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 Post subject: Xeon heli - unstable in altitude
 Post Posted: Wed May 05, 2010 10:01 pm 
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Joined: Mon Dec 28, 2009 3:39 am
Posts: 10
Help,
I built a GURU Xeon heli (300 size) and used my HoneyBee CP3 head and Esky 7.5 gram digital servos. I installed a GURU brushless motor (GE38H) 3900kV with Exceed-RC Proton 18A ESC and 11.1v 1000mAh lipo battery. The tail gyro is Hobby King (HK401) gyro and my radio set is Futaba 7CAP.
Now here is the problem – the altitude changes abruptly in an otherwise stable hover. I tried a different ESC (30A Suppromodel.com) and same behavior. I tried decreasing the normal pitch range and that helped a little. I am not sure if the pitch (-4 to +8) is changing or the head speed is changing spontaneously but the result is abrupt rise or drop of 1-3 feet. I have built several other helicopters an they are very stable.
Any ideas – try another motor, try another receiver or what?
Thanks,
Vince


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 Post subject: Re: Xeon heli - unstable in altitude
 Post Posted: Thu May 06, 2010 1:02 am 
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Joined: Tue Jun 02, 2009 6:08 pm
Posts: 6
Hello there,

Any headspeed detail measured?
The pitch slider may got a chance to "stuck" due to a high headspeed. (2500rpm?) :idea:

Regards,
Mystic

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 Post subject: Re: Xeon heli - unstable in altitude
 Post Posted: Thu May 06, 2010 2:21 am 
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Joined: Mon Dec 28, 2009 3:39 am
Posts: 10
Mystic,
I do not have a heli tach so cannot report head speed. The pitch slider seems to slide smoothly and evenly. I have slowed down the normal throttle in my computer radio and that seems to help some but not normal yet..
Thanks,
Vince


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 Post subject: Re: Xeon heli - unstable in altitude
 Post Posted: Thu May 06, 2010 12:22 pm 
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Joined: Tue Jun 02, 2009 6:08 pm
Posts: 6
Vince,

Yes, you can feel the pitch slider slide smoothly at static. However, once it is flying, there are torque applying on the pitch slider (depends on the paddle weight and length of the flybar), it causes sticky if you have a high headspeed (the torque is proportion to the rotating speed).

This situation is quite trouble.
If your heli. is a bit heavy, it always need a stronger trust which need higher headspeed + larger pitch, but it results a sticky behavior.

Mystic

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-Fly me to the moon-


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 Post subject: Re: Xeon heli - unstable in altitude
 Post Posted: Fri May 07, 2010 3:59 am 
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Joined: Mon Dec 28, 2009 3:39 am
Posts: 10
I have discovered the problem of my unstable heli. One of the ball links in the head was disconnected from the ball and riding on the shaft of the main blade clamp as noted in the attached photo. I pays to inspect the head ball links carefully.
Vince


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