C.P. No. 6 (8741)

A.R.C. Technical Raport < ‘.L ,.z‘tecLwiw@~ ,

MINISTRY OF SUPPLY

AERONAUTICAL RESEARCH COUNCIL

CURRENT PAPERS

Tank Tests on the Effect of Slipstream on the

Water Performance of@a Large Four Engined Flying Boat-

(Shetland I>

S. Raymond, B.Sc. (Tech.)

Crown Copyright Reserved

LONDON: HIS MAJESTY’S STATIONERY OFFICE

1950

Price 2s. 6d. net.

c.;'. ~0.6 Pi41 1

Aprd, 1945

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1 Introduction __-----

TeL;TS vere reqwred to exmsne the full scale correlatmn of tank tesTis on porpo~sm~ stability, trir snd spray on a large, four engmed flyi&& boat as effected by (1) slxpstrem, (2) degree of initial dlsturb%ncc,(J) methcd of tomng '&e model. These tests fcm Fart Of k research prog?mme' scale results2.

to mnvestlgate the difference b&men model and full

Earlxr tests have been rade to deternine the effect of slx~strem on the stab.blllty, trzm and spray of a 'aim engmed flymg beat (Lermck3), and m paribxlar to develop the teclmiqz of representmg slipstrwm on dynamlC mdcl s ~ The ccm?lete rcpresentatmn of sllpstrem was fcund to have the mqxctcd marked effect on trim, but little on spray or por- polsmg st&illty. Some 111orw.s~ m stablllty ms found for tho unstable Ltlmxk hull fsm but m goneral it -vi&s clear that the 3ffect of' slq- strem -cm small when thi null form vas c~ther very stable or very unstable. it m.8 not posslblc to make a comparison mth full scale.

The usefulness of modei sale results must depend on (1) correct representat3or oi full scz& condlmons, and (2) a knowledge of scale effect. The correct representation of the former IS now thought to rcqurro the r'ol‘Lomng ~iems tc be correct:-

1 load 0i-r vratir 2 applvx3 pitching mmmts 3 nero~xim~c tall and nmg dmpmg 4 &apt cr" hit curvi and stalling msldcnce

The majcr scale Lfiect IS :)rcbably on mterfcrcncz betwon the afterbody of a hEl1 and zhe vake frm the forebody394. This mterference appears to be a primary cause of mstc:oility, h~g31 drag and &age of tnni It high speeds. It normally brgms at a critical angle betmen the afterbody keel m.d the irnke, and it 1s thm mgie which is prOblbly subject to aercdymmc .md scale dxfferences. The degree and fom of disturbance m pltck used to examne poqorsmg stability is therefore as Important as the correct mprcsentation of other full sale condltlons.

Thx rc?crt doscnbe:: further tests made xith slqstmm "ad disturbmce In the tci-mg C,?nk at the R.A.?d:., and correlates thi‘ results mth the :~vm.lablti full ;cz& ovidence5.

2 Range of Investlgatlon

Tests on the water porpoumg sixblllty, trm and spray cFamc- tervtxs m take off md landmg were made at VW all up weights, 120,000 lb, and 130,000 lb, cn a powered dynamo model of the Shetlmd. A G.A. of tk;e Shetland T 1s giver, in Flg,l, and the hkll lmts m Flv.2. The tests on the l-&e oi'f condltlon wre made fxrst zlth slipstream on, and seccndly mthout rlipstrtam but using sclievmg loads of the correct nxtgnicude as measured in i&e tank. Thz tests m the landmg conditions 'EE mzde at 130,000 lb A.ii.1". Zero flap ws used. m all cond~tmns.

7he results i-iere exrmmed -mth respect to

1, effect of slipstrem on stabrlrty, trm and spray chxwacter- mtics of the model at both velghts,

2. effect of disturbance on the stability of the model nt both w-reqhts.

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-lO-

I - - - -

I'abie I

-II-

Fq.1 2

11 12 13 14 15 lb 17

19

1 Y-20

21-22

23-24

& hthor

1 LG. Smith

3 D.C. iNacPhai1 7" . 0 . Tye n.I.~.2.LlevelyrT

Danes

4 J.P. G&t

5 I. IhcCag

7 A.B. ilnmes R, ,J. Nonnghan

Ltle, etc.

1nterun statement 011 3 Seaplane Research Prngi-amme. Tedi. :Tote Ae?rc.l&E~D, 7907. July, 1944.

A review of the ?oqo~s~ng Instablllty of Seaplanes. Bhes/l73, 7741. rlebruay, 194k

iicdel InvesGigatlon of' the Effect cf Sllpstrenm on the Longlixdxal St&blllty of Flying Beat:, on the -.:atcr. &port ITo.Acro.1792, 6609. January, 1943.

Interference between Au No;< and 'iatcr ?low m Seapla~a Tank Testmg. Tech. I!ct? 30. Aero.~~bG, 7,006. July, 1944.

vziter sta111ty TE&S cn a saro,37 fetea with Shctlzuxl ;%lu Bottom, wing np Floats and Tall. H/R&S/l 80, a.@. October, 1944.

J3stmatian of increase 111 Ll?t dae to Slipstream. R & Ji. 17bO. Februxy, 1937.

Charts for the Detenninatlon 9 the Statx and Take-off Thrust of ? Prope?ler. Tecfi. I“ote No. A,ero.lZRl, 7x33. September, 1943.

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Calculation of the han,p2 I3 water trvn of a -- -_l--ll model due to &&ream _ _ _-__--

tank.

_---.- _-_ ---- i _ .--.- -~_.-_ l_--

-0.49 3.17 x IO5 -0.13 I+.75 x 105 -C.36 6.6 x 105 -0.01 8,75 x 105

----.A O ---

Speed, knots full scale 45

Ui due ta slipstrem -1 55,000

Estimated na au-2 to s11pstream -1.4O and thrust moment

Eeasured bo &de to s11pstream -1.4O and thrust moment

55

-62,000 I - -2.0°

-2.0°

65

.40,000

-1.7O

-1.9O

-r

L

---I 75 9,000

-0.5"

-1.1"

----A

In VIS;J of t% npproximjtions made in estmtlng the change m moment, w;noly, tk-t cm does not chnge over the change in attitude, xnd that au?-:mtcr mterference does not Ater the hydrodynamic pItchIn& moment, the cstur,atcd trim change can only be sxpected to be of the right or&r. Tne agxoxcnt obtalr.eJ. for this mcdcl 1s quite god.

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SC.& l/l 9 Shetlmd

GG’tiIlgell 436 (mod) 7.3 sq.ft 8.08 rt O-99 fY 8.61 none

4” 30’ cn ving aatu2 IO" 24'

R.A.P.30 1. I4 sq.f?t 2.52 ft 0.39 rq.rt

nclne

1.37’

0 56’ 3:5

3.3

136”

9,; cl” hem 70 35’

z” 38’

3.14 ins

17.50 lb ‘iH.94 lb

0.96 1.04

340 sq.!Y 50 ft

Aerodynm1c chord 6' 11' to Shetland hull datum

R.A.P.30 53.85 sq.Yc 16.54 Ict IS.25 sq.ft ho on taQAane

datum

4.52’ 3.5

3.3

136@

5$ of beam 70 35'

I0 32'

normal 1'5.11"

5,700 lb 6,250 lb

0.96 1.05

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Item

Engmes

Type

T. 0. ratsng

TYPO

j/z. 7: scale Shetland

PobJoy x1agam 111

85 m/3135 PBli S.L./zcro boost

Vlooden 2-blade fkxed p-Ltch

6.5 ft 3.07 0.468

FIG.3. ODEL

FIG.4. DETAIL OF AIR TURBINE AND PROPELLER INSTALLATION

FIG.5 VIEW5 SHOWING MODEL MOUNTED ,N ‘R’]:dT OF CAR,RiAGE

SHETLAND

FIG 6.

-& SARO W\No TUNNEL TESTS ON A SHETLANO MO0EL WlTH SLlPSTR~%=O~ -e- TANK TESTS ON A SHEUAND MODEL WITH SLIPSTREAM - Tc- 0.70 -.- R.A.E WIND TUNNEL TESTS ON A SHETLAND MODEL-NO SLIFSTREAM. 4- TANK TESTS ON A SHETLANO MOOEL -NO SLIPSTREAM. .-SARO WIN0 TUNNEL TESTS ON A SARO 37 M WEL- N0 SLIPSTREAM

-& SARO W\No TUNNEL TESTS ON A SHETLANO MO0EL WlTH SLlPSTf?~%=O~ -e- TANK TESTS ON A SHEUAND MODEL WITH SLIPSTREAM - Tc- 0.70 -.- R.A.E WIND TUNNEL TESTS ON A SHETLAND MODEL-NO SLIFSTREAM. 4- TANK TESTS ON A SHETLANO MOOEL -NO SLIPSTREAM. .-SARO WIN0 TUNNEL TESTS ON A SARO 37 M WEL- N0 SLIPSTREAM

0 4 a \2 16 20

WING INCIDENCE, DEG.3

SHETLAND - WING LIFT CURVES.

FLAPS AT 0”

SHETLAND.

FIG. 7.

WING 10.6”

IO 6’

INCIDENCE

.

0 IO 20 30 40

VELOCITY, F.P.S.

A /+---/ 14.6’

-0

2

0

10-b’

6-b’

0 IO 20 30 40

VELOCITY, F. p. 5.

SHETLAND MEASURED & GA~LCULATED

LIFT INCREMENTS DUE TO SLIPSTREAM.

SHETLAND.

FIG 8.

I.0

0

-x- g 35 SCALE SHETLAND

A- I45 SCALE SHETLAND

4- FULL SCALE SHETLAND

I I I - -

1 1

0 20 40 60 80 100 I20

V, KNOTS FULL SCALE

CHANGE OF THRUST COEFFICIENT WlTH SPEED ON SHETLAND AND SARO 37.

SHETLAND.

\’ + a NO FLA

\

SLIPSTREAM ON

NO FLAP 0 I

0 20 40 60 80 too TAKE OFF KNOTS, FULL SCALE 120, OOOLB AUW

+ 5TABLE

J? UNSTABLE ON 7” D15T 8 UNSTABLE WITHOUT 015T

I 1 0 20 40 60 00 100 TAKE OFF KNOTS, FULL SCALE 120,OOOLB Auw.

FIG. 9

PORPOISING STABILITY OF SHETLkND WITH AND WITHOUT SLIPSTREAM

I2

IO

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6

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2

0

-. . “\

FIG. IO m-6

d

L

f I

:LYINq qEC+ON ‘JO FLAP /

.

0 20 40 60 80 100 TAKE OFF KNOTS, FULL SCALE 130,000LB.AlJW

+ STABLE $ UNSTABLE ON 7’ DIST.

$ UNSTABLE WITHOUT DIST. I2

6

0 20

TAKE OFF

--I SLIPSTREAM OFF NO FLAP

I

40 60 80 100

KNOTS, FULL SCALE 130,000LB.AUW

~PORPOISING STABILITY OF SHETLAND WITH AND WITHOUT SLIPSTREAM

IC

6

4

2

0

FIG II. FIG II.

Wm-iouT SLIPSTREAM

IP SUSPENSION IP SUSPENSION

I h SCALE

I SHETLAND

SLIPSTREAM TIP susp.

0 20 40 60 80 100 <

TAKE OFF KNOTS, FULL SCALE l20,OOOLB.AlJW

12

IC I

6

4

2

0

SCALE SHETLANC

SSCALE SHETLANI:

&WING TIP SUSP

2% SCALE SHETLAND

I ,

dlTHOLlT SLIPSTREAM

NIN$ TIP 5USPENSlON

i

WITHOUT SLIPSTREAM .

) CENTRE SUSPENSION

0 20 40 60 80 IO0 TAKE OFF KNOTS, FULL SCALE 130,OOOLB AUW

SHETLAND-FREE TO TRIM ATTITUDES,

MODEL AND FULL SCALE.

F 1G.I 2.

1 SPEED

41 KNOTS r FULL SCALE

cv- 3.5

I I I I I I I

I I I I SPEE,D

-51 KNOTS FULL SCALE

cv = 4.4

6

4 -20 -IS -IO

v” -5 O 5 ‘O

IO

“, +\ \ a SPEED

‘1. cc” 83 KNOis \ . .+ FULL 3CALE

cv= 7.0

120,000 LB. A.UW I,d, 000 LB A.U W.

@- MAEE. RESULTS - C.C.NORMAL (30%MAC)

+- M A E E RESULT5 - ‘2.q. AFT (35% MA C)

)/I9 SCALE SHETLANO WITH SLIPSTREAM,WING TIP SUSPENSION -------- I/l9 SCALE SHETLAND NO SLIPSTREAM, WING TIP SUSPEN3lON -.-. -.- l/l9 SCALE SHETLAND< NO SLIPSTREAM I CENTRE SUSPENSldN

SHETLAND -TRIM CURVES .

.

IO -

4-

I EFFECT OF DISTURBANCE

3 EFFECT OF SLIPSTREAM -

ON STABILITY LIMITS e- h9 SCALE SHETLAND

I WIN4 TIP SUSPENSION

SLIPSTREAM ON ANO OFF OL I I

0 20 40 60 80 100 KNOT?,% FULL SCALE .

8 : KEEL

6-

4 I --

I ,. I I, I I

4. COMPARISON OF LIMITS

‘/e7s SCALE TAKE OFF CASE

0 0 i?O 40 66 a0 100

KNOTS, FULL SCALE

. . I ,. ,* --

6

: b t z 4 I I I -.

cno n a 1 EFFECT OF DISTURBANCE ?m p _ * ON STABILITY LIMITS I

m? h9 SCALE SHETLAND WING TIP SUSPENSION

(P Gig= WITH SLIP3TREAM

n o=l 0, I

0 -0 -(

20 40 60 80 too

A 0 KNOTS, FULL SCALE

IO-

SLIPSTREAM OFF

8 KEEL 3eD13T /

\ t \ ..- ^.--

6

t

EC KE

\I A I, e t-‘- SUSPENSION ,‘l ,’ v --. \ I

11275 SCALE

FIG IS. ING TIPSU6PENSt

8

6

4

2

a

ATTITUDES FREE TO TRIM (ELEVATORS NEUTRAL)

0 eo 40 60 Bo loo LANDING ’ KNOTS, FULL SCALE 130,000 LB. AVW

I2

10

6

4

2

0 0 20 40 60 80 100

ESTIMATE F

8% SCALE LANDING CASE WITH NO FLAP

STABILLTY LlM115

c

,

LAND1 NG KNOTS, FULL SCALE NO FLAP

SO,000 LE. AV W

SHETLAND

0 c

l

Ca 0

0

0

I- -

O-

O 8-

CA 0 6-

0,

0

,4 -

z-

0, 0

8-

-6 _

4-

-2-

0, 0

- \ !!!s cv

120,000 LB AU W

NO FLAPS

FlG.16.

130,000 LB A U. W I NO

OF KEEL

8 IO

KEEL

CURVES OF C, AGAINST Cv DURIN‘IG TAKE-OFF.

SHETLAND.

GA =0,9! CA

1.75

CV--

FIG.I7. EF’ECT OF SLIPS? 120,000 I b

a

-R

8.5 C*= 0’72 A = r07”

.EAM ON CHINE BLISTER A.U.W.

SHETLAND

c, : 0 79 Cvr 35 CA = O,BI d nit.,* d E 10 30

FIGIt EFFECT OF SLIPSTREAM ON CHINE BLlSi-ER 1!0,000 lb. A.U.W.

SHETLAND

FIG. 19. EFFECT OF SLIPSTREAM ON MAIN BLISTER 120,000 lb. A.U.W.

SHETLAND

CA= 0.56 oi = 6.8'

cA = z7 d 0 c,= 7-o CA E o-31

.d = 5.1"

FlG.20. EFFECT OF SLIPSTREAM ON MAIN BLISTER 12G.GOO lb. A.U.W.

SHETLAND

GA E 0.79 CA - ll.7@

C&i O.&G: d = i 1.3”

F!G.2 I. EFFECT OF SLIPSTREAM ON MAIN BLISTER

130,000 lb. A.U.W.

SHETLAND

FlG.22. EFFECT OF SLIPSTREAM ON MAIN BLISTER

130.000 lb. A.U.W.

SHETLAND

FIC.23. COMPARISON OF SPRAY ON TANK MODEL AND FLYING MODEL. SLIPSTREAM ON

130.030 lb, A.U.W.

SHETLAND

FlG.24. COMPARISON OF SPRAY ON TANK MODEL AND FLYING M DEL. SLIPSTREAM ON

130,000~~lb;~~~A.U.W.

SHETLAND

C.P. No.:6 - (8761)

A.&C. Technical Report

ptJmmtm BY Em MAJmY’S erArnrnY omce Tolmpumhamifrom:

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S!O. Code No. 13 - 9006 - 6