Regularly breaking servo gears

[mhn]

Hello everybody,

This is my first post here on HeliFreaks and wanted to thank you all for your very helpful posts all along.

I have an Ion-X Actro32/3 H - MAH 700Dt G2 blades, and have ran into the same problem twice during its 4 first flights:

The heli enters into some kind of resonance on SPOOL DOWN and ends up breaking the teeth of the 3 x JR 8301 servos controlling the swashplate.

It also pops off a link on the blade holder mixers.

This is very annoying, as you might imagine, and I am hoping that someone has a solution for this.

FWIW my blades are quite tight in their grips (you must shake the heli while on its side to make them droop). Certainly as tight as I run them on all my other nitro machines, incl. the Extreme.

Otherwise the machine flies beautifully well (still running-in the Lipos though).

Any help or suggestion is welcome.

Thanks,

Michel-Henri

[misskimo]

hey , in normal mode I put about 0 degrees pitch in the blades on spool down , when you have alot of neg , most helis do this for some odd reason

Tony

[BobbySmith]

I would try what tony suggest i run -1 in normal mode!!


Bobby

[Dr.Ben]

Ground oscillation issues as you noted can sometimes be caused by a screwy chordwise center of gravity in your mainblades, or least ones that are not matched. Try another set of blades and see if the problem persists. If it goes away, find someone who has a Koll balancer and match the ones on your set of blades.

Another way you can rule out any kind of a lead lag issue is to carefully "feather" each blade in its respective grip, then lock it down there. Go through your spool down again and see if it stops.

***Blades tight in their grips is not the same as blades feathered in their grips and then locked down there.

Ben Minor

[fitenfyr]

Wow...
That must be some kind of resonance.

I run about 4 or 5 negative on mine with 9252's and even on the camera mount it spools down nicely without any issues.

I will even hit hold and "stick" it to the ground if it is a bit windy. That is set for -10.

Have you checked your ball links? Are they tight? that might be causing the gears to wear and become weak.

Has me kind of nervous though as we have 8311's in our Gasser.

[Russ McC]

I think Ben is on the right track. I have noticed this moor with the Ion then my other MA helis but it has never been bad enough to damage the heli. Landing on a hard surface also aggravates this, grass is moor forgiving.

[misskimo]

0 degrees pitch will fix it all , most of the blades made now days are matched sets unless you go with the cheap kind, my cuz has 2 Ions , both has the same blades , and one does the chicken dance and the other one dont , dialed it down on colective like I have always done on all 20 of my electric helis Ive had , and fixed the problem, the worse ones Ive had was the eco 8 , logo 10 , genmantel heaven, logo 30 did it a few times, rappy E, hawk E and the voyager E ,

Tony

[misskimo]

also , the rubber dampers wore out will cause this , the rappy was the worse on that one , my fury E at neg 10 doesnt do it , never done it , I do think the 3rd bearing and the beafyness of the carbon frames is the reason why it dont.
also , make sure the CG are right , paddles are level and running true , and the blade grips are = in tightness too . but I very doughtly its caused by the blades not =
electrics flex because they are made very lite , except for the Ion , it dont flex but very little

Tony

[mhn]

Miskimo, will try to be careful staying around 0 Deg after landing. I just remembered, both times the oscillation happened after an autorotation landing (-10/+10), but then again, I always land in autorot :wink: could have been after a sliding one though.

Ben, I will check the blades on the Koll. But I thought that blades of the MAH caliber should be already balanced... Note: I bored the blades from 4 to 5mm. Done it very carefully on a big drill-press. But who knows, there might be some error in there. Will do it on the lathe next time around by removing the collets.

Based on your suggestions, my take on it is that the stop after the forward sliding motion of the autorot might be upsetting the looser blade of the two first, which throws the whole system out of balance, with not enough RPM to rebalance it.

Russ, very valid assumption here: I do fly and land over hard ground (asphalt).
Nothing I can do about that however. :(

Will fly it today with feathered and locked blades, avoiding sliding autorotations and maintaining 0 deg after landing and during spooldown. :arggg:

Did we miss any thing else?

Thanks,

Michel-Henri

[misskimo]

also make sure the clips on the spindle are on , if one slips off will cause this Im thinking ,

Tony

[mhn]

Misskimo, I will be installing some skid stops too, in order to avoid the ground resonance effect on asphalt (No more running autos possible after that)

[misskimo]

you should be able to do autos , flip the throttle hold with around -4 , land and feather off the blades somewhere around 0degrees

Tony

[Russ McC]

O yes I used to do running (sliding) autos all the time with my SEs and Fury’s but my Ions did not like this at all even using the same blades (SAB & Rotor Tecks) I run my blades fairly tight. I did not pull my hair out trying to solve this I just stopped doing what it did not like.

[Heli_jack]

is the surface you are landing on hard or grass? Watch out for the hard surface.

[mhn]

I know what you mean Russ. Same here. Never had this problem with any of my other X-Cells or Robbes before. Same decision as yours about the Ion-X from now on.

Too bad, cause I fly over asphalt and running autos can be a lot of fun.
Anyway flew it today, with tighter grips and rubber skid stops.
Seems fine but didn't try any sort of unorthodox auto.

Will keep you guys posted.
Thanks for the help,

Michel-Henri

[Tabbytabb]

Yep, had this problem also with a stock Ion, and one with an FAI head.

I just decided that the Ion likes to dance :)

I found that the thing I did to aggravate the situation is I like to play around after autoing by hopping the machine up etc and this for sure gets the Ion dancing.

Now if I have to land on asphalt I go immediately to 0 pitch and let it spool down on its own.

I am not sure why the Ion in particular does this, my Jokers dont and I have never seen the extreme do it.

Tabb

[JonMann]

Had the same problem, took a shim out of the head, went away (this was recommended by Chris). Apprently the ION doesn't like the head shimmed up tight.

[misskimo]

yeh , that would explain it , huh? thanks my head on the fury is kinda loose , kinda

Tony

[mhn]

Interesting point !
John, do you fly and land on hard surfaces? Has the prob disappeared?

My head is not "tight" but rather "hard" :arggg: :D
in the sense that I mixed one hard (90 duro) with a regular one.
Will keep those for the time being because I like the head's reactivity as is. Will see if the blade tightening and rubbers on the skids are enough to alleviate the prob.

Michel-Henri

[mhn]

BTW, just a quick thought: I have mounted the servos directly onto the sideframes i.e. without the brass eyelets.
Do you think that using those would help dampen the shocks transmittted to the servos during oscillation (by allowing them to rock slighltly) and thus spare the servo gears ?

[Russ McC]

BTW, just a quick thought: I have mounted the servos directly onto the sideframes i.e. without the brass eyelets.
Do you think that using those would help dampen the shocks transmittted to the servos during oscillation (by allowing them to rock slighltly) and thus spare the servo gears ?

Michel

These models are very smooth but there is still some vibes and yes they might help in your situation also. I have had too many servos fail from vibration not to use the grommets. Thanks to the Ion I’ve had no moor bad servos but I still like all the help I can get.

[JonMann]

mhn,

I take off and land from asphalt. removing one of the shims completely eliminated the "dance". prior to doing that, if I auto'd down and when low HS rpm, would dance and shake violently like you discribed, although I never lost a servo from it.

I have two ION's, one of them did this one of them didn't. the one that didn't only had one of the thick shims in it, that one that did had a thick and a thin shim in the head (have no idea why I built them differently :? ) removing the one thin shim did solve the problem.

I mounted my servos with brass eyelets and grommets, heard it wasn't really necessary, but why take a chance??

-jon

[misskimo]

hey , well I just went through my first gear set like yours , on its first attemp to hover , never made it to a flying headspeed , went into a wobble or shimmy at about 600 to 800 rpms on start up , killed throttle and she did a dance from hell , broke 2 9252 gearsets and 1 9251 gyro gear set , boom strike which didnt hurt nothing because it was to slow , almost tiped over it was so bad , Chris told me to that the MAH blades are tail heavy which makes for a quicker cyclic responce but very touchy at low RPMs , I have a new set of TGs thats going on there that the CGs are more stable

Tony

[mhn]

Misskimo,

I read about your mishap in the other thread. Sorry about that.
From what little experience I have with the Ion I would suggest :
- first tightening your blade grips a bit more (and follow Dr.Ben's suggestion around top of the thread)
- initiating rotor motion by handswinging it before switching into soft start.
- In case you are using the Hacker 77-O - Heli, mine has a bizarre 'hickup' a few seconds into the spool up, which tends to offset the blades if not tight enough in their grips, and if taking off on slippery grounds. Does anyone else have the same behaviour on their ESC?

Hope this helps,

Michel-Henri

[rappyripper]

Mine is also a little tricky. I have a hard time too to get it started without folding the blades around the main mast. The start is quite jerky and if the blades are too loose, they might hit the boom. Happened twice now before I tightened the blades more. Too tight and it starts to wobble in a hover. Once it is spinning all is well and about two seconds into the spool-up, it jerks a little and then accelerates to where it needs to be. After that no problem. I do not have the dancing like lile misskimo, I run 710 sab's or 690 V's.

JB