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Dynon Pitch Servo Question
- Thread starter rv7plt
- Start date
Brantel, you appear to be knowledgable on the Dynon AP. We have a Skyview in our RV-10 and the AP feature is out of the box, (ie not calibrated other then torque, we are at 100 %, or tuned (whatever the proper term is)). As you can tell we are not AP savy. We are just at 50 hrs and will be begining our AP tuning when winter breaks. This post got me thinking about our AP and I have a question, as fuel burn takes place the AP will show "AP slip" and the stick will jerk. We disconnect the AP and adjust the aileron trim and are good to go for a little while (1/2 hr perhaps) and the scenario will play out again. Is this normal or does fine tuning fix this?
Thanks Ron
PS, Don't mean to hyjack this thread. Brantel is you can move this reply to another thread please do so.
Thanks Ron
PS, Don't mean to hyjack this thread. Brantel is you can move this reply to another thread please do so.
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rvmills
Well Known Member
Couple data points for John (OP) and Ron.
John, I have my roll servo settings set for a 25 degree angle of bank, and the pitch servo is solid as a rock during turns. Like Brian, I've been in some pretty good bumps and have had good performance (and no inadvertent disconnects). FW update 5.4 made the pitch servo very solid!
Ron, my first indication of aileron out of trim is a slight rhythmic bump in the ailrerons (actually the airplane just does very, very slight wing dips as the AP tries to hold it wings-level). I do like you...disconnect the roll servo, re-trim, and re-engage the roll servo. I don't see an AP slip indication though. I have SV-32's in a heavy -6, classic Dynon...not Skyview. Brian's question about your servo is a good one, given you are at 100% torque, and I'd also ask if you see any slight bumping/thumping before the AP slips.
Brian will hook both you guys up with good info!
Cheers,
Bob
John, I have my roll servo settings set for a 25 degree angle of bank, and the pitch servo is solid as a rock during turns. Like Brian, I've been in some pretty good bumps and have had good performance (and no inadvertent disconnects). FW update 5.4 made the pitch servo very solid!
Ron, my first indication of aileron out of trim is a slight rhythmic bump in the ailrerons (actually the airplane just does very, very slight wing dips as the AP tries to hold it wings-level). I do like you...disconnect the roll servo, re-trim, and re-engage the roll servo. I don't see an AP slip indication though. I have SV-32's in a heavy -6, classic Dynon...not Skyview. Brian's question about your servo is a good one, given you are at 100% torque, and I'd also ask if you see any slight bumping/thumping before the AP slips.
Brian will hook both you guys up with good info!
Cheers,
Bob
Sorry for the slow responce. I check new post two times a day usually and missed your responce.
Brantel, I do believe we have the SV-42 . I'll check tomorrow. We installed the unit that Dynon recommended last year. I see today they recommend the SV-42 and I do believe it hasn't changed.
Bob, the stick shakes as you describe and the ac begins to turn. It's at this point that a slip indication is given on top of the screen. We have not flown since the last update was installed into the SV.
Hoping to get a few more hrs.in if winter will let up, before we head for Sun n Fun. Would be nice to get the ap working properly before such a long trip.
Thanks Ron
Brantel, I do believe we have the SV-42 . I'll check tomorrow. We installed the unit that Dynon recommended last year. I see today they recommend the SV-42 and I do believe it hasn't changed.
Bob, the stick shakes as you describe and the ac begins to turn. It's at this point that a slip indication is given on top of the screen. We have not flown since the last update was installed into the SV.
Hoping to get a few more hrs.in if winter will let up, before we head for Sun n Fun. Would be nice to get the ap working properly before such a long trip.
Thanks Ron
Brantel
Well Known Member
Is your elevator servo slipping? (Slipping indicator lights and you feel a jerk in pitch)? If not, I would leave the elevator servo alone and just tune it following the directions in the latest manuals...
Keep in mind that contrary to your last post, the outer hole on the servo arm reduces the force the servo can apply to the pushrod. The further away from the shaft you get, the more the force available is reduced.
Now for the roll servo that you stated above you are having problems with slipping even at 100% torque with the SV42 servo and you think it is installed with the pushrod in the outer most hole.
The only thing you can do is move to the middle hole and give that a try. This will increase the force available from 36lbs to 44lbs which is a ton when it comes to an RV. I can't imaging that any RV would require much more aileron control force to counteract fuel burn unless something is rigged wrong or binding.
WARNING: MAKE DOUBLE TRIPLE SURE THAT IF YOU MOVE THIS PUSHROD TO THE MIDDLE HOLE THAT YOU CHECK THE COMPLETE RANGE OF MOVEMENT TO ENSURE THAT THE SERVO CANNOT GO OVERCENTER AND JAM!!!! ENSURE THAT YOUR AILERON CONTROL LIMIT STOPS ARE IN GOOD ORDER!!!
The above change will increase the amount of force the servo can produce and should stop the slipping. It will also reduce the travel available to the servo but 99.9% of the time this is not an issue with an RV since we move our controls so little for alot of response...You should also tune the roll servo as directed in the latest install manuals. Doing so will reduce the jerkiness of the AP and help prevent slipping. Nice smooth control inputs is what you should be seeing from the AP....
Keep in mind that contrary to your last post, the outer hole on the servo arm reduces the force the servo can apply to the pushrod. The further away from the shaft you get, the more the force available is reduced.
Now for the roll servo that you stated above you are having problems with slipping even at 100% torque with the SV42 servo and you think it is installed with the pushrod in the outer most hole.
The only thing you can do is move to the middle hole and give that a try. This will increase the force available from 36lbs to 44lbs which is a ton when it comes to an RV. I can't imaging that any RV would require much more aileron control force to counteract fuel burn unless something is rigged wrong or binding.
WARNING: MAKE DOUBLE TRIPLE SURE THAT IF YOU MOVE THIS PUSHROD TO THE MIDDLE HOLE THAT YOU CHECK THE COMPLETE RANGE OF MOVEMENT TO ENSURE THAT THE SERVO CANNOT GO OVERCENTER AND JAM!!!! ENSURE THAT YOUR AILERON CONTROL LIMIT STOPS ARE IN GOOD ORDER!!!
The above change will increase the amount of force the servo can produce and should stop the slipping. It will also reduce the travel available to the servo but 99.9% of the time this is not an issue with an RV since we move our controls so little for alot of response...You should also tune the roll servo as directed in the latest install manuals. Doing so will reduce the jerkiness of the AP and help prevent slipping. Nice smooth control inputs is what you should be seeing from the AP....
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Thanks Brantel. You are correct in that the outermost hole reduces torque just a brain ***. I knew better. I do not believe the pitch servo is giving us any problems. It's the roll. I will check which hole the roll servo is in later today. I fully understand the over centering issue if we chose to move to a shorter arm hole.
As for the jerk in the stick, it's only when the servo slips that this happens. If we comand a 180 the responce is very smooth. Our control via stick, are very smooth through full deflection on the ground and smooth through all deflection we have thus far experienced, ie. we have never made full deflections in flight.
I feel we have been maticulas (spelling) during the structural process, but lack in the avionics department. It's kind of difficult installing an autopilot and being the test pilot for said AP without having flown an AP to know what one is capable of doing. We will learn and get this working as I realize we are just getting started.
Thanks Again
Ron
As for the jerk in the stick, it's only when the servo slips that this happens. If we comand a 180 the responce is very smooth. Our control via stick, are very smooth through full deflection on the ground and smooth through all deflection we have thus far experienced, ie. we have never made full deflections in flight.
I feel we have been maticulas (spelling) during the structural process, but lack in the avionics department. It's kind of difficult installing an autopilot and being the test pilot for said AP without having flown an AP to know what one is capable of doing. We will learn and get this working as I realize we are just getting started.
Thanks Again
Ron
Brantel
I think you found our problem. We purchased the roll servo when we were building our wings at least two years ago. Back then they were recommending the SV-32 which is what we have. We are in the outermost hole (A) as recommended. I rechecked Dynon's site and they now recommend an SV-42. It's obvious we were not the first ones to have the slip problem. Dynon would not recommend a larger servo requiring more stick force to overcome the servo resistance while manually flying for no reason.
I'll have to contact Dynon and see what they have to say.
Thanks Ron
I think you found our problem. We purchased the roll servo when we were building our wings at least two years ago. Back then they were recommending the SV-32 which is what we have. We are in the outermost hole (A) as recommended. I rechecked Dynon's site and they now recommend an SV-42. It's obvious we were not the first ones to have the slip problem. Dynon would not recommend a larger servo requiring more stick force to overcome the servo resistance while manually flying for no reason.
I'll have to contact Dynon and see what they have to say.
Thanks Ron
