John,

Is the 6" tube the only air exit from your cowl?

Bobby

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of John Slade
Sent: Wednesday, May 10, 2006 9:58 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Pusher cooling

 > they are used in the augmentor tube to suck and expel the hot air
from under the cowling.
I think Buly's right. Exhaust augmentation has a big effect on ground
cooling. I have the exhaust letting out into a 6 inch stainless tube
which exits the cowl at the rear. The exhaust pipe stops about 2 inches
short of the end of the tube. All the air expelled has to come through
the NACA, into a plenum, then through the coolers. I  had a fan
installed, but it didn't any measurable difference (probably because it
was just circulating air) so I removed it. Without the fan  my engine
stabilizes at about 195F during prolonged taxiing on a 90F day. As long
as I save any significant use of power until the run-up right before
take-off, I can taxi for as long as I have fuel.
John

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