Re: Sleeve-valve engines

From:         julian@gatwick.sgp.slb.com
Date:         07 Mar 94 15:12:38 PST
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Bob Wohlsen wondered about sleve-valve engines......

A recent copy of the magazine Takeoff had an article about
the Bristol Brabazon. I pretty sure it said that the original
engines for this were sleeve valved. 

A bit of backround on this beastie. The Brabazon was developed
at Filton just after the war as non-stop Atlantic flier. Up to 
that time I believe aircraft refueled at Gander, Shannon or
Prestwick. The Brabazon was a monster, mid fuselage diameter
was about 18ft and it was the biggest thing around at the time
(early fifties). Inside it was laid out like a liner with bars,
a cinema, restaurant, 3 decks and sleeping areas. There were very
few passengers, the whole emphasis being on luxury. A similar sized
aircraft today would hold about 300 people!

The engines were 8 sleeve-valved (rotaries?) paired to drive
four sets of 3 bladed contra-rotating propellors. Later they
went for the Proteus Turbo-prop engine. These were paired to
drive four sets of 4 bladed contra-rotating propellors. The use
of the Proteus upped the speed from about 200mph to about 300mph
and improved the rather poor power to weight ratio.

Weight was always a problem so the airframe was shaved to the 
minimum. There was a gust alleviation system to save the wings 
snapping. Wing span was immense and the wings were fat. A mechanic
could stand up inside and walk from the fuselage to the engine bays. 
 
BOAC were the intended customer but they never expressed much
interest preferring the Boeing products though BEA nearly had
some. Main problem was that killed it was a lack of orders, speed
and the few passengers it could carry. The arrival of the smaller
faster jets Comets, 707, DC8 really finished it off. No airframes
exist today.

Julian Fitzherbert
julian@gatwick.sgp.slb.com