No flying this week as the weather is terrible again. The wind is about 30MPH, but that’s probably a good thing as I replaced all four servos in my RS352 this week and there are still a few teething problems. Normally replacing servos is just a case of unscrewing them and putting in the new ones, but it’s a lot messier when all four are held in foam with hot melt glue.
The reason for replacing the servos was the stuck right aileron which I experienced last week. It turns out that the elevator was also faulty, but in a really weird way. All the original servos are ES08MA servos with metal gears. The elevator servo had an issue whereby it was causing all the servos to flutter during power on and also as the elevator was operated. I had thought this was just the start up cycle of the radio, which is a Futaba FAAST set using an old Field Force 8 with FAAST module and R617FS receiver. It must be some kind of electrical fault causing either noise or excess current, but operation of the elevator would cause spurious glitches on the other channels. I’m now anxious to fly the aircraft with the new servos to see how much this was happening during flight. My feeling is that coming out of a loop and releasing the elevator to neutral would have caused an aileron and rudder glitch.
Anyway, two days after placing an order with RobotBirds, four brand new servos and a pin vice arrived on my doorstep. All four servos have now been replaced with the new Hitec HS65MG servos, which operate so much better than the cheap ES08MA servos that didn’t seem to centre very well and were much slower. The only problem is that I’ve now got another weird issue with the ailerons. When I flick the switch to bring the ailerons down as flaps, occasionally one or both servos will appear to jam and not find the position, fluttering wildly as if it has stalled or the control surface is stuck. The problem is that with the servos stuck in with hot melt glue I can’t easily remove them again to check what is wrong. Initially I thought it might be due to a low voltage on the 4.8v Rx NICAD I was using for safety reasons, rather than plugging the LiPo into the ESC and having the motor system live when I was setting up. I took the propeller off and used the bigger LiPo with the same effect, so it isn’t lack of voltage. However, I suspect that it’s to do with the new servos being slightly bigger than the old ones with the servo arm very slightly higher up. I’m going to try cutting some of the material out from around the servo head and see if that is what is causing the problem. Otherwise I’m going to have to extract the wing servos again for further inspection. They definitely worked before they were installed though.