GP750 Drifting.
12-18-2011, 12:39 AM
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GP750 Drifting.
Hi all
I have a GP750 gyro with a DS650 rudder servo. I have a previous post where my DS620 rudder servo burned out on me after 5 minutes of flying ... I replaced the servo with a DS650 and added an Align voltage regulator between the gyro and servo to bring the volts to the servo down to 5.1V
I am trying to set the gyro up but no matter what I do the tail drifts to the left very slowly in heading hold mode ... My subtrims/trims are zero, I have tried setting the tail blades at an off set in order to keep it from drifting in normal mode but that makes no difference. And no matter where I put the gain, the tail will drift, if the gain is too high the tail will wag and still drift. If I decrease the gain the wagging stops bit the drifting increases. Even tried playing with different head speeds but to no avail. The distance from centre of the servo horn to the ball link is 10mm as per the manual. The second hole on the servo arm.
The only thing I can still try is to move the gyro somewhere else, but that would mean moving it further way from the main shaft (I have a Titan X50B)
I also have the gyro on two gyro foam pads with the metal plate in between. Could that be the problem perhaps. I can imagine a gyro on two foam pads will have more "play" and might vibrate more.
Any one have any advice on what else I can try?
Marcel
I have a GP750 gyro with a DS650 rudder servo. I have a previous post where my DS620 rudder servo burned out on me after 5 minutes of flying ... I replaced the servo with a DS650 and added an Align voltage regulator between the gyro and servo to bring the volts to the servo down to 5.1V
I am trying to set the gyro up but no matter what I do the tail drifts to the left very slowly in heading hold mode ... My subtrims/trims are zero, I have tried setting the tail blades at an off set in order to keep it from drifting in normal mode but that makes no difference. And no matter where I put the gain, the tail will drift, if the gain is too high the tail will wag and still drift. If I decrease the gain the wagging stops bit the drifting increases. Even tried playing with different head speeds but to no avail. The distance from centre of the servo horn to the ball link is 10mm as per the manual. The second hole on the servo arm.
The only thing I can still try is to move the gyro somewhere else, but that would mean moving it further way from the main shaft (I have a Titan X50B)
I also have the gyro on two gyro foam pads with the metal plate in between. Could that be the problem perhaps. I can imagine a gyro on two foam pads will have more "play" and might vibrate more.
Any one have any advice on what else I can try?
Marcel
12-21-2011, 02:44 PM
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RE: GP750 Drifting.
Wow. every piece of advice I would have gave you have already listed. Going to keep an eye on this post so I may learn somthing new as well. If you find your fix please post it.......Barbie 
12-28-2011, 02:11 AM
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RE: GP750 Drifting.
Hi all
Another weekend of testing and fiddling ...
Almost getting there, tried moving the gyro to a different spot, turned it 90 degrees and tried different mounting pads, no luck.
Then tried my GY520 that I know works that I have in another heli and it somewhat stopped the drifting.
Seems to be ok for a while, flipped to idle up, flew around, went back to normal mode and the drift came back ...
Pulling my hair out here. it come and goes.
So, seeing that it comes and goes the way it does, all I can think of is that the engine seems to be vibrating more than it should, possibly due to the fact that it is a new engine with only about 8 tanks of fuel through it.
I have set the top end needle to where it runs quite well, but a tad on the rich side for now, have not set the low end needle yet. Will try that and see if I do not get a more consistant mid range, might even try a different glow plug. (I am using te R3 that came with the engine)
Will keep you posted.
Another weekend of testing and fiddling ...
Almost getting there, tried moving the gyro to a different spot, turned it 90 degrees and tried different mounting pads, no luck.
Then tried my GY520 that I know works that I have in another heli and it somewhat stopped the drifting.
Seems to be ok for a while, flipped to idle up, flew around, went back to normal mode and the drift came back ...
Pulling my hair out here. it come and goes.
So, seeing that it comes and goes the way it does, all I can think of is that the engine seems to be vibrating more than it should, possibly due to the fact that it is a new engine with only about 8 tanks of fuel through it.
I have set the top end needle to where it runs quite well, but a tad on the rich side for now, have not set the low end needle yet. Will try that and see if I do not get a more consistant mid range, might even try a different glow plug. (I am using te R3 that came with the engine)
Will keep you posted.
