Stripped both Futaba 9402s in flight

[ConRadical]

Ok guys.. My yak 33% Aviation Models yak went in today, again!

Here's what i believe happened.. Both right wing servos stripped(9402s) and overloaded the regulator. Engine died, i had no control and it went in all on it's own and it ONLY BENT THE LANDING GEAR!!! Ok, I got realy lucky but does any know if these 9402s have plastic gears somewhere in them? I was under the impression all the gears were either brass or steel. If someone doesn't respond soon i'll have them apart by tomorrow and find out for myself.

Thanks guys!

[Bunky F. Knuckle]

Conrad, there has to be a "fail point" in any servo. Yes, there is a plastic gear in the 9402. It is teh PRIMARY gear. You'll have to disassemble the entire gear train to get to it.

Sorry about what happened man!!! SUX!!!!

Chris~

[ConRadical]

Well well, i hate that the PRIMARY gear is plastic when the specs on it say they are metal(brass or steel)

I'll just send them off to futaba and let them do is since they are under warranty. I wasn't really happy with these in my wings anyways. Good reason to upgrade to the digitals and put these in a glow plane.

The Yak will fly again by the end of the week

Thanks Chris!

CG

[Bunky F. Knuckle]

No sweat, Chet!!!

Hate to tell ya that as well. All of my JR servos are MG/Alloy gears. But they also have a nylon gear as the primary. Discouraging, somewhat. But knowing that I won't have to buy a FULL gear set is reassuring to me if I strip a gear!!

[adrian]

wow - how do you guys still fly normal servos(non digi) in big planes - with all the knowledge available - gaint scale needs big serious servos - proper power distribution and serious batteries - fact - we seem to spend on the planes and then use make do stuff for the rest and when some thing fails cry to the manufacturer or bad mouth suppliers - ugly but true

use the best products in your gaint - a must!!!!!!!!

[youngflyer]

adrian, while it is becoming a neccesity to use high quality stuff, you could still use a single rec, non-digital servos, and regular nimh with a fm 8ch rec! that plane would still fly the same and you would barely notice the difference as long as your not using weak analog servos!

[Bunky F. Knuckle]

Those 9402's have over 130oz in. if I recall correctly????? PLENTY for a 33%!!!!

Hell, I used JR 2721's in my first GS'er!!! 32% Extra!!! Digital wasn't out 6 years ago when I bought this stuff!!! So, needless to say, I couldn't use digital!! The first digi's come out several months afterwards!

[ConRadical]

yeah.. they are plent. 2 per wing. I let a friend talk me into putting those in telling to forget the matchbox and digital and do this. I have digi's everywhere but the wings, i'm going to change them over.

[ConRadical]

I'm sitting here rebuilding these servos right now and i just found another stripped servo, 1 out of 4 servos left in the wings!!!

[adrian]

i hear you - but i have learnt the hard way - so now i realy only use the best possible - lost many planes trying to go el cheapo and got my arse kicked - so i try to get real!! day one sell the crap and get better - sorry!!

[ConRadical]

	Quote: Originally Posted by adrian
	i hear you - but i have learnt the hard way - so now i realy only use the best possible - lost many planes trying to go el cheapo and got my arse kicked - so i try to get real!! day one sell the crap and get better - sorry!!

Actually, these servos aren't that cheap, about $75 each.

[GremlinX]

The rediculous thing I heard is that even metal geared servos still have a plastic pinion...

[rc4flying]

Actually there is nothing wrong with the servo selection, it is in the setup. The suggestion of forgoing the MatchBoxs is where you may have went wrong. IMO. I have never found many servos match in their extreme throws. You may think they throw the same, exact measurement tell different, and over time, it does not take much fight between the two servos on one surface to wear down and fail. Yes, if you have a case of servos to choose from, you can find servos that match in throws and leave out the match boxes, but I use 9402 in all my 40% planes up to now with out a single issue. But I use a Match box like devices. If the servos are constantly fighting each other, any servo is going to fail in a big bird. Time takes their toll on that little nylon gear, that I think all metal servo geared servos have from my experiences. I think they are necessay to isolate noise from the motor and the gear train. Just what I was told.
I am now fighting a setup problem on a new plane, and it is coming down to a problem with the control horn bolts being in a the slightest difference in angles and that will and does change the throw rates off between the 2 servos on that surface, which in turn would work on the servos. I have no problems on the other control surface and the angle of the control horns match.
Without knowing more and seeing it for myself, Incorrect setups and not using and device for matching servo throws, to save money, can be the problem here. Trying to save money, can usually cost you more in the end. Just my opinion.

[ConRadical]

Joe, my servos are pretty closely matched throughout the whole curve. I switched servos and arms around to make them match. I'm not sure what happened or if my extremely heavy 3D flying has anything to do with it.

[rc4flying]

ConRadical,
Please don't take this wrong, but matched and pretty closely matched are two different things. I have setup mine and my nephew's planes and it pays to get the setup right. I do 3D enough myself, but my nephew hammered his planes in 3D and I do mean he could get down right merciless on his snaps and downline blenders, and his planes are all 9402's on everything. He had never had any problems before giving up flying last year. He did many demos and even finished well at the XFC. The servos were in his plane for 3 yrs to that point when he quit flying. No problems. Again, IMO, not using something to match the servos and check their power draw when there are more then one servo per surface can and usually does cause the kind of problems you have experience. Glad to hear that there was not much damage. To me, 33% size planes are at that point that you have to change the mind set on plane setup and not use the smaller plane and glow fuel planes kind of thinking.
Just another quick thought, but if the surface are flexing any maybe this would contribute and even was there a possibility of flutter that you may have missed hearing ?
Just my 2 cents.