"Corky Scott" wrote in message
...
On Tue, 15 Jul 2003 11:54:37 -0600, "Bill Daniels"
wrote:



Another area where I would like to see some experimental data is the
"Radiator Ramjet" (just to pick a controversial term) where the radiator
is
in a tube and the heated air exits the rear of the tube at a higher
velocity
than the cool air entering the front of the tube, theoretically producing
a
small amount of thrust that offsets the drag of the radiator.

Bill Daniels
"Jay" wrote in message
. com...
Hi Bill,

You don't need experiental data for this Bill, you just described the
P-51 Mustang cooling system.

However, even with three heat exchangers putting out heat into the
exhaust air and a 1400 horsepower engine producing the heat, the
Mustang never actually managed to get a net thrust out of the system.
In addition, the point where the cooling system was ***ALMOST***
equalling drag was a very specific speed and altitude. I forget the
exact height but it was above 20,000 feet and the speed was over 300
mph. Only under those circumstances did the power being generated and
the speed being flown produce the necessary heat to accelerate the
exhaust air flow to nearly cancel out cooling drag. By the way, most
of the cooling systems did this to some fashion, but the Mustang was
the first to actually design the cooling system to really benefit from
it. This concept was researched and written up by a British
aerodynamicist by the name of Meridith, and the produced thrust became
known as the "Meridith Effect".

North American designed the Mustang's system using the best
aerodynamicists available at the time and with virtually unlimited
resources to manufacture the kind of heat exchangers that would work
in this environment.

Yeah, North American did well with the Mustang given that it was just old
"slide rule" engineers one generation ahead of me working on it. I imagine
the kids these days using Computational Fluid Dynamics programs and modern
materials could improve on the Meridith Effect - maybe a lot.

I don't want to get too far form the original posters idea on skin
radiators. That idea is worth some experiments too.

Bill Daniels