Air crash investigators needed.

I ditched my 48” Extra yesterday, and I’m trying to piece together what I did wrong and also what’s salvageable from the wreckage. The motor and speed controller are fine, as are the wings and the fuselage from the wing tube back, it’s just a little bit of damage to the front end. :pinch:

I tested the tail plane servos whilst they were still within the airframe and noticed that when I moved the elevator the rudder twitched. I’ve now taken all the servos out and I’m trying to get to the bottom of the problem.

Details:
Elevator Servo: Hitec HS-5085MG
Rudder and Aileron servos: Hitec HS-5065MG
Receiver: Spektrum AR6210 (DSMX)

Issue:
When moving the Elevator servo the Rudder servo occasionally twitches.

Replacing the Rudder servo with an Aileron servo (i.e. identical servo) = No twitches, this would suggest a dodgy servo.

Putting the Rudder servo back in and exchanging the Elevator servo (HS-5085MG) with an Aileron servo (HS-5065MG), = No twitch, so maybe it’s not the servo.

Finally go back to the original twitchy configuration but try a different receiver, an AR7610, and the rudder servo doesn’t twitch!

If it was the servo, the same issue should be replicated using a different receiver but it’s not…

…exchanging the rudder servo with an identical servo in the original receiver does rectify the problem suggesting it is the servo…

…I’m confused, so far it seems to require a unique combination of one particular HS-5065MG servo together with an HS-5085MG servo in a AR6210, change anyone of these components and the twitch isn’t there.

Anyway here's a video to show what's happening:



Any ideas? Further tests?

Hi Chris
When you swapped the aileron rudder servos did you move all the other controls to test for jitter?

Also what battery did you use and what voltage was it giving?

Try the tests with all servos connected.

Hi Ron,

I did connect all servos to check for jitter but kept it simple with just the two in the video. The receiver is running off of the ESC BEC and giving out 6v (Measured).

Repeat the test with the radio about 2 (or more) metres from the rx. You might be experiencing swamping at this range.

BTW, if you have collected all the little pieces of ply you should be able to jigsaw the front end back together again. It'll take a while, but is a lot quicker than making new parts and scarf joints.

Hi Mike,

:blush: I think you might have pin pointed the issue, I think I must have been swamping the RX :blush:

The odd thing is that it would twitch without fail, now I can only get it to twitch occasionally, if at all! Even with the TX next to the RX.

As to the bit's, I've got most, if not all of it. I plan to park it for a while and revisit it on a wet Sunday.