Essential and Dispensible WW2 aircraft.

guy wrote:

Responding late, but a few points:

On 18 Oct, 00:51, Dan Nafe wrote:
In article . com,

Eunometic wrote:
The modification would have required a lengtened nose to and
additional
radiator area to deal with the extra head and to dump heat from the
intercooler.

Liquid cooling an aircraft engine is like air cooling a submarine
engine...

;-

What has liquid cooled engines to do with intercoolers?
Nothing. Highly supercharged engines (Pressure Ratio of more than 3.0)
really benefit from removing as much of the heat that's generated by
compressing that air as possible, though. Some airplanes used cold air
(P-38, P-47, B-17, B-24, B-29) to do that, some (2 Stage Merlin) used
liquid.

And if liquid cooled engines are so bad why did every airforce want
liquid cooled engines for their fighters in WW2 (except the USN)?

Well, a couple or 3 reasons. With a smaller frontal area, it was felt that
an inline engine would be more streamlined, reducing drag.
It was also thought that a liquid cooled engine would have better heat
rejection - you just wouldn't be able to run an air-cooled engine at high
power due to insufficient cooling.
and last, but not least, fashion happens as much in Aviation as it does
anywhere else. Pointy airplanes look cool, so people like to design pointy
airplanes.

As it turns out, you lose most, if not all of the frontal area advantages of
a liquid cooled engine because you need to have radiators sticking out in
the breeze to keep the coolant temperature within tolerable limits.
As an example, consider a comparison between the aircooled P-47, and it's
liquid cooled British equivalents, the Typhoon and Tempest. They have
almost the same frontal area. In the case of the Typhoon and Tempest, half
of it is radiators.
It's possible to build low drag cooling systems, like that of the P-51
(Especially the B models and up), but it requires long ducting to act as a
diffuser, a large radiator that, because of the ducting, will have to be
buried in the structure, and a converging outlet to accelerate the heated
air.
The idea that an air-cooled engine couldn't get rid of heat fast enough was
based on the idea that you couldn't put enough fin area on a cylinder to
get rid of the heat. In the U.S., both Wright and Pratt & Whitney
developed methods of making fins thinner and closer together, and with
special shapes,to give more cooling area.

--
Pete Stickney
Without data, all you have is an opinion