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Old Mar 13, 2007, 04:08 PM
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Video
Pusher Prop Wash Compensation

Behaviour of a pusher gyro without and with prop wash compensation.

Jochen
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Old Jun 21, 2013, 05:27 AM
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Prop wash test
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Old Jun 22, 2013, 12:40 AM
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Is this an issue with wash over the tail?
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Old Jun 22, 2013, 01:21 AM
Lou
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Hmmm ... well my interest is piqued. After looking at the vid several times I am missing what you did to correct 'prop wash' .... but then I am about half drunk.

Nice looking model though.
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Old Jun 22, 2013, 02:56 AM
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Quote:
Originally Posted by Obake View Post
fter looking at the vid several times I am missing what you did to correct 'prop wash' ....
The rotation is caused by the spiral slip stream corkscrewing off the prop and hitting the vertical stabiliser at an angle causing it to generate 'sideways lift'..

Two ways you can fix it either offset the vertical stab or add thrust offset, thrust offset is best because it varies with motor power, so it doesn't upset low power/glide trim as offsetting the vertical stab would do.

If it were be I'd have offset the motor thrust line so that (looking from the rear) the motor was angled to the right slightly (right thrust). Looks like the OP decided to move the entire motor over to the right, this is another way of doing it which should work just as well, but it looks a bit odd.
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Old Jun 22, 2013, 06:20 AM
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A little left rudder would stop it too. If it's for a gyrocopter it will need a lot of rudder at any rate.

Gord
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Old Jun 22, 2013, 07:45 AM
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Only problem with using rudder (exact same thing as offsetting the vertical stab) is that it will only be 'right' at one power setting. One option with computer Tx's is to program in a throttle to rudder mix, that would work well.
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Old Jun 22, 2013, 08:34 AM
Canadian Bacon
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Yeah, I don't see a moveable rudder on it. Maybe weight shifting like a hanglider. Used to fly those things. You move the bar and wait for something to happen. It was great fun just the same. Lucky I didn't kill myself.

Gord.
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Old Jun 22, 2013, 08:49 AM
Lou
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Quote:
Originally Posted by JetPlaneFlyer View Post
The rotation is caused by the spiral slip stream corkscrewing off the prop and hitting the vertical stabiliser at an angle causing it to generate 'sideways lift'..

Two ways you can fix it either offset the vertical stab or add thrust offset, thrust offset is best because it varies with motor power, so it doesn't upset low power/glide trim as offsetting the vertical stab would do.

If it were be I'd have offset the motor thrust line so that (looking from the rear) the motor was angled to the right slightly (right thrust). Looks like the OP decided to move the entire motor over to the right, this is another way of doing it which should work just as well, but it looks a bit odd.
Ahhh .. thank you. I see now. I looked again at the vid and I do see where he offset the motor. I was 'seeing' the back of the black mount as a shadow.
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