Wouldn't that put too much heat on the spar? A melted spar would be

really

bad news!

It is easy to insulate the spar but real hard to insulate the prop :-)

Al Gietzen wrote:

Many pushers have the exhaust going through the prop near the hub with no
ill effects on the prop, except for some discoloration caused by the exhaust
gases.  If the exhaust hits the blade a foot or so from the center of the
hub, that part of the blade is in the cool air more than 10 times as long as
it is in the exhaust gas stream.

I guess I'll find out if it's OK.  That's how mine is set up.

Al

Most of those pushers are direct drive Al. In that case it is possible to 
index the prop so the exhaust pulses miss the blades. Can't be done
when the gear ratio is other than an integer number. Every so often the
pulse hits the blade. With Tom Jordans EZ you could hear this happen.

Paul Lamar
 
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