limited hydrodynamic investigation of a 1 15-size model of a modified nose-inlet multijet...

7/27/2019 Limited Hydrodynamic Investigation of a 1 15-Size Model of a Modified Nose-Inlet Multijet Water-based Aircraft

1/19

COPY 6RM L55T19

RESEARCH MEMORANDUM

By Robert E. McKann and Claude WCoffee

To""""""""""""""""""""""~


2/19

G*

Y

NACA L55J19

By Robert E. bIcKan~and Clzn&e W. Coffee

An i cves t i ga t i on w a s conducted t o determiEe t h e e ff e ct on th e low-spee6 r e s i s t am e and s p r ay cha r ac t e r i s t i c s md s t a t i c t r a n s v e r s e s t e b i l i t y013 e. zociification which extended the bow of E. *-s ize node1 of a nose-in let ransonicseaplareconf igurEt ion . The inve s t igat ion vas =de w i t hmd w i t h a i t t i p f loa t s .

12

An increase in bow l eng th of 0.6 bean dec resse d the hump res is ta nc eq p ? o x i r c t e l y 50 y r c e n t and inproved th e low-speed spra y ch are cte r is t i cs .Removal of the wing-ti p f loets redu ced the resis tanc e prior to hung speedbu-b had l i t t l e e f f e c t on th e hump re si st an ce . A r o l l aa gle of 8 witht h e t i p f l o c t s o f f r e s u l t e d i n a s t z t i c r i g h t i n g m0nen-l equal t o t h a tprovided by f dl submergence of th e t i p f l o a t , w3ich occurred a t a r o l langle of GO.2

INTRODUCTION

The resul ts of sz1 inves t igatLon of th e aerodynamic and hydrodynamiccha r ac t e r i s t i c s of models of two transonic, nu l t l j e t , water-based a i r -craTt were rep or te d n refe ren ce 1. The trensonic mea r u l e ( r e f . 2 )w a s used as 8 guide i n shaping these bod ies. In a n attempt t o achieveminimun t r ansonic &reg r i s e m d low wave drag at susersonic sgeeds, thesek i l s were give n high f ineness rat ios m-d s m 1 1 hall cross-sect ionaln e e . I n t h e i n t e r e s t s of ero&pzanic cleanmess, we vio ushydro6ynmicd e s i g n c r i t e r i a were de l i be r a t e l y v i o l a t ed . For thenose-i l l letconf igu-ra ti on th e bow height vas kept low, eng ine i l l lets were p lac ed clo se tothe wate r, fore'oody ve r-l ic el ch in e str ip s were Taded cu t sh or t of thebow, m d h e hull siZLes were bulge d above t he ch in es by engineductlr-g.


3/19

i

Wirg-tip f l o a ts were reta ined for both conl igure tions, altlnough they wereham t o ad& ap9reciable drag a t t ransonic speess.As m u l d beexpected, soIce un de sira ble hydrodymmic ch a ra c te ri st ic swere encoun%ered. As shorn in r e f e r ence I, %he hump re si s ta rx e of th enose- inlet coaf igza+uion w a s high, the cleman ce of the cos8 inlet a tlow s2eeZ was m x g i r a l , and the low-speed spray ar-d flow on the forebodywere heavy.The prese xt gaper deds wi th a m dif ice t io n of the nose- in le t con-f ig ur zt i on to imcrove %he lov-speed, f re e- to - t r i l r re s is ta me as w el l asthe low-speed sprayche r ac t e r i s t i c s .I nc l uded n h i s nves t i ge t i on

was "Ye efzect o r wing- t i ? f loa t s on th e low-speed re sis ta nc e. Thes ta t i c t r a mv er se s% bi l i t y ( r i gh t in g mo3en-l a t r e s t ) of t i e h u i l andw i g 4 with and v i t h o u t 5 i p f l o a t s w a s d s o determined.

Ee e le n to r& f l e c t i o n e f e r r e d o ta b i l iz er chord, po s i t iv e when% r a i l i n g e Q e i s bo=, deg6f fSap ef lec


4/19

3The long i tu6 in a l d i s t r ib u t ion of c r os s - s ec t i oml mea was m i n -tailzed snoot'r. and fair f o r t h e a l t e r e d b o w as s h m i n f i g u r e k . Thernodification was faired out a t appro-tely 65 f e e t (full s ize) behindth e or ig in al bow.

d

A descr i2 t ion of Imgley tenlr no. I and th e towtng c err i sge i sgiven in reference 3. The node1 was f i e e t o trim and ?re e t o r i s e b u twas oth erw ise res tra ine d f o r t h e s e t e s t s . Tri md i s e were taker aszero Then %he forebody keel E t t h e s t e p w a s t m g e n t t o t h e u n a f s t u r b e dwater surfece.

The f r ee - to- t r im res i s tm ce of th e co ql e- le model, inciudir-g .zirdreg of the model u ld towing staff , was determined f o r v a i a z s stabi-l i z e r m d elevator def lect ions over 6, ange of constent speeds with0 flep def lec- l im. Tie a i r drag of the towing staff vas subt rac tedgreghs were obtained during these runs.- as a tm e f rcn t h eo t e l e s i s t m c e . S p r q o bs erv at io ns ant5 photo-- T r h ' a n dt a t i co l l f n g moment were recordedithhe -Lip f l o a t son end off. The m d e l w e s mom tea free-to-tr im 011 a 3 y n m n e t e r f ixedt o t he towing staff vhich rr?easmed ti e r o l l i n g moment f o r a range ofs e t t i n g of the roll aagle . r

XESiJIZS AND DISCUSSION

Al values as presented axe full s i z e .The t o t a l r e s i s t an ce md the corresponding t r b m-d rise or" t h eextended-bow con3gurztion md t h e bas i c coo f i gme t i on for var iouse leva tor an d stzibilizer CieTlectioos are shown i n f i g u r e 3 with Oo f la-gsand EL gross load or" 160,000 pounds up -Lo e sseed of qprox5mately100 kt lots. Tne re s i s t r r ce ' of the extended-bow configuretion wasE.pproximately 50 pe r ce r t l e ss t h a t h a t of the bas ic conf igurat ion,increas ing the huqs gross- ioed- to ta l - res is tmce r a t i o f r om 2.3 t o 4.5.The s2eed a t which i-?unrp r es i s t ance occwred increased f r o m 48 -Lo 55 h o t swhen t'ce bow w.zs exLended. A t speeds above 100 h o t s themodifiedpor-t i o n 02 the hull wes not wetted .znd no significctrit IlifZerence i n resultsvould be expected.

I Increases i n both trlb and r i s e o c cu rr edr io r t o h u q speed as zresult of th e bok- exbension a d were accoEparlled by e l h h a t i o n of flowabcve the chin e md cver the bulge o f th e fcrward engines th&t had been-


5/19

4

presez t 01"- t'ne basiccon figw atizn . T'ne decreaseti esis- lame re s u t e afrorr. t h e higher trh" U-gLe, the les ser we tte d =ea, an& th e el M na % io nor' the flov alo ng the tran sve rse cu-rvetilre cf the forward engines.kp r cveaen t was elso raarlred in the gre ete r cie arm -ce of the engine ill-l e t s f rm t3e bow spray.

The %tal resistzisee, t r i m , and r i s e f c r E. gross load of200,000 pounds (25-2ercen-L zverload) a2-d 0 fla-gs are presexked i nTiowe 6. The speed f o r ~LT-? r e s i s t enceremice2 about 55 kro t s . Thegross-Icad-hump-resistance ratLo i s ebout 3 . 3 as coxparedwith 4.5 a ta gross Loa2 of 160,303 pour,ds. Spray a t th is over losa kondi t ioo wass t i l l e cc ep te ble , a lt ho ug b l i t t l e r e s e r v e c l e w a c e of t h e e w i n e ir -is% i s ava i lzb le for oper a t ion in waves.The efiec-l of r em v i ng t i p f l o a t s on re s is + ,u l ce , t r i m , err& r i s ei s shs-m ir!E g n e 7. P r i o r tc h u q s peed ( eps r cx i mt e l y 55 knots) as l i gh t f nc r eas e i n t r i m r e s u l t ed Zrom t'ne removal o f th e t i p f lo a t s ande. decrease in r es i s t an ce wzs rot ed . The de cre ase nresistance wasa p p r s x 3 a t e l g 2C percer-t at 40 kmts end 11percent &t 35 h o t s . Therek-as l i t t l e charge ir, t h e h k p re s is ta nc e. Without thedisplaceaent oft h e t i p f l o a t s , The kc11 r ises s l ightLy deeper in the vater a t l o xspeeOa b u t r i s e s sorcewhaz f a s t e r as +,'lie model trim higher a t hunpspeed wi-lhout tke restr &i ri_ r-g nega tive nonent of the Tloets .Sprzy phozogrqhs of the Sa s ic and th e extencled-bow corS'igura-bionss r e sho-tm- i n f i g u r e s 8 and g(a) , respect ively. A t 22.9 knots hegreater c learance of the en gin e inl ets of th e extended bow ahead of andebove the bow sgray i s v i s i b l e . Also evidez t i s theeffect iveness of


6/19

cby the wing rightizg monent -atila r o l l angle of 4" is reached a t th enorrzl-loadcor? ditic n. The ri g h ti n g moment of th e t i 9 floaz f u l l y sub-

4 i omerged a t a r o l l a ng le of 45 i s equaled by she moruezt due -io t he wingbuoy~ncy wtth the ?loat ofl" e t ar? angle of roll of 8 i n th e normal-load condizion. A heaviergross-load conditions th erighting momgnt, i ' L -H - L ~ c r without tis f l oa t s i nc r eas e s with l o a d f o r a given angle .of r o l l .The t r i ~ s r e t h e s m e o r s l i g h t l y g r e e t e r w i t h t h e t i p f l o e t s o ff as t h emodel i s r o l l ed .

4 modification extellding the b sw and ve r t i c a l chFne s t r ip s of th eno se- inl et tra nso nic seEtplane con figura tion was found t o r e s u l t i n s.50-Fercent re duc tion i n tile hanp resis-a nce , Tncreesed en gin e-in letcleerznce, reduced ov-speed spray and hul l - s ide flow, and accesteblespray and r e s i s t znce a t 25-percentoverloaB. Removalof thewing-tip-. f l o a t s 'h~es ound t o r educekeesistence prior t o h-mp speed, bat t ohave l i t t l e e f f e c t 011 the 3 u ! es i s tance . The s t e t i c r i gh t i ng momentprovided by f u l l submergence of t h e t i p f l o a t s &t a roll angle of 4-10

I 2v a s equsled by t i e xoment due t o the vir?g Suoya~cy &th floats off a ta roll angle of 8O i n t h e norml-load condit ion.

Largley Aeroneil t ical kboratory,Bationzl Advisory Committee for Aeronautics,U n g l e y Fie ld , V a . , 0c';o'oe-r 21, 1955.


7/19

6

1. Olson, Roland E., and Bielat, Ralgh P.: AE Aerodynamic and Wdro-dynanic Investigation of Two ?lultijet Va';er-Based Aircraft avingLov Transonic Drag Rise. WCA RM L55Alla,1955.2. W-itcoxb, Richard .: A S tudy of the Zero-Lift Drag-Rise Charac-teristics of Wing-Body Combinations N e a r the Speed of Sound. NACARX ~ 5 2 ~ 0 81952.3. Truscctt, Starr: The Ehlarged N. A. C. A. Tank and So-m of Its Work.XACA TM 918, 1939.


8/19

(b) Extended-bow conf igurat ion. L-905304 Figure 1.- Pnotographs of the nose-inlet model (Langley tank model 323).


9/19

\ \- - E-_-'4 "_ "

II 89'.'- 69' -. "-Ee"" ""- --.- " E.35" - - --"Figure 2.- General arrangement of nose i n l e t configuration.

I


10/19

L

I- 8.9'

--------Basicow- -Extended bow

II 17 20 23 26 A.P.58.4' "_ """_ -

165.5' c


11/19

_ _ _" _ _ ""

Net area"0 Basic-bow---u-Jbtenlded-bowArea of equivalent arabolicbody of revoluiion

-40 ' I I I 1 I I I I I I I I I I . I 1 1-10 0 10 20 3 40 5 0 6 0 70 m a T $ loo 110 120 13 1x) 1 9 1601 Distance from forw perpendicular, ft-2 0 2 4 6 8 10 12 lb 16 18 20 22 26 28 PHull s ta t ion numberFigure 4. - Area dtstribuLion of nose-inletconfiguration. (Alldimensions m e fuZ.1 s i ze . )


12/19

.\.

6bo2

2

0

0

-2

-6

-8

Figure 5.- VmizLion of total r e s i s t ance , trh, a- d r i s e w i th speed .Tipf loz t s on; 43 = 160,000 Ib; 6f = Oo .


13/19

100

0

2

0

0

-60 10 20 9 w 5 0 0 0 7 0 ~ 9 0Speed, knots loo 110


14/19

100

r lP

0

8

6

2

0

-6

Fi g w e 7.- E f f e c t of t i p floats 011 the t o t a l resistance, trim, end r i s eof t'ne extended-bow collfi,wation. & = 160,000 It: 6~ = Oo .


15/19

74 L NACA Ki L55Jl-922 .9 knotsr / = 1.80

40.1 knots+ = 2.00

57.2 knots4 = 5.40

L-87535F i g r e 8.- Spra y pnotogre@s of basic-bow configura t ion . L+, = 160,000 U;Sf OC .


16/19

Speed, 22.9 k n o t s ; trim, 2.1'

Speed, W . l knots; trim, 2.8'.

Speed, 57.3 knots; trim, 5.5'.


17/19

16

Speed, 22.5 k n o t s ; trim, 2.3'

Speed, 40.1 knots; trim, 2.9O

3igure 9 . - Concl-AeS.


18/19

NACA FM L55Jl9f

d

lb

4

elaM 2.5& O 0 4 g 12 16 0 4 8 12 16

Angle of r o l l , 8 , deg(a) T i p T l o a t s off. (b) T i pl o a t s or?.

Figure 10.- S t a t i c p r o p e r t i e s of extended-bow configuration.

NACA - LangIey Field, Va.


19/19

I

I

limited hydrodynamic investigation of a 1 15-size model of a modified nose-inlet multijet...

Documents