?;AT ICXAL A3Vf SC3.Y CGDJITTZZ FOR AERONAUTICS.

TECHNICAL I,IE3'.OMPZL?,i 1:C. 405.

STSECTUML DZTAILS FRGi 1926 PARIS AERC) SALON+ * 3 y W. Rethel .

The c r i t i c i s n of Gerzqan s p e c i a l i s t s on the t e n t h P a r i s

Aero Salon is , i n peileral: "Nothing new i n air-olanes t o b e seen."

For rea.so:is e a s i l y understood, $he F ~ e n c h ~vnuld l:a r d l y exh ib i t

t h e i r most ixodern m i l i t a r y a i r p l a n e s . The French c o m e r c i a l

a i r p l a n e s shown i n the sa lon a r e a l r eady fir ell known i n a i r t r a f -

f i c . Since t h e German corx-?ercial a i r p l a n e s have been f a r b e t t e r

developed, du.e to g r e a t e r t echn ica l requirements, t h e juagment

of t h e p ro fess iona l world "?Tothing newt' is even here thoroughly

j u s t i f i e d .

Althouyh t h e o t h e r na t ions ( ~ n ~ l i s h , Dutch, I t a l i a n , and

~ z e c h s ) o f f e r noth in3 s p e c i a l , it may never the less be of i n t e r -

e s t t o d i scuss a few s t r u c t u r a l d e t a i l s , i n order t o l e a r n t h e

tendencies of foreig-1 a i r p l a n e cons t ruc t ion .

Very zany Frensh g u r s u i t an6 combat a i r p l a n e s a r e high-wiiig

monoplanes. This i s Cue t o t h e good v i s i b i l i t y of t h i s type.

Since i t i s very d i f f i c u l t t o o r o t e c t the wings of high-wing

monoplanes a g a i n s t d i s t o r t ion, some French cons t ruc to r s employ

a -:lethod of wing t r u s s i n g t~ l i i ch is d i s l i k e d i n Germany, in order

t o amel iora te t h i s disadvantage. The landing year is included

i n t h i s winq t r u s s i n g , so t h a t t h e landing-gear a x l e o r i t s f a i r - ,

*"Kon~truc? ive ,~Einzelhe i te . r? a u s dm P a r i s e r Aero-Salon." Fron " Z e i t s c h r i f t f u r Flugtechnik uild Votor lu f t sch i f f a h r t ," February 14, 1927, p-o. 53-57.

incr 'oecoi~es a p a r t of the su3;3ortiny s t r u c t u r e . The encleavor

t o p l a c e t h e lower cernSer of t h e vring t r u s s i n g as low a s possi-

b l e is noted both i n the high-wing mono->alanes and i n the braced

o r s e n i c ? n t i l e v e r 3 i3 lanes . Fig. 1. shows e igh t d i f f e r e n t a i r -

o lanes lr!i t h t h i s kind; of wing t r u s s i ~ g . The upper and lower men-!-

S e r s of the t r u s s a r e drawn heavier f o r t h e sake of c l ea rness .

This c e l l s t r u c t u r e i s accompanied, horxrever, by a g r e a t

c o ~ n l i c a t i o n of tile landing year , so t h a t i t is doubt fu l as t o

whether i t is advantaqeous f o r a l l a i r q l a n e s . I t is very well

s u i t e d t o small a i r ~ l a n e s , such a s t h e Nieuport-Dc!.age l 'Jocke~r,i '

s i n c e t h e s u s ~ e n s i o n s t r u t is, here q u i t e s t eep an2 can Se car-

r ied. n 2 s t t h e wheels t o t h e junct ion n o i n t s of t h e l and ing gear .

The l o v e r <?m7oer i s a l s o s u i t e d t o l a r g e hiqh-wing s e a ~ l a n e s ,

l i k e t?le " 9 e ~ s o n , '' s ince i t a f f o r d s a convenient s u p ~ o r t f o r t h e

l a t e r a l f l - o ~ t s : , vl;icln it i s ot'nernrise d i f f i c u l t t o obta in iil

t?is tyoe of seaplane.

Bgchereau and De iIurea-il-x u s e e nlmber of s t r u t s with very

expensive j u i ~ c t i o n s arid shock a'asorbers, iil order t o ca r ry the

t r u s s i n g qast the i'irlieels through the l a n d i n 5 gear. 3reguet has

d e v e l o ~ e d a good sprincj- 1-rheel f o r the same purnose, so t h a t iic

can join the t r u s s i n g t . i r e c t l y t o fhe r i g i d a r l e . Levasseur

d i spenses --rith the a x l e and ~iri-ieel spr ings and l i k e v i s e j o i n s

h i s bracing, which -3asses through t h e lower \:ring, t o the r i g i d

a x l e . This has tke dj.sadva-ntaze, kosrever, t h a t a l l the s t a r t i n g

and lagdingshoc!csare traiisnitted-undzniped t o t h e n ' l . i n ~ c e l 1 ,

I ? . A . C . A . Technical I,lexora.ndu~ 170. 4.55 3

r ~ h i c h nap cause unavoidable i n j u r i e s .

EnCeavors a r e every-where beino: made t o h u r o v e t h e landing-

qear s l~ock a-9sor10ers. The old type of rub'oer shock absorbers

i s now Sut l i t t l e used. T l~e p r e s e ~ t en2ea.vor is t o d i s t r i b u t e

t h e landing shock uniformly between separa te rubber strand-s,

w'nich a . re f a s t ened ind-ependemtly of one another , s o as t o fur-

n i s h s u f f i c i e n t s:>ock a b s o q t i o n , even when one s t r and is rup-

tu red . 36c'nereau l o c a t e s t h e shock absorber i n a ve ry br0a.d

s t r u t (~ig. 2 ) . The s t r u t c a r r i e s f i v e yokes, t o each of which

two s t r a a d s a r e atta.ched both before and- behind. The end.s of

t h e s e t ~ ~ r e n t y s t r a n d s a r e bounc about 3i:is, which a r e a t t ached

t o t h e s t r u t by s u i t a b l e fit2inngs. The l~rhole 2echanisrn i s Tro-

t e c t e d by sheet i ron . The p r i n c i p l e i s good, bu t t h e construc-

t i o n c ? i f f i c u l t , s ince f o r t y a t t a c h ~ e n t s must b e ~ a 6 e f o r each

rlrheel. l!oreo~~er, the separa te s t r ands a r e bound f o r about 2 /3

of t h e i r le-ir;th, 20 t h a t only the remaining f r e e t h i r d of t h e

s?rand c?n s'retch proper ly o r e l s e t h e s t r a n d s s t r e t c h i n s i d e

t h e 1 v h i ~ ~ i i l q , i n 1~~hich case 'they soon become loose. Fokker, i n a

h i s F 'TI, has adopted/s imi lar d e ~ r i c e ( ~ i g . 3 ) , bu t he uses

closed xibber r i n g s , tlms doing amay with t h e bound loops. This

device i s ext rei:r.sl:r sin-~l.e, ::ialcing i t seem s t range t h a t Bechereau

not u s e these r ings , which, having o r ig ina ted i n England, a r e

nor- a l s o be in? ma?-e b y a French f i m - . These r ings , l i k e t h e ca-

b l e s , coilsist of ::?any s r a l l zubber corCs and a r e spun i n t h i s

'i form.

N . A . C.A. T e c k i c a l I" e:xorandu? F ~ . 405 4

7 i i,Aorc?ne-Saaulnier, l i k e BGcherezu, p laces t h e shock absorb-

e r s i n the p ro tec ted s t r u t s , but t h e two t e l e scope tubes each

have one broad yoke t o w3icn t h e ztbove-described rubber r i n g s

a r e a t t ached ke fo re aiid behind.

1 v i l l 5 r i e f l y desc r ibe two types of metal f l o a t s . The

ot l ter form of the B r e v e t rnetal f l o a t i s very s i x i l a r t o t h e

American Glenn 14artin f l o a t : half-round on top, with a somewhat

keel-shaped bottom. aenind t h e s tep , t h e bottom s lopes upward

too f a s t to7-rard the rear . The half-ro7mc?, shane 'nas, f o r sea-

lanes of 200C kg (4400 l b . ) and upvard, t h e advantage, a s com-

ga red ~ i t h r e c t a n y l a r f l o a t s , of not having an unnecessar i ly

l a r g e capaci ty v i t h a high s t e p . The inner s t r u c t u r e of t h e

Breguet f l o a t has, l i k e i t s Arcerican p a t t e r n , a c e n t r a l g i r d e r ,

which u t i l i z e s t h e r~.liole he ight of t h e f l o a t a.n6 thus a f f o r d s

m e a t long i tud ina l ~ - . s ta 'o i l i ty . The bo t toa has i n t e r n a l and t h e

t o p has ex te rna l 1-ongitudina.1 s t i f f e n i n g members- The two

s t r i p s between t h e s e s t i f f e n i n g mem73ers on the top, on the r i g h t

and l e f t of t h e c e n t r a l g i r d e r , a r e b o l t e d t o t h e adjacent

s t r i p s end not r i v e t e d t o t h e t r ansverse frames. Thus t h e f l o a t

i s a c c e s s i b l e throughout i t s ~mhole length , ~ h i c h i s very impor-

t a n t f o r i t s product ion an$- upkeep.

The s i n g l e f l o a t , exhib i ted a t t h e s t and of t h e Avimeta Corfl-

pany, i s ~ i a d e of " a l f e r i u ; ~ " a.nd has about the same shape of t h e

l ~ o t t o m a s the Br-qust f l o a t , but, i t s c r o s s sec t ion i s t rapezoida l

and narrower on top. The t r ansverse frames a r e the re fo re of

1q .A- C . A . Technical Yenorandu~ 110. 405 5

someTx~hat simpler ~ t r u c ? x r e than t h e 3alf-round ones. The f l o a t

has xore nanholes !~hick, togct3er ~ x i t ' n i t s l a r g e s i z e , render

i t very a c c e s s i b l e . I t yas very nea."sly f in i shed .

Fokker e x 2 i j i t s a .;;rell-<bevi310ped a l l - s t e e l t a i l sk id on h i s

CV. The rubber s5ock-absorbinr caSles l i e in the d i r e c t i o n of

t h e s k i d 2nd a r e a t tached t o e y e l e t s i n t h e fuse lage i n such a

way as t o b e e a s i l y exc:hanged. The sk id i s s t e e r a b l e and can be

turned about i t s 1ongi';ubinal a x i s by mea.ns of a l e v e r and ca-

b l e . A t i t s lower end it c a r r i e s a.n exchangea.ble shoe. A lit-

t l e a-bove t h e l a t t e r t h e r e i s at tached a very simple and g r a c t i -

ca.1 e:Tersensy brakc , c o n s i s t i n g of e c1a.w vhich can S e re leased

b y t h e n i l o t by :leans of a c s b l e ( ~ i g . 4 ) . I t is bein,g used on

Dutch m i l i t a r y a.irgl.a.nes.

In c o n t r a d i s t i n c t i o n t o t h e complex s t r u c t u r e of the ,Fokker

sk id , Fis. 5 'sho~:rs t b e p r i n i t i v e Potez sk id . On the r;tnder s i d e

of t h e fuse lage t h e r e a r e two kea r ing- l ike S racke t s f o r receiv-

i n g t h e c ross rod about s h i c h t h e rc'ober cable i s wound. The .

rod i s fasteiled t o t h e b racke t s b y b o l t s . In order t o a.void t h e

t y i n g of knots i n t h e shock-absorbing g o r t i o n of t h e rubber ca-

b l e , t h e l a t t e r i s a t t ached t o t h e p i v o t of the tsil skid .

Fig. 6 skiovrrs a Fokker-Juyiter device f o r the i n s t a l l i n g of

a r a d i a l engine. I t i s made e n t i r e l y of ~ ~ ~ e l d e d s t e e l tubes.

Nine b racke t - l ike p ieces of sheet ;:zeta1 a r e ~velded: t o a s t e e l -

tub ing ring: - and receive t h e main engine-fastening b o l t s . This

r i n g i s braced aga ins t the four fuse lage junct ion p o i n t s by neane

N .A, C . A . Technical 'Fieqorandmq Bo. 4-C5 6

of s i x tubes which a r e :-~elded t o the r i n g a t t h r e e p o i n t s - Thc

r i s i d i t y i s f u r t h 3 r increa-sed by c ross s t r u t s . The fo rk - l ike

connections c o n s i s t of o i e c c s of t 3 i c k shee t s t e c l velded t o

t h e ou t s ide of t h e tubes. The T-relded j o i n t of t h e cross p ieces

i s s t rengthened by :?elding on a star-shaped .piece of shee t

s t e e l . Thc s;rhole assenbly has a very s i n p l e and r i g i d aDpear-

ance and, & ~ . e t o i t s open s t r u c t u r e , a f f o r d s easy access t o t h e

~ r a y e t o s , ca rbure to r s and o i l p u ~ p s .

Fig. 7 slflov~s a Potez-Juqi ter ecgine s u ~ p o r t of sheet dural-

umin. I t is of VerjT sirilple cons t ruc t ion and a f f o r d s s a t i s f a c -

t o ~ y r i g i d i t y v i t h r e l a t i v e l y few r i v e t s . The f r ~ s t u m of a cone

i s formed out of 3-4 Ynrn (0.12-c.16 in. ) sheet dura lunin , which

c a r r i e s , on tlle i ~ n e r s ide of i t s s n a l l end, a r i v e t e d f l ange

on rsr3ich a r e counted t h e n i n e bra.ckets f o r rece iv ing t h e engine

b o l t s . The base of the cone runs out i n t o four arms, t o srhich

a r e r i v e t e d the p ieces which serve f o r the fuselarye at tachments .

The f o u r arms a r e s t rengthened by double ang le s t r i p s r ive ted

t o the outeide. The r i g i d i t y of the arms i s f u r t h e r increased

b y bendinp t h e i r s i d e s so a s t o form r i g h t angles a t the t i p s .

The engine co~vl ing is fas t ened c h i e f l y b y hinge s t r i p s ,

which run the vrhole l eng th of $he c o ~ ~ l i i l g . The hinge s t rFps

a r e joined by running s t e e l wires through then. This getkod w a s

employed by Fokker two years a go, but was suSsequently abandoned,

due t o the exceesive meigkt, s i n c e k e had use6 b rans hinges.

The engine cowling exkib i t ed ha6 'hard-aluminum hinges, which

T- To f a s t e n t h e co7vlin,-, ~ o ' l k e r ~ O I V u ses s i n z l e l u g s about

'! 20 CE ( 7 . 8 7 i n . , a.pnl-t. A t corresl3onding i ~ t e r v a l s the corrl ing

has holes re inforced by k o l 1 . 0 ~ copper r i v e t s . The co~linq i s

secured Sp s t r o x g ? ins sV.,c!r- t k o u ~ , . 3 t h e iups . This :.ietho6. i s

ve ry s i v p l e sncl F72re, but, on nccc.xi12 of $he .oroj e c t i n g lugs ,

does not 9 ~ c s e : l t SO e le~2q-t : a3 agpearar,ce a s t3e hinges.

Tile B r e g ~ e t xetyoc? o x a s - ; e r , i n s %e cowlins 6 i f f e r s from

t h e o r6 i rn ry metkod. The cowlin% c o n s i s t s of s t r i p s of very

t h i n s1:ee-t Cural joined -to.lreths~ ky i n s i d e crimn~lcg. Tke sec-

t i o n s czde from these ~ n e t a l s t r i p s 5ave a nore o r less rectengu-

1 a r s ' i lqe a ~ d % r e ~1rroundec"l by a f langed metal frame. Strong

p e t a l seq2erAts with in~nrarclly be-nt f l ~ n g e s a r e r i v e t e d t o t'ne

f o u r corners of each sec t ion . I f four such cec t ions come to-

ge the r they fori:~ a r ing , which, with i t s fia,nged- edge; ' is held

ir, 2 cu-o-shs~ed socket s t t a c h e d tc! t h e fr?rne~ivork~ of t"le fuse-

l a ~ e . The fl.ange?. erJ,:::es of t h e segxexts are ~ r e s ~ e d i r t o the

socket by a ~va.s'ller aiid nut . Fig. 8 slows such a faste:iing - ! s f i t 3

h s l f of the cowling rcrno-ired in order t o give a b e t t e r view of

t h e socket. The seps11-ts ::lay a l s o conc i s t of 1/:2 o r 1 /3 c i r -

c l e s according t o vhere they & r e used. Thn, r e thod is good, b u t

expensive and s z i t e b l e onl-r f o r mass .proG?dction.

The F ia t s in .zle-seater ha s all ex t r e ~ e l y wli-shapec?. en-i;ir,e

covrling behind t h e f r o n t a l ~a.c"iiator, tkie cowling Se ing so c?.ose

t o t'iie cy l indcr S locks t h a t t h e a . i r from the r a d i a t o r cgn es-

cape c s s i l y . The accees ib i l . i t y t o t h e s-oark lugs i s good, .,

s i n s e they p ro j e c t throuzh correspondingly l a r g e openings i n t h e

cowling an6 can be exchanged rvit'nout removing the l a t t e r .

For thc f u s e l a g e f rame~~rork, the so- c a l l e d "1:rood an<. ~ l i r i re"

t ~ e of cons t ruc t ion i s muck. use2 i - n France. In Far;.ila,nls com-

13 e r c i a l a . i rplanes tlnerc a r c severa.1 remarkable exam2les of t h i s

ty-oe of c o n s t r l ~ c t i o n . Brace arires run a c r o s s t h e door o-oenings

f o r c ~ b i n ?nd- baggage room end, In u s i n g the doors, must f i r s t

% e removed by qn e a s i l y o-oerated device. This method i s eza-

ployed even on the most recent oce-engine coinrnercial a i r p l a n e

l ' Ja la i -m,v i n vrhich t h e ca"nin w a l l s curve wdt18~ard. I n order t o

seve room, the upholstered s e a t s r r e crowded i n t o t h e curved

s i d e 1 m . 1 1 ~ ~ so t h a t the wire i n t e r s e c t i o n s i n the cabin -oass

throuyh the upholstery of the inner am.s of the c$ai rs . In or-

d e r t o irmrove the appearartce, the wires a r e mound with lush.

The 17rilole qtmc'cilre c-;ives t h e i;n?ression t h a t t h e necessary

wire '~rac ine : - w a s f i r s t thought of a f t e r t h e cabin eqxipment was

f inished. an6 t h a t t h e chai-rs then had t o be pe r fo ra ted i n order

t o -oass tile wires through them. 1 t car, hard ly be imagined t h a t

a Ger-ian cons t ruc to r would ~ ~ e n t u r e anyth ing of the s o r t .

The fuse lage of the Zieux3ort-Delape q u r s u i t s ing le - sea te r

i s covered witl-i -9ly1~~ood end l i n e n , which gives - good l i n e s an& a

smooth sur face . The a c c e s s i b i l i t y f o r i n s t a l l i n g and r e p a i r i n g

i ~ , he~-ever, yer:r Doer-

Bremet , De I'h:ureaux, azd S. E - C * e x l i i 7 ~ i t l ight-metal s t ruc-

N.A. C .A. Technical lienorardum 1-0. 4'25 9

t u r e s . The j:lnctioxs =f a 3reg~:e-t f u s e l ~ g e c o n s i s t of stamped

lia:7-t-mefel -, f l e ~ g e a.sse:-fbIies. The f ie l6-s 2 r e braced rvith s t e e l

~ r i r e s . The junct ions ~ a k e 3 very 3:ood im~ress l .on b u t a r e ex-

c eedinglp exueneive f o r si??all--scale product ion. The opinion

i s o f t e n expresced t h a t Ereffuet t s a i r p l a n e s a r e d e s i g e d e s ~ e c i -

a l l y f o r It..aFs nrod-dcticn. This a p ~ l i c s only "; h i s f a c t o r y

equipment. -Tit> yood er;-iiiprflent and: mss production, even the

most cori?l.ex v a r t s can '=ie cheaply ma-de.

Tlie S.E. C .It. uses principa1l.y C u r a l tubing f o r the fuse lage

f r z n e ~ ~ ~ c r k and ha.s developed clarcp-shzped pressed p ieces f o r t h e

ju-nctlons. T5e r j r o d ~ ~ c t i o ~ is very expensive, s i n c e a d i f f e r e n t

s t axp in? 12achine x-ust b e made f o r every j l ~ n c t i o n with a d i f f e r -

en t m g l e . There can hard ly b e any ques t ion of mass prod-uction

f o r t h e g iant a i r p l a n e exhi3 i ted . We ques t ion vrhether a. simpl3r

type of junct ion would not serve equal ly ~ v e l l . I n case, t h e

work at the drawing board and i n t h e ~~rorkshop s x c i t e s ad-cniratior,.

Iri contra.st w i t 3 t'llis, t h e fuse lage of 3 e 2,ii'cireaux is very

poor . Tkis f u s e l a r e .- i s l ikewise ma5e of &ural. t ub ing (F ig . 9)

and the junct ions coilsist of e'ncet-met21 s t r i p s , ~which a r e at-

tached t o ?,he fv-selage ~ i r c e r s by aeF2r:s of very sxa2.l screvs and-

in terposed f i l l i n s p ieces . For p e a t c s s a f e t y , t h e y a re a l s o

fa s t ened 5o~:etlier by severa l long r i v e t s . The ends of the d - i a s -

onal bra,cing tubes of t h e f u s e l a g e Tvalls a r e square 8.nd a r e at-

tached t o the junction s t r i p s Sg tz'wzrlar r i v e t s , t he number of

r i v e t s be ing ill 30 proper p r o ~ o r t i o n t o t h e cross s e c t i o n s of

Ii .A. C . A. Teckn ica l_ ll~,.~ora.ndum go. 4-35 1 0

t h e dia,ronal s t r u t s . Tke crude 1vorhxanship i n d i c ~ t e s l i t t l e ex-

per ience .

Tl?e F i z t fuse lage hzs a steel .- tubing f ramemork cons i s t ing

of four 1ong;~erons connected by zigzag diz.gona.1 s t r u t s . The junc-

t i o n s a r e n o t ~ ~ ~ e l d e d , but herd-soldered with s l ceves . Over t3is

s t e e l - tubing f ra.::ewor!c t h e r e is la.id a very neat la t t ice- l~rork of

l i g h t .... mcta.?! ( F i q . .- 1 0 ) . This c o n s i s t s of v e r t i c a l rib-1-ilre xem-

b r r s z.il6- l ior izontel -.e!x'oers which a r e corrugated t o increase

t h e i r r i g i d i t y . The ~ ~ e r t i c a l :~??.e~xbers a r e a t t ached t o t h e longer-

011s 55; ;-'cans of small b r a s k e t s i ~ ~ h i c h a r e soldered t o the s t e e l

1onms:ons ?r.d r i v c t e d t o tlnc : rc r t ica l s t r i p s . This l a t t i c e -

1q:ork is covered :.ith doped linen.

F i a t and 3esson exh ib i t a. ~ ~ i n g .., s t r u c t u r e . This i s a l l -

r e t a l , t h e spa r s bei-nq of s t e e l 3rd tile ribs of d u r a l u i ~ i n . Fig.

11. F ~ O ? ~ S 2 2unctlon of c? F i ~ t spur an& r i S . The spa r c o n s i s t s

of two I?-sha.ped s t r i p s r-it5 t h e i r f l anges r ive ted too;ether.

This produces a f r v c r a b l e tkickening of t h s ma te r i a l a t t h e top

andl Sottom :=r;lere the s t r e s s e s a r e g r e a t e s t . T2e ~~rcbs have tri-

~ngulc2r o-?e-nings 1~?hose edges 2.re Sext inr%rdl: thus fomiing r i g i d

d ia g o - n ~ l braces. The r i b s sre braced g i r d e r s with too and Sot-

tom .i?enbers of square d-v-ral tu'oing, t h e d i f f e r e l ~ t members '3eing

joinzd by i-?ePnS of r ivc ted d-ural junct ion p l ~ . t e s . Evi6ent ly a

good :civeti;_?g xachinz !:as used, a s t h e work i s very nec t . The

r i b s a r e secured t o t h e spars b;r saddle-shaped j ~ ~ n c t i o n ~ l a t e s

~~~ i tk? tubu18r r i v e t s . The r i b s a r e a l s o s t recgthened by s t e e l

I? . A . C .A. Technical F.!emorandum No. crJ5

b r a c e lirires. For t h i s purpose, a l l thz r ib f l anpes e r e d r i l l e d t. 0

a t t h e same ~ o i n t and a s t e e l wire i s 3a.ssed through a l l the

holes . Sriall d i s k s a r e soldered t o t h e - i r e s on each s i d e of

t h e f l ange , so a s t o prevent 2ny l a t e r a l yiel-ding. The vhole

s t r u c t u r e impresses one a s 'naving been c a r e f u l l y thought out.

Besson e x h i b i t s an all-mood s t r u c t u r e i n h i s l a r g e boat

sea.plane. The v ing spa-rs have t h e for?;? of box g i r d e r s with ply-

.-rood ?7e%s. They a r e very narrow and high. The r i b s cons i s t of

f la .caes enti ciia-gonzl Sraces . The f l a n s e s themselves have a U-

s h ~ ~ e d c ross sec t ion and c o n s i s t of two wood s t r i p s and a many-

holed ~ e b . The f langes and diagolials a r e joined by means of

->3lyvrood junct ion p ieces . On every r i b t l iere asre ve ry rf?any

glued j o i n t s , which should be avoided on a seaplane. Tlie s?~i'_ie I

s t r u c t u r a l method i s a l s o eaployed i n t h e t a i l , ah ich i s esqc-

c i a l l y exposed contact with r a t e r .

De fiureaux e x h i b i t s a.3 2s -~ec ia . l ly i n t e r e s t i n g d u r a l u ~ ~ i n

s p a r ( ~ i ~ . 1 2 ) . The webs of t h i s spar a r e meda of t h i n shea t

d u r a l with top and bottom edses bent o u t ~ a r d ? t r i g h t angles .

The webs Ere joined toge the r by inany s;2all S o l t s and d i s t a n c e

tubes . The f l anges of t h i s spa r a r e re inforced t o w r d the mid-

d l e , corres-2onding t o the g r e a t e r s t r e s s e s , i n a ve ry practicczl

rn way. ihe top of the f l ange , a t i t s ou te r end, c o n s i s t s of a U-

s e c t i o n , :?hich, as shorn i n Fig. 12, i s inse r t ed bet~vlreen the

webs, t o vrhich it i s joined 3 % shor t i n t e r v a l s by e n a l l b o l t s

nrith d i s t ance tubes. To~~rard t h e miC-dle, t h e ou te r edges of

N.A. C.A. Technical liiemorandu~;2 KO. 405 12

U-sections a r e so ~ ; i d e t h a t a f l znge s t r i p can be r i v e t e d t o

them, a seconc?. f l ange s t r i p Se ing aC.ic;ed t o tilc rcost s t r e s sed

ort ti on. I n osder t o -2revent any 7.oczl benCi;ig of the cdqes of

t h z s c f l a n g e s t r i p s , the f i r s % s t r i p i s c r i ~ p e d ? r a i n s t - t h e veb.

Tkis f i rm e x h i b i t s a d u r a l r i b , t h e flanges rnd diagonals

c o n s i s t i n g of s ~ . a l l U-sect ions . At t h e junct ions, one U-sect ion

i s inse r t ed i n t h e o the r ~ n d securLd by only a. s i n q l e r i v e t . The

cons t ruc t ion r i v e t e d junct ions not

co~~mensxra t e 1~15th t3.c ret.at i v e l y s t r o n g d iagonals . The t a i l

olccincs exhibi ted by De 14ureaus k?vz a s i rn i le r s t r u c t u r e . It i s

of i n t e r e s t t o c o t 2 th8.t ~ o t tke T7i101e of the hor izon ta l s tz7? i l -

i z e r i s z d j u s t r b l e , b u t only t h e l ead ing edige, by ;?cans of spin-

d l e s .

011 -kine l a r g e comxcrcial a i r p l a z e of t h e S*E*G.M. , t h e f r m e -

l-ork of the c c n t r a l s e c t i o n of t k e 1-ring i s cx~_?osecl. The s ~ a r s ,

l i k e thosc of Junkcrs, c o n s i s t of sevcr:*l f lznges of 6 u r a l t u b i ~ p

j oiiied together b i ~ Ccl icw~ia l - tubes. T3e "unctions q r e l i k e those

of t h e fuscla7;e. - Ti; ribs 2 1 ~ 0 have t h e szme kind of junct iozs

i n sxal le l- d i n c i ~ s i o n s anc'. a r e 81-so e:rpensive t o mice.

r . Trans1a.t ion S-,r Elnight Y. l,-lni?r, Nat ional Advisory Cornciiittee f o r A e r o n ~ u t i c s .

N.A.C .A. Technical Kernorandun? N3.405

Nieuport-Delage

Levasseur Breguet