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Message
I think Lynn is correct.
Even a few pounds at the radius of a
normal starter ring gear (as a flywheel) should make a
noticeable
difference.
Hi Cary,
You'd think it would
help, but I had this engine mounted on a Kolb airframe about a year ago, with
one of Tracy's redrives. At the time, I tried adding weight to the flex
plate, and it didn't make any noticeable difference. It should help, but
I'm afraid it will have to be more than a few lbs.
My guess is that the forward and backward tip motion is mostly due to the
positive/negative thrust
as the blades transition from forward motion to
slowed/stopped/reversed by torque reversals. Adjusting the blades to near zero
angle should confirm it.
I think it's clear that this wouldn't
happen if there was no pitch in the blades, so I don't have any plans to try
that experiment. Another thought occurred to me yesterday
though. There may be some tip stall going on, which would complicate
matters a bit. When I first set up the prop, I just picked a number for
pitch. What I picked was 15 degrees, which turns out to be way too
much. On my early revisions of the RV-3 engine, I had a 3 blade 68" Warp
prop, and 15 degrees was one of the higher pitches I ever tried. The
single rotor prop is a 3 blade 72" prop, so even larger. Clearly, 15
degrees is a bad choice, and might explain why I seem to needs so much fuel to
run it :-)
I could swear that I change it from 15
to 10 degrees, but can't find a record of doing that. I also noted that it
took quite a lot of throttle to get 4000 rpm for the video tests, so I'm
thinking I never did change it. Can't wait to try it with a more
reasonable pitch.
Rusty (gotta go fly the Wauchula gyro
now)
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