Re: HS Trident...VC-10 and BOAC

Date:         14 Jul 97 20:27:02 
From: (Darren Rhodes)
Organization: Loughborough University
References:   1 2 3 4
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On 13 Jul 97 01:25:52 , Antoin Daltzn <> wrote:
>The VC10 was also a victim of Rolls-Royce.  The Conway was a good civil
>engine when it came out first on the B707-400 and on a small number of
>DC-8s.  In fact, it was the first commercial turbofan.  However, the
>by-pass ratio was low and Pratt & Whitney soon came out came out with the
>higher by-pass ratio JT3D which was also very reliable for its time.
>Rolls-Royce never responded and even BOAC switched to the JT3D for later
>B707s.  Vickers did not respond either.

The bypass ratio of the Conway was 0.6 and for many years RR believed
this to be a sort of optimum value. Higher bypass ratio values were
thought to increase nacelle drag (larger diameter engine) and also
increase engine mass (larger fan), beyond that of the fuel savings
from a more efficient engine.