Enlightening Experience

[Fletcher, Richard]

Here's another good one. I fly IMAC and was getting ready for the Nats. My
plane is a 37% Aeroworks Extra 300L with a killer 150 cc 3W engine. This
plane goes ballistic easily. Early in July I noticed that the power was down
a bit and my friends commented on it also. I was practicing out in PA and it
was hot so I figured it was the density altitude. The power was noticeably
off in Muncie and some of my pattern buddies commented to me that they also
lost power because the elevation is 1100 feet and the humidity was 100
percent. Yet I noticed that other pilots in the Unlimited class were not
having the same problems. So I figured I needed to order a smaller prop and
tuned pipes. Yesterday was the first day I flew since the Nats and the
engine definitely sounded sick. I sat there depressed thinking of what could
be wrong since this engine had been recently rebuilt, it is a killer 150
that I have 300 flights on and that the dealer recently serviced under
warranty with a new case, rear bearing, carb block, gaskets, etc. I couldn't
think of what could be wrong but I remembered having the same problem in
1986 at the Lake Charles LA Pattern Nats wit a piped Rossi .60 engine, it
turned only 12,000 down from 14,600 (remember those days?  :). The problem
was that the Rossi's pipe had a baffle come loose and it restricted the
exhaust. I noticed that the head temps on the 150 were way off, one normal
at 187 and the other very hot at 237. I checked the Pefa canisters and
voila! the one on the hot side had a broken baffle which was restricting the
exhaust. I flew the plane on open headers and what a joy it was with the
power back to where it was during the Spring. The plane was it's usual
ballistic self, straight up at high roll rate, O-O-S rolling. Another tough
lesson learned, PITA.
 
 
 
Rich     
 
 
 

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] On
Behalf Of Don Ramsey
Sent: Monday, August 09, 2004 5:26 PM
To: discussion at nsrca.org
Subject: Enlightening Experience


Some things you hate to admit especially when you are the dumbest link in
the chain.  Hope this might help someone.
 
Thursday I changed transmitters on my plane.  Also, on that day I changed to
a new type of fuel.  During practice, the plane seemed to be a little low on
power but not too bad.  I only did 2 flights.
 
Friday we left for the contest in Lubbock.  Wind that day was quite strong
and I only got one flight on the plane because of a problem.  Power was down
but it was a little hot, the altitude was 3500 feet where I normally fly at
sea level and the strong wind really didn't let me see the power profile.
 
Saturday is gorgeous, cool with only light winds.  On the first round I
realized my power was far off what I needed.  The verticals almost stopped
at the top and I was struggling.  Before the second round I added half
Magnum 1.5 to the new fuel I was trying. Still no power and struggling
thought the tops even with smaller maneuvers.  Third round, change prop
without any help.  Fourth round change props again and add some Mag 2 to the
fuel mix.  Some help but not enough. Sunday, I'm discouraged and still
having power problems.  Fly poorly.
 
Today I'm looking over my plane and thinking about the contest.  For my
backup transmitter I have all the setting recorded that are different from
the other trx.  There is nothing about the throttle there so it must be the
same.  I got the trx and opened the throttle while looking at the engine.
You guessed it, it's only open about 3 quarters. 
 
I'm still trying to learn the obvious.  If you've got a problem, first check
the obvious.
 
Don

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