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SEPTEMBER *2OTH, 1945

FLIGHT

3*5

LEADING PARTICULARS

ASPIRATION

Type

..

..

. . Pressure liquid-cooled, in-line Go deg.

No. of cylinders

Bore and stroke U n i t c a p a c i t y T o t a l s w e p t v o l u m e R e d u c t i o n g e a r R o t a t i o n . . * . Airscrew shaft size

. . 1 2 , a r r a n g e d i n t w o m o n o b l o c b a n k s o f s i x w i t h d e t a c h a b l e h e a d s . .. Coin, x 6.6in. .. 186.6 cu. in. . . 2 , 2 3 9 c u - m - ( 3 6 - 7 l i t r e s ) . , . D i r e c t s p u r g e a r : R a t i o : 0 . 5 1 0 2 : 1 . . . L e f t - h a n d t r a c t o r . ... No. 5 S.B.A.C. Standard.

Valve, type

No. of valves/cylinder Supercharger

Carburettor

Magneto Plug positions

Firing order

..

Ignition timing . .

, . P o p p e t e x h a u s t valves sodium c o o l e d . . . F o u r , q u a d r a n t l y d i s p o s e d . . . C e n t r i f u g a l t w o - s p e e d t w o - s t a g e w i t h i n t e r - c o o l e r . . . R o l l s - R o y c e B e n d i x - S t r o m b e r g p r e s - s u r e i n j e c t i o n t y p e 9 T / 4 0 / 1 t r i p l e - e n t r y u p - d r a u g h t . . . B . T . H . C . S . H . 1 2 - 1 2 5 / 3 d u p l e x t y p e w i t h i n t e g r a l d i s t r i b u t o r s . , . T w o / c y l . d i a m e t r i c a l l y o p p o s i t e a n d r a d i a l l y d i s p o s e d o n e e a c h t o i n l e t a n d e x h a u s t s i d e s . , . ( P = p o r t ; S = s t a r b o a r d ) i S , 4 P , 3 S , 2 P , 5 S , i P , 6 S , 3 P , 4 S , 5 P , 2S,6P. , . F u l l y a d v a n c e d : I n l e t p l u g s 4 5 d e g . b e f o r e T . D . C . E x h a u s t p l u g s 5 1 d e g . b e f o r e T . D . C . F u l l y r e t a r d e d : I n l e t p l u g s 1 0 d e g . b e f o r e T . D . C . E x h a u s t 16 deg. before T.D.C. p l u g s

Crankshaft type

. Counterbalanced six throw. • BEARINGS

M a i n b e a r i n g d i a m e M a i n b e a r i n g a r e a s ters B i g - e n d d i a m e t e r B i g - e n d a r e a s C e n t r e , 5 . 4 5 s q . i n . E n d s a n d i n t e r s , 5 . 1 2 s q . i n . F q r k r o d s , 3 . 1 0 m . ; p l a i n r o d s , 3 . 7 7 3 m . F o r k r o d s , 6 . 2 8 s q . i n . ; p l a i n r o d s , 2.61 sq. in. G u d g e o n d i a m e t e r 1.50m. T o t a l area g u d g e o n .. bearing .. .. 6 . 8 3 s q . in. R o d / g u d g e o n b e a r i n g a r e a 2 . 9 7 6 s q . i n . P i s t o n / g u d g e o n b e a r i n g a r e a . . . . . . 3 . 8 5 4 s q . i n . C o n . r o d l e n g t h , c e n t r e t o ' . . 1 0 . 6 5 m . centre ..

Ratio of con.rod length

to stroke

..

. . 1.614 : i ^ = 3.228.

M a x Cam base circledia . a n g u l a r i t ) ' o f c o n . r o d .

18 deg. 1.150m.

C a m m a j o r a x i s l e n g t h . . V a l v e l i f t I . 5 3 o 8 i n . 0 . 5 7 0 .... m .

WEIGHT

P o w e r / w e i g h t r a t i o . . 0 . 9 4 1 I b . / b . h . p . W e i g h t / s q . i n . p i s t o n a r e a 6 . 1 5 9 l b - M a x . m e a n p i s t o n s p e e d 3 , 0 2 5 f t . / m i n . W e i g h t o f p i s t o n a n d r o d a s s ' y / c y l . " . . 1 2 . 2 3 l b . ..

Valve timing I n l e t p o r t t h r o a t ) . . I n l e t o p e n s 2 4 d e g . b e f o r e T . D . C . ; c l o s e s 4 4 d e g . a f t e r B . D . C . E x h a u s t o p e n s 6 4 d e g . b e f o r e C . D . C . ; c l o s e s 4 d e g . a f t e r T . D . C . (valve area 5-54 sq.in./cyl. Exhaust port area (valve

t h r o a t ) . . 4 . 1 2 s q . i n . / c y l . P i s t o n a r e a t o i n l e t v a l v e

area ratio

..

Piston area to exhaust

valve area ratio

..

    • 5.103

      : 1

    • 6.867

      :!•

Ratio of piston area to

frontal area

..

..

C y l i n d e r c o m p r e s s i o n r a t i o M a x . i n t e r n a l c o m p r e s - s i o n r a t i o o f b l o w e r I m p e l l e r d i a m e t e r s M . S . g e a r r a t i o . . F . S . g e a r r a t i o E q u i v a l e n t t i p s p e e d s

Eye area of 1st impeller

Rich mixture ratio Weak mixture ratio

0.298 : 1. 6:1.

5-3:1- 1 s t s t a g e , 1 3 . 4 m . ; 2 n d s t a g e , 1 1 . 3 m 5 . 8 4 : 1 . 7-5S: 1. M . S . c r u i s i n g , 1,071 ft./sec.; M.S m a x . p o w e r , 1 , 2 2 8 f t . / s e c . F . S . c r u i s i n g , 1 , 3 9 1 f t . / s e c : ; m a x . p o w e r , 1 , 5 9 4 f t . / s e c . 5 6 . 1 s q . i n . f r e e , 4 0 . 5 s q . i n . , s t r i c t e d b y t a i l b e a r i n g s u p p o r t . 1 1 : 1 b y w e i g h t . 1 4 : 1 b y w e i g h t . F . S . r e -

Max, boost pressure Max. cruising boost pres-

POWER 21 Ib./sq.in.

7 lb./sq.in. sure M a x . b . h . p . M a x . r . p . m . C r u i s e r . p . m . M a x . b . m . e . p . 2,220. 2,750- A l t i t u d e t o w h i c h 1 a t a . 2 , 4 0 0 . 2 8 6 l b . / s q . i n .

manifold pressure is maintained P o w e r / c u . i n . s w e p t 39,500ft. in F.S.gear. v o l u m e Power/litre . . . . , . . . . P o w e r / s q . i n . p i s t o n a r e a 6 . 5 4 h . p . P o w e r / s q . f t . f r o n t a l a r e a 2 8 1 h . p . P o w e r r a t i o / s q . i n . p i s t o n t o s q . i n . f r o n t a l . . . . ' . . 3 . 3 5 : 1 . 0 . 9 9 2 h . p . 6 0 . 5 h . p . area ' area

AUXILIARY DRIVES A u x i l i a r y d r i v e s p e e d s ( r a t i o r e l a t i v e t o c r a n k s h a f t ) T a c h o 0.984 m e t e r 0 . 2 5 0 Gearbox input 1 . 1 ( A c c e s s o r y d r i v e h y d r a u l i c p u m p , : : .. .. .. faces: electric g e n e r a t o r , a i r c o m p r e s s o r , v a c u u m p u m p ) .

Magneto C.S.U Fuel pump

Oil pumps

E n g i n e c o o l a n t p u m p . . I n t e r - c o o l e r pump c o o l a n t

Starter Type of starter

    • 0.50

      : 1.

    • 0.82

      : 1.

    • 0.887

      : 1.

    • 0.984

      : 1.

1-793 : i-

1.799 : i- 1 : 1.

Coffman combustion typeL5.

Thevery high output of the engine would not be pos- sible without the two-speed two-stage supercharger which, ait.hough of greater capacity, seems to be smaller than that of the equivalent Merlin; nevertheless, a price of no less than 600 h.p. is paid in driving the supercharger and, even more amazing, this power is transmitted through relatively small friction clutches in the speed change unit. A driving frheel on thespring drive coupling at therear of the crank- shaft meshes with a hollow layshaft in the change-speed unit, this layshaft housing a stationary piston and sliding

gears can both be in constant mesh with the impeller pinions.

Automatic Blower Gear Change

If the aircraft climbs into an altitude range where F.S. gear is required, the change of speed is effected automatic- ally by a selector mechanism which actuates a piston valve so that oil delivered by the special pump in the crankcase

is directed to

piston.

The

the appropriate pressure exerted

side of the change-speed unit against the piston reacts on

cylinder assembly.

Mounted on the layshaft

of

clutch

plates

and driving

rings

on each

side

member

in which

are pivoted

six

fly-weights

;

are a series of a driving the clutches

on the crankshaft side of the central weights are for supercharge drive (F.S.), whilst those on the impeller <! the weights are for moderate supercharge (M.S.),

full side the

the cylinder causing it to move, and by so the fly-weights away from the M.S. clutches F.S. clutches; as the weights move beyond plane centrifugal force again takes hold and

to engage the drive through

F.S. clutches which the high-speed F.S.

thereupon gear.

doing, push towards the the neutral forces them

transmit

the

respective clutches transmitting the drive which mesh with pinions on the impeller

through shaft.

gears

When, for example, M.S. drive is in operation, the fly- Weights are held inclined rearwards by centrifugal force t>;engage the clutch plates of the M.S. gear, and, asthe i'S. clutches aredisengaged anddoing no work th,e driving

The automatic selector mechanism which effects the blower speed change comprises an aneroid capsule which operates a micro-switch to open a valve in the aircraft's

air of to

supply, and so pass compressed air to a ram on the end

the

piston valve

the

change-speed

which unit.

directs the distribution of oil However, the pilot is provided

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