8/3/2019 1942 - 1697

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AU GU S T 1 3T H, 1 9 4 2 FLIGHT 175

A V R O L A N C A S T E R

The Lancaster is characterised by underslung engines, a fairly thin wing, and twin rudders.

Length -Span - -

t he Br i t i sh a i r c ra f t i ndus t r y , h a s g r a d u a t e d t o h i sp re se n t pos i t i on th rough thehard school of worksm a n a g e r s h i p , a n d h a s r e t a ine d h i s i n s i s t e nc e upo nt h e m a n u f a c t u r i n g a s p e c tb e in g k e p t p r o m i n e n t l y i nmind du r ing the de s igns t a ge .I t w ou ld be f a i r t o sa ytha t t he La nc a s t e r w a s v i r t ua l ly de s igne d a round ac h a s s i s ' ' f o r m e d h y t h eb o m b b a y roof, t he w ingc e n t re se c t ion , a n d the un derc arr iag es. T he f loor i sof grea t length to aecorr .mo-d a t e t h e b o m b l o a d , w h i c hma y inc lude the l a rge s t bomb v i sua l ised a t pr ese nt , a nd is s lung from thespars of th e wing cent re sec t io n , sotha t t he se tw o f r a me s fo rm the fo re -a nd -a f t a nd t r a ns ve r se l imbs o f t hec ross - sha pe d c ha ss i s w h ic h i s t heba c kbone o f t he w ho le a i r c ra f t .* In it s t u rn , t he ma in s t ru c tu re o f

^ - the roo f o f t he bomb ba y a re tw oe x t r u d e d d o u b l e - c h a n n el o r " p i "se c t ions . I f one a do p t s t he l a t t e rn a m e , t h e a r r a n g e m e n t c a n b e v i s u a l ised as the Greek le t te r p i ly ing on i t ss ide ( see ske t c he s ) . Th i s e x t ru s ion i sa very f ine p iece of work , and pract i c a l ly no ma c h in ing i s ne c e ssa ry , e v e nthe sha l low- recesses for the sk inp la t ing o f t h e fu se l a ge be ing fo rm e ddur ing the e x t ru s io n p roc e ss , a n d no tb y s u b s e q u e n t m a c h i n i n g .T h e C e n t r e S e c t i o n

The c e n t re se c t ion o f t he w ing i sof e qua l ly s imp le c on s t ruc t ion . Th es p a r s a r e , s o m e h o w , r e m i n i s c e n t o fthe o ld da ys of w oo de n a i r c ra f t , w h e ni t w a s c o m m o n p r a c t i c e t o g o ug e o u tthe spa r f la nges o n sp ind le ma c h in e s .In t h e La nc a s t e r t he s e f la nges a rel i gh t a l l oy c ha nn e l s of im pre ss ived i m e n s i o n s , a n d t h e m a n n e r o f u s i n gt h e m is i n t e r e s t i n g . I n s t e a d ofp l a c i n g t h e c h a n n e l s e c t i o n s w i t h t h e i r

69ft. 6in.- 102ft. Height - - 20ft. 6inW eigh t - - 60,000 lb

Fuselage construction and the " pi-section " longeron of the bomb bay.

b a c k s t o w a r d s t h e w i n gc ove r in g , t he y l i e on th e i rs i des , a nd the so l id she e tspa r w e b p l a t i ng i s r i ve t e dto th e c losed s ides of th ec ha n ne l s . I t w i l l be se e nt h a t t h i s a r r a n g e m e n tg r e a t l y fa ci li ta te s t hea t t a c h m e n t ( b y b o l t i n g ) o fo t h e r s t r u c t u r e m e m b e r s ,e q u i p m e n t , e t c .The s imi l a r i t y t o w oodc ons t ruc t ion goe s f a r the r .Th e spa r f l ange c ha n ne l s a t er o u t e d o u t i n m u c h t h es a m e w a y , a n d t h e t a p e r i ath e sp ar f langes from cen trese c t ion to w ing t i p s i sob ta in e d by mi l l i ng a w a ypor t i ons o f t he c ha nn e l w a l l s . Ce n t re -sec t ion r ibs a re in the form of N-g i rde r s , t he l imbs o l t he N be ings im p le c ha n ne l s , w i th t he f re e e dge stu r ne d in w a r ds so t ha t t he re i s on lya f a i r l y na r ro w ga p l e ft b e tw e e nth e m . Suc h se c t ions c a n be ve rys imp ly jo ine d toge the r by p l a in

gusse t p l a t e s a nd r ive t s .U s e of C a s t i n g s

W h e n i t c a m e t o a t t a c h i n g t h e u n de rc a r r i a ge s t o t he e nds o f t he c e n t re -se c t ion f ron t spa r s t he me ta l foun de r sc a me to t he a id o f t he A vro de s igne r s .T h e N o r t h e r n A l u m i n iu m C o m p a n yp r o d u c e d s o m e r a t h e r r e m a r k a b l ec a s t ings i n a ne w l igh t a l l oy , a ndt h e s e , w i t h a m i n i m u m of m a c h i n i n go f f a c e s fo r t he p i c k -up po in t s , supp o r t t h e u n d e r c a r r i a g e u n i t s a n d t h einne r e ng ine s . To ha v e bu i l t up the sel a r g e b r a c k e t s w o u l d h a v e e n t a i l e d av e r y c o m p l i c a t e d a n d h e a v y s t r u c t u r e .The c a s t i ngs a re l i gh t a nd the j obg re a t ly s imp l i f i e d .R e f e r e n c e h a s b e e n m a d e t o t h eg i rde r r i b s e f t he w ing c e n t re se c t ion .I n t h e o u t e r w i n g p o r t i o n s t h e r i b sha ve L-se c t ion f la nges a n d sh e e tw e b s , w i t h s p a n w i s e s t r i n g e r s b r a c i n gthe m l a t e ra l l y a nd s t i f f e n ing the sk inc ove r in g . Th e l e a d in g e dge i s a