I have a Futaba S3010 high torque digital servo hooked up to the elevator of my Jet Legend Goshawk. I just hooked it up to the receiver for the first time and it is fluttering up and down about 1/16th inch very rapidly (dissapates over a few seconds) and "vibrates" as it moves up and down when the elevator stick is moved on the Tx. It is also buzzing. Any suggestions on the most likely cause? If I reach inside the fuse and push forward on the servo arm lightly it goes away. I have not balanced the stab but was told it is not necessary.

If you really have an S3010 servo, it is an analog, medium torque. Not digital or especially high torque. You sure about the number?

J. Swanson

[&:] You are abo****ely right, grabbed the wrong box to get the number off of. It is a S9351. It has 192 oz-in torque. Also, I removed the elevators and the buzzing and fluttering stopped. When I put them back on the buzzing comes back, but the "fluttering" has settled down. When I lift up slightly on the back of the stabs the buzzing goes away so I am assuming it is coming from the stabs being out of balance???

The servo is under a slight load holding the stab in the neutral position...hence the very annoying buzz. When you take the load off the servo with your finger, the buzzing stops...

ive the same problem on 9351s mounted on 30% yak.....all servos buzz but the rudder goes into violent shudder back/forth that you can stop by grabing control surface....rep said it seemed to be the extreme deadband/resoulution.......and these servos are expensive....never saw this with digital/top of the line hitecs/jrs

Used to have a simlar prob under florscent lighting. But that was years ago Analog servos FM equipment.....

Did the rep tell you if it would damage the servo over time and if it was usable in that condition or did he suggest returning the servo for service?

what he said was my pull/pull tension was incorrect.....so ive tried adjusting tension....l/r...slax/no slax...i use my fingers to duplicate full/scale tensionmeter....so far no luck...than I installed nelson 1 1/2 in bellcrank....so that pull/pull wires did not exit directly off servo.....balllinks-to prolinks-to bellcrank(double ballbearing)...pull/pull cables exit off bellcrank....it still didnt help.....the advice I got was when airload was on flt surface ...they will settle down...........what do you think....cause these are the most expensive servos....very pretty....ive bought......the rudder when I first power/up oscillate about 500 cycles a min...kelly

Mine fluttered like crazy this first time too. Now it is settling down a little, but it still moves slightly up and down around neutral. It looks weird [:-]. I was wondering if it would settle out once the plane had flight loads on it, but what a risk to take with a new airplane. I agree, these are expensive servos and they should not be fluttering like that. Anyone else have this problem with a Futaba S9351???

Is your "period" key sticky?

Dave

Hey rc guy....why bother with that inane comment.....next you will be complaining about spelling....I hope you really dont obsess about stuff like this.....remember we are just a bunch of modelers typing out our experiences....so rc guy talk to your counselor...work it out/get a life...etc signed............................................ .................................................. .................................................. kpc

...ive....just ....opened the box of my JL t45 and I have to say (getting off subject a little) all looks great all formers etc are very very well glued the seams are no were near as tidy as my other comp arf/bvm/cermark kits but who cares its less than half the price of the rest EVERYTHING else ie the retracts oleos etc are first class very pleased.

I always use JR servos they buzz but don't move like that so ?? I wouldn't risk using that

Ant

The Futaba 9351 is known for the flutter or bounce that you have mentioned - especially when using large surfaces.

Futaba got over this problem by making a new servo - 9155.

It has the same speed and torque as the 9351, but the amplifier has been modifed to stop the flutter problem.

modtron
Oxford UK

You can try shortening the length of your servo arm. I don't know if this is practical on your model. Digital servos will always give out a slight buzz when turned on but you need to get rid of the "bounce" I have seen it on some F16's and the only way we could get rid of it was changing the servo arm length. Futaba, JR and Hitec/Multiplex did the same.

Hi Pantherman,

Here’s what I would do:

Temporally tape 2oz to the leading edge of each elevator half.

At rest and when the elevator stick is moved:
If the buzzing has stopped (mostly) and the oscillations have completely stopped then don’t be concerned. Remove temporary weights and go fly.
If the buzzing has stopped (mostly) but the oscillations are still there then I would choose an alternative servo.

HTH
Eric

Thanks everyone for the replies. Eric, I will try that and see what the result is.

Again, thanks all!

Just as a follow-up on this. I took the elevator mechanism back out of the Hawk and replaced both clevises included in the kit with ball links. The only play at all before was the small amount of play where the clevis pin went through the hole in the stab mechanism control arm. That allowed for about 1/16th play in the leading and trailing edge of the elevator when installed. The ball links took all the play out and it is not held rigid. When I put it back in and powered up the servo, SHAZAM....the flutter was gone. I guess just that minute amount of play is enough to cause the 9351 to "hunt" for center and flutter. I asked Barry to look at the plane before I put the ball links in and he said that the small amount of play that was present in the elevator was not enough to cause in flight problems, or to be a concern, but I guess these servos are ultra sensitive to ANY play at all. Hope this helps someone else in the future who is dealing with these same servos!

Woody