Steve,
Thank you for conducting this test. The attachment contains
the data my Advanced Flight Systems engine monitor captured. It logs in five
second intervals. A lot can happen in five seconds when the pilot is throwing
switches and opening and closing the throttle. The data shows I did not
re-enable the primary injector switch until after landing. So no rpm or fuel flow
data was captured during most of the glide. Oil pressure indicates the
prop was driving the engine. I don’t remember if I bypassed part of the
super charger flow or not. The manifold pressure before the event was only 36”
MP so I was not a full power. The rpm dropped from 6700 to 2500. Manifold
pressure started dropping but I’m sure I was pumping the throttle and may
have pulled the super charger bypass. What I don’t understand is the last
seven lines of data. MP is between 18 and 29.4 at idle. This is while I was
trying to taxi but could not move the plane.
Your data supports a sharp drop in rpm. Is the MAP plot
EC2 fuel map or manifold pressure? If manifold pressure your test also
indicates a high manifold pressure with a low rpm condition.
Bobby
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Steven W. Boese
Sent: Saturday, March 26, 2011
9:31 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Exhaust
obstruction test
Bobby,
A plot of data collected from my engine
stand with a butterfly valve to restrict the exhaust flow is attached.
The MAP was taken only to about 16”
rather than full throttle before starting to close the valve. I tried to
close the valve gradually and opened it rapidly. The valve didn’t
seal perfectly since I couldn’t kill the engine completely, but it was
still pretty effective. The EGT’s didn’t drop until the valve
was almost as closed as I could get it and at no time did they rise until the
valve was opened. About 22 psi of exhaust gas pressure was developed with the
valve closed.
The engine did not run smoothly with the
valve closed but there was no popping. Remember that this is with a 13B
with the peripheral exhaust which may behave somewhat differently than a
Renesis.
Steve