The most likely culprit remains a blocked
exhaust. Thanks again for taking the time to setup and conduct the test. If you
need someone to test your injector delay circuits with higher MP and an
electric prop I’ll volunteer. Of course if they help resolve tuning
issues you may never get them back.
Bobby
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Steven W. Boese
Sent: Sunday, March 27, 2011 11:59
AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Exhaust
obstruction test
Bobby,
The MAP in the plot is manifold pressure
in inches of Hg. The throttle setting was not changed while the exhaust
valve was closing or closed. The increase in manifold pressure results
from the decreased air requirement when the rpm decreases due to the choked off
exhaust. A decrease in air volume drawn out of the intake plenum
along with an unchanged throttle body opening gives a manifold pressure
rise.
This is consistent with what you
experienced.
I’ve attached a couple of photos of
the test setup.
One other observation that I forgot to
mention is that with the valve even partly closed, the noise level decreased
remarkably.
Steve
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Bobby J. Hughes
Sent: Sunday, March 27, 2011 12:33
PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Exhaust
obstruction test
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