NADC-77-107-30

• -J

SLIFT SYSTEM INDUCED AERODYNAMICS OF•:, V/STOL AIRCRAFT IN A MOVING DECK ENVIRONMENT

o VOLUME I TECHNICAL DISCUSSION

McDonnell Aircraft Company iMcDonnell Douglas CorporationP.O. Box 516 - "-:St. Louis MO. 63166

C) 29 September 1978

C-2

9Final Report for Period 30 September 1977- 29 September 1978

Approved for Public Release Distribution Unlimited

Prepared forNAVAL AIR DEVELOPMENT CENTER Q 1 0 i -'WARMINSTER, PENNSYLVANIA 18974 ~ 1

,fCUAI1••".tAS4FICATION OF THIS PAGE (11?,n Ole Enf-rd•d

READ) INSTRU'CTIONS/REPORT DOCUMENTATION PAGE _________T_______, __" • ~~IIt:i,'RE. COMJ'[.I.:1IN(; I. 'HMI ... I4-- !

1. REPOR Ur - 2 GOVT ACCt ION NO. 3 RECIPIENTS ZAT'.L06. N4.jMILFR

NAN.DC _.7-lO7-3t) 30...._- -- _--_-

Lift System Induced Aerodynamics of V/STOL . __ Final Technical X(epvrt,'" " , \ .i: O.l l F'r1. a'.' i ,' ,:r 7l . ,ol 1 1..

Vo1 L1111 1, Techn icai D~isc uss ion. N/A -

- .AuTpO ..... _. --. a...LQ*-TRACT O0 GI4tA, NT N ;MaE ',

James H. Kamman " / N62269-77-C-O'365Charles L. /all1 -. .

9 PERFORAING ORGAF4IZATION N AME ANU AOD RESS - 0 PR -I _AM ELEMEN_ T P__ OJEZT. TAKI AqEA A WORK U*. I NuI$8ERS

McDonnell Aircraft CompanyP.O. Box 516St. Louis, Missouri 63166

i -ONTROLLING OFF'ICE NAAME ANO A0ORESS 12z. -R,--,RT QAT

Naval Air Development Center . ' _ -ba r 78Warminster, Pennsylvania 1897-4 '.. , ' ... AIo•op..oe.

14 MOiT' • N- AI1-, CY NAI.4E & A DRFI SS,-f dlfle'ý ' 'S C ,(''it,.A OSft ,r :EC-- ITV CLASS '#i( •, -r .

"inclassif ied

Unlimited

Unlimited

'9 5'-PPiMENTARý %D)TES

V/STOLGround EffectsSuckdownFountain ForcesShip Motion Effects

";lhe propuIlsive lift system i ndu ced aerodviiam iccs o f mu tIi- iL -iV"s ; l--craft configurations were experinentally evailuated over a roe,,,ini, deck vwe atsLatic hover conditions. Several model configurations re!res;ent;,!.ive of .id-vanced subsonic and supersoni- V/STOI. aircraft wore tesred.

Dynamic jet-inloced force and moment data were obtia ied 'or lw ovinr,, pit, ,'-ing, and rolling motions of a simulated seaborne ]indlin. platfoun ev .- ra.:,--r

DD :, -I. ' 1

rFr

"-1SECURI'Y CLASSIFICATION OF THiS PAGErWPan Dome Enrer.d)

20. (Cont'd)tof heights, amplitudes, and frequencies. Configuration effects were assessedat both static hover and deck motion conditions, including the effects of wingheight, fuselage contouring, lift improvement devices, and nozzle arrangement.In addition, tests were performed to separate the effects of deck motion on thefountain impingement forces. Empirical procedures were defined to aid in pre-dicting the dynamic jet-induced forces and moment variations with deck motion.

Configuration design and model testing guidelines for V/STOL aircraft aredescribed. Recommendations are also made for further research to provide addi-tional informaLion required to develop generalized prediction procedures.

i

I4t

.*' :

CLASFCTOid .c" 25(~, .. F~

.IFOR"WORD

An investigation was conducted for the Naval Air Developmrc1nt Center

(NAI)C) by McOonnell Aircraft Company (MCAIR) to :is!e.•s the propulsivc lift

system induced aerodynamics of V/STOI aircraft over a mov ing deck. The stidI

wis performed under Navy contract N62269-77-C-0365 with Mr. M. Fl. Walters

of NADC as contract monitor. The MCAIR efforts in this program were accorm-

plished under the direction of Mr. J. H. Kamman with Mr. C. L. Hall as

principal investigator, both of the MCAIR Propulsion Department.

The authors are particularly indebted to Mr. J. 1). Flood for his effort

iivolv;d in the test program preparations and to Mr. K. P. Connolly for his Iassistance during the data reduction and report preiv ratinn. Sp•.ci

acknowledgements are due Mr. H. Sams, Dr. E. 1). Spong, and Mr. R. !1. Owen

for their contributions. IThis report consists of two volumes. The test progrir. descrip ion, 2: t-

annivses results, conclusions and recommendations are presented in Volume 1.

Appendix A, Test Run Summ-ary, Appendix B, Static Induced Aerodynamic Data,

and Appendix C, Induced Aerodynamic Data in Time and Freqaencv Domains are

,given in Volume II.

" IIII

TABLE O1 CONTENTS

SECTF ION PAGL

1. IN T RO&M)DU .: .O.. . .......

2. MODELS A.ND VESI F\ACLl. IIY . .......... . .

2.1 Subsonic V/SICI, Models . . . . . . . . . . . . . . . .S Supersonic V/STOa. Model . . . . . . . . . . . . . . . .

2.3 Model Instrumentation . . . . . . . . . . . . . . . . . 12

Test Facilities . . . . . . . . . . . . . . 2.

3. TEST PROGRAM ...................... ........................ 34

3.1 rest Variables ............. .................... '.3-

3.2 Test Procedure.......... . ...................... 411

DATA REDUCTION AND REPEATABILITY. ......... .............. 4.

4.1 Static llover Data Reduction ...... .................

4.2 Dynamic Data Reduction ................ 454.3 Data Repeatability . . . . . . . . . . . . . . . . . . 4

5. DISCUSSION OF RESULTS ..................................... 50

5.1 Static Hover i)ata .............. ................... ... ij

5.1.1 Subsonic V/STOL Configuration ......... 51

:. 1.2 Supersonic V/SJ'DL Configuration ........

5.2 Dyn.,:mic Deck Motion !.FcI ...t....s .................... 88

5.2.1 Dynamic Jet-Induced Force and Moment Data . . . 005.2.2 Frequency Content and Phase Relationships of

tihe Dynamic Data .......... ................ 118

5.3 Empirical Prediction Procedures ........ ............ 1310

5.3.1 Prediction of Deck Motion Effects from StaticHover Data ................ ................... 1 1-.

5.3.2 Predict on Procedures for Three let SubsonicConfiguration . . . . . . . . . . . . . . . . . I

5.3.3 Suggested Approach to the Development of

Improved Prediction Procedures .... ........ . 166.

6. CONCLUSIONS AND RECO>.!.ENb)AIONS ........... .............. 1I7

6.1 Conclusions .................... ...................... j70

6.2 Recom. endat ions . . .....................................

TABLE OF CONTENTS (Continued)

Sect ion

7. REFERENCES ...................... .............................. 7

VOLUME I I

APPENDIX A - TEST RtU'N Sti't\lRY.. . ............. .................. .. A-1

APPENDIX B - INDUCED AERODYNAMIC DATA AT STATIC HOVER CONDITIONS . B-1

APPENDIX C - INDUCED AERODYNAMIC DATA IN TIME AND FREQUENCY DOMAINSFOR DYNAMIC DECK MOTION CONDITIONS .... ........... .. C-i

vi

- -- --- ----

1.81 S :l I 1.1.'1 LtAL IONS

i.1~fOU' N-o

2-I Suibson ic V '8 1. lii llv Cont oured 3-1) M1odel . . . . . . . 4

2-2 Subsonic V/STOL 2-D ['lantform Modul ......... .......... 5

2-3 Advanced Subson ic V/TOI n io Con) iuratio ........ 6

2-4 Snbsonic V/STOT. Model Detail limensions ........ 7

2-5 Subsonic V/SlOT. Semi-Contoured Planform Model ... ..... 8

2-6 Subsonic V.STI1. 3-1) Mode] iLh1 Uds and Pods Inst a lIed. 9

2-; Subsonic V/SIMO. 3-1) Model T with Complex Nozzles . . .. 10

2-8 Subsonic V/STO. 3-Jet Inner Re;jion Plate t i

2-9 Advancod Supersonic VNSTOI. Design,; .......... 13

2-10 Supersonic V/STOI odel Configurations .. ........ .. 15

2-11 Supersonic V/S1ll. :.Models ......... ................ 16

2-12 Supersonic V/STOL Model Detail Dimensions ......... .. 20

2-Ij V'SIl' .hdel Facilitv Instrumentation ........... .. 21

2-14 Model Balance .............. ..................... 22

2-15 V\/STOL Jet Interaction Test Apparatus ...... ......... 24

2-16 Propulsion Subsystem Test Facility ......... .......... 25

2-17 Centrol Console for Exhaust Flo:ws in the JITA ..... .. 26

2-18 Data Acquisition Console in the PSTF .. ......... .. 27

2-19 On-Line OscilL'eraph Strip Chart Recorders ...... 29

2-20 Hewlett-Packard 5451B Fourier Transform Analyzer forDynamic Data Reduction ............... ................. 10

2-21 Deck Motion Test Apparatus ....... .............. .. 31

"2-22 Deck Motion Control Console ...... .............. .. 33

3-1 lesLt Variable:: ............... . ................. .. I

3-2 Subsonic V! ST0] MYo ICo (n fig i urit ion Variables..s ..... .... 36

vi:

LIST OF I LLSrRAT IONS (Cont inued)

Fig cNo. P~

3- 3 Supers•onic V./STOI, .Model (Configutl!ttion Varialble•., 3 . 7 ;

3-4 Conoiguration Summary . . ............... 38

3-5 Test Programn Summary. . . . . . . . . . . . . . . . . . 39

3-6 Ship Motion Predictions Based on Reference 2 ..... 40

3-7 Electronic Control System ..... ............... .. 42

3-8 Sample Deck 'Motion Output Waveforms... ........... .... 43

4-1 Model Natural Resonance Frequencies ............ ... 45

4-2 Dynamic Data Reduction Functions ........ ........... 47

4-3 Data Repeatability at Static Hover Conditions ..... .. 48

4-4 Dynamic Data Repeatability .............. 49

5-1 Subsonic V/STOL Static Height Effects ........... .. 52

5-2 3-D Subsonic V/STOL Static Pitch Effects ....... .. 54

5-3 3-D Subsonic V/STOL Static Roll Effects .......... .. 56

5-4 Effect of Deck Size ....... .................. .. 59

5-5 Subsonic V/STOL Contouring Effects ... .......... .. 60

3-6 Subscnic V/STOL With Lift Improvement Devices ..... .. 62

5-7 Subsonic V/STOL Roll Effects on Induced Lift with LID'sInstalled ............. ....................... .. 63

5-8 Subsonic V/STOL Roll Effects on Induced Rolling MomentWith LID's Installed .............. ................. 65

5-9 Subsonic V/STOL With Wing Pods .... ............ 67

5-10 Subsonic V/STOL Wing Height Effects ............ ... 69

5-11 Subsonic V/STOL Nozzle Arrangement Effects ...... .. 70

5-12 Subsonic V/STOL Complex Nozzle Effects .. ........ .. 71

5-13 Subsonic V/STOL Nozzle Pressure Ratio Effects ...... 72

viii

-

LIST O1' I .lI.STRAT IONS (Cont inied)

l i g1_11- No. No.'L• ."

5-14 Slubsonic V/STol. I hrust MiIas F"ffOcts .. . . . . . . . . 7"

5-15 3 Let Superson iC V/STO1. Static fteight If'ct 7....... 5

5-16 3 Jet Supersonic V/STOL StaL ic Pitch If fects... ..... ..... 76

5-17 3 Jet %upersonic V/STOL Static Roll Effects ...... ... 78

5-18 Supersonic V/STOI. Contouring Ef fects ......... 81

"5-19 3 Jet Supersonic V/STOI. Thrus;t Bi as Effects ... ...... 82

5-20 Supersonic V/STOL Number of Nozzles Effect .... ...... 8 1

5-21 Supersonic V/STOL With Lift Improvement Devices . ... 84.

5-22 Supersonic V/STOL Roll Effects on Induced Lift withLID's Installed ................. .................... 85

3-23 Supersonic V/STOL Ro.l Effects on Induced RollingMoment W'ith lID's Installed ......................... 86

-4 .iupersonic V!STOL ing Iigi~l,t Effects.... ........... S7

5-25 4 Jet Sumersonic \/SSIOL Stat lh;e ht Effects .... ..... A9 !

5-26 4 Jet Supersonic V/STOl0. Static Pitch Efffects ..... 90

5-27 4 Jet Supersonic V/STOL Static Roll Eftects ...... .. 92

5-28 2 J.et Supersonic V/STMI. Static 9ci,. Fff'ct• 9

5-29 2 Jet Supersonic V/STOL Thrust Bias Effects ...... .. 95

5-30 2 Jet Supersoni,- V/STOL Static Pitch Effects v.....96

5-31 2 Jet Supersonic V/STOIL. Static Roll Effects ...... .. 98

5-32 Tnduced Lift on Fully-Contoured Subsonic V/STOL ForHeaving Deck ............ ..................... 101

5-33 Induced Lift on InTier Region Plate For eaving Deck

Motion ........................ ........................ 1q3

5-34 Subsonic ViSTI1, Heave 1rcqluenc.v Vi fect t.s ..... ........ 1;)•

5-35 Subsonic V/SfOl hlea',e Amllit ide P ffeci ........ It..

t x

l. ST OF I 1IASTRAT IONS (Cont inuivd)

5- io Subsonic v I't&O. Indumced L1i t t Ia Ii ir: .b . . 106

5-37 Subsonic V/STOT. Induced Rolling Moment For Roll ingDeck . . . . . . . . . . . . . . . . . . . . . . . . . 107

5-38 Subsonic V/STOL Height Effects For Rolling Deck . . . 108

5-39 Subsonic V/STOL Induced Lift For Pitching Deck . . . . 110

5-40 Subsonic V/STOL Induced Pitching Moment For PitchingDeck ...................... ......................... ill

5-4i Subsonic V/STOL Height Effects For Pitching Deck 112

5-42 Subsonic V/STOL Induced Lift For Heaving and Rolling

Deck ...................... ......................... 14

5-43 Subsonic V/STOL Induced Lift For Heaving and Pitching

Deck .................. ......................... 115

5-44 Subsonic VI/STOL Induced Lift For Pitching and Rolling

Deck .................. ......................... 116

5-45 Subsonic V/SOL Induced Lift For Heaving, Pitchingand Rolliju, D-. k ............ ................... 117

5-46 Subsonc V/STOL. Induced Lift For Dvnam. icVertical Takeoff and landing Simulation .. ....... .. 119

5-47 Planform Configuration Effects For Heaving Deck 120

5-48 Subsonic V/STOL1 LID Effects For Heaving Deck ..... 121

5-49 Subsonic V/STOL Fusela.4e Contouriiig Effects For Heaving

Deck .................. ......................... 12?

5-50 Subsonic V/STOL Inducd i t. PSD Response to Heavins

Peck .................. ......................... 124

5-51 Subsonic V/STOL Indijuc,' Li-!L PSD Response with

Frequency Variations. ....... ................. ... 125

5-52 Subsonic V/STOL Tndoued Lift FSD Reýp rFe lith!g.Aplitude Variations ........ ................. .. 127

5-53 Response Phase gt '..With: Hoiiht Vairiitions ForHeaving Deck .............. ..................... .. 129

l~lsl OF l1±ll:SfPl~b llo•' ((:,;il iiu,.,-t)

" ur> ",,. laL•,c-

7-5-4 'Iel nt , PL.'50 ,\nxlt' 1ili S.ci ,Iht Var , AI 1.'1 1• r Poll i : n., c .. . . . . . . . . . . . . . . . . .. . . 1 31

)-5 1 AnpI i Lti.de, :rnd Phasoe Ani1.!t, :rcL-(! te PI', o:y-> t l' Il ,' in II

Dock . . . . . . . . . . . . . . . . . . . . . . . . . .. 32

5-56 Anp1 itude 'Ind Phase An qIca Froeq enc - Rv orp C t O .1 1 n11g

Deck . . . . . . . . . . . . . . . . . . . . . . . . . . 133

5-57 Subsonic '/s-rlot. Static To l)vna;:mic Data Cornparison Inae l0i:,,a in For Ijiavi g Deck . . ..

5-58 Subsonic v/!SiST. St atic to Dvri!::ic Datia Con'parison InPhysical Domain For Heavin Deck. c .......... ......... . 3711

5-59 Subson L \S'iTOL Stat i c fo l)vnai-.•., n Indu1: l.i2 "t DPat 1

Comparison For Pitching Deck ...... .............. 138

5-60 Stibsan ic V!STOL St-•tic &To Dvn.ar:ic ]n!iucCd PitlhiniMoment Data CoFopr r 1cr Pit,'tin :-- :)k,... . ............ 1 39

5-61 Subsonic V/SiOL Static To l)vnaii Indou:,-d '. i:t andInduced Rolting ".oment Comparison For Roflinig Deck . 140

5-62 Supersonic V/STOI. Static to Dynamic nrdux-ed !i.ft:c citnComparison For Heaving leck .... .............. 142

5-63 Supersonic V/STOL Static To Dynaric Induced L.i ft DataComparison For Pitching Deck .......... .............. 143

5-64 SuFersonic V/S0T1. Static To D'namic Ulandcc-d i'it:liinc

Moment Data (,r'.nrarisan For Pit -hin- ....... ........ 44

5-65 Supersonic V/STOL Static To Oyna;mic In:'uccd Li ft aindInduced Rolling Moment Comparison .-or RPlling Deck .. 145

5-66 Subsonic V/SIOT, Static To Dvnamic Indu,'Ld 1.i-t andInduced Rolling Moment Diata Coopar!soii ,o- lica:ine a ndRolling Deck .................... ...................... 1 6

5-67 Subsonic V/STOL Static To Dynamic Indu,'cd Lift DataComparison For Pitchinu and Ri* i: , .. ...... 148

5-68 Subsonic V/Sih Static To i)vnamiL c l.........a:{ ta Co.-.-parison For Pi tLhinIs r M ld Il inu ;t , P7 i'l!,sc . 1,9

5-69 Fourier Series; Fit of Induc L'd LiI : L:iirt is• i;or IHeaving Deck ................ ...................... 7.15

xl

1. 1s OF I0 1.1,ST1TRATI'ONS ( Cont in ed) I1VL•-,e No. iL_.

5-70 Fourier Series Ftit of Induced Litt Variations ForPitching Deck . . . . . . . . . . . . . . . . . . . . . . 153

5-71 Fourier Series Fit of Induced Pitching Moment Variations

for Pitching Deck . . . . . . . . . . . . . . . . . . . . 155

5-72 Fourier Series Fit of Induced Lift Variations ForRolling Deck ............... ....................... .. 157

5-73 Fourier Series Fit of Induced Rolling Moment VariationsFor Rolling Deck ............. .................... 159

5-74 Fourier Series lit of Induced Lift Variations For HeavingDeck at Various Frequencies ............ ............... 1hi

5-75 Induced Lift Variation For Heaving- Deck Based on InnerRegion Model ............... ....................... .. 167

5-76 Induced Lift Variation for Rolling Deck Based on InnerRegion Model ............... ....................... .. 168

xii

LI ST 0 All BIiV 1ATIONS, ACRONYMS, AND SY.MioL-S

AC\ utt (,o)rce I .t Ion it I I il Al 111n ti On

A Foun~ic ncerics cot-: ij i-ent of c-O.Sh iC I unci On for complc\ ptriotiictda ( aI

A lT tOal com-bitmed t .it area of. all nozzles

b tI: tg ,pani, ~incI-- or cm.

BI ['Jur icr serie> Coc iC ic jen Of0 sinoe functLion for coml l~ex perijodic

C flean aerodviiamic chord tength1, inches or cm.

cc CroSS Correla tiOn StIti-sLiCai function

C FAS Non-Jirnensionalized induced axial force coefficient based on7static gross thrust

CENS Non-dirnensiOnalized induced lift coefficient based on static,gross thrusL

CFY S Non-dimensional 17zed induced side force cocff.icielt. based or. static,-ross thruISL

CPIIS Na-ilnio~zdinduced pitching moment coefficient based onStatiC gross thrust

CR2.IS Nen-dimensionjilized induced rolling, Morlent COCefficie'-.t based Onstait~ic gross thrust

CSD Cross pow~er spectral density stdtistical function

CYMS Non-dimons jonalized induced y'awing :acment coetfficient based onstajt ic, crL'-s thrust

0 1 Exit diameter of each nozzle, inches or cm.

D. Ecal~val ent nozzle exit. diameter based oil tile total areas of allno10z zles, inches or cii

D e Nozzle reference dimension 4 .024 inches (10.221 cm)

Frequency, 11z

FA Induced axial fo.rce(-

I. G otal StaitiC gross thruISt Of theL n1ozzle eXhaLust ill)"'

/ Ttrts t Itias r~i t 1

['y II fl(Ik'CC d d L fo rco

Ii i"ude IC n1ozz10 hvic'I IL 3bO'Ve L le deck, or the (IistLail~c of thle nIozzle

L it 1)L I )CV2 in 1,.'e 0h Lett I LI' i Io L of theL mov ing duck, itcI neits or c!-

h Iltiv ilng imp~ip it I1(e ,inclies or cmi

liz 11crtz, CYCle-S ')Lr seCOnd

J ITA JeL Interact ion Test Appairatus

.1. midtwied lift focLcigo he airframe

!SModel c l

NPR Nozzle nreSSu-re ratio, Pt /Pamb

1) Ap ent rc ss are

LpiM IndnICed pitching momient, inlb or kg-cm

IS D Power Spuctral Density statistical function

i'Srr PropuLs ion Sub-sv.stenl~ Tes-t Facility

2ptj Nozzlo 2xliau--t total pressure, lb fin or kg/ni4

uc ciroil .PA ieli~Lt, inl-I h or kg-cmf

R Au~to correlatiOn' StatiSticZ1l. functionx

R Cross correlation statiStical function

YI Ilidu.-'e yain Iomenit, in-lb) or kg-cm

t l'ime, seconds

T Period of one cycle, seconds

Ty Novzl c totLal t empo r, LI. rc, ',

D~eck pi tch angle, degrees

D eck i1 angie, degreezi

Lai- L iF!(' , seconds

Phjasu ;lflg] e between piltch wid roil or other combined deck motions,1

x. iv

10 groindt Vf ffeet ,the propulsive lift syst em induced acrodynani cs

expeor ienced b y Vj'STo)l i rcra r.L -;an s in )Ii ificant Iv y egrade t he a i rcr a f t li ft

c,1p[;Ibi it L ts %. I I as t Ite st ah I i Lv arnd controlI. In addition, for Operations

at sea, t.Ie !;Ili[ met ion will CcIuse fll CtwIit ions in these Induced force and lf~

YO inlveStigaltC these effects, the induce-d aierodynamics; of multi-jet

V/sTOL. aircraft configugjrntio~ns were experimentally evaluated in the dynamic

environment of a moving dleck as well as at static hover conditions. A

variety of model configurations representative of advanced suibsoflLC and--

SUper.sc'nic V/SlT01 aircraft were tested in the 'MCAIR l'roptilsion f'ubsystem

'Yost Facility utilizing the Jet Interaction Test Apparatus and Deck Motionl

Simulator.

Dvnamlic effects were, assessed for heaving, pitching, andi rolling Tnotions

of the deock over a range of deck heights, amplitudecs, and frequencies.

Further, the dyna!-ic data were analyzed statist ica] 1l, to determine the fre-

quency content anti phlase re'lat ionships between the deck motions and the

aerodynamic responses. Several configuration effectS were -also asses-sed in

the test Program including the effects of wing height, fuselage contouring,

lift improvemeint de-vices, and noz~zlii arrangement. Empirical procedure., were

defined to aid in predicting thce dynamic jet-indticed forces and moments

resutlting fromn deck motion. In this effort, compairison3 weemade between

predictions; based on static hover data and the actual dynamic response data.

Significant results relating primari]Y LO the effects of deck motion are

s-umm~arizcd below:

"o The responses of the jet-induced IEurce and ruomeniL data to deck

motion are of ai coImplex perio1dic nature at tie same iindJ'or multi-

ples of tire deck motion freqotency.'

"o Thle force and moment variations predicted from s ta':ic hover diata

can differ significantly from thc actual dynamr.ic data particularly

for combined me Lions (e g. , hea1ve andIC rell

oS imulation of the model z3:A r~ rface contour ing; is important,

particuolarlyv inl the foirn ~ltaiii.oing o reg ior

o Tile induced I ifti res ul t iito; trm con L:1 ,.in imping,-emenit inc rasc's as

the dheck he-aves; tow-.ard tic- modu 2

The Infountai n LOpar t1,11,Y the largest impact onl the torce an

momgent vnriaio~ins withi deck MOLten1.

o For a con f iglira L ion wit I hi ghI suckdown in ground effect, a-! increase

in lift- loss occurs when the deck heaves away fI ero the mode l

L The deck Mot ion frequency has little effect on [he statistical

aero)dynari c response but can affect the instantaneous response

chirac teristics.

L Properly designed LID's can significantly enhance the induced

litL even at substantiatl deck roll angles.

CO(fiUration design and model testing guidelines for V/STOL aircraft

are described based upon the data obtained in this program. Recommendations

are also made for further research to extend the empirical data base and to

provide additional information required to develop generalized prediction

procedures.

J

x< v i

I NTROIM;CTI WN

Operation of V/STol. aircraft from ships, particurlarly frorm small

I L-Ai~i loll tyeship)s, t;rrc Ii- Cis DD 11963 c 1ino:; du-st roýc or U'-fit proii tems

L11.10 tO Lit S hij p Trotion aInd Lilte f 10,I OwI ied cond it lars in Olie Iarid ing a rea. 4.

Lf iui o Lire landinug are.r , Lire, lif t sv stem indure d no rodvnahicr eh'suLed7

by V/S"TiL airctr If L C,11. sign 1it jeanLIV detograide tire a iI-rera CL I i ft calijiairil i LV- aS-

Weil a S Lilt sLab lit V ýrt I~r L mllr I. The rit ion Of tire slri:r mid Lire wind cond i-

tLions cnose- 11bc timLions inl these inductred forces arid urIoire Ls , fur LiicV(iiij i-

cat.ý irg ';ST0, a ircra ft Lake-a f and re!-VrNoevoemt-rs

Tire major ity of e sisLinig induceod aerodynamic data are for Static hover

-conditions- and cannot be used to assess Lire effects of deck motion. There-

tare, [Ic Pounael Aircraft Conrpanvll (M.CAI R) conIdric tori anl tiiVe st ýioatlair rincer

contract to tire Naval Air Develop1jMent Center (NAi)L) to paramietrically evailu-

ate tire jet-induced aerodynamics of typical advanced V/STilL aircraft above a

!TroVting phi t fern as well as It statiic hover c'Ondi Lions. Thirs inives tLýigtion c'aý

pefrne wtou aeýdded. COII~~ introduced.r by wind

A parameitric test program was conducted in tire MCAIR Propulsion Subsy'stem

lest Fe i li LV ill Feb rrra rv-Lir re 1978, as tag both fLl% ii o ordadsimple

fl!at tiaLte p)1lant arm. Models represenltative of subsoiric arid supersonic V/STilLI

aircraft conrfigurations. Tire jet-induced forces and momrents acting Onltile

aiiam mo~dels were mesrd ii mi- o tj)ionsI suLCi I~as-C eo tilned itA;'e

Deck Motion le TL App[ara-tLIs Was used to) simu1,,late both simp1le one axis deck

and roll. Simple sinusoidal deck motions were used to represen~t tile Ship

Tests were performed over a ran[ge Of d,:ckN motionl amplitudes anld fre-

quencies, representing responses to mioderate to rough sea condition1s. COn.-Ifiguration variables included w.ing, height, nozzle spacing4 and arrangement,

and model surface contouring. Tire tests- Lirus pro-vide an extensive data lbaseL On jet-indireed aerodynamics both for Static hover conditions and for dvn~rric:

conditions With deck Motion.

Following tire test program, thre force and momnt'li data were arnalvzed to

aIssess flire ef fects of dock rol(t ion , to compare1-C tire dviramic aind St~tiC Ih1(ver 1

data, and tO evaluat]e, tire effects of tire- conifiguration vairiables. Statistical

%nl v , es wele Used to dte 2t'mi. the frequeLcy con tent .,t the dvnari ], r.s.iwnlsc

[ Anl I tlld Lte' ph.iao relo t£L1,!sh1ijS hetweenl tLhe deck i ioton alld the flie,15urc11

respoitse of ti1e MOde Is. Parametric data plots were gnecrated Lt) assist ill

tile prediCti,on of the Iet-induced force.i and liimen Ls IctLil, on typVilea V/STOU.pliulorm., } Lmpiic le L pprolches tlhe prediction of the dyvnmiia rmsponsc

to deck motion were a Iso defined. In addition, guidelines relat ing, to general

V/S'iOL aircraft design and model testing were derived from the test results.

Descript ions of the models and the test equipment as well a.; the test

p•rogram are provided in Sections 2 and 3. The data reduction procedures in-

volved in computing; the induced forces and moments are discussed in Section

4' for both staptic hover and dynamic deck motion conditions. The results are

presented in Section 5 and conclusions and recommendations in Section 6. In

Volume II, a summary of tile test runs is given in Appendix A and the basic

static and dvnamic induced force and moment data are p-esented in Appendices

B and C.

2-

17U

2. MO DLLS AND TEST [AC IL ITY

Siuat I scale modelIs repruselltatiVc of I hO th SUbS01liL and supersonic V/S'iOi.

A i f¾,It cont igurat ions were tested inl tILe Jet Ilterac~ L01 ilu IcSt ApparaILSt)s f

the iICA IR Propulsion Subsysturn 'rest Flci I i Ly. Thie modclIs, inst rilnnen La iOll,

Anld toest equipment used in thle measulrerneulii of the ic1L-iidticed forces and

POMCItS are describid below.

t. SUBISONIC V/,STOL. MODELS - Two subsonic \/S17TOJ. models wcrc test;ed, a' full y

ContLoured 3-1-) model (Configuration 1) and a 2-1) planform model. (Configuration

.)is shown in Figures 2-1 and 2-2. These models, approximate .v 5 scale,

havo identical planforms to simulate the same advanced full scale vehiclei]lSLusrated in Figure 2-3. Thle aircraft represented has a lift fan inl thc

:orward fuselage and two lift/cruise fanis mounted above tile wings. Detail

d~i;;1ons ions for the model are given in Figure 2-4..Thle fully contoured model, Configuration L, Canalso beS 10COnfigured as a

modified Plariform model with a contoured lower fuselage and wings, as shownA

in Figlure 2-5. This is accomplished by removing tile upper fuselage section

11n-d adding a simple planfonn extension to simulate thle aft fuselage and tail.

Thle hor izontal tail is raised to SiMUlare a high tail. Lift improvement

iovicus (LID's) can be mounted on Configuration 1 consisting of two longi-

tudinal strakes and a lateral fence which are designed to increase Lthe lift in '

gr- cund effect by trapping thle fountain upwash. t-.:ing po0ds can be installed onl

,.1c w;ing to simlulate stores. Thle LID's and pods are illustrated in Figure

2-6. Thle model, as tested, has simple circular nozzles as shown in Figure

2-1. Yaw vanes can be provided in thle rear nozzles and both pitch and yaw

vanes in thle front nozzle as shown in Figure 2-7.

The 2-D planform subsonic V/STOL model, Configuration 2, was designed

inl a modular fashion to allow a wide range of parametric testing. W~ithi this

..lodel, the wings can be mounted in low, mid, and high positions. flh 2-1)

planform tail can be mounted in eithier a low or raised position.

An inner region plate model was tested to a limited extent to &eparate

the forces acting on the Center fuselage region from tile total airframe

forcc. 'This model, shown in Figure 2-8, consists of a simple flat plate

comprising the area bounded by the three nozzles.

2 .2 SUPERSONIC V/STOL MODEL - The supersonic V/STOL aircraft model, Config-

uration 3, is a 2-D planform model based on a configlurationi that has either

OneC Or two lift fans in the center fuselage and( eit-her one or tWJ lift/cruise

jets in thle rear, as illustrated b)% tile advanced dsn silotii ill Figure 2-9.

-LJ

u.J

LU(

-ILL

. . . .. . . ..... ....

(5

NNC

Cz 0

IdI

44.0 ft

51.9 ft

FIGURE 2-3ADVANCED SUBSONIC V'/STIOL CONFIGURATION

Ll1

Parameter Subsonic VISTOL

Reference Diameter, DRet 4.024 in. (10.221 cm)

Wing Planform Area, Sw 84.5 in. 2 (545.4 cm 2

Wing Span, b 21.66 in. (55.02 cm)

Wing Mean AerodynamicChord, c 4.13 in. (10.48 cm)

Tail Area, ST 17.0 in. 2 (1031,6 cm 2 )

Aircraft PlanformArea, Sp 159.9 ,.2 (1031.6 cm 2 )

C.G. Location,Measured from NoseAlong Fuselage Centerline 12.89 in. (32.74 cm)

Overall Aircraft Length, L 25.52 in. (64.82 cm)

Note OimensionS qveni in rn,,u•. scale

2 Jet 3 Jet Configurations

Die = 3.285 in. Die = 4.024 in. I, 11, 12, 13, 14,(8.344 cm) (10.221 cm) 2, 21, 22, 23

Aircraft C.G. Location 14.56 in. 2.323 in. 1.D.

Balance (36.98 cm) (5.900 cm)

2.323 in. I.D.(5.900 cm)

7.42 in. 21.66 in.

3.24 in.| (18.85cm) (55.02cm)

(8.23 cm) -.10.06 in.

125.55 cm)12.89 in.

(32.74 cm)25.52 in. (64.82 cm)

(a) Subsonic V/STOL

GP78 089S 7'FIGURE 2-4

SUBSONIC V/STOL MODEL DETAIL DIMENSIONS

j]

ui

0

0L-2U, uW-

cq3

0 u.

E a

- ~ ui

C-3

-AIAI

MCI.4..

'12

- -.- 1

1�

1

I

F I1

I

I I*1

I

FIGURE 2.8SUBSONIC VSTOL 3�JET INNER REGION PLATE

A\s wit It thle p I an tform Subsonic pit)de I. , canl f i! ;itr a iont 3 was d e.s i goed 1in a mod ai Ia r

fashionl to allow testing with a1 variety at niozzle a'rrangIM4,ltiiS anld wing pus ,I-

t iOnI S, as, ShO1 I scejIematica it V it I F guru 2-H). All AiaL-I1iTIcnlL i!; provided to

sirulIatý con to uring On the Iowcu fusel;I ae. itmaj riK tsL ilICn

I i0aIan 3 wure cen(Idc te wI%/ithI a thLI roe noz e, L. i rraiigci:iu! IL Lii~iosLsL i 14 (of

:i i ngLo large dliameter nozzle located fin the center iUS-jo] ageL and two sinall

d ia~neter noz'zles located inl the ail Vit d. This no/.lAO a rranigementci is well ats

the othier arrangements and configurat.ions arcL -Sl~t'n fin Figure -11 Lu addi-

t ion to thle nominal arraIngement , thle madu (-,il Lie conf igured (1) with l~arge

diameter nozzles in both tile center antd aift f-_selage and (2) With two trans-

ver'se medium diameter nozzles ill thle Centeur and two small diaimeter iio,ýzls ill

the rear.* The lonlgitudinial spacing hetween the fore aild aft niozzlus is

variable for both of these alternate nozzle arran,;remunts. Vetail model

dimensions are provided in Figure 2-12

The wing height on Configuration 3 is adjuitable to simulatE low, mid,

and iiigh positions. LID's canl be installed oil thv Lnominlal thiree nozzle

arrangement. These LID's, Shown in Figure 2-1 I(e), consist of thle two lonigi-

tudinial strakes and a lateral funcei.

2 .3 flODEL INSTRUME~NTATION - The airframe models wtore supported, as illus-

trated in Fiounre2-13, by a six-componnent strain i,;ee, balance which provides

muasurements of the jet-induced forces act ing~ on the airframe. A Task iHark

XX11I 1.5 inch (3.81 cm) diameter force balance, shiot.n in Figure 2-14, Wa-s

used due to proven accuracy in previous tests and high frequency response

(> 1000 tiz). rhe balance was positioned to align thle axial force gage, which

has thle lowest force rating (100 ibf), With tile lift -ixis. This provides an

accurate measure of thle l'ft forces3 actitng on the airframe (accuracv Within

0.25 percent of the maximum rated lead).

Thle jet exhaust flows were simulated with high pressure air at a-mbient

tempera ture. The nozzles of each of L:14. models were ia011-feti iC So aIs not toý

transmit any thrust force to the force balance, thus increasing thle accuracy

of tile jet-induced force measurements. A radial clearan'[ce Llf 0.0_'O i!Ich

(0.05 Lm) and an active grounding detection SVstem Wic-> provided between thle

outside diameter of the nozzles and tile m-odel. L-acO nozzle wai; instrument~ed,

ats illu:;trated in Figure 21-13, to dete2rmine thle aIozlc71 pressure rat Ic , ',ct

thrust * aa.d mass flow rate. Tile thrust characteristics oi Oacl: I~ozzle were

determined in and out of ground effect in the 'ICAI i, Nezz he Thrust .Stand. No

59 9 ftall Single Lift Fan with Dual LiftfCru ile Jots

38b0it

b) Dual Lift Fan% with Dual Lift/Cruise Jets

FIGURE 2-9 OP'i.005$5 12]ADVANCED SUPERSONIC V/STOL DESIGNS

S•-•-•24.1 ftI38.0 ft

59.9 ft

(c) Dual Lift Fans Ot?-olfl-19

FIGURE 2-9 (Concluded)ADVANCED SUPERSONIC V/STOL DESIGNS

1.4

~=

Lft Cruise Jets- ConfigurationL-tt r~liS JetsLift Fdni

3 Suiicontoured

View ContouredLowerSurface

A 31 20D Clean, Low Wing33 Mid Wing

34 High Wingq

3.00 in.(7 62 cm)

Ll~s High1.LIDsin rF "•L Midj'g

S-in. .•

(2.54 cm) - - Lov,

Height Front View1.50 in-

(3.81 cm)"32 2-0 with loift Impro0ernent

Device (LID) Installed

111.94 cm)

9,8 in.1 24.89 cmt

Lift Cruise Jets

Mci Fsvd Lift FansM 1dF~vd4 Jet35 2 with Mid Fans

36 20 •vith Forward Fans

Lift Fan M'd Fwd J2 Jet :

"s L38 2-0 with Forward Fan

39 2-D with Mid Fini

Lift Fan

FIGURE 2-10

SUPERSONIC Vi'STOL MODEL CONFIGURATIONS ol,.,

U

0

C

C0

C'

0

C'

C0(.)

E

C'U

�0

C'

-J- w

0t-

'70wU��

C IC0

C-,

a'

0

0C0C-)

VU,

I,,

LLI

0

C _j

0.

W'

cr0 L u

0

V.>

cZ

Vim

00

-cr D 0AI C

4, - *1

I

Parameter Supersonic V/STOL j

Reference Diameter, DRef 4.024 In. 00.221 cm)

Wing Planform Area, Sw 130.9 in. (844.5 cm 2 ) IWing Span. b 22.76 in. (57 81 cm)

Wing Mean Aerodynamic

Chord, c 6.24 in. (15.85 cm)

Tail Area 'T 27.9 m11.2 (180.0 cm2 )

Aircraft PlantormArea, Sp 321.0 i.2 (2071.0 cm2

Overall Aircraft Length, L 35.58 in. (90.37 c-n)

Note Dimensions given in model scale

17.27 in. 0576 n I.D.C. G. (43.87 cm)- (1.463 cm)

3 Jet Balance,\- _____

Configurations 2.323 in.°D-

22.76 in.(57.81 cm)16.10Oin. I, - -- q l ... - - (s 8 •

(40,89 cm) -' • -T-' -] • -(4089cm) 23.69 in. " "- 4.61 in. Die = 2.462 in.

24.33 in. -(60.17 cm) (11.71 cm) (6.253 cm,

(61.80 cm)- -

35.58 in. (90.37 cm)

Balance M 17.27 in. (43.87 cm)

4Jet 1.642 in. I.D.. 0.576 in.. , t11.463 cmjConfigurations (4.171 cm) " I

35,36

4.61 in. (71.71 cm)

T- 3.00 in . Die 2.462 in.3,90 in. (7.62 cm) j • , (6.253 cm)

(9.91 cm') Fwd CG.

13. 10 in. (13.27 cm) (512 i.4cm

,-.- ---- 17.27 in. (43.87 cm)Mid 7 - 2 i

Balance 2.323 in. 1D. (5.900 cm)

2.323 in. I.D. (5.900 cm) - -.. __. n

Z~~st w.114.46 in.. (413cm

Configurations 3.00 in.

38,39 (7.62 cm) 'D---.-- -n

Fwd Di8=3424 in.13.10 in. (33.27 cm)-I 20.27 in, I C.G. (8.344cm)

(51.49 cm)"35.58 in. (90.37 cm) - j

GP7SI 08S9 76

FIGURE 2.12

SUPERSONIC V/STOL MODEL DETAIL DIMENSIONS

20

ILI

x C,

_C)

I-U

I-c

z>, 0

N- --

-U -- j4cr 0 I.-c2

0

LL2

E c.

73-

Rolling Moment Element Balance Outer Case ,-\ - Balancu Inner Cawe

Side Force Element Normal Forc; Element

Noirmal Force Element Side Force Element

Axial Force Clement

a) Task Mark XXII Balance Details

Nil N 2 Balance no' mal element -Model ax~id (draci) force

Si S2 Banlance sidea element - Model sidER force'

A Balance axial elemnpt modlel nniiii~di hillf

Balance roll element m roiel fdwinq momr,,t

N 2(R21

Si (R3)<Banc

RightWing R i

Force s are ShownActing on Model

LowerSurface

of Lf

Model wn

Normal (Model Axial Forcelý 1200 hbiSide (Model Side Force) 600 IbIAxial (Model Normal Force) 100 lbf

Note Arrowii ndicate posilvemoads Yw(oe el 50f-b

0 P780-095.4

b) Model Balance Installation

FIGURE 2-114MODEL BALANCE

22

substantial ground effects on the nozzle thrust were measured except at

heights substantially below typical gear heights.

2.4 TEST FACILITIES - The major elements ot the test aWringument were Lhe1

Jet Interaction Test Apparatus, the Data Acquisition/iedht Lion Systems, and

the Deck Hotion Test Apparatus.

Jet Interaction Test Apparatus - The MCAIR V/STOL Jet Interaction lest

Apparatus (JITA), Figure2-15, consists of a 19 inch (0.481) 1.1). Settling

chamber, two independent nozzle plenum chambers, a model support beam, and

interchangeable nozzles mounted on the plenums. The JITA is located in a

32 ft. (9.75m) long by 19 ft. (5.79m) wide by 24 it (7.-2m) high test cell,

as illustrated in F'gure 2-16. The large test cell eliminates In% wall

effects which might influence the jet-induced aercdynamics. The JITA controlt

console for the model exhaust flows is shouii in Figure 2-17.

Hig], pressure air can be supplied conILnuOuSIV IroM OU) psi; tank.s at

a rate up to 16 lb/sec to the settling cluamber for simulating cxhaust flows.

The air is heated to approximatelv 100°F. The sec tling charmber ha,, a conia!

spreader screen and two normal screens to provide uniform flo" conditions ,o

the two nozzle plenum chambers. Nozzle pressure ratios from 1.1 to 7.1) cain be

tested. The plenums are provided with independentl, controlled pressure

'al*ves to allow testing at differ.Irnt fronL and rear iozz !c pressure rit-i-c-.

This feature is particularly important for some V/STOL confi,.uratio:is which

utilize both lift fans and lift jets.

The force balance is attached to the support beam which is centrally

mounted off the settling chamber. The test models are attached to the force

balance, which locates them away from the blylnu:. (typ ically [on• w;,lih.

span), thus minimizing the potential effect of the plenum blockage ,n the

induced flowfield.

Data Acquisition/Reduction Systems - A six-coMponenvnt strain gi, :xi

was used to measure the steady state and transient jct-induced forces. i u

steady state data, including the nozzle e'xhaust pressures and temperaturus,

the ground plane position and attitude, and the balan-ce outpuLs, were recorded

at a rate of two samples per second with a Datum .odc] 12d lDiital Iata Ait-

sition System (DDAS) and are filtered with a 10 Hz filtutr. The I)IAS nrovids

signal conditioning, amplification, and excitation for Up1 to 41) ;lput. 'hdnaiw.-is.

The data acquisition console is shown in Figure 2-18. The J i),i t ijZe~d O..ta

23

>~

03

cc 'I

CI-.

Friee jet r---1i -- ~ 1Test Unt Ofc rar Mapping( .A .'-Air Blast

Test ~~~Unit -O'cAeaFr Unj I"De flectors

V STOL Jet ModelApparactusioenran Arsea nmtaibnetS e

Test Anperactusn entr;al Control A rseaby Mass Flow Calibration

N o z zl -( Ii ~D ig ita l

StandAcusto

- ~PanelI

ICompressorNotL L Area

7 Advanced DesignWind Tunnel

Central Control

19 It Test Apparatus (JITAI yse

WS O Jt Ine cto klvrg

PS~~~ TFoeaon,

"--- -

A'ap

La -

-' .. ,L. .! J

FIGURE 2-17

CONTROL CONSOLE FOR EXHAUST FLOWS IN THE JITA

14

Inc

I-OD

0~

:140

to,

404

were recorded on magnetic tape and reduced on a Scientific Engineering Labora-

tory Model 86 Digital Computer.

To assess the dynamic jet-induced forces and moments, the force balance

analog signals were recorded on a 14 track FM tape, along with the outputs

from the three ground plane potentiometers and a computer time code. The

balance and potentiometer signals were also recorded on oscillograph strip

charts, shown in Figure 2-19, for on-line monitoring. A Hewlett-Packard 5451B

Fourier Transform Analyzer, Figure 2-20, was used off-line to digitize the

dynamic data and analyze the data statistically. The HP5451B has a built-in

analog-to-digital converter and keyboard controlled statistical corr.putations

such as power spectral densities and autocorrelations. Time histories of the

balance data can also be provided for selected time segments.

Deck Motion Test Apparatus - The moving deck hardware, shown in Figure

2-15 and 2-21, consists of a simulated deck, a hydraulic actuation system, a

movable support cart, an electronic control system, and electronic/mechanical

safety devices. Two decks are available, one measuring 6 x 6 ft (1.83 x

1.83 m) and the other 3 x 3 ft (0.91 x 0.91 m). The larger deck represents

an aircraft carrier (CV) deck while the smaller deck represents the landing

platform of a non-aviation type ship such as a DD963 destroyer. The decks

have a 2.0 inch (5.08 cm) honeycomb core with 0.04 Inch (0.10 cm) aluminum

skins. This provides a lightweight structure for the fast movements required

for simulated deck motion with small scale models and the rigidity required

to avoid bending. The rigid construction has a high natural frequency and

negligible deflection under maximum jet thrust loading. The natural fre-

quencies of the deck were verified to be well over 100 Hz by a Spectral

Dynamics Corporation Real Time Analyzer. In addition, static loads were

applied to the deck at points where jet thrust loads were experienced in the

program. The measured deflection at the corner of the deck was .051 inches

(0.130 cm) with the maximum jet thrust load, indicating the rigidity of the

deck.

The hydraulic actuator system consists of a single rotary actuator for

the heaving motion and two linear actuators, located at right angles to one

another, for pitch and roll. The drive arm connected to the rotary actuator

is attached to the deck through a universal joint. The actuators arc powered

2V.

, im.

fz% &Zm '

F IGUE21ON-IN OSILORP STI HRIEO D R

__o

FIGURE 2-20

HEWLETT-PACKARD 54518 FOURIER TRANSFORM ANALYZERFOR DYNAMIC DATA REDUCTION

{I

S (

W i4:# :h .3

FIGURE 2-21DECK MOTION TEST APPARATUS

bhv a single 30 (l)ti, 3000 psi hvdrau~lit pump with W ,1 vrialrl. OiLI)LIL 1ressure itnd

flow rate. Tie ground plane and at olitLor-i are It)tlLtod a1 1 eI sl])pot

cairt notnted oil a i Lrack. I)iiring test iln.,, t . tar' ih t.11'I-( aii:iiori-- %.'t |

ho I t clamps tihrough I-beams to the floor.

"The ranges for tile deck motions are as follows:

Heave, +6 in (15.2 crin) at frequellcit-s up Lo 3 Il:., wiLiI Iii ;her;rtiucelilC o-

at lower amplitudes.

Trains]ation, +12 in (30(5 cm) Maximlunm travel from J fiXed neltaral. poinlt.

The neutral point can be varied over a 157 in (4bm) range

by movement of the catrt along tihe tracks.

Pitch, +10' at frequencies up t(, 3 liF.

Roll, +150 at frequencies up to 3 lIz.

Derivation of these ranges and frequencies is disCussed in Section 3.2.

Tile deck motion is controlled by an electronic r.ontroi systern conflistinf

of a fUlcLtionl generator for command inputs, servovolves for flow control,

amplificr circuit boards, and potentiometers for positioll inldication to 1

closed loop system. The control console is shown in! Figure 2-22. Tihe

control systet:; provides closed loop feedback position control for accurately

repeatable motion, as described in Section 3.2.

The input command signals can be either a sine wave, square wQhe, ramp

function, or sine wave superimposed onl a ramp. Tile latter can be used to

simulate take-offs and landings with the moving deck. Th, deck mrotion fre-

quency and amplitude are independent variable inputs to the control system

for the three degrees of freedom. To improve the static stiffness of the axes,

a notch filter and a strain gage torsional load feedback -ircuit ;,ere incor-

porated into the control system. Lead and lag compensation cit'cuits were

used to adjust the phase relationships between multiple axis motions and to

reduce position error.

Mechanical stops and microswitches are supplied to prevent the deck

from striking the model. Such an impact would cause considerable darmige to

the model, force balance, and deck apparatus. Tile microswitches are installed

,n the pitch and roll actuators to sense an actuato.r overtravel and provide

A si A:il to tile control system which auLonmaticailv drives tlt' t'iCl ,als'av tLo

the t, iral point and halts motion. The mechanizcai stops are dcsigncd ,itii

vis cotis dampers and rubber pads to absorb the ki ni energy o'L tic ;:,o';in;

deck.

-r, S S S -S- t'-----I- i- -- - - - - - - -

IrI

FIGURE 2-22 ~~DECK MOTION CONTROL CONSOLE4

J. '1s"I PROC;I,',I

The tLest proI)1'0a)' wA s pW. r'fornicd in Lhe ICA(IR l(t L It-racr: iion Test Appa-

r.,Lus. Li1 test vatn bi us and ranges investig!.a-tcd, aind tl e" Lt1-:L C!d Ut

ulsd irt, described eow.

3.1 TEST -'VAK1ABIES - The plrimary Lest Variab.lcs consisted ol tLh mode-l heighiL

,ab),Ve te dIoCk Alnd th- deck heyAVe, pLtCh, and rull i amplitUdU, and lreot&lel, j

AdditiC ni l test var iabL .!s included the phasene eheLWOL il to ot MoLions (e

botween pitch and roll) , the deck :- ie, and thte nzzlu pres.,ure ratios.

These test variables are illustrated in Fipg te 3-1.

SForce

FrontNlozzle _

Mode I

Mov:nq Deck H, Neutral Height

..-- -;-i, Heaving

EL .... _ _- Amplitude

Test Variables

Parameter RangesModel Nozzle Height Above Deck, 1/Dje O.HD to .10 tIc)Heaving Amplitude, h/Die 0.5 ro 1.5 (10 cm)Duck Pitch Angle, it (Aircraft Nose Up - Positive) 0 to ± 100Deck Roll Angle, 7 (Aircraft Right Wing Down - Positive) 0 to ! 150Deck Heave, Pitch, and Roll Frequencies. fh fa, f)J 0 to 3 HzOynamic Phase Angle, i 0o, 900)Nozzle Pressure Ratio, Pt Pa-b 1.1 to 4.4

Nozzle Pressure Bias Ratio, Ptlfront Ptlrear 0 to 1.0

IGrounrr, Plant Sc,,c 0 91 n x 0.91 rn, 1 83 m x 1.83 m

o Pa 0I"09 is

FIGURE 3-1TEST VARIABLES

3.I

Several model configuration variables were investigated for both the

subsonic and supersonic V/STOL models. These variabicai included the degrce

Of fuselage contouring, the number of nozzles and their irringetrent, the wing

height, and external appendages such as lift improvemient devices. These

model configuration variables are >llustrated in Figure!; 3-2 and 3-3. The

model configurations tested are defined in Figure 3-,;. The test prograo. is

summarized In Figure 3-5. A dutailed run summary is provided in Appendix A

in Volume II.

Since the deck motion variables are unique to this program, a discussion

of the derivation of the amplitudes and frequencies is felt necessary. The

amplitudes and freqeuncies were derived by scaling typical ship responses to

selected sea state conditions. The nominal design point was Sea State 3,

moderate to rough seas, with significant wave heights of 4 feet (1.22 m) and

15 knot (27.8 km/hr) winds, Reference 1. For landing platforms aboard small

ships, such as the DD963 class destroyer or the FF1052 frigate, the maximum

full scale motions were estimared to be a heave of ±8 ft. (2.44 m) at a maxi-

mum velocity of 8 ft/sec (2.44 t/sec) a roll of +10' with a period of 8

seconds, and a pitch of ±2' in 4.5 seconds. These amplitudes arv in good agree-

ment with computed values obtained from Rcfcrcncc 2. A- -an be su~n from

results of the Reference 2 computer program in Figure 3-6, the response of a

DD963 class destroyer to typical sea conditions is somewhat random in nature,

but at most given periods of time the response can be represented fairly well

by a sine wave. The maximum amplitudes for the deck motion simulator were

established by the maximum amplitudes indicated In Reference 2 and the tests

were performed with constant amplitude, sinusoldal motions. To allow for

variations in aircraft and ship headings and speeds, the full scale oondiltons

selected for the design were a heave of ±10) ft (±3.05 -n), a roll of ±15'. and

a pitch of ±10 all with a period of R ','conds.

The amplitudes are scaled by the nomiual model scale factor. The .re- i

quencies, on the other hand, are scaled by the inverse of both, the model s"cale

factor and the ratio of the full scale _jet velocLty to the node jlet vuhlc itv.

Thisi establishes flowf ield similarity between the model I.ud lai 1 cc ,ond i-

tions. The jet velocities differ only by the ratio of the sqaar*. roft 1,f t hc

3.)

Effect of Contouring

-Hiqhl Tail

d

'I -4

ý--Low Tail "

Conf ig 23

3D Fully Contoured S'm1cuntoured 2-D PlanformConfig I Config 14 Config 2

1. 13 ,in(287 c.n)

_C1 r3High

- --.. Low

S-: " 'I 3.00 in.Wing Height (7.62 cm)

Config 21, 22, 2

Nozzle ComplexityConfig 12 I

/

\i

\-LID ' Stores

Lift Improvement Device Wing Pods Nozzle ArrangementConfig 13 Config 1 1 2 Jets, 3 Jets

Config I

GP?1.0895

FIGURE 3-2SUBSONIC V/STOL MODEL CONFIGURATION VARIABLES

Lower Fuselage- LID

Bottom) View

3 jet 2-0 Planform Lift Improvement DeviceConfig 31 Config 32

f-ForceBalance

ogPstn

'-High Front View

MidProfile View T --- / Low

Coe mour tordWngHih

Confiq 3 - Config 34, 33, 31

Number of Jets, Nozzle Arrangement and Spacing

-. ~Mid Mdr~vd Fwd

Ijet 2 Jv o4r~ 1et -

SUPERSONIC V/STOL MODEL CONFIGURATION VARIABLES

CONFIC. NOZZIESNO. DESCRIPTION [ NO. -TYPE POSITION WING TAIL

Subsonic V/STOL:

1 3-D Clean 3* Fan Mid Low High11 3-D with Wing Pods 3 Fan Mid Low High12 3-D with Complex Nozzles 3 Fan Mid Low High13 3-D with 3 Sided LID 3 Fan Mid Low High14 Semi-Contoured 3 Fan Mid Low High

2 2-D Clean 3 Fan Mid Low High21 2-D with High Wing 3 Fan Mid High High22 2-D with Mid Wing 3 Fan Mid Mid High23 2-D withi Low Tail 3 - Fan Mid Low Low

4. 1naer Region PInte 3 Fan Mid - -

Supersonic V/STOL:

3 Semi-Contoured 3* f-F, 2-.t Mid Low Low31 2-D Clean 3 1-Fan,2-Jet Mid Low Low32 2-D with 3 Sided LID 3 l-Fan,2-Jet Mid Low Low33 2-D with Mid Wing 3 1-Fan,2-Jec Mid Mid Low34 2-D with High Wing 3 1-Fan,2 Jet Mid High Low35 2-D Clean 4 2 Fan,2 Jet Mid Low Low36 2-D Clean 4 2-Fan,2-Jet Fz rward Low Low38 2-D Clean 2 2 Fan Forward Low Low39 2-D Clean 2 2 Fan Mid Low Low

* Configuration also tested with only 1

front nozzle or 2 aft nozzles operating

FIGURE 3-4 CONFIGURATION SL•.•IARY

3,ý

Co NlT1(;tRATION

SUB SON I C s U I EISON I C

-'.Sins VAL bIA. [I 1 13 1.4 2 21 22 2-3 4 3 3 L 32 33ý 34 -33 36 18 39

IWIC1Tx x x x Xx XX X XX x x X X XPlITCH X X X X X x X X x

x x x x x x x x x X x x x x x

HIEAVE HOTI ON x x x x x x x x x x x x x X x X X xPITCH I IOT ION X X x X x X x XROLLIMOTION x x xx x xx x xx x X X XX x

IHlAVL FREIQUENCY x X x X N -1,11,0 i:REQLI:CY x x x xRoUl FI'Ri>UNCY x x x x

N I-LE ,1: ISSURE I:1AT I0 x

'1Ii;UST BIAS x x x x x

LI F- CR UI SEl JE'TS X

ED3IU 'MOTION.; x xS :'UL;%TED TAIT-

P.IGLRL" 3--) TEST PROGRAM SUt~lMRY

3 C

Center of DeckPlatform

Typical Deck Heave and Roll Response of DD963 Class DestroyerResults from Computer Program Based on Reference 2

5 44 Over Givern Periods, Motion

Can be Accui ately FIt %vit• i

3 Sine Wave I2 I I

-- Roll/-2 Heave-

-3 I--4 V

- -4 s - - I I J. I

- 10 20 30 40 50

Time, t - sec op01-081S.78

FIGURE 3-6

SHIP MOTION PREDICTIONS BASED ON REFERENCE 2

temperatures. Thus, for typical lift fan nozzle exit conditions where the

full scale frequency of thc monion may bý 1/8 iii, Limu model frequency required

is:

_ _ 1 1 1

.IS Scale ITTj i / F2 .iz

Factor /TT./T'j fFS MS5

Deck motions were thereflre nominall,' tested at 2 llz withi selected test. It

1 Hz and 3 llz.

3.2 TfST PROCEDURES - The test procedures followed during the program were

established to allow efficient InLegration of the static and dynamic testing.

Static [lover Testin - The jet conditions were first set at the desired

nozzle pressure ratio, utilizing the automatic pressure valves and manometer.

The deck :os ition was then remot.ly 0ositioned Lo the desired height and

attitude, based on calibrations of the roLary potentiometur on the heave

drive arm and the linear potcntiometers on the pitch and roll actuators.

Once the deck was properly positioned, the data acquisition cycle was

initiated to acquire the force balance data and the pressure data.

Static height, pitch, and roll surveys were obtained in discrete

increments with the moving deck qupport cart sat at a particular position.

To obtain data over the comnplete height range, three cart positions were

required. Generally, the Static and dynamic data were obtained in sequencu

at each cart posttion.

Dyvnauic Dt-ck :IOLiOD j'Vtill_ - Prior to oid1Litii a urtictllar duck

!Ot LOll 11-taIL ic i IOXv C .dta Were oý La nd L 0provide a rL cc)rd (o t*hu Le.-t; ploint

ill tIle COnti! tr pFintLout it-) We~ll ats thte noZle thrinS t character i sr ir. TheSeý

r vr Lrn 1,' (,r.1 w~re obtai ned with the dveck at. its neut ral I point. The ducck

m t ionl wdas Lhthe Q!ttLihlshd ut~iliLtilp, the electronlic colitrol SVSCCm,

cLibralted 1potent jolneters, peak Voltage metersi, atid a Cal ibrateLd oSci ilo0ScOp .

Mhe flotioll in each of the deck's three deg~rees of free-dom was also recordedA

On an oscillograph recorder for reference and to en1sure uiniform sintisioidal

::X t11 It'llL I U~g~l0Ln t eac Ii tSt run.

The elecctronic control systemr, shown sctieroiticatllv in Figure 3-7, twas

h igh lv reliable and p rov ided ext-c len t c-ontrol over the deck vo t ion 'l.'.Pe I orinl

S 11ce it Was a closed loop -;Ystem. Disturbances cau..'i by anozle thrust

loads, frict'ionl, spurious ale':tricai noiso, and inldtc.ed drag on the decLk WeL:rC

essentiaillv eiLiM~in.t1Od and smootht sinusoidal, Motion" ri-sulted. Ecll~~'

thie oututj,,, lvavcorn5 for heave , pitch, and roll atre ;ivkul i!,. Figu~re j-8

a desired deck motion was established, the dynamic ýaita ilc.hUiSit IOn

cycle ivas initiated. Thils involved recording the force balatnce'

the deck itot~ion potentiometer outputs, and a computer timC Code 011 tWO l.

track UFM tape recorder'; * The atnalog diita on thce tapes were frequlently ('leCKCC1

to vji-sure! that no dat~a acq0.sition problem~s occurred.

At the beginning of the pro gram, dynamic data wcre recorded for f ive

itinuties to deter:,mi.n. tlhe record le-ngth required for SjaL s Li ci) ,oC i a

11inLiti-3 analysis revealed that approxirmate'.' twc. mi ntires of datta %-as. sufI--

cient. Furt~her post rest analyses indicated that sinice the! dynarmic induccd

force and riorentL data are haisic-iily ci th~er CuIMP! exY per ''d i or 5siu I dill inl

nature, zicquiýring approximately 30 seconds of data would !)c adoequ'tate ill flit ore.

tests.

C E

0 ; E cc

0 d-

.c .n

I-

M wz

>, jo D

F- CL 1

<

LUJjIui1

6 Lo

cIifiL

- o 1

Oscilloqiaph BruJSh Recorder Ti aces

Deck Hedve fh 2 H,,

above Deck, 2 .RUn 228

0 0.5 1.0 1.5Time, I - sec

Deck Pitch f - 2 Hz

Deck Pitch i-.......I...Angle, at 01. Rju 200

deg

10~ ~~~~ *t:.I i. . . . - I . ... ... ....

0 05 1.0 1.5

Time, sec

Deck Roll f) 3 Hz

10 . 1 -1 177

Angeko a4~ I Run 212

deg . ...

0 0.5 1.0 1.5Time, t - ec

FIGURE 3-8SAMPLE DECK MOTION OUTPUT WAVIEFORMS

4 I)ATA U:I)UcI'I}ON AND [UTI'EAIT'AIIL[TY

JetL-induced force and momint data weru obtained It both static hover

condiLiotis and at conditions with deck motion. Due to the different means of

acquiring the data at these conditions, significantly different procedures

were used for data reduction. Theso procedures are discussed below.

4.1 STATIC HOVER DATA REDUCTION - For the static hover tests, data were

recorded and conditioned as described in Section 3.1 on a Datum Model 120

DDAS. The digitized data were input to a Systems Engineerirg Laboratory Model

86 computer to calculate the induced forces and moments acting on the air-

frame. The computer program utilizes a second order force balance calibration

consisting of a 6 -x 6 coefficient matrix.

The lift was determined directly from the single axial force gage. The

axial force and the pitching moment were determined from the two gages aligned

parallel to the model centerline. The side force and the rolling moment were

determined from the two gages perpendicular to the model centerline. The

yawing moment was determined from the moment element gage. All moment com-

putations use a representative center of gravity location for each model.

Following the basic force and moment computations, the results were non-

dimensionalized by the thrust determined from the nozzle calibrations and

the appropriate dimension as follows:

Induced Lift, Induced Axial Force,

CFNS = CFAS =-FA

Induced Pitching Moment, Induced Side Force,

SPit, FYCPMS CFYS

FGC FG

Induced Rolling Moment, Induced Yawing Moment,

CICIS = CYMS 'F(,b FGb

The model height above the deck was non-dimensinnalized by the equivalent

nozzle exit diameter which was computed as follows:=,4 AT

Equivalent Nozzle Diameter, Die

K

where A =7 = Total combined exit area of all nozzles

j~-4

-4 4"

.= Exit diamnetcr of each ioz1ze

.1n1d K = NuILLber of 1. ]' .IeS

4. 2 )YNAMI(C DATA REDL:CTION - As described in Sect-ion 3.1, Lhe dyntamic daLa

we2re recorded in aalinlog form on F!1 recorders. These data ire illsp ut oil corn-

Mathd to .i llewlett-I'ackaird 5451B Fourier Analyzer which digitize- the data

to plrovide time histories or allow statistical computations.

For the dynamic data comptitatri( ns, tOWe saeL, haS.ic c(tl /Lions dufinused ins

Section 4.1 were used to compute tile induced lift, pitching moment, and ro0I-

ing moment as functions of time. The balance response was more than adequate

to cover the frequency range of interest (0 to approx. 20 Hz). To verify

that tL1e natural frequencies of the model/force balance system were above

20 liz and therefore would soLt CAULo Spurious signal interrac ion0s, a Spectral

Dynamics Corporation Real Time Analyzer was used. As can be scen in Figure

4-1, the natural frequencies were above the range of interest.

Verticjior Yawing Axis

"i"~ °-.7 .

4

Longitudinal / Lateralor Rolling Axis or Pitching Axis

Model Frequencies (Hz)

Acceleration Direction 3-D Subsonic 2-0 Supersonic 2-D SupersonicViSTOL V/STOL - 3 Jet V/STOL - 2 Jet

Configuration 1 Configuration 31 Configuration 38

1. Vertical (Ltift) 149.6 127.0 142.02. Lateral (Side) 33.8 25.6 26.43. Longitudinal (Axial) 40.4 20.2 20.6

4. Pitch 40.2 27.0 30.25. Roll 52.6 25.8 26.6

6. Yaw 25.6 15.6 26.6

OP7T1-072 27

FIGURE 4-1

MODEL NATURAL RESONANCE FREQUENCIES

45

The basie statistical conmptItat ions p rimar il y (I Lti I zed in LIi.; ill V L Lgla-

ttoi were tIIV poWe r spect ra I dens i ty (PS I)), aind LtIe cir-ss power 'Lrl ri

density (CSI)) which are define(! in Figure 4-2. The ac oI t'Iorel at ion and

the cross correlation were uied to a limited extent but are also defined.

4.3 DATA REPEATABILITY - As discussed in Section 3.3, deck position, attitude,

and motions were set precisely resulting in repeatable output force and

moment data. An example of the repeatability of the static induced lift for

the subsonic V/SIOL configuration is presented in Figure 4-3. Typical repeat-

ability ot the dynamic induced lift data for a heaving deck is shown in

Figure 4-4 for the supersonic configuration. Good repeatability is apparent

for both the static hover and the dynamic data.

46

rCC

L" t.. 0 00 )('C - (v ~ Q m C42

4O c ~ w4 V (P. r- ClU 0CV.-'. m jd. "0 ) mEf V04 j

A(V :3 -OC - .,.J4 VL M 14 .V

iV.-JC mr- (A0V".9-C- Vm ).-. o4i> u' c0- r$4jU0 C_ 4- V)

C 4 0 X- r-V. l)C 4.-' Jmm -4-"0- 3t WV" uC 4) -

in1

Cv 4)2 WC - 0.)C " .0 .-C). 0- 4) 4) V 'r)V 0''

01 CV) : C >-Q V C-4 VU CV W:-T4) 0 Qt 4) I-4 V -"4 ) SC '0 a)

4404 = M- a)JC(01,-U0 T;A0£- cc',C .

4d)> x CC 4;4 A '> w J-Jc w4 V~-V~- (tc0 C w4 .0 -M v 0 £-C co 'A .,'' C -i 0"0'

4) 0 R "C wA V -'A4 V -4 A4 '-(A lC EV C

Lt£ E0 $4Crh I-V cfC w- u C- Vmn 22 C) i20 a) Ctl ' 00E j~4 3U) ~ - _

ia 044M$4u C Ur C' C> "0u44 CUL -0' a L; 4 t

44 - 0 44

4z))

x ~~ W-x > - .

FE = cC c-

- ~ ~4) -AjU

II cr (r,

-~u s', 0 L) X I.. "

...- . . ...... . .. . .. . .. -

- -- ---- - ------

~ . .. . .. ... ... .

* U,

>I

N c

Z OD* lii I

M ci (

, -I .

. •. . . 4C.(

_ * * .0 4. - - 4

* : •°. 4 .,

o Wý

*... W - - • -

o~ M 10c

/ , . .. I.-

-'4' ! 3

S . I .,

I

0•'- •.-I a~pu

Supersonic V/STOL Contiguration 3H/Die 3 . 2 7 h/DOe- 1.0 th 2 Hz a0 = 00

0.2

Configuration 3 (228.3)

0.1

0

-*0.1

-0.2

- 0.2

"Configuration 3 (235.2)

Z 0.1

0-

-0.1 v v

-0.2 -0 0.5 1 0 2.0 2.5 3.0

Time, t - secopTII 080S 89

FIGURE 4-4DYNAMIC DATA REPEATABILITY

"t ,'

5. DISCUSSION OF RESULTIS

Tho ier-lnduced aerodynamics of V/STOL aircraft in hovwr over 1 movling

deck were experimentally investigated. The effects of a number of V/SW.10 air-

craft configuration variables applicable to sbLsonic and supersonic designs

were evaluated parametrically, both at staLic hover and dynamic deck motion

conditions. The data obtained at static hover conditions, which are pre!sented

in Section 5.1, indicate the general aerodynamic characteristics and serve as

a basis of comparison for the data obtained with dynamic dock motion.

The dynamic force and moment data presented in Section 5.2 indicate the

effects of deck heave, pitch, and roll on the induced forces and moments.

The frequency content and the phase relationships between the sinusoidal deck

motions and the aircraft responses are also discussed. Based on the static

and dynamic data, V/STOL aircraft design and testing guidelines are defined.

Empirical methods of predicting the dynamic response to deck motion are

described in Section 5.3.

5.1 STATIC HOVER DATA - The jet-induced aerodynamic data obtained at sttic

hover conditions at fixed heights and dock attitudes provide a significant

technology base for evaluating V/STOL aircraft configuration effects as well

as for indicating the basic jet induced aerodynamic trends which can be expected

with deck motion.

Static hover data are presented for both subsonic and supersonic V/STOL

configurations. Emphasis was placed on the induced lift characteristics since

this is the critical performance parameter for V/STOL aircraft. However,

induced pitching and rolling moment data are also presented as functions of

height for the basic configurations and as functions cf deck pitch and

roll where the variations in the moments become significant. Mieasurements

were also made of induced side force, axial force (drag), and va.:inq moment.

but variations in these parameters were insignificant and are therefore nct

presented in Volume I. All of the static induced aerodynamic data are pre-

sented in plotted form in Appendix B in Volume 1I of this report.

5.1.1 Subsonic V/STOL Configuration - The basic advanced subsonic V STOI.

aircraft configuration, shown in Figure 2-3, represents a three-nozzle, low

wing vehicle with a forebody mounted lift fan, and two lift/cruise fans with

tilt nacelles mounted over the wing. The cntiguration variables include

model surface contour, nozzle arrangerent, lift improvement devices (LID's),

stores, wing height and nozzle vectoring vanes. The test variables include

5 0

height above the deck, deck pi tch and rol I i angI. tc, deak si ,e, zz N I) ] re -z ir e

rat o, and thrust bias.

.ffect of Height - 'rTe jet-induced aerodydnalic l ft lif lhol L11 1 y" 1' n-

toured (3-1)), three nozzle subsonic V/SFO], model Is shown in ll Pgirc -- la.

Close L0 the deck, near gear height, grounld jeL-induced cntrainment causes a

lift loss of approximately 3 percent of the net thrust. Further away froma

the deck, at a height of two equivalent n7ozzle diamet.rs (1l/I).e proxi- -1

matelv 14 ft or 4.3m full scale), the induced lift peaks at about- .. percent

lift gain. Out of ground effects (above 50 ft or 15.2m full scale), no

fcuntain frorms and only a minimal-induced -lift loss of 0.5 percent results

from free-jet flow entrainment over L:i aircraft surfacos.

The relative strengrhs of the fountain and suckdown are clearly indicated

in Figure 5-1b, where separate measurements of the fountain strength are show:.

Sfro., tests of an inner region plate model (Figure 2-7). Since the founLain

Supwash flow is concentrated in the inner region, i.e. the area bounded 1%. the

three nozzles, the induced lift in this region is representative of the feuntain

strength. An estimate of the suckdown forces is computed by subtractini" tihe

fountain force from the net induced lift measured with the corplete j- framemodel. As shown in Figure 5-lb, this three nozzle arrangement has a moderately

strong fountain which results in a peak lift gain of 5 porcenL at a 1ici!i of

1.5 nozzle diameters.

Effect of Deck Pitch and Roll Angles - The induced lift and pitching

moment for thv 3-D model are shown in Figure 5-2 as a function o" deck pitch

angle. Close to the deck, induced lift and pitching moment vary ;ignificantlv

with pitch angle. Further away, at an ji, D. of 5 (35 ft or 10.-.n full scale) and

above, induced lift and pitching moment are insensitive to pt'C-. angle.

Similarly, close to the ground induced lift and rolling nanoanet vary

significantly with deck roll angle, as shown in Figure 5-3. .; with pita!.,

roll angle has little effect at a height of five diameters and above.

Effect of Deck Size - As described in Section 3, two ground planes t..ere

used to simulate two different sizes of ship decks, one 3 x 3 ft (0.9] x 0.922m)

representin6 thc small landing platform on a DD963 class destrovcr and the

other 6 x 6 ft (1.83 x 1.83m) representing the landing deck on a cenlveu;tiUnrii

aircraft carrier.

51

. , .. .. ...... - --.... ..... ..

Li

* .• -* I ** ....-..... . . %

-i--

u 9t i_- _ i :- - ,

Sl • m. - ,- ,,LU

I a

e,,. I --- -- -- --- --- I

" ' i9 " L

III

I. : • :! : I * * ]

S . ... A ..... . ..

,o~~~~~~c eq .. +!1Z i Y+=+++I aU

; .* I I . I I *.

S. .. + .. = .;_ I.._ _ l•_+ .w_

0~ I 0

16--

--- -- + - -C. . .. -- + -t -+--.. . - - . . . • . . . ,-. .

0.. ..0I . ..I ' ' I

Am I "H'I anu

| *.0--,

.. .... ..... .. .. .. .

......-.. -- - -

.. ... .. .. \ ...

L6.

----- -- - -- ------ -w--- --

II.

42..U-

0 c

I ------- --

.. .. .. . 0. ...a

............. ... -----

... .- .0

& -

0 -

C) ctI4 I I. fj

CC

>j (4

- -. -I -.

... ..... . ----

~~ I

c c4 a.

()o 0 0

ILiu

LU______

zr I,

0 0

>

I-.r

LiiC, co6 0 6 6 0-

Subsonic VISTOL -Roll EffectsConfiguration I a 0 NPR -1.5

0.004

0 .0 0 2 -- --- - - ----- --------- - --

.. . . . . . . . . . . . . .. . . . - - -

-i0.002 -A 50.....

0 .[. .. ... ... ... .

-0.004 ............:

-1 -8 916o

-16 __0 1

r.' r ." 7 i . ant- nr m r m n :.a z• • i5.

At static hover, the deck size has little effect on the induced lift,

as shown in Figure 5-4. 'This is also the cast, at various dciiscrete deck roll

and pitch angles as well as for tile responses to dynam ic deck not ioer. Tiheset

data iare presented in the Appendic's 1; and C in Vol)imo I I.

For th s program, the ai rc-ra ft models were ccntcrcud di ret't I v •ev. tic

deck. Thus, the impinging jet flows and subsequent recirculatiog flowfields

were similar for both deck sizes. Other interactions may be morc significant

for the small landing platform due to the proximity of the superstructure and

the greater likelihood that all of the jets do not impinge directly on the

deck surface. Since the small deck offers more potential problems affecting

V/STOL operations, the 3 x 3 ft deck was used for the majority of the tests.

Effect of Model Surface Contouring - An important objective of this

investigation was to determine the degree of configuration simulation required

for jet/lift interaction testing. The subsonic configuration was tested

(1) as a fully contoured model, (2) as a semi-contoured half model with con-

toured lower fuselage and raised tail, and (3) as a simplified 2-D planform

model. The results shown in Figure 5-5, indicate the effects of body contour

details on the induced lift.

Similar trends are indicated in the data for each of these models, with

the peak induced lift occurring at nearly the same height. However, the

planform models have a significantly higher induced lift in ground effect.

The semi-contoured model has a higher induced lift near gear height, but at

1.5 nozzle diameters and above the results agree with the fully contoured

model. A contouring effect is apparent on the planform models tip to an H/Dfa

of 5.

Company funded studies performed on a similar planform model instru-

mented with numerous surface pressure taps, Reference 3, showed that most of

the fountain force is concentrated between the two rear nozzles rather than

near the central fountain region. Thus, the increment between the induced

lift of the 3-D and planform models is attributed to differences in contouring

in the region of fountain impingement. The 3-1) model has upward curvature in

this region, thus producing a ,,reaker force than on the planform model. The

semi-contoured model has a portion of thi.s region contoured and thus provides

netter agreement with the 3-D model. Those results indicate that although a

simple planform model can be used in low cost configuration screening tests,

some form of contoured model is required for obtaining accurate induced

aerodynamic data in ground effect.

5 t

r~d . ..

I j 4

.... - I ----

0 OD 0

0i x

* Wi P~flPU

x 9

04

.. ...........-- -.--.-----.-

Lo ~ ~ --- -- ------------ - -- --

c~ LL

-2 z a i

_r 0

o *oCD CN

-~ N~ 1. Ci

On the planform model, testing was conducted wiLh thli horizontal tail in Ithe same plane as the wing and fuselage and also In an eleva ted plane, as on

the contoured models. Placing the horizontal tail in the lower plane r,-duces

the induced lift. This is attributed to a slight increase in suckdown ,i1 theLIjv

aft-end due to the proximity of the tail tLo the rear nzzles. The recessity

of placing the wings and tails in the proper plane on a planform model is

therefore believed to he dependent on the location of the nozzles relative

to these surfaces.

Effect of Lift Improvement Devices and Stores - The fountain upwash

momentum can be effectively converted to positive lift on the airframethrough the use of properly designed lift improvement devies (lll)'s) mounted

on the lower fuselage, as shown in Figure 5-6. The lID's act to .Ltenil;Jte,

the impinging fountain flow and :edirect it downward, providini; an increased

lift up to an HI/D. (if about 2. Near the deck, where lift is especially

critical to ViSTCL aircraft mission performance, the. LI D's improve the in-

duced lift dramatically, more than 10 percent. Although a V/STOL1 aircraft

cannot perform a V'TO with more Fayload than it can hover with out -f1 ground

effect (OGE), the substantial lift gain car be used t,, ;,rovide rapid ac'cl-

eration through the ground effects region and Lo offset any jidverse effects,

such as result from exhaust gas ingestion. To minimize the drag penalty in

wing-borne flight, the lateral fence of the LID could he retractable.

The LID's are also effective even at high roil angles as shown in

Figure 5-7. The induced lift remains positive over most of the range in-

dicating that the LID span is sufficient to capture the majority of the

fountain. As shown in Figure 5-8, the rolling moment is adversely affected

at an H/D = 0.8, presumably due to the impingement of the fountain on theJe

longitudinal strakes.

Pods were installed along the lower wing surfaces to simulate aircrat ,

stores. These improved the induced lift, but only near tLe dvck, as shovn in

Figure 5-9. The pods trap the fountain upwash flow in a manner similar to

LID's, but there is no lateral fence to contain the flow. Also, the pods

tested do not extend between the two rear nozzles, where the highest fountain

momentum exists.

Effect of Wing Height - Increasing the wing height on the plantorr' mo-del

increases the induced lift 2 to 3 percent close to the deck, as shown in

Figure 5-10. This is attributed t,, a reducLion in sutckdo•n (,n the V in, su,-

face. It should be noted that the nozzle ex:it plane remained conctlant in

61

- ~ ~ ~ ~ -- --- -- .--.----.---

-~ c r . . . . .

. . .. . .. .

Z 6i

uU,

0)

0)

... ... .. N

... ......... --- -- - -

----- -- ----- -- -

co CN (D

620

Subsonic V/STOL - Effect of LID

H/OjeO08Se =00

0.08.. . .... .--. . ........ r - ----i -- .. .........

.. ..... ... Run~ No. Configuration

A 91 1 (Clean)

0 111 13 iLID~l0.04 T......... .... ....

--- --- * -- * - I ---- -----.....

-6

--0.04----

-0.08 + I+

-0. 12 1 J-16 -8 0 8 16

Poll Angle,) deg GP78 08".;6

(a) H/D e=0 8

FIGURE 5-7SUBSONIC V/STOL ROLL EFFECTS ON INDUCED LIFT

WITH LIFT IMPROVEMENT DEVICES INSTALLED

6 1

Subsonic VSTQL .E~ffpct of LIDH/Die ~2.0 Lt 0'

0.04I

R un No- Configuration

0.02 tr

†††††††††††††††††††††††††- ..*.-..

-.0 2 8.. 0.. ... .. . .. ...1 6. . - -- --------

-o l A-l -- -e ------ .. .. ... . .. '.

mbHDe 2

-U-06-16 -8 0 161RollAngl, dg GP8 08S 2

(b HDi .0

Subsonic V/STOL -Effect of LIDH/Dje 0.8 u0 0

0.0 12 .-- --- - -----------

Auns Confiyuration. I

0.0................. ....................

0.08...........

C

-0.004 ....

-0.008 I i1~~

I I

-0.012--16 80 8 U t

Roll Angle, I deg P639a

(a) H/0D 0 8

FIGURE 5-8SUBSONIC V/STOL ROLL EFFECTS ON INDUCED ROLLING MOMENT

WITH LIFT IMPROVEMENT DEVICES INSTALLED

Subsonic V/STOL - Effect of LIDH/Die ~2.0 a 00

0.006. . . . . .

* Runt Configuration

0 1 8. 16? 1 ice.

0.0..........

-0.002 ....... . .. ... . ......

0 I- .- - -...... ... t . .. ... .. ..

-0.002 .L ...... ~ ....- ~-16 - 0 8A

FIUR 5-8(C0c8ud16

SUBSONIC V/STOL ROLL EFFECTS ON INDUCED ROLLING MOMENTWITH LIFT IMPROVEMENT DEVICES INSTALLED

.~~~ .... .

... ... .... ...

.. . . .. . . ... ..

0 in

I.!

cc,

I I

.1. Czoa;L

--- ----- --- ....... ------...... .

.,0 .. .. . . .. ..

thu Saflh. jil1t1110 as LtIhe 1 0ow W i;1,: I" I- LileSL' t1St:i. Out at cc mid pro(xiM1t I

the0 w8iigV llitii g hald 1i0 It ut:L.

1:1 fur of Nozzle Ar ratIIeMen rII - The number and .irratigemunl [tOf liC) ZZl. Ieihas

.1 pIrttnotinCed e ffect on induced I ift Las A hoytI in Ft gore 5-1 1 for thI e 3-1) mode l.

Whn nl oejut (1-h10 forwarld I1 t ft .1a1) i S 1prtig noL fountain forms andtife inucdUL2 lift consists ml;of suckdowvn, resut- Ling inl an1 8.5 percent lift

loss at geinr height. FOec theL two-jet con! i glrsuIlLion), ru p rsen i ing a dual tilt:

nace lie design, in creased stIuckdowni occurs, whtichi over(0Icomes the weak to tin Lainl

iarmed between die jets. This results in a lift loss of 10 percent of theA

thrust at gear li~t. On the thiree-jet cent igurat ion, aI fairly strong foun-

tami forms whir siuits in a lift less of only 3 percent at gear height and

aI peak' lift gain of nearly 2 percent at an Il/D, of 2.

Effect of 'Nozzle Simulation and Operation -Accurate simulation of thle

nozzle geometry, die airframec geometry near the nozzle e!xito, and the exhaust

flow conditions is part icularlx' impo rtant in. order to provide rel2istic

results, since flow entrainment is strongest in the region of high jet ve-lo-

Cities. The effects On thfe tinduced! Ii ft of adding pitch and yaw vanes and a

hub ceniterbodv to thfe front nozzle and vx-; vanes' to the rear nozzles are

p resent~ed in Figure 5-12. Thle comp)elex nozo c]s were- found to reduce the-

induced lift near the deck by as much as, 2 percent. Fromi the caor-ýany funded

louvers- and vanes were found t.Lo alterI tLte £1ow! juld stalgnat-ionl reaIS, tItus

inhibittring flow lotAo the inner reg ion avd reduicing fcunta in s trt~ngrlh

Incrcat ilop tine nozzle pressure rat te (NP'R) from a typicaLl I ift fain value

of 1. 1 %w-'th -ijhsonic nozzle fjLow. to a direct IIft LJet condition with ic:I

f 1ev, NPIk 0a 2 (, tetl uCus tit:e hidl~ Ucd lift nearl thle ground app r X ima tC,u Ipu(rccti,,I is1SIL-WII illigr 3-13. No effect is -seen UGh'. 111C efiect of

11,o71l1 l!-etsulrt' rati to d icaiCeS that tes ringp With tlt hc roper~l f') I sin IAe

nozz,:le eiti 'Ltich luimber and! ':xhiiMiis .ý uuu is itcuite:d to) ebtinLIl a1t11 o

LI- 5;) Iul~itIon (It -It re irulti agI I'w j i] nd t!.t: inlduce] tiCrodttt..itucs.

* ain' jr i''(,I itt: Lest!, Wi Lli tnu stbo'xL: lft igI~rrat ,1't -,Were cotidliLetd Witha ~~8S at i .3, felt t's..u! t lo [In ~Il 1'ie! ,11 II a rpliij(ls~s n

T' I i' Ill! a, d It I a to i':,V Ot it it t tilt1' thlrilst ';ut it it 't4''

I f L:1-'1i '' I' IVtn I I r0i' 1ac i tuz hC's L'1, II O ti)Y .lit di ht 11"I

of 3 ptt: I-ceut

-i

rr

j I I

C

� � II . -

*1 .--........* . . ¶

* I - - . . I

U-U-

LU w I!

2I C,

043 -g. �- I

--.-. . -� I* . .

C * . . : -

C ____ *1A *

- *-.. C.,I' -. z

* . --- .

- -, N I-1II . I

* I

c*..J0 0

0 0 .� 0

1

V

ri -- '--- ------ - ,r.0

-4

-,C

4,.-

*i-

S. . .. . . .. - -- -.... .. ,

m CL

I .. .- '

........ .. . . ..... ------ I WdJ

iI I -

C' . .--- ---------

' • t . . i

o• --... .•... .- . 1 '1 ,

C -

C- i - ,- - i2

N Lb

- - -i

, __ ,i v , 'I , , i-, i i

I

-- -- -

U-w

u.

LU NLoil z

o il ----- -- -- -- - ----- - to 0 . . • ;

.J I ;-I2. ..

00

- -- .

!, .. . . . . . . .I.-.................... .. 1.........-.... z

- i.A. ... I.. . * i < . o

Si , :' : % I

I'-

CL

i : . - "r----; . .... t . .. .... I ........ .' "

z .. .-. -,el .

N _ ...• , ,--

- - - - -

.. . . . ... _............ u o

S,,. :. i I . ,-J

€. i I i - i--------I--s

"1 -.. . .. "Li, .

00

----- --- ---- - -----------, ---- --- - - -

. .. U

1u/ . I

Ui- ,

0 " 0 " 0 0 I

r - .- -- -- . -- --- -- . . . . --- _ L-.-- ---- --

0 0 0C0D

-• - : ! -% ! ! • !IS... .. .i . . . . .. . ... . .. . .. . : . ... . ; .. . : _ . . . • . .:- _J -... ...

! ' • " • ; " " i ' i

.. . ... .. .. ..

0 ~ - 7..,-'----------d

a r

LA.

ILL LL

Ij ccII ~ i

Ic 0 . . .

oL------- -- - ------ ----

C CZ

0 0- --- - - ---- - -.. .. ...

5.1*2 Supersonic V/STOL Con figuration - The supersouic V/STO1. (.onfig-

uraLiOns investigated (Figure 2-10) represe. a vr ricty of advainced designs.

The primary con fIguraction represents either ;I thrvo- or lon r-noz ?]- Veil IL'

with either a single or dual forward 1 I ft fan (s) And two vec:toring aft Ii ft/

cruise .lets. An alternate configuration represents a two-no7.7]le veh icle with

a single forward lift fan and a single aft lift fan, each driven by a turbo-

fan engine mounted over the wing. The configuration variables included model

surface contouring, nozzle arrangement and spacing, LID's and wing height.

The test variables included height above the deck, deck pitch and roll angles, v

and thrust bias. It should be noted that these -4 were conducted at the

same heights as for the subsonic V/STOL configur. .on. The heights are non-

dimensionalized by the equivalent jet diameter, which varies for each con-

figuration.

Effect of Height - Induced lift characteristics at static hover condi-

tions for the three-nozzle supersonic V/STOI. model with a contoured lower

surface are presented in Figure 5-15. The suckdown is substantially greater

than for the subsonic configuration, since the ratio of planform area to total

jet exit arc i was approximately 5 times larger. In addition, the rear jets

are much closer together, reducing the fountain strength. Thus, at gear

height, the induced lift loss is approximately 20 percent of thrust, and OGE

approximately 2 percent. Other data obtained in this program and in MCAIR

company funded studies indicate the lift loss for this configuration is highly

dependent on nozzle arrangement and geometry, with substantially lower lift

loss occurring for certain configurations.

Effect of Deck Pitch and Roll Angles - The induced lift and pitching

moment data for the three-nozzle semi-contoured model are presented in Figure

5-16 as a function of deck pitch angle. Induced lift is relatively insensi-

tive to pitch angle, even close to the deck. This occurs since the fountain

strength is relatively weak. Pitching moment on the other hdnd is sensitive

to pitch angle at an H/D. of 1.7 (7 ft. or 2.1m full scale) or less.j eThe deck roll angle has only a slight effect on induced lift and rolling

moment ICE as shown in Figure 5-17, also due to the weak fountain. The

Induced rolling moment tends to be destabIIi;jng, since increasing the roll

angle tn:reases the roling mo:aent. Role]ing the deck pushes the fountain

tr, the opposite side of the fuse]lage, thus inducing more roll on the .irframe.

7,4

S. . . .. ; . . . . . . ... . . . . . . . . . . .. . .,

N

* 0

N . , : .

4.. .........

C)S.. .. . .. .. . 7 - ' - - -: • . . . •i , . .J - --------- --- • ---- -

LUl

I.)

o ---- OD >-

o .. .. . ..... . --.. . . .. --- I.I-li, . . z,.

I - I .,,, -S.. ! ,iI . , C . . .

- - --- --

o .. U: ..'A-.: . i. I,),

-- .. . . . . . . . . ..- , • . .. -------- - - -- - : -z-. , ,

SI-. ! •

I In

•.-ir" i' H] I)aon)1)II

/ ._

Supersonic ViSTQL - Pitch EffectsConfiguration 3 Contoured Lower Fuselage 0 =

0

--0.04 ---- -- .. . ... ... . . .... ... ..

-0.08- -1~ ~ ~ - 12 ----- -268-- - --- ------

o + 1.74 -267S3.23 270

*1Ia 8.16 272

9 13.0 4- 277

-0.12I

C

-0. 16

-0.2-

-0.241 16 08 (J 816

Pitch Angle, aL deg ~7-i-'a) induced Lift

FIGURE 5-163 JET SUPERSONIC V/STOL STATIC PITCH EFFECTS

tv

Supersonic V/STOL - Pitch EffectsConfiguration 3 Contoured Lower Fuselage 0

0 12 .-

H/ 10 Ru, Nu.-

0 127 268

+ 1 74 26'0.08 U 323 270 ~ :.- . . . . . .

A 8 16 '72

.- 004.... -----------

Eo

S --0.04 .... .... ....

C .. .. .... . .. . .

-0.08 -

-0.12--165 8 C) 8 16

Pitch Angle, , deg r1'a&089S 72

b) Indu~ed Pitching Mome~nt

FIGURE 5-16 (Concluded)

3 JET SUPERSONIC V.'STOL STATIC PITCH EFFECTS

Supersonic V/STOL - Roll Effects i

Configuration 3 Contoured Lower Fuselage u,0

------------------------------------------------

-0.04 .......

m ~ -

-0.08

U. I. H/Di Run No.-JI 1 33 229

0 3.27 233-0) 816 239

-I 1317 242

-0.20 I-0.24

-16 -8 0 8 16LRoll Ariqie, (leg Gr~b 0895 931

a) Induced Lift

FIGURE 5-17 '

3 JET SUPERSONIC V'ISTOL STATIC ROLL EFFECTS I

Supersonic V/STOL -Roll EffectsConfiguration 3 Contoured Lower Fuselage a 00

0.006HIDe Run No .

.* 1 33 2.19 .. ... ....... .. .. . - - -- .. .. -- - -

a 3.27 233I I9

0.004 8.. ~ 8 16 .. . ... .. ........ ----

1 3 17 242

0.002----- --

--------0- -- ..... ------- .. ... ---- ---

-- -- -- - - -

-0002 -- --

Z 04

0.006-0 60 8---- 0- --16---- ....... ... .. ..---

3... JE.SPRSNI... ST. STTI ROLL. .. FF---CTS-

1 0" it t'l !' tiI tAdt lit ikit !i t, klu i-H. i- . tr I w t ur.

'Iontour I t uittasa Lt, "I lI tt (I I L S'. 1'' 1t l 1t Vittisr ti r 10 yerii

I I cL ot geII), thert.1 'v redo'.L L i n duts t 'ni td n ,~ v 1wi ivii t ij pruuh>:1 in vsi . uu it II marato i t il sIl t ruti It I i It li.' lx 1 t It I I kit rt,;lttri t .ii ! , t;I ntl- v iort iirt:I,Itch 15,eh -ei' Il, tý

hut~on the ae t u' i.: Lv I *ll t. C. 19 t L LI 11 1 i!~ It hn t Iii it p1ji,)its1

tue ii clizi

menlt: 0of t Ito no z zle e xitLs r . iii bCt It te II Qi utsI 1ý'.

Effoc1 t of Thrust I13J las - TheI:2 L2ixt Of ILtsrttstL 1:i . t~eer 01 th hi fLunal

liioz;:l? Aind thu .f L 11 fPt: niAisel? tiu Zz I v.< . s 11cesL g I Ld it sta i lit r Lon

isS t'tlSIti(' Lo thrust tials. i1htŽ -Il-i -;pt u iL Ik;! is tO_ td\'t abOlldlt 3

percctLt ofth L ilt' ts providei d h'ý : t a fI V k i it I' Ial.1tt is powsv '-o Li llth

I itCt is mnSelS i. L ix L o c it i:1, it I~s 0(i.

Wih nilic L oen nl ilt t.IkL~ II ino htotlttlin fOrMi'' theinu.cI

lift L4 nsiStS uL'tlttt of a kkJ . I iM4- L I I'. tic I' j i '. ý ItLt tIt tCtri.t

nozzle !.Ita it,. Fiýýurt 1 tIc Ltt i s nt . jt-'l:I

the tWo reair nuOzzes Opez-;ting, twi]ndlui ii f is ''II Iru~ 13 putL

Ef fe:t o f 1.11' S - OthCC: cli b L otI atdti:in l.1iD' s tt, Ltlt- thre- jet stipersen

illanforri Plodel is shown-1 in I FinuLrc i-2. Thulii) iitierea.se tnt itidUceti Iitt

by 8 po rc eat at geatr I:u''i lis a ýusttstanLi at incrUt'i so, hut. thle s~ite

indicated that careful taL IicriIb tof t~lc antidil, 10n1i, i0t1, 1:1 icccc1l IOf the LID's can increaset: tc itid ted 1 i ft Sy as TMttoh a>. 20 ;erCet Lit iirust.

Winh , Owiide s ten oI f L e t -.- c r 1se 1~ neL 11 It h. i:-I or era t io0.1 1. 1 W.'s d:~::

be gix'on careful att~ent~ionl k:trb:. i!! tilt- iesiý;n Of a. T.clr:: t.Aso

the sttbsonic cunjfjigurut ton, the 1.11)'i are eff.ect ie at roil, as s-hotnm

th1 inllse MAt Ai K i !iqurc - ;22. Vuw''s t'VVS IA~ ont- cWte rOI-Mi::4

mo)ment are apparent in "tc5-.

rA1t Lio in sttL, f - I L .L, 1t. L !L o

th1 Ow in . ''2 ll liei.L. . l: a' et 1 ot~i

-N m

. ~ ~ ~ ~ ~ ~ ~ . . . . .. - - - - -- -(1

I I

N NL

.. . .. . . --

II-.

............................ .

I I ----------- ----

.. .........

. .r - .- ..........

..... ..... .. u

- o SUM

±--f- 50... ... ... .-.. ..

.. .... . ......

2 I-. .. . .. .. .. . . .

Lc 0tq CC

L5i T ....

> ... .. '~*~

0

6 4 wL.................

.- .. .... ... ..U

.... .... .. ... .... A .... .... .... .

j Lj

.............

ro

(N

NN

-$! LU

LU

Oj 1' -Ij~ panpu

831

LU

c w

uu.(cc

II~~L - *iq

-~~F --------

.. . . .. ..

4,... ..... ....

.. .. ... .. . ... ..

I U7

IV - iN i popu

Supers(c-iic V/STOL -Effect of LID3 Jet o 00

m a

0 .12I -- - - - - --- --------t. .. ..

I . IConfigura'ion Run No.

................................... ...... ý1Cýn 29,26-

-0-6 .......... ............. ...........--

. 20

-0.241

--028 ý- .. -

.. .... ...

-0.32 L .. 7-16 -80 8 16

Roll A'- g'P (1e (ýq R~~

FIGURE 5-22SUPERSONIC V' STOL ROLL EFFECTS ON INDUCED LIFT WIT!I LIFT IMPROVEMENT

DEVICES INSTALL.ED

q :I OD *.

*..............v ...

* ............

-i t :: 0

. ý . ' : : ' " * .... ... 1 : . .

U. u u

0.1

C N

(N -j

-h e-

(n V -- -

-JI 4) I (

. . .. . . . . u

* Ii

*~p- 1),. . . . .

C 8-.-

I1I-ILec L o I NO I L'liA I IdJ.11 Lohl.'A- Nc." II ir gvnint-1 L I Id S pý(ic 1u

111i 1 111 LIC 111 0 011i L~ Ii Iic Ci i i ~Id tIltL iV d -'' dlVILI Iiii S h) I d itd I t i k Il t Int

tI LWO-r'Il on I-ro %I: k' iVcrst abv I vt -a z -, Lt- il gFiur I- Lg)L

Inc reased In d ucedt I I' ft IS e v Iden11t fo 0 ,t lie 1- 1 r -n .1 1) p1 a ~f ro rm con If f i I-

u r at i on i n F Ig u re 3-2S. I'theI inc r ea se Isq-at t r I bu ted.( t o I os suckdown aIn d a

s t r n go r fo un t a in. The s;ue kdown,:i I I ower becausI-Ie the n0ZZ cI CS ;re nearer thle

edge of thle planf orm, causing less airva to be aIf fe te.Ld f rom cnt rainment I)% the

ground jet flows, In addition, moving the front lift fanls i orward to increase

thle svacing; result-s inl a 2. to 5 peQrcentL highier Induced lift IGE. at tile Same

non 1)naIil thrust so lit NO var iILi Ots ill tOIFUS t 1)lsWere i nvcstigl~ted o11 the

f oar-jet configuration.

The induced li fu and pitching, moment data for thoe four-Jet sproi

pilan trm model. Wit UL the front.I I i ftfan in the mid ] aLio irv shown in

Figure 5-26 as a fu'nction of deck pitch angle. Close to thle deck, liftL and

pitching moment vary sgi1 gn cifianl V Wi th t11e pi tch ang e , due to the stronger

fountain compared to the thiree-Jotcofgrain Pitch anleýJL has 1little

effect OGE. Similarly, induced lift and tligmoment~ vary sig~nificantly

With deck roll angle ICE, but not OGE', aq shown in, Figure 5-27.

[he induc.ed lift 1GiE, !;esentedlu in F'*.;Igre 5 -22, ýor the. twoC-noz~iz con-

figuration are similar to those for thle four-Jet configuration, even though

the four-jet configuration has a stronger lountain. lInrcrasing; the spacing

between the two nozzles increases thie induced lift by nea ri'. -2 percent. How-

ever, even OGE the induced lift is approximately 1.5 percent higher than for

thle three- and four-jet conlf igurations . A 30/50 thirust Split a~ppears to 1be

optimum as shown in Figure 5-29.

Induced lift and pitching moment of the two-jet model are sensitive to pitchl

angle near the deck, as shown in Figure 5-30. Induced lift and rolling moment

are less sensitive to deck roll angle G12 than onOttle four-jet configuration

but aire more sensitive than an thle three-Jet model as shou-n in Figure 5-31.

3.2 DYNA~IIC DECK tio'niN, EFFICTS - The primary objective Of this program. was

to investigate the effects of the heaving, pitching, and rolling mot'on of a

simulated landing platform onu the _iet-induced aerodynamr~ics of both SubIsonlic

and suuorsolli2 V'/STOL aircrafLt designs. Dynamic tests were performed With

simple one degIree.( ot I reedom notions, Suchi as lieave, and with comhined mo-

tions , such asý hiv nd roll1. The res;ponse of the aircra ft models to the

ccc

ALII

0 C:5

0 U.

Supersonic V:'STOL Pitch EffectsCotifigurdtion 35 4 Jet Mid Front Jets 0 0 00

-0 .04 -----.... .. ..

-008 ----.... .0 3.26 330

A8,16 327.............-. ... . ..... .... ----- ------

-0.12 ......------------ ....

.. ........ ... . .. ----- -- ---

- 0 .2 0 -- --- .... --------- I-- --.....- - - -- -

-0.24 ----- ----- ----------

-16 -8 0 8 16P,tcri Angle, e. y1ý

a) IflducE J Lift

FIGURE 5-264 JET SUPERSONIC V/STOL STATIC PITCH EFFECTS

Supersonic V/STOL -Pitch EffectsConfiguration 35 4 Jet Mid Front Jets -00 0'

0.12.. ...

0 .08 ..... ..... .. ...Hi-De Ru No.

ai 3

2 0.04

S

-0.04 ---- - -

-0 8 - - -- -----------

-08-

....... .....

-16 -8 0 8 16

Pitch Angle, u.- de~gGP8 '00695 2

b) Induced Pitching Moment

FIGURE 5-26 (Concluded)4 JET SUPERSONIC V.-'STOL STATIC PITCH EFFECTS

Supersonic VSTOL Roll EffectsConfigiur~itiot, 35 4 Jet Mid Front Jets 00 -00

0

-0048

H/Die Run No.

-0.20 ... 1. ..... .... ---- 63 1

468 8 1634R.l .A.. . . .. nq.. .. .i- --- .... .. . .. ... . .. .. .. ... .. .......

-0.24

-16 -8 8 16

Sup~ersonic V,'STOL Roll Effet tsConfiguration 35 4 Jet Mid Front Jets tU 00 00fJ

0006

H/D Ru~iNo.

S 3 0 260.004 -- -2 ---

A 8.16 .4

ir 0.002 - - -----

cc .... .. -- -- -- - --

-0.006 J

0 00 2~ --- --- 8- -- ----- -- -- -- 6... .. ---- -- -- ...

-~~~ ~ ~ ~ -- i -i -------------------- ...

b)~~--- ..d e Rol. Mo.n ........0.004 ~ ~ ~ IG R ----- 27 -(C -----lud ---d) -

4 JE SUERSNIC /STL SATICROL EFECT

.. .... .. ... - - -

FSuporsonic V/STOL Height Eflects

011

F0on ..... ... - .Configuration Axial Location Run No.

I . 38 Forward 350, 359,363 I I

*-t* a39 M~d 375,365,364

-0. 1. ..........

--0.4 -- 4.-

-. 0 4 8 12 16

FIGURE 5-28 er~~~~

2 JET SUPERSONIC V/STOL ST ATIC HEIGHT EFFECTS

911

i. . ... .........

..... . , .: *

•W .1.Si i

' 'r .

-- - w--O- -2 U

( F•...-'-3

, q. ' .. .. ... .. .. ..

I5 I t: /I 0 "

e.I II I

~0

-i L

z

I-

N LOC5

E;I/7r ji-I pazanpul

93 . * * '

II I • • • • • iI • • It ilI • • • • • • • 4t

Supersonic V/STOL -Pitch EffectsConfiguration 39 2 Jets Mid Front Jet NPR =1.5 )00 H/Dje 2.45 Run 378

0.02 *- .----

--0.04... .. . ...

-0.061 1-

-0.10

-16 -8 0 8 16

Pitch Angle, r deg

a) Induced LiftFIGURE 5-30

2 JET SUPERSONIC V/STOL STATIC PITCH EFFECTS

96h

Supersonic "/STOL - Pitch Effects

Configuration 39 2 Jets Mid Front Jet NPR =1.5 400 H/Dje =2.45 Run 378

.......... .....

0 .............--.. ..

.1.....

..{...........n -0.02 I~ ~i"

-0.03 --.-16 -8 0 8 16

Pitch Angle, a deg

b) Induced Pitching Moment 6P8-0895.I11

FIGURE 5.30 (CONCLUDED)2 JET SUPERSONIC V/STOL STATIC PITCH EFFECTS

V

Supersonic V/STQL - oll EffectsConfiguration 39 2 Jets Mid Front Jet NPR 1-5 ck 00

0.0

I0 1 - -- --- - -- -

... .. .. ... .

-0.0 16- 77I 1Os un

-0.2

-0124

-0.24

-16 -8 0 8 16Roll Angle, *,.deg

43P78.OI08H I I]

a) Induced Lift

FIGURE 5-312 JET SUPERSONIC V/STOL STATIC ROLL EFFECTS

98

deck motion was used LO te-'sL; 1sh t.Ie I reque'Icy conztent L iL tIil .01vda.1 inlid O.

p1) s 1 11 L iL0olIII i•) IL LwLefL1 LIi t:;oLion ItIId LI: rI iponsc. i t. : e I e( LS

8-elQo'ted Conif iguraL ioll ViarL tbles on the d',htý i,. 'usLh . "cL al].o iflvS-

t igat9, d . 'he dvn jinic it-i ndtedL forve ;nd ioome.inL dtiL:i ire p-t'd'llLtd i1

Lhe L" enL trotv ill :ondix C inl Vol HIeTI I of 01 0is reOorL.

5.2.1 Dvnarmic .eL-_TtIdu•L'd_ Force_ and M0omejnt D)aLta - Tests were performed

at scaled deck motion frequencies and amplitudes which bracketed values pre-

dicted from Reference 2. For example, for a DD963 class destroyer in a rough

sea the scaled frequency is about 1.5 Hz and the scaled amplitude is about

one equivalent nozzle diameter (about 7 ft or 2 .1ra full scale).

In this study, induced force and moment data were examined for five

second time segments randomly selected from the dynamic data records, which

were nominally two minutes in length to allow statistical analyses as

described in Section 5.2.2. As with the static hover data, discussed in

Section 5.], emphasis is placed on presenting induced lift. However, the

effects of the deck pitch and roll angles on the induced moment data as well

as the induced lift are presented. In addition, most of the data presented

are for the subsonic configuration.

Response to Deck Heave - The influence of deck heave on the induced lift

of the fully-contoured subsonic model is shown in Figure 5-32. The heave

amplitude ias 1.5 D. at 2 I!z, with the neutral point set at the height forIe

maximum induced lift (H/D. = 2). Thus, the height of Lhe model above the

deck varies sinusoidally from an H/D. o0 0.5 to 3.5. The induced liftje

response is of a complex periodic nature, but is fairly repeatable, consider-

ing the highly turbulent nature of the flowfield. It should be noted that

for each of the dynamic data presentations, the deck motion is shown properly

aligned with the aerodynamic response.

At a typical gear height, H/D. of 0.7, the lift loss is about 3 percentje

of the net thrust. As the deck moves away from the model, the induced lift

reaches a peak level near H/D. of 2.0 and then begins to decrease as H/D.Je je

approaches 3.5. However, when the deck approaches the model, peak lift is

higher at an H/D. of 2. This increase in lift (approximately 2 percent) isIe

attributed to a compression or increased cushioning effect in the fountain

region due to the velocity of the deck (approximately 6.3 fps or 1.9 rm/sec. max).

The inner region plate model described in Section 5.1.1 enables the

separate evaluation of the heaving motion on the fountain forces. In dynamic

tests with the inner region plate model, the same incremental increase in

the fountain force occurs with approaching deck motion as with the complete

100

-17-

04 \0

~ti.

uj >

oW 0

o

0i-o 0 - -- ~ 0

NU -J

D U.,

Z- 1~

In . ....

model . These results, shown in Figure 5-33, support the concl-icion that the

increased lift effect with approaching deck motion is associated primarily

With ti-e fountain.

The induced lift is influenced at certain heights to a slight degree by

the Crequenlcy of the deck miotionl, as seenl iln Fig{ure 5-34, whiere .lat-i are pre-

sented for both 1, 2, and 3 Hz. A larger difference is apparent at 3 Ilz be-

tween .he induced lift values for heave toward and away from Lhu modul. Tis

is attributed to the change in peak deck velocity and the modified compression

effect in the fountain.

The decrease in the induced lift variation with heave amplitude is shown

in Figure 5-35 for an H/I). of 2. The reduced response is apparent at a heaveje

amplitude of 0.5 D.je

Response to Deck Pitch and Roll - For small ships, the roll i.s generally

the motion having the highest frequency and amplitude, and thus, may have the

most impact on V/STOL aircraft operations. For example, the DD963 class ship

can respond to a rough sea condition with a roll of approximately +100 and

a full scale period cf about 8 seconds (Reference 2). The deck pitch is of

much smaller magnitude, generally around +20. However, for this study equal

pitch and roll amplitudes were investigated, since it was assumed that the

V/STOL aircraft could land or take-off at any orientation relatlve to the deck.

The induced lift and rolling moment variations for +20, +60, and +100

of deck roll are presented in Figures 5-36 and 5-37 f~r the subsonic config-

uration at an H/D of 2. A significant induced lift loss occurs for rollje

angles greater than +20. This is attributed to a loss in the fountain lift

as the impingement point moves off the centerline toward the side further

away from the deck and to the upward slope of the fuselage relative to the

deck. The lift loss is accompanied by a destabilizing rolling moment, which

is primarily caused by fountain impingement on the wing. With dynamic motion,

the impingement oscillates back and fortii from one wing to the other.

The effects of deck roll are highly sensitive to height as shown in

Figure 5-38, where the induced lift and rolling moment data are presented for

+100 roll at H/D, values of 0.8 and 5. Adverse effects are negligible at-- jean H/I). of 5.

JeThe induced lift and pitching moment variations for +_', +6', and +10'

of deck pitch are presented In Figures 5-39 and 5-40 at an I/D. of 2. ln-jo

duced lift losses arc apparent primarily at the pcitive, or nose up, pitch

102

I

ccU*

0v

H- - - -

oj 0

VC cc- -C0

C~%J w4r

00

zz

0 0 I ( l

LU-

-i 0

100

CONFIGURATION 1 H/DI= 2 h/Die = 15 o,=00 ) = 00

4 4

HEIGHT H2

H/Die ~'

fh =1 Hz 0 RUN 90.10.08 I

INDUCED 0.04 - 4LI FT KAv0

FG -0.04 -

-0.0-IiZ

4

HEIGHT2

fh 2 Hz 0 RUN 90.20.08 - - - -

INDUCED 0.04 4

LIFT_AL , • L • •T1 ( ! ! i l i IFI 004 II 1 [ l l I I I i I I(! ! l

-0.08~ __

4

HEIGHT

H/Die 2

fh 3 Hz 0- RUN 90.30.08

INDUCED 0.04 K i.2, 4"LIFT 0 All /A 'ol

FG -0.04

-0.08 -

TIME. t SEC

FIGURE 5-34

SUBSONICV STOL HEAVE FREQUENCY EFFECTS

CONFIGURATION 1 H/Die 2 fh = 2Hz u 00 ) =00

HEIGHT

H/De 2 H

h/Die =0.5 0 . SRUN 90.50.06

INDUCED 0.04 -----LIFT

0.02

FG 0

L.02

4

HEIGHT *.

2H/Dje

0.06 h/Dje = 1.0 0 RUN 90.4

INDUCED 0.04 "_LIFTA

ALA

0.02 x

FG 0v v

4

HEIGHT2

H/Die

h/Die = 1.5 01 RUN 90.2

INDUCED 0.04

LI FTr N l

FG -0.04 - ,-4:

-°°8 01 2 3 i ' 4 5TIME, t SEC ,, ,s_-t*

FIGURE 6-35

SUBSONIC V STOL HEAVE AMPLITUDE EFFECTS

105

CONFIGURATION 11 H/Die -2 f, 2 Hz =0

10 / ,F.

ROLL ANGLE-•0

DEG

+20 -10-- RUN 96.20.06•

INDUCED 0,04 - ilYLIFT

AL 0.02

-0.02 - -

10

ROLL ANGLE ADEG

-+ 60 RUNI 96.40.06 - -

INDUCED 0.04

LIFT 0.02 A A A, A A A A AFL 0.0 Ir tV r]v! Jv / Itv

-0.02

10.ROLL ANGLE,

-1 = 1

0.04 RUN 96.3

INDUCED 0.02 A h I A A - "

LIFT fl 1 111 11A11A 1AA11A-1- ' rL L nl U

FG -0.02

0 1 2 3 4 5TIME, t -SEC ,,,30,s ,,

FIGURE 5-36

SUBSONIC V/STOL INDUCED LIFT FOR ROLLING DECK

1I o6

CONFIGURATION 11 H/De 2 1, =2 Hz 00

10ROLL AvWGLE. 3I

DEG 0 RUN 96.20.06 -1 -- - -

INDUCED0.04ROLLING 0.02 -L

MOMENT

CRMS-0.02-- -

10ROLL ANGLE,

0DEG 0

-10, RUN 96.4

0.04 - -

INDUCEDROLLING 0.02 --

MOMENT

CRMS 0

-0.02

- 0 .0 4 . . _

10ROLL ANGLE,

DEG 01

-10 RUN 96.3

_0 .0 4 0 A I_ . . . . . . - -

INDUCEDROLLING 0.02 IN DCMOMENT

CRMS

-0.02f 10

-0.04 -

TIME, t- SEC

FIGURE 6-37SUBSONIC V/STOL INDUCED ROLLING MOMENT FOR ROLLING DECK

10/ -

CONFIGURATION 1 u= 00 lo o -+ 1 , = 2 Hz

ROLL ANGLE,

10

DEG = U.9.

H/Die = 0.8 -10 RUN 92.30.02

0 A - A- : A :: ._ it

INDUCED "FtF

LIFT -0.02tl

-0.04 -

-0.08 - -.- - -

ROLL ANGLE, i -

DEG 0 T-' ---

H/Die 5.0 -10 RUN 38,10.03

INDUCED 0.02LIFT

AL 0.01 vi~VFG 0

-0.01 '.0 2 3 5

TIME, t - SEC •*" "**

FIGURE 5-38SUBSONIC V,, STOL HEIGHT EFFECTS FOR ROLLING DECK

108

_ _ _ _ __ _ _ _ __ _ _'

AtLLILtides relative to tilL_ deck. This is attributed to increased suckdowl

nlea;r tile two rear nozzles and aft-end, which are nearer the deck at PosiLtlve

pitlch angles. ,

The induced pitching momellt tends to become more negative (nose down) with

n1, gatjire pi tclh angle, probably duec to an increase In suckdown on. the fore-

body and movement of the fountain Impingement point aft.

As with deck roll, the adverse effects of deck pitch are negligible at

an il/D. oI 5. This Is illustrated in Figure 5-41 where the induced lift and

pitching moment are presented for .+100 pitchat fl/I) values of 0.8, 2 and 5.

Based on the effects of deck pitch and roll discussed above, a pre-

ferred aircraft orientation, particularly during recovery operations, may be

derived. Since deck motion in the roll axis of the aircraft has more

impact on the lift and stability, alignment of the aircrafL roll axis

with the ship pitch axis wculd appear to be favorable due to thv lower

amplitude pitching motion of ships.

Response to Combined Motions - Tests were performed with various com-

binations of heave, pitch and roll motions to measure the jet-Induced aero-

dynamic response of the aircraft to the complex flowfields. established under

these conditions, The effect of the phaqe angle between the motions was

also Investigated (e.g., the roll and pitch motions were te.sted in phase 3nd

90' out of phase). Most of the tests were made on the subsonic configuration

at an IliD. of 2.

The lift response to combined heave and roll notions is presented In

Figure 5-42. The heave amplitude was 1.5D. and the roll amplitude +10', both

at 2 Hz. A lift loss of approximatelv 6 percent occurs near a tvplcal gear

height.

Responses to combined heave and pitch; pitch and roll; and heave, pitcli,

and roll are prFcnted in Figures 5-43 through 5-45 . Each .er of data

indicates a fairly well defined, repeatable, complex periodic response to the

combin d motion. Thus, the response to complex motions is not random, butfollows a consistent pattern.

Limited tests were performed with heaving motion superimposed on a height

vwriatlon to simulate vertical take-off and landing maneuvers. The height vai V.-iJ

tion (or variation of the deck neLutral point) was accomplished using a ramp unc-

tion generator for the height, plus a sine function generatLr for thc- heavet.

A partial trace of the induced 1 ift: rcsponse taken in ;j height range from Fit ).)e I

109

00 f~l

CONFIGURATION I H/Dje 2 f,, 2 Hz ).

10PITCH ANGLE. ,

DEG 0k±20 ~~-RUN 82.6

INDUCED -10ILIFT 0.06

I

ALS 0.02

AAFG vV "V: T"Vv -Y V " -

01

PITCH ANGLE.

cy 0DEG

"0.80 -10 RUN 82.50.06 ~- -•- --

INDUCED 0.04 A

LIFT

-L 0.02

00

-0.021 -

PITCH ANGLE,a0

= : _ .1000.06ck 1loo EG -oj vRUN 82.4

INDUCED 0.04 A AAk A

FG 0

-0.02 ..

0 1 2 3 4 5TIME, t SEC

FIGURE 5.39SUBSONIC V 'STOL INDUCED LIFT FOR PITCHING DECK

110

CONFIGURATION 1 H/Dje = 2.0 1, 2 Hz 00 , '10.

PITCH ANGLE,

t2° DEG 0-0.01 RUN 82.6

INDUCED -0.02 -0.

PITCH ING A' ik i'MOMENT -0.03 AA

CPMS q

10.PITCH ANGLE,

SDEG RUN 82.5

INDUCED -0-

PITCHING

CPMS -0.06 - - --

10

PITCH ANGLE,.

Lk = ±100 DEG0 -1 RUN 82.4

INDUCED -0.02

PITCHING 'MOMENT -0.04 - /"

CPMS _006W

0 2 3 4 5TIME. I -SEC . -

FIGURE 6-40SUBSONIC V STOL INDUCED PITCHING MOMENT FOR PITCHING DECK

]11

CONFIGURATION 1 loo.0 fc =2 Hz ~0 0

PITCH ANGLE, 10-

DEG 01 1-H/De .0.8 -10.-.

RUN 82.30.08--

INDUCED 0.04--LIFT

FG -0.04V

-0.08

PITCH ANGLE, 10

0k 0H/DIe = 2.0 DEG -10 -R 8

0.06 RUN 82.4006 - - - - --

INDUCED 0.04I-IFT

0,02

FG 0 fM

-0.02- - - - - - - - - -

PITCH ANGLE, 10 1f\

H/Die = 5.0 DEG -10 .L.-3.L RUN 85.30.03-

0.02-

INDUCED AI AA hLIFT 0.01-

FG V I

-0.01

-0.020 1 2 3 4 5

TIME, t - SEC

a) tnduced Lift

FIGURE 6-41SUBSONIC V STOL HEIGHT EFFECTS FOR PITCHING DECK

1T2

1CONFIGURATION 1 . 100 fa 2 Hz y 00

PITCH ANGLE. 10

DEG -10HID =0.8 RUN 82.3

INDUCED -0.02

MOMENT -0-.04 A

C -0.06 v - - -•

-0.08 -10

PITCH ANGLE.Q 0

H/De 2.0 DEG -10lI-iJ•-- RUN 82.40 A

INDUCED -0.02 - -

PITCHING JýMOMENT -0.04A

CPS -0.06

-0.08

PITCH ANGLE, 1

"~0H/Die 5.0 DEG -10- RUN 85.3

0

-0.01

INDUCEDPITCHING-0.02MOMENT -0.03 f

CPMS

-0.04

-0.05 j

012 3 4 5TIME t SEC 0 ,0.0 '1

b) Induced Pitching Moment

FIGURE 5-41 (Concluded)SUBSONIC V STOL HEIGHT EFFECTS FOR PITCHING DECK

pI'.

11 3

j

IIa

Lyj z+1 - >

Cc

o. 0c

0

114

A'

rww

ýa:UJ0

LL

o 6L

X0L

II <

LLL

II w

LL 0

CONFIGURATION 1 H/Die = 2 t - 100 100 f,.1 = 2 Hz RUN 165.1= 00

~ 10,

DEG .1L h L-10• .' ': ". ': .

-lo •

ROLL ANGLE, .j,

-f0

DEG +

-10

0.04--

0.02 -

0

INDUCEDA ALI FT -0.02

AL -0.04 11 u il V u

FG -0.06

-0.08

-0.100 2 3 4 5

TIME, t - SEC UP,6-0*95

FIGURE 5-44

SUBSONIC V/STOL INDUCED LIFT FOR PITCHING AND ROLLING DECK

116

CONFIGURATION 1 H/Dje =2 h/Die +1.0 "3-+100 ±=-100 RUN 171.1

fh, c 2 Hz

4

HEIGHT

HIDie 2H

PITCH ANGLE,

DEG VVV

-201-20 +c• ,

ROLL ANGLE, '(-

A ADEG 0

-20L' ----- : • ••

0.04 - -

0.02

INDUCEDLIFT -0.02 L

-00 1oo . Ail l Li A 1 lA I

-0.08

-0.10

0 1 2 3 4 5TIME, t SEC

FIGURE 5-45

SUBSONIC V/STOL INDUCED LIFT FORHEAVING, PITCHING, AND ROLLING DECK

•L7.

¶ • • =111 17

of 2 to 5 wt Ih a heave a nil) it tide o1I app roxinItLuL I y 1 .0 I). is shtownl in FiiturC2

5-46. The results simulate a vertLical landing a;t a descent rate of 0.06

fps (or 0.018 m/sec), whiich is c(nsiderabiv Iess t hA ;uct_,a dciceni rates

(about 3 fps or 0.9 m/sec). However, the restILs are more c(learly indicated

at this rateŽ. Data for higher rates are aliso ava;i lbtl( in AppelIdix C. 'he

induced lift variation shownr in Figure 5-46 indicates an increas.2 . in lift as

the deck height approaches an It/I). of 2, and is generallv consic:tent with

the data obtained for motions about fixed points.

Configuration Effects - The effects of overall aircraft design (subsonic

versus supersonic), nozzle arrangement, lift improvement devices, and fuselage

contouring were also examined, Induced lift data are presented for a heave

amplitude of 1.5 D. at an H/D. of 2. The effects of the selected configura-je .je

tion variables are generally consistent with those observed in the static

hover data at a given height.

The three-nozzle subsonic planform configuration is compared to the

three-nozzle supersonic planfona configuration in Figure 5-47. Substantiallv

different induced lift variations are apparent since the subsonic configura-

tion has a relatively strong fountain and low suckdown whereas the suckdown

dominates the supersonic configuration.

The effectiveness of the LID's in improving the lift characteristics of

the subsonic configuration IGE can be readily seen in Figure 5-49. The

maximum induced lift of approximately 12 percent is even larger than that

measured in static hover tests due to the increase in the cushioning effect

when the deck is approaching the model. The results for rolling motion in-

dicate that the LID's are effective even at high roll angles, consistent

with the static data results. These data are given in Appendix C.

The fuselage contouring effects on the induced lift can be readily seen

in Figure 5-49 for the subsonic configuration. The largest difference is

near the deck neutral point, H/D. of 2, and as explained in Section 5.1, isje

attributed to the difference in curvature in the region between the two rear

nozzles. This is the region of the strongest fountain momentum and the

resulting net lift on the fully-contoured model is reduced due to the upward

curvature of tile lower fuselage.

5.2.2 Frequency Content and Phase Relationship of the Dynamic Data -

The frequency content of the aerodynamic response to the deck motion was

assessed statistically 1v performing a power spectral densi ty analysis. Sinco

the induced forc.e and mor.(ent data were foun1d to be stochaS tic comple: periodic

118

(mD

0

> Lo -. ;

00

U. I

o~~~c - - -

LJ.0 .

- --q

limn?

4

5

0 ~N---- >

z~. 0.-cc .

>iik u UJ

zzIN

z00

-J 0 cc-< LL

wLL0 0L) 0

ci 0IULIL ) J1) I; L

t ,IJ

CiC

.j.

zJ

0 L7

-. ----- L

u - -

oj jII LL 1)U

12

H/Dje=2 h/Die = 1.5 fh =2Hz =00 00

4

HEIG HT 3 " -S2 _ 'HID HH/Dje 1

CONFIGURATION 1 FULLY-CONTOURED RUN 384.20.04 -oAo AI ! A! 4,1 nj A I . r

INDUCED 00

-L -0.02 !

-0.04

CONFIGURATION 14 SEMI.C4ONTOURED RUN 152.30.06-

AiINDUCED 00LIFT 0.02 .. . , -. . ,

-1L 0 2-

F . 0 i iv iij Wl ' i , .-

-0.04 tVLiJiA iCONFIGURATION 2 PLANFORM RUN 194.4

0.121

INDUCED 0.08 .

FG-0.04

_A

SUBSONIC-0.08 - -00 2 3 4 5

TIME, t SEC

FIGURE 6I-49,

SUBSONIC V/STOL FUSELAGE CONTOURING EFFECTS FOR HEAVING DECK

,2

!'

122

data and not non-stationary random data, suhstant ia liv I ss L!b!n thIe two

minutes of data acquired are actual ly necessary to issess the fr 'reniecy 'ontent .

The phase relationship or lag time between the input deck no! ion ;Jad thei

O at put aerodynami c response was oh• tai ned f rom tlIc cross power sple i• &I densiLy.

Limited auto correlations and cross correlations verified that tile major aero-

d.ynamic responses measured were of a periodic nature similar to the input

motion and that the responses correlated with the motion.

A power spectral density (PSI)) analysis of the indtuced lift data is pre-

sented in Figure 5-50, reflecting responses to heaving motion (amplitude of

1.5 ). ) with the neutral point at an Fl/D . of 2 on the fully contoured sub-

sonic model. The PSD indicates that the major response is at the frequency

of the deck motion, in this case 2 Hlz (about 0.1 Hz full scale). Lesser

responses are apparent lt multiples of this frequency.

PSI)'s for deck motion frequencies of 1 Ilz and 3 liz, shown in Figure 3-51,

indicate the same results. Depending on the shape of the lift loss curve and

the nrutral point setting, a response at higher frequencies can result from.

a given motion. For example, about a certain neutral point, a configuration

may have an induced lift variation with height which has a local maximum

point in addition to different end point values. For heaving motion, responses

will be at the primary frequen'..' (heave frequency) and also at twice the

primary frequency. Examination of lift loss characteristics measured at static

hover conditions verifies this observation.

The lower deck heave amplitudes at an t/D. of 2 result in less variation3Lin lift, as shown in Figure 5-52. Tntegration under the PSD curve provides

the root mean square value of the induced lift. Responses at ii.Ther frequencies.

are not as apparent as in Figure 5-50, due to the height range covered.

The phase relationships between the input motion and thu :espunses were

analyzed statistically using the imaginary portion of the cros:; power spectral

density (CSD) function, which is expressed in terms of phase angles. These

phase angles were correlated with aircraft height to illustratL tile change in

phase angle with distance, Results are shown in Figure 5-53.

As expected, the phase angle lags increasingly with the height above the

deck. The phase angles can be e:,pressed in terms of a lag time as well. The

results indicate essentially an instantaneous response to the deck motinn when

the model is near the deck. The slope of phase angle versus height remain.s

nearly constant for heaving motion with different confic-urations. H1owe ver,

CONFIGURATION 1 H/Dje=2.0 h/Die -±1.5 fh=2 Hz a =00 ) =00 RUN 90.2

4

HEIGHT_ _

2 _

INDUCED 0.04-LI FT

G *-0.084

0 12 3 4 5

TIME, t SEC

0.014

0.012 -

POWER 000t_SPECTRAL 0.008 ---- tDENSITY000- .-- 24(rms/Hz) 0.4

0.002--01

FREQUENCY, f -Hz pIcos5

FIGURE 5-50SUBSONIC V STOL INDUCED LIFT PSID RESPONSE TO HEAVING DECK

12 24

CONFIGURATION 1 H/DIe 2 h/De 11.5 fh 1Hz c0 00 =00 RUN 90.1

4-

HEIGHT xr

H/Die I H

0.8 -

INDUCED 0.4

LIFT

2aL 0

"FG -0.4

-0.8 •- .0 1 2 3 4 5

TIME, t SEC

0.016 - --- - -

0.014- - -- - - - -

0.012 -

POWE R 0.010- - ---

SPECTRALDENSITY 0.008 ItN

Gx (f)(rms/Hz) 0.006 .. ... -

0.004- - - -- - - -

0.002 __ i00.1 1 10

FREQUENCY, f- Hz 0#,5-5-

a) fh = 1 Hz

FIGURE 5-61SUBSONIC V.'STOL INDUCED LIFT PSD RESPONSE WITH FREQUENCY VARIATIONS

125

CONFIGURATION 1 H/Die 2 h/Die = ±1.5 fh = 3 Hz 00 00 RUN 90.3

4

H/Dje 2H

0.08 -

INDUCED 0.04LIFT

L 0L'FG -0.04

-0.080 1 2 3 4 5

TIME, t -SEC

0.020 I

0.018 -

0.016 _

0.014 -

POWER 0.012SPECTRALDENSITY 0.010

Gx(f)(rms/Hz) 0.008

0.006 -

0.004 -

0.002k -___

0'0.1 1 10

FREQUENCY, f - Hz

b) Fh = 3 Hz off$$.

FIGURE 6-51 (Concluded)SUBSONIC V/STOL INDUCED LIFT PSD RESPONSE WITH FREQUENCY VARIATIONS

126

3

-1CONFIGURATION 1 H/Die 2 h/DiD 0.5 fh =2Hz L =00 =00 RUN 90.5

4

HEIGHT2-H/Die 2

0

0.06 -

INDUCEDA.MA

- iLTG 0.0

-0 ,040 2 3 4

TIME, t SEC

5.0

4.5 - _

4.0 - - -

3.5 -

POWERSPECTRAL 3.0 - --

DENSITY S2.5 . -- ,

Gx (f)xr10- 4 2.0-

1.5 - -

1.0 . ...

0.5 - , - -

0 . ...... L0.1 1 10

FREQUENCY, f- Hz

a) h, Oje a 0 5 oI

FIGURE 5-52SUBSONIC V/STOL INDUCED LIFT PSD RESPONSE WITH AMPLITUDE VARIATIONS

127

CONFIGURATION 1 H/Die 2 h/Dje = 1.0 fh 2 Hz u =00 0 =00 RUN 90.4

4

HEIGHT

H/Die

0

0.06--

INDUCED0.04

FGLIT 0.02 . . . . .

-0.02

TIME, t - SEC

1.8-

1.6- -- - -

"1.4 - --

POWER 1.2SPECTRALDENSITY 1.0 - . -

GK(f) 0.8 -

\Hz 0.

0.4

0.2

0 - - - - - - -0.1 1 10

FREOUENCY, f• Hz ,p

b) h, Dje = 1 0

FIGURE 5-52 (Concluded)SUBSONIC V/STOL INDUCED LIFT PSD RESPONSE WITH AMPLITUDE VARIATIONS

128

Z C) m. .. .... ;-7 ...0

I.;:1::: 00 OD 0 ry......21:: ;::! :3 D 0 ; L

.. ... ... ....

... . .. ... .

H 2.

wWw

0 0 , AL.. ... .- .. .. . ..0 9 i a .. ...

Qc.~ ~ ... .... .... w........ ~ .. . ...

configuration dependence is seen for deck rolling motion at different heights,

as shown in Figure 5-54,

To further examine the frequency content and phase relatilonfhip j)f the

data, classical linear frequency-response methods were applied. Th CLeck

frequencies were varied from 1 to 3 Hz at several heights for sinusoidal

heaving motions representing full scale periods of about 6 to 20 seconds.

The resulting amplitudes and phase angles of the induced aerodynamic response

are presented for the subsonic configuration in Fig-ire 5-55 in a conventional

Bode diagram format. The ratio of response to deck motion, given in decibels,

has a constant gain factor as shown by the data. The phase angle, given in

degrees, changes only slightly over the frequency range Indicating a trans-

portation lag.

The transfer function of the aerodynamically coupled system is nearly

constant, thus Indicating that this is a simple proportional system and that

varying the frequency from I to 3 Hz has little effect on the response. It

should be noted, however, that the transfer function is generated from a

statistical value of the response, and thus may not reflect frequency effects

at certain instances in time. This would include the frequency effect

observed due to heave in Figure 5-34. The gain factor for the amplitude does

change with height (Figure 5-55) and is configuration dependent. Similar

results also apply to deck rolling motions as shown in Figure 5-56 for the

supersonic V/STOL configuration.

It should be noted that tLe frequencies tested are relatively low, and

that an amplitude roll off could be expected at higher frequencies, but such

frequencies would be well beyond the range of realistic ship motions.

5.3 EiPIRICAL PREDICTION PROCEDURES - An objective of this program was to

develop empirical procedures for the prediction of the induced force and

moment variations with deck motion. Past efforts, both analytical and experi-

mental, have been directeu toward development of procedures for static hover

conditions. One such analytical study, performed under contract to N.ADC by

NCAIR, involved the development of methodology for the predictien of the jet-

induced aerodynamics of multi-jet V/STOL aircraft both in and out of ground

effect. The results of this program are reported in Reference 4. Currently,

the methodology provides reasonable results for the sockdown forces but the

fcuntain imp;ingemeit model overpredicts the resultant lift force.

730

m I

... ... ... ...0 L LLoc --

Z L .. ....j

W4 .. ....I..... ......... -..

- - 0

0) N Vt (a 00,.. .

Ec ... ... ... .

: ::!15 ;:: - 22 . :2::: ::; 4:. ::::

.. ... ..................

no .. ...

0 £ a.. ... 0....

.... ~DO .... .aw.i..i

.131....

I11

SubsnicVISOL -Coniguatin 1 eavng eckTranferFuntioLl 00 0

E 00

0) T 0 . 0 1.DE h 0.E Run .No .. .i" f ..... 11. Io.8 0.3 89.1 89.3 A

20 I-80

.. .. ..L.C00 Ci

'S 0

-JI -Phase I0 SCJ-20 C ST-

TT i: 17-

24 4 -41 0

Frequecy ~.. rad ..........- &

FIUR 55

AMPLITUDE ~ ~ ~ ~ ~ ~ ~ ~~ 7:; AN7HS NL RQEC RSOS OHAIGDC

-. 60 s

2 4 6 10-2

FeunyL.: - r e

Configuration 3 Supersonic V/STOL - Rolling Deck Transfer Function

!, ±100 a0o

100 -- * --- 200

..... .• ..... ... . ............. i.i ":i" ...!'.'":' "! :::) i .ii ':.A m plitude[i i.... . .. : .. ' . ..". ' i : ';T.i. ... ': 1 •

5" H/Die Run No. ___'"•_,___:____,__.._ ;

1.3 230

40 .. 23 4,_ _

OU 7 80

- - ......... . . ; . - . .- . : '

S. i . . . . . . . . ; ..... I . . . . : . . . . ! .~ ~..... ........;"!........ •.'.'....... ';. - . - • - ' : " i - - ' '! . .

S. ............ ... ........:. .... . . ..

Cr2 0

Q`

-Y" , : i .- • : i ' -' Phase • .O

0 ... ... 0

- 2 4 6 8 10 20Frequency, • rad.sec GO?$ 0 s55

FIGURE 5-56

AMPLITUDE AND PHASE ANGLE FREQUENCY RESPONSE TO ROLLING DECK

33|

A sign ificant qulant ity of empi r I cal I nformat ion was rt-qu i red L do veleolUl

the Refereonce 4 methodology, part iculnary relati e t te t Olt hent rainment of the,

Jet s and the tountain formation. Areas where addition A data are needed to

improVe the procedures are indicated in Reference 4. It is further noted tha.t

the comprehlensive theoretical prediction of the complex. flowfiel ds and the

resulting induced aerodynamic forces for lrbil.rrary V/STIO. configurations is

several ve~irs off, even for static hover conditions. Such a method would be

invaluable as a screening tool and efforts are continuing in this area at

MCAIR under both contracted and company funded programs, However, complemen-

tary efforts, relying more heavily on experimental induced aerodynamic data

are necessary at this time to develop rapid prediction procedures for static

hover conditions and to address additional factors such a• the effects of deck

motion, wind, and superstructure. This program supplied substantial data for

both static hover conditions and deck motion.

5.3.1 Prediction of Deck Motion Effects from Static ltover Data - The

parametric induced aerodynamic data given in Section 5.1 provide the capa-

bility of predicting the induced forces and moments acting on configurations

similar to those investigated for static hover conditions. The data can be

used to predict the effects of hefight, pitcih, and roll, nozzle arrangement and

spacing, LID's, and many other V/STOL aircraft design variables applicable

to both subsonic and supersonic configurations. Further, the static data

can be used to predict the induced aerodvnamic response to deck motions b%,

assuming that the motion is quasi-steady state. This can be accomplished

for a given deck motion, which may be .,omplex periodic in nature, by deter-

mining the deck height, pitch, or roll angle variation with tim..e and obtain-

ing from the static hover data, the corresponding variation in the induced

aerodynamic characteristics of interest.

Since the deck motion was well defined in this program, tLme attitude or

position of the deck at any particular time can be determined. Thus, the

motion can be defined by a series of discrete points. The induced force and

moment variations can then be evaluatied from plots of the static hover data.

Comparisons of the induced lift were made for ihaave, pitch, and roll at a

neutral point,.1!D of 2, for both the subsonic and supersonic configurations.

Tn addition, comparisons were made of tht, induced rolling and pitching

moments for the angular deck mot ions.

134

' I I I I I I

Based on the static hover data obtained, it was also pos;sible to generatL,

comparative predictions for some of the combined motion,;. These cumparistnflS

were made for combined heave and roll and combined p itch and roll both in

1ikise .n1d out of phase. The combined motions partit iularly indicrate soUIC,

rather significant differences from the static predict ions.

_ILLe, PiLtChI and Roll - Subsonic V/STUL Configuration - The comparison

Of L.,,' sLatic hover prediction with dynamic data for heaving motion is pru-

:elnted in tile time domain in Figure 5-57. The results are in fair agreement,

with the exception of the increased fountain cushion effect which ocu.urs as

the deck approaches the model from the maximum height of 3.5 D. . The dii fer-

once is more clearly show-n by presenting the comparison as a function of

height as in Figure 5-5J. This comparison was :.. e by fairing a curve

through a series of discrete points selected from the time history.

The static to dynamic comparison for the induced lift variation with

deck pitch is shown in Figure 5-59. Fairly good agreement is indicated, but

an increase in lifL from the fountain (approximately 1 percent) with dynamic

deck motion is apparent. This is attributed to the increased cushioring

effect in the fountain due to the deck pitching motion.

in Figure 5-60, a fairly large difference is seen between the static

prediction and the dynamic data fc induced pitching moment, the dynamic data

indicating a more negative or nose dow•n pitching moment. ie negative pitch-

ing moment with positive pitch (nose-up relative to the dvck) is attributed

in part to an increase in the fountain impingement force between the two

rear nozzles due to the compression effect. This has been shown to be the

region of highest fountain strength in Reference 3 and is aft- of the c.g.,

thus the force on this region p'covides a negative pitching moment contribut ion.

This overcomes the positive pitching moment contribution caused 1,N the in-

crease in suckdown on the aft fuselage. The negative pitching moment with

negative pitch (nose-down relative to the deck) i:- attributed primarily to

rmove~ment of the fountain further aft of the c.g. than occurs at fixed deck

pitch angles.

The static Co dynamic comparison for deck roll is shown in Figure 5-i1.

As with pitch angle, the dynamic induced lift variation is approxim,,telv I

percent higher. The induced rolling moment variation Is A•lso shown in .iý:,irc

5-(,]. The dynamic data are not symmetric about the zero level, as is tihe

s-tatic hover prediction. This may have been due to a slight offset (ah, t

0. )') in the angle, since the rolling moment is very sensitive to roll

On. ;u neir zero degrees (see Figure 5-3b).

13)

II

000

zzw >

LL -J i c

LL U) - - 0

04

clyl

Ne 0

w 0 A# 0

Jib

*. ._.. .. ....

CC

o ........

*o 0

. .. ....

- ~ ~ L -t-.-----& ~o

DJ1NI ;7Inu

137.

zz4 ~0.

N I-.

o LU

U. C L,)Z

LjS2 x-~W -ciZ-- U

01 a 00

C.)* *-=* z LL.

0

ova.

4

0 0 0 o

0Lýj U.

z 0

004 I-

0 J

z z

> --

0 oWI- I--

V co 0

00

4 139

u-j

>I

a: 2

to Q

N 1W>

LL. 0LL U. W

cc a: -

II ~ 0

Li. Z

o Im

IbII

lleave, P1itch, and Roll - Supersonic V/STOI. Coniiguraf ino - The criparison.

of th ULstatic predict ion and t01 dVnuri I data for hewaving motion 15 .sihown in

Figure 5-62. The induced lift is dominacted by a large stickdown. Al though the

minimum induced lift levels compare well at an h1/D) of about 0.8, the

dynamic data reflect a lift loss significantly higher than the predict ions

(as Much as 8 percent) at I1/1). valties above 1,6. This is attributed to an ir-j C

crease in su, kdown effect resutlting from the rapid movement of the deck away

from the model. This adverse effect L, noL apparent on the subsoniic config-

uration, probably due to its rather low suckdown and strong fountain. Since

there is consistent evidence that there is an increase in the fountain lift

with deck.motion toward the model, it is logical to expect that there will

he some decrease in lift when the deck moves away from the model, particillarly

when the suckdown dominates the induced lift. -lThe static to dynamic comparison for the induced lift variation with deck

pitch is showrn in Figur,. 5-63. The induced lift variation is more noticeable

in the dynamic data than in the static hover data. Like..,ise, the pitching

moment variation increased with deck motion as shown in Figure 5-64. As

observed on the subsonic V'/STOL model, the induced lift is higher and if;

accompanied by an increase in the nose down pitching moment. The change in

pitching moment with deck motion is attributed to the same reasons as dis-

Cubsed for the subsonic model. jThe static to dynamic comparison with deck roll is shown in Figure 5-65,

As with the heaving motion, the deck rolling motion has an adverse effect

on the induced lift. An adverse effect on the induced rolling moment also

occurs, as indicated in Figure 5-65.

Combined Motions - Actual sea state conditions, being of a complex periodic

nature, cause a complex response fro, ships, as indicated in Reference 2. To .4I

evaluate the effects on induced lift, several combinations of heave, pitch, and

roll motions were investigated, primarily with the subsonic configurotion.

Predictions of the induced forces and moments could be made for some cases.

The compiarison for a combination of heave and roll is shown in hligurc

5-66 for an 1l/1), of 2. The static hover prediction was obtained fr )rim a para-je

metric plot of induced lift as a function of roll angle for scvcrtl ihtic;igim

(Figure 5-3a) . For discrete roll anglce:., the induced lift was dlet ertnined 1)v%

interpolation. It can be seen that the actual induced I -L' with I ,OnbilUd

motion was lower than predicted. Thc extremely complex, tc',-buleIIt lwt)w iciI

created under such combined motions is belicvud to increaie Lhe mi+ing and

entrainment and therefore, increase the I ift loss. For this case, LiLe' hiei've

1 1

00 0

ri

w4

-r LU

4L IX

Ln LL; m w

I-)

N 00

00

U..

zC

U.L

Co ~ N

0 cc

4 U

2 Iii

U- 4

x f 0 B-J

0~~ 0 .)

La u. 0

z0 0LLLn;

CY 0

0 0

o~U - -I

143

+ C)+1tN

LL CL 0I-a- 00

4L U> zL

160

zoo 0

UU

cc -f-. c

Z I i a

IIL Iu 1040D -2

C)

7510

00

0 wi

>- -

LL. 0

uJL

0

co V c

e - NJ 0 ) -

z - J 0"Z

06 j 2 cc0 ~~001-(I

2!c

CONFIGURATION 1 H/Dje =2 h/Die 1.0 1 =2Hz a=o0° - = .10° =00 RUN 172.2

4

HEIGHT 3 HEAVEH je 2 h ":j $._

2 0 H

ROLL ANGLE, 10 DECK .......

"0 A A ROLL

DEG -10 +

-20 _ _ _ _-_ _"_---_-"

00VARIATION DERIVED FROM STATIC HOVER DATA0.02

INDUCED , T / / ; .DYNAMIC DATALIFT -0.02 AI AA

-1L -0.04 M Al 1"

-0.06 Z •

-0.08- - - -- - -

0.006 , - -

-=+ 10° >-DYNAMIC DATA

0.004f

INDUCED 0.002 Mir AROLLINGMOMENT 0

CRMS-0.002

-0.004 100RVE F2.lY2ROMTAS1CDATA.0 2 3 4 5

TIME, t- SEC op,.0f, ,,

FIGURE 5-66SUBSONIC V/STOL STATIC TO DYNAMIC INDUCED LIFT AND INDUCED ROLLING MOMENT

DATA COMPARISON FOR HEAVING AND ROLLING DECK

and the roll were in phase such that the deck motion resembled a swinging

door. To supplement -the induced lift comparison, a comparison of rolling

moments is also shown in Figure 5-66. A fairIv g,iod t,,parisn is seun.

The static to dynamic comparison for a combination of deck pitch and roll

in phase is given in Figure 5-67. In this case, the deck rocks diagonally

from corner to corner and the values of the pitch and roll angles are equal

at all times. Static tests were performed by setting the deck pitch and roll

angles at equivalent values. As with the combined heave and roll motions,

the combined pitch and roll. motions have a more adverse effect on the induced

lift than indicated by the static hover data.

Tests were also made with the pitch and roll angles 900 Out of phase,

thus giving the deck a wobhling motion. For this motion, the vaJutes of the

piLch and roll angles are aLways different, but when either the pitch or ro:ll

angle is a maximum,, the other angle is zero. Thus, an induced lift predi,:t .on

can be made by using the static data obtained at the maximum values of both

pitch and roll. As shown in Figure 5-63, the dynamic induced lift is sub-

stantially lower than the static prediction. These results further sub-

stantiate the adverse effects caused by the increased turbulent mixing action

during combined motions.

To summarize the above comparisons of the dynamic and static data, it

appears that predictions based on the static hover data can indicate the

general trends of the dynamic response to deck motion and would probably be

adequate for trade studies early in the design. However, the static htover

predictions are often optimistic, particularly for the more complex combined

deck motions. Consequently, the static hover data do not provide the degree

of accuracy desired for aircraft design development.

5.3.2 Prediction Procedures for the Three Jet Subsonic Configuration -

The development of generalized prediction procedures of the jet-induced aero-

dynamics, even for static hover conditions, is complicated by the high degree

of configuration dependence which has been observed in this and many other

programs. Due to this strong configuration dependence and the many signi-

ficant test variables (i.e. height, roll, aircraft position relative to the

deck, etc.), the development of a generalized procedure for the prediction

of the effects of deck motion is believed to require additional. data at

147

dIC

4 -- -

4E

~~ju

> U'C4 I

w

z FLw00

0I 0

U. .~

o .o

N 0-

0~~ ~ 0 000

I I -

0 W w

-. 0

+1if

(NL N -C

0 M.

0

- - U.

q: I. co L 0ZoU

zj

A 0

LU U.:q N 0 (~ L

U LL.U

cr..

more ampli1tudes, f requenc ies and neutralI po i it t:e L i rigs as- wt, a." -re

Cundamental data (.See SeCtionl 5.3.A). H~owever, ba.sed tin tilt dvinamic dat I

obtained for tile full v-contourefd subsonic model , exp ress ions of thle Induced

aerodynamics have been devuloped for sel ected dccLk meot ions.

iince ( hie induced av rodvynain.l c respons'ýs t o deck mot ion are --nuru1ly ofi

a complex periodic nature, a potential expression for the variations Involves

aI Fourier series. For examp~le, tile induced I i ft express ion woujld ho Af the(

form:

k.~cs2n Trt + 2n iit

ýLF A+ ACs T +Bsn T

wheres numb tere fund amental period, n it; thle component frequency, K is tile high-

est umbredCoeffiCienlt selected, and A and B are the Fourier series cnef-n n

ficients.

As indicated by thle power spectral densities in Section 5.2.2, the in-

duced aerodynamic -e ýses to deck motion generally occur at tile frequency

of the morion and r-u].Eiples of this frequency. Use of a Fourier series

would i~nclude ter!-., -)r these frequency components.

Fourier Eeries curve fits for the induced lift variation with a heave

amptitude ot U.5 D, at ýan Hi/I. of 0.8 and cf 1.5 D. at an HID. of 2 ar,je Je lee3

given in Figure 5-69. An accurate fit of thLe dynamic data is apparent in bothI

Cases . The Fourier series exprossions include only those terms corretiponding

to the frequencies of thle response indicated by the PSL)'s. In addition, thle

relative value of each term is proportional to thle respective apl itude in

the PSI), indicating that the Fourier series reflects the correct power at

each frequency.

Fourier series curve fits arc shown in, Filcurers 5-70 and 5-71 for1 the

induced lift and pitching moment vaIriat'ions With. pitch angle at H'ID valIue s

of 0.8 and 2.0. Similar curves are provided in Figures 5-72 and 3-73 for

thle induced lift and rolling moment voriations with roll angle. Additional

pints are provided in Figuire 5-7'. for freque~ncies of 1 and 3 Hz. CGood fits

of thle data are seen in eacht case, using the termis in the Fuurier series

hlich correspond to the response frequencies indicated in thle PI'

CorretatiOnls were made of the Yourier series coefficients with the

zar-pi itudes and freqiuencies cf Ole motions. However, these correlations we rt

not well behaved either due to the hlighly turbulent nature of the plienomnena -4

or))oi * ...............................

00

.2 >

m

Q a a C

zi

-- -- - -- - -f

- -- - -- ----- ----

-- ------ li

-A -~- -- 0--------

C-4.... .. .. U.- -------

IIn

+1 >

c~~ ----

UL

0 4 U..L . . ..... .. . ..L

it It

CN

1l -i wl wa).

------ -----

00

o L

40 m

-- -- - -- -

II A

41 CO. .

C; .! - C

00

0

0~ I

S.. ..... . .

. . . o . ../ . -, U• : ,0- -------- L.

N -, . , . .r 0

zD

LA-

E C; * 6

j-,1 p 1-j paonpul

0 * .10 0

51

.4',L

IN-

olt

o1 ,.0

es C-

CO Im -- -ý -- - ý- -- -- -- - -_ --- -- ---

-o . ,

C,- ~ U t

+1 . 0 2

I I W

C-

~~~c d,~ .. -I

-3 5

co

----- -------. -- -- .. . ; . .. c . . . . . . . .. .... .z

S....-;.... 1 ... . . . . . ..... i....- .... ,................. . . 0

00

.. ... . . - ..... .

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z _ .• ,. , . . . .. :

IIL

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- LA)

d Ii 0

SV~dO luaw~oIN kI•L4311d pa:)npul

6 0

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c; z

0~~0 0r - -- - - - - -- - -- - - -

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Uj Lz 75

o 0 5c.. ....... L

U. ~ --- - - -

c~

C! 0

lj~l p:)npz

.1. 157

w : .. .

~~~~~~- -----, --- ---.. -.. ... . .cw

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---- - -- A- -z-- . . . . . . . . . . .. - .... . . . o ,

- --------. .'- •• :•• • . !i.: .

Cl)l

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o w m . . .. . w

_I ---- -- ..-... *. ; ...

0 . 0 0 -

.- . , -

6 C: 6 ci 6 6 CS0. T D.

"4 ( . :. I 0 0>S. . .. . "' : •.. .. . .. -- : - : - i:- .. .. C'- ! . . .-

CC

cli CN

-. I• j -p npul

158w

L+,

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0• 0

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- - - - -- . ... .I

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--- - , -

o.::. .. N 0

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S! • . ..i i- • . .. -fi . . ,-)+... . . . m -,= _ - , . "0

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C 0

S~yU) - uauoN Bill8 penpu

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--. - ----- --- .. .. ..... . . . ! • -

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-- --- --- .Aý_ --. :- .. .. . . ,- .- - ... .. -.. . N .. ... o,.

- -. . . . . . .- ----- --

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-- ~~: c • o o Co --.

44I--

: i -i . 0

.- c

- ij, -iuw V *1l8p:nu

160,

6 U

. . . .. , . .

• ..:,0

co I

II nI "* "

S- ...... .

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- a . .........

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-- . 0. ..

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" -- C .. . . . . . .. ... . .

c.r0)

.. -- .... . >

C)C

II I

¢5L o5ooo m ¢

i. i

C)

'. 117 paonpul

]6LU

o .. ... .. . . .. .. .. . . .

oc.i .- .... .. .z.. .

00

0 ~

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*~II 0 *0

---------. .

40 Lk0

- 0

-2 - -- ---

U.,

LU

00

0 0 0 0.

16b2

0- 0

. I.

0 m~ -0.

0o 0C .

0U

LLU

0 . . .

0

00

0 D

I ILU

00

0L .

NZ

.. ..............II-

.. .. .. .

D -1

I I . - .

0 L.

.L Lf. . . -

w 0•

LU U

-J. .. . . . ,

cc

- -... ... .

-LL

- -- -- - --

oN u.40 13

.. . .. . . . .. U .

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0 C)

00

144

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oz 4, 4cc, IN

AL C >* it 17~-J ~ C

u-

< wiu

C0 00 0o

o 0 0 0 0D

or the inability to adequatelv dofine the correlation. It i bhI i uVd t hat

data at moie amplit udes , freqti1nc 1V , and ne ut ral point s(t L ings woul d pro-

vide consistent correlations and thus, would allow the definition of the

dynamic response to any gi',en amplitude of motion. Potentital applicaieO loins

for these formrul ations oft Lie dynamic responses to deck motion for a repre-

sentative V/STOL configuration are in the hover control system design and in

piltoted computer-based simulations of the take-off and recovery operItions

aboard ship.

5.3.3 Suggested Approach to the Development of improved Prediction

Procedures - One area requiring improvement in the above approach, as far as

general applicability, is to relate the Fourier expressions to the significant

configuration variables such as the nozzle spacing, the inner region area,

and the total planform area. A more fundamental, less configuration dependent

experimental program would supply much needed additional information relating

to the separate effects of the important configuration variables and test

conditions on the fountain and suckdown forces.

In the Reference 4 study, it was concluded that the fountain flowfield

is an area that requires much further investigation to improve the resultant

force and moment predictions IGE at static hover conditions. In addition,

it has been shown in this program that the fountain may well have the largest

impact on the induced force and moment variations with deck motion.

The predominant impact of the fountain can be demonstrated by combining

the dynamic lift variation measured on the inner region plaze model (repre-

senting the inner region of the subsonic model) with the suckdown prediction

based on static hover data described in Section 5.1. Reasonably good agree-

ment between this induced lift variation and the dynamic data for the complete

model is shown in Figure 5-75 for heaving deck motion.

A similar procedure was applied to the induced lift variation with roll

angle, again combining the dynamic data from the inner region model with the

suckdown variation with roll angle predicted from static hover data. Again,

fairly good agreement with the dynamic data for the complete model can be

seen in Figure 5-76.

These comparisons imply that the jet-ind,,ced aerodynamic variations which

occur with deck motion primarily result from the modified founLain cushion

effect and the fountain movement with aný,ular motions. Thus, a parametric

test program uitilizing 2, 3, and , rozzle arrangements withli corresponding

1 66

cr. 0

Cu

4-4r

-, .

- II

?- i'z- <- oE I-~-

N V co

I-..-i7 lop-- - - ------

F/

Inner Region Model Fully-Contoured ModelH!Dje= 2.0 a =00 -- 100 f. = 2Hz

Preditcion based on rlnr region model divnamic (ddtd

Dynamic dati iConfigujraion 1 - Run 681

0.04

U-

S1___.

,/

-0.02

0 0.1 0.2 0.3 0.4 0.5

Time, t - sec 0p7I.O895-7,

FIGURE 5-76

INDUCED LIFT VARIATION FOR ROLLING DECK BASED ON INNER REGION MODEL

inner region plate models would supply significant information to relate the

dynamic force and moment variations with the important configuration vari-

ables. By limiting the investigation to the inner region, a truly parametric

test can be performed without being unduly restricted by the aircraft plan-

form shape. A corresponding investigation on suckdown would also be bene-Ficial by determining the conditions for which dynamic deck motion affects

suckdown.

Th.se suggested experimental efforts, combined with the results of this

program, would provide the parametric data base to allow the formulation of

generalized empirical procedures for predicting the jet-induced force and

moment variations with deck motion. Particular emphasis should be placed on

combined motions, which would normally exist aboard ship.

1Ii

A

16cI

6. CONCLUSIONS AND RECOMhENDATIONS

Several significant conclusions ..ere derived from this program regarding

the propulsive lift system induced aerodynamics of V/STOI. aircraft at both

static hover conditions and with deck motion. These conclusions are given

below along with recommendations for future studies.

6.1 CONCLUSIONS - The conclusions relate to tho effects of model tonfigura-

tion variables and deck motion.

Planform Configuration

o The three-jet subsonic configuration has significantly lower induced

lift loss than the three-jet su:,c -ic configuration primarily due

to a lower planform to jet area 10"io and a stronger fountain.

o The induced aerodynamics of a configuration having a strong

fountain are sensitive to deck pitch and roll in ground effect (IGE).

Nozzle Arrangement

"o Increasing the number and the fore to aft spacing of nozzlefs increases

the fountain strength and reduces the net lift loss.

"o Locating the nozzles close to the planform edge or in a region where

the adjacent planform area is small, reduces suckdoiwn.

Nozzle Simulation/Operation

"o Nozzle vectoring vanes and other f]jw control devices can increase

suckdon, and reduce the fountain strength which is attributed to a

more rapid free jet decay rate.

"o Testing at the full scale nozzle pressure ratii is required to pro-

vide the most accurate flowfield simulation.

"o The induced aerodynamics are very sensitive to the thrust bias

between the fore and aft nozzles.

Airframe Simulation

o Simulation of the model lower surface contouring, particularly in

the fountain impingement region, can significantly affect the induced

aerodynamics IGE.

o Upper surface contouring appears to be unimportant without crosswind,

but placement of the airframe surfaces in the proper plane relative to

the nozzlcs is advisable.

170

a Simple flat plate planform models provide reasonable data trends

and incremental configuration effects, and thus C:an be used for

economical preliminary configuration stodies.

o Near typical gear heights, the induced lift increases with wing

height.

Lift Improvement Devices (LID's)

o Properly designed LID's can significantly enhance the induced

lift IGE and can be effective even at high roll angles

Deck Size

o The deck size has no appreciable effect provided the model is centered

over the deck and no 5.uperstructure is present.

Deck Motion

"o The responses of the induced aerodynamics to duck motion arc of a

complex periodic nature at the same and/or multiples of the deck

motion frequency.

"o The responses are essentially instantaneous [GE due to the high

velocity jets.

"o Up to 3 Hz, the motion frequency has little effect on the statisti-

cal respon3e as indicated by a nearly cun6tunt transfer function.

However, frequency can affect the instantaneous response character-

istics.

"o The induced lift resulting from fountain impingement increases as

the deck heaves toward the model.

"o For a configuration with high suckdown, a significantly higher lift

loss occurs when the deck h2aves away from the model.

"o Deck roll produces a destabilizing rolling moment due to the move-

ment of the fountain.

"o Based on tests with an inner region model, the fountain appears to

have the largest impact on the force and moment varJations with deck

mot ion.

Prediction Procedures

o Predictions based on static hover data can differ signifir'antlv from

actual dynamic data and often indicate lower lift loss and higher

moment variations, particularly for combined motions.

,-''r - ----- T -- •- .... i..... ' ... -''i-... .. . r i. .. i~ ..... i -+ T i .. ... i7 " -°f.1.71 . .

o The differences between the static predictions and the dynamic

data are attributed primarily to increased turbulent mixing and

modification of the fountain impingement forces due to deck motion.

o The induced acrodvnamic variations can be accurately expressed with

Fourier series.

6.2 RECOMMENDATIONS - Based on the results of this program, the following

recommendations are given to guide future efforts.

"o In the near term, further detailed analyses of the established data

base (e.g., examination of the individual force components comprising

the pitching and rolling moments) and supporting analytical efforts

would supply useful information for defining additional test and

analysis efforts. Potential results of such an effort could be a

method for correcting static data for single degree and possibly

multiple degree of freedom deck motions.

"o A parametric test program utilizing 2, 3, and 4 nozzle arrangements

with corresponding inner region plate models is recommended to iso-

late the deck motion and configuration effects on the fountain

forces.

"o Parametric data at additional amplitudes, frequencies, and neutral

point settings are required to develop data correlations with

greater statistical confidence.

"o Testing is recommended on a single representative V/STOL configuration

with exact random ship motions generated from Reference 2. This

testing should be conducted for more combined motions and should

include predicted aircraft motions superimposed on the deck motion.

"o Investigations should be performed to more clearly define the effects

of planform to nozzle area ratio.

"o Scale effects should be investigated by comparing small scale data

with large scale data on a configuration such as the Harrier.

"o An investigation of the effects of ship superstructure and the

associated turbulence due to crosswind is recommended.

"o Effort should be directed toward assessing the effects of aircrafL

position relative to the deck, which resimts in different jet

impingement i(;catiuns.

172

o A computer simulation is recommended which would include six

degree-of-freedom equations of motion, a ship motion model,

dynamic ground effects, a ship superstructure turbulence model,

and mathematical pilot model or autoland guidance equations.

173

7. REFERENCES

1. Meyers, J. J., editor, "Handbook of Ocean and Underwater Engineering,"

McGraw-Hill Book Co., 1967.

2. Baitis, A. E., Meyers, W. G., and Applebec, T. R., "A Non-Aviation Ship

Motion Data Base for the DD-963, CG-26, FF-l052, FFG-7, and the FF-1040

Ship Classes," DTNSRDC Report No. SPD-738-01, December 1976.

3. Schuster, E. P. and Flood, J. D., "Tmportant Simulation Parameters for

the Experimental Testing of Propulsion Induced Lift Effects," AIAA Paper

No. 78-1078, July 25-27, 1978.

4. Kotansky, D. R., et al., "Multi-Jet Induced Forces and Moments on VTOLk Aircraft Hovering In and Out of Ground Effect," Report No. NADC-77-

229-30, 19 June 1977.I

,I

f

17

I 7,3

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A

;Il•" • • i . ... ... • ' .. ........... " • ....• ••'•''•j'•''"- '•''•'-•••'• J•'"' I

-- o~ .. • 1

f I

i , I

i , 70

a

INFRMAION*5 *~

IT- I I I* -~~M: -7 7-'~.~

29 September 1978

NADC-77-107-30 - VW(I

ERRATA-March 1979

"The folloving corrections are applicable to NADC-77-107-30,

"Lift Systgn Induced Aerodynamics of V/STOL Aircraft in a Hoving

-0 Deck Environment", 29 September 1%78_:

S•page 63

Reverse the symbols in the legend.

page 107

Change the ordinate values for the rolling moment from 0.02,

0.04, etc. to 0.002, 0.004, etc.

page 114

Change e - 0* to - 0* in the description of the test conditions.

page 139

Change the ordinate values for the pitching moment from 0.2. 0.4,

etc. to 0.02. 0.04, etc.

page 146

Reduce the amplitude shown for the sinusoidal height variation

(H/D i) from ±l.5 to ±1.0 equivalent nozzle diameters.

page 149

Reverse the sinusoidal roll angle variation from leading the

pitch angle to lagging the pitch angle. The roll angle variation

-2-

ihould begin at " = -06 tnutead of +10".

page 162

Add the following Fourier coefficients to the figure.

Coefficients

A -0.026967

E- A2 0.036964

B2 0.011011

A4 0.003634

B4 0.000268

A6 -0.001497

i B6 -0.002599

page 167

Add following label for solid line: Fourier Series Curve Fit.

'I