----- Original Message -----

To: Rotary motors in aircraft

Sent: Thursday, April 07, 2005 2:22 PM

Subject: [FlyRotary] Re: rule of thumb and RV-3 sizes- was Cooling Inlet

>On Thu, 07 Apr 2005 12:06:29 -0400 Tracy Crook <lors01@msn.com> wrote.
>MessageThis 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.

From: echristley

This is completely logical if you consider the extremely small surface area
available to transfer heat on the cylinderhead fins compared to the surface
area on even a small radiator.


I agree.  To take this even further, an *optimized* water cooled installation will use fewer CFM to cool a given number of BTUs (and have less drag) than an aircooled engine.  The P-51 would probably not been able to escort bombers all the way to Germany and back if it had an air cooled engine (all other factors remaining the same).

 

Tracy