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\ WADC TECHNICAL REPORT 55-124

FORMATION LIGHTS FOR FIGHTER AIRCRAFT

CHARLES A. BAKER

AERO MEDICAL LABORATORY

MARICH 1955

o,-

0

N0 E14a

WRIGHT AIR DEVELOPMENT CENTER

THIS REPORT HAS BEEN DELIMITED

AND CLEARED FOR PUBLIC RELEASE

UNDER DOD DIRECTIVE 5200.20 ANDNO RESTRICTIONS ARE IMPOSED UPON

ITS USE AND DISCLOSURE,

DISTRIBUTION STATEMENT A

APFROVED FOR PUBLIC RELEASEJ

DISTRIBUTION UNLIMITED,

FORMATION LIGHTS FOR FIGHTER AIRCRAFT

CHARLES A. BAKER

AERO MEDICAL LABORATORY

MARCH 1955

PROJECT No. 7180

WRIGHT AIR DEVELOPMENT CENTER

AIR RESEARCH AND DEVELOPMENT COMMANDUNITED STATES AIR FORCE

WRIGHT-PATTERSON AIR FORCE BASE, OHIO

Carpentcr Litho & Prtq. Co., Sprrirmfield, 0.200 76 April t955

FOREWORD

This report was prepared at the Psychology Branch, AeroMedical Laboratory, Directorate of Research, Wright Air Devel-opment Center, under Project No. 7180 entitled, *HumanEngineering Application to Equipment Designs with Dr. WalterF. Orether acting as Project Engineer* The study of whichthis report is a summary was conducted at the request of Ifq*Air Research and Development Ccomand. Special acknowledgnentis given to Lto W. Dep.s Chiles for his valuable assistance inthe preparation of the manuscript, and to Mrs. Edna Miller forher assistance in locating reference material.

wADC TR 55-124

ABSTR ACT

An important consideration in the design of formation referencelighting on fighter aircraft is that the wiin; 1 lot ehould be providedwith unambiguous information about the attitude and distance of thelead aircraft. The present formation lighting system used on fighteraircraft is inadequate in this respect, and, at least partially as aresult of this, pilots frequently experience disorientation and confu-sion during night formation flight. The past research on formationlighting is reviewed and recommendations are made for modifications ofthe present formation lighting systems. These modifications utilizethe conventional navigational lighting system components. The recom-mended modifications include: (1) redesign of the wing-tip navigationlights so that they provide suitable reference lighting for wing air-craft, (2) installation of a linear light on the fuselage near thewing root, and (3) the use of a single rotary detent control knob whichprovides control for three brightnesses of formation lights, navigationlighting for cruise and Join-up, and an off position.

PUBLICATION REVIEW

This report has been reviewed and is approved.

FOR THE COMMANDER:

K iB 12&UDA Colonel, USAF (MC)

Chief, Aero Medical LaboratoryDirectorate of Research

WADC TR 55-124 111

Design Considerations for Formation Lightsooeooo.o...........o..

Present Status of Air Force Formation Lighting~.... 009*60........ 2

Past Research on Formation Lgtn...............

Recommended Formation Lighting Systems................ 6

12

LIST OF ILLUSTRATIONS

Firture Pfe-

1 Standard Excterior LightingInt la on..........

2 Alternative..Methods for Wing Tip Formation Lightingo.........

3 Recommended Ext~erior Lighting Arrangeznent..6................ 10

4 Recommended Exterior Lighting Control Knob..060............. 10

LIST OF TABLES

Table P~

I Table of Recom~mended Intensitie~s........................... 11

WIADC TR 55-1U4 iv

I. IlIMODUCTION

"Formation flight of military aircraft is justified on th'e groundsof increased mission effectivenea., even though formation flieht presentsdefinite hazards to equipment and personnel. .•ee ho.ardz becomegreater when fo:..mation flight is conducted at night or in overcast wherethe visibility of other aircraft in the formation is restricted, Onemethod of decreasing the hazards of night formnt-on flight is to useexterior reference lighting on the aircraft. Such lights should bedesigned so that the wing pilot is able to maintain formation positionwith the least effort and confusion. The purpose of this report is tooutline the type, color, intensity, arrangement, and control offormation lights that would most effectively reduce the hazards involvedin night formation flight of fighter aircraft.

II* DESIGN CONSIDERATIONS FOR FORMATION LIGHTS

The selection of any particular formation light system will dependupon many considerationsj of these, the most basic are listed below. Ofcourse, awn satisfactory formation lighting system will of necessityconsist of compromises among the various considerations.

1, ftineering considerations s

(a) Aerodynamic factors of the exterior lighting installations.

(b) Weight and space requirements of the lighting components*

-() Rlectrical demands and reliability of the lighting systems.

2. SeguritZ_ considerations .

(a) Ground to air detection by the eneuve

(b) Air to air detection by the enemy.

3. Huan factors considerations.t

(a) Suitability in providing unambiguous orientation information.

(b) Visibility of the reference lights*

(c) Dark adaptation.

(d) Confort and fatigue.

In this report, the primary emphasis is upon the human factorsconsiderations. However, the formation lighting systems recommended inthis report are selected on the basis that they be compatible with the

WADC 7R 55-12

engineering and security requiremeuLs as well as satisfy the human factorsrequirements. The recommendations must, of necessity, be genaral innature because of the radical difference3 in airframe constructioz foundamong various types of fighter aircraft. For example, fighter aircraft arebuilt with delta, with sweptback, or with straight winge!. AUho, scmeaircraft have wing tip tanks, or they may have rocket mounts. It ispossible that the types of formation patterns flown will change as afunction of the-type-of aircraft and its mtssion& Therefore, the designrecemendAetiona are kept general in order to permit thair application toaircraft which vary widely in configuration.

IIl. PRWSP2T STATUS OF AIR FORCE FORMLTION LIGHTING

The formation light arrangement on current Air Force fighter aircraftis shown in Figure 1. These formation lights are the standard navigationlights switched to a dimmed position with a steady instead of flashingexposure* Therefore, the formation reference lighting consists of the wingtip running lights, the two fuselage section lights, and the two taillights* These lights consist of filament bulbs protected by transparentshields which are faired into the aircraft surfaces. The lights thus givethe appearance of opoint' sources of light.

The important functional requirement of formation lighting is thatit provide the pilot with unambiguous information about the attitude anddistance of the lead aircraft. The present formation lights used by theAir Force are inadequate in this respect* Indeed, some of the instancesof.disoriontation reported by pilots have been attributed to these lights(8, 16)e The present formation lights may also account for some otherwiseunexplained accidents (13).. Previous evaluations of the present formationliUhti4 system have revorted it to be generally unsatisfactory (1, 12, 14),and other sources of information have indicated inadequacy. Personnel ofthe Asro Medical Laboratory, Wright Air Development Center, conducted aninterview with fifteen pilots of the 97th Intercept Squadron. Eleven ofthe fifteen pilots reported that they had, on at least one occasion, becomeconfused and disoriented during night formation flight. Several pilotsreported that such disorientation occurred frequently, and most of theeleven pilots believed that the formation lights were the cause of thedisorientation, or, at least, they believed that modifications of theformation light system would reduce the frequency of occurence of disorien-tation. All fifteen of the pilots complained about the brightnesses of theformation lights (particularly the fuselage section lights), and mostindicated a desire for a greater range of control of formation lightbrightnessese

The disorientation that pilots experience during night formationflight may result from what is called the autokinetic illusion, TheautoJkinetic illusion is a visual phenomenon in which a stationary spot oflight against a dark background appears to move erratically* It is knownto have been experienced by pilots when they were observing formationlights on other aircraft (8). In fact, this illusion can disorient a

WADe TR 55-124 2

1800

Bottomfutelage Top fuselage

S light ligh

(3600) 00

190

UIM 1,, Standard exterior lighting installation. (IIIL-L-6730)

WADCG TR 55-1743

trained pilot to the extent thit he will spin in a Link trainer (8). Ina recent night formation flight accident a sturviving pilot reported thathe "saw' the other two aircraft in the formation peel-off to the left when,actually, they had not changed course (16). On the basis cf this falseinformation he maneuvered his aircraft so as to co111%de with the other twowith a resultant loss of one pilot and three F-86D aircraft. The "peeling-off* of these two aircraft is typical of the nature of the autokineticillusion.

Investigations of the autokinetic illusion reveal that the apparentmovement is greatest and most frequent when small (point-source), dimlights are being viewed; but it is "still present in the case of large lightsources (6, 7) and, although to a lesser degree, when viewing patterns oflights (8). Therefore, the use of more or larger area reference lights information flight should cause a reduction in the autokinetic effect. Ithas been demonstrated that autokinetic movement was frequent and largewhen only one reference light was visible during formation flight, was muchreduced when two reference lights were visible, and reduced even more whenthree reference lights were visible (8).

In sumnary, it may be stated that the formation lights now used on AirForce fighter aircraft are inadequate, and, therefore, render nightformation flight hazardous. Consequently, increased effort in the redesignof exterior reference lighting is needed,

IV. PAST RESEARCH ON FORMATION LIGHTI;NG

In February, 19145, a conference was held at the Bureau of Medicine,WVahington, D. C.,for the purpose of discussing the possible causes of thegreat number of aircraft accidents which occur at night (15)o The externallighting on aircraft during formation flight was considered to be acontributing factor in many accidents. The Navy, therefore, initiated alarge proaram on external lighting on aircraft. Reports on the findings ofthis research program started appearing in 1945 and continued until 1949(1, 2, 39, 5, 11 12, 13)e Most of the Navy's previous research issummarized in a single report in which the recommendations for exteriorreference lighting can be found (3)e The Air Force also conducted researchon exterior formation lighting (9). Most of the data from these pastInvestigations were obtained by pilot ratings in flight test programs; andadditional data were obtained through laboratory research. The criteriawhich the pilots used in making their ratings were based on the adequacyof the lighting systems under investigation as an aid in maintainingorientation, that is, their usefulness as an indicator of the attitude anddistance of the lead aircraft under various flight condiLions, e.g&, Joinup and formation flight on dark, overcast nights; moonlit nights; inovercast; etco Also, the comfort and fatihue associated with the use ofthe various lighting systems were considered. A summary of the findingswith respect to the variables studied is presented below.

WADC TH 55-124 4

SUMARY OF PFOUSL P3BEABCH

(1) Number- ofreference i,.htn: With only one point-source referencelight visible, the attitude of the lead aircrafI ' not di-srornable on darknights; distance estimates are difficult; .nd autokinesis is severe.Therefore, a single point-source reference light was rated as beingdefinitely undesirable. When two lights are visible, autokinesis is reduced,and aircraft attitude and distance estimates are improdyd providing thatthe two lights are strategically located. With three or more referencelights autokinesis is further reduced, and estimates of the aircraftattitude and distance are definitely improved if the three lights arestrategically located. -

(2) Location of the-reference lights: The wing pilot desires to seethe same detail of the lead aircraft that he sees in daytime flight. Thewing position, juncture of the wing and fuselages the tail, the nose, andthe canopy give unambiguous information. The most satisfactory locationsfor formation reference lights are found to be (1) the tip or near the tipof the wing, (2) the fuselage near the juncture of the wing, and (3) thetail section of the aircraft* If these locations are used, thrmesimultaneously visible reference lights appear to be the minimum numberwhich will provide adequate information about the attitude and distance ofthe lead aircraft*

(3) C 2olo of referege -lightus Traditionally, the starboard winglight has been green and the port wing light has been red, Color codinghas merit in that it assists in making the aircraft's heading apparentduring rendezvous and join-up. However, since no systematic studies wereconducted in which color was varied, little can be stated about this factoreFor purposes of maintaining dark adaptation, red is preferred* However,during formation flight, because of the low intensitites involyed and thesmall visual anples subtonded by the reference lights, the effects of coloron dark adaptation are of little importance.

(4&) T~ZRe of USIAhtIn:

a. Pint -sourges Point sources of light (filament bulbs withtransparen% covers) frequently present ambiguous cues for spatialorientation. Distance estimates of point sources of light aredifficult, and reversals of apparent position occur, i*e*,confusion as to which light stands for what section of the aircraftmay occur. Even when many point sources of light are used,ambiguity may result under some conditions.

b. Flood-ligiting Flood lighting the aircraft surfaces is anexcel'Ient method of providing orientation cues. This method ofreference lighting provides excellent cues for join-up and forformation flight, even through overcast. The types of floodlighting intastigated include flood illumination of the vertical

WADC TR 55-14 5

SUMARY OF FREVIOUS RESEARCH

(1) Number of reference lights: With only one point-source rcfhrencelight visible, the attitude of the lead aircraft is not discernable on darknights; distance estimates are difficult; and AuivkJ nesi^ i: scvere.Therefore, a siugle point-source referance light was rated as beingdefinitely undesirable. When two lights are visible, autokinesis is reduced,and aircraft attitude and distance estimates are jmvroved providing thatthe two lights are strategically located. With thrtt or more referencelights autokinesis is further reduced, and estimates of the aircraftattitude and distance are definitely improved if the three lights arestrategically located.

(2) Location of the reference lights, The wing pilot desires to seethe same detail of the lead aircraft that he sees in daytime flight. Thewing position, juncture of the wing and fuselage, the tail, the nose, andthe canopy give unambiguous information. The most satisfactory locationsfor formation reference lights are found to be (1) the tip or near the tipof the wing, (2) the fuselage near the juncture of the wing, and (3) thetail section of the aircraft. If these locations are used, threesimultaneously visible reference lights appear to be the minimum numberwhich will provide adequate information about the attitude and distance ofthe lead aircraft.

M() Color of reference lightsl Traditionally, the starboard winglight has been green and the port wing light has been red. Color codinghas merit in that it assists in making the aircraft's heading apparentduring rendezvous and join-up. However, since no systematic studies wereconducted in which color was varied, little can be stated about this factor.For purposes of maintaining dark adaptation, red is preferred. However*during formation flight, because of the low intensitites involyed and thesmall visual angles subtonded by the reference lights, the effects of coloron dark adaptation are of little importance.

(4) Tho of- lightinA:

a, Point sources, Point sources of light (filament bulbs withtransparenz covers) frequently present ambiguous cues for spatialorientation. Distance estimates of point sources of light aredifficult, and reversals of apparent position occur, i.e.,confusion as to which light stands for what section of the aircraftmay occur. Even when many point sources of light are used,ambiguity may result under come conditions.

b. Flood light&nM: Flood lighting the aircraft surfaces is anexcellent method of providing orientation cues. This method ofreference lighting provides excellent cues for join-up and forformation flight, even through overcast. The types of floodlighting investigated include flood illumination of the vertical

WADC TR 55-14 5

stabilizer, of the horizontal stabilizer, of the fuselage, andof the wing surfaces. Flood illumination of the verticalstabilizer was particularly liked by the test pilots. Theinstallation of the light sources and the control of the lightdistribution produce many ;jroblems. Also, the weight andelectrical demands of such lighting itior-a are muchgreater than those of the present lighting systems@

a. Linear lightst Linear li~hts give relatively unambiguousinformation. The solid surface appearauce of extended lightsources provides good distance and attitudo cues. In this respect,these lights are superior to those which are point sources*Linear lighting systems are enthusiastically supported byexperienced pilots who have observed them.

(5) Bihtness of reference lightst During mos; night formation flightthere is sufficient ambient illumination to see the silhouetted contours ofthe lead aircraft. In fact, on many moonlit nights the use of formationlights is not even necessary. In acme cases the exhaust flame providesenough light to be of assistance. On moonless nights or under overcast#however, there is not sufficient ambient light for safe formation flightunless formation reference lighting is provided. The intensity of formationlights should be quite lowv Pilots report that above certain minimumintensities the formation lights produce a glare, and the dim silhouette ofthe lead aircraft is no longer visible. Hence, important orientation cuesare lost. The specific intensities and the control of these intensities forthe various formation lights are shown page 11.

(6) Flashinu versus steady lights: Steady lights are definitelypreferred to flashing lights during formation flight. It was believedearlier that flashing lights were desirable because they reduce theautokinetic illusion, but later studies and test flights resulted in adefinite preference for steady lights during formation flight*

On the basis of the past research on formation lights and interviewswith operational fighter pilots and lighting engineers, several soundrecaumendations on the design of formation lights can be made. Thesereccmmendations are given in the following section.

V. ECailENDED FOPMATION LIGHTING SYSTEM

The recomendations that follow are largely based on the previousresearch discussed above. However, comprcomises were made in order toutilize the standard eross-countiy navigation lights now in use on fighteraireraft. As mentioned previously, the recomnendations are general innature in order that they can be applied to a wide variety of fighteraircraft.

WAXC T 55-124 6

(1) Location of formation lights, A minimum of three simultaneouslyvisible reference lights are recom ended. These reference lights should belocated near; (a) the juncture of the aircraft wing and the fuselage, (b)the wing tip, and (c) the trailing edge of the tail surfaces. Theselights should be located so that at least threa are visible for anyanticipated flight pattern*

(2) TYves of Formation Lights:

a. Wing-tky light' The wing-tip lightm in current use on AirForce fighter aircraft mre visible to wing aircraft pilots onlybecause of scattered light from the plastic lamp cover., When thewing navigation lights are dimmed for formation flight, theyprovide a minimum of .001 candles in the direction of the wingaircraft (from 1100 to 1700 as specified in NML-L-6503A)o Thisintensity is minimally adequate for close formation flight. Thereare two objections to this type of wing-tip lighting for formationflight. One objection is that this light appears as a 'point*source, though it should be noted that flight personnel do notconsider this objection to be serious. The disadvantages of pointsource lighting were discussed above. The second objectionconcerns military security during formation flight* When in thedimmed position the wing-tip navigation lights emit approximately0*4 candles over a fairly large area in front of the aircraft.These lights are visible from positions in front of the aircraftfor a distance of over three miles under conditions of goodvisibility (4, 10). If these lights do not provide the securityrequired by fighter aircraft, particularly for low altitudetactical fighter missions, a redesign will be required*

Two recommended modifications of the wing-tip referencelightint that would satisfy the requirements stated above are asfollows:

1. The present wing-tip lights can be slightly modified sothat they will provide sufficient formation reference lightingwith a minimum emission of light forward of the aircraft* The

present transparent cover of the wing-tip light extends from00 to 1100. This is shown in Figure 2, It is reccomnendedthat this cover be extended to 1300 or 1400. The cover portionfrom 1100 to 1300 or 1400 should be a diffusing medium such assandblasted plastic. The diffusing cover would provide agreater proportion of light in the direction of the wingaircraft, Therefore, during formation flight this fixture,even with a considerably reduced candle power output of thelamp, would provide sufficient light for the wing aircraft.Thus, less light will be emitted forward of the aircrafte Also,this fixture would appear more as an extended illuminatedsurface than as a point source of light.

WO V 55-124 7

Standard wing-tip fixture

SLinear wing-tip formation light

Modified (1400) wing-tip fixtureI , i• 110°

Transparent cover

Diffusion cover

Area of diffused light

I I

Ll 0 iA

FICURE 2. Recomended alternative methods for wing-tip formation lighting.

WADC TR 55-124 8

2. A second recommended solution is to provide a linearwing-tip trailing edge light. This reference light shouldhave a minimum length of about five inches and minimumeffective width of approximately 1/4 inches. Severalshorter linear lights can be used in place of a single fiveinch fixture. Engineering installation of +his type offixture has been made for low performance aircraft (2).The use of the wing-tip trailing edge linear light isparticularly reccmnended for uLne on those aircraft on whichthe thin wing construction does not t r=it installation ofthe wing-tip navigation light. See Figure 2 for anillustration of the principle of linear trailing edgereference lighting.

b. Fuselaae linear-lightas Flush mounted linear lights shouldbe located at a distance of approximately one foot aft of thejuncture of the wing and fuselage. (In some aircraft this distanceshould be increased so that the swept back wings or the tip tankswill not obscure the lighting fixture. On delta wing aircraft itmay be necessary to have two such fixtures on each side of thefuselage, i.e., one above and one below he wing, in order that onewill always be visible.) These fixtures should be about six toeight inches in length and about 1/2 to 1 inch in width. Thefixture should be mounted parallel to the longitudinal axis of theaircraft and at about the same level as the wing root. The glassor plastic flush mounted cover whould be sandblasted so that theemitted light is diffused. The general appearance of such afixture is shown in Figure 3o See BuAir Drawing 203-0 for details.concerning a similar fixture used on the Navy F3-3 aircraft*

c. Tail Formation lihtse The type of tail reference formationlights specified in Mi1-L-6503A is satisfactory. The brightnessesand control of brightnesses of the tail reference lights, however,have been modified in the recomendations that appear below.

Floodlighting of the vertical stabilizer is recommended fortraining aircraft in which night formation fliiht is conducted byrelatively inexperienced pilots. The frequency of night trainingaccidents is sufficiently high to justify the application of thismethod of formation lightin8 to training aircraft. Previousreports on external flood lighting should be consulted (9, 11).Strips of reflective and diffusing material, such as paintedemblems, placed on the vertical stabilizer will increase theeffectiveness of the floodlighting.

do Section fusele lightas The 'turtlebaokw fuselage lights,specified in Nil-L-6503A are satisfactory. The brightnesses andthe control of these brightneases are discussed below.

(3) Brightness of forMAtion liRhts: The brightnesses of formationlights and the control of these brightnesses are sutmarized in Table I below.

VADC TR 55-124j

Taillights

Fuselagesection lights

Fuselage Diffusing cover (140o) lightlinear lights

• I Recormended exterior lighting arrangement.

FORM FORMHEDIU• BRIGMT

DIM UP

TIOMM Recczuuended exterior lighting control knob.

WADC TR 55.24

- .10

:h44 >0 > I IL) >D4>

P4a *I -4dal 0 C0 000 Mi 00 4) 4)D P0 (D0 * W04

a) 0 0 4J 0 40> 00)0

.44- 0 p~~~44 9.4 A N)i0.3g

>b >b "i >. C; U@ 44 4a%-0or 04r C4~ O W1P0( 4: 04 44) 0In1

.42 4)4 0044 0 0) 0 0 .0 0 0441 L 4~ 41 0* o.41r40 0~ 14 20.0

*4 Y.Iu- tOC 4$

00 -4 0 ) 03

1 ~ ~ ~ 43434O

.0 4

X >b 4.3'r4 @44

A~~4 0 0.14ce 44

go CD 4) 004 4.1P445 4-P 41 4 10I StO M2 44 0 0 040 qa 4

4) '4 0 4-b1 1

04 A 4lAi

WADC~ R 5512 1

GJ,) 'DIu.. ol Lion lo.ý11 .- s 'i:tro rcforoaco lig'ts on the starboardwing tip should be green; the reference lights on the port wing tip shouldbe red; the section lights should be white; and the tail lights should bewhite and amber to comply with Mil-t-6503A. The fuselage linear lightsS should be amber*

(5) Control of exterior reference lights, The recommnnued design ofthe control for the exterior lights is shown in Figure 4. Vhe control knobshould be designed so that a stop prohibits turning the knob past the *off"position when turned counterclockwise, and Another stop prohibits turningthe knob past the Ocruise" position when rotated clockwieir, The advantagesof this type of control ares

a. A single control is used to select six conditions of externallighting, thus simplifying the pilot's task. These six lightingconditions are Dim, Medium, and Bright Formation, Soin Up, Cruise, andOffs

be The control is designed so that its position can be determinedtactually by the pilot and, therefore, does not require visualmonitoring.

a. The three settings of the formation lights provide for a widerange of flight oonditions, The *Bright* setting provides adequatereference lighting for formation flight and also maintains the wingtip navigation lights at the cruise intensity* This provides for crosscountry formation flight where it is desired that other aircraft bealerted. The VMediumw setting is designed for standard conditionsduring formation flight, The "Dim* setting is designed to providemilitary security during formation flight. Also, the VDim" positionis desirable for formation flight on very dark nights when glare ofbrighter lighting would make invisible the dim silhouette of the leadaircraft.

VI. DISCUSSION

The scope of this report is limited to the external lighting used onfighter aircraft in formation flight. No attempt was made to investigate oralter the design of the navigation lights which has been determined byconvention and international agreement. In an effort to minimize theccuplexity of the external lighting systems on fighter aircraft the

Conventional navigation lighting system components are utilized for formationreference lighting• Therefore, the formation lighting system recommendedin this report requires relatively few modifications of the present externallighting systems, The modifications reccmmended area

WADC TR 55-124

(1)1 Redesign of the wing tip navigation lights so that tc ar

visible to wing aircraft without violating military security. If this isnot feasible for particular aircraft an additional l-near wing tiptrailing edge lighting fixture should be installed.

(2) The installation of a linear light ott t•hq fuselag.._ near thewing root.

(3) A single rotary detent control knob to control the external lighting*This control provides three brightness positions for vrnmation lighting aswell as cruise, join up, and an off position.

(4) In training aircraft in which night formation flight is conductedby relatively inexperienced pilots, flood lighting of the verticalstabilizer is recommendede This type of formation lighting providesexcellent cues for join-up and for formation flight.

The intensities recommended for exterior lights are shown in Table 1.These intensities should be tested in a flight test program before they arefinally accepted as Air Force Specifications.

VII. SUMMWRY

This report has dealt with the design of external lighting for use information flight at night in fighter aircraft. The recommendations madeare based primarily on previous research on formation lights and on interviewswith operational all-weather fighter pilots and lighting engineers. Thestandard navigation light system was incorporated into the formation lightsystem in order to minimize the complexity and number of modifications required.It is believed that the recommendations contained in this report will overcomethe major objections to the formation lighting systems presently used eafighter aircraft*

WAX TR 55-124 13

1. Blasdels I*, Study of exterior lighting for Navy aiLrplanes. Fieldobservation by Composite Squadron Four. NAES Topical Report XG-T-119,TED No. 31333t May, 1945.

2. Blaadel, I. C. and Lazog So Study of exterior lighting for Navyairplanes.o Report No- 5. The instadllstion of lights on the trailingedge of wings for low level illumina~tion of nlz craft. NAMS Ra'portTED No. NAM 31333, No. 59 May, 1949.

3.Basadel, I, C. and Lazo, 3. StudX of exterior lightipS for Navalairplanes., Report No. 6. Night flight teats of experimentalexterior lighting systems on military aircraft. NAMS Report TMDNo. NAm 31333, No. 6, 3uneq 1949.

4. Bouma, P. 3. I~luination and black-outs. Phillips Tech. Raev, 1939,4, 33-19.

.5. Bromoe,, 3. and Orlansky, 3. P~reliminary re~ort on investIgation ofexterior 1ightina eciuituent. NAMS Report TMD No* RAM.313,33,Auagust* 1945o

6. Idwards, We 3vo and three-dimensional autokinetic movement as a&Dt~-fsz adbihns of stimuli-* 3. expe Psychol, 1954,,48, 391-398o

7. Edwarde, We Aut-okinetic movements of very large-stimuli., 3. UpsPaychol., 1954, 48# 493-495.

8. Oraybiel, A. and Clark, B. The autokinetic illusion-and Ai.m~1igatanoe in Aight-flyIng. Project No. X-148 (Ai-43 ReportNo. 3, Naval School at Aviation Medicine, Ponsacola, Florida,February, l94~5*

9. Ora".e, 0. naineeriw-azuI develotunent test-of eXterior_ lihtIn.&re_~ee'a Project Noe 3-46-.5p The Air Proving Ground CcmmandeEglin Field, Florida, May, 1947.

10. Knoll, He A., Tousey, e., and Hulbert, I* 0. Visual thresholds oateadfv Dolpt soures of light In fields af brightnesses frau dark-todg~iah1.o 3* opts Soc* Amer., 1946o 369 480-482.

Ile, Orlanaky, 3. Report of-eXterior l±ighting for Navy airplanesa ReportNo. 2. The use of floodlights for the exterior lighting of navalaircraft, NAM Report TMD No* NAM 31333, No. 2, June, 1946.

WAXO TR 55-124 14

12. Orlsnsky, J. Study-of exterior liphting for Navy airplanes. ReportNo. 3. Flight tests of some exterior lighting systems to facilitaterendezvous and formation flying of naval aircraft at night. NAESReport TED No. NAM 313333. No. 3, July, 19i46.

13. Wagner, H. G., Blasdel, I. C., and Lazo, 3. Study of ext~eiorlighting for_ Navy airplanes. Report No. 4o. A method of exterioraircraft illumination using transpnrent acrylic plastic. NAES ReportTED) No. NAM 31333, No. 4t, February, 1949.

14. Walker, go L. gyestigation of visual factors contributin. to nightaircraft agcidents witb sapecial reference to methods of lightingp e BuVed Project X-498 (AvO265-P) Report No. 2, Corpus Christi,October, 1945.

.5. Minutes o pconference on the external lighting of aircraft anddisorientation durinR nighl flying. Conference at BuMed, NavyDepartment, 14 and 15 February 1945.

16. Beport of special investigation of major aircraft accident Invo•lnthree F-86D aircraft. Office of the Inspector General, Norton AirForce Base, California, 29 December 1954.

WADC TR 55-124 15