On
the
subject of using fuel as a coolant - in the FA-18 Hornet the
fuel is
used to
cool the accessory drive units on each engine (generator, hyd
pump,
fuel
pump). From there the fuel is circulated through the relatively
small
and
thin internal wing tanks to radiate the gained heat.
Unfortunately,
I
can't
think of a good use for this concept in our homebuilt aircraft.
:(
Mike Amos
I tried circulating the return fuel from the pressure regulator
through
a
heat exchanger in the oil pan to help cool it. Worked, but not
enough
volume of fuel to make it worth while (oil temp down 2 degrees at
cruise).
The temperature rise in my wet wing fuel tanks was not even
measurable.
I
may revisit the idea with a separate higher volume pump. The idea
of
"drag
free" oil cooling really appeals to me. A clean airplane has about
30%
drag
in cooling (does not apply to you jet jocks) so if oil cooling is
33% of
cooling on a rotary, that means a potential of 10% drag reduction.
Aero
engineers would sell their mothers for 10% of drag.
Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com
O.K. This is from memory which in my case can be somewhat cloudy. But
I
remember the F-16 having a Heat exchanger in the fuel system. It used
fuel
to cool either engine oil or hydraulic fluid. I don't remember which for
sure. Could a heat exchanger be put in a main fuel tank. Or maybe it
could
be installed in some sort of sump or header tank to keep it immersed in
fuel? Would this work better than having the heat exchanger in the hot
oil
pan?
James Phillips
In the tank would work but not any better than in the pan and it adds more
long high pressure oil lines to the system. The sump tank is a bad idea
because it does not give anywhere for the heat to go.
Yes, the F16 and every airliner you ever flew on uses the fuel to cool the
hydralic system.
Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com
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