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Old Aug 20, 2005, 11:01 PM
plane obsessed
Cody WIlson's Avatar
Denver, CO.
Joined Nov 2003
3,872 Posts
Wierd servo problem-

Flew the beejebus out of my Bat tonight- had a great time, and flew for at least three hours! It was awesome!

But then I came in a *little* too close and caught a tip on a bush- the plane flipped this way and that a couple times in the air and came in for a fairly 'soft' landing in another bush. I picked it up and the right elevon was about 1/2" down... it still worked, but NOT centered... It is an HS325HB with Karbonite gears. The gears arent stripped. I didn't shut off the TX or change anything- and my sub-trim isn't enough to get it straight again. Could the gears have slipped- or the POT move somehow?

This is wierd. I have NEVER seen anything like this happen before. I don't really want to hack into it and dig it out, because I want to fly it next weekend at the Super77 at Williams peak- and will buy a new servo if I have to. Not enough time to get it back from Hitec... Maybe I could just re-position the servo arm on the splines- but it makes me a bit nervous using something that for some reason just... moved.

Thanks, Cody
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Old Aug 20, 2005, 11:08 PM
gas tires and oil
prplgoat's Avatar
malad, idaho
Joined Dec 2004
2,438 Posts
you probably split the plastic arm so it slipped a couple splines. you'll have to get it out to replace the arm."just a guess from experience!"
marty
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Old Aug 20, 2005, 11:42 PM
slope-a-holic
aneigher24's Avatar
Oak Park, CA
Joined Mar 2005
577 Posts
how do you have the pushrods... you may have bent one in a wierd way if they are on the bottom if not, do as the goat says check all of youre horns/cleveses to make sure...

Good luck
@lex
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Old Aug 21, 2005, 12:53 AM
plane obsessed
Cody WIlson's Avatar
Denver, CO.
Joined Nov 2003
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Z-bends and metal clevises all on top and secure. I'll check the servo arms-- they are heavy duty and don't look broken. The servo's are fairly low-torque, and the servo arms are made for big 3-D gassers (and hopefully stand up to mid-air hits )

I guess I'll just try moving the arm on the splines and hope for the best!
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Old Aug 21, 2005, 06:28 AM
gas tires and oil
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malad, idaho
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if the arm's ok,run it thru its full movement with your fingers on it with some resistance.you'll feel it if you've broke a gear tooth!
marty
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Old Aug 21, 2005, 09:35 AM
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I think purplegoat is right. I've had that happen once and it really had me scratching my head.
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Old Aug 21, 2005, 11:45 AM
Feeling FrSky
surfimp's Avatar
United States, CA, Santa Barbara
Joined Feb 2003
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I've had similar things happen. Never checked the plastic arm, guess it could be that. It's like the servos recentered themselves, really aggravating. I've only had it happen with Hitec stuff

Steve
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Old Aug 21, 2005, 12:17 PM
plane obsessed
Cody WIlson's Avatar
Denver, CO.
Joined Nov 2003
3,872 Posts
Quote:
Originally Posted by prplgoat
if the arm's ok,run it thru its full movement with your fingers on it with some resistance.you'll feel it if you've broke a gear tooth!
marty
Nope, feel's buttery smooth!

So, Impster- do you still use the same servo's?
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Old Aug 21, 2005, 12:20 PM
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On mine I slammed into a paved road while flying combat. I didnt have any time to mess with it so I just adjusted my subtrim waaay over to correct it.
The down side is the output shaft seems to loose some sharpness of its splines and its going to happen again.
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Old Aug 21, 2005, 12:55 PM
plane obsessed
Cody WIlson's Avatar
Denver, CO.
Joined Nov 2003
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What kind of servo's you running? I'm assuming they are Hitec's, but are they STD Karbonite types? I love the servo's- they center well (except for now) and have almost *zero* slope in the drivetrain.
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Old Aug 21, 2005, 01:32 PM
plane obsessed
Cody WIlson's Avatar
Denver, CO.
Joined Nov 2003
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OK, so I hacked into the wing and dug out the offending servo. As it happens the DuBro HD servo arms did not mesh properly with the servo's output shaft. The entire servo arm was swiveling on the servo I must have grabbed the wrong servo arms when I was building it. DOH!

So I'm gonna hack open the other side, dig that servo out and install the STOCK arms. God I hope this doesn't happen on my Funtana

Oh, well, it wasn't going to be beautiful forever. Thanks for the input.

Cody
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Old Aug 21, 2005, 01:52 PM
Feeling FrSky
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United States, CA, Santa Barbara
Joined Feb 2003
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Quote:
Originally Posted by Cody WIlson
Nope, feel's buttery smooth!

So, Impster- do you still use the same servo's?
Yep. Never really been sure of what caused it, but never thought to check the output arm. Could very well be that. It's been weird, I've had them seem to "recenter" from one flight to the next. Radical trim position changes are no bueno!

Steve
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Old Aug 21, 2005, 01:56 PM
That Freeking Laird Guy
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United States, CA, Riverside
Joined Feb 2002
9,083 Posts
You gotta be carefull with Hitec servos since lots of servo arms "sorta" fit. It's easy to grab the wrong arm and pop it on. I've done it myself and shoved a Futaba arm onto Hitec servos. They work fine until you give em a decent whack and then they slip a few splines.

TFLG
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Old Aug 21, 2005, 09:19 PM
Crikey never leave beer behind
steve wenban's Avatar
Mt Annan Sydney Australia
Joined Dec 2003
23,175 Posts
Yep had that happen to me thought Id stripped a servo but it was the arm slipping on the servo output spline all splines are not created equal ! . You would think that if they can pick a standard for plugs they could at least use a universal output shart spline.
SteveW
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Old Aug 21, 2005, 09:22 PM
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Have you seen the new aluminum output arms that have a clamp built into the back to prevent stuff like this? Pretty cool.

Mine was simply a case of crashing too hard. 50 feet straight down onto pavement will do that sort of stuff.
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