This does "sound right" but the few studies I've seen showing the
exit air temp on air cooled engines was very close to what water cooled engines
have been.
My delta T air temps on my 3.75" rads is 70 - 80 degrees F at
cruise, much higher than most people assume. This is THE reason I
advocate thick rads, at least on 200 mph class aircraft.
Tracy
The amount of heat rejected is very similiar, however the delta-T
available to drive the heat into the air is less for the Rotary than for the
air cooled engine because of the temperature limitations of the water cooling
circuit. Therefore we cannot heat the air as hot, and therefore need more air
than for a direct air-cooled engine.
Bill Schertz
KIS Cruiser # 4045
----- Original Message -----
Sent: Wednesday, April 06, 2005 9:43
PM
Subject: [FlyRotary] Re: rule of thumb
and RV-3 sizes- was Cooling Inlet Areas/Bernie's RV9
snip
I mentioned that on the
other list, but I was dismissed as " you can't compare aircooled engines
with a rotary".
I don't think there is a
great difference on the amout of cooling necessary, as the efficiency of
both engines are fairly close. So some heat goes out the exhaust and the
rest has to be cooled. For sure you need different ducting, but the
amount of heat energy should be about the same and you want to get rid of
it with the least drag, either way.
snip[