i have the great planes 1/3rd scale matt chapman cap. this is my first big plane and i am having a problem. i am running futaba 9351's in the ailerons and elevators and everytime i turn on the plane the elevators start fluttering and i don't mean the servo's chattering , i mean major elevator flutter. mainly just on one side but they both do it. any way thought it might be a bad servo. replaced but it didn't help then tried the servo extension that didn't help either tried using ferrite rings, that didn't help. tried moving the antenna and even tried running the extension outside the fuse but to no avail. then as i was removing the entire right horzontal stab and elevator from the two aluminum tubes it quit fluttering as soon as the stab cleared the first tube. has anyone else seen or heard of this and what could be the fix? i really don't know what else to do. i even tried another futaba digital servo, (a 92520) and it still did it just not near as bad. any help would be greatly appreciated. thanks darryl

what kind of batts you running?

alot of times if you run 6v, servos will jitter, because on a full charge you are slightly over 6v.


Just a thought

i am running 6volt fromeco's but like i said this is way more than jittering. they are fluttering so bad that the elevators are moving more than an inch back and forth

Are you using PCM or PPM? Does it do it when the engine runnig or not? Dennis

Does Fromeco make 6 volt batteries? I thought they were 7.4 Lion batteries. If they are 7.4, (which I'm sure they are), this could be your problem If you're not using a regulator.
Carroll

Are your servo car servos? Make sure the Futaba servos aren't car servos. They will Jitter like crazy, they can't handle the high voltage.

You're right, Fromeco doesn't make a 6V battery pack. All 7.4 volts un-regulated. I hope he's using a regulator or those servos could be fried.

How close is your transmitter when this is happening? Was your antenna up or down? Have you tried lowering your antenna and walking away from the plane? Sometimes the transmitter can overload the receiver in an effect called "swamping".

thanks guys for the ideas, yes they are 7.4 volt packs and yes i am using regulators. also the servo's are car servos but whem i told frank noll (mister futaba) which servos i was going to use he said there wouldn't be any problem. also i haven't even started the engine yet this is all happeneing with the engine off. also this is happeneing with the transmitter in very close proximity of the airplane but with the antenna down. also the same servos are in the ailerons without any flutter would the srvos be better at say 5.8 volts? any more ideas? thanks. darryl

This is really weird, but I'm assembling the same plane for a friend and his servos were doing the exact same thing. They were JR 8411 servos but they had a lot of gear slop which was causing the problem. Replaced them with Hitec 5945 servos and problem solved. So, you might look into gear slop or possibly too small gauge wire extensions to the servos (just a hunch). Are the Futaba servos digital?
Carroll

The 9351's and many others, even the 8611's will do this, only with no load placed on the control surface. These servos are very quick, and with the large control surfaces and the momentum build up during movement, they tend to over centre and try to compensate, even after switch on, hence the so called flutter. Once there is load put on the surface, this 'problem' will go away. I have a Comp-ARF Yak 2.6 with 9351's all round. One stab flutters with no load and engine off. This even happens on a 8611 in a Comp-arf 2x Extra. One aileron will flutter like anything, but no problems in flight. If you place a little bit of load on the surface, such as just put your finger on it, the flutter will stop, and the servo won't try to fight back into a flutter etc. So I don't think there is anything to worry about. Just an inherited issue with quick servos and large control surfaces...

What you have is a servo with a too tight deadband. When loaded with a certian load this flutter results. The only fix is to repace the servos with another type or static balance the control surface.
Yes the problem will go away when the servo is loaded but when you have the problem you have excessive gear wear and battery drain. It needs to be fixed.