jst4fun

My Feedback: (4)

Here is the set up in a funtana 90.. Jr8103, R700 rx, 5 ds811's and 1 537 on throttle.
I turn the switch on to the rx and the the servo's twitch like crazy I have full control over them and if I hold them all they will calm down and stop. But as soon as one starts they all start like a chain reaction from the slight movement of the plane. It's like they are almost bouncing on there center???? I had all of these in a 1/4 scale cub and had no problems what so ever. I am using a small 700 mah battery but even on a full charge they do it right from the get go. I don't have a clue as what to do I could use all the advice I can get. I don't dare to fly the plane like this, even though I have full control of every surface. This is the first problem I have ever had with anything JR, I hope its simple, and is an easy fix.

scottm

I have the exact same problem with 811's in my Funtana 40 and EF Edge, too. My rudder starts oscillating so bad I'm afraid it will break something. It is worse with a 5 cell nimh, but it does it with a 4 cell too. I am probably going to run an analog servo on the rudder, but what is the deal with these servos? Can the damping or hysteresis or something be adjusted?

dsnyder

The 811 because it is a single ball bearing servo has a bit of play on the top gear. This play of the top gear combined with the servos aggressive centering abiltity has the tendency to overshoot the mark just a bit, and a slight oscillation occurs. If you can stop the jittering with light pressure there isn't anything wrong with the set up or the equipment, and it will not happen in the air due to flight loads. It would only happen on the ground. If however it takes more pressure, or does not stop with pressure, there may be a problem with the pot of the servo, or there is excessive slop, possibly in the gear train.