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04-17-2004, 02:37 AM
Hi Chuck Beaty, welcome to Scots forum.
I hope that you enjoyed a little respite from the demands on your experience and knowledge.Even if you don't know which way rotors should be twisted!!!!
Chuck, I have come across the situation that as the gyro airspeed is increased, without increasing the engine rpm, the gyro rolls to the left, and also rolls to the right as the airspeed is decreased.
Can you please shed some light on this for me?
04-17-2004, 06:43 AM
I assume, Paul, you've convinced yourself tlhe cabin's not lopsided and the two halves of the tailplane are set to the same angle of incidence.
That being the case, the only thing left is teeter bolt friction.
As airspeed is increased, the amount of teetering increases and teeter bearing friction tends to lay the stick over to the left.
Metal-on-metal teeter bearings should be avoided. Teeter bearings should be either needle roller or Garlock DU type Teflon-Kevlar lined bushings. There should also be a tad of end play to avoid binding.
If that doesn't work, it's back to the ouija board.
04-18-2004, 04:03 AM
Chuck, it looks like back to the ouija board then!!!!
I have needle roller bearings and about 5 thou end play, and there is basically no rotor shake even with the "magic" bush replaced with an alloy one. I offset the hole in the alloy bush to give me some more nose up with the hang test. The Rafs usually fly around the 3 degrees nose down and the cabin has too much windscreen frontal area to the relative wind. With the keel flying at 1 degree nose up the Raf cabin does not nose down so easily with an increase in airspeed.
Another reason for using an alloy bush is that it is easier to compare rotors, regarding shake, without the "magic" bush.
I will have to take some accurate measurements and try to get to the bottom of this "roll" situation.
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