Re: REFLECTOR: Pictures of the air intake on my bird

["David M Parrish" <dmp@radbsd.mcg.edu>]

From:           	"Bob Kuc" <kucb@ix.netcom.com>


> Think of a straw attached to the side of the plane.   Wind will go through
> that with very little drag.  Put in a flap with an actuator.  I would think
> that if you put in a temp probe in  the plenum at the hottest point, and
> attach this to a microprocessor.  At a certain temp rang, have a servo open

For aerodynamic reasons, it's better to have the flap on the outlet 
side than the inlet side, since you want as smooth as possible 
airflow on the inlet without all the distubances that just about any 
flap arrangement would produce.

Tony Bengellis suggested having a variable outlet flap controlled by 
the thermostat from a VW beetle, though I've heard the P-51 had 
both manual and thermostatic control of it's flap, and pilots 
routinely used only the manual system.

The best way is to have the cooling inlets just big enough for good 
enough cooling under worst case conditions. (Deciding what is 
your worst case is the fun part.) That reduces the frontal drag. 
Then, when you don't need that much cooling, use an outlet flap to 
reduce flow through the system. (Reducing drag by reducing 
internal flow losses.)

---
David Parrish