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Message
Your video has really inspired me. One of the keys to problem solving is it
to convert your impressions to numbers. You've just invented the "Duffy prop
analysis method".
Measure the distance from you hangar door to your prop. Put mark on
pavement, say at 20 ft. Put another mark at 30 ft. That's where your camera
goes. Now, video your engine as well as others at those same locations.
Calibrate your system by measuring the distance between the pleats on your
hangar door.
Now go home, sit on the couch, get a beer. Fire up your videos. Find the
worst deflection by using slow motion. Measure how far prop tip is from the
hangar door pleat in background. So it's going to be around 1/4" on your video
screen. We can convert that mathematically to actual tip deflection at prop!
You've now measured deflection of 4 different aircraft and haven't lost a
finger.
Then you just test your various ideas, trying to beat the best measurements
you could find.
You could also use the video to measure prop diameter. Just in case one of
the planes has different diameter. That would also prove how accurate this
method is. I expect it would be unexpectedly accurate and meaningful.
Write up your test. This would be great one for Contact.
What a great video. I ran it in slow motion.
Hi
Al,
I never
thought about running this in slow motion, but
holy crap!!!
For the
dialup folks, here are a couple frames from the video, when the engine was
probably around 2500 rpm. These are sequential frames, so only a 30th of
a second apart. Take a look at the blade flex, but then note
the position of the engine from rotational torque. It's undeniable
that this is a torque reversal
issue.
Before I
change dampers, I may make another video at more controlled rpms, and with the
camera zoomed in on the engine/prop more.
Rusty
(creating a monster)
-al wick
Cozy IV powered by Turbo Subaru
3.0R with variable valve lift and cam timing.
Artificial intelligence in
cockpit, N9032U 240+ hours from Portland, Oregon
Glass panel design, Subaru
install, Prop construct, Risk assessment
info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
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