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Real Raptors . Mikado Modellhubschrauber . GrandRC

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e-Lite Machines Corona > Corona wobbling
 
 
vermontelectric
Heliman
Location: Vermont, USA

Ok...I've rebuilt this critter and have it flying, but there's a weird wobble when I apply power or make more sudden movements. It was really noticable when I attached my home brew training gear...made it almost unflyable.

In a stable hover without the training gear, it seems to level out. Tracking is ok. My gain on my gyro is all the way up for "Neutral" and "Gain". Maybe a problem there?

I'm constantly fighting the tail and a hands off hover is out of the question...even for a couple of seconds.

Guess I need to go back over my trim settings and see if I can figure it out....then get a HH gyro.

Well....at least I'm flying again...that's a good thing.

Steve Roberts
05-30-2006 Over year old.
 
 
bscfo1
Senior Heliman
Location: Tampa, Florida - USA

vermontelectric,

Is this a head wobble? What's your head speed? Too low will cause a wobble. What is the pitch of the blade arms? Maybe you need less pitch or more weight to get the head speed up. Are you using a lithium battery or the big NiCad?

Lite Machines seems to like this bird to be HEAVY.
05-30-2006 Over year old.
 
 
copterklutz
Senior Heliman
Location: Western Massachusetts

Have you balanced the Heli after attaching the training gear ?? If the CG isn't right it may wobble...






" Well, Um.... it's fixable......"
05-30-2006 Over year old.
 
 
vermontelectric
Heliman
Location: Vermont, USA

No telling what my head speed is, but the wobble seems to be consistant at all speeds. I know the shaft is ok 'cause it's new, and the wobble isn't like a vibration..the whole heli tilts from side to side..maybe 2x/sec or so. I'm using the 6dot pitch blade holders. CG looks to be ok and I'm using the big mother 8 cell 3500 NIMH's.so it's definitely heavy.

Steve Roberts
05-30-2006 Over year old.
 
 
copterklutz
Senior Heliman
Location: Western Massachusetts

Steve,

I don't know if this will help any, but I had a helluva time with my Corona not flying smooth until I noticed that the left/right cyclic servo was messed up. It was never centering itself when I wasn't giving input. It was always jumping side to side at random. How tight is your gear mesh ? The GYRO will not like vibration, and even servos can be sensitive to high frequency vibes. I used the rubber mounts on my servos and didn't snug them up too tight, and I also rubber mounted the gyro bracket....It made a huge difference for me. Something positive to try.


Matt T






" Well, Um.... it's fixable......"
05-31-2006 Over year old.
 
 
vermontelectric
Heliman
Location: Vermont, USA

I also have rubber servo mounts. I used some double sided 3M foam tape to mount the gyro.

Steve Roberts
05-31-2006 Over year old.
 
 
bscfo1
Senior Heliman
Location: Tampa, Florida - USA

vermontelectric,

How loose are the blade grips? If they are loose on spin up, they're probably lead/lag (move side-to-side) too much and causing a wobble. Tighten them up.

You can have them a little tighter then a collective pitch model and it'll be okay.

If that doesn't work, try the grips with less pitch.
05-31-2006 Over year old.
 
 
vermontelectric
Heliman
Location: Vermont, USA

Well, I realigned everything and it does the same thing.

I'm using JR nes331 servos and a Revolution 200 sport gyro.

Any suggestion for a process of elimination?

Steve Roberts
06-01-2006 Over year old.
 
 
copterklutz
Senior Heliman
Location: Western Massachusetts

Quote 
the whole heli tilts from side to side..maybe 2x/sec or so


Man, that sounds like something in the rotor head assembly is out of balance. I'd start by removing the blades and grips and spin it up on the floor and watch the rotor assembly. If it still has a wobble, then remove the flybar and spin it up again. I had an out of balance flybar that made mine fly funny until I got it balanced correctly. Those are the only two items in my opinion that will generate enough spinning mass to make the heli wobble....

If you're not too far up in Vermont, I'd be glad to help you look at it....






" Well, Um.... it's fixable......"
06-01-2006 Over year old.
 
 
vermontelectric
Heliman
Location: Vermont, USA

I took the blades and grips off. It's the shaft...AGAIN. I think I'm going to have to get the titanium shaft after all. this is getting ridiculous...

Steve Roberts
06-02-2006 Over year old.
 
 
vermontelectric
Heliman
Location: Vermont, USA

I still have the same problem. It wasn't the shaft. I think it's the Chopper1 rotor head, but I won't be sure until I replace it. They were very kind to immediately send me a new one, no questions asked. I'll try it this weekend if I have time and see what happens. I really need a new gyro though. I have the gain all the way up on my Revolution PZ200 and the tail is still wandering all the time.

Steve Roberts
06-10-2006 Over year old.
 
 
Chads
Heliman
Location: Depew, NY USA

How are you making out with your wobble. I have had the same problem I can't nail down and was wondering if my Chopper-1 rotor hub is the problem. I have tried everything but the hub...

Chads
06-17-2006 Over year old.
 
 
vermontelectric
Heliman
Location: Vermont, USA

Now I'm thinking it was the flybar and the rotor head. I put a CF blybar on and it's much better even with the original rotor head. I still haven't had the time to swap out the head. Maybe later today or tomorrow. I'll report back and let you all know.

Steve Roberts
06-17-2006 Over year old.
 
 
Chads
Heliman
Location: Depew, NY USA

I just contacted Bret at Chopper-1 and he states all of the hubs have been tested for run-out. I will wait to hear back from you as I may end up with a BT Carbon Fiber Flybar as well.

Chads
06-17-2006 Over year old.
 
 
vermontelectric
Heliman
Location: Vermont, USA

Well, after all is said and done, looks like it was a warped shaft after all and not the rotor head. Must have been warped right out of the package, because I had the wobble immediately after installing a new stock shaft. It seemed unlikely that the Chopper-1 rotor head was out of whack, but at the time, that's what it was looking like. Bret at Chopper-1 has been very helpful and patient with me and I have to say I'm loving the tail block and the boom block I got from them. I have just installed the BT 5mm Titanium shaft, so that should help as well. I'm now working on dialing in my gy401 and trying to figure out the settings on my 7cap tx.

The good news is that I'm getting closer to a decent hover...and a million dollar Corona

Steve Roberts
07-05-2006 Over year old.
 
 
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e-Lite Machines Corona > Corona wobbling
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