Wobble around mainshaft after liftoff

Wobble around mainshaft after liftoff
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Wobble around mainshaft after liftoff - 7/2/2008 6:12:41 PM

dicharry

Posts: 201
Joined: 2/6/2005
From: Franklinton, LA, USA
Status: offline

My 450 is wobbling around the mainshaft axis after take off. I am hung up on center of gravity as the issue since it flies more stabely with a heavier battery although if I touch down briefly or let the tail fin touch the ground and throtle up it will spin about the axis for a few seconds before it stabilizes again. I'm hoping someone has had a similar problem and found the cause. I don't believe it's a bent main since it will eventually stabilize with the heavier battery. I've checked the CG and it seems to be right on the main shaft and with the smaller battery, just a tad tail heavy.
Thanks,
Don

Post #: 1

RE: Wobble around mainshaft after liftoff - 7/2/2008 8:45:35 PM

DumbDawg

Posts: 674
Joined: 3/11/2008
From: Osoyoos, BC, CANADA
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Plastic or cnc head??? Plastic is sloppy and will wobble but cnc shouldn't cause that much wobble. If you've had a crash lately I'd say the main shaft is slightly bent. The reason it stabilizes after a bit with a heavier battery is just that. The heavier battery is harder to throw around and so will counteract the changes with the wobble somewhat.

If you have cnc head then def its a mainshaft. You sometimes have to reverse your thinking and try to remember when it started. Just after an 'event' or a part change??? Then suspect that either the part is off or the crash etc caused more damage than you realised. What about blades and thier cg?? Belt tension may play a part too

food for thought

happy day

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RE: Wobble around mainshaft after liftoff - 7/3/2008 1:41:46 AM

Empty Wallet

Posts: 249
Joined: 1/2/2008
From: Hackettstown, NJ, USA
Status: offline

quote:

ORIGINAL: dicharry

My 450 is wobbling around the mainshaft axis after take off. I am hung up on center of gravity as the issue since it flies more stabely with a heavier battery although if I touch down briefly or let the tail fin touch the ground and throtle up it will spin about the axis for a few seconds before it stabilizes again. I'm hoping someone has had a similar problem and found the cause. I don't believe it's a bent main since it will eventually stabilize with the heavier battery. I've checked the CG and it seems to be right on the main shaft and with the smaller battery, just a tad tail heavy.
Thanks,
Don

Bent main shaft
Bent feathering shaft
Head not balanced
Blade balance
All things that I would check

(in reply to dicharry)

Post #: 3

RE: Wobble around mainshaft after liftoff - 7/3/2008 2:54:58 AM

dicharry

Posts: 201
Joined: 2/6/2005
From: Franklinton, LA, USA
Status: offline

Here's a description of the heli, and this is the first time I've flown it since I purchased it. Absolutely no crashes.
http://www.rcuniverse.com/market/item.cfm?itemId=392693
Don

If you look closely, you will notice that care was taken not to get the entire head assembly in the photograph. It is definitely a knockoff- the Align logo is not embossed on the head. This heli has been impossible to trim out to hover anywhere near as steady as my Blackhawk 450. This thing is all over the place and the swashplate is noticeably tilted right and forward at the end of the flying session. Starting out with a level swash results in the heli flying hard left and rearward. I got suckered on this purchase.

< Message edited by dicharry -- 7/3/2008 3:35:05 AM >

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Post #: 4

RE: Wobble around mainshaft after liftoff - 7/3/2008 4:46:15 PM

DumbDawg

Posts: 674
Joined: 3/11/2008
From: Osoyoos, BC, CANADA
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Did you pay the full 350??? Its gonna hurt some but you can still make a good heli out of it. But it i gonna hurt, $100 for sure for a new head unless you can MAKE the head work on that one. AND you probably gave the guy a good rating too because he delivered it fast. Lesson #1... always check the item out first before you give ratings... Once rated you got no leverage at all. But it doesn't hurt to find out if you can still post an additional comment. IF you can you go back to the guy, ell him ur gonna post the comment unless he takes the heli back because of misrepresentation. IMO

oh well... happy fix'n

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RE: Wobble around mainshaft after liftoff - 7/3/2008 5:11:11 PM

blk822

Posts: 483
Joined: 8/13/2007
From: Kent, WA, USA
Status: offline

Make sure the bolt for the head is tight.

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Post #: 6

RE: Wobble around mainshaft after liftoff - 7/3/2008 10:16:01 PM

dicharry

Posts: 201
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From: Franklinton, LA, USA
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Thanks DumbDawg. I gave $280 plus $20 shipping. The reason I didn't get to check it out sooner is because I spent 3 weeks in the hospital with a fractured femoral neck (broken hip). For 4 weeks after I was going through rehab physical therapy. Anyway, the description sounded so good, I figured this guy has really put together a good package -CNC head and tail , HS65MG servos, LT 2100 gyro and futaba tail servo and all tuned in. It sounded good. Oh well, it won't be the first or last time I get burned buying on RCU.
[image][/image]
Ignore the picture. I was seeing if I could upload a picture and just used an existing picture of my MZP
Don

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< Message edited by dicharry -- 7/3/2008 11:15:15 PM >

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Post #: 7

RE: Wobble around mainshaft after liftoff - 7/4/2008 6:57:07 AM

Zimatosa

Posts: 616
Joined: 2/7/2008
From: San Jose, CA, USA
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I kind of have the same thing happening to my heli. I was told by a reliable source to move the swash up the shaft a few millimeters and redo all the linkage to accommodate the new swash position. I have not done this fix yet so I do not know if it is the prob or if it will work. It has something to do with the swash's weight distribution being off near the bottom of travel. I get my new servos tomorrow( I hope) and I will do all the head work at the same time I install these. I'll also find that post for the fix and post it word for word. If you want to try it, it will be from a true master..and not my recollection...

Z

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RE: Wobble around mainshaft after liftoff - 7/4/2008 7:29:05 AM

DumbDawg

Posts: 674
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Oh man... broken hip and surgery.... wowsers. I don't think you can be faulted here because its obvious the guy was try'n to pull a fast one and did succeed... What goes around comes around IMO and he will one day get his. Hopefully worse. I think we've all been taken, skunked and burned at one time or another when dealing online with others. Some people have no Honor, even in the world of heli's.

Better days ahead...

Happy fly's and smooth sail'n

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RE: Wobble around mainshaft after liftoff - 7/4/2008 4:29:51 PM

dicharry

Posts: 201
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From: Franklinton, LA, USA
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Thanks DumbDawg. At least I have several other helis to fly. It's just that I'm not the kind of guy that can sit still knowing one is not flying properly. I could never in good faith sell this heli, but looking on the bright side, it has some worthy components

(in reply to DumbDawg)

Post #: 10

RE: Wobble around mainshaft after liftoff - 7/4/2008 6:56:25 PM

DumbDawg

Posts: 674
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From: Osoyoos, BC, CANADA
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I hear you on that... I have to have my two helis fly'n right or I'm not happy. And the dud you got, well like you say its a good start. Just to bad there are jackass's out there with no scruples. Oh well.

happy fly'n

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RE: Wobble around mainshaft after liftoff - 7/5/2008 9:40:04 AM

funflier

Posts: 771
Joined: 11/29/2004
From: South City, CA, USA
Status: offline

on Ebay now you cannot just make a negitive feedback you have to give him a rating now. If you paid with paypal and you get back to them both him and paypal right away you may be able to do something. I had someone sell me a bad Speedo for my 68 Porsche and I went back to him about it he said it worked when he pulled it, yeah worked but not correctly and screeched like heck. Went back to paypal and they did something was told to send the speedo back and paypal refunded my money.

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Post #: 12

RE: Wobble around mainshaft after liftoff - 7/5/2008 7:36:23 PM

Zimatosa

Posts: 616
Joined: 2/7/2008
From: San Jose, CA, USA
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quote:

ORIGINAL: funflier
I had someone sell me a bad Speedo for my 68 Porsche and I went back to him about it he said it worked when he pulled it, yeah worked but not correctly and screeched like heck.

Come on, we all know the Speedo was for you...You returned it cause you didn't realize that it would floss your pancreas when you dove in the pool...

Z

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Post #: 13

RE: Wobble around mainshaft after liftoff - 7/6/2008 9:39:39 AM

funflier

Posts: 771
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From: South City, CA, USA
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uh speedo as in speedometer as it is called in the book, no longer made and very expensive to repair or replace

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King ll, 3800w/11t, cnc head, custom cnc/trextail, 43t ,Turnigy 40A ESC/UBEC bult in, Telb gyro, Dx6i w/6100e RX, HS-65 serv

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Post #: 14