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NACA list dtd 28 Sep 1945; NASA TR Serverwebsite

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JTECHNICAL NOTES ‘

NATIONAL A3VISO?LY COMMITTEE 10R AERONAUTICS

.,-. —

i;

“i

No. 836

HYDRODYNAMIC TESTS OF A l/10-SIZE MODEL 03?TEE

OF THE LATiGOiEE 521 FLYXNG BOAT - HACA MODEL

—.-——=- ---— ..:

HULL

03 .—.

By Roland E. Olson and Lindsay J. LinaLangley Memorial Aeronautical Laboratory

“ cf.AsmEL.~.T%&d ~t eoatakc?asa&dinfm&n~gthe National D&Iae of the L$hed Stateswithinthe~ing of the bpignage ACL Uw 5&31~d 32.fta*anAa&Q a themvehion of iti contentsin~me.nner toautmadorizad perwn iap,ohibtibylaw. Mxmatiou ao claaai6edmny be impartedonlyto ~aons’in Ae miiita~ ●nd naval fkxvi~ of theunited~appmptie”civilian cfficeraandemp]ve~ : . :oftheFederaIGwemm~t whohavealegitimtieint~~t .’ , ~k+, andtoUA4%~d&entofhmlWa~ snd -

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dimcretiouwho of nece&ty mustbe informedtkeof. ,, ,,}.,-;,=-,.- ; +--+- -- -,--- .t

[.,::., 1.,:,,

WashingtonDecember 1941 ‘

....-----— .—.-—

-. -.—-

,— .—-— ..

-. ,

NATIONAL ADVISORY$COMMITTEE-FOR A.ERCNAUT!CS.. .. .-. -..

. . . TECHN~CUILNOTE NO..8.36 _ . ._ ..__._-–.,_... .....-.: ...’. ... . .-

,-jIYdItODYNJiJHCTESTS OF ‘Al/10_SIZi MODq+ Oi’itiE-@LL ‘_ _. -.

.... . ..O* THE LA~~CO~RE 621 FLYING_B9A~:.;.~ACA.lfODEL,...-. —-

--- ,83 _ ‘_.: ,.-—.By Roland E. Olson and Lindsay J. Lina.. ~, --

. .“ -.\. .

SUMM& :““. ,... .. . -.. .

“Al/10-size model of the hull of the French

—.

. . —..- -.___.e.=_—---.J. -.

.

- —— .——--—-- ..-.

flying. .bo?.t~atgco>re 52L”was .teitedin.t”hk~ACA tanks ~hism’?~.&l~.is”.oneof a“-’series“ofmod-elsof ,the hulls of ac$u~lfl.yin~bq,ats’of b.,o.tjhf’.;reignand domestic type tha-t_,~g.ebeing teste~ “in”the NAGA tank .toprovide in~ormatzon ??e- - ‘--‘-_’_garding”the water .ch’aracteristicsof a variety of ferns;f hull and to illustrate tha development”of present~daytypes of flying boat. The lines end the offsets of thehull were obtained from the manufacturer through theParis Office of the NACAO The form of the stub-wingstabilizers was not furnished ~ndj therefore, the model’was tested without them. .-

,. ___ .-The model was .kest.e~free ,to.%ri_rn‘a;..t~edes”~gp.ini-

ti~l load (initi.aL’-Laadcoefficient of.0-428) and by thegeneral method at’load”coefficients from 0,025 to .0.6.The spray characteristics of”the model are good. CTbeform of the bow would be par.ti.cularl,ydesira~le for rough-water use. The inteyfsrence of the afterb.odyand thetailextension .isexcessive, causing very high re.eiste?ce.athigh speeds. A vtolent vertical.instabilityis.p?ese!?t.at trims of 4° and 6° with.light Loads, and h,ig.hspeeds~

, .,. . ., . . .“,.

“ I.N~RdDuCTI,ON~.“.- ,-.

- .. . - - .r- .—.. --. . .

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.—

.—. .-

.—

-—

, . .. L ,- . —: ...- . . -*. -- ;-

. .

. .- -——.= .= _ ,.

,.. .-;.. .-

Tests of.modelis’ofhulls of successful‘flyi~gbo,atsare i’ncludedin the.program of re.~earch.conducte,g-_a.?=,*Ec! .._.=.:NACA tank (references 1 to 8’).‘The results Of these

-..=+

,testsare intended to provide information regarding thewater “char”a”cie’rip.tics-of a,vari”etyof ~%r.rn;s.Of hull Bnd+0 illustrate the develo,p~ent.of present-day types of fly-

,..in~.b~ate . . L .-,. :..- ...- .....’ ‘. .- .--:

.. . . . . .2 NACA TechnicaX No”teN0.-836 8

The subject test$’’weremade an a model of the hull..

of the flying boat Latc$co&re.521 (f’Lt.,de Vaisseau deParisJ1),designated NACA mo.de,l83.. l?hie.flying boe.t,whi”chWAS built’in France’in 1934’and which at one timeheld the longvdistance ~ecord for-flying boats, was.con-structed’primarily’”fortrans-Atlantic operation. I

The lihbs”and offsets’’of”~hehull’”werefurnished bythe manufacturers through the Paris Office of-the NACA..Data for the stub--wingstabilizers were not included inthe data furnished to the’NACA; consequently, the tankmodel did not have stu%-wing stabilizers.

c ,,These tests of the hull without the ’stu%-wingst!?-

bilizers “are.of”qpeqialinterest>ecatise t-heform of thehull differs .fr~~that generally used on American flyi,ng.,boats. It has”a rounded %o~,tominstead of the usualsharp keelwb?, main .e~~p.is e~trernely-e~alloyind ~~unusual”form; ~rimt”t~e angle“of afterbody keel is v-er~...,small<} . , , 1 ,’ .. . .

. .. . . . . . .. .. .,, t-..

. .DEsCpIPT;T-Oti’’0F,THE MODEL ; ‘

1“ ,, .. ....,‘.

The model, l/10-fu~l size,,: was built of laminatedwood,according”to the lines shown in figure 1 and”theoffsets given in table $’. ~hotogrkph$.of the model are

,.-shown in figure 2; - ‘::., ,. .:. ,... , -,..-..*.... ..

.,,The rnoapl”h~s”h””$ei’ati+el~?loggfdr’ebod~ with the

keel ,carrledlo,w,andwell’ f;orwa’$~;~dwith sharp V sec-tions at ‘t’hejbQw..The”angle O* d+”adris~ at themainstep i.s,20°“1.5.*.and’,.tfie!bo?}”om-~e.cti”on-~_.&rearched togive a large “ohinefl”are’i‘Th’”6keels of the foreb”o”dyandthe afterbody are transversely rounded, ae in HACA model74 (reference 9), but.a-sharp,keel is formed near the bowand near the second step;““’Tlieafigleof aead rise on theafterbody increases towerd th~ stern p~st. Chine flareie also used.on the aft.eXbody..bottop_just aft,of the mainstep. The .t&\lappendage h:~s..straightV: ,s,ectionswithno curvature,‘atthe chine: -i: .,

The mi~n,st~ep.”is,sk’@l.0\’’’~O=37in:, “OnJ~O’”21>bam) andis not vertic~l, .asi,nAmerican ,designs?but “s.lope.saftfrom the forebody to the afterb’ody. The second step(0.46 in.) fades out at the ohine and also sldpes towardthe tail extension. (See fig. L.)

●

—

,.

.

--

-.---.

b

●“ ‘-

. ,

-.

NACA Technical Note No. 836 3

,

.

The angle of”afterbody”k~el”is 2°11[ with fiesPectto “the straight portion of ~he forebody’. The keel of thetail extension is straight and at E@ ang~e of 120 481 ‘ithrespect to the forebody.

The lateral stability of the full-size flying boatwas provided by stub wings attached to the hull. Lack of,informationas to the size and,the form of the stub wingsprevented their-being used on the &o’del. ,.

The particulars of the model aridof the full~sizeflying boat are as follows: . . “.

.. -.l~ -,. . .,..- , ——.. - “Model. . Ful-l-size

Length:

li6;65”i6.‘Over-all “..“. . .,.. .“. .-” . ,: -97.21 - “-----””--,

., “ 54.53 in,Forebody . . . ~,.“~.;.● ““ _..;?:, 45.44 ft

.. . ..A—

AfterbQdy”. . .’. . /. ~.”” “26.37in. 21.98 ft,. .,”- Tail”extension”. . . .“. : ; ““”35.75 in: 29.?~ ft

,,Maximum beam . . . . , , . . . . 17.72 in. 14.77 ft..‘... . .!

Center of moments:-.””“’.. .:””

Forward of main ,step., , , ..,.fi.7..48in~ 6.23 ft.-. ,.., ..... .

Above keel . . .1. . . . . . 12.80 in. 10.67 ft

Dep’tliofmain ‘@t’ep . .“o ~“, 1 .’; 0=37 in. 0.31 ft,. ,... . ,.. ... ..... . . ._., --.+_....”” .- \ ....Dept:h’ofsectindst”ep”~i“keel ,.. ., 0~A6 ‘n’ _* , +.O 38 f-t .—__

Angle of afterbod.ykeel . .. . .“ - “ 2° llt,.

Angle of tail-extension kee~ .: .‘“’:“ ““”<~-~o481,’

Gross load -.:., F . .. . . . ..”~-f87.4 lb .88,184 lb,.

Get-away speed . , ., . . , i ,,.,~7?5.~P.s..,.. 80.8 mph -.

Linear ratio of model.-%ofull size 1/10.,“ . . . .....-

,,. ~ .,,.. . .. . .

4 NAOA Technical Note No. 836.,.

..,.,, .,: ,. .’,” :, .,.:

.,‘~”~Add,i<t~o’nal“tests””ofthe tiodelwere made with the teil,,,.,1

e’xtensio”riremo-vedat ‘tH6 se’condstep. For this portion ofthe investigation, the model was designated model 83A.. . ... ,“. .,,- ,..,.. .

.,,., APiARATUSAND “PROCEDUREt,... ,,.,

.. .A,detaile;”desoript.ion.of the tank, the towing equip-

meri~’’’”anth~e~emethbd of testing are given in reference I.0,The model was tested, free tb trim,”at onejgrosa losd andone.get-away speed. Fixed-trim tests were made by thege%eral method. ‘.Inesmuchas the investigation was intendedto study the behavior of the hull rather than to providedesign data, the tests did not include all ?osgible CTn-,ditions of operation.

. ..The position of the center of gravity of’the complete

flying”bos.tas shown on th,eor.igin,ellines was used as thecenter of gravity for the free-to-trim tests end the cen-ter ‘ofmoments for the f.i=ed-t.ri.m,tests. The free-to-trimtests.,of the model with tail extension renoved (model 83A)wer’e’made -withthe mode~ balanced about the center ofgqq.vi.t,yby placing weights on the afterbody. The properloait’un the’water””wa.s.alia maintained. . ,

Photographs were taken for a qua~itative record ofthe wave form and the spray characteristics.., ..,, --..,. ,. ~.i. .,

., ..RMSULTS,AND DISCUSSION..

., . . ..,.The results of the tests were reduce~ to the-usual

ooefficien%s based on.Froudets law in.order to meke themindependent of size. In this case, the maximum beam waschosen as the aharaoteristic dimension. The.nondi.men-siona.1c:oeffi,cientsare defined as,fol~ows:..,,

.’ ,,,

Load coefficient,.’

Ca = A/wb3,, ..

Initial load coefficient, GAO = &o/wb3. . . . . . ..

Re&istence coeffio.iemt,.CR = R/wb=

.,

.

—

Speed coefficient, CV = V/~gb

—

NACA.Technical Mote No. 836 5.

.

.

‘3

,Gek-away speed coefficient, v~/- ,... Cv =,,, .. .... . ... . .G..

. . . . . . . . . .

. . ‘ ~r~mming-mo~entcoefficierit; CM y .M{wi‘ ...-. ,- .- ,—+ ,

...= RTse codfficfent’,“.C~”= r/b ‘ . “:” ‘ “~

.. . ... -.,“ .“:., .,, -,- -. : ~- -. —-A .-.

where . . ... ..-..

A“,

load on water, pounds

A. init~ial‘load on water; pounds i... . ,,,, ,..

. . . . w .spec.ificweight of water, pounds per cubic foot., . (6.3.4for these tests, usually taken as 64 far

~qes,wa.t;er).- . ..,.,

b maximum “beam”,feet. .-.. . .—

‘~ ~a~er’~r,e~i’s.tence,pounds I.,.

..-. ,.

V“’“spiei,”~feet.pii sec&ri&,,,”..,.. . . 1

‘vG” - .’~ge.t-,aw.anti.‘,s.peed,”‘feet,pe:r”second’‘“.... .

.. . . . . .g accele”r-atlon’of gravity, ‘32..2Yf&et per secondf;. . ~ p*r-$e&on& .“. ,- .,. -,-’.“. .

...:.-. ..-; . . . . ...,-------.‘“.M trirnnritigrnohenti@oun&-feet ‘.‘

,.,t“.”“ .,

.-.:, .-,-”-. .-e----- --- ,.-——— —.....-...~.-.“_.. .,. ..-..- -.. .r rise at center O* gravity”(height above posi~i~n

at rest), feet.,->..,.- ,. -t .,... -..,, ,.’”.”’’...

‘ ‘Any.~onsistsrit~%yktembf unit:smight-have been us&~.The trimmln&-abmefit”dkt&are referred t6 the center of.mutaetitsshown in $tgurk 1.” l!ail-heavy<~oments.are-con:;sidersd pa$it%ve~” Trim (T) iS the-img~e betweerii%e-~aqellne’of-the model””~ddthe hori~ont&~~ ‘“ . ... ,: .,, ., .. ., .. .>,,, .“+.. &..*--!’...--., .“

‘.’Fre~~tO fFiM’,““mOdel‘83~-““The”r6#ul~sof”t~e ‘f~eq<~o-. trim tests for the design conditfori:of~o&dia~”(CAo =“ ‘-

0~.428).~qd.ge.t-away..s?egd(,C~G,=:fl-.5~?).=.a.Ze;pJUtte&.:1.infig-. ............ ....’----..- .=

<__!f

--

—...,-

—.

-

—

.-

.“

6 NACA,Technical Note No~.836

The wave formation and the spray e.tlow speeds areshown in figure”4(a). The fine entrance resulting fromthe low keel and the sharp sections at the bow producesonly a low sprayt and,the :f’lyin’gbo’atwill probably runvery clee.nlyin rough water. This low spray may be duein some extent to the unusual~y J+owloaci;coe.fficientatwhich the test was made. The tests ‘ofthe model show noindication of any lateral instability when the flowbreaks away from the after portion of the hull at lows$eeds.

The maximum in the resistance curve (the hump)occurs at a speed coefficient of 2.4. At “thespeed rep-resented by this coefficient, the model planes on theforebody and the ~fterbod~ “andthe’tail ext”ens”ionis stillwetted”by spray from under t“he”second st”ep,”The smallangle of afterbody keel is effective in keeping the trimat the hump at the low value of only 7.3°. The load-resistance ratio A/R at the hump is sbou”t5. Thisrather high value of A/R for a free-to-trim test may beaccounted for by the fact that the.atfitude of the hullis near the trim for minimum water resistance (best trim)at this speed. Photographs’(fig. 4(b))”khow the iave pat-tern at the hump speed. The forward portion of the sprayfrom the forebody is low aridalmbst-horizontal,

Over,.thehump, the.,trim,~ndthe ~esis$agce ~ecreaseslightly and the a~terbodj And tail extension are clearfor only a limited range of speeds. The model had aslight tendency to porpQi:e as the aft?rbody came clear,but readings of resistance, t~imj‘etc. could be made with-out ,re~?ra+p>ngWe .Qodel,:}n.Ritch. . ~.,.. . .. .

~.At high speeds the trim incre;ses:‘resulting in a

large de,~ar,tur,efr.o:qt.r$a.for.mini~qm water ~esiqtance(see”fig:‘,6(b,))’send,,a’s:q,q,o,nd.hu~p o,c.c,~,rsin.the registencecurve. ‘The~o,w,’ari,,g~~,.of+,fter.body‘ge.el&d the shallow . ,step do n~otpro,vicie.cl,ear’an.ce,for~.”utheafte,rbody,and theafter p“”lanin’gsurfaces”By.%he.avi’ly+,~,ettedmear get-awayspeed (fig. 4(c)). Tlieshall’ow’kecond”step, which fadesout at the chines, ,is,in,e~fect.ivein,~reak$,ngthe flawf“rom’the’tail e~t,en”si,onc: ‘ “’. ““.“

., ~ree..to,,t~im,,,.mode~. 83A .(ta’i~ ‘~Xtension-removed),- ‘The free-to,n.jrimgq~ve,s,fo~ ~odel 63A are ,includedin fig-ure 3 with the free-to-trim Curves’for mo,del83.

.

.

NACA Technical Note No. 836 7

Below the hump speed, the resistance-and the trim’f’ormodel 83A are greater than for model 83- @his result in-dicates thatat low speeds the tail exteneion of model-83produces an effective lifting force and causes a

~ ZZositive.LbowuP) moment -rThe hump is-shifted to asp6e7(CV = 2.0) but the~magnitude of the hump resistanceis not changed. at high speeds the trim and the re&ist-ance for model 83A are reduced, showing thatt-in ‘model83,the tail extension produces a downward force causinghigher trim and resistance~ The same hump in the resist-ance curve at high speeds occurs for model 83A but to alesser degree.

Fixed-trim tests,- The fixed-trim results for the ““model with the tail extension are presented in figure ~,The resistance coefficients for a series of loads are -plotted against the speed coefficient for several trims.A few cross plots of the type generally used by the NACAare included in figure”6. Theuse of these curves is de-scribed in,reference 8.

. .,The resistance char~cteristics o-fmodel 83 are som–e~

——

what different from those of most models tested in theNACA tank. Instead of sn.appreciable decrease in resista-nce just beyond the hqmp speed, which is generally’as–-“ .-

sociated,,,witha decreese in wetted ares over the afterportion .o.fthe hull, the resistance remains practically”the same (T =,.6°or ‘T= 8°) or continues to increase .(T = 10ff). With the low angle of afterbody ke”eland theshallow step,--the,afterplening surfeces are”-in such a

.—_ —.

position that the water frnm the matn step generally willnot clear..t,heafterbody. With the heaviesf loa-ds,-how-ever, the trough formed by the fo’rebodyis deep and for avery small.range of speeds the afterbbdy“and the-%Kfl &x~-tension are.clear of the water. At low angl”esand hlg%- ‘,speeds the resistance iS high becsuse the wetted lengthforward ‘ofthe step increases and more than compens-atesfor any.reduction in afterbody interference. At a .trihof 10° tihelight”loads are supported by the after plsning’surfaces. ,.. “.

.“” .,Figures 7(.a\to 7(c) show the spraY at a ‘fixedtrlrn””.

of 8° for three loads and speeds. At low speed, Cv.’=-1.30 and C* = 0.4, the sides of the model are wetted..andthe,tai,ldec”k}is al~ost un~er water ~fig.,7(a))~ As’thespe:edin,cr’eases“overthe hump the’afte.rbody“tendstoolesr’,~,ut,a fu~ther increase,in speed causes.the water. . ,,

... . . ,’.. ,-

“8 NACA Technical Note No. 836

from the main step again to strike the after”bodychines..(fi”g.7(b)). For the light loads the main step is ve~y“in’effectivein breaking the flow from the afterbody and-as a..resultthe”afterbody just behind the step.is wetted.At high speeds (fig. 7(c)) the afterbody and the tail ex-tension are heavily wetted.

Best trim.- The.fQrce characteristics at trim fOrminimum water resistance are given in figure 8.

Vertical instability●- At high speeds and light loadsa violent vertical instability was evident at trims of 4°and 6°. The model appeared to be sucked down into thewater until the ‘flowchanged and sufficient lift was de-veloped to cause the model to jump completely clear of thewzter. This same type of instability was noted for testsreported in reference 9. These’~nd other tests indicatethat the instability appears when.the step i.snot of .suf--fici.entdepth. The instability occurs over a aange Oftrims of several degrees. The instability does not appearat 2°, where the afterbody keel is slightly above the hor-izontal.

.,.

The instability prevented complete data being takenat high speeds for the light loads. The free-to-trimtests did not show this characteristic because the trim,throughout the high-speed range, was above that at whichthe vertical 2nst~bility occurred. (See fig. 6(b).)

.’The effect of thie type of vertical instability on

porpoising characteristics should be investigated by useof a dynamically similar model; that is,”amodel with themass and moment of inertia corresponding to the full-s’izeairplane. NO information has been received on the ‘corre-sponding behavior of the full-size fl,vingboat.

Stickin+z.-At trims of 6° and 8° (model 83) the mo-ments change ,fromnegative (bow down) to positive (bow up)values at high speeds. A change ofimoment in this direc-tion does not o“ccurin most models at high speeds. Thischange of moment indicates that the model is probablysticking because of the flow over the after planing sur-faces.

The resistance and moment coefficients fourmodel 83A(tafl extension removed), at a trim of 8°, are shown infigure 9. With t~’k’tail extension removed, the momentsbecome and remain negative at high speeds. When fi”gure5(d) (model 83) is compared with figure 9 (model 83A),

●

✎ ✎

NACA Technical Note No. 836 9

the difference in moments indicates that a downward; orsuction, force is developed at highepeeds because of thepresence of the tail extension. Photographs in figure 7show an increase in wetted area forward when the tail ex-tension is present. .-.

In figure 10 the position, the magnitude, and thedirection of the.resultant force are shown at severalloads and speeds for model 83 and model 83A. The trim ofthe hull is 8°. These vectors were computed from thefixed-trim data.

,,At low speeds (Cv = 2.0) the position of the result-

ant force (’fig,10) is farther aft for model 83 (with thetail extension), indicating a lifting force over the plan-ing surface of the tail extension. (Note the roach in thelow-speed photographs, figs. ?(a) and 7(b).) As the tailextension tends to come clear of the water (Cv = 3.0) theforce vectors for the two models approach one another.As the speed increases, the water again flows over thetail planing surface (model 83, figs. 7(b) and 7(c)), andthe resultant force moves forward with decreasing slope.The vectors for model 83 at speed coefficients from 4.5 to7.0 show the resultant force intersecting the forebody;whereas the resultant force for model 83A intersects theafterbody at all loads except CA = 0.1.

.

CONCLUSIONS

Because of the absence of the stub wings, the charac-teristics of the model are not completely indicative ofthe performance of the full-size flying boat.

The spray characteristics of the hull are good, butthis result may be due in some extent to the unusually lowload coefficients at which the tests were made. On thebasis of water performance, the form of the bow appears tobe good. The chine flare iS effective in holding down thespray.

Because of the low angles of afterbody keel and tailextension, a lift is produced at low speeds that is advan-tageous in reducing the trim at the hump where the avail-able control moment is small.

., ~..Thehigh-spbed resistanc~ iS excessive because of the.laclcof clearance”.in the afterbodyand teil ex”tensioni., ,.

---- At fixed trim’sof 4° and 6° a violent”ve’rtic~lin-stability appears at light loads and high speeds. Thisinstability is probably caused mainly by the shallow step,Knowledge of the-full-scale behaiior iS desireble for in-terpretation<of this type ofinstabllity.

,... .., .,, .,.

Langley Memorial Aeronautical Labor~tory,Natic).nalAdvi$ory Committee for .}erdnabtics$

Langley Field, ‘Vs., 0ctober13,”294-1, “

.,

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1.

2.

3.

4.

5.

6.

7.

8.

9.

..

10..

NACA Technical Note

REFERENCES

No. 836 11

Shoemaker, James M.: A Complete Tank Test of a Modelof a Flying-Boat Hull - N.A.C.A. Model 16. T.N.No. 471, NACA, 1933.

Dawson, John R.: A Complete Tank Test of the Hull ofthe Sikorsky S--40Flying Boat - American ClipperClass. T.N. No. 512, NACA, 1934.

●

Bell, Joe W.: Tank Tests of a Model of the NC l?lying-Boat Hull - N.A.C.A. Model 44. T.N. HO. 566, NACA;1936.

Allison, John M.: Tank Tests of a Model of th~ HullOf the Navy PB-1 Flying Boat - N.A.CCA* Model 52.T.N. No. 576.,NACA, 1936. -— .—

Dawson, John R.,.and Truscott, Starr: A General TankTest of a Model of the Hull of the British SingaporeIIC Flying Boat. T.It.~0. 580, NACA, 1936. ——

Ward, Kenneth E.: Hydrodynamic Tests in the N.A.C.A.Tank of a Model of the Hull of the Short CalcuttaFlying Boat. T.N. No. 590, NAGA, 1937.

Allison, John M6: Tank Tests of a Model of One Hullof the Savofa S-55-X Flying Boat.- N.A.C.A. Model46. T.N. No. 635, NACA, 1938.

Dawson, John R.: A General Tank Test of a Model ofthe Hull of the T3M-Z Flying Boat Including aSpecial Working Chart for the Determination of HullPerformance. T.N. No. 681, NACA, 1938.

Truscott, Starr, parkinson, J. B. Ebert, John W,, JrO,and Valentine, E. Floyd: Hydrodynamic and Aero-dynamic Tests of Models of Flying-Boat Hulls De-signed for LOW Aerodynamic Drag - N.A,C.A. Models

—

74, 74-A, and 75. T,N, NO. 668, NACA, 1938.L

Truscott; Starr: The Enlarged N.A,C.A. Tank, andSome of Its Work. T.M. No. 918, NACA, 1939.

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<SES5KSttß TITLE: Hydrodynamlc Te3ta of a 1/lO-Size Model of the Hull of the Latecoere 521 Flying

Boat - NACA Model 83 AUTHORS): Olson, Roland K.; Lina, Lindsay J. ORIGINATING AGENCY:National Advisory Committee for Aeronautics, Washington, D. C. PUBLISHED BY: (Same)

ATT0- 8822

"(None)

Dec '41 UMOUAOI

Eng. _22_ lUusnuTtow

photos, table, prraphs

Mo^-t

Lines and offsets of hull were obtained from manufacturer; however, form of stub-wing stabilizers was not furnished and model was tested without them. Model was tested free to trim at design initial load (initial load coefficient of 0.428) and by general method at load coefficient from 0.025 to 0.6. Spray charac- teristics of model are good. Form of bow would be particularly desirable for rough water use. Interference of afterbody and tall extension is excessive enough to cause very high resistance at high speeds. Violent vertical Instability is present at trims of 4° and 6° with light loads and high speeds.

DISTRIBUTION: Request copies of this report only from Originating Agency DIVISION: Water-Borne Aircraft (21) SECTION: Stability and Control (6)

ATI SHEET NO.: R-21-6 -5 Air Documontt Diviiion, Intolllgonco Ooportmont

Air Malarial Command

SUBJECT HEADINGS: Flying boats - Hydrodynamlc stability (41754.5); boats - Spray characteristics (41760)

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