Marcus763

Hi,

I'm just setting up my Edge ready for it's first flight. I have 2 Futaba 9351 Digital servos on the rudder, linked into a Futaba MSA-10 and when I turn on the radio the rudder vibrates/flutters about 1/4" at the trailing edge non-stop, or until I move the stick or stop it with a light press from my finger. Then if I move the stick again or just brush the trailing edge of the rudder with my finger, the flutter starts again....any ideas ?

I am using the same servos on the elevators and again through an MSA-10 (Futaba's version of the JR Matchbox) but the elevators are fine and don't do this.

I'm using a single switch and one 6v 3300mah battery pack.

Any help/cure most welcome!

Thanks...

MMcConville

My Feedback: (4)

In general digital servos can do that at times. Notmally if it stops when you touh the rudder then it wil also damp out with airflow and not do it in the air. I cant speak any more than in general terms though as I have no experience with the Futaba gear.

Marcus763

I did wonder if the airflow would stop this, I'll check it out with the engine running as soon as I get a chance.

How safe do you think it is to fly like this ?

MMcConville

My Feedback: (4)

With JR servos when they act that way, I'd say its 100% safe. I cant speak for other brands

rc_boy_12

My Feedback: (2)

My 2 cents, if your batteries are freshly charged, and are 6-volt, alot of servos will jitter because of the volts coming form the battery, because the battery has a full charge. it could very possibly be that

Marcus763

The problem is nothing to do with the voltage or fully charged batteries. From what I know so far, it's more to do with the signal racing up and down the extension cords and getting out of sync.

I tried placing the Edge on it's side, so see it the weight of the rudder on the linkages would stop the vibration, and it certainly helped. Also when I lightly shake the tail of the plane, the vibration stops. The elevators don't do this at all, even though they are the same servos and linked up in exactly the same way as the rudder, through a Futaba MSA-10.

I feel happier about flying the model now.

rmh

Marcus- the problem is -as Mike noted -not a biggie - but here is what causes it :
The servo -even very good ones, have a tiny amount of internal play
The rudder , has a lot of moment arm (length ,fromt ot back BUT because it is hinged vertically - the force to move it at rest is very small.
When you start the system --the servos try to center up - in doing so - they create a tiny movment (left or right) in the rudder .
This instant movement, "winds up " the gear lash , comprsses them minutely and the rudder moves as much as possible (till it is suddenly stopped ).
So ---it is like compressing a spring -- it wants to spring back --and does .
this repeats it'self.
over and over as the long moment -light weight makes for a perfect spring.