Stretching WW2 Designs

On Sun, 22 Aug 2004 09:25:27 -0400, "Lawrence Dillard"
wrote:

Recall that the inline Allison-powered P-40, developed from a radial-powered
predecessor, benefitted from such an aft-fuselage stretch, improving its
fineness ratio, allowing for drag-reduction at the tailfin-rudder interface,
and even allowing for fitment of a low-pressure variant of the RR Merlin.
Had the stretched P-40 been given the Merlin 20 series engine, it could have
become a serious high-altitude competitor.

The P-40F and L had the Merlin 20, and the L the stretched fuselage.
I suspect you mean the Merlin 60 series, but as the first Packard
Merlin 60-series scale production didn't begin until the second half
of 1943, I can't see why the better Mustang airframe would have been
passed over in favour of what everybody was calling an obselete
airframe by 1942. The Merlin 20-engined P40's were out-performed by
the Merlin 45-engined Spitfire V as interceptors to start with, so it
made no sense to miss out on Spitfire IX/VIII production to use the
engines concerned to produce Merlin 60-engined P-40s.

Ballasting was not usually a good solution. In the Spitfire, for example,
ballasting was not very efficient when used in conjunction with the wider
and heavier Griffons, rendering tricky handling and at least one
test-establishment evaluation calling for cessation of production of Griffon
variants for that reason.

That was an early variant of the F.21, where the evaluation
establishment went beyond their remit, and where in any case the
problem was fixed. Meanwhile, two Griffon-engined versions had
previously gone into service, the first (the Mk XII) about eighteen
months beforehand, and the second (the Mk XIV) with great success,
being called the best single-engined fighter tested by the AFDU to
that point.

Gavin Bailey

--

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