Stuart & Kathryn Fields wrote:
boB. I believe that the 1/rev vertical is due to tracking, and on my ship,
I either stick track for a ground check or use tip lites. Note us
experimental guys have a blade tip mounted LED two different colors, and we
can use these tip lites in forward flite. One person tracking is possible.



I had forgotten tip lights. On the OH-6 we had cat-eyes but all white
reflectors with a different slash in each reflector (- | and /). I
tried those (2 of them) on an OH58 but didn't have a bright enough
light. I had to do the tracking after dusk.



I also check the vertical vibration by using an accelerometer mounted down
by the passengers pedals.


Even when I do vertical 2/rev, measuring in the same spot, I
don't get any significant readings. However measuring the horizontal 2/rev
just below the swash plate, I can get some significant readings when my fuel
level gets below 1/2 tank and I can feel it in the seat and controls. It
seems that all of the Baby Belles exhibit this phenomena to some extent.
Measurements on the Rotorway Exec showed similar readings but for some
reason their vibrations don't enter the cockpit.
I'm curious as to the sources of 2/rev vibrations. The two mentioned with
Don W I know about and not a lot can be done to either of these two sources,
but are there more sources?


My experience is limited at best with only the aircraft I flew in the
Army. But I'm hoping someday to be back in the air and I'm interested in
what comes from this discussion.

One of the aircraft I had high on my list was the Mini 500. Thanks to
this newsgroup I've lined through that one.


--

boB
copter.six


U.S. Army Aviation (retired)
Central Texas
5NM West of Gray Army/Killeen Regional (KGRK)