AD-756 861

STOL TRANSPORT THRUST REVERSER/VECTORING PROGRAM. VOLUME II

John E. Petit, et al

Boeing Company

Prepared for:

Air Force Aero Propulsion Laboratory

February 1973

DISTRIBUTED BY:

N d TMW Idwmam SmfeU. S. DEPARTMENT OF COMMERCE5285 Port Royal Road, Sp•ngfield Va. 22151

AFAPL-TR-72.109Volume II

STOL TRANSPORT THRUST RF.VERSER/VECTORING PROGRAM

Volume II

John E. PetitMichael B. Scholey

The APPM VICOMPANYD -

MAR .•1973

Technical Report AFAPL-TR-72*109, Volume 11February 1973

NATIONAL TECHNICALINFORMATION SERVICE

," j . I A 27)1 i

Approved for public release; distribution unlimited

Air Force Aewo Propulsion LaboratoryAir Force Systems Command

Wright-Patterson Air Force Base, Ohio

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981243FlPORT 'L L

STO-L Transport Thrust Reverser/Vectoring Pr-ogram, Volume.II

4 i-r ctit Iif? INO if *ý,r i..tv Fp. t i.iici'i he i

July 1971 - November 1972 Kina1emrjYplurnA 11A% , ftrl$ tittn?. tid,h,. iititij fsI ii01iflor

John E. Petit and Michael B. Scholey

December 1972 4-2on tC'0 T5IAr * 1-14 C.I.A.1 #'0 sit, OQIfG.NA tOA* GIf $t10VT i.,,M4 ISI

F33615-71-C-1850 Noneb PRtOjif c r ito

643A111' OTYNrII REPORT NOISI (Any other nurmbepa that may be aussiged

this re~port)

d AFAPL-TiR-72-109, Volume H1CO DIS T I WI ?ON S TA T PIEN t

Ii I~ iL 'i I AR,-ft N TIr 5 SPOPISO'4,NG M.ILI TAftV AC Yi VI T

riet'qits of illustrotionsin~ Air Force Aero Propulsion Laboratory/TBEthis document mn'y be bett~f %right- Patter~son AFB, Ohio 45433atudied on microfiche.

Design, studies wvere conducted of thrust reverser and thrust vectoring systems fur STOLtactical transports to evolve systems properly Integrated with the aircraft. The studiesin-.:uded configuration design, performance, and weight analyses of feasible thrust reverserand thralst vectoring concepts. Test plans were developed for static tests of the mostpromising concepts. Following Air Force approval of the teat plans, test model hardwarewere fabricated.

Model tests were conducted of 2) a fan thrust reverser that exhausts all of the fan flowthrough cascades installed in the upper 1800 sector of the nacelle, and 2)-an externaldeflector/target TJR/TV system that combheii4 the functions of thrust vectoring andreversing into a single mechanism. Scaling relationships were used to correct the datato full-scale performance, and data correlations were developed for the external/targetmodel as a function of geometric parameters and nozzle pressure ratio.

DD, NOV.1473__ _ _ _ _ _ _

Security Classification04 LINK A LINK 9 LINK C

KEY WORDS

ROLr WT ROL E T ROLE WT

Thrust Reverser

Thrust Vectoring.

Nozzles

Turbine- Engines

Transport Aircraft

Unclasgifti-dSecurit$ CIa•Is cat., I

STOL TRANSPORT THRUST REVERSER/VECTORING PROGRAM

VOLUME II

John E. Peti.

Michael B. Scholey

This document has been approved for publicrelease, its distribution is unlimited,

FOREWORD

This report was prepared by John E. Petit and Michael B.Scholey of the Research and Engineering Division, AerospaceGroup, The Boeing Company, Seattle, Washington. It is thesecond of a two-volume final report submitted underAir Force Contract F33615-71-C-1850, "STOL Transport ThrustReverser/Vectoring Program." Volume II covers work conductedduring Design and Model Testing, from July 1971 to October1972. Volume I covers work conducted during Part IA - DataReview and Analysis from July 1971 to April 1972. Thecontract was initiated under Project 643A, "Tactical AirliftTechnology," Task 63205F, "Flight Vehicle Subsystem Concepts"and was administered by the Air Force Aero PropulsionLaboratory with Captain J. W. Schuman, and Mr. R. J. Krabalas Project Engineers. Subcontract support was provided byPratt & Whitney Aircraft with H. Kozlowski as Program Manager.The final report was submitted to the Air Force in November1972.

The authors wish to acknowledge the following Boeing personnelfor their asgistance during the design and model testingphases of the contract: T. W. Wainwright, AirbreathingPropulsion; L. J. Kimes and R. L. Wilson, Propulsion Project;and K. Ikeda and W. J. Stamm, Prop *sion/Noise Laboratories.A special acknowledgement is due M. E. Brazier, Chief,Propulsion Technology, for his continuing interest andsignificant contributions made during the program.

This technical report has been reviewed arnd approved.

E. C. Si onDirector, Turbine Engine DivisionAir Force Aero-Propulsion

Laboratory

S• • e

TABLE OF CONTENTS

Page

1, INTRODUCTION AND SUMMARY I

II. PART IB - DESIGN 5

2.1 Task 2.1 - Conduct Design Studies

of TR/TV Concepts 5

2.1.1 Baseline Airplane Configuration 5

221.2 Engine Selection and Scaling 9

2.1.3 Baseline Nacelle Design 13

2.1.4 Thrust Reverser and Thrust Vectoring 31System Design Concepts

C 2.1.5 Fan Cascade Thrust Reverser Detailed 84 ,Design

2.2 Task 2.2 - Analyze Performance of 94TR/TV Systems

2.2.1 Externally Blown Flap Systems 96

2.2.2 Mechanical Flap and Vectored Thrust 96Systems

2.2.3 Upper Surface Blowing Systems 102

2.2.4 Conclusions 105

S2.3 Task 2.3 - Select Designs for 105Part IC

2.4 Task 2.4 - Test Plan Preparation 1072.5 Task 2.5 - Fabricate Hardware for 107

Part IC

III. PART IC - MODEL TESTING 108

3.1 Task 3.1 - Conduct Static Performance 108Test

3.1.1 Fan Cascade Thrust Reverser Model 108Tests

3.1.2 External Deflector/Target TR/TV 125Tests

3.1.3 Overwing Target Thrust Reverser 146Data Review

v Preceding pagqlank

TABLE OF CONTENTS (Continued)

3.2 Task 3.2 - Correct Data to Full 151Scale Performance

3.3 Task 3.3 - Correlate with Existing 166Model Data

IV. CONCLUSIONS AND RECOMMENDATIONS 175

4.1 Part IB - Design 175

4.2 Part IC - Model Testing 178

REFERENCES 180

vi

LIST OF ILLUSTRATIONS

FigureNumber .Title Pag

1 Baseline Airplane Configuration 953-258 7

2 Thrust vs. Mach Number 10STF 342D, 342B, and 344 Engines2500 ft, Standard Day Conditions

S3 Thrust vs. Mach Number 11

STF 342D, 342B, and 344 EnginesSea Level Static Conditions

4 STF 342 Scaling Characteristics 14

5 STF 344 Scaling Characteristics .5

6 Basi.c Nacelle Installation - BPR 3.0 19Engine, Unmixed Flow, 2-2541-PD-194

. 7 Basic Nacelle Installation - BPR 6.0 21Engine, Unmi-ed Flow, 2-2541-PD-198

8 Basic Nacelle Installation - BPR, 12.0 23Engine, Unmixed Flow, 2-2541-PD-193

9 Basic Nacelle Installation - BPR 3.0 25Engine, Mixed Flow, 2-2541-PD-200

10 Basic Nacelle Installation - BPR 6.0 27Engine, Mixed Flow, 2-2541-PD-199

( 11 Basic Nacelle Installation - BPR 3.0 29Engine, Mixed Flow (Double Pod)

12 Intake Geometry 32

13 Basic Nacelle Weight vs. Mass Flow 34

14 Thrust Reverser Flow Control 36Requirements

15 Effect of Primary Reverse Thrust Mode 38on Reverser Effectiveness h R)basic = 50%

vii

LIST OF ILLUSTRATIONS (Continued)

FigureNumber Title Page

16 Mixed Flow Thrust Reversal Options 39

17 STF 402 Reverser Mode 41

18 Effect of Engine Overspeed 42STF 402 Reverser Mode

19 STF 402 Part-Power Characteristics 43

20 Reverser Effectiveness 45STF 402 "Cycle Spoiling"

21 Fan/Primary Thrust Ratio 46Parametric Unmixed Flow Engine Results

22 Estimated Reverser Effectiveness for 47"Cycle Spoiling"

23 Landing Roll Distance,AA* .10 49

24 Landing Roll Distance,Alm .30 51

25 Landing Roll Distance,A4 .40 53

26 Effect of Vertical Force Component 56On Landing Roll Distance

27 Effect of Airplane Gross Weight on 57Landing Roll Distance

28 Thrust Reve:ser Concept BPR 6.0 Engine, 58Unmixed Flow, TR/TV-p,02

29 Thrust Reverser and EBF Concept BPR 6.0 59Engine, Mixed Flow, "'R/TV-PP-03

30 Clamshell Thrust Reverser ane EBF 61Concept, BPR 6.0 Mixed Flow Engine,TR/TV-PP-14

31 Translating Sleeve Thrust Reverser and 62EBF Concept BPR C.0 Mixed Flow Engine,TR/TV-PP-16

viii

LIST OF ILLUSTRATIONS (Continued)

FigureNumber TitlePe

32 Thrust Reverser/Thrust Vectoring 63Concept - BPR 3.0 Engine, Mixed FlowTR/TV-PP-03

33 Thrust Reversing/Thrust Vectoring System 65C Rotating Valve Selector ,2-2541-PD-211

34 External Deflector TR/TV Concept - BPR 676.0, Mixed Flow Engine, TR/TV-PP-19

35 Common Hinge External Deflector TR/TV 69C System

36 Thrust Reverser/Multibearing Thrust 71Vectoring Concept, BPR 6.0 Mixed FlowEngine, TR/TV-PP-06

C 37 Multibearing Thrust Reverser/Thrust 72Vectoring Concept, BPR 6.0 Mixed FlowEnitine, TR/TV-PP-13

38 Thrust Reverser/Lobster Tail Thrust 73Vectoring Concept, BPR 6.0 Mixed FlowEngine, TR/TV-PP-07

39 Thrust Reverser/Two Dimensional Thrust 75Vectoring Concept, BPR 6.0 Mixed FlowEngine, TR/TV-PP-08

S40 Thrust Reversing/Thrust Vectoring 76Rotating Nozzle Concept, BPR 6.0Engine, Unmixed Flow TR/TV-PP-10

41 Thrust Reverser/Multibearing Thrust 77Vectoring Concept, BPR 12.0 Engine,Unmixed Flow, TR/TV-PP-09

42 Thrust Reverser/Lobster Tail Thrust 78Vectoring Concept, BPR 12.0 EngineUnmixed Flow, TR/TV-PP-12

ix

LIST OF ILLUSTRATIONS (Continued)

FigureNumber Title

43 Effect of Vectoring Fan Flow, BPR 12.0 80

44 Dual Pod, External Deflector TR/TV 81Concept, BPR 3.0 Mixed Flow EngineTR/TV-PP-15

45 Overwing TR Concept, BPR 6.0 Engine, 82Unmixed Flow, TR/TV-PP-04

46 Overwing TR Concept, BPR 6.0 Engine, 83Mixed Flow, TR/TV-PP-18

47 Overwing Thrust Reverser Installation, 85LO-953-035

48 Fan Reverser, Upper 1800 Sector, 89BPR 6.0 Engine, Mixed Flow

49 Area Plot Fan Duct and/or Cascades 91vs. Blocker Door Opening

50 Bifold Blocker Door Concept 92

51 Alternate Bifold Blocker Door Concept 93

52 TR/TV Nacelle Weight vs. Mass Flow 95

53 Stability and Control Engine Location 103Envelope

54 Fan Cascade Reverser Ins 'allation 110Schematic

55 Fan Cascade Reverser Model Installation ill

56 Annular Duct and Cascade Geometry 112

57 Internal Duct Static Pressure Tap 114Locations

58 Fan Cascade Reverser Model -- Exit Total 115Pressure Rake Installation

x

LIST OF ILLUSTRATIONS (Continued)

F4.qureN-' •__ber Title Page

C"9 Fan Cascade Thrust Reverser Exit Total 116

Pressure Rake Installations

60 Fan Cascade Thrust Reverser, Reverser 117Efficiency, Corrected ReverserEfficiency

61 Fan Cascade Thrust Reverser Ve3ocity 118Coefficient

62 Fan Cascade Thrust Reverser Discharge 119Coefficient, Airflow Match

63 Duct Static Pressure Distribution 120PTAVG/P = 1.575

64 Cascade Exit Total Pressure Survey, 122Blocker Door Angle = 900

65 External Deflector TR/TV Model Installation 127Schematic

66 External Deflector Geometry, Vector Mode 129

57 External Deflector Geometry, Section A-A 130

68 External Deflector Geometry, Reverse Mode 131

69 External Deflector TR/TV Model 132S/D = 1.0. 0 = 70

70 External Deflector TR/TV Model 133S/D = 1.03 0 = 360

71 External Deflector Thrust Reverser Model 134

C 72 Vector Efficiency, nV, Airflow Match 136, Dn/D = 1.225, S/D = 1.033, Y/D = .50

73 Effect of Setback Ratio on Vector Efficiency 137and Airflow Match, D n/D = 1.0

xi

LIST OF ILLUSTRATIONS (Continued)

FigureNumber Title Page

74 Effect of Setback Ratio on Airflow 138Match D /D = 1.225, Y/D - .50n

75 Effect of Setback Ratio on Vector Efficiency 139Dn/D = 1.225, Y/D - .50n

76 Effect of Deflector Position on Airflow 140Match, P /P = 1.60

77 Effect of Deflector Position on Vector 141Efficiency, P T/P. = 1.60

78 Effect of Deflector Position on Effective 142Vector Angle

79 Effect of Entraace Mach Number on Corrected 143Vector Efficiency

80 Reverser Efficiency q, Airflow Match 144, D n/D - 1.225, S/D .03 (

81 Thrust Reverser Performance Characteristics 145

82 Overwing Target Thrust Reverser Model 147Schematic

83 Target Thrust Reverser Model, Front View 148

84 Target Thrust Reverser Model, Aft View 149

85 Reverser Efficiency Correlation 150

86 Primary Nozzle Airflow Match Data 152

87 Primary Nozzle Airflow Match Correlation 153

88 Fan Airflow Match Correlation 154

89 Scaling Effects of Reynclds Number on 1;6Velocity Coefficient

90 Comparison of Theoretical and Experimental 157Effects of Reynolds Number on VelocityCoefficient

xii

(

LIST OF ILLUSTRATIONS (Continued)

c FigureNumber Title Page

91 ASME Discharge Coefficient vs Thrust 158Reynolds Number

92 Comparison of Model and Full Scale Corrected 159Reverser Efficiency Data for a CascadeThrust Reverser

93 Comparison of Model and Full Scale Corrected 160Reverser Efficiency Data for the C-5A Fan

( Cascade Reverser

94 Comparison of Model and Full Scale Corrected 161Reverser Efficiency Data for a HemisphericalTarget Reverser

95 Comparison of Model and Full Scale Corrected 162Reverser Efficiency Data for a TargetThrust Reverser

96 Comparison of Model and Full Scale Corrected 163Reverser Efficiency Data for the 737 TargetThrust ReverserC

97 Comparison of Model and Full Scale Airflow 164Match Data for the 737 Target ThrustReverser

98 Comparison of Model and Full Scale Perform- 165{. ance for Spherical Eyeball Nozzle

99 Discharge Coefficient Correlation for Hinged 168External Deflector PT/P - 1.2

100 Discharge Coefficient Correlation of Hinged 169External Deflector Nozzle P /P" - 1.6

I01 Discharge Coefficient Correlation of Hinged 170External Deflector Nozzle PT/P = 2-2

102 Corrected Vector Efficiency Correlation for 171Hinged External Deflector Nozzles, PTIQP = 1.2

xiii

F-F~

LIST OF ILLUSTRATIONS (Continued)

FigureNumber Title

103 Corrected Vector Efficiency Correlation for 172Hinged External Deflector Nozzle, PT /1 = 1.6

104 Corrected Vector Efficiency Correlation for 173Hinged External Deflector Nozzles, P /P = 2.2

Ta

105 Comparison of Discharge Coefficient Ratio Data 174

Xlv

LIST OF TABLES

TableNumber Title Page

I Mixed Flow ST 34U2 Simulatiov 12Perform-ance Data

C II Installation Dimensions STF 342D Engine 16(BPR 3.0)

III Installation Dimensions STF 342B Engine 17S...(BPR 6.0)

t IV Installation Dimensions STF 344 Engine 18

(BPR 12.0)

V Baseline Nacelle Configurations 13

VI Baseline Engine and Nacelle Design 33Characteristics

VII Thrust Reverser Concept Evaluation for 37Externally Blown Flap Lift Systems

VIII Thrust Vectoring and Reversing Concept 99Evaluation for Mechanical Flap andVectored Thrust Lift Systems

IX Thrust Reverser Concept Evaluation for 104Upper Surface Blowing Lift Systems

SX Evaluation Summary 106

XI External Deflector Test Configurations 128

Xv

Lilt 'of lqomevwlature

ALT. - altitude

A8 - nozzle throat area

A - effective fan duct flow areaJD

A - effective fan duct flow area during mixedJD flow operation

AJE effective primary exhaust flow area

•* effective primary exhaust flow area duringmixed flow operation

BPR - engine bypass ratio

- mean chord length'I

Cv - nozzle velocity coefficient

CD - nozzle discharge coefficient

DRAW - intake ram dragD aWAT 2 (JDRAM• "g (m2

Fx - Axial thrust componentxIF lateral thrust component

y (IFz - vertical thrust component

FG - gross thrust

FNT - total net thrust

FNT u FGROSS - DRAM

FNDucT - fan duct net thrust

GW - gross weight

KTAS - true air speed, knots

LRD - landing roll distance

M - Mach number

xvi

List of Nomenclature (Co tinued)

N1 - low rotor speed

STS - turbine inlet temperature

V - freestream velocity

WAT - total engine mass flow rate

Greek Symbols

SI nR - reverser efficiency

nReff - reverser effeutivenessA - braking coefficient

eff - effective vector angle.0 eff = tanS) F

xS - airflow match

xt*

xvii

ME-E-F I ' - ----

SECTION I

INTRODUCTION AND SUMMARY

An essential requirement of military STOL tactical transportsplanned for the 1980 time ruriod will be to operate fromairfields of 2500 feet or less. These aircraft will usethrust reversers as primary braking devicee throughout the

( landing ground roll. Also, some STOL concepts will usethrust vectoring systems to help control the flight-pathof the airplane and reduce takeoff and landing speeds.Consequently, emphasis must be placed on designing efficientand reliable thrust reverser/vectoring systems to achievethe field length objective.

C Commercial jet aircraft have used thrust reversers assecondary braking devices since the beginning of theiroperation. However, the-complex problems caused by-theinteractions between reverser exhaust and aircraft flow-fields have limited their usefulness. These problems

L include exhaust gas recirculation which can lead to enginesurge, impingement of exhaust gases on the ground oradjacent aircraft surfaces, and engine mass flow matching.Also, the reverser flow can cause blanking out of aero-dynamic control surfaces leading to a loss in aircraftdirectional stability and cor..trol, buoyancy effects thatdecrease the efficiency of the ground braking systems,and changes in airplane drag. All of these problems havebeen experienced during the development of existing commer-cial aircraft. However, the availability of long runwayshas made it unnecessary to completely resolve the inter-actions between the reverser and aircraft flowfields.

To avoid the limitations of existing systems on future STOLaircraft, attention must be given to the following technicalareas:

o TR/TV performance0 Exhaust gas flowfieldo Aetc-dynamic interferenceo Engine operationo TR/TV system design including weights and structures

The above considerations have significant influence onnacelle placement, thrust reverser and vectoring systemgeometry, and operating envelope.

Preceding page blank

1<j

The Boeing Company, with subcontract support from Pratt &Whitney Aircraft, conducted an 18-month research programto study the above technical areas. The program was 0:administered by the Air Force Aero Propulsion Laboratory,Wright-Pitterson Air Force Base, Ohio. Program objectivesare:

1. To develop methods to predict thrust reverser andthrust vectoring system performance.

2. To establish design criteria for high efficiency,lightweight thrust reversers or thrust vectoringsystems for STOL aircraft.

The program has three parts: u

Part IA - Data Review and AnalysisPart IB - DesignPart IC - Model Testing

This volume of the report describes the results of Part IBand IC. Detailed results of Part IA are contained inVolume I.

Analyticil models for predicting TR and TV nozzle performanceand evaliating TR and TV influence on the total airplanesystem were developed during Part IA. Three computerprograms were developed to predict jet trajectory andspreading, reingestion, and TR and TV system performance.The models were developed using analysis and data correla-tions, based on the results of an extensive literaturesurvey. Supplemental static tests were conducted to filldata voids discovered in the literature.

Part IB consists of the following tasks:

Task 2.1 -- Conduct Design Studies of TR/TV SystemsTask 2.2 -- Analyze Performance of TR/TV SystemsTask 2.3 -- Select Designs for Part ICTask 2.4 -- Test Plan PreparationTask 2.5 -- Fabricate Hardware for Part IC

The objective was to conduct design studies of thrustreversers and thrAst vectoring systems for STOL tacticaltransport aircraft to evolve concepts that are properlyintegrated with the airplane. During Task 2.1, TR/TVconcepts were designed in sufficient depth to define theTR/TV system and nacelle geometry, formulate actuationrequirements, define materials, and allow performance

and weight estimates to be made. Three view layouts werecompleted for each system studied. The design studyevolved into studies of TR and TV systems for externallyblown flap (EBF), mechanical flap and vectored thrust(MF + VT), and upper surface blowing (USB) lift systemsfor STOL transports.

The TR and TV concepts were analyzed and evaluated duringTask 2.2 on the basis of TR and TV performance and weightwith the objective of obtaining the best TR/TV performancefor the lightest weight system. The impact of the TR/TVsystem on the aircraft aerodynamic characteristics wasalso included in the evaluation.

The following conclusions were made based on the evaluationresults for the TR/TV systems considered:

1. The thrust reverser system for externally blownflap lift systems will probably involve the useof a fan cascade thrust reverser.

C 2. Mechanical flap and vectored thrust lift systemscould use either

a. rotating nozzlesb. multibearing vectoring nozzlesc. external deflector/target thrust vectoring/

C reversing systems

depending on the type of engine cycle (mixed orunmixed flow).

The rotating nozzle vectoring system would beapplied to unmixed flow engines and would utilizethe rotating nozzles for thrust vectoring andthrust reversing. However, the required nacelleposition (forward of the wing leading edge) toavoid reingestion and exhaust flow/airframeinterference during reverse operation results inan adverse pitching moment during vectoringoperation. The external deflector/target TR/TVsystem would also pose pitching moment problemsbut to a lesser degree. Multibearing vectoringnozzle installations would present no pitchingmoment problems, because the installation allowsthe thrust vector to be placed nearer the airplanecenter of gravity. Combining the multibearingnozzle with a reverser system is difficult,primarily because of the weight of the separatethrust reverser and thrust vectoring systems.

3

The use of a fan reverser and "cycle spoiling" ofprimary thrust would minimize the weight of thereverser system but would result in lower reverser • Iperformance.

3. Upper surface blowing lift systems will utilize anexternal target thrubt reverser system installedwith a mixed flow engine.

On the basis of the concept performance evaluations, thefollowing TR/TV systems representing the various STOL liftsystems were considered for Part IC testst

1. Fan cascade thrust reverser system (EBF, MF+VT)2. External deflector/target TR/TV system (MF+VT)3. Multibearing vectoring nozzle (MF+VT)4. External target thrust reverser (USB)

Existing data was considered sufficient to define theperformance characteristics of the multibearing nozzleand external target thrust reverser systems. Therefore,test plans were prepared during Task 2.4 for static testingof the external deflector/target and fan caacade thrustreverser systems. Following Air Force approval of thetest plans, the test models were designed and fabricatedduring Task 2.5.

Part IC has three primary tasks:

Task 3.1 -- Conduct Static Performance TestsTask 3.2 -- Correct to Full Scale PerformanceTask 3.3 -- Correlate with Existing Data and Analytical

Models

The fan cascade reverser model and the external deflectorTR/TV model were tested during Task 3.1. Also, the existingdata for multibearing nozzles and overwing external targetthrust reversers were compiled and reviewed. Task 3.2consisted of correcting the scale model performance dataobtained during Task 3.1 to full scale performance. Thescaling method was also added to the TR and TV SystemPerformance Program, TEM-357 as an option. Data correlationswere developed during Task 3.3 for the external deflector/target TR/TV model performance. The correlations werecompared with correlations of other external deflectorthrust vectoring concepts developed during Part IA.

4

SECTION II(PART IB - DESIGN

The objective of Part lB - Design, was to conduct designstudies of thrust reversers and thrust vectoring systemsfor STOL tactical transport aircraft to evolve concepts tha)are properly integrated with the airplane. The studiesincluded:

o Configuration design of feasible TR and TVconcepts.

o Performance analysis.o Selection of TR and TV designs that meet the

design objectives.o Planning of static tests to establish the reverser

and vectoring characteristics of the concepts.o Fabrication of model hardware for Part 1C tests.

The following paragraphs discuss the results of Part lB.

2.1 Task 2.1---Conduct Design Studies of TR/TV Systems

2.1.1 Baseline Airplane Configuration

The thrust reverser and thrust vectoring nozzle design studieswere conducted using a baseline STOL transport airplane con-figuration to provide a basis on which to judge variations inTR/TV system performance and weight. The baseline configur-ation, designated Model 953-258 and shown in Figure 1, wasselected from a series of Boeing in-house STOL transportstudies, Reference 1. The 953-258 configuration meets themission requirements of a medium STOL transport.

The fuselage shape is dictated primarily by the cargo box,which is 138 inches wide by 135/148 inches high by 540 incheslong. The nose shape is a minimum drag fairing consistentwith crew station requirements. Similarly, the aft bodyshape is a minimum drag fairing consistent with aft body load-ing, air drop, and takeoff rotation requirements. The landinggear and fairing are configured to provide a minimum stowedfrontal area consistent with flotation and runway roughnessrequirements.

5

M ODEL.5305,AEROGYNAMIC O.TA I.•L.QVA LEVER SJUSPENS :4

S HOIZ TAIL VRT TAIL MAN 4 SOx200-2O TIRES

AREA FT2 ;450.0 3490 3000 NOSE 2 29x11.O.l0 TIRES

SPAN 107.70 37.33 17.33

ASPECT RATIO 80 40 1.0 C .O4BTISWEEP CA4 90. t0o 35* 131rv 135/14Irv 54O*L

DIHEDRAL 0, -4* -

INCIDENCE 2' *4W* - MOESIGN GROSS 135.000 L2

TAPER RATIO .3 .5 .8 DESIGN STOL 122.000 LBE ASSAtUAT MISIONTHICKNESS RATIO BODY SE .152 .13 .13 STOL PAYLOAD 28.000 LE,

.SS b/2 .132 .13 .13 OE.W 77.500 LBTIP .132 .13 .13 DESIGN GROSS 160.000 LE M

MAC F" 14.76 9.72 17.39 MAX. AYLOAD SOO Li CTOLI,VOLUME COEFFICIENT - IDS .11

•-FUEL VOLUM-E

C. POWER PLANT RESERVE TANKS 12.00 LS4 BY-PASS 30 TURBOFANS WITH THRUST REVERSERS 14.3XO LB THRUST TANK N3 I IQ300 LB

TAW NO 2 13900 LTOTAL 36.300 LE

CENTER SECTION 142900 LTOTAl. 51.200L

541

(.Zor 8-J

-19-

EMERGENCY EXIT 22x36 (BOTH SIDES)EMERGENCY EX Ox48 7

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____ _ _ ____ ___ _ ~FLAP SUPPORT FAIR\^,$-

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~RIALE C¶SERLE FAPSWING ACCESS HOLE (TYP)

I, ALERON %*28(AVG).C,:OO5

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FLAP SUPPORT FAIP' ,3! '

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12-2541-PD41641 1A1 ,T,•.2541P[.¶64 A-

Figure 1: GENERAL ARRANGEMENT, STOL TACTICAL TRANSPORT,

MODEL 953-258

7 (8 blank)

The high wing configuration provides adequate cargo loadingtruck bed height and minimizes adverse ground effect. Thewing has an aspect ratio of 8 and a quarter chord sweep angleof 10 degrees with a taper ratio of 0.3. Four nacelles aresingle-pod-mounted located to minimize wing-nacelle draginterference and flutter penalties. The wing area was deter-mined by field length requirements, lift system capability, anddeployment-mission fuel volume requirements.

( The vertical tail is sized to provide adequate stability andcontrol. It is equipped with a serially hinged rudder formaximum effectiveness. The horizontal tail is also sized toprovide adequate stability and control. It is located on topof the vertical tail to minimize the required tail size andweitht. This location also provides an end plate effect that

I helps to reduce the vertical tail size and weight.

2.1.2 Engine Selection and Scaling

The design study used engine performance and design data pro-vided by Pratt & Whitney Aircraft STOL transport study engines.

C A review of the available study engines showed that the STF 342series (Reference 2) and the STF 344 (Reference 3), coveredthe range of bypass ratios from 3.0 to 12.0 and provides aconsistent level of technology. The component technologiesof these engines is characteristic of the generation ofhigh bypass ratio turbofans which will be entering service

( in the 1975-1980 time period. Although the study was ori-ginally intended to include bypass ratio 2.0 turbofans, theseengines will adequately cover the bypass ratio range currentlybeing ccnsidered for medium STOL transport aircraft. Also,it is expected that the results of the design studies may beextrapolated to bypass ratio 2.0 if required. The study

C engines are listed below:

Bypass Ratio Engine Designation

3.0 STF 342D6.0 STF 342B

12.0 STF 344

The study engines are dual rotor, unaugmented axial flowturbofans designed to operate with separate exhaust nozzles.Sincethis study includes mixed flow systems as well as un-mixed flow systems, mixed flow engine data was required. Thisdata was obtained by simulating mixed flow in the STF 342Dand STF 342B engines on a Boeing parametric engine performancecomputer program. (Reference 4).

Engine performance data for the STF 342 and 344 engines areshown in Figures 2 and 3. The results of the mixed flowSTF 342 simulation are shown in Table I.

9

IP&WA TOM-2190 REF 3

P>P&WA TDM.2177 REF 2MODIFIED TO HAVE SIMILARLAPSE RATE AS TDM-2190

24

ALT, 2500 FTSTANDARD DAY

22

20

I-

w STIF 342D IBMf 3.0)z.18 16

STP 3423 WSP W.)~

14

12 -STF 36A fPR 42M

DESIGN POINT

10 FOftSCALINS 0.--0 0.1 0.2 0.3 0.4 0.5 0.6

MACH NUMBER " Mo

Figure 2: TOTAL NET THRUST VS MACH STF 344, 3428, 342D - 2500 FT.

10

SP&WA TDM-2190 REF 3

P&WA TDM-2177 REF 2MODIFIED TO HAVE SIMILARLAPSE RATE AS TDM-2190

24 SEA LEVELSTANDARD DAY

22-

20

I 18 - STF 342D (BPR 3.0) .

I-j

16- STF 342BPR I.0

(. o-

14__ _ _ _ __ _ _ _

SSTF 344 (BPR 12.0) •>

12

10 ......0 0.1 0.2 0.3 0.4 0.5 0.6

MACH NUMBER - Mo

f Figure 3: TOTAL NET THRUST VS MACH NO. STF 344,3428, 342D - SEA LEVEL

11

TABLE • -

STF 342 MIXED FLOW SIMULATION*

T AFLATA8BPR ALT MN (ib) (1b/sec) .(Ft 2

STF 342D 3.0 0 0 14200 352. 4.955

STF 342B 6.0 0 0 14625 486.7 8.034

I.

*PRODUCES 12100 lb TOTAL NET THRUST AT

70 KTS, 2500 Ft, 930F DAY.

12

Scaling data was provided by Pratt & Whitney Aircraft toscale the engines to the required thrust size for the Model953-258 baseline airplane,-Figures 4 and 5. The scaling rule

L •selected was to provide the thrust required f~r operation at93*F, 2500 ft altitude, and 70 knots. This equates to the de-sign point thrust of the engines on tho baseline airplane. Theresulting scaled engine thrust, weight and dimensions areshown in Tables II, III, and IV for the STF 342D, STF 342B,and &TF 344 engines respectively.

2.1.3 Baseline Nacelle Design

The baseline nacelle designs provide a basis to evaluatenacelle weight and performance with the thrust reverser andthrust vectoring systems installed. Bapcline nacelle config-urations were developed for the variou4 engines and engine podinstallations to be considered in the study. The followingtable summarizes the basic nacelles used in the design studies:

NACELLE CONFIGURATIONS BYPASS RATIO

3.0 6012.0Single pod, unmixed flow Fig. 6 Fig. 7 Fig. 8

Single pod, mixed flow Fig. 9 Fig. 10Double pod, unmixed flow Fig, 11CI

TABLE V BASELINE NACELLE CONFIGURATIONS

The basic nacelles are designed in sufficient detail to definethe intake, nacelle contours, cruise nozzle design, engineaccessories, and engine mounting arrangement.

The following design criterion was used to establish intakegeometry:

1. The intake was sized to pass the engine design airflowat oea level takeoff thrust power setting.

2. The intake throat airflow per unit area is 0.289lb/sec/in2 .

3. The enmine face airflow per unit area is 0.292 lb/sec/in.4. The intake highlight to throat area ratio, Ahl/Ath'

is 1.30.5. The cowl exit radius, RE, is greater than 4.0 times

the throat radius.6. The intake diffuser half angle, S/2, is less than 50.7. The intake lip radius is 5% of the highlight radius.8. External geometry established by an assumed cowl

thickness of 5.00 inches at the fan face.

13

1.3 --

P&WA STOL TURBOFAN1.2 STF 342SERIES

1.1 -S'I-F 342D_ PR3.0 - _. (.cc S• 1,030 L, SLTo/

S0.8

w

0.-

wc-

0.7

0.6

0.5 0.6 0.7 0.8 0.9 19 1.1 1.2

RELATIVE ENGINE THRUST SIZE AT SEA LEVEL STATIC (

Figure 4: STF 342 SCALING CHARACTERISTICS

14

P&WA STOL TURBOFAN1.3 STF 344 BPR 12.01.3-

U

1.2 -

I_ _

f.1.1STF 344U. 14,926 LB SLTO .

S1.0

0.9

L L-J

0.7

0.6

0.5 0.6 0.7 0.8 0.9 1.0 1.112

RELATIVE ENGINE THRUST SIZE Ar" SEA LEVEL STATIC

•,Figure 5: STF 344 SCA LING CHA RA CTERISTICS

15

•J • •. m m•• un m zim • m , m w•=

4-U

Table II: INSTALLATION DIMENSIONS - STF 342D ENGINE (BPR 31O)

C

ro, Rouar Mount

(ThrhtuMunt

_T-

Die..

T-B E

FrontnViewlntla~o iesin o TF 342D DPi.e.~n cae rmBsc2300LsST hrs o1,3 b

Dimnsont Vinews BaiSnine ViaewFco cldEgn

SITO Thrust Lbs 23,000 0.610 14,030Weight Lbs 3,310 115W0 1.966Primary Exit Area Ft2 2.48 0.6110 1..51Fan Exit Area Ft2 US 0.610 2.51

A 34. 074 25.

C 95.3 11830 79.1

D 23.6 11830 19.6E 34.5 01830 28.6F 52.1 0.74 38.3

H ... 2L.-0.745 17.7____________ 35.1 11745 26.1

K 24.6 AW20.4

M 118.2 0.745 13.6N 12.3 0.745 13.6p 8.75 0.4 6,ER 23.6 flea.... 19.6 --

S47.3 0.83 39.2T 15.3 0.745 11.4U W04 0,W13.6

16

[w

U FTable/I/ INSTA LLA TION DIMENSIONS, STF 3428 ENGINE (BPR 6.0)

C s

Front Mount Ftgs DG ---

(-Th U 4: Front Mt. (Thrust Mount)"-F (~Thrust) i

Front ViewSieVw

(" Installation Dimensions for STF 342B BPR 6.0 Engine Scaled from Basic 23.000 Lbs SLTO Thrust to 14,490 LbsSLTO Thrust (Equivalent to 12,100 Lbs Thrust @ 2500 Ft, 93°~F, 70 Ktb, 100% Ram Recovery, No Bleed orPower Extraction).

Parameter or Basic Engine Scale Factor Scaled EngineDimension (Inchs)

SSLTO Thrust Lbs 23,0(X1 0.630 14,490

Weliht Lbs 3,230 0.620 2,003Primary Exit Area Ft 2.63 0.630 1.66Fan Exit Area Ft 2 9.79 0.630 6.17

A 38.8 0.764 29.6

(. B 85.4 0.764 50.0C 89.0 0.842 74.9

D 20.5 0.642 17.3

E 39.8 0.842 33.5

F 59.7 0.764 45.6

4. G 64.0 0.842 53.9

H 22.3 0.764 17.0

I _____________ 34.9 0.764 26.7

J 0 0.764I 0K 21.5 .4 18.1

(.L 67.8 0.764 51.8M 18.0 __ 0.764 13.7N 12.1 0.764 9.2P 11.86 0.764 9.06R 18.5 0.842 15.6

I l S 37.0 0.842 31. 4

T ___ 14.9 0.764 11.4

U Exit 14.3 0.842 12.0

17

Table I V: INSTALLA TION DIMENSIONS - STF 344 ENGINE (BPR 72.0)

C

Front Mount Fotp

C, Frot Mt.(Thrust Mount)

Powe ExrctoE

Dimesion(Inces) asicEngine SaeFco cldEgnsiro~~~~Dil Thut Lbi000 .461.2

Wei~ Lbs 3,30 0.42. ,50

FanO Exiut ArEqialn Ft2 15.107 cTruise 0 20t,90,70 ts 100%~ Ro eern Bedo

CLT 8hus9.230,0 0.915 81.,965Degh 24.3306 11915 22.01

Frmr xtAe t 72.60 T 0.746 62.80T

&37.0 Cr865 15.46 Cus

FnEitAe 2 30.50 0.786 826 -.38

A 45.80 0.865 3.624

D 25.06 0.915 22.03

F 75.65 0.866 65.80

G 81.54 0.918 63

.. .. 1

' I

A-A

FRONTMT REAR

(1HMST) MT

5501--

'>lip-

L 4GINZ: PI•AA STF 342D ENGINE TYPE PER P&*A REPORT

TOM2117 DAITED V11169 SCALED FROM SAS IC 23.000 POuD

StSTO'•THRU.T TO PROVIDE 14.030 POUNDS TAKEOFF THRUST tLAT RATEDTO"9 ECREES FAT SEA LEVEL.

SL001TRUST 14.00 POUNDSWEIGHT IND DUCTI I.91M1 POUNDS

PRIMARY NOZZLE EXIT AREA 1. 1 FL2

FAN NOZ EXIT AREA 3.53 FL

2. AIR INTAKE DESIGN AEQUIRE.MTS:THROAT MACH NO. °O. 0.AT SLSTO THRUST DESIGNAIRFLOW 3" POUNOSISECONDNIGHLIGHT AREA/TNROAT AREA • I.

EtFFETIVE ,'? . S' (ANGLE FROM THROAT TO COMPRESSOR FACENIASURED ALONG A STRAIGHT LIE)

I. REMVSER SYSMitS: TO BE DEVELOPED ON DETAIL CRAVdINGS.

NOZZLES SHOW3 IN TAKEOFF POSITION.

4. COM OF GRAVITY LOCATION SHOWN IS FOR BASIC DRY ENGINE

MIEII ONLY, AND DOES NOT INCLUDE INTAKE. COVILING. EXHAUST

NOZZle. OR AIRFRANE ACCESSORIES.

I PRIMARY NOZZLE TOATTAIL CHORO ANGLE 60.PLUG NOZZLE HALF ANGLE 150, COWK. EXIT HALF ANGLE 8!

SIN INCHES

--- - IC NACELLE INSTL -Figure 6: BASIC NACELLE INSTALLATION - FLOW

BPR 3 ENGINE SINGLE POD, UNMIXED FLOW ,- 1P0- •.

19 (20 blank)

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L S0•1CE PIWA SF 321 INGINE TYPE PER PWA REPORT TOM 117?amyO AWo SkCAa HRo SASIC 23. a POUND SLSTO THRUSTTO 4RVIK 14.4010 POUNDS TAKEOFF THRUST FIAT RATED To 93KiORl S FAT SEA M ILEAV

-SLSTOINR.JST 14.44 POUNDSO-

WOW ffe603cm) 2.003POUNDS5PIIARYNOMEKIT ARIA LWIN

WANNOMILI~E•AM E o IR

L. Alt INTAKE DEIGN REQUIRDAETmDoAimAC-NNo. * 0.111AT SISTO THRUSTMSI0N 41tNW 41 POUNOSISECOND

HNIOITJFAREAfl"OT AREA -*

UTW4ý2 - -9iANQI Rmw TroAT TO COMP'RESSOR FACEMEASURD SALONO A STRAIGHT LINE)

I SIR-SYSlMOS 1 K DEVELOPED ON DETAIL DRAWINGS.NOZUlES 110 INTAKEDFF POSITION.

4. C9111110FOAiIlYLOCAT11ONSHOWNISPFOR SASIC DRY ENGINE

MIGHT ONLY. AND DOES NOT ICWOUDE INTAKE. COWLING. IXHAUSTNOZZlS. 01 AIMIRAI4 ACCESSORIES.

5A PRIMORYNOZZUIIOATTAIL CIOD ANGLE 6*

""+I,4 •AYANQU[ - IP

B-B

0 v2 m m 5o

SCALE IN INCHES

---- 0ASiC '*ACES--E "STLOP -'0 S '4',LE PC:

Figure7: BASIC NACELLE INSTALLATION - -U%_,xi_ _ __..

BPR 6 ENGINE SINGLE POD, UNMIXED FLOW Ole

(22 blank)

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SFm1 ENAGLINEM

-Figure 8: BASIC NA CA LE INSTA LLA TION- SNSL POOBPR 12 ENGINE SINGLE POD

23 (24 blank)

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N I

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- - --- --

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CA-A

--- ,

NO0ESt

L MOI4LF P&WA STF ]D0 ENGINE TYPE P P&WA REPORT TOM-21T7

DAMES 40I14 SCALED FROM SASIC 23.00 POUND SLSTO THRUST

TO PROVIDE 14.030 POUNDS TAKEOFF TH4RUST FLAT RATED TO 13DU1S I AT SEA LEVEL.

SlWGHTO NhoT . 14t 1 POUNDSI6ET IIODOUCTSI 1,LIIIOUNOS

NOIXIO ITARIA &.04 F'T2

2. All INTAKE DESIGN RE•UIPI.UDiTS:

rTIROATMACH NO. • 0.60 AT SLSTO 14RUST

MI@51 AIRFLOW 355 POUNDSISECO1O

HICLIGIaTAREA/NHROATAREA * LX

MUITIW8 LI2 * SANGLE MIRO 11ROA1TO COMPRESSOR FACEMEASURED ALONG A STRAIGHT LIND

I. KVSi•WM SYST1 S: TOIKEDVEWQPEONDETAILORAWINGS.

NOZZLES SHORN IN TAKEOFF POSITION.

4 OCO AVITY LOCATION SHOWT IS FOR BASIC DRY ENGINE

MISIW ONLY. AND DOES NO INCUWDE INTAKE, COWLING. EXHAUSTNOZZLES. OR AIRFRAIE ACCESSORIES.

S. 0O=U[IOATTAILCNORDANCGIE - *

PIUGNAIFDIEU IS'

ORIXITIMALFNIUE • B.

B-B 0 12.3 . .50SCALK IN iN S

~~~GPI3 E.%C4GSa'G4E POO,Figure9: BASIC NACELLE INSTALLATION - 0-V X .cw

BPR 3 ENGINE SINGLE POD, MIXED FLOW "I54 20

25f (26 blank)

,,4

-~I/ 1 1 . :

I ,

fly

: I! I

STRUT CONTOUJR

A-A

c-c

NaMIL ENGINE: PWA 4TF 342B EiGINE TYPE PER P401% REPORT TDM-21T?

DAID4111i0 SCALED FROM BASIC 23.00 COND SLSTO THRUST

TO PROVIDE 14.490 POUNDS TAKEOFF THRUST FLAT RATED TO 93

DE-GCIS F AT SEA LEVELS.LSTO THRUST 14.410 POUNDS

WEIGHT IND DUCoSI 2, M3 POUNDS

NOZZE EXIT AREA 7.t3 2

L. AIR INTAKE DESIG4 REQUIREMDiTS:

THROAT MACH NO. * 0. 60 AT SLSTO THRUST

DESIGN AIRFLOW 41 POUNCSISEC•DHIGHLIGMTAREAITHlROAT AREA * 01)

VIFECTIV0 .1 - L* IANGLE FROM THROAT TO COIPRESSOR FACEMEASURED ALONG A S..AIGHT LINE)

I REVERIER SYSTIEMSi TO BE DEVELOPED ON DETAIL ORAWINGS.

NOZZLES SHOWN IN TAKEOFF POSITION.

4. CE1EROF GRAVITYLOCATION SHOWN IS FOR BASIC DRY OEGINE

MIGHT ONLY. AND DOES NOT INCLUOE INTAKE. COWLING. EXHAUSTNOZZLES, OR AIRFRAME ACCESSORIES.

I. NOZZ1LEIOATTAILCHORDANGILE *B

P.UGAWI ApNGLE • 13CMIITHALF41GLIE 8*

SCALE IN INCHET.S

Fifu-e 10: BASIC NACELLE INSTALLATION -.BPR 6 ENGINE SINGLE POD, MIXED FLOW -C.-O2-2541-P0-

:7 (28 blank)

zi A

ilia;

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PAea ~STA STA7 STA STA STA * PAioTo 158.7\ 188. 2 200O~ 2200 24PO

STA 618*~PTA 61.9

RgINACELLE j-.

THIXAT .... ;:4HKILlt (STA 819)

STA 618

FRONT VIEWT~4

_____ ____ IL ----- --- -- -

SIEVE

A STA ' STA STA220.0 2400 256.1

'NOTES:'L EGINE P&WA STF 34D ENC iNE TYPE PER P&WA REPORT TOM-2177-ATED 4111|M1 SCALED FRO BASIC 23.000 POUND SLSTO THRUST

TO PROVIDE K4,OD POUND TAKEOFF THRUST FLAT RATED TO 93

.-- � -_KOM FGRES FAT SEA LEVEL

SLSTO THRUST 14030 POUNDS

-STA 158.7 WEIGHT #40 CUCT) L110 POUDS- STA 186 2 NOZZLE EXIT AREA L04F2

-STA 2000""'- L2. AIR INTAKE DESI' N REQUIREMENTS:

-- STA 2200 THROATMACHON . • 0.60ATSLSTOTHRUST'- D,;SIG \ -STA 2400 lIOAINFLOW 355 POUNDSISECOND

HIGGLIRfTARE/TNHROATAREA * 1.30---- _ - _F ECTI|W11/' - $*(ANGLE FROM THROAT TO COMPRESSOR FACE

MEASWD ALONG A STRAIGHT LINE

3. REMERSER Y•Y1EMS; TO SE DEVELOPED ON DETAIL DRAWINGS.

NOZZLES SOIN IN TAKEOFF POSITION.

4. CEWR OF GRAVITY LOCATION SHOWN IS FOR $AS IC DRY ENGINEINEIGHT (ONLY, AND DOES NOT INCLUDE INTAKE, COWLING. OCHAUST

A VIEW WN5., OR AIRFRAME ACCESSORIES.S. NC".IROATTAILCHORDANGLE * 6*

PLUGNALFANGLE - 151

COWL.EXIT HALFANGLE • 9*

Q 19 20O 30 40 50"SCAE IN INCHES

"I I ... rgdJNO.p.BASIC NACELLE INSTL--- i Rl 3 ENG. DOUBLE POO

Figure 11: BASIC NACELLE INSTALLATION - P•_ FLOW

BPR 3 ENGINE, DOUPLE POD, MIXED FLOW " -01

I.9 (30 blank)

The resulting intake designs for each nacelle are shown InFigure 12.

The nacelle structure consists of aluminum sheet exteriorattached to conventional "Z" shaped stiffening rings. Thestiffening rings are secured to acoustically treated honeycombpanels on the inside surfaces. Engine loads are distributedbetween front and rear-engine mounts. On the unmixed flow

C engines the front mount carries vertical, side, and thrustforces. The rear mount carries vertical, side, and torsionloads. For the mixed flow nacelle configurations the loaddistribution is the same except the torsional loads arecarried by the front mount. Engine accessories and gear boxare located on the lower side of the engine fan case for

C engine maintenance and safety considerations.

The exhaust nozzles are designed to provide maximum thrustminus boattail drag consistent with the nacelle maximumdiameter and nozzle flow area. The plug nozzles wereselected for the baseline nacelles because instal 'tions

•C utilizing convergent nozzles would have excessive niacelledrag due to steep boattail angles.

A summary of the baseline engine and nacelle design char-acteristics are shown in Table VI, including weight estimates.The weight estimates are accurate to ± 10 percent and do notinclude weight required for a quiet nacelle installation orflutter. The range of weights for the basic nacelle config-urations are shown in Figure 13.

2.1.4 Thrust Reverser and Thrust Vectoring System Design( Concepts

The design study was conducted in sufficient depth to:

1. define the fundamental geometry required.2. define the fundamental requirements of the TR/TV

( nacelle installation on the baseline airplaneconfiguration.

3. formulate the basic requirements for the actuationmechanisms, actuators and systems.

4. define materials selection.5. allow estimates of TR or TV internal performance,

weights, and aerodynamic effects to be made.

The design study resulted in three view layouts of each systemwith 2ufficient detail to define internal and external nacellecontours and accessories locations.

31

Cl

-0 .ORHL R

5.00'ELLIPSE

I LRTH IE120)

THROA RAD US RT 125 170

SP NN R R DIUES IO 6.51 9.01.4

334

Iw

L4Uz 0 0

C z Z

w j 0 0

z

wa LU IGSNI 3HJ. NO S13NVd

0 CC 3MiV VH1 SONI ONIN3JdIISa(3dVHS,,Z,,1VNI±A1Z N3ANO3 01 cI3H3V±1V 1OWI13X3 .L33HS VfNiwnifv

IAJWZ w W<02.W5

I' 0

0 1 tw ;LU0 cc mC0r cJuCz -j c

Lus cL e

0. 00

z0 0.J0 00 P :,i'm 2~ Z

re0.(X0 CDr3N

-L 0U -9 w 0C

0 0) 0)w

I z z

C)C

33

0

.o

STF 342D STF 342B STF 344BPR 3.0 BPR 6.0 BPR 12.0

MIXED FLOW -NACELLE

NACELAEELLE

'4

oI I

200 400 600 800 U;

MASS FLOW W LB/SEC

Figure 73: BASIC NACELLE WEIGHT" VS MAS5/:LOW

34

It was recognized early in the study that the aircraft high liftsystem would have a strong influence on the TR or TV systemdesign. Consequently, the design study evolved into studies ofTR and TV systems for the following lift systems for STOLtransports:

1. externally blown flap (EBF)2. mechanical flap + vectored thrust (MF + VT)3. upper surface blowing (USB)

The various TR and TV systems for the high lift systems arediscussed in the following sections.

2.1.4.1 Flow Directional Control for STOL Transport ThrustReverser Systems

STOL transports will operate on short, unimproved runways andwill require thrust reversers as primary braking systems. Land-ing roll studies have shown that the reverser cutoff velocity,i.e. the velocity at which the engine must be shut down duringreverse mode, has a strorginfluence on the airplane stoppingdistance. These studies have also shown that satisfactorystopping distance is achieved when the reversers are operatedcontinuously at full rated takeoff power down to a rollingspeed of at least 20 knots. In contrast, most commercialairplanes today must cut off the reverser or modulate the

t engine power setting below 60 knots. The cutoff velocityis determined primarily by engine tolerance to reverser ex-haust reingestion and foreign object ingestion (dust and rocksfrom an unimproved field).

To avoid the problems of reingestion and foreign objectc damage at low ground roll speed, the thrust.reverser must be-

designed to control the direction of the reverser exhaus""away from the engine inlet, ground surfaces, and adjacent aircraftsurfaces.There are few regions in which the exhaust flow can bedirectec,

1) Upward and forward above the nacelle forward of the wingleading edge (Figure 14a) - - - This requires asymmetric exhaustflow with the corresponding problems of internal pressure losses,unsymmetrical structural loads and for a fan thrust reverserpotential pressure distortion at the fan exit. An advantageto this type of flow control, however, is the additional gearloading obtained from the vertical thrust component of theexhaust flow which increases the braking forces.

2) Outboard side of outboard nacelle (Figure 14b) - - - Impringe-ment on the ground outboard of the outboard nacelle may beallowable. For a two engine STOL aircraft this could be a

35

a) FLOW CONTROL UPWARD b) FLOW CONTROL UPWARD ANDOUTBOARD (OUTBOARD NACELLEONLY)

c0 UPWARD AFT OR WING d) AFT OF WING TRAILING EDGELEADING EDGE

FigureM1: POSSIBLE REVERSER EXHAUST FLOW REGIONS TO MINIMI/E REINGESTION

36

satisfactory approach. However, left and right hand reverserdesigns would be required for either two or four engine air-craft.

3) All flow above the wing aft of leading edge (Figure 14c)- - - This requires apertures in-the wing to direct the reverserflow upward and forward.

4) All flow aft of the wing trailing edge (Figure 14d) - - -This installation is ideally suited for a target thrust reverser.However, it will require removal of wing trailing edge flapsections to accommodate the extended nacelle.

The thrust reverser concepts were configured to meet the aboveflow directional control requirements.

2.1.4.2 Primary Thrust Reversing and Spoiling Options

Unmixed Flow EnginesIt is well known that as the bypass ratio of a turbofanengine increases and the corresponding primary thrust de-

C creases, the benefits derived from reversing the primarythrust diminish (Reference 5). This is shown in Figure 15.The curves were derived from engine data for the Pratt &Whitney Aircraft STF 342B (BPR 6.0), STF 342D (BPR 3.0) andSTF 344 (BPR 12.0) unmixed flow engines (References 2 and 3).

SBased on these results, the following guidelines were estab-lished for thrust reverser concepts for unmixed flow engines:

1. Bypass ratio 3.0 unmixed flow engineb require thrustreverser systems for both the fan and )rimary flows.

2. A mechanical spoiler may be used to spoil the primarythrust of bypass ratio 6.0 unmixed flow engines.

3. A mechanical spoiler is recommended to spoil theprimary of bypass ratio 12.0 engine. The spoilermay be eliminated provided fan reverser efficiencyof at least 50 percent can be achieved.

"Cycle Spoiling" of Primary Thrust for Mixed Flow EnginesThrust reverser systems for mixed flow engines present specialdesign prblems especially for high bypass ratio turbofanengines with the flow directional control requirements fora STOL transport. The major difficulty encountered is concernedwith the design requirements of the blocker door mechanism.Because the exhaust duct for such engines is relatively large,the mechanism to block and turn the mixed exhaust flow becomesle~rge and, therefore, is heavy. Also, the nacelle lengthmust be extended to accommodate the reverser system for amixed flow engine as shown in Figure 16a.

37

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STF 342D STF 3428. STF 344

Figure 15: EFFECT OF PRIMARY REVERSE THRUST MODE ON REVERSEREFFECTIVENESS (17 R) AI 0

38

Cascade Reverser

Blocker Door

C

Figure I&A: MIXED FLOW THRUST REVERSER

Cascade ReverserFen Duct Only

CBlocker Door

Primary Exhaust

C Figure 1&-8: MIXED FLOW WITH FAN THRUST REVERSER AND CYCLESPOILING OF PRIMARY THRUST

39

One method to reduce the nacelle length and weight involvesreversing only the fan exhaust flow and allowing the pri-mary flow to exhaust from the nozzle. This method is called"cycle spoiling" and is illustrated in Figure 16b. The effect 0of this operation is to cause the primary flow to be "overarea which spoils the primary thrust. A study of "cyclespoiling" was made by Pratt & Whitney Aircraft to assess theeffects on engine performance and also to identify engineproblem areas during reverse mode.

As a typical commercial mixed flow turbofan engine, the STF 402is a fan-low-high, 24006F T.I.T., BPR 5.0, 1.57 FPR mixedflow engine utilizing an advanced high spool core. Figure 17shows STF 402 "cycle spoiling" operation in the reversemode (separate streams) for various primary stream jet areas,and two values of fan duct exhaust area. A value of AjE/AjE -

1.4 is the size of the primary splitter area. It is believedthat for most installations the primary flow will be controlledby the area of the primary splitter, A splitter, and the re-mainder of the nozzle will fill up witR ambient air. However,this will depend on the duct length between the splitter and (Jthe nozzle exit. If the duct is sufficiently long the con-trolling area could occur at the nozzle exit. Note that forA /A * - 1.10 and AJD/A * - 1.0, the separate stream engineJEJE _D Dcycle and performance co ncides with the mixed flow engine.The engine must be throttled as primary area is increasedto avoid low rotor overspeed. Note that the total thrust isdropping off as fan thrust remains about constant, indicatingthe primary thrust is being spoiled.

During the reverse operation the fan, low and high compressormay need more surge margin than during sea level takeoffsteady state operation as inlet distortion is allowed to in-crease. Thus, the loss in low compressor surge margin shownin Figures 17 may be intolerable and would have to be recti-fied, probably with interstage bleed. There is no loss in fanor high compressor surge margin for the case where fan ductarea is held constant. When the fan area is increased, thefan gains considerable surge margin.

The results shown in Figure 18 indicate that low rotor over-speed capability may be desirable. A comparison of the effecton performance during reverse if fan overspeed were designedfor, and if fan overspeed is ncý allowed. This overspeedcapability would have to be designed into the engine orreverse thrust would have to be applied at a reduced powersetting such that SLTO N1 would not be exceeded. If theoverspeed capability were included it would be accompanied bya weight increase. Figure 19 shows the STF 402 sea levelstatic low rotor speed characteristics at part throttle.

40

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42

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43

Reverser effectiveness as a functioi. of primary stream ex-haust area is shown in Figure 20. If the primary flow matchesto the primary splitter area, the reverser effectiveness is23.8 percent and 24.1 percent for throttled and overspeedreverse modes, respectively, assuming the efficiency of thefan reverser is 50 percent. This reverser effectivenessis not sufficient to meet the landing field length for aSTOL transport. Therefore, it appears that "cycle spoiling"would not be suitable for a BPR 5.0 engine.

Potential reverser effe'itiveness available using "cyclespoiling" for a BPR 6.0 engine was studied using a Boeingparametric engine computer program (References 5). 2kr unmixedflow engine was used where the primary area was varic overa range of 0.85 to 1.70 of the equivalent primary flow areaof a mixed flow engine. The results of the study are shownin Figures 21 and 22. As showni in Figure 22 reverser effect-iveness of 32 percent could be expected for a bypass ratio6.0 engine assuming the basic efficiency of the fan reverseris 50 percent. The operating point shown was determined fora mixed flow simulation of the STF 342B engine for which thearea of the primary flow at the mixer was 4.163 ft 2 . Thisarea was assumed to be the controlling area o. the primarystream during fan thrust reversing.

2.1.4.3 :,anding Roll Analysis

A landinS field study was conducted to assess the influence ofreverer efficiency, cutoff speed, actuation delay time, andrunway condition on landing roll distance. In addition, theeffect of having a vertical thrust component during thrustreversing, and the affect of airplane gross weight on thelanding roll distance was investigated. An existing Boeingcomputer program, TEM-036D (REference 6) wan used for thispurpose.

The analysis was based on the Model 953-758 baseline config-uration and the STF 342B bypass ratio 6.0 engine performznca.

Figures 23, 24 and 25 show the landing roll distance as afunction of reverser efficiencyn•_ cutoff velocity, and delaytime for icy field ( p- .10), and wet field ( p- .30) and dryfield (0 - .40) conditions respectively. The important para-meters that effect the landing roll distance are the delaytime and the reverser cutoff velocity. Significant gains inlanding roll distance occur when the reverser cutoff speedis reduced from 40 to 20 knots. Below 20 knots, the gains inlanding roll distance have less significance. Also, thereare significant improvements obtained when the delay time isreduced tu instantaneous actuation at touchdown. Each secondof delay means approximately 103 feet of runway length. required

44

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45

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46

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47

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£ Based on these results, an optimum reverser system for STOLapplications would have zero delay time, less than 20 knotscutoff speed, and an efficiency greater than 30 percent. Itshould be noted that this study assumes the fan and primarythrust is reversed. However, the results can be applied tospoiled primary thrust and fan thrust reverser systems by inter-

C changing the reverser effectiveness for the system and reverserefficiency in the Figures.

As discussed in Section 2.1.4.1' flow directional controlrequirements for some reverser system will result in verticalforce compornts during thrust reversal. The vertical componentwill place additional loads on the landing gear and will increasethe braking forces. The effect of the vertical force componenton landing roll distance is shown in Figure 26. Approximately5 percent improvement in landing roll distance can be obtainedwith icy runway conditions and up to 10 percent improvementscan be obtained under wet or dry field conditions.

The effect of airplane gross weight on landing roll distanceis shown in Figures 27 for various runway conditions. Thesecurves show that gross weight has a significant effect onlanding roll distance.

C 2.1.4.4 Thrust Reverser Concepts for EBF Lift Systems

A total of four thrust reverser concepts were consideredfor an EBF system, each utilizing cascade thrust reversersfor flow control. The concepts are shown in Figures 28through 31.

An unmixed flow engine installation is shown in Figure 28.Thrust reversing is accomplished using a fan cascade thrustreverser and a mechanical primary thrust spoiler. Theprimary spoiler mechanism shown is similar to the spoilerused on the General Electric CF6-6 engine. It must benoted that other types of spoiler systems can be configuredfor the unmixed flow engine including target and blocker/deflector systems. A disadvantage of the primary thrustspoiler concept for high wing, four engine aircraft install-ation is that the primary flow would be directed to theside of the nacel.e, which could result in impingement ofthe exhaust flow on tha airplane fuselage and adjacentnacelles. This could result in higher reverser cutoff speeddue to possible surface heating and reingestion problems.

A concept for a mixed flow engine installation is shown inFigure 29. This concept also uses a fan cascade thrustreverser to obtain the required flow directional control."Cycle spoiling" is used to spoil the thrust of the primaryflow.

55

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56

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The thrust reverser concept shown in Figures 28 and 29utilize a translating cowl and blocker door mechanismsimilar to the mechanism used on thaBoeing 747/JT9D primaryflow thrust reverser (Reference 7). The cascades arefixed in the upper 180* sector of the nacelle and thecascade strongbacks are skewed to provide the requiredflow control upward. Air driven ball-screw actuators areused to translate the fan cowl aft exposing the cascadevanes. As the cowl translates, a drag link mechanismdeploys the blocker doors. The reverser cascades areconstructed of cast alumninum vanes and the blocker doorsare constructed of aluminum honeycomb panels.

The difficulties of designing a thrust reverser systemfor mixed flow turbofan engines that reverse the total fanand primary flows are demonstrated by the concepts shown inFigures 30 and 31. Concept-14, shown in Figure 30 uses aconventional clamshell blocker door mechanism similar to thetype used on the Boeing 727/JT8D and Boeing 707/JT3D thrustreverser systems. Two clamshell blocker doors with a centralpivot block the engine and fan exhaust flow and divert theflow through the upper portion of the nacelle. Fixed cascadesare exposed when the clamshell is deployed. This techniqueis not compatible with the •.everser exhaust flow controlrequirement because the cas.cade aperture is too long and theclamshell cannot seal the entire cascade during cruise mode.Also, during reverse mode the clamshell blocks a portion ofthe available cascade flow area. An alternate design fora mixed flow engine is shown in Figure 31. A translatingsleeve and fixed plug block the mixed flow and primary flowsduring thrust reversing. Fixed cascades provide the requiredflow directional control. Air driven ball-screw actuatorsare used to translate the cowl sleeve. The thrust reversercascade vanes, inner surface of the translating sleeve andfixed plug are constructed of steel. This concept eliminatesblocker doors and linkages and also eliminates the problemsencountered with the clamshell mechanism.

2.1.4.5 Thrust Reverser and Thrust Vectoring Systems forMF+VT Lift Systems

Thrust reverser and thrust vectoring concepts for mechanicalflap and vectored thrust lift systems included single podconcepts for BPR 3.0, 6.0, and 12.0 engines, and dual podconcepts for BPR 3.0 engines. Eleven concepts were evaluated,Figures 32 through 44.

Mixed Flow Engines --- Single PodThe design options available to the designer are basicallyeither to combine the functions of the thrust vectoring andthrust reversing system into a sinqle mechanism or to separate

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the thrust reversing and vectoring function and provide acomplete design for each system. The combined TR/TV is per-haps the most desirable approach primarily because of the V

potential weight savings and reduced mechanical systemsrequired. For example, a single actuation system and controlmay be utilized for a combined TR/TV system where two actu-ation and control systems are required for separate TR andTV installations. However, it is probable -hat the combinedTR/TV system will require more mechanical complexity toinclude both functions.

Separate thrust reverser and thrust vectoring systems thatrequire a common exhaust duct will require additional nacellelength, and will result in a high weight installation. Analternate to separate thrust reverser and vectoring system isthe "cycle spoiling" thrust reveiser technique. "Cycle spoiling"allows satisfactory flow directional control to be achieved witha shorter overall nacelle and less weight. This technique wasutilized on several of the concepts to obtain the lightestweight system possible.

A combined thrust reverser and vectoring concept for a BPR 3.0mixed flow engine is shown in Figure 32. Cascades apertures inthe upper half of the nacelle direct the flow upward and forwardfor thrust reversing. Cascades on the bottom of the nacelledirect the flow down and aft for thrust vectoring. Continuousthrust vector angle modulation between 45 and 90 degreees isprovided by variable angle cascades. Area match is maintainedby a mechanism that opens additional blade rows in the 45degree positon. The TR or TV mode is selected by an annularrotating valve. A translating sleeve covers the TR and TVapertures during the cruise mode and also blocks the flowby contacting the fixed position plug during the TR and TVmode. A detailed design of the concept is shown in Figure 33.The thruaz reverser and thrust vectoring cascade vanes andthe rotating selector valve are corlstructed of steel. Airdriven ball-screw actuators are u;ed to translate the sleevefore and aft. An electric motor and linkage is used to actuatethe rotating selector valve.

Another combined thrust reverser and vectoring system concept isshown in Figure 34. The system consists of three deflectordoors (inner, middle, and outer) mounted aft of tne exhaustnozzle and utilizing common hinge points. The inner and outerdoors are geared together through a hub mounted planetary geartrain (3:1 ratio). The middle aad outer doors are linked to-gether through a dwell mechanism to allow the middle door torotate 750 before the outer door moves. A detailed schematicof the mechanism and defl rtor door position is shown in Figure35. The middle door is 'riven by two ball screw jacks and the first750 rotation produces 0 through 750 vectored thrust. The next

68

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69

pr500 rotation of the middle door moves the outer door 600 andthe inner door rotates 1800 (through the 3:1 gear ratio, innerto outer door). This puts the three doors into reverse thrustposition. The deflector doors are constructed of steel honey-comb sandwich panels. A variable geometry nozzle will be re-quired to reduce the Mach number of the flow entering the de-flector during thrust vectoring. Engine flow control must bemaintained at the deflector exit in order to avoid the lossesassociated with high Mach number turning.

Figure 36 shows a concept that separates the thrust vectoringand thrust reverser functions. A three bearing nozzle isutilized for thrust vector modulation from horizontal to amaximum of 900 depending on the bearing plane angle. The useof multiple counter rotating duct segments eliminates sideforces during vectoring. An electric or hydraulic drive systemwith gears on each segment are used to rotate the segments.Steel honeycomb sandwich panels are used to fabricate theduct segments.

Thethrust reverser system consists of a fan cascade thrustreverser and "cycle-spoiling" of primary thrust. The reverserconcept shown consists of internal and external doors withfixed cascades in the upper 1800 sector of the nacelle. Hydrau-lic or pneumatic actuators deploy the doors. The cascades,and internal and external doors are made of aluminum.

A multibearing nozzle may also be used as a combined thrustreverser and vectoring system as shown in Figuze 37. Witha bearing angle of 600, the nozzle may be deflected to amaximum of 1200, During approach and landing the nozzledeflection angle would be at approximately 750. At touch-down the nozzle would simultaneously move to the maximumdeflection position and rotate 900 to direct the exhaustflow outboard. Because of the possibility of cross flowingestion by an adjacent nacelle inlet, this concept willprobably be applicable to aircraft with one engine undereach wing.

The concept shown in Figure 38 employs a lobstertail-typeexternal deflector vectoring system consisting of threehemispherical panels deployed aft of the nacelle. The de-flector doors have a common hinge and are deployed usingan air driven ball-screw actuator with incremental positioncapability to obtain the desired vectored thrust angle. Engineflow control must be maintained at the deflector exit utiliz-ing a variable geometry nozzle to avoid the losses associatedwith high Mach number turning. The thrust reverser systemconsists of a fan cascade thrust reverser and "cycle-spoiling"of the primary thrust. It is the same system discussed pre-viously for the multibearing vectoring nozzle concept.

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Figure 39 shows a vectoring concept consisting of a rect-angular nozzle with fixed vertical side walls and hingedhorizontal panels. During thrust vectoring, the horizontalpanel at the bottom of the nacelle is translated forwardusing an electric or hydraulic motor and a rack and piniondrive mechanism. The upper hinged panels are slaved to themotion of the bottom panel using linkages not shown in theschematic. The thrust vectoring nozzle and side walls areconstructed of steel honeycomb sandwich panels. The degreeof mechanical complexity of this devise is equivalent toother vectoring concepts. The primary design problems areconcerned with sealing the side walls to prevent leakage andmaintaining a good aerodynamic shape to minimize nacelle drag.The thrust reverser system concsists of a fan cascade thrustreverser system and "cycle-spoiling" of the primary thrust.

Unimixed Flow Engines - Single PodThe rotating nozzle concept shown in Figure 40 is believed tobe the simplest system to provide thrust vectoring and thrustreversing of unmixed engine exhaust flow:s. The vectoringnozzles are rotatable from +900 for vectored thrust to -1350for reversed thrust. The nozzles would probably be rotatedforward during reverser deployment without serioais risk ofreingestion. Satisfactory reverse thrust can be obtained atthe -1350 rotation angle position. The rotation rates duringreverse mode deployment must be high, approximately 180°/secondwhich is twice the rate of the current Pegasus nozzles used onthe Harrier V/STOL Fighter aircraft. A hydraulic motor connect-ed to a gearbox and chain drive mechanism is used to rotatethe nozzles. The fan nozzles are made of aluminum and theprimary nozzles are made of steel.

There are few vectoring system concepts that are applicableto bypass ratio 12.0 unmixed flow engines. The single bearingnozzle concept discussed above is limited to engines with bypassratios of approximately 6.0 or less. When scaled to largerbypass ratios en~ine size (i.e. BPR 12.0), the fbw area re-quired for the fan nozzle increases the frontal area of the nacellewhich would substantially increase nacelle drag. Two conceptsfor BPR 12.0 unmixed flow engines are shown in Figures 41 and42. The multibearing vectoring concept (Figure 4] best ill-ustrates the many difficulties of designing a satisfactory thrustvectoring arrangement for BPR 12.0 engines. The large sizerequired for the fan duct results in a long nacelle that doesnot have good aerodynamic contours. Also, the weight of theducts and vectoring nozzle is prohibitive. The external de-flector concept shown in Figure 42 utilizes a lobstertail de-flector to achieve thrust vectoring. The deflector is ceployedusing air driven ball screw actuators with incremental adjust-ment capability. The primary problem with this concept is theability to maintain air flow match of the primar" stream during

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It should be noted that it is possible to vector only thefan flow of a BPR 12.0 engine and obtain satisfactory vector-ing performance. Since the fan thrust is much greater thanthe primary thrust there may be a favorable trade betweenthe savings in system weight and ccmplexity and the loss inavailable vectored thrust. As shown in Figure 43, to achievean effective vector angle of 750, the fan thrust will requirea mechanical deflection angle of 820 and wil produce a vector-ed thrust ratio of FRESULTANT- / FGROSS = .92.

VECTORED

Mixed Flow Engines --- Dual PodsThe design study included dual pod engine installationsusing BPR 3.0 mixed flow engines. BPR 3.0 mixed flow enginesnecessitate vectoring and reversing all of the engine flow (asdiscussed in Section 2.1.4.2) to achieve satisfactory perform-Sance. Therefore, the available design options are separatethrust vectoring and reversing systems or a combined thrustvectoring/reversing system. Because of the potential weightadvantage, a combined thrust reverser and vectoring systemis probably the best option for a BPR 3.0 wiixed flow engine.

Of the two combined TR/TV concepts considered for the singlepod mixed flow engine installation, the external deflector/target thrust reverser/vectoring system shown in Figure 34was selected for the dual pod installation. A schematic isshown in Figure 44. Thisinstallation is relatively simple,lightweight, and provides good thrust vectoring and thrustreversing performance.

2.1.4.6 Thrust Reverser Concepts for USB Lift Systems

Two thrust reverser concepts are shown iii Zigure 45 and 46for an overwing USB installation. The BPR 6.0 unmixed flowinstallation, Figure 45, utilizes a fan cascade thrust re-A verser and a mechanical primary thrust spoiler. The fixed

-} cascades direct the flow upward above the wing surface. TheBPR 6.0 mixed flow engine concept, Figure 46, utilizes atarget thrust reverser consisting of two hinged doors, actu-ated by one centrally located hydraulic actuator. The target

79

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deflector door is hinged to the nacelle structure. The de-flector door is hinged to the main deflector door. As thetarget deflector is deployed the lip door is slaved intoposition using mechanical linkages. The deflector doors areconstructed of stainless steel. A mtore detailed schematic ofthe reverser installation is shown in Figure 47.

In order to obtain effective vectoring performance for uppersurface blowing, the engine exhaust flow must be attached tothe wing upper surface. This necessitates exhaust nozzledesigns that are D-shaped (aspect ratio of approximately 3.0)and a highly integrated wing ai,d nacelle design. Boeingstudies of such nacelle configurations show that the mixedflow engine concept shown in Figure 46 and 47 offers goodreverser performance, minimum weight, and good mechanicaldesign relative to other nacelle concepts. The unmixed flowconcept shown in Figure 45 would not be an acceptable install-ation for upper surface blowing because of the requirementscited above.

2.1.5 Fan Cascade Thrust Reverser Detailed Design

The objective of the detailed design study was to demonstratethe feasibility of the fan cascade thrust reverser concept usedfor the EBF and MF+VT engine installation. The problems ofexhaust flow control, mechanization, and actuation were

I examined in more detail.

Current high bypass flow engines reverse the fan air throughopenings provided in portions of their full 360° circumference.This allows them to use relatively short cascade assemblies andsingle hinged, one p4 ece, blocker doors. To avoid the re-ingestion and ground impingement problems of current cascadedesigns, the reverser exhaust must be directed through open-ings in the upper 1800 segment of the nacelle. This necessit-ates the installation of cascade panels approximately twiceas long as those in current use. The bicker door mechanismand proper sealing of the cascade openings becomes a majordesign problem. The use of bi-fold panels or a similardesign, is required to block the fan flow during reverseroperation and also provide coverage of the cascades duringcruise.

Analysis of the fan cascade thrust reverser concepts discussedin Section 2.1.4 disclosed several deficiencies. First, thetranslating sleeve concept, Figure 28, would require highactuation loads because of the large segment of cowl structurein motion and the fast deployment time required. This wouldrequire large size actuators and corresponding structure tocarry the loads which would result in higher weight. Also, itwas recognized that the blocker door mechanism envisionedwas not feasible because of the long cascade length and theresulting sealing problems during the cruise mode. The re-verser concept shown in kigure 36 is not feasible because the

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external doors would ekperience .high loads during deployment.The resulting eight penialties for the actuation system andstructu're wouildno be acceptable. Therefore, a reverser designwas conceived that e himinated the deficiencies of the otherconcepts.

The revised fan cascade thrust reverser concept is shown inFigure 40. The design utilizes cascade panels and deflectordoors located in the upper 1800 segment of the nacelle. The

0 cascades have an airfoil cross section with a leaving angleof approximately 500 at the blade throat. The cascadessolidity, c/l, was selected as 1.40 based on Model 747 thrustreverser development tests. The blocker doors form a smoothsurface for the fan duct in the cruise position and with anactuator stroke of 4", the cascades are fully exposed as thedoors block the fan exhaust for thrust reversing. The Pir-flow area match during reverser deployment is shown inFigure 49. The outer doors are oriented in P stream-wisedirection for possible in-flight.deployment. Their openingangle is intended to prevent possible cross-reingestion onadjacent engines during reverser operation. Interconnectinglinkages are used-to operate the outer doors with a singlehydraulic actuator for each side of the nacelle.

Various blocker door design concepts were examined in tryingto develop a satisfactory thrust reverser design. Two of theconcepts are shown in Figures 50 and 51. The design in Figure50 utilized a bi-fold door arrangement mounted to a track.Although the design provides excellent internal geometry forthe reverser exhaust, the airflow area match during reverserdeployment is poor. When the blocker door is at approximatelyone-half of its full cycle, the fan -duct is totally blockedand only 50 percent of the cascade area is exposed. Theconcept shown in Figure 51 corrected the area match problem;however, it has an open area between the blocker doors andthe track while in the cruise mode. The open area could notbe easily sealed without added mechanism and, therefore, addedcomplexity to the reverser syatem. The concept shown in

C Figure 48 corrects the airflow match and sealing problemsencountered with the previous designs.

Various locations for the blocker door actuator were studiedbefore selecting the placement shown in Section A-A of Figure48. Early studies placed the cctuator at the forward end ofthe blocker door between the outer fan duct w•ll and the out-side of the nacelle. This location required a separate linkbetween the door and actuator, approximately 10" long, "-hichwould follow the blocker door into the blocked positioit andbe exposed to the reverser gases along with a portion of theactuator ram. The required stroke of this actuator would be18" and its body length would be approximately 26" long. This

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length would place the actuator attach point at the forwardflange of the engine fan cake. This location is consideredunacceptable because of the various engine accessories andservice lines on the fan case. To alleviate this problemand still actuate the door from this location, the entireengine nacelle would have-to be lengthened approximately 18"with the cascades moved aft by this same amount. The actuatorand its connecting linkage could then be positioned aft ofthe fan case rear flange. Also, the engine strut would haveto be lengthened in.order to keep the reverser gases forwardof the wing leading edge. This potential increase in weightof the strut and nacelle resulted in the decision to place theactuator as shown in Figure 48. The temperature in this loca-tion would be an estimated 300° - 400°F. The desirability tokeep hydraulic fluid away from the engine would indicate thatan air operated actuator be used rather than a hydraulic device.

However, if shrouded lines were discretely employed, hydraulicfluia should not become a decisive safety factor and eithera hydraulic or pneumatic actuator could be used.

2.2 Task 2.2 --- Analyze Performance of TR/TV Systems

The design study conducted during Task 2.1 included thrustreverser (TR) and thrust vectoring (TV) systems applicableto three high lift systems for STOL tactical transportsincluding:

1. externally blown flaps2. mechanical flap and vectored thrust3. upper surface blowin

The TR/TV concepts were evalupt.-d c the basis of TR and TVperformance and weight with the objective of obtaining thebest TR/TV performance for the lightest weight system. Also,the impact of the TR/TV concept on the airplane aerodynamiccharacteristics was included in the evaluation. The purposeof the evaluation was to determine the most promising con-figurations for model tests during Part 1C.

Internal performance for the cruise nozzles, vectoring nozzles,vectoring nozzles: and thrust reversers was computed usingthe empirical prediction methods developed during Part lA,Task 1.1 of the program. Detailed descriptions of the methodsare provided in Volume I of this report. Weight estimateswere made using Class I estimating methods, considering thesize, materials, and actuation systems of the nacelle andTR/TV system installation. The weight accuracy is estimatedto be ± 10 percent. This does not include weight that wouldbe needed for a "quiet" nacelle, or flutter. The range ofweights for the nacelle configurations is shown in Figure 52.

94

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95

2.2.1 Externally Blown Flap Lift Systems

The thrust reverser concepts evaluated for an EBF propulsionsystem installation are shown in Figures 28 through 31. TableVII compares the predicted performance and weight for eachconcept. As shown in the Table, concept -16, (Figure 31) hasthe highest reverser performance, but the total propulsioninstallation is 500 lb/installation heavier than the otherfeasible concepts. Concepts -02 and -03 (Figures 28 and 29respectively) have essentially the same installed weight,but concept -02, a fan cascade and mechanical primary spoiler,has better reverser performance. Concept -03 utilizes a fancascade and "cycle spoiling" of the primary thrust duringthrust reversing.

These thrust reverser concepts will cause no adverse effecton engine operation due to the mechanical design of the re-verser. The detailed design study, Section 2.1.5, showed thatthe blocker door mechanism can be designed to maintain airflowmatch can be maintained for the translating sleeve and cascadeTR system (concept -16). However, exhausting the reverserflow from the upper 180* sector of the nacelle could distortthe internal flow which could affect engine operation. Thisis especially true for the fan cascade thrust reverser concepts(-02 and -03). The degree of this problem is dependent on theproximity of the reverser to the fan exit.

On the basis of Table VII, concept -02 has the best overallsystem performance and weight. The reverser performance isacceptable to achieve STOL landing field length, and it hasessentially the same weight as the lowest weight concept (1570vs. 1550 lb). One disadvantage of the concept is that the ex-haust flow from the mechanical primary thrust spoiler would bedirected to each side of the nacelle, resulting in impingementof the exhaust flow on the airplane fuselage (inboard nacelle)and on the adjacent nacelle. This could result in higher re-verser cutoff speeds due to possible surface heating and re-ingestion problems.

2.2.2 Mechanical Flap and Vectored Thrust Lift Systems

The evaluation of MF+VT vectoring concepts emphasized thethrust vectoring performance and propulsion system weight.Thrust reverser performance was considered for those systemswith equivalent thrust vectoring performance and weight. TableVIII compares the predicted performance and weight for eachconcept.

Mixed Flow Engines --- Single PodAs shown in Table VIII, concepts -06, -07, -13, and -19 (Figures36, 38, 37, and 34) have essentially the same weight (within100 lb) and vectoring performance. Concepts -13 and -19 have

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the highest thrust reverser performance which makes theseconcepts attractive for a mixed flow engine installation.However, the under area air flow match characteristic ofconcept -13 suggests that a variable area nozzle will berequired for that concept to maintain air flow match duringreverse mode. This will result in a weight increase. Asnoted in Section 2.1.4, applications of concept -13 will pro-bably ;e limited to aircraft with, one engine under each wingbecause of the possibility of cross-ingestion and groundimpingment during reverse mode. Concept -06 has potentiallygreater reverse thrust than concept-07 because of the lengthof the multibearing nozzle duct. It is possible that the longerduct length would cause higher spoiling of the primary flow.

Since concepts -06 and -19 require cruise nozzle area variationduring the vectoring mode (and concept -19 reverse mode) engineareacontrol will be an important consideration during thesteady state and transient conditions. It is believed thatS~engine airflow match will be possible but will require a reliablecontrol system that senses engine power demand, nozzle area

and deflector position.

Therefore, it appears that the best overall vectoring systemconcept of those studied for mixed flow engines on four-engineaircraft could be either the multibearing concept (concept -C6Figure 36) or the combined thrust vectoring/reverser externaldeflector concept (concept -19, Figure 34). Concept -13would be best suited for airplane configurations with oneengine under each wing. Although these concepts were drawn fora BPR 6.0 engine, only concepts -19 and -13 would be suitablefor BPR 3.0. The "cycle spoiling" feature of concept -06wwould be unsuitable for engines with BPR < 6.0.

Uni'':ed Flow Engines --- Single PodTTMiotating nozzle concept (Figure 40) offers a techniqueto x,,ctor and reverse the thrust of bypass ratio 6.0 or lessunmixed flow engines. This concept was the only zystemevaluated for BPR 3.0 and 6.0 engines. Vectoring performanceis high because the nozzle geometry is virtually the sameas the cruise and vectored positions and additional pressurelosses during vectoring or reversing would be minimal. Itshould be noted, however, that cruise nozzle performance willbe affected by the bifurcated fan and primary ducts.

As shown in Tabel VIII the concepts evaluated for BPR 12.0unmixed flow engines have poor weight characteristics. Itwas concluded from the evaluation that thrust vectoring systemsfor BPR 12.0 size engines are probably not feasible primarilydue to excessive weight.

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Mixed Flow --- Dual PodsAs shown in Table VIII the external deflector/target thrustvectoring/reverser systems offer good performance and-weightcharacteristics for BPR 3.0 dual pod installations.

Aerodynamic Stability and Control ConsiderationsThe effective thrust vector of a mechanical flap and vectoredthrust lift system rarely acts through the airplane center ofgravity. Therefore, the resulting thrust pitching moment mustbe cnsidered when balancing a vectored thrust airplane. Accept-able engine locations must be defined to avoid adverse effectson the stability and control of the aircraft. Figure 53illustrates how four stability and control balancing require-ments are used to define the envelope of acceptable enginelocations. These criteria are for takeoff rotation, longi-tudinal control power, static tip up, and static longitudinalstability. Of the four boundaries the forward boundary ofthe envelope, static longitudinal stability is the most critical.Placing the thrust vector forward of the envelope means thatthe airplane will be unstable because of the horizontal tailsize cannot compensate for the adverse pitching moment.

As shown in Figure 53 concepts -06, -07, and -13 are withinthe acceptable thrust vector location envelope, and concepts-10 and -19 are outside the boundary. Therefore, rebalancingof the airplane configureation is required for concepti -10and -19. This could require either resizing the horizontaltail or relocating the wing further aft toward the c.g., orboth, with corresponding possible weight penalties. Rebalancingthe airplane to accommodate concept -10 will be more difficultthan for concept -19 because the pitching moment is greater.It should be noted that the pitching moment problem existsfor those systems that combine the function of the thrust re-verser and thrust vectoring systems and directs the reverserexhaust forward of the wing leading edge. Concepts thatseparate the thrust vectoring and thrust reverser systems donot have pitching moment problems.

2.2.3 Upper Surface Blowing Lift Systems

Evaluation of upper surface blowing concepts was based pri-marily on the reverser performance and weight comparisons. Itwas assumed that the thrust reverser concept would not influencethe performance of the vectoring system. Table IX comparesthe performance and weight characteristics for the two thrustreverser concepts for upper surface blowing lift systems. Con-cept -18 (Figures 46 and 47) provides the required exhaustflow characteristics for optimum USB performance, and alsooffers good reverser performance and weight characteristics.This concept has been successfully applied to STOL configurationscurrently under study at Boeing.

102

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2.2.4 Conclusions

The results of the TR/TV concept evaluations are summarizedin Table X. The following conclusions can be made based onthe evaluation results:

1. The thrust reverser system for externally blown flaplift systems will probably involve the use of a fan

0 cascade thrust reverser.

2. Mechanical flap and vectored thrust lift systems

could use either

a. rotating nozzles* Ib. multibearing vectoring nozzlesc. external deflector/target thrust vectoring/

reversing systems

depending on the type of engine cycle (mixed or un-mixed flow).

~ The rotating nozzle vectoring system would be used

for unmixed flow engines and would present airplanebalancing problems due to the thrust vector locationand the resulting adverse pitching moment. The ex-• i ternal deflector/target TR/TV system would also pose

balancing difficulties but to a lesser degree. Multi-bearing vectoring nozzle installations would presentno airplane balancing problems.

3. Upper surface blowing lift systems will utilize anexternal target thrust reverser system installed witha mixed flow engine.

2.3 Task 2.3 Select Designs for Part 1C

On the basis of the evaluations, the following TR/TV sys-tems representing various lift systems for STOL tactical trans-ports were considered for Part 1C static tests and future lowspeed wind tunnel tests:

1. A fan cascade thrust reverser system that exhauststhe fan flow through cascades installed in theupper 1800 sector of the nacelle (EBF, MF + VT).

2. An external deflector/target TR/TV system thatcombines the functions of thrust vectoring andreversing into a single mechanism. (MF + VT)

3. A multibearing vectoring nozzle (MF + VT).

4. An external target thrust reverser for an over-wing installation (USB).

105

Table X: EVALUATION SUMMARY

LIFT SYSTEM ENGINE TYPE DESCRIPTION TR/TV CONCEPT

EXTERNALLY BPR 6.0 FAN CASCADE THRUST TR/TV-PP)02BLOWN FLAP UNMIXED REVERSER AND PRIMARY

THRUST SPOILER

BPR 12.0 FAN CASCADE THRUST TR/TV-PP)02UNMIXED REVERSER SCALED TO 5PR

12.0 NO PRIMARYSPOILER

MECH FLAP BPR 6.0 ROTATING FAN AND TR/TV-PP-10AND VECTORED UNMIXED PRIMARY NOZZLESTHRUST

BPR 6.0 MULTIBEARING VECTORING TR/TV-PP-13MIXED NOZZLE TR/TV SYSTEM

(a 1200)

EXTERNAL DEFLECTOR/ TR/TV-PP-19TARGET TR/TV SYSTEM

MULTIBEARING VECTORING TR/TV-PP.03NOZZLE FAN CASCADE THRUSTREVERSER AND PRIMARY"CYCLE SPOILING"

BPR 3.0 ROTATING FAN AND PRIMARY TR/TV-PP-10UNMIXED NOZZLES SCALED TO BPR

3.0 SIZE

BPR 3.0 MULTIBEARING VECTORING TR/TV-PP.13MIXED NOZZLE TR/TV SYSTEM SCALED TO BPR

(a = 1200) 3.0 SIZE

EXTERNAL DEFLECTOR/ TR/TV-PP-19TARGET TR/TV SYSTEM SCALED TO BPR

____ ___ ____ ___ ____ ___ 3,0 SIZE•BPR 12.0 NO VECTORING SYSTEMUNMIXED FEASIBLE IN THIS BYPASS

RATIO ENGINE

BPR 3.0 EXTERNAL DEFLECTOR/ TR/TV-PP-15MIXED TARGET TR/TV SYSTEMDUAL POD

UPPER SURFACE BPR 6.0 EXTERNAL TARGET THRUST TR/TV-PP-18BLOWING MIXED REVERSER SYSTEM

BPR 3.0 EXTERNAL TARGET THRUST TR/TV-PP-18MIXED FLOW REVERSER SYSTEM SCALED TO BPRSINGLE OR 3.0 SIZEDUAL POD

106

Parametric test data are available that are applicable to themultibearing nozzle and the external target thrust reverserconcepts. Multibearing nozzle data was obtained during PartIA of the program (Reference 3). A wie range of geometryvariations were tested that is adequate to define the vector-ing and reversing performance of multibearing nozzles. Themultibearing nozzle test results are reviewed in Volume I ofthis report. Data for the external target thrust reverser forthe USB lift system was obtained from a Boeing sponsoredstatic test program (Reference 9). The results have beenmade available to the STOL Transport TR/TV Program and arereviewed in Section IV.

Because of the existence of data for the multibearing nozzleand external target thrust reverser concepts further testingof these concepts was considered unnecessary. Therefore, thefan cascade thrust reverser system and the external deflector/target TR/TV system concepts were selected for Part 1C statictesting.

2.4 Task 2.4 - Test Plan Preparation

Test plans were developed for Part IC static tests for thethrust reverser and thrust vectoring concepts selected duringTask 2.3. The purpose of the tests was to obtain parametricperformance data as a function of geometric variables andengine power setting. The test plans (Reference 10) provide

A definition and descriptions of the test objectives, method-ology, models, facility requirements, conditions, procedures,and data acquisition requirments. The test plans were sub-mitted to the Air Force Project Engineer for approval on31 March 1972 and were approved on 26 May 1972.

2.5 Task 2.5 - Fabricate Hardware for Part IC

Test model design and fabrication was initiated irmaediatelyfollowing approval of the Air Force Project Engineer toproceed. Model fabrication was initiated on 17 June andwas completed on 27 July 1972. Detailed descriptions of thetest model hardware are contained in Section IV.

107

SECTION III

IART IC - MODEL TESTING

3.1 Task 3.1 -Cunduct Static Performance Test

The objective of Task 3.1 was to obtain parametric performancedata for the promising thrust reverser and thrust vectoringconcepts developed during Part lB design studies. Staticperformance data as a function of fundamental geometric var-iables and engine power setting was required.

As discussed in Section III, a fan cascade thrust reversersystem and an external deflector target TR/TV system wereselected for static testing. The tests were conducted atthe Boeing Propulsion/Noise Laboratories during July andAugust 1972. The test results are summarized here-in. De-tailed results are contained in a test report (Reference 11)submitted to the Air Force Project Engineer in October 1972.

3.1.1 Fan Cascade Thrust Reverser Model Test

A proposed method to minimize thrust reverser exhaust gasreingestion and aerodynamic interference on STOL tacticalaircraft is to direct the exhaust flow upward and forwardof the wing leading edge. For a fan cascade reverser system,this means the aperture opening of the fan cascade will belimited to the upper 1800 sector of the nacelle. The cascadeaperture will be longer than conventional cascade designs(i.e., 747, DC-10) as a result of this requirement. Thereare several problems associated with this design, mostnotably the potenetial distortion of the fan duct internalflow during reverser operation vertical directional controlof the exhaust flow while providing acceptable reverse thrustperformance.

108

ObjectivesThe objectives of the static test was to:

1) Obtain performance data for a fan cascade thrustreverser designed to exhaust the fan flow fromthe upper 1800 sector of the engine nacelle.

2) Investigate the characteristics of the fan ductinternal flow during reverser operation.

3) Establish design criteria for future wind tunnelmodels and for full scale hardware design.

Test Model

The test model simulated a fan cascade thrust reverser5 1suitable for either un-mixed flow or mixed flow (with

cycle spoiling of primary thrust) high bypass ratio turbofanengines. A schematic of the model is shown in Figure 54.The model consisted of an annular flow duct simulating afan exhaust duct, with simulated duct bifurcations for thestrut (upper) and engine accessory controls (lower), anda cascade reverser located in the upper portion of thenacille. The annular flow passage was held concentricby three struts located radially 1200 apart. Blockerinserts were used to simulate the thrust reverser blockerdoor geometry. Inserts for 450, 900, and 1350 weretested. A photograph of the model is shown in Figure 55.Each configuration was tested over the total pressure toambient pressure range of 1.2 to 2.2.

The cascade reverser used was a model fabricated for Model 747thrust reverser development testing. The cascade segmentswere rearranged to provide the desired flow directionalcontrol as shown in Figure 56. The cascade vane entranceangle varied depending on the axial location of the vaneand the leaving angle of each vane was fixed at 50".

Details of the model total pressure instrumentation are shownin Figure 54. Three rakes with a total of 33 probes wereinstalled radially 1200 apart. The probes are "area-weighted"so that each probe measures the total pressure in an equal-area sector of the flow. The model total pressure was computedusing the average of the duct total pressures. Model totaltemperature was measured by a chromel alumel thermocouplelocated in the plane of the total pressure probes.

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112

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Static pressure taps were installed in the inner and outer wallof the duct as illustrated in Figures 54 and 57 The firststatic tap in rows 2 and 7 were positioned in the same planeas the total pressure probes. In addition, two staticpressure taps were located adjacent to each total pressurerake, one on the inner wall and the other on the outer wall.These static taps were used to evaluate the characteristicsof the internal flow during reverser operation.

A total pressure survey of the fan cascade thrust reverserexhaust flow field was conducted using a 12 probe totalpressure rake installed at various radial positions as shownin Figure 58 and illustrated in Figure 59 The exit probeswere positioned approximately equidistant between each vaneexcept for the first vane where space was sufficient for twoprobes. Surveys were made for the radial positions andblocker door geometries shown in Figure 59 The rake wasalways oriented to be parallel to the cascade strongbacks(see Figure 59). The correct angle was verified using aninclinometer.

Test Results

Results of the fan cascade thrust reverser static test aresummarized below. Because some of the configurations hadnearly equivalent performance, data points are not shown inthe performance comparison plots to maintain clarity. Per-formance data for each configuration is presented in Reference11.

1. Reverser efficiency of at least 50% is possible for afan cascade thrust reverser that exhausts all of thefan flow through the upper portion of the nacelle,(Figure 60).

2. The highest reverser performance was obtained whenthe duct blocker door angle was 1350 (Figure 60and 61).

3. The cascade discharge coefficient was not appreciablyaffected by the duct blocker door geometry. Air flowmatch data indicate the reverser was slightly over-sized relative to the assumed cruise nozzle flow area(Figure 62).

4. The position of the cascade in the upper 1800 segment ofthe model resulted in internal flow distortion in theannular fan exhaust duct (Figure 63) . Static pressuredata show that the distortion diminished at approxi-mately x/h = -3.00 upstream of the cascade.

113

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9 (2

ROW AXIAL STATION X

1 270 .. 46 -1.30 -.50670 -. 30 .2.46 -1.20 -.50

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S2 is& .30

83 3000 4M384 WO 4.3035 1800 4m3

a 3000 4.30 _

Figure 57: Internal Duct Static Pressure Tap Locations

114

Ficure 58: FAN CASCADE REVERSER MODEL -EXIT TOTALPRESSURE RAKE INSTALLA TION

115

RADIAL 1STATIONS .V ~UPPER BII'URCATION

F CASCADESTRONG BACK

L9

.0 RADIAL STA.450 1,5,9

900 1,3.5,7,9

S1350I 1., 59 LOWER BIfURCATION

NOT TO SCALEEXIT TOTALPRESSURE RAKE

BETWEEN PROBEAND CASCADE

BLOCKER DOOR0 = 450, 900, 1350

Figure 59: FAN CASCADE THRUST REVERSER EXIT

TOTAL PRESSURE RAKE INSTALLATION

116

LA21,6 2 _ _ __ __-

I .48

I .

10 .40 4woi

- .34 135°

•. /

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.50

4.6o

//II

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1.0 12 1.4 1.6 1.8 2.0 2.2

S!o PRESSURE RATIO " PTAVE/P-o

• Figure 60: FAN CASCADE THRUST REVERSERREVERSER EFFICIENCY

CORRECTED REVERSER EFFICIENCY

117

w w• • • . • • • • •

IL.

cc- >

.78 1__ _ _ _ _ _ _ _ _ _ _

00.09

u.6

.52 ----

.52 ---

-' Lu

5- .42

1.0 1.2 1.4 1.8 1.8 2.0 2.2 2.4*PRESSURE RATIO P/

Figure 61. FAN CASCADE THRUST REVERSERVELOCITY COEFFICIENT

118

1.10

,, 0

o i.02

J-

10

8 .0 .84

.80

000w

*1 ~ .72

1.0 1.2 1.4 1.6 1.8 2.0 2.2

PRESSURE RATIO 0 PTAVE/Poo

Figur&62: FAN CASCADE THRUST REVERSERDISCHARGE COEFFICIENTAIRFLOW MATCH

119

,~.----~W

4CVu<~

10w

-CC

>C'~cc

<IIX IIa~a~o+

LLU

I~ <~

LU

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120

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5. A surveyof the cascade exit total pressure showed thatt, he exihaust flow was fairly uniform, except at thecascade" rows nearest the top of the model and to theside of the model, (Figure 64). Tailoring'-of theinternal geometry adjacent to the cascade would improvethe reverser performance.

Engine Stability Assessment

An analysis of the supply duct internal static pressure datawas conducted by Pratt & Whitney Aircraft to assess the ductpressure distortion on engine operation. Fan/compressor backpressure distortions caused by asymmetric thrust reversing isrecognized as a potentially significant destabilizing effect.The resulting loss of engine stability margin is a function ofmagnitude and extent of back pressure distortions and corre-sponding fan/compressor sensitivities with correlations normallybeing derived from test data. The test data required to estab-lish these correlations are fan exit total pressure profilea measurements. Since velocity distortions are influenced by

the presence of a fan and compressor in the system, quantitivepredictions of performance change cannot be made. However,velocity distortion measurements are a good indication of flowquality and are useful in evaluating various reverser/deflectorschemes relative to upstream flow field effects.

oAn assessment of the destabilizing effect of a velocitydistortion in a clean duct can be made only if the influenceof the fan/compressor on the velocity distortion is ignoredand percent velocity disto;xtion is assumed equal to percenttotal pressure distortion. With this in mind, the pressure

0 data was used to calculate the velocity distortion at alocation upstream of the reverser, considered representativeof the fan exit plane (x/h - 3.00). The distortion generatedby the reverser and propagated upstream is assumed to be 1800in extent and the data taken in the low and high velocityflow regions is assumed to be representative of the flow

G within their respective segments.Vmax-VminThe reverser teat data shows a velocity distortion VaVg

of 15 percent plus over a range of duct Mach number typicallyfrom low to high engine power setting. This is consideredto be significant level of distortion.

Reverse has been previously identified as a critical stabilityoperating condition for STOL aircraft engines. For examplewhen all destabilizing effects imposed upon a STOL aircraftengine during reverse operation were taken into account ina recent stability assessment, a back pressure distortion

121

STATIONS

IAVGIa .

1 2 3465 6 7 8 9 1 11

1.0I

.9.

> 8

.7I

.6

0 .4 .8 1.2 1.6 2.0 2.4

AXIAL STATION - X

Figure 64: CASCADE EXIT TOTAL PRESSURE SURVEY-BLOCKER DOOR ANGLE - 900

122

RADIAL . .STATIONS " ,_

0 PTAVG/Poo 10

2 3 4 5 6 7 8 9 10 11 12

1.0 .

r

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.8.I I

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0 .4 .8 1.2 1.6 2.0 2.4

AXIAL. STATION - X

5Figure6' CASCADE EXIT TOTAL PRESSURE SURVEY-BLOCKER DOOR ANGLE = 900 (Continued)

123

RADIALSTATIONS..

4A

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1 2 3 4 5 6 7 8 9 10 11 12

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+ . Ii.9

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AXIAL STATION - XFigure 64: C, SCADE EXIT TOTAL PRESSURE SURVEY-

BLOCKER DOOR ANGLE = 900 (Concluded)

124

,'I = •

. I.representative of 10%A Pt/Pt was accommodated by oversizingthe reverser cascade. Distortion levels greater than 10%cannot be further accommodated without excessive performancepenalties, however trades of performance and/or weight pen-alties (increased duct length for distortion attenuation)for stability can be negotiated.

It has been pointed out that it is not currently possible toquantitatively equate loss in stability margin with measur.dvelocity distortion in a clean duct. This is primarily dueto interactive effects of the upstream fan/compressor withthe downstream velocity distortion. The velocity distortionamplitude will change and will be exhibited as both a staticand total pressure distortion when a compressor characteristicand the magnitude of the distortion and is not currentlypredictable.

3.1.2 External Deflector/Target TR/TV Model Test

Details of the external deflector/target TR/TV design areshown in Figure 35. The TR/TV system consists of threef movable panels with a common hinge. During thrust vectoring,the middle panel is rotated clockwise to deflect the~exhaustflow. During thrust reversal, the inner panel rotates tothe bottom of the nacelle to block the deflected flow andthe outer panel is rotated to expose flow area at the topof the nacelle to block the deflected flow and the outerpanel is rotated to expose flow area at the top of then&acelle for the reverser exhaust. The concept may be usedfor either single pod or dual pod installations.The optimum deflector design will be a correct combination ofdeflector setback distance from the nozzle exit and theentrance flow Mach number as determined by the nozzle diameter.Provisions will be required to increase nozzle throat area toreduceri thr ver f low cntrol the deflectoareduring thrust vectoring. Flow control must be maintained atthe deflector exit in order to avoid losses associated withhigh Mach number turning.

Ob j ectives

A - The objectives of the static test are to:

1. Obtain thrust vectoring performance data as a functionof the following parameters:

o deflector setback distance12

F 125

o turning Mach number

o deflection angla

o nozzle pressure ratio

2. Evaluate the thrust reverser performance of the modelgeometry corresponding to the optimum geometry forthrust vectoring.

3. Establish design criteria for future wind tunnelmodels and for full scale hardware design.

Test Models

A schematic of the external deflector/target TR/TV modelinstallation is shown in Figure 6:. A total of 25 externaldeflector configurations were tested. Table XI lists theconfigurations and their respective geometric variations asdefined by Figures 66, 67, and 68.

The external deflector model was tested in three basic modes:

1. cruise mode

2. thrust vectoring mode

3. thrust reversing mode

over the nozzle total to ambient pressure ratio range of 1.2to 2.2. Thr cruise nozzle configuration, Dn/D = 1.0, estab-lished the baseline thrust and mass flow characteristics ofthe model used to compute thrust vectoring efficiency, thrust'everser efficiency, and airflow match for the vectoring andreversing model configurations.

The initial thrust vectoring mode runs tested the model in thefully deflected position to determine the effect of deflectorsetback distance, S, and entrance Mach number on vectoringperformance and to determine the required setback distancecorresponding to the maximum effective vector angle and airflowmatch conditions, The setback distance was held constant fortri remaining vectoring mode runs, while deflector positionwas varied to determine vectoring performance at intermediatedeflector positions. Also, the nozzle diameter was varied todetermine the required schedule of nozzle diameter versusdeflector position. Photographs of the vectoring model areshown in Figures 69 and 70. The reverser model, shown inFigure 71 was tested at the setback distance corresponding tooptimum performance gor the vectoring model.

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+100 +.187 1.0,1.15, 1.225 1.030

+360 +.500 1.0, 1.15, 1.225 1.0 -- a--.2.0

Figuro 66: EXTERNAL DEFLECTOR GEOMETRYVECTOR MODE

129

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1.870R ,.

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Figure 68 EXTERNAL DEFLECTOR GEOMETRY-REVERSE MODE

131

Figure 69: EXTERNAL DEFLECTOR TR/TV MODEL (SID 1.03 4 = 70)

R-•eproduced from132

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Figure 70: EXTERNAL DEFLECTOR TR/TV MODEL (SID 1.034 360)

133

WC

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Figure 71: EXTERNAL DEFLECTOR THRUST REVERSER MODEL

134

Model total pressure was measured using a 10 probe "area-weighted" total pressure rake located in the air supply

S duct upstream of the test model. A chromel alumel therom-couple installed in the duct adjacent to, and in the sameplane as the total pressure probe monitored model flowtotal temperature. Static pressure taps were installed nearthe throat of the test nozzles as shown in Figure 66. Thesepressures were used to determine the flow Mach numberentering the deflector.

Test Results

Results of the external deflector/target TR/TV model test aresummarized below. Detailed results are contained in Reference 11.

1. Vectoring performance was very sensitive to nozzlepressure and deflector geometry. Small changes inpressure ratio setting (Figure 72) and in thedeflector setback distance and deflector rotationS~position had significant effects on the vectoring

efficiency and airflow match characteristics.(Figure 73, 74, 75, 76, 77, 78)

2. Optimum vectoring efficiency at P T/Pb = 1.6 was

nV = 0.88 with an effective vector dngle (eff = 660at airflow match conditions. The vectoring perfor-mance was lower than the performance goal of nv = .90and aeff ' 750 indicating that the deflector designshould be revised.

3. Optimum vectoring performance occurred when the flowMach number at the entrance of the deflector wasapproximately MENT = 0.45 (Figure 79).

4. The thrust reverser performance evaluation showedthat the reverser efficiency and airflow match werealso sensitive to nozzle pressure ratio (Figere 80).Reverser efficiency at P T/Pa = 1.60 varied between34 to 41% depending on the nozzle diameter. Airflowmatch data indicated the reverser was significantlyunder area and that modifications to the deflectorgeometry would be required to improve the reverserairflow match characteristics (Figure 81).

135

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Figure 72: VECTOR EFFICIENCY (r'1w AIRFLOW SIATCLI ( $ )Dn/D = 1.225 S/D = 1.033 Y/D =.50

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1.0 1.2 1.4 1.6 1.8 2.0 2.2SETBACK RATIO • S/D

Figure 73: EFFECT OF SETBACK RATIO ON VECTOR EFFICIENCYAND AIRFLOW MATCH Dn/D = 1.0

137

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1.0 1.1 1.2 1.3 1.4 1.5 1.6

SETBACK RATIO -" S/D

Figure 74: EFFECT OF SETBACK RATIO ON AIRFLOW MATCH

D,/D = 1.225 Y/D =.50

138

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SELECTED SETBACKRATIO TO OBTAIN

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1.0 1.1 1.2 1.3 1.4 1.5 1.6

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139

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DEFLECTOR ROTATION ANGLE -

Figure 76. EFFECT OF DEFLECTOR POSITIONON AIRFLOW MATCH, PT/Po = 1.60

140

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1.0

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w __

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LL,ۥ ~CRUISE ","

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I MAXDFPýECTOR

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DEFLECTOR ROTATION ANGLE -

Figure 77: EFFECT OF DEFLECTOR POSITION

ON VECTOR EFFICIENCY, PT/Poo = 1.60

141

80 'O" n/D 1.0

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-.225

so-U.

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U.

CRUISE20 POSITION - 1.60.I /PTSID = 1.80.

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DEFLECTOR ROTATION ANGLE "

Figure 76: EFFECT OF DEFLECTOR POSITIONON EFFECTIVE VECTOR ANGLE

142

1.oon .. m $ 1 -/On1.00 ____

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AVERAGE ENTRANCE MACH NUMBER MENT

Figure 79: EFFECT OF ENTRANCE MACH NUMBER

ON CORRECTED VECTOR EFFICIENCY

143

.90

.88

.86

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0.0 1.2 1.4 1.6 1.8 2.0 22 2.

NOZZLE PRESSURE RATIO PT/P-o

Figure 80: REVERSER EFFICIENCY MR) AIRFLOW MATCH (C)

Dn/D = 1.225 S/D = 1.03

144

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Figure 81: THRUST REVERSER PERFORMANCE CHARACTERISTICS

145

Further details of the test models and installation, instru-mentation, procedure, and results of the fan cascade thrustreverser model and external deflector/target TR/TV modelstatic tests are presented in Reference 5.

3.1.3 Overwing Target Thrust Reverser Data Review

Static performance for an overwing target thrust reverser de-sign were obtained during a Boeing sponsored static test pro-gram. Thrust reverser efficiency and airflow match character-istics were investigated with a small scale model on the BoeingThrust Vectoring Test Rig. Figure 8Z shows a schematic ofthe reverser model and photographs showing the model installedon the test rig are presented in Figures 83 and 84 . The modelwas tested with separate fan and primary mass flows and pressureratios simulating. a high bypass ratio turbofan engine. Geometricparameters investigated during the test included door length,lip length, door angle, reverser door setback distance, and ductshape. Data correlations for reverser efficiency and airflowmatch for the reverser model are discussed in the followingparagraphs.

Reverser efficiency data corresponding to the engine take-offpower setting are summarized in Figure 85 As discussed inVolume I , a parameter that provides satisfactory correl-ations of target thrust reversers performance is # - 6, thedifference between the reverser door blockage angle, #, andthe reverser door angle, 8 (see Figure 82). This parameterwas successfully used to correlate annular target thrust reverserperformance and was applied to the overwing external targetthrust reverser data.

The correlation -*'wn in Figure 85 indicates that the reversergeometry should p Aide for a net angle 0- 6 of approximately-25° to achieve 5• percent reverser efficiency. It should benoted that the correlation seems to provide best agreementwhen the door angle is constant and the lip geometry and setbackdistance are varied to establish the blockage angle. The doorangles for doors 10 and 11 were 93° while the other configura-tions had a door angle of 780. This characteristic was alsonoted for annular target thrust reverser correlations pre-sented in Volume I.

146

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Experience with the annular target thrust reverser showed thatthe parameter, 0 - 8, did not satisfactorily correlate airflow

0 match data. Similar results were obtained for the overwingtarget thrust reverser model as shown in Figure 86 for theprimary nozzle flow data. Considerable data scatter occurredthat was dependent on the reverser door geometry. However,modifying the airflow match data by the ratio of the nozzleheight, h, and door opening, 1 , considerably reduced thedata scatter as shown in Figure 87. A similar correlationof fan airflow match data is shown in Figure 88.

As noted for the reverser efficiency correlation, the airflowmatch correlation seems to work best when the door angle isconstant. The door 5 data with single flags are for a doorgeometry with a longer lip then the other configurations.This data would indicate that a correlating parameter thatincludes the lip geometry might provide a better correlatingparameter.

3.2 -- Task 3.2 C,.ýrrect Data to Full Scale Performance

The objective of Task 3.2 was to correct the scale model per-formance data obtained during Task 3.1 using scaling relation-ships to predict full scale performance. A brief review was

S1conducted of the literature collected during Part 1A of theprogram and other existing data. Only two significantreferences were fniund that pertain to scaling nozzle perfor-mance, Reference 12 and 13. The first report describes ananalytical methoc .;o scale nozzle velocity and dischargecoefficients. The method employs the turbulent, compressibleboundary layer analysis of Stratford (Reference 14 Byassuming the losses are due entirely to skin friction andare a function of Reynolds number and geometry (at a givennozzle pressure ratio) the influence of Reynolds number onvelocity coefficient is given by the following equation:

IN- [ W2CVIL(5CM,1)'V (i MX * V4tj

CvF - • •M/I-\CNzN .v~

where N is the turbulent boundary layer exponent (typicallyN = 7 for a turbulent boundary layer), and the subscripts MSand FS refer to model scale and full scale. The influence ofReynolds number on discharge coefficient is given by thefollowing equation: /

I- (Reps) 11-COMS)

151

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S/..

U.0

aa~ it;,

4i . . ...-. - -- So o C

o 00<0,•60 a

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152

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1533

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z

/

153

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The effect of Reynolds number on velocity coefficient is showngraphically in Figure 89. Nozzles with high velocity coeffi-I c'.ent are affected less by Reynolds number than nozzles havinglow velocity coefficients. Since the full scale Reynoldsnumber, ReFS, is usually greater than ReMS, the full scalevelocity coefficient is usually greater than the model scalV CV.

Q A comparison of theoretical and experimental velocity coeffi-cients at several Reynolds numbers is shown in Figure 90. Thesolid lines were calculated from Equation (1) by matching theCV at a Reynolds number ratio of 1.0.

Reference 14 presents test data illustrating Reynolds numbereffects on nozzle performance coefficients. These data werecompared to predictions made using Equations (1) and (2) withfavorable results. For example, the effect of Reynolds numberon ASME nozzle discharge coefficient is shown in Figure 91.

Several references were found containing comparisons betweenmodel and full scale TR and TV performance parameters (Reference15 to 23). Comparisons for corrected reverser efficiencyare shown in Figures 92 to 96. In most cases the model scale,fficiency is greater than full scale. The difference inperformance is usually attributed to exhaust gas leakagethrough full scale tail pipe gaps and thrust reverser seals.Model scale test hardware freqnently does not scale gaps andseals accurately. In some cases differences between modeland full scale values were due to geometric differences.For example, data taken for the full scale target reverserEhown in Figure 96 was obtained with a greater setback thanfor model scale.

The existing data indicates that scaling of thrust reverserairflow match characterist 4ics is not always successful. Forexample, differences were not i between the Model 737 targetthrust reverser model and f scale primary and'fan airflowmatch characteristics. Full cale airflow match showed anappdrent increase in fan flow and decrease in primary flowduring reverse operation.

Comparisons between combined fan and primary airflow (Figure 97)indicates that model scale data predicts full scale airflowmatch only within + 2%. Final tailoring of airflow match inreverse thrus. musE bE lone at full scale. However the modeldata are useful in predicting large mismatch characteristics.

A comparison of model and full scale performance for a hingedspherical deflector nozzle in the cruise mode is shown inFigure 98. N_-iuniform jxit flow conditions for the full scalenozzle degraded predictions of nozzle coefficients and contrib-uted to the observed discrepancies.

155

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15.

u10U6

U.

w

0.90 0.92 0.94 0.96 0.98 1.00

VELOCITY COEFFICIENT AT MODEL SCALE, CVMS

Figure 89: SCAl ING EFFECTS OF REYNOtDS NUMBERON VELOCITY COEFFICIENT

156

Q NOZZLE 1 DATA, REFERENCE 24El NOZZLE 2 DATA, REFERENCE 24- THEORY OF REFERENCE 12 MATCHED

TO REYNOLDS RATIO OF 1.0

0.99.

NOZZLE 2

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09

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REYNOLDS NUMBER RATIO, ReFS/ReMs

Figure 90: COMPARISON OF THEORETICAL AND EXPERIMENTAL EFFECTSOF REYNOLDS NUMBER ON VELOCITY COEFFICIENT

157

N

414

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REFERENCE 19, MODEL SCALE (0.3)

FULL SCALE

U

0.6

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w /

li/Il /

� �w

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NOZZLE PRESSURE RATIO, P2N0 2.~TN'-oo

Figure 92: COMPARISON OF MODEL AND FULL SCALE

CORRECTED REVERSER EFFICIENCY DATAFOR A CASCADE THRUST REVERSER

159

Reprodu-ed frombest ov,;lable copy.

MOlDEL SCALE (0.057), REFERENCE 17-.. - -FULL SCALE, REFERENCE 16

()

THRUST REVERSER INSTALLATION 0

0.7 CASCADE DETAILS

0.6

0.5I u

O.5wA

0u.

" 0.4

01 i

uJ

w0

I- CA

CORCE REESREFCINYDWA

0.2

0.1

,it FOR THE C-5A FAN CASCADE REVERSER0160

REFERENCE 18

- MODEL SCALE (0.25)FULL SCALE

/dn- 0.621O

0.7

U 0.6

~0.5

B,0 j ./C.1

2 /w -u 0.4 3U. -u. /

(nn

uJ 0.1

w U,

0C

60.1

S1.0 1.5 2.0 2.5

I, NOZZLE PRESSURE RATIO: PTN/Poo

Figure 94: COMPARISON OF MODEL AND FULL SCA LECQr" ECTED REVERSER EFFICIENCY DATA

F3 A HEMISPHERICAL TARGET REVERSER

161

REFERENCE 20MODEL SCALE (0.154)

"" "" " FULLSCALE

FORWARD THRUST POSITION REVERSE THRUST POSITION0.7

0.6 I

/0, .5 I

zI

S0.4

S0.3a w I

80.2/ _ _ _ _ _ _ _ _ _ _

/V/

0.1

01.0 1.5 2.0 2.5

NOZZLE PRESSURE RATIO, PTN/Poo

Figure 95: COMPARISON OF MODEL AND FULL SCALEC•ihF.. TED REVERSER EFFICIENCY DA TAFOR A TARGET THRUST REVERSER

162

REFERENCE 15MODEL SCALE (0.106)

rn--.. FULL SCALE

0.7

4,!,

0.6-SI

0.6.

U.m_0.4

L.

cc• 0.3U. -w>

CCaS0.2

, 8

0.1

01.0 1.5 2.0 2.5

NOZZLE PRESSURE RATIO, PTN/Poo

Figure 96: COMPARISON OF MODEL AND FULL SCALE

CORRECTED REVERSER EFFICIENCY DATAFOR THE 737 TARGET THRUST REVERSER

163

REFERENCE 15MODEL SCALE (0.108)FULL SCALE

1.01

1.0

- 0.99! -

'u. 0.98

0.97

1.0 1.5 2.0

NOZZLE PRESSURE RATIO P PTN/Poo

Figure 97: COMPARISON OF MODEL AND FULL SCALEAIRFLOW MATCH DATA FOR THE MODEL737 TARGET THRUST REVERSER

164

REFERENCE 23MODEL SCALE (0.23FULL SCALE

1.0

L' i 0.9 "" - "......

CC

z/Eo.9

(4 ~U.

0

w0.8,

IL

0.1 . 1 . . .

0.7 ,

1.0 1.5 2.0 2.5

NOZZLE PRESSURE RATIO PTN/Poo

Figure 98. COMPARISON OF MODEL AND FULL SCALEPERFORMANCE FOR A SPHERICAL EYEBALL NOZZLE

165

Unfortunately, none of the reports noted above generalizedscale effects to predict thrust reverser or thrust vectoringnozzle performance parameters, i.e., reverser efficiency, n R'vectoring efficiency, n , or airflow match, f. Therefore,the following approach wXs taken to satisfy the objectivesof Task 3.2. The scaling relationships for Cv and CD givenEquations (1) and (2) were programmed into the TR and TVSystem Performance Program (TEM-357) developed during Part 1A.Scale corrections are made (at the users discretion) to thefollowing types of nozzles:

(1) Cruise nozzles

a) Conical

b) Annular

C) Irregular shaped nozzle

(2) Thrust vectoring nozzles

a) Single bearing

b) Three bearing

c) Spherical eyeball

d) Lobstertail

The changes in program input required for scale correctionswill be discussed in the Final Report.

3.3 -- Task 3.3 Correlate with Existing Model Data

The objective of Task 3.3 was to correlate the data obtainedduring Task 3.1 with the data developed during Part 1A of theprogram. The approach taken to fulfill this objective was toanalyze the data and incoporate the significant datacorrelations into the Internal Performance Module of TEM-357.As noted in Volume I existing external deflector data werefound inadequate to predict effects of setback and door lengthratio. Theoretical results were shown illustrating the effectsof external deflector geometric parameters. However, thetheoretical results showed considerable disagreement withtest data and were therefore not included in the subroutineused to predict external deflector performance. Instead, twospecific sets of data were used to predict external deflectorperformance, one for flat plate and the other for curveddeflectors.

166

9

In order to assess the effects of deflector setback, experi-mental data obtained fr6m the hinged external deflector •estwere analyzed and correlated in terms of simple geomet%parameters. A correlation for discharge coefficient rco asa function of setback ratio is shown in Figures 99 to 101.Seventeen TV and three TR configurations correlated using thesetback ratio parameter. Correlations attempted in terms ofother geometric parameters resulted in greater data scatter.

A correlation for corrected vector efficiency is shown inFigures102 to 1Q4.For setback ratios X/D > 1.0, the differentconfigurations correlate on a single line. For setback ratiosX/D 4 1.0, however, the data correlation branches into twocurves, an upper curve for deflection angles of approximately

U 10 degrees and a lower curve for deflection angles of 30degrees.

Efforts to develop a general dita correlation for the threetypes of external deflectorc, (flat, curved, and hinged) werenot successful. For example, discharge coefficient ratioU correlations are compared on Figure 105 for annular target

thrust reversers, the hinged external deflector and theoryfor a flat plate deflector. Because of the lack of correlationbetween different types of TR and TV configurations, the hingeddeflector data correlations were incorporated into the externaldeflector subroutine of TEM-357 as a separate option. It is

U believed that the effects of setback ratio are adequatelycovered by the hinged deflector data correlations.

167

NOZZLE PRESSURE RATIO - 12

0 THRUST VECTORING NOZZLE CONFIGURATIONS

STHRUST REVERSER CONFIGURATIONS

1.0

0A

i: 0.7/0.

( 0.6z •I Ib~-4-4

0.5

0.5 1.0 1.5 2.0

SETBACK RATIO, X1/D, OR /Dn

Figure 99: DISCHARGE COEFFICIENT CORRELATION

FOR HINGED EXTERNAL DEFLECTOR, P0/p0 1.2

168

It

NOZZLE PREMSJRE RATIO = 1.6

0 THRMST VECTORING NOZZLE CONFIGURATIONS

10 THRUST REVERSER NOZZLE CONFIGURATIONS

1.0.I

I _ _ __0.8

t.,

L.u

Uw

~0,6 -

0.5

0.5 1.0 1.5 2.0

SETBACK RATIO, XIDn OR , /Dn

Figure 1W: DISCHARGE COEFFICENT CORRELATION FORHINGED EXTERNAL [.EFLECTOR NOZZLE ,P/ P 1.6

169

NOZZLE PRESSURE RATIO M2.2

0 THRUST VECTORING NOZZLE CONFIGURATION

() THRUST REVERSER NOZZLECONFIGURATIONS

1.0.

r00.9

Ji0.

Lz

0.51

0.5 1.0 1.5 2.0

SETBACK RATIO, X/ID OR /Dn

Figure 101: DISCHARGE COEFFiCENT CORRELA T!ON FORHINGED EXTERNAL DEFLECTOR NOZZLE, PT/Pm 2.2

170

1.0

0

S0.9

LU 30P

w C.U.

0> 0

wcc

08

X --

0.7

g8

0.5 1.0 1.5 2.0

SETBACK RATIO - X/Dn

Figure 702: CORRECTED VECTOR EFFICIENCY CORRELATIONFOR HINGED EXTERNAL DEFLECTOR NOZZLES PT/P, = 1.2

S•. Z • . . .. . . . .. .. .. . .. . . .. . . .. .... .. . ...

, " .. ... . . . . . ... .. ... .. ... .

•r "

1.0-

z

w 1.000

0.7

O J5 1.0 1.5 2.0

SETBACK RATIO X/Dn

S~Figure 103: CORRECTED VECTOR EFFICIENCY CORRELATIONFOR HINGED EXTERNAL DEFLECTOR NOZZLES, PTIPo,, 1.6

~172

a

00

' 0

t 0\w 0

0.80.5 -. 0-5 .•

L~r~i 10

j ).

wcc

a C)

to.8x -4

0.7 4

SETBACK RATIO, X/D.

Figure 704. CORRECTED VECTOR EFFICIENCY CORRELA TIONFUR HINGED EXTERNAL DEFLIEFCTOR NOZZLES, P1 ýý-/ =2.2I 173

DATAREF i DATA VOLI THEORY.VQLI"HINGED EXTERNAL "ANNULAR TARGET "No MITRE SENDDEFLECTOR' THRUST REVERSER"

-' - - a -'°°

o 1

'• • 0.7

S• o.a ..... _ _ __ _0.7 4

4, -- -Lu

0 Ia

0.5

0.5 1.0 1.5 2.0 2.5 3.0 3.5SFTBACK RAg;O XfH OR C/H

Figure 105: COMPARISON OF DISCHARGE COEFFICIENT RA TIO

DATA CORRELA TeONS

174

SECTION IVG

CONCLUSIONS AND RECOGiMNDATIONS

4.1 Part IB - Design

The design tasks conducted during this study have producedsveral thrist reverser and thrust vectoring concepts applicableto the high lift systems likely to be used on STOL tacticaltransport aircraft:

1. Externally blown flap (EBF)

2. Mechanical flap and vectored thrust (MF + VT)

3. Upper surface blowing (USB)

In addition, a detailed design for a fan cascade thrust reversersystem that meets the requirements of airflow match, performance,and flow directional control to minimize exhaust flow reingestionand aerodynamic interference effects was completed. The variousTR and TV concepts were evaluated on the basis of internal perform-ance, weight, and aerodynamic stability'and control characteristicsto select test models for static performance tests conducted duringPart IC. The primary conclusions to be drawn from the design studyinclude the following:

1. The aircraft high lift system has a significant impacton the thrust reverser or thrust vectoring system. Eachhigh lift system has unique propulsion system installationrequirements that affect the thrust reverser or thrustvectoring system design.

2. To avoid the problems of reingesticn and foreign objectdamage during the stopping ground roll, the reversersystem must have the capability of controlling the direc-tion of the exhaust flow. There are few regions in wh,.chthe reverser exhaust can be directed:

a) Upward and forward above the nacelleforward of the wing leading edge

b) Outboard of outboard nacelle

c) Above the wing aft of leading edge

d) Aft of wing trailing edge

Of these four regions, the best solution consistent with apractical reverser design is to direct the flow upward andforward above the nacelle forward of the wing leading edge.

175

3. Thrust reverser systems for unmixed flow engines may or maynot use a primary thrust spoiler depending on the enginebypass ratio. The following general guidelines were estab-lished:

a) Bypass ratio 3.0 unmixed flow engines requirethrust reversers for both the fan and primaryflows.

b) A mechanical spoiler may be used to spoil theprimary thrust of bypass ratio 6.0 unmixed flowengines.

c) A mechanical spoiler is recommended to spoilthe primary thrust of bypass 12.0 unmixed flowengines. The spoiler may be eliminated providedthe fan reverser efficiency is at least 50%.

4. "Cycle spoiling" of the primary thrust could provide asimple and lightweight reverser system for a mixed flow-engine, and appears to be an attractive installation whencombined with a thrust vectoring system. However, theoverall reverser effectiveness is dependent on the enginebypass ratio, and the controlling area of the primary flowduring reverse operation. The over area condition of theprimary flow determines the primary thrust spoiling effect."Cycle" spoiling would require interstage bleed for fan-high-low compressor engine configurations because of lossin low pressure compressor surge margin.

5. Landing field length studies conducted during the programshowed that the reverser delay time and the reverser cutoffvelocity are the significant parameters that determine thelanding roll distance. The field length studies also showedthat an optimum reverser system for a STOL tactical trans-port would have a zero delay time, less than 20-knot cutoffspeed, and reverser effectiveness greater than 35%.

6. Combining the thrust reverser system and thruist vectoringsystem for a mechanical flap + vectored thrust lift systemis a difficult design task. The options available to thedesigner are either to 1) combine the functions of thrustreversing and thrust vectoring into a single mechanism or2) separate the thrust reversing and vectoring functionsand provide a complete design for each system. The firstoption is perhaps the most desirable because of potentialweight savings and reduced support systems required, butis complicated by increased mechanical complexity, by thereverser exhaust directional control requirements, and byaerodynamic interference effects. For example, a combinedthrust reverser/vectoring system must place the reverserexhaust forward of the wing leading edge to obtain thedesired flow directional control. However, the requirementsmean that the thrust vector is forward of the airplane center

176

gravity while dire-otional control of the fan reverserexhaust can be achieved.

() 7. The following conclusioAs were made based on performanceand weight evaluation results:

a) The thrust reverser system for externally blown flaplift systems will probably involve the use of a fancascade thrust reverser.

b) Mechanical flap and vectored thrust lift systemsczould use either

a. rotating nozzles

Sb. multibearing vectoring nozzles

c. external deflector/target thrust vectoring/reversing systems

depending on the type of engine cycle (mixed orunmixed flow). The rotating nozzle vectoring systemwould be used for unmixed flow engines and would"present airplane balancing problems due to the thrustvector location and a resulting adverse pitchingmoment. The external deflector/target TR/TV systemwould also pose balancing difficulties but to alesser degree. Multibearing vectoring nozzle instal-lations would present no airplane balancing problems.

c) Upper surface blowing lift systems will utilize anexternal target thrust reverser system installedwith a mixed flow engine.

8. Static performance tests and future wind tunnel investiga-tions should include the following thrust reverser andthrust vectoring systems:

a) fan cascade thrust reverser systems (EBF, MF + VT)

b) external deflector/target TR/TV system (MF + VT)

c) multibearing vectoring nozzle (MF + VT)

d) external target thrust reverser (USB)

Recommendations related to thrust reverser and thrust vectoringsystem design include the following:

1. Future studies of TR and TV systems should include detaileddesign studies of the thrust reverser and thrust vectoringsystems considered during Part IB. The design studieswould be based on the results of the Part IB design resultsand would emphasize the system mechanical design requirements,

177

structural life requirements, and safety and reliabilityrequirements.

2. Future design studies should include trade studies of:

b a) TX/TV subsystems including

1) controls - manual vs. automatic pneumatic vs.ii hydraulic

2) interlocks - engine, flight controls, landinggear

3) failsafe - redundancy, interlocks

b) Noise suppression vs. no noise suppression.

4.2 Part IC - Model Test

The model static performance tests conducted during Part IC of theprogram have resulted in parametric test data for a fan cascadethrust reverser system and an external deflector/target combinedthrust vectoring and reversing system. These data plus existingdata for multibearing nozzles and an external target thrust reverserwill be useful to define the performance characteristics of theseTR/TV systems and provide guidance for future wind tunnel modeland full-scale design criteria. The primary conclusions of themodel tested conducted during Part IC include:

1. Reverser efficiency of at least 50% is possible for a fancascade thrust reverser that exhausts all of the flow throughthe upper portion of the nacelle. The highest reverserperformance was obtained when the duct blocker door anglewas 1350.

2. Internal flow distortion can be expected when the fanreverser is located in the upper 1800 segment of the nacellethat could effect the fan surge margin during reverseroperation depending on the spacing between the fan exit andthe reverser. The re'erser should be located at least threetimes the fan exhaust duct height downstream of the fan exit.

3. Careful tailoring of the internal duct geometry adjacent tothe fan cascade reverser would probably improve the reverserefficiency.

4. The external deflector/target TR/TV performance was verysensitive to small changes in nozzle pressure ratio setting,and deflector geometry.

51 The external deflector/target TX/TV system design must berevised to improve vectoring performance and to increasethe effective vector angle. Also, the design must be revised

178

to improve the airflow match, characteristics during reversethrust mode. The impact of the design modifications on thetotal system design including weight, and mechanical com-plexitymust be considered.

6. Optimum vectoring performance occurs when the controllingarea, is located at the deflector exit and the entranceMach number- of the flow entering the deflector is Mach .45.

O Recommendations for future static performance and wind tunnelmodels include the following:

1. Future static performance tests of fan thrust reversersshould provi.de a degree of simulation of the fan exhaustvelocity profiles to assess the effect of the internal

Liflow distortion on the fan performance.

2. Future test model geometry should reflect the results ofthe detailed design work recommended in Section 5.1.

179

REFERENCES

1 "Medium STOL Transport, A Feasibility Study fora Prototype Development Progzam," D162-10052-1,The Boeing Company, June 1971.

2 "Preliminary Performance Estimates of CommercialSTOL Transport Turbofan Engines, STF 342 Series,"TDM-2177, Pratt & Whitney Aircraft, April 1969.

"3 "Preliminary Performance Estimates of STF 344Turbofan Engine," TDM-2190, Pratt & WhitneyAircraft, October 1969.

Hatley, J. P., "A Simplified Method for RapidCalculation of Off-Design Performance of Turbojetor Turbofan Engines at Subsonic Flight Conditions"

WI(TE-022), D6-5423, Part I, The Boeing Company,1962.

5 Mount, J. S. and Lawson, D. W. R., "Developing,Qualifying, and Oprating Business Jet ThrustReversers". SAE Paper 690311, March 1969.S6 Cecil, D. J., "Program Usage Instructions forComputer Program TEM 36D, Landing Roll Study",AMEP-M-354A. The Boeing Company, April 1972.

7 Wood, S. K. and McCoy, J., Design and Control ofthe 747 Exhaust Reverser Systems", SAE Paper 690409,April 1969.

8 Petit, J. E., 'STOL Transport Thrust Reverser/Vectoring Program Supplemental Test Report,"D180-14801-1, The Boeing Company, 1972.

9 AMST Technical Data - Propulsion, D162-10069-4,Vol. 2, The Boeing Company, May 1972.

10 Petit, J. E., "STOL Transport Thrust Reverser/Vectoring Program, Part 1C Test Plan,"D180-14970-1, The Boeing Company, April 1972.

180

REFERENCES

11 Petit, J. Z., "STOL Transport Thrust Reverser/Vectoring Prograzt, Part IC Test Report,"D180-15194-1, The Boeing Company, October 1972.

12 Hiatt, D. L., The Analytical Velocity CoefficientCalculation of an Annular Nozzle, and The Effect ofReynolds Number on Velocity Coefficient, D6-20355TN,The Boeing Company, November 1967.

13 Wear, D. E., Reynolds Number Effects on Nozzle Perfor-"K mance, General Electric Coordination Memo No. B-70-11p

Auaust 1970.

14 Stratford, B. S., The Calculation of the DischargeCoefficient of a Choked Nozzle and the Optimum Profilefor Absolute Airflow Measurement, Journal of theRoyal Aeronautical Society, Vol. 68, April 1964.

15 Neal, B., Comparison of Model and Full Scale Test DataObtained During the Development of a Target ThrustReverser for the 737 Airplane, The Boeing CompanyCoordination Sheet No. 737-PPU-928, February 1968.

16 Preliminary Study Data Thrust Vectoring and ThrustReverser System, General Electric Report R70AEG336,August 1970.

17 Poland, D. T., The Aerodynamics of Thrust Reverser forHigh Bypass Turbofan, AIAA Paper 67-418, July 1967.

18 Kohl, R. C., Performance and Operational Studies ofa Full Scale Jet Engine Thrust Reverser, NACA TN 3665,April 1956.

19 Kohl, R. C. and Aigranti, J. S., Investigation of aFull Scale, Cascade Type Thrust Reverser, NACATN 3975, April 1957.

20 Hawk, G. W., Summary of the Development of MechanicalType Thrust Reversers, WADC Technical Report 57-17,May 1957.

21 McDermott, J. F. Jr., Summary of the Development ofAerodynamic Type Thrust Reversers, WADC TechnicalReport 57-18, May 1957.

181

*'t

22 Pickered. J. C., Selection and Design of ThrustReve:rsers for Jet Aircraft, IAS Paper No. 60-77,June 1960.

23 Carlson, N. G., Development of Flight Weight DeflectionDevice and Actuation System for the TR30-P-8 Engine,Final Report, Pratt & Whitney Aircraft Report PWA-3266,December 1967.

24 Schloemer, J., Test Results of Reynolds Number Effectson Plug Nozzle Performance Coefficients, General"Electric Technical Brief, 70016.

I

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