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› HBKII - front to back wobble?
05-14-2008 03:28 AM  9 years agoPost 1
MickyGilly

rrApprentice

Perrysburg, OH - USA

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Hi all. Thanks - as always - for your help!

I've finally got a patchwork HBKII up in the air, flying pretty well. Chased down most of the vibration I could find, but sometimes it wobbles a bit and I'm not sure why.

Is this normal, maybe depending on the air currents? It seems to be more of a front to back wobble (tail goes up and down) than a side to side or left to right wobble.

There is also some minor fraying on my belt (it used to slip off, but I think I fixed that) and I suppose that could be the problem.

But I'm not terribly excited about having to change the belt, so am wondering if this happens to sound familiar to anyone.

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05-14-2008 03:51 AM  9 years agoPost 2
zaw

rrKey Veteran

Lebanon, NH - USA

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Check your fathering shaft. I posted that question here last week and turn out that my fathering shaft was not tight and it was shaking the tail like you described.

ಠ_ಠ HBK2 built with inexpensive parts! ٩๏̯͡๏)۶ Gaui425

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05-14-2008 06:02 AM  9 years agoPost 3
BOB WHO?

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Downey, Ca.

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Make sure that the belt is tight and lubricated (silicone spray)

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05-14-2008 02:29 PM  9 years agoPost 4
fenderstrat

rrProfessor

Aston,Pa

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usually bobing up and down(tail)can be traced to a few things but the common ones are low headspeed and soft dampers...if it goes away in idle up its headspeed

Compass helis Support Team
PerformancePlusRC field rep
Mini Titan/SE
TEAM KBDD

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05-14-2008 02:48 PM  9 years agoPost 5
MickyGilly

rrApprentice

Perrysburg, OH - USA

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Thanks zaw, bobwho, and fenderstrat.

I've checked the spindle a few times, and have tightened the outer nuts on it as tight as I can while allowing the blad grips to swivel freely. I had previously squirted some triflow all along the belt.

Which is not to say it still can't be those items

I'm using a 9t pinion with a 4100 motor (like the brushless for the blade cp). This would put me at a lower headspeed than a 10t on a 3800.

Oh! I have substantially more positive than negative pitch (due to mechanical, not radio, setup I think). So maybe I'm using too much pitch relative to headspeed? Which might also explain why it seems somewhat - but not totally - sensitive to ground effects and wind?

I'll check this out again tonight when I'm back in my heli room

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05-14-2008 04:42 PM  9 years agoPost 6
MickyGilly

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Perrysburg, OH - USA

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Oh, and the motor and esc were running pretty hot. Seems that might also support the low headspeed / too much pitch idea. Wish I could check it now! Will post back later...

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05-15-2008 01:47 AM  9 years agoPost 7
MickyGilly

rrApprentice

Perrysburg, OH - USA

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fixed!

Just to report back - changing the pitch of the blades (less positive) helped the wobble. I also took the TG off, but I can't see how that would have been the cause.

Thanks fender!

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05-15-2008 02:09 AM  9 years agoPost 8
MMike

rrElite Veteran

Holland,Mi-USA

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Just to clarify, Less pitch = More headspeed @ hover.

Tail bobbing is a common symptom of low headspeed.

The fixed pitch Roto Fly bobs like crazy in the Heli-Max demo video.

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05-15-2008 02:11 AM  9 years agoPost 9
MMike

rrElite Veteran

Holland,Mi-USA

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I've heard training gear can "amplify" vibration.

I suppose it could do the same with tail bobbing.

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05-15-2008 02:19 AM  9 years agoPost 10
MMike

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Holland,Mi-USA

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Sorry to be Captain Obvious.

I just read what Fender already said.

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05-15-2008 02:25 AM  9 years agoPost 11
MickyGilly

rrApprentice

Perrysburg, OH - USA

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No prob MMike - thanks a TON for all your help getting this thing flying... on and off the boards. No way I could have gotten it together w/o your help.

This thing flies great now!!

Way way way better than a bcpp. Man, after learning on that thing, this feels HUGE! The bcpp was good training

I'd post flying pics, but it got dark out here. Maybe later.

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05-15-2008 02:28 AM  9 years agoPost 12
MMike

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Holland,Mi-USA

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05-15-2008 02:31 AM  9 years agoPost 13
tryan02

rrProfessor

Canton, Missouri

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I like some up and down wobble but side to side aint to bad either.

No Really I am the club President!!!

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