Cleared the ground for a brief period today. As far as the airplane is
concerned,
everything is good. CG seems to be right on the spot. Much better as it
was 12 years
ago at the first flight with the SOOB.
Here is the reason why it was not a flight. A few days ago when I started
high speed
taxi, as soon as it picked up air speed, the engine started to sputter and
almost cut
out totally. This was at the same RPM as at a run up, where it does not do
that.
With a wiggly tail dragger as the Avid is, there was no way reading enough
instrument
for making a preliminary analysis. I recorded the instrument panel with a
GoPro at
2sec intervals.
Looking at the first pictures, the answer came up right away, increasing
pressure
under the cowl where the intake for the engine is located. Like the EGT
shot up over
1600 just before the sputtering started. Since my radiator air is going to
the
outside of the cowling, there was no impact on cooling. Btw cooling is
really good.
At an OAT of 95F, oil and water stayed at around 170F no matter what I
did.
For todays runs, I taped the inlet around the prop hub shut. Sure enough,
the
sputtering occurred at higher airspeed, and was not as total, however, EGT
was still
going to around 1600.
The conclusion is, I have to open the cowling exits a lot.
Richard Sohn
N2071U
http://www.fairpoint.net/~res12/home.html
Congratulations Richard.
Do you have a ram air scoop or cold air box on it?
No pictures came with the message.
I would put a water manometer tap under the cowl to check the intake
pressure for
sure. That carb should not be affected by small changes in ambient air
pressure
unless the vent to the float bowl is plugged. Is there a fuel pressure
regulator in
the system? Tie the tail up in takeoff position and run it up. I assume
the tanks are
in the wings.
1600 EGT is normal at high power. How far is the EGT probe from the port?
I'll be down that way about Oct 1st.
Paul Lamar
Very exciting Richard, keep us posted.
John
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