Servo Gremlin Caught on Film - RC Groups
Thread Tools
Feb 09, 2003, 09:22 PM
Registered User
Deltawing's Avatar

Servo Gremlin Caught on Film

So there I sat today, re-glueing the broken fuse on my GWS P-51 for the 3rd time and re-running the mental video of my 3 attempts to fly my little birdy.


It would leave my hand-toss and soar nicely straight out about 50 to 60 feet while rising up to about 17 feet and the MOMENT I would apply just a breath of aileron, she would act like she didn't hear me, start to wobble, forcing me to react and then she would seem to do the opposite of what I wanted and then.. BAM, she'd hit the deck - and yes, I had my tx set correctly and tested just before flight.

The initial climb out behaviour told me I had the CG right and I have all my throws at recommended or less so I've been really consternated (that's the polite term :-) at why I haven't been able to get my Stealthy Stang to stay in the air.

So there I am hauling out the CA and the 5-minute again and I wire up a battery to re-adjust the throws on the ailerons when I hear this weird clicking in the servo. Not every time I power up - it's intermittent (the ugliest word in the english language) and servo begins to alternate between working fine and working really strangely - halting at about 30% of it's throw for no appearant reason.

After taking it apart, the reason became readily appearant. See attached pic. The servo is a GWS Naro std.

I then recall when I was first building this bird and was lashing up the rods for the ailerons and the servo was a little off so I TWISTED it a little. I remember hearing a little zzzzzt sound but since it seemed to work properly, I thought nothing of it.

I think a LOT of it now.

This is only my second plane so I'm still on the shadowy side of the learning curve this seems like a really important lesson - to NOT finger-tweek the servos!!

The nasty part of this was that it worked SOMEtimes - enough to fool me into looking everywhere else for the problem and going nuts in the process.

Now, I may still not ba able to fly this puppy but at least now I know I've eliminated one very serious impediment.

Last edited by Deltawing; Feb 09, 2003 at 09:52 PM.
Sign up now
to remove ads between posts
Feb 09, 2003, 09:32 PM
Registered User
Jaffa's Avatar
That would explain it!!

P.S. Just finished my P-51 too and don't have the guts to go fly it!
Feb 09, 2003, 09:48 PM
Registered User
senor_paco's Avatar
Those ittle gws servos can't put up with tweaking like the full size servos can. I found that out too, but before I flew. At least from balsapr or aeromicro you can get the gear sets for a couple of bucks, better than buying a new servo. just be careful.
Feb 09, 2003, 10:44 PM
Registered User
Deltawing's Avatar
Originally posted by Jaffa
That would explain it!!

P.S. Just finished my P-51 too and don't have the guts to go fly it!
You don't need guts - just glue :-)

I do know what you mean though. I was nervous about mine too - but I just looked at my battle-scarred GWS Beaver and realized, heck, their just foamies. They are built to be repaired and ya can't learn to fly em by just lookin' at em.

To me, it's all about progress. As long as I know more today than I did yesterday, I figure I'm on top of my own game.

I stopped crashing my Beaver after the first 3 flights and have since logged over 5 accident free hours on her. I'm convinced I'll get my Mustang up there, too. She just needs another 1/2 ounce or so of 5-minute epox repairs and she'll be doin' 4-point rolls all by herself :-)

Life is short, launch the son of a gun.

Feb 09, 2003, 11:45 PM
Oops, reversed elevator!
Caveman's Avatar
There are some of the encouraging words.
I'm still hesitant to fly my GWS P-51. Last week, I broke the left wing in half and today I broke the right wing in half.
I spent so much time building and spray painting the airplane. Maybe it's best left it on the shelf.
I'll go back and fly my slowstick.

Feb 12, 2003, 02:26 AM
Registered User
Deltawing's Avatar
Well I fixed the gremlin in the servo, now I just need to polish off the brain gremlin that tells me I can fly just fine in a strong breeze :-)

I will say that I actually FLEW the Stang today. Smooth rollout, nice gentle turn and made it all around the field perimeter but as I came about into the wind on a final leg, the wind banked her steeply and she fell into a dive I couldn't recover from.

Still, it's progress. I did feel in control for the full minute or so I was in the air. Enough in control that I'm convinced that if I can just wait for a calm day, I will actually keep her up for a full charge.

It was thrilling! She moves WAY quicker than my Beaver, that's for darn sure.

I do have to say, though, that these GWS Stangs are fragile sons of guns. Even a GLANCE at the ground and the fuse just blows apart.


Thread Tools