----- Original Message -----
Sent: Wednesday, February 16, 2005 6:26
PM
Subject: [FlyRotary] I found the
power
Today I finished installing the firesleeve on
the remaing fuel lines, made some stand-offs so that the fuel lines would
not be right up against the engine, and finished hooking up and securing a
few other items. With the top cowling off, I ran the pumps for a
minute, then checked for leaks...none found. Then I started the engine
and ran it for 20 or so seconds and shut it down and reinspected for fuel
leaks. None found. I restarted and taxiied away from the hangar a bit
so as to not be as loud for others in and near the hangar and did a full
power runup. I hit 5600 static rpm's. In the past, the best I could
hope for was 5200, most of the time settling for 5100 rpm's. I taxiied
back in and installed the top cowling....max rpm's 5100. Took the top
cowling back off....max rpm's 5600. One more try....5100 with the
cowling back on. It is beginning to become more clear to me, that one
of two things are affecting rpm's. Option one is that with the top
cowling on the engine is ingesting heated air and just cannot develop the
same power as when it ingests outside unheated air. Option two is the
muffler bearing may be worn. I'm kinda leaning toward option
one.
I was thinking of
installing two small NACA ducts on the bottom of my cowling with two hoses
coming up to feed air to my TWM throttlebody. The NACA ducts I
purchased from Van's RV (made for cowling ventilation) already have a male
outlet already molded in the assembly, so you just slide a hose over it and
secure with a clamp. Very simple installation.(Works well for my cabin
ventillation) If I recall correctly, they are about the same size as my
throttle body bore. I wonder if I will loose much efficiency as the air goes
through the corregated hose, and if the Van's RV ventillation NACA ducts
will provide a sufficient volume of air. Of course while flying, I would
have the advantage of a little bit of ram effect as well as the ability to
suck in fresh outside air that has not been heated inside the cowling during
taxi/takeoff run. Any opinions/suggestions would of course be much
appreciated. I will discuss the vapor lock issue in the next post, so
as to not complicate responses, etc. Thanks to all who reply.
Paul Conner
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