LDM

My Feedback: (15)

why is it that I have then all set up perfactly , set them in the neutal position add the specified push rod and control horns and you turn on the radio and they scream as if they are under tremendous load ???
Even on ARfs with the exact pushrods on simple things like rudder set up

redfox435cat

becuasr there is a load o them. if there is any bind at all then the servo is going to have a hard time centering. The servo is acuated by an electric motor oviously and any electric motor only generates power/torque when it turns, so it can have a hard time finding a single spot. this is usually noticable on new models when everything is really tight. You do need to eleviate any binds in any way shape or form. and more ARF's even though they'er better that they were a few years ago more offten than not, are set up wrong. I'll usually get a minor buzz on one or more servo for the first 2 flights then it's gone since things losen up. I've found the biggest culprit are new CA hindges being really stiff.

Also, what kinda of servos are you using and what kinda of power sourse are you using. Some of the digital servos don't like a 6V battery.

JohnW

My Feedback: (6)

"Because there is load on them." - yup, that pretty much sums it up. Other sources of load/resistance would be linkage drag, friction in the actual linkage connections (like pin in hole), and the weight of the surface can also load the servo. It is not really possible to totally eliminate all of this, but as mentioned in the previous post, it is important to eliminate any surface or linkage binding.

LDM

My Feedback: (15)

Thanks guys , I did not even think of the hole in the linkage . I know the CA hindges are tight so that can be part of it , I will try to hand work the hindges , open the holes and see what I can do .
Thanks
LDM

exeter_acres

My Feedback: (2)

what kind of servos????

if they are digital...it is normal....

if they are analog....see above

MinnFlyer

My Feedback: (4)

I was going to ask about digitals too.

Something else... If they are NOT digitals, try wiggling the control surfaces to see if the noise stops. If it does, the engine vibrations will do the same thing, so it's nothing to worry about

LDM

My Feedback: (15)

They are standard HiTec hs425 BB

bhole74

Another possible cause according to Hi-tec, servo case screws too tight. If it doesn't go away after the first few flight (as mentioned above) try loosening the screws in the bottom of the servo case 1/4 turn.

From the troubleshooting section on Hitec's web site:
Q. Servo hums under load
A. This can be normal, the servo is trying to hold position against the force of a load. If it hums when no load is applied, try loosening the servo case screws a quarter turn.

Ed_Moorman

My Feedback: (1)

Analogs should be pretty quiet. Hitech digitals scream like they were being tortured. If your buddies have never heard them before, they'll swear your radio is going to self destruct.

JohnW

My Feedback: (6)

LDM... Don't open the holes. That can induce flutter and trim issues. I just mentioned it as one source of why servo's chatter. OK, if they are really tight, you can very slightly enlarge the hole, but you don't want any slop whatsoever. In general, I'd think you'd never need to enlarge the holes.

There are ways to reduce the linkage friction at the connections. Best way I know of is ball bearing linkages, but they are expensive and the diff isn't significant enough for typical sport use to justify the cost. FYI... I have several planes with ball bearing linkages. Very friction free setup... When I turn off the radio, all surfaces instantly droop. I still have servo chatter. The surfaces move so freely that the weight of the surface and even air movement in the room do to central air is enough to get the servos to bark almost nonstop. This is normal.

Cheers

LDM

My Feedback: (15)

Thanks guys great info and an education for me as usual