thefirst intelligence reports that filtered backto industry and the NACA laboratories in.the closing months of the war showed thatthe Germans had taken aggressive advan-tage of the concepts of sweepback, in designsof jet-propelled aircraft thaton paperwere superior to anything under develop-ment either in this country or in GreatBritain.Those designs set the pattern for the post-war years of aviation development. Thedemand was for more speed, higher altitudesof operation, more thrust from turbojet androcket engines. But the XS-1 had yet to

34

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fly. Operational German aircraft withadvanced features were so few, and thereally advanced types so experimental,that there was no way of obtaining muchsolid data from flight tests of full-scaleairplanes.Langley had done some experimentationwith rocket-propelled models, launchingthem from the ground in attempts to getmeaningful free-flight data. This lookedlike a valid test technique, and the workexpanded to a point where a separate testfacility was established at Wallops Island,Virginia, up the Atlantic coast from Lang-ley. The Pilotless Aircraft Research Division(PARD) moved into the area late in June,1945, and on October 18 launched its firstsuccessful drag research vehicle.This was a rocket-propelled model aircraft,designed to evaluate wing and fuselageshapes to provide basic design informationat transonic and supersonic speeds.The test vehicle; became more elaborate.The following June, PARD launched acontrol-surface research vehicle whichevaluated controllability in roll by deflect-ing the ailerons in a programmed maneuver.Wallops Station has long outgrown thatoriginal test site and now is sprawled overportions of the former Naval air station atChincoteague. In recent years, Wallopswork has provided major contributions tothe Mercury, Gemini and Apollo mannedspace flight programs, in tests of escapesystems and other rocket-launched vehicles.

The first flight of the XS-1 was approach-ing, and the test work flights were scheduIedto take place at the Army Air Force flighttest area on Muroc Dry Lake, Calif. Pro-gram personnel were moving to the areafor support of the tests, and Langley trans-ferred 13 engineers, instrument specialistsand technical observers to Muroc. The unitwas designated the NACA Muroc Flight

2

1. Boeing B-29 long-rangebomber model was tmtedfor ditching character-istics in the Langley tankNo. 2 early in 1946.

2. Navy swept-wingmodification of Bell P-63was tested by Langleylate in 1947 to deter-mine low-speed stabilityand stalling character-istics.

36

32 Test Unit; it was the origin of today'sNASA Flight Research Center at EdwardsAFB, which grew out of the site of theMuroc operations.The Bell XS-I was a conservative design.'Its rugged structure was planned to take amaximum load of 18 times its normal flightloads, where most fighters were designedfor only nine times the normal load. Itspowerplant was a proven unit. The designprinciples were simply stated: Avoid allidentifiable uncertainties.One of the uncertainties was the way tofeed the fuel to the rocket engines. Thelightest weight unit would have been aturbine-driven fuel pump, but it wasn'tready when the XS-1 needed it. The deci-sion was made to go with a pressurized fuelsystem, in which bottled nitrogen gas,stored in 12 spherical containers at 2,000psi., was used to force the fuel and oxidizerfrom their tanks to the engine.The pressurized system was heavier, anddisplaced precious fuel so that only enoughwas left for two and one-half minutes ofpowered flight. To make the most of theavailable fuel supply, Bell suggested thatthe XS-I be carried aloft under a speciallymodified Boeing B-29 bomber, and air-dropped for launch.This would accomplish a couple of things,they said. First, it would enable the air-plane to be flown without power in a seriesof glide flights which would establishwhether or not the basic airplane designwas right, aerodynamically, at lower speeds.Second, it would conserve fuel so that itcould be almost all earmarked for the dashthrough the transonic region, for which theairplane was built in the first place.Glide flights were made early in 1946, overPinecastle, Florida, and the first poweredflight following air-launch was made earlyin December that year.Back at Langley, work still was continuingon methods to reach the same speed rangein wind tunnels, or in free-flight with models.One of the major accomplishments during1946 was the development of a rocket-powered research vehicle thLt flew fasterthan 1,100 mph. It was part of the workdone at Wallops Island, and it was launchedto test a series of wing planfonns of dif-ferent sweepback angles and proportions.The wing-flow method of transonic speedstudies was adapted for wind-tunnd use byinstalling a hump in the test section of theseven- by ten-foot wind tunnel at Langley.Mach numbers of about 1.2 times the speedof sound could be reached before the tunnel"choked" with the shock waves of super-sonic flight and the results became uncertain.

It was, and is, the presence of shock wavesin the tunnel test section that makes it sodifficult to obtain meaningful results aroundthe speed of sound. But Langley researcherspostulated that the shock waves could becancelled or absorbed instead of being re-flected. If absorbed, then the test sectionwould be free of the reflected shocks thatdisturb the flow and the measurements.Two Langley researchers, one working withflow theory and the other with experimentsin a small I5-inch tunnel attached to theI6-ft. high-speed tunnel, were able to estab-lish transonic flow in a test section whichhad been slotted with longitudinal open-ings. The slotted throat absorbed the shockwaves and kept the test section clear formeasurements.This was a breakthrough in wind-tunneltechnique. It led directly to the developmentof the slotted-throat tunnel for transonicflow studies, and later, in 1951 after thestory could be told, won a Collier Trophyfor John Stack and his associates at Langley.In April 1947, PARD (Pilotless AircraftResearch Division) launched its first scaled-down airplane in a test for performanceevaluation. It was a model of the RepublicXF-91, a radical fighter design which com-bined turbojet and rocket engines forperformance at extreme altitudes.The success of this test program was fol-lowed by model flight tests of most of theAir Force and Navy supersonic and subsonicaircraft designs.

Then, on October 14, 1947, the sonic bar-rier no longer was a mystery. The BellXS-1, piloted by Air Force Capt. CharlesE. Yeager, reached Mach 1.06 on its ninthpowered flight, in a clear demonstration ofcontrollable flight through the transonicregion.

It was the first of many supersonic flightsto come for the XS-1 (later to be designatedthe X-1 and to be joined by sister ships inthe same series with improved performance)and, later, for other experimental andproduction aircraft.

But it was the pioneering achievement ofthe XS-1 program and the people associatedwith it that was recognized by the awardof the Collier Trophy for 1947 to Langley'sJohn Stack, Lawrence D. Bell of Bell Air-craft, and Capt. Charles E. Yeager of theUnited States Air Force.

Supersonic flight now is no longer unique.Within a few years, airline passengers willbe traveling at speeds nearly three timesthat reached during the first piercing of thesonic range.

But in 1947, the attainment of supersonicspeed was a history-making culmination ofa long research effort that had begun earlyin the war at Langley Memorial Aeronauti-cal Laboratory (now, Langley ResearchCenter). It was also the first step into thefuture of a new and pioneering age inaviationthe age of supersonic flight.

-991416"71,'Sixteen aircraft arewaiting for flight testsat Langley during atypical day in WorldWar II.

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1948-1957The fourth decade of research at Langley wascharacterized by rapid and drastic changes inaircraft types and performance, often shaped bythe application of new technologies drawn fromNACA experience.

In the ten years between 1948 and 1957, thespeed of service fighters in the U. S. Air Forceand Navy, virtually doubled. In September 1948,the world speed record was raised to 670.981mph. by a standard North American F-86Afighter. At the end of the decade, a McDonnellF-101A "Voodoo" blasted its way to 1,207.6mph, beating by a handsome margin the previousrecord set by a British research aircraft, theFair*, Delta 2.Transportation speeds increased also. In 1948,the Br&sh flew the world's first turboprop air-liner, the Vickers Viscount, and followed it withthe _first fiight, in the following year, of theDe Havilland Comet, a turbojet-propelled transport.

The Comet entered scheduled airline service withBritish Overseas Airways Corp. in May, 1952.Two years later; the bright dreams were dulledby tragedy and the Comet was wiThdrawn fromservice.

The remarkable series of "X" aircraft, whichhad been born during the previous decade withthe Bell XS-1, grew into a stable of diversetypes to probe and analyze new problem areas.From the barely supersonic performance of theoriginal X-1, the research series blasted first pastMach 2 and then Mach 3 speeds.The first tentative steps toward vertical takeoffand landing (VTOL) aircraft were taken, anddevelopment later was spurred partly by Me out-standing success of the helicopter in the Koreanaction, and a knowledge of its shorkomings.

The "Century Series" of fighWs, so-called be-cause of their numerical designations whichstarkd with F-100, were developed and flownduring this decade, and ut new performancestandar4%. They also posed new stabili0 andcontrol problems, such as roll coupling and pitch-up, which were to plagtu their deniners andNACA for solutions.And finally, in the closing months of the decade,North American Ariation was awarded Me con-tract for the XB-70 bomber, an awesome aircraftinkndtd to fly at three ames the speed of sound.The airplane hat' cane fast and far in the decade

between 1948 and 1957. The Berlin Airlift,which began in June 1948, was flown with thepiston-engined transports left over from WorldWar 2, and designed before then.

The Consolidated Vultee B-36 was the standardbomber of the Air Force, and jet-propelled fighterswere just getting to squadrons. There was achange in the offing, marked by the first flight ofBoein* sos XB-47, a sikjet sweptwing bomber,

dtwhi took to the air for the first time February 8,194:4

But the U. S. went to war in Korea with left-over Boeing B-29 bombers, and the first kill wasmade by a North American F-82 Twin Mustang,a piston-engined fighter.

In November 1950, the first dogfight between jetaircraft reared the sky over Korea and set thepattern for future combat.

In June 1951, the Bell X-5 flew for the first time.One of the research aircraft, it was characterizedby its ability to change the sweep angle of itswing in flight. It was the precursor of the GeneralDynamics F-111A fighter and the Boeing supersonictransport.

Air transportation made a tremendous impact onthe public during the Berlin Airlift. Three yearsla' !, air passenger miles overtook Pullman pas-senger miles traveled for the first time. The trendhas nmer reversed.

The Boeing 707 prototype, first of a long line ofjet transports, made its first fiight July 15, 1954.!ate, the French made a unique contributionwith the Sud Aviation Caravelle, whose rear-mounted turbojets set a style trend. The Caravelle&st fiew May 27, 1955.In October that year, Pan Amerkan World Air-ways ordered 45 jet transports, 25 DC-8s fromDouglas and 20 Boeing 707s. The first round ofjet orders was sparked by this move, and the jetrace Was on.

In January 1951, the Atlas intercontinentalballistic missile program was started. It was todraw heavily on aviation's scienhfic, engineeringand organizational talents. But more than that;it was to become the tail that wagged the dog.

Frc Pn a small start, the Adas and its descendantsgrew to dominate the aircraft industry, its edu-cational *Item, its management techniques, itspermtmel moves and its funds. Is men changedMt name of Ms industry to "aerospace!!! 40

Before the decade ended, the unexpected happened.On October 4, 1957, a rebroadcast "beep-beep-beep" signalled that the first man-made satelliteof the earth was in orbit, and that it was Russian.Sputnik's signal had a mocking sound to frustratedU. S. engineers.

The insult was repeated less than one month laterby Sputnik II and a passengerthe dog, Laika.Sputniks I and II triggered a chain reaction thatis still mushrooming today. They affected Langleyin a way that re-oriented its thinking, re-allocatedits money, and redirected its efforts. And it forcedthe birth of the National Aeronautics and SpaceAdministration in 1958.

It was to be a long step from the first breach-ing of the sonic barrier to the achievementof sustained, efficient supersonic flight, 'Indnowhere was that better understood thanat Langley.The Bell XS-1 had flown supersonically bythe "brute strength" method. It had littleendurance. It had to be carried aloft bya mother ship to conserve the fuel whichwould have normally been used for takeoffand climb. It was powered by a rocketengine with a prodigious appetite for fuel.It was a great research airplane, but itwould have made a terrible operationalmilitary or civilian aircraft.More practical designs had to be achievedand NACA mounted an attack on theproblems of sustained supersonic flightalong a number of salients.The jet engine had grown up and promisedenough thrust, at operational altitudes, topropel a less-radical airplane than the XS-1through the speed of sound. The generalconcept of the swept wing indicated thatdrag reductions were achievable, enough tocomplement the available thrust and makefor supersonic flight.Some data was available on components oron generalized shapes that indicated trendsbut didn't solve any of the detailed designpcoblems. The question of how to get highlift out of a thin wing had not been answered.Efficient air inlets for supersonic speeds werelacking. Control systems were still tied tosubsonic data obtained earlier.And worse, there was a realization that nolonger was the airplane a simple linear design,a finished structure made up of componentbuilding blocks that had each been designedseparately. The design of a supersonic air-plane, and in fact, of any efficient high-speed airplane, was going to have to be anintegrated whole, in which each componentinteracted with every other, and nonecould be changed without affecting theoverall design, perhaps radically.This was the general statement the prob-

lem that faced Langley researchers as theyentered their fourth decade of researchwork. The supersonic age was crowding inon them. Requirements for military air-craft were beginning to work into andbeyond the transonic region, and new datahad to be obtained fast.Fortunately, the slotted-throat wind-tunneltechnique had been developed just a coupleof years before, and was beginning to promiseaccurate results in a region where test workhad been uncertain, at best.Wind tunnel facilities, always a stming por-tion of the Langley laboratory, were plannedaround the slotted-throat concept. A neweight-foot transonic tunnel was first approvedfor construction by the Research and De-velopment Board of the Department ofDefense in May, 1949. In December ofthat year, the original eight-foot high-speedwind tunnel, an existing Langley facilitywhich had been converted to a slotted-throat test section, ran with sustainedtransonic flow for the first time.One year later, the same trick was per-formed in the I6-ft. high-speed tunnelconverted to a slotted throat.This work led directly to another CollierTrophy in 1951, awarded to Langley'sJohn Stack and his associates fo1 their workin the conception, development and practi-cal application of the slotted-throat fortransonic wind tunnels.Continuing work by the Pilotless AircraftResearch Station at Wallops Island paral-leled the studies in the transonic tunneland extended them into the supersonicspeed range reachable with rocket-propelledmodels.Slowly, the transonic region yieldea to prob-ing and analysis. The basic problems beganto be defined, and the numbers that weredeveloped in tests showed where the problemsreally lay.The biggest difficulty in getting an airplaneto fly supersonically was to get it throughthe transonic region rapidly so that itdidn't have to waste precious fuel in a slowacceleration through the Mach one range.The problem was that, in the transonicregion, there was a sharp increase in dragcoupled with a corrfsponding decrease inlift. Changes in lift meant that controlproblems might well appear. They couldbe handled, if they were defined, under-stood and curbed. That knowledge was tocome later.For the moment, the concentration was ongetting through the transonic region. Howcould the drag be reduced?One of Langley's scientists, Richard T.Whitcomb, had an intuitive feeling that the

drag rise was due to the interference be-tween wing and fuselage. Some tests proved,to his satisfaction, that this was so.Adolf Busemann, a transplanted Germanscientist who had contributed to highspeedaerodynamics over at least a decade, spokein November 1951 about the "pipe flow"characteristics of the transonic flow region.What he meant was that cross-section areasof the stream tubesthose nebulous sur-faces defined by a cluster of streamlines inair flowdidn't change as the flow passedthrough the transonic region.Whitcomb thought about this, and betweenthe insight from Busernann's commentsand some additional tests, he derived thearea rule, a basic design concept whichin the words of a Langley associatemadesustained supersonic flight possible.The area rule, crudely stated, says that thecross-section areas of an aircraft should notalter too rapidly from the front of the planeto the back. This minimizes the flow dis-turbance and the transonic drag rise.For example, the presence of a wing on afuselage adds extra cross-section area to theairplane. To compensate for the additionalwing area, some area must be removedfrom the fuselage. The result is an indenta-tion on the fuselage where the wing islocated. This "wasp-waisted" appearance,or "Coke-bottle" shape, is one characteris-tic of the early application of the area ruleto transonic flight.Tests of the concept as a design tool beganin February 1952, and they were quicklyapplied to two military aircraft: Convair'sXF-102, which showed no hope of reachingits low supersonic design speed, and theGrumman XF11F-1, which had, in theearly design stages, a low supersonic speedas one of the design goals.

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Both airplanes later sliced through thetransonic region with little difficulty, andwith no more power than before.The work was kept under wraps at Langley,because it was a genuine breakthrough inairplane design. It was finally releasedpublicly in 1955, when Whitcomb receivedthe Collier Trophy for 1954 for ". . . dis-covery and experimental verification of thearea rule, yielding higher speed and greaterrange with the same power."The work continued, and extensions of thetransonic area rule were developed fordesign of supersonic cruise aircraft. GeneralDynamics' experience with the F-102 designhad made the company a believer, andthey designed their B-58 bomber using thesupersonic application. It was the firstairplane to be designed by the supersonicarea rule concept, and it made its firstflight November 11, 1956.Part of the success of the B-58 bomber wasdue to a tiny delta-winged aircraft with afighter designation: XF-92A. This had beenbuilt as a fighter airplane, and assignedlater to a research program to determinewhether or not the delta-winged planformwas the correct approach to highspeedflight.

It was barely supersonic in a steep dive,according to one of the Air Force pilots whotested the XF-92A. But dive tests showedthat transition through the transonic regioninto the low supersonic was easier with thethin delta wing than with either the thickersweptwing F-86 or the straight-winged F-94,both of which were capable of crossingthe transonic region in a dive.The XF-92A later joined the NACA groupof research airplanes, and was extensivelytested in flight before its retirement.That group of research airplanes, born during

Research aircraftpioneered flight into thesupersonic range and ledthe way to supersonicfighten and b.ombers.Second Bell X-I, flownby NACA pilots froml948, later modified tobecome X-I E.

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the previous decade at Langley, in themilitary services and industry, grew to beone of the most valuable sources of aircraftdesign information ever assembled.The Bell X-I, progenitor of the series, hadflown through the sonic speed range in 1947.A second resea,ch aircraft, the straight-winged Douglas D-558-I Skystreak, hadbegun its flight test program early in 1947,and by August that year had establisheda new world speed record of 650.8 mph.

A second D-538 design, the Skyrocket, wasdeveloped by Douglas Aircraft and theNavy. It featured a swept wing in additionto a rocket powerplant in combination withits turbojet. Three of the sweptwingcraftwere built, and one of themrocket-pro-pelled and air-launchedbecame the firstaircraft to break the Mach 2 mark.A major step forward was the Bell X-2,intended to explore the region of flightabove 100,000 feet and up to speeds ofMach 3. Built of K-monel and stainlesssteel to solve the expected heating problems,the Bell X-2 was powered by a throttleablerocket engine. It was a short-lived program,marked by tragic losses of both airplanesand two pilots. But in its brief moment ofglory, the airplane reached a peak altitudeabove 126,000 feet, and a speed of Mach3.2.

But more than speed and altitude per-formance was in the minds of the engineerswho worked with the research aircraft.The Air Force funded a program on theNorthrop-built X-4, a tailless airplane de-signed on the premise that elimination ofthe horizontal tail surface would reduce the

problems associated with wing-tail com-binations in the transonic region. The air-plane became a reliable test vehicle, althoughits speed range was on the low side of thetransonic region.There was an X-3, originally conceived toexplore the problems of sustained super-sonic flight. Needle-nosed and with tiny,straight-tapered wings, the X-3 proved tobe underpowered and overloaded. In spiteof that, experienced pilots kept the airplaneoperational over a four-year span from1952 to 196, and succeeded in obtainingmuch data on the behavior of very thinwings in the transonic regi,m.Flying the X-3, which was an airplanewhose inertia characteristics were differentfrom almost all of its predecessors, uncovereda highspeed flight problem ot inertialcoupling. Crudely stated, the airplane wal-lowed in the air. If the pilot wanted toturn the airplane in a banked attitude, theunusual distribution of the airplane's mass--strung out along the fuselage, but esseil-

tially zero in a spanwise direction resulted

in a yawing motion as wc11. Sometimes theyaw was wild and uncontiollable; the firstversion of the North American F-100 super-sonic fighter broke up in the air from thisuncontrollable motion.

As a sidelight, the problem of inertial cou-pling had been studied in theory and re-ported by Langley in 1948. The repolt

nguished in files until trouble sct in. Thenit became a keystone of the flight andtunnel-test programs tht.t were mountedon an emergency basis to solve the problem.

The fifth designated X-airplane was a dif-

'

ferent approach. It was built around theconcept of a variable-sweep wing whosesweepback angle could be changed in flight.The concept was probably born, and cer-tainly was advanced, in the Langley labora-tories, although the genesis of the idea isargued today and remains controversial.The fact is that Bell Aircraft submitted aproposal to the Air Force in July 1948 fora research airplane whose wing sweep wasvariable in flight. The USAF went to NACAwith the suggestion that the airplane be-come part of the joint research aircraftprogram. NACA accepted, endorsed theprogram, and the X-5 began to take form.How did it originate? The thought probablyoccurred to several people who thoughtabout one of the main problems of thesweptwing aircraft. The layout was fine forhighspeed flight, but it left much to bedesired at the low-speed end. If it werepossible to vary the wing sweep from zeroat low speeds to the optimum anole forhigh speeds, the problem could be solved.In 1945, work at Langley began in the free-flight tunnel on a skewed wing, pivoted ona vertical centerline and rotating so thatone wingtip moved forward and the otheraft. This curious configuration "... ex-

2

.67 e*t14"4"T

1. Bell X-1A, briefly onNACA roster in 1955.

2. Bell X-Z flown onlyby USAF pilots, wastunnel-tested at Langley.

.3.41.

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45

hibited surprisingly good flight characteris-tics up to skew angles of about 40 degrees."Results were published in Technical Note1208.Two years later, a model of the Bell X-Iwas modified for tests of variable sweep inthe Langley 7- by 10-ft. tunnel. The ex-periments produced results that showedvariable-sweep concepts to be feasible. Thetests also showed that it would probably benecessary to move the wing along a fore-and-aft line in order to keep the stabilitycharacteristics within the desirable range.Bell's background in research aircraft design,and the work done by Langley in the windtunnels from 1945 to 1947, were combinedby Bell in the proposal for the X-5.The airplane first flew June 20, 1951. Itbecame part of an extensive flight-test pro-gram which investigated the effects ofsweep on perfomance and flying qualities.The sweep angle was changed in flightmany times with no problems.The earlier work at Langley was provedright, though, because the Bell X-5 wasdesignedfortunatelywith a mechanismthat moved the entire wing forward as itwas swept back, in order to keep stabilityand control positive.One important benefit, which remains rela-tively unknown today, was the knowledgegained about the response of a high-speed,highly swept airplane to gusts during fast,low-altitude flight.The X-5 was flown near the ground withits wings swept fully back to 59 degrees,and the data obtained during those runswas to become an important considerationin the later design of variable-sweep fightersfor their tactical role.Prior to and during the X-5 test program,Langley tunnels and other facilities wereused in parallel studies on models in windtunnels, at low speeds and at high, usingthe transonic bump technique, and in-flighttests of scmi-span models using the NACAwing-flow technique.NIeantime, the Navy and Grumman Air-craft Engincering Corp. were developingthe XF10E-1, a variable sweep fighter firstflown in May 1952. Langley tested modelsof thc XF10E-1 in the transonic wind tunneland in flight, using the rocket-propelledtechnique at PARD, Wallops Island.The airplane was a failure, even though theincorporation of variable sweep contributednothing to that failure. The.-e were noserious mechanical problems with thc mov-ing wing, but flight and oth n. limitationson thc airplane resulted in little or no usefuldata on the application of variable sweepto a military aircraft.

The variable-sweep studies continued atLangley only on an interim basis for anunther of reasons. First, in the early 1950s,there was no military requirement for sus-tained supersonic speeds; interest was limitedto a subsonic cruise to target areas with asupersonic dash over the target.Second, there was no low-level operationalrequirement to minimize the chance ofradar detection. The ability of a highlyswept aircraft to fly low and fast, provenin some of the test flights of the X-5, wasnot yet to be put to the test of a militaryapplication.But later, a mffitary requirementWS-110was proposed that required a sustainedsupersonic cruise for a strategic bomberdesign. Other military mission requirementsbegan to include a low-level penetrationrun at high speed. The need for short-fieldcapabilities and ferry range in aircraftbecame of military concern.All of these considerationssustained super-sonic cruisc, low-level penetration at highspeed, STOL capability and long ferryrangewere to coalesce later in designsusing some of the conccpts of variablesweev., pioneered at Langley. But for therem.; ider of the decade, work persisted ata low levd of activity.But %VS-110 was beginning to create adesign revolution. In late 1954 thc needwas advanced for a B-52 replacement with

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6.L411.11.:1

the capability to operate from existing run-ways and to use existing maintenance facili-ties. It should have a minimum unrefuelledrange of at least 6,000 nautical miles, anda speed that should be as high as possible.Supersonic flight over long distance, withthe conventional airframe-engine combina-tions of the day, resulted in proposals forgigantk aircraft with incredible and com-plex layouts. The designers were sent backto the drawing board3, and WS-110 wasreduced to feasibility studies.North American's proposal for the WS-110was finally chosen, and after much travail,became the X11-70 program with all itsassociated political and technical problems.It eventually lost out to the concept of amixed missile-and-aircraft force, and to theeventual replacement of that mix entirelyby missiles.Langley scientists claim no major role inthe concept of the B-70. But they emphasizethat the Langley research program in sup-port of the airplane directed thcir attentionto the problems of sustained supersonicflight and emphasized thofic problems tosuch an extent that they have been thinkingabout long-range supersonic cruise aircraftever since.During this fniitful decade at Langley, oneof the most important and significant air-plane designs of all time wa 3 born: TheX-15 hypersonic research aircraft. Its origin

I. In quarter-scale, theBell X-I is investigatedin the I6-foot transonictunnel's slotted throat ina Langley test program.

2. Dynamic models ofthe Bell X-5, a variable-sweep mearch airplane,show the different wingforms tested at Langleyin the spin and free-flighttunnels.

46

41

42

2

47

.1

1

Nr,

is traceable to a dmilment of January H.1952, from Bell Aircraft Co., who had I wenassociated w ith the design and developmentof thr X-I. X-2 and X-.) research aircraft."Flie document included a puposal for amaimed hyper-sonic research aircraft usedin support of a proposed N.ACA grolpwhich would Ire formed to evaluate andanalvie the basic probleiTls 111 11%pr rv.onicand space flight.In June I952. NAC,Vs Committer On Aero-dynamics passed a resolution ivhich recom-mended that NACA increase its programfor the speed r..nge between Mach 4 andMach 10. and that it loxik at even highervelocities.

1. First Langlev VTOL model. this mdimentaryaircraft pinpointed probkm areas for subsequent test

programs.

2. Convair XFY-1, tail-sitting VTOL developmentaircraft, was checked in free-flight model form in the

30- by 60-ft. full-scale wind tunnel at Langley.

A. Flaming halo was produced by ramjet propulsionfor rotor tested on the Langley helicopter test tower.

pler'

&Wabash..

Langley set up a study committee to eval-uate the Bell suggestions and an accompany-ing proposal for a rocket-propelled, variable-sweep manned research aircraft. In addi-tion, two unsolicited proposals for aircraftof similar performance had come throughthe NACA channels. One was for a two-stage vehicle and the other was for a majormodification to the existing X-2 design.In March 1954, NACA's interlaboratoryResearch Airplane Panel decided that acompletely new research vehicle was thebetter route to travel. The problem wasreferred to the four NACA laboratorim fordetailed study of goals and requirements.By July that year, the studies had crystal-

lized to the point that two of themLang-ley's and that of the NACA High SpeedFlight Station at Edwardscould concludethat a Mach 7 research airplane was feasibleand desirable.

Air Force and Navy representatives metwith their counterparts at NACA thatmonth and listened to the presentation ofthe proposed research airplane. Followingthe meeting, industry teams visited Langleyto discuss the pmposals in detail.In October 1954, the Committee on Aero-dynamics held a meeting which producedan endorsement of the NACA proposals.Air Force and Navy joined NACA in ajoint task of defining the specification. Itsrequirements coincided generally with theresults of the Langley study.

In December 1954, NACA made th, formalpresentation to the Air Technica! AdvisoryPanel of the Department of Defense. Theyapproved the idea, specifying that NACAshould he the technical managers of theproRtam, and that the panel itself wo-ildhave the chance to review proposed designswhen submitted hy indirstry.This was followed by a memorandum ofundemanding among Air Force, Navy andNACA, which established the ResearchAirplane Committee to direct the projecttechnically. initial steps toward a designcompetition were taken D-rember 30 andinvitations for proposal, %TM sent to industry.

The proposals carne in the following sum-mer, and by autumn 1955 had been eval-uated. North American Aviation wasawanled a contract for three X-15 air-craft in June 1956; Reaction Motors divisionof Thiokol Chemical Corp. received theengine development and pnxItiction contract.

Wind-tunnel testing and work on develop-ment of structural components began in1956, and was able to produce enough use-ful data to enable construction of theairplane to begin in September 1957.The first flight of the first X-15, in a power-less glide, was to be made in June 1959.NACA, then NASA, did not begin to flythe X-I5 until after its delivery to thegovernment in March 1%0.Pmgrams like the X-15, the XB-70 and thedevelopment of such concepts as the arearule and variable sweep are the spectacularevidence of work done in research labora-tories. But behind these tangible forms laymany man-years of effort in the painstakingdevelopment of systems and components forflight.During the same years of these aircraftdevelopments, NACA was laying the ground-work for the decades of supersonic flight in

48

43

44 military and conynerrial airplanes thatwonld snrelv follow.Confignration 5tildiet, both generalized andspecific. were made wind tnnnels, de-veloped in theory. and es-ablated ln flighttests with rocket-propelled models. Familiesof wing planforms for highspeed flight weredeveloped. as were control systems andhigh-lift devices for the thin rwept snrfaces.Such aerodynamic contrihntions to thescience of highspeed flight as the low-sethorizontal tail, located to avoid pitch-lipproblems, and inboard ailerons. which werrmore effective and less stressing than con-ventional wingtip contmls, grrw ont of theresearrh program' at Langley. They wereapplied to the Cennirv Series of fighters.among other airrraft.In stnictlires. the work of the Langleylaboratory fonnd eager acceptance by theanalysis of fluttrr and vibration problemsAn accelerated effort began early in 197.5when the 19-ft. tunnel was modified toenable tests of dynamic flutter models to bemade. The tunnel thrn conld he pin overa greater range of Mach numbers andReynolds Numbers, at an altitnde rangefrom sea level to an equivalent of 95.000feet.

Tests like the ones conducted in the modi-fied tnnnel. conpled ith theoretical analy-sis, enabled Langley engineen to make sig-

,.411111-

nificanr contrilintions to the developmentof techniques for predicting flutter attransonic and snpersonic speeds.Additional contributions were made in theareas of fatigne criteria and prediction ofloads on structiires in flight and on thcground.Helicopter work, which had begun inpioneering effort diming Lang Irv's seconddecade, and was accelerated with the avail-ability of the rotor test tower in the nrxtdecade, continued in this trn-year period.It involved flight tests of the new machines,to gain an appreciation of their handlingqualities and to hrlp drfinr thrm for thrbenefit of fliture designs. Special hrlicoptrrairfoil se-tions cry- devrloped. rvitrndingthe fundamental work donr on airfoils byLangley in it' early wind-tlinnr1 work.

Iirlicopter stabiliiv. a tough mit to crack,was anal. zed and mrthods were developedto predict it The loads imposrd hs gnIt:and maneuvers were eNplored in flight andin trn work on model- and fn11-"cale rotors.

Fundamental work in hypersonic arm-dynamics pointed the way toward the X-15researrh airrraft program. Bnt it also laid asolid fonndation for the coming programsin manned space flight and the futnre appli-cations of h. personic technology to commer-cial transport.

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A landing-loads track began operation dur-ing this decade. using a car propelled bya high-pressure stream of water. The carcould carry typical aircraft landing gear,and subject them to the dynamic loadsitnations encountered in aircraft landingsand arrested landings.The velocity-gravity-altitude (VG1-1) re-

/ corder's, installed in many lircraft, pmdnceddata that was used in 1950 o a world-wide analysis of atmosphenc turbulenceand gusts to guide aircrart designers inacconnting for these perturbations in other-

- wise-steadv flight rrgimes.The flexible wing, an entirely nrw concepta lifting structure. was conceived just after

".. the war at !Angles . Patented in 1918 as a

1 kite, thc flexible wing has grown into a re-markable variety of applications wherelift-drag ratios need not exceed 3.0This decade saw the sophisticated develop-mem of one of the flight researcher's mott

tools: Thr flving-model techniquie.This grew mit of earlier work in thc free-spinning tunnel, where dynamically similarmodels of aircraft were forced to spin in aa vertical tunnel test xettion, and the behavior#was photographed and observed.The idea of thc free-xpinning tunnel wasextrapolated to a free-flight tiinnel dnringthe mid-1930s. The technique was one wayto obtain dynamic stability and control

-.1FaalLasoLva

40

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7111L11111W-aidli

1111

,

11 1. Structures research at Langleyincluded studies ofmethods to control failuresof pressurized fuselages.

2. Ground loacis nn high-speedaircraft landing gearsare checked on thishydraulic-jet propelled carriageat Langley's Land;ng LoadsTrack facility.

3. High-speed jet-propelledseaplane studies weremade at Langley.

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1

I. "rlir ahmarineAlbacore, then theworld'A (mu-0, wail

trord in model formin the Langley full-wale

tunnel in 1910.

2. Modeb of theConvair F-102 before

(left) and after (right)application of the arrarule were fliizht-teordfrom the Pilot lett Air-craft Rciiearrh Stationat Wallops Island, Va.

abed.'

characteristics on a small-scale remotelycontrolled model. By 1937 a small tunnelhad been developed which was a pilotmodel for later tunnels to come.The model work conducted in this primaryfacility led to the construction of the 12-foot Free-Flight Tunnel, which startedoperating at Langley in 1939. That tunnelwas used until the early 1950s, when animproved technique was developed andapplied in the Langley Full-Scale Tunnel.That technique, using remote-controlled,powered models, is used to determine low-speed dynamic stability and control charac-teristics. It is primarily a qualitative evalua-tion, and the data is in thc form of pilotopinion and motion pictures of the behaviorof the models.Other free-flight techniques were adaptedat Langley during this time period, includ-ing the model airplane enthusiasts' U-con-trol ideas. Langley's Control-Line Facilitystarted operation in 1955 primarily to in-crease research capability in studies oftransition of VTOL aiicraft. Rapid transi-tions from vertical to horizontal flight, andback again, can be made with the control-line tf!chnique. Tests in the Full-ScaleTunnel arc limited to very slow transitionsbecause it takes a long timc to change thespeed of the air stream in the tunnel.The cnd of thc decade saw the beginningof serious work on hypersonic research.The X-15 program was one manifestationof the drive to investigate the upper reachesof the supersonic flight regime and on intothe hypersonic.In 1935 Langley, along with Ames Aero-nautical Laboratory, began to develop aseries of high-temperature facilities formaterials and structures research. High-temperature problems had been singled outas the main barrier to the successful achieve-ment of hypersonic flight, and NACAwanted to break down that barrier.At Wallops Island, Langley was developingand firing multiple-stage rocket vehicles,aimed at higher speeds and altitudes. OnAugust 24, 1956, the division launched suc-cessfully a five-stage, solid-propellant rocketvehicle. It reached a speed of Mach 15,far into the hypersonic region and begin-ning to touch the Mach numbers thatwould be encountered in ballistic missilere-cntry bodies and in the return of menfrom space.At the Langley Structures Research Divi-sion, work began during 1956 on the arc-jet facilities whose abnormally high tem-peratures generated the environment of

p.ii-entry flight. Two dozen of these arc-jetotilities subsequently were developed and

used in research on materials and structures, for re-entry.

During July 1957, Langley engineers beganstudies of the use of solid-fuel rockets to

4- launch and orbit a small payload. Theipurpose was tt, develop an inexpensivelaunching vehicle that could be used for

4 scientific satellite work.t What resulted finally from this work was

the concept and development of the Scout,a solid-propellant launch vehicle that ha:,

Ibeen responsible for lifting many scientificpayloads into space for government, privateindustry and forc:gn government spaceefforts.

Late in 1957, Langley proposed the basicballistic form for re-entry from space thatwas later to become the characteristic shapeof the Mercury capsule. Winged and wing-less glider configurations for manned space-craft also were proposed, and later wouldbecome incorporated in the Dyna-Soar andthe Apollo programs.This decade started with the first probingof the supersonic region by a manned air-craft. It progressed, rapidly, through rou-

1:v1

tine supersonic flights by military pilots instandard service aircraft.The decade drew to an end with the suddenawareness of the importance of space flightand the use of space for exploration anddefense. Sputnik spurred the rapid develop-ment of ideas for vehicles that could getmen into space and return them safely inthe searing heat of re-entry.The aeronautical techniques developed overthe years were soon to be placed in theservice of a new technclogy whose environ-ment was airless, wl-ere winged flight wasimpossible, where aerodynamic controlswere useless, and where turbojet enginescould not maintain their internal burning.But those aeronautical techniques were tobeccme among the most important contri-butions to the success of nianned spaceflight,because what went into space had to passthrough the atmosphere on its way there.And what was to come back from spacehad t3 traverse the atmosphere in the fieryrush of its homeward voyage.Langley's work was predestined for the nextdecade.

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Mao

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1958-1967To comprehend aviation's rate of growth duringthe part decade, look back to 1938. Sputnik hadjust been launched, hut the world's air travel wasbeing dont in piston-engined airplanes crurring atspeeds comparable to those of Work' War 2

fighters.

There were no jet transport; in operational serrift.The giant airliner( of the do carried 70 parsrvi-gers. 3fore people armed the Atlantic ht shipthan hy air.Pier, were no artronator. Man had _yet to sethir own planet from a height greater than a fewmiles. The moon war rtill at far away at thesun, in terms of ri hat was known about it.

The exploration of (pace war bring done at itslouyr fringes with rounding rockets fired verticallyinto the uplyr atmosphere. .4 few pioneeringdivert, with self-contained breathing apparatus.urfe finding the depth( of the Wean In be a new

f- frontier .for exploration.

Rut in 1967. the let tran(port dominates the air-lanes of the world, carrring or Mara as 250passengers at high subsonic speed( and altitudesnear the stratosphere.

Under construction are giant tranrports, Mat cancarry up to ten times the Illanbfl of people whosat in the airliners of a decade ago. The super-sonic transport, now under constructron, willcruise the world' s air routes at speeds more thanthree times those of the first jets, and more thansix times as fast as the piston-engined transportsof a decade ago.

Trans-Atlantic ship travel is almost negligiblecompared to trans-Atlantic air treffic.

Astronartc have orbited the earth, walked inspace, performed manual labor in the void, photo-graphed earth from altitudes of hundreds of miles.Unmanned satellites and probes have landed onthe Moon, photographed its unseen side fromlunar orbit, surveyed possible landing sites on itssurface.

Tht oceans of the world have begun to yield toscientific and systematic exploration, made pos-sible in many instances by the same technologiesthat helped to conquer first the air and then space.Ten years ago, jet pnpulsion and sweptbackwings were for military aircraft only, and forthe first few jet transports that were enteringtraining programs with the airlines Y" the world.

Vertical takeoff and landing aircraft were freaks,

with freakish performance in most cases, and farremoved from the pots:Inlay of deployment witha military service.

.Supersonwflight war the prOrlltie of a fell" mili-tary pilots, and the maoriI of ripersomc flighttime war bring logged well be:ort Ifach 2.0.7 itanium war a strange wird, arid the amountused in aircraft construction could he warlord inpounds rather than larger units.But gyadually, the tengible evidence of progresshegan to show. In 0, tobrr 1.958, jet passengerserrice war started across the .Vorth Atlanticby British Overseas Airways Corp., and thatyear, for the first time, mare passengers crossedthe Atlantic by air than crossed by ship.

In 1950. the Apollo project was efficially an-nounced, and the &ha satellite, an irilatableballoon for CAW, flight, was launched successfully.

Cdr. Alan B. Shepard, Jr., became America'sfrst arronaut with a sub-orbital.flight as part ofProject Ifercury in 1961.Four pilots of the X-15 retrarch ai.yraft won theCollier Trophy for 1961: Maj. Ii'oert White,

SAF; Clr. Forresf Petersen. 1,..."; and twocirilian pilot from the .Vatirmal Aeronautics andSpare Administration, Scott Crosffield andJoseph Walker.

In June 1963, President John F. Kennedyannounced that the United States was going tidevelop a supersonic transport. In France andGreat Britain, a European consortium of aircraftmanufacturers already was hard at work buildinga supersonic transport, still scheduled toffy earlyin 1968.

On Dec. 17, 1963, just 60 years after the TVrightbrothers took to the air in hesitant flight over thesands of Kitty Hawk, Lockheed fiew for the firsttime its newest heavy cargo carrier, the C-141A.

Other labors at Lockheed were unveiled to anawed public when the A-11 was announced earlyin 1964. This Mach 3 airplane possessed muchof tht technology that could contribute to the de-velopment of a supersonic transport, especially inthe knowledge of the problems of sustained fiightat the tri-sonic speed which was the goal of the1_7. S. SST program.

The XB-70 made its firstftight, even though theaircraft was obsolete from the day it rolled outof the factory into the bright California sunshine.Two aircraft, which owed much of their 54

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conceptual designs and development work toLangley, made first flights in 1961: TheGeneral Dramics F-111, a variable-sweep

fighter. a.ai the tri-sertice I.TOL transport, theXC-112.4, built by a consortium of Ling-Temco-!Sought, Ryan and Hiller.

This .50th year of Langley opened with anotherlandmark event in aviation. In January, con-tracts for development and construction of theU. S. supersonic transport were awarded to theBoeing Company, for the airframe, and theGeneral Electric Co., for the powerplants.

To the scientists and engineers at the LanglgResearch Center, this decade has seemed a littlelike the situation that faced Alice, when the RedQueen told her that she had to run as fast as shecould just to slay in the larne plate.Somehow, the work done at the Langley centerseemed to run that extra lnt faster, so that itcould pace these developments in aviation. Andthis war dont in spite of the necessary turmoilcreated ht the complete change in organilahonthat occurred in 1958 with Mt formation ef theNational Aeronautics and Spare Administration

from the .Vational Advisory Committee for Arro-natdics and other organizations.Langley Research Center, once the only labora-tory for NACA, now is one of several. But it hasmade possible, over the years, formation of otherlaboratories which found their origins at Langlg.The Lzwis Research Center, where powerplantwork is the primary objective, had its roots in theengine laboratory opened at Langley in 1920.Tht Ames Research Center was started with anucleus of Langlg personnel, and now shares aportion of the development work in aeronauticsand space flight.

The cfshoot work at Wallops Island now is afullyiedged program which encompasses rocketvehicles and flight-test aircraft in a self-containedorganization.

The group that went to Muroc Dry Lake to htlpin the flight-test work on the Bell IS-1 grewinto the Right Research Center, formed aroundthe core of langlg people.In Houston, Texas, a complete new centerhas sprung up which almost dwarfs the otheroperation, of NASA. The Manned SpacecraftCenter, as it is now, originated as the Space TaskGroup at Langley.

Familiar names from the Langley personnel rostersdot the organization charts e these latercenters. Familiar techniques learned and develo,hedin the wind tunnels and other facilities at Langleyhave been extrapolated to solve the advancedproblems of space fiight. Familiar facilities whichonce tested scale models of unswept wings andpiston-engined aircraft now blast air at the latestshapes of lifting bodies for recovery of astronauts

from earth orbit.The progress of this decade has been built on thestrong foundations of the Langlg Research Center.

No one action triggered the explosive growthof space programs in the United Statesmore than the Russian launching of theSputnik I.Hardly a month passed after its successfulorbiting when President Dwight I). Eisen-hower announced the appointment of Dr..Jam. R. Killian, President of the Massa-chusetts Institute of Technology, as a vecialscience advisor to the White Hmse.This was followed by a Congressional in-vestigation of the U. S. missile and spaceprograms and the formation of specialcommittees in both houst 3 of CA:ingrmcharged with the rrsponsibility for spaceaffairs.The American R3cket Society and theNational Academy of Sciences joined inrecommending the creation of a NaticmalSpace Establishment.In January 1958, the Prcsident's State ofthe T:nion message to Congrms told of thecreation of the Achanced Research ProjectsAgency to gather together all of theanti-missile and satellite activities in theDepartment of Defense.Later that month, the Senate PreparednessInvmtigating Subcommittee submitted aunanimous report which asked for the crea-tion of an independent space agency andthe organizational overhaul of all missileand space programs in the Dept. of Defense.

dr,

At"

T he President'. Ad.ison Committee onGovernment hganization recommendefidim all non-militarv Tact-. activities bgathered together into a C iviIia n spaceagency. u5ing as its foundation the NationalAdvicorv Committee for Aeronantic5 Presi-dent Licenhower approved th:5; re-commen-dation on March 71 V4S11. and on April 2.19.V. sent hi5 hill for the estaHhou-:5! ofthe civilian aiZe9C% to the Congress.Between then and July Ih. CA:ingress de-veloped the legi5lat'on that wa5 to becomethe National Aeronautic; and Space Act of19)11. It was signed into law hv PresidentEicenhower.julv 2". 11.68.In part. Li5en1ow r r tatemcnt on thesignilig of the hill said:-.The present National ...1dvisor. Committeefor Aeronautics iNACA1 with it5 large andcompetent (tafT and well-equipped labor-atories .5 ill pros ide the mic leu5 for NASAThe coordination of 5pace explorationrespon5i.iilitir5 with NACX5 traditionalaeronautical research function5 i5 a naturalevolutionEisenhower norninated Dr. T. Keith Glennanto be the first Administrator of the new Na-tional Aeronautic5 and Space Adn 5trationand NACA Director Dr. Hugh L. Drydento lw the Deputy Admini5trator. Theirnomination5 were approved and confirmedlw Congres5; the appointee5 were sworn in

414.2.9

I. X-15 launch techniquewas investigated in theseven hv ten-foot windtunnel at Lancley witholve-twentiet hmodels.

2. X-11 model in Lantzleysupersonic tunnel.

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August 19, attended the last meeting ofNACA two days later, and on October Iopened thc new agency for business.There already had been evidence that thenatural evolution Eisenhower referred to inhis statement was no figure of speech. Be-fore the establishment of NASA, mannedsatellite programs had been considered byNACA scientists, and the work had gonefar enongh to recognize some of the prob-len-s of the re-entry of manned vehiclesfrom orbit. Three solutions had beenproposed: The ballistic capsule with heatshield. the hypersonic glider, and the liftingbody.Miring the years since the establishment ofNASA. Langley scientists hate continuedto make major contributions to the scienceoil space flight, to develop tinique testfacilities for better understanding of thenroblems. and to adapt existing test facilitiNto new 119eS.

NASA was assigned responsibility for theU. S. manned space flight program inAugust 1938. In its first week of existence,NASA organized the Space Task Group,and based it at Langley. It included 45scientist.s from the Langley and LewisResearrh Centers.Many of the Langley membeis of the SpaceTask Group staff were no strangers to theproblems of manned space flight. Beforethe Group was organized, they had de-velcped the concept of the "Little Joe" testvehicle, which became a workhorse of theMercury program; they had shown thefeasibility of a manned satellite program,using existing intetrontinental ballisticmiscsiles for launch vehicles and the ballisticre-entry shape as the crew capsule. Andthe contour couch conceptlater used inall the space capstil& crew positionshadbeen conceived and built at Langley, andtested to prove its feasibility.They had drafted the preliminary specifications for what was to become the Mercuryprogram in June 1958; when they wereappointed to the Space Task Group inAugust, they were ready to go.After that date, they designed the "Big Joe"test vehicle, proved the feasibility ofthe ablative heat-shield, and developedprocedure trainers for the Mercury astro-nauts which were the foundations for thecomplex simulators of later space flights.In support, Langley Research Center tookon the responsibility for pil.nning andcontracting for the Mercury trackingnetwork.Langley scientists developed supportingprograms for manned space flight such asProject Fire, which investigated the heat of

re-entry and its effects on materials;Project RAM (Radio AttenuationMeasuivinents) which focussed on theproblems of transmitting through the plasmasheath formed around a re-entering space-craft; and the development of infra-redsensors to tell a spacecraft which way wasup.The automatically inflating satellite, iikethe huge Echo balloon, was a Langley con-cept and development; so was the inflatablespace vehicle, which was one approach tothe problem of housing men in an orbitinglaboratory.Re-entry speeds as high as Mach 26 wereachieved in multistage rocket firings fromthe Wallops Station in a study of the prob-lems of that unique phase of space flight.The concept of rendezvous and the stagingof a space flight from an initial cstallishedorbit was studied by Langley scienti,:s whoestablished the value of the hinar-orbitrendezvous, which is the foundation of theentire Apollo program. and which made thcApollo program felsible with the availablesizes of launch vehicles and crew capsules.More recently, the highlt successful LunarOrbiter series of exploration satellites, de-signed to transmit topographic informationabout the lunar surface, was conceived atLangley and the development programmanaged by Langley scientists.Project Mercury grew into Project Apollo,in which the first announced goal wassimply to sustain an orbit around the earthor the moon with a multi-man crew. It waslater expanded to tackle the job of mannedlunar exploration, and Project Gemini wasestablished to solve some of the problems oforbital rendezvous and docking that wouldcharacterize the advanced phases of theApollo program.

This is properly a history of aviztion andthe developments and contributions of theLangley Research Center to the sciences ofaeronautics. But these contributions ofLang!ey to the space effort were summarizechere because they illustrate how the basicknowledge of aeronautics, acquired over theyears, has evolved into solutions to theproblems of space flight.

More than that, they show that Langleywas able to make major contributions tothe space programs while still maintainingits leadership in aeronautical research.The handling of such diverse programs asthe responsibility for a massive electronicnetwork for tracking a spacetraft in orbit,or the development of an inflatable spacevehicle, is a tribute to the organization ofthe Langley Research Centm

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These tasks were often under scientists whoworked on a space problem for one weekand then switched back to aeronauticaltasks or to re-entry physics. The work wasdone while the entire Langley staff wasoccupied with the problems of reorganiza-tion under NASA, with the pressure ofexpanding staff and facilities, and with theproblems of contracting for and monitoringor managing programs with outside industrialcontractors.The basic studies of supersonic cruise air-craft configurations that Langley had beenpursuing for some years began to pointtoward two major areas early in this decade.First of these was the multi-mission aircraft,a concept of a design that would be equallyefficient at high and low speeds, and athigh and low altitudes. This thinking ledultimately to the current form of thevariable-sweep wing.

1. Shock waves festoon asmall scale model of theX-15 in Langley's four-by four-foot supersonicpressure tunnel.

2. X-15 model in Langleysupersonic tunnel.

3. New ablative coatingfor X-15 ch;tnges plane'scolor from black towhite.

3

The other area was the development ofconfigurations for a supersonic transportwhich found application to the Boeingdesign chosen for development early thisyear.In support of both these programs, specificsolutions were found to many of the per-plexing problems of sustained supersonicflight. For example, the studies on air inlets,nozzles and exhaust configurations, madein the Langley tunnels, have been adaptedby industry to the designs of the latest mili-tary aircraft. Base drag studies, initiatedas part of the TFX (later F-111 develop-ment), made a major contribution in thedrag reduction program for that airplane.It took a while before the programs gotthis specific, however. In the early monthsof this decade, the work on variable-sweepwas almost entirely confined to comments,discussions and tests on the variable-sweep

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Swallow concept, devdoprd in Great Britain.Ttw Swallow concept was encouraged byLangley personnel who were asked tocomment, and became the initial basis fora proposal for a joint research program.The I 6-ft. transonic tunnel was to be usedfor some test? of the jet exits, and othertests, f -attiring a Langley-suggested modifi-cation of the Swallow, were to be made.Langley took on most of the job of con-structing the model and conducting thewind tunnel programs. The decompositionprocess of hydrogen peroxide was used tosimulate jet effects in the tunnel tests, andthe Langley model of the Swallow is re-membered today as one of the most complexever tested at the laboratory.For various reasons, the Swallow work wasdropped in favor of a configuration withengines in the fuselage, and tests were con-tinued to study the characteristics of variablegeometry.The tests that had been made on variable-sweep models indicated that they all suf-fered from major changes in stability as thewings were swept. This was the reason that

rt.

1. Modified Bell X-1model pioneered variable-

sweep studies in 1947.2. British "Swallow"

concept of variable-sweep was tested at

Langley.

3. Model of proposedmilitary supersonic

attack airplane shows wingsweep range.

thr Bell N:-.5 and I ;rumman NE101:- Iwings ,yere minslated forward as theywere swept aft.This wa5 a mechanical complexity thatNASA engineers believed they could dowithout, and their testing aimed towardthat goal, among others.Parallel analytical studies on span-loacfingdone at Langley showed that if the pivotpoints were moved outboard, instead ofbeing on the centerline, the stability varia-tion could be reduced considerably. Someexperi,nents were done on a model of thiskind of configuration and they prove'i thebasic idea. It was to be the key to thesuccess of the vari able-sweep idea.

The outboard pivot made it possible tosweep the wings through a large anglewithout any need for translation. Furthertests showed that supersonic cruise per-formance potential was practically as goodas the best design-point cruise configurationsdeveloped earlier. Mach number for Machnumber, there was little to choose frombetween the variable-sweep airplane withoutboard pivots, and the best fixed-wing

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(ithtri, And t.ttl till thrCl/Ja7t.:W.1(HW tild1C, 01.11 11.1d 111111 de-VrItyl'd to) that point I he. were Appliedt() the 1,11(ffit .1 NAVA! Aircraft %eighing70,000 lb. whi(h w t() he ( of doingthe combat air pat rol mission phis high-altinide attack, :Ind striKe mis-sions. The concept lf the multimissionaircraft seemed feasi: in the light of theavailable data On viriable sweep.The Navy airpLine, even though it was apaper design based on limited wind-tunneldata and a paper engine, showed so muchperformance potential that it completelyoutclassed any weapon system then beingbuilt or planned.The briefing was repeated for the staff ofthe Air Force Tactical Air Command Head-quarters,.just across Langley Field, andthey suggested that the general staff receivethe same briefing. This done, NASA teamspresented essentially the same material ina series of briefings to industry. They talkedto eight major aerospace contractors in lessthan one month, acquainting them with theconcept and summarizing thc research.

Before mid-August 1959 Langley received aletter stating that the Air Force Researchand Development Command was beingasked to "take a further more detai1ed lookat your variable-sweep design concept as apossible solution to Air Force requirements."

A second round of briefings, presenting somenew data, Nvas made to industry betweenSeptember 1959 and January 1960. Duringa Navy briefing, Langley scientists pointedout that thc full potential of the variable-sweep design would best be realized ifthere were a completely new turbofanengine around which to build the airframe.

Development work continued at an accel-erated pace, and began to center on therequirements of Tactical Air Command fora fighter with extremely high performanceat low altitude and the capability of ex-tremely long range. Langley developed aseries of design layouts, paralleling a similardesign study done by the Air Force. Thefour models were completely designed indetail of aerodynamic configurations; scalemodels were built in the Langley shops,tested at transonic speeds in the eight-foottransonic pressure tunnel, and the dataanalyzed and flown to the Air Force atWright Fieldall in the time of 13 days.It was called Project Hurry-Up, and itlived up to its name.

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Bra-hugs, a second phase flurry-Up-,more anah. WA, studies and tests followedrapidly. Free-flight test, were made with amodel of one of the Navy configurations inthe full-scale tunnel, in a pacemaking r-1jrinien iii the developme:It of varia ble-sweep aircraft. Sweep anglrs were variedfrom 25 deg. to 75 deg. during flight, andno extraordinary problems, either of stabilityor control, developed.This work, the requirements of the Navyand the Air Force, and the studies con-ducted by the military services and industryfinally coalesced in Febrwry 1961. Sccre-tary of Defense Robert S. McNan:araordered that the requirements of the Army,the Navy and the Air Force be combinedinto a tri-service tactical fighter.The detailed story of the TFX program, asit was first called, and its evolution into the

11 fighter design, has been t.o!d before.Langley's part in the program was piayedfrom the start, in the development of theconcept of variable-sweep that made themulti-mission aircraftof which the F-111was intended to be only one examplefeasible. Later Langley studies providedrefined design data and evaluations for themilitary and industry. Finally, Langleyengineers attacked specific problem areasin the chosen design even after prototypeshad been built and flown.The work continue; today, applied to otherstudies as well as to those relating to theF-111. Part of those other studies centeron the supersonic transport.Late in 1959, a team from Langley ResearchCenter summarized the technical status ofthe supersonic transport in a Washingtonbriefing for Lt. Gen. E. R. Quesada, thenthe head of the Federal Aviation Agency.The point in time of the presentation wasjust after a round of detailed briefings ofthe military and industry on the potentialof the variable-sweep concept. The intro-duction to the supersonic transport reportstated that ". .. if the mission involvedflight at only the design supersonic speedand crusing altitude, and if no emergenciesoccurred, intercontinental ranges of com-mercial interest and importance could bereadily achieved. The intermediate rangethrough which the airplane must performto reach its supersonic cruise speed andaltitude and to descend therefrom, how-ever, imposes problems that must be solved.The research status as of today indicatesthat: the proper solutions to thc off-designproblems can be provided through someform of airfrati* variable geometrysuchas variable sWedV---in combination withan advanced fan-type propulsion system.

l'hr present re.carch position is that nofundamental p.ohlrui alpe.irs v,itti regardto their otf-driign mulitunis that canniube solved by inicentratr(l (TWA IT 11 effort

This landmark report, published later asNASA Teel nical Note 1)--123, -The Super-sonic Tran.port A Technicalwent on tc discuss the performance, noise,structures and materials, loads, flying quali-ties, runway and ',raking requirements,traffic control and operations, variable-geomet:y designs a d possible arei-,s forperfor nance improvements.The presentation signaled the time to beginserious work on development and construc-tion of an SST. Within weeks the jointNASA-FAA program was well along, andwithin the year, the first contracts had beenlet for development of components for thepower plants, pinpointed as the pacingproblem in the SST program.As in the case of the F-111, Langley hasmade many contributions to the develop-ment of the U. S. supersonic transport.Langley scientists have advised on themultitude of problems, conducted theoreticaland expelimental analyses, tested modelsin tunnels statically and in free-flight. Butperhaps the major contribution of Langleyto the SST program was its so-called SCATseries of configuration studies.SCATwhich was an acronym standingfor Supersonic Commercial Air Transportstarted with program status at Langleysometime during 1962. Its purpose was todevelop a configuration that would meetthe unique requirements of a commercialSST over the anticipated performancerange from takeoff through climb, cruise,descent, holding and landing. One goal, forexample, was to develop a lift-drag ratiomuch greater than that of the B-70 atcruise. Other aims included the ability ofthe final configuration to operate at off-designconditions economically and efficiently.The Langley studies settled down into two I)

different approaches early in the program.One of these used a variable-sweep wing,and designated SCAT-15, it became oneof the foundation stones of the entire SSTprogram.The other was SCAT-4, a fixed-wing proposalthat carefully integrated wing, fuselage,engines and tail into a highly-swept, cam-bered and twisted aircraft design. Thepurpose was to minimize the wave drag dueto lift, and this approach produced somedesign ideas that were later extended toother aircraft schemes, but have yet to seeapplication to an actual design.By early 1963, four SCAT geometries had

Navy combat airpatrol aircraft tuteste0 :it Langley, sh vkstwo extreme,posit ionsof variable-sweep wing.

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1. Navy version of theF-111 variable-sweepfighter is surrounded byLangley test models ofthe basic fighter.2. Built to fly, this modelembodies all aerodynamicfeatures.3. F-111 dynamic modelin free-flight tests atLangley.

4. Wing sweep studieswere made at Langleyon this unpowered modelof the F-111.

iwen selected as worth r IrrsuIng furtherThey in .liuled the S(7AT-4 and sc.vr-I 5,joined by SCAT-lb, another variable-sweep proposal that evolved from theSCAT-15 work, and the SCAT-17, a fixeddelta-winged layout with a forward canardsurface. This latter version had beendeveloped at Amcs Research Center.Industry investigations of these four con -figurations, done under NASA study con-tracts, showed that the SCAT-I6 andSCAT-17 had the most favorable per-formance. They were to become the basisfor the two competing configurationsdeveloped by Boeing and Lockheed.There was a tremendous dividend paid bythe SCAT and related configuration-studyprograms. Theory and experiment pro-gressed side-by-side, with continuing feed-back from one to the other. Gradually thetheories were modified to allow for thereal-flow conditions. As the aerodynamicefficiency of each design began to improve,so did the ability to predict that efficiencyby theoretical means.

This narrowing of the different rs betweenthem,: and experiment, began to Niuld thecapabdity first, to optimize, mild then, topreeict, the aertxlvilarnic characteristics ofa wide range of aircraft.During 1964, this ability to predict per-formance wo.1 developed into a computerprogram. In application to the SS'I' designs,it became possible to predict thr airplanepolar diagram--a plot of the lift coefficientagainst the drag coefficientwithin anaccuracy of three percent. This aerodynamicrevolution meant that a series of configura-tions could he investigated in a fraction ofthe time it formerly took. Small changes indesign details could be worked into thecomputer program and their effects onoverall performance predicted within amatter of hours. It formerly took weeks.A further extension now makes it possibleto use the same computerized approach tocalculate the performance of a deflectedairplane, that is, one that is distorted dueto its response to the loads of maneuveringor of unsteady flow.Finally, the computer program can bemodified to produce an output whichgeometrically describes the airplane con-figuration under test. That output, con-verted to a punched tape, can be fed intotape-controlled machine tools to produce awind tunnel model of the configurationstudy, again within a matter of hours.But the cleanest of aerodynamic configura-tions with the minimum of wave drag stillwould produce a sonic boom. Langleyresearchers have been working on thatproblem in a variety of ways since the earlystages of the SST program.Their studies have been analytical andexperimental, as is customary with manyLangley programs. Measurements weremade of sonic boom intensities in fly-bysof supersonic aircraft, and the results com-pared to theory. Tiny wind tunnel models,smaller than a tie-tack airplane, were builtand tested in supersonic wind tunnels atLangley to determine the physical charac-teristics of the sonic boom and the parametersthat caused and changed its nature.Engineering ingenuity has made it possibleto fly the supersonic transport before it iseven built. The prototype Boeing 707-80,which had been utilized in the program ofboundary-layer control, was further modi-fied into a variable-stability airplane, whosehandling qualities could be varied tosimulate the approach and landing charac-teristics of the SST. Langley pilots flew themodified airplane in a series of tests toevaluate the parameters of the SST, andhave analyzed the data for industry.

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Three basic configurationsof supersonic transports

were developed atLangley:

1. SCAT-4

2. SCAT-153. SCAT-16

4. SCAT-15F, anadvanced concept for a

supersonic transport,was developed andtested at Langley.

5. Wind-tunnel andfree-flight modeLswere extensively

tested.3

4

"111(

A J..4. Alf II ithsstods.11,44 the proolems integrating thesupervOill' irsosport into exoting al- tr sawcontrol si,stemi, hal twell underw..n., forscx,er.,1 ).,earx 1 he ockpit umulatorl4xatc 1 at Lang le),, .Ind It 14 tied into theFAA's air trathc control umolator at theNational Far ExperimentalCenter, .Atlantic City, N.Ehr text program was planned tostud)! the arrival and departure operationsof a typical SST the SCAT-16 configura-tion was used to estai)lish the flight charac-teristics in and out of the John F. Kennedynternat ional A i rport .

Ex pe rienced professio nal a irl i ne pilot crewsfrom t nited Air Lines and Trans WorldAirlines flew the simulated missions, workingthe SST in through incoming and outboundflights during peak traffic conditions of 148operations per hour. These were pioneer-ing flights and they quickly delineated someof the immediate and long-term problemsof SST operation in terminal areas.Langley's longtime experience in structuresand materials played an important part inthe screening and selection of candidatematerials for the SST. The standard tech-niques of metal testing were used; specimenswere heated to the operating temperaturesof the Mach 3 transport, subjected to

t.4 uir t/ -.tate temper.ttlrel, Andtested at pet 1.14ils interv.I. 11rtrrmilint-thr drtrni)r..ituni ot phrucAl prove-mei

tther specimen., which h.3.1 been sublected14) the heating ries 0,pical of number w.tughts in 411 "NS were checked at roomtemperature for fatigue properties.

Some of the LangleN. research in subsonicarnxlynamics is concerned with the develop-ment of advanced configuration conceptsfor aircraft. This research could be aimedat another generation of subsonic trans-ports, for example, but would producecruise speeds higher than those of existingjet transports. For example, cruise speedsof Mach 0.98 appear theoretically feasible,compared to the current average cruisespeeds near or just below Mach 0.8.

One way of achieving this large performanceincrement appears to be through the use ofa supercritical airfoil. This idea uses anairfoil section which resembles a normal,but inverted airfoil, to which a trailing-edge slot has been added. By mixing high-energy air from the under surface of thewing with the lower energy stream on theupper surface, the slot keeps the boundarylayer attached to the wing and preventsthe sudden transonic drag rise due toboundary-layer separation.

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Visitors to Langley's Field Inspection in1964 we.e startled to see the originalBoeiT:g 707-80 prototype aircraft fly past,almost level in the air, at the phenomenallylow speed of about 80 knots. Normalapproach speeds on the transport are around130 knots.

The difference was made by a system ofboundary-layer control, another area ofsubsonic aerodynamic rescarch that Langleyhas been working for many years.Boundary-layer control, in one form oranother, has been around for many yearsand used, to a greater or lesser extent, inmany applications. But botindary-layercontrol, in its most promisitiq applications,depends on thc availability of large quan-tities of air which are injected parallel tothe wing surface or over the leading edge ofa flap, in order to maintain thc flow overthe surfacc and prevent boundary-layerseparation and loss of lift.That is essentially what has been done inthe Boeing 707-80 prototype.Air is ducted along the wings and biastedout of nozzles over the leading edges offlaps which are deflected as high as 70degrees. A secondary benefit results; be-cause the cngincs normally would be runat low power scttings for the approach, andbecause they trust be run at high powersfor operating the boundary-layer controlsystem, there is a surplus of thrust available

in the approach condition. The Boeing707-80 prototype used a thrust modulationsystem which gave fast and powerful glide-path control, and which was hooked intoan automatic speed-control system.This particular concept of boundary-layercontrol was developed and installed byBoeing on the prototype airplane. Theflight evaluations were conducted by Lang-ley pilots to evaluate and determine thehandling qualities of large aircraft workingin a powered-lift regime.Some Langley research, like that done forthe supersonic transport or the variable-sweep aircraft, paid off within a few yearsafter its initiation. Other research has takenmuch longer to make the transition fromthe proof of feasibility to application.

In this latter area is the work on gustalleviation. In almost any airplane, a smoothride is better than a rough ride. It's morecomfortable for the occupants, it's easier onthe structure, it increases the fatigue life ofthe airframe, andin the case of militaryaircraftit makes for a steadier weaponsplatform.There has long been an interest in gustalleviation at Langley; the first serious workin that area bears a 1950 date. The theoryof gust alleviation was explored by Langleyscientists, and expanded by them into anexperimental installation on a twin-enginedBeech C-45 light transport.

1. Boeing 707 prototypewas flight-tested atLangley to evaluate sys-tems for reducing takeoffand landing speeds anddistances.

2. Full-scale prototype ofXV-8A "Flecp", a flex-wing aircraft built byRyan, was "flown.' inthe full-scale Langleytunnel.

3. Transporting a SaturnS-1 booster on a modifiedDouglas C-1338 wasstudied in wind-tunneltests at Langley.

4. Newest heavy logisticstransport, Lockheed'sC-5A, undergoes mode:tests at Langley.

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The system workcd; it reduced the effectof gusts and provided a smoother ride forthe crew.The flight tests were reported in 1961 in aNASA Technical Note. The aviation in-dustry, which had been running someparallel studies, wrote parallel reports ongust alleviation systems for such diverseairplanes as the Cessna 310 and the NorthAmerican XB-70.The Air Force currently is funding a pro-gram, now nearing flight testing, to installand evaluate a gust-alleviation system on aBoeing B-52 airframe. The Air Force hopesto increase the airframe life of the large,flexible aircraft which it will be operatingby 70 to 100 percent.The technique is equally applicable tobusiness or personal aircraft, NASA scien-tists say, and the state of the technologywould permit those applications right now.Until the X-20 Dyna-Soar space glider wascancelled, the program was under the jointdevelopment cognizance of NASA and theU. S. Air Force. The Dyna-Soar was anextension of the research aircraft concept,and was intended to extend the range ofperformance from that of the X-15 on upto orbital velocities.

Vertol 76 tilt-wingVTOL aircraft was

evaluated at Langley using1. a free-flight model

and 2. the actualairplane.

3. British HawkerP.1127 V/STOL tacti-

cal fighter developmentaircraft, was flown at

Langley in the free-flight tunnel in model

form and in tests.

Much of the support work for the Dyna-Soar program was done at Langley, in-cluding tests with a free-flight model in thefull-scale tunnel to determine dynamicstability and control characteristics.Other Dyna-Soar technical support in-cluded the use of a radio-controlled dropmodel, launched from a helicopter; transonictests in the eight-foot tunnel on the com-bination of the Dyna-Soar glider and itslaunching vehicle; transonic stability andcontrol tests in the 16-ft. transonic tunnel.Hypersonic wind tunnel tests of the spaceglider were made in Langley's 11-inchhypersonic tunnel at a Mach number of9.6, to determine stability at low angles ofattack and to check the effects of nose andcanopy shapes on the stability.Dyna-Soar used a unique skid landing gearsystem, rather than conventional wheels,because any ordinary materials used fortires would melt in the heat of the re-entryprocess. The Dyna-Soar landing gear wastested on the landing loads track at Langley.Heat transfer measurements and fluttercharacteristics of the Dyna-Soar were otherproblem areas studied at Langley.Work on the Dyna-Soar and the X-15, plustheoretical studies conducted during recent

years, has pointed the way for researchon hypersonic vehicles with typical cruiseMach numbers of 7. At operational speedslike these, an aircraft would develop tem-peratures above 2,000F on the nose capand 1,600F on the leading edge of the wing.Basic work at Langley has concentrated inthree general areas of hypersonic cruisevehicle problems.First of these is the configuration study,where proposed shapes for the most effi-cient flight at Mach 7 are analyzed andlater tested in hypersonic wind tunnel..But given the extreme temperatures ofhypersonic cruise flight, unusual structuralconcepts must be developed to enable thevehicle to survive in one piece, and toprotect the occupants from excessivetemperatures.Langley has conceived some structuralapproaches to carry the loads, sustain thetempelatures, house the fuel and insulatethe passengers. One such structural conceptuses a thermos bottle effect. Liquid hydrogenfuel is contained inside one structure, anda second structure, the primary load carrier,is concentric with the inner tank structure.The outer shell, planned to sustain theprimary loads at the elevated temperatures

3

to be encountered, is made of a superalloy.The choice of materials, and the develop-ment of new ones for the job, is the thirdarea where Langley research studies aremaking positive contributions.

A major contribution to hypersonic pro-pulsion technology is expected from theflight-testing of a small hypersonic ramjetengine now being built for the LangleyResearch Center by the Garrett Corp. Itis &signed for operation between Mach3.0 and 8.0, and will be mounted on theX-15 research aircraft for in-flight tests.The engine is an axially symmetric type,18 in. in diameter, and is designed for aweight of 800 lb.

Langley guidelines for the design of theengine suggested a minimum number ofmoving parts in the engine itself, andemphasized the internal flow and theaerothermodynamics of the cycle. Neitherminimum drag nor optimum cooling wasrequested. Weight limitations demandedhighly refined structure, and the regenera-tive internal cooling is also highly refinedto us,.. a minimum amount of the liquidhydrogen fuel.Much of the pioneering work on the prob-lems of aerodynamically heated vehicles

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-..S"...

1. Lockheed XH-51A isflown in Langley studies

of hingeless rotor heli-copters.

2. Tri-service V/STOLtransport, the XC-142A,

was tested atLangley with

dynamic models.

3. Republic F-105fighter-bomber was

extensively tested inLangley tunnels.

has been done in the nine- by six-footthermal structures tunnel which has beenoperating at Langley since 1958. It dupli-cates the flight environment at speeds upto Mach 3 by using hot air in the test ,section.Recently a new facility, for structuralsimulation of flight at Mach 7, has beenoperated at Langley. Called the eight-toothigh-temperatures structures tunnel, its sizeand capability permits the testing of struc-tural concepts and complete componentsof hypersonic aircraft. It is the only facilityin the world able to do so, to NASA'sknowledge.At the opposite end of the speed spectrumfrom the hypersonic transport arc theV/STOL aircraft and helicopters. A majorprogram at Langley in recent years hasbeen the evaluation of handling qualitiesof the wide variety of these aircraft. Testvehicles and production aircraft alike havebeen assigned to the flight line at Langley,instrumented and flown through a seriesof test programs that gave new informationon the way these aircraft flew.In V/STOL, one of Langley's contribu-tions has been the concept of the tilt-winglayout which evolved into the tri-serviceV/STOL transport, the XC-142A.The first flying model of the tilt-wing con-cept, plus test work done with models inthe 17-foot low-speed wind tunnel demon-strated partial feasibility of the concept,confirmed that it could hover and couldmake the transition between vertical andhorizontal flight modes.The work broke into three phases: Windtunnel studies on a small scale with a varietyof configurations; large-scale research withbig models in such tunnels as the Ames 40-

x 80-ft. tunnel, and flight investigations inprototype or research aircraft.The flight test program on the Vertol 76,which was evaluated extensively and modi-fied at Langley, documented the handlingqualities, the approach and hover phasesof flight of this tilt-wing aircraft.When the tri-service transport requirementwas initiated, Langley moved into thc sup-port work for the aircraft development.Part of that work included free-flight testswith a one-ninth scale model, flown byremote control in the Langley full-scaletunnel. Complete transitions were madefrom hovering to forward flight in thetunnel to check the performance of thereal airplane.During the same time period, Langley wastesting the concept of the tilting-duct typeof VTOL aircraft, later exemplified bythe Bell X-22A developed for the Navy.Other VTOL work was done on the GE/

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1

I. Smokc defines vortexflow path over this

Langley model of ahypersonic cruise aircraft

in low-speed tests.

2. North AmericanX8-70 development

program was supportedwith wind-tunnel testsdone in many Langley

facilities.

Ryan XV-5A fan-in-wing VTOL aircraft,to determine the effects of tunnel walls andother restraints on the free-flight performanceof the models.Langley has acquired a Vertol twin-rotorhelicopter which has been modified to3erve as a variable-stability machine. Itis being put through a flight-test programto evaluate and define the control powerneeded for maneuvering heliccpters andVTOL aircraft of differing ch racteristics.Finally, Langley's concern with the day-to-day problems of aircraft have producedsome major contributions to current opera-tional safety. It was at Langley where thephenomenon of tire hydroplaning was firstanalyzed and evaluo' ed, and where itsdangers were first dAineated to the aircraftand automobile industries.The accuracy of aircraft instruments, par-

AM,

ticularly the altimeters available commer-cially today, is another problem area understudy at Langley. Related to that is theability of a pilot to maintain a constantflight level, either flying by hand or onautopilot, given the accuracies of today'sinstrumentation. That ability is an impor-tant factor in Langley studies of collisionprevention.

When a large aircraft lands at an airport,it leaves behind it, for a time up to a fewminutes, a turbulent vortex wake withsufficient energy to upset a small aircraftthat lands too soon after the big one. Themagnitude of these wakes and ways eitherto reduce or avoid them have been studiedat Langley.

Slush on the runway increases the takeoffdistance. Langley studies of the slush prob-

lem led to the current practice againsttakeoffs on runways where there is morethan one-half inch of slush.

The list could go on; the presence of Lang-ley research is almost everywhere in routineoperations of aircraft, developmental flighttest of experimental prototypes, or thedesign stages of new approaches to thefrontiers of flight.

The year now is 1967, fifty years after thefirst founding of the Langley laboratory ardthe beginnings of the first attempts tounderstand the problems of flight and,understanding them, to do something aboutthem.

The work of Langley men and women hasbeen the foundation on which much of thiscountry's aeronautical knowledge andstrength has been built.

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Fifty years is not a very long time in the recorded span of history.A man fifty years old today is still considered a young man, at the top

:5 of his potential. Today's generation of managers in tilt: aviation in-dustry were born about the time that Langley Research Center wasborr, and they grew Tp together.In their childhood, they watched the rare airplane that buzzed over-

.,head, maybe dropping leaflets or a daredevil suspended beneath agaudy parachute. They went out to the fairgrounds and saw aerialacrobatics, orin the ultimate thrilltook a ride over their hometown for five dollars.

i; In their teens, they hung around the airports, envying the suave pilotswith leather jackets who flew the biplanes and the new light mono-

s. planes that held the p :omise of a plane in every garage. They washed! airplanes, wiped windshields, poured gasoline in exchange for a ride

or for instruction.They went to work in the fledgling industry, or to college to study the

Li initial complexities of calculus so that they could someday design anairplane.

it Many of them went to war in the airpl -Ines they had helped to develop,ti in one way or anotlKtr, and too many of them died in those same

aircraft.I' In the postwar years, they struggled with the visions of any postwar

dreamer, hoping that at least some of the dreams would be realized.And that has happened. In their lifetime, the speed of airplanes ha;

tl gone from less than 100 miles per hour to more than 4,000 miles perhour. During their years, they have seen revolution after technical

11 revolution: jet propulsion, rocket flight, sweepback, variable sweep,supersonic flight, rotary-winged aircraft, vertical flight, guided missiles,manned spaceflight, unmanned exploration of the nioon and the planets.In their lifetime, the land masses and the oceans have shrunk to bemeasured now in hours instead of thousands of miles; to be spannedduring a meal and a nap, instead of during a week of steaming or atedious day of throbbing flight.And in the few months remaining between the time this is being written,and the time it is read, other aviation marks will be set. Recoids will bebroken and re-broken. New designs will take tangible form in thesolid structures of jigs and fixtures on factory floors.The extrapolations of aeronautical knowledge will continue to makepossible the exploration of space.These things will happen, because the thrust of development in Ivia-tion is upward into new regions of flight, and outward into new marketsand applications for the basic principles of flight,Those principles have been developed over the years by successivegenerations of scientists and engineers, pilots and mechanics, scholarlythinkers and backyard tinkererseven by fools and frauds. Theairplane today is the sum of many parts.But the largek of its parts is the fifty years of aeronautical researchpioneered and developed by the men and women of the LangleyResearch Center of the National Aeronautics and Space Administration.It has been fifty years since the first symbolic Thovels full of earth werelifted above the soil of Langley Field to signal the start of constructionof the first research laboratory of the National Advisory Committeefor Aeronautics.The men who turned the warm Virginia earth looked toward the sky.It was bright and sunnybut they saw the stars.

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