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RE: Heli wobbles during flight - 7/7/2010 3:53 AM   
john josey


 

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Status: offline 		I think there ok, but thanks anyway.

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RE: Heli wobbles during flight - 7/7/2010 6:19 AM   
karlik



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quote:

ORIGINAL: john josey

Normally that kind of wobble is caused by too low a head speed. Do you have a throttle curve or even just a hovering throttle adjustment on your TX ?

           Let us know how you get on

                                               cheers
                                                      john


For crying out loud guys, read the thread. It's a 4 channel fixed pitch heli. Mine cost 90.00 new including the radio. There is no throttle hold. There is no collective. There is no throttle curve. There is no expo. There is no mixing. There are 4 channels . To go up you make the motor go faster, to go down you make the motor go slower.

This where I keep my blade tension - http://www.youtube.com/watch?v=_1yqp_jKy8A - It's a little looser than most (but not all) sources suggest. But as you can see in this video it flies just fine. http://www.youtube.com/watch?v=DLw8kipxq0I We've established that his are tighter than mine.

I don't have a wobble. I don't have vibration. And the pitch doesn't change.



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RE: Heli wobbles during flight - 7/7/2010 6:40 AM   
john josey


 

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quote:

ORIGINAL: karlik


quote:

ORIGINAL: john josey

Normally that kind of wobble is caused by too low a head speed. Do you have a throttle curve or even just a hovering throttle adjustment on your TX ?

           Let us know how you get on

                                               cheers
                                                      john


For crying out loud guys, read the thread. It's a 4 channel fixed pitch heli. Mine cost 90.00 new including the radio. There is no throttle hold. There is no collective. There is no throttle curve. There is no expo. There is no mixing. There are 4 channels . To go up you make the motor go faster, to go down you make the motor go slower.

This where I keep my blade tension - http://www.youtube.com/watch?v=_1yqp_jKy8A - It's a little looser than most (but not all) sources suggest. But as you can see in this video it flies just fine. http://www.youtube.com/watch?v=DLw8kipxq0I We've established that his are tighter than mine.

I don't have a wobble. I don't have vibration. And the pitch doesn't change.




Let`s hope he resolves the problem himself then by simply replacing the blades as you did.


< Message edited by john josey -- 7/7/2010 7:01 AM >

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RE: Heli wobbles during flight - 7/7/2010 7:29 AM   
bauerbach


 

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Status: offline 		I think (after all this I cant remember) he already said the main shaft and main gear were bent/warped. the problem was already diagnosed. He has parts on the way, and he should be all set to get back to the skies.

happy flying!

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RE: Heli wobbles during flight - 7/10/2010 9:25 PM   
J-Cube



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Status: offline 		I got the parts yesterday and I should be up and flying again today. Too much calc homework to repair it right now.

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RE: Heli wobbles during flight - 7/10/2010 10:55 PM   
J-Cube



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Status: offline 		It's still wobbling

I'll check to see if anything else needs an adjustment and I'll shoot some video in front of a gauge to see if I can detect where the wobble is coming from.

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RE: Heli wobbles during flight - 7/11/2010 1:55 AM   
john josey


 

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quote:

ORIGINAL: J-Cube

It's still wobbling [&o]

I'll check to see if anything else needs an adjustment and I'll shoot some video in front of a gauge to see if I can detect where the wobble is coming from.


I can almost guarantee if you find some way to increase the main rotor speed, your wobble (it`s normally refered to as 'nodding') will dissapear.

It maybe a tight spot in the gear mesh from a crash. It could be the motor isn`t as strong as it was for some reason or the battery is starting to tail off in performance.

Is it possible to post a close up picture of the rotor head so i can see how the 'fixed pitch' of the main blades is acheived ? What method do you use to track them ? if any.

                                  cheers
                                         john

PS. If it will give you any more confidence in what i`m saying i can try and post a short video of my own helicopter doing the same thing at will, just buy slowing the head spead.

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RE: Heli wobbles during flight - 7/11/2010 4:02 AM   
bauerbach


 

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Status: offline 		I think what your describing as a wobble at low head speed would be just an apparent misbalance or other misalignment, which shows up with low speeds because its near a harmonic for it. as you accelerate the speed, the wobble becomes more of a minute vibration, the "heavy" side(either in weight or alignment) is spinning around in all directions so quickly that the wobble becomes less noticable.

that should still be addressed though.

do not mistake wobble with incompletely expanded blades. a wobble on the first spinup is very likely as no matter how carefully you extend your blades, you arent likely to get them 180 degrees. but a few seconds of good head speed, should sort that out, and any future spin downs and spin ups should no longer have that wobble.

Now, if the wobble is so bad you cant even spin it up, then you did a very bad job straightening out the blades or something is bent.

but if after replacing the main shaft, its still wobbling...

when you look down at the head cap, does it appear to be circling around, or is it spinning straight on its axis? with a new shaft though, I can imagine how it woud be anything but spinning :/

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RE: Heli wobbles during flight - 7/11/2010 7:05 PM   
J-Cube



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Status: offline 		It wobbles no mater what my head speed is. Looking straight down on the rotor head I can see a wobble movement even with the new main shaft. It goes away at higher head speeds though. Here's the latest video, read the description on YouTube for more info. Cheers.



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RE: Heli wobbles during flight - 7/11/2010 7:29 PM   
J-Cube



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Status: offline 		Update. I replaced the new flybar paddles with the old, larger ones and now I'm finding it much easier to get into a hover and stay there but it's still wobbling in flight.

I realize that the shaking in the video I just posted is probably from ground resonance but it happened very quick and at low to moderate speeds so I know something is out of balance or misaligned somewhere.

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RE: Heli wobbles during flight - 8/31/2010 6:43 AM   
poison


 

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Status: offline 		looks as if the blades are to lose you also might want to try to track them if possible by putting some different color electric tape on the ends of the blades. I use a scale to balance my blades also make sure your fly bar paddeles is pointing same direction as the end of your blade and not fighting agasint each other

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RE: Heli wobbles during flight - 9/22/2010 7:03 AM   
RCKindaGuy


 

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quote:

ORIGINAL: Solman

It is pretty much a given to replace the main shaft on a crash.  It takes soo little to bend it just enough to wobble. 


Simply NOT true about replacing main shaft after every crash.  I have 7 differnt helicopters ranging from micro to T600 in size. I have crashed every single one of them numerous times including T600 and have yet to have had to replace a main rotor shaft for being bent. It really takes alot to bend that particular shaft psrticularly on teh midsize to the larger copters.  If you are doing that after everycrash then you are paying for the rotor manuifacturer's retirement plan.


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RE: Heli wobbles during flight - 11/19/2010 7:53 PM   
Moontan13


 

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quote:

ORIGINAL: GuitarPlayer

again, my birds do not wobble at any head speed.  I make my own balancer and always balance my blades tip to hole. Think about that next time you balance a set of blades.


The balancing method is too crude. Balancing one blade against another might get you within  .1gm. Weighing the blades individually you can get to .01gm. That might seem like overkill, but you do the blades, paddles and tail rotor and it's a noticable improvement.. I've done this with a Syma 9060, a Honey Bee and a Blade120 SR. Maybe high precision is less important on bigger blades. I suppose I'll find out when my 600 is built.

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RE: Heli wobbles during flight - 11/20/2010 12:18 AM   
bikemad


 

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From: sidmouth, UNITED KINGDOM
Status: offline 		I think it's the same as a walkera 4#, and one thing that would go on them is the part that joins the main shaft to the head, it has two arms with bearings on the end at the top and slips over the main shaft at the bottem, one of the arms can brake, it's not easy to see and as it stays in one peice you don't know when it's broken, you have to strip it to find out, also if the motor is to tight on the main gear it will have the same effect,
If it's not that then I'd fit new blades, as your is a fix pitch your blades have an attack angle, ie plus pitch which you can measure, if one as more lift than the other might couse it,
theres an up grade I did on one that I worked on that worked out well that you might want to do on your is fit a longer fly bar, it gave much more control, more solid,

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RE: Heli wobbles during flight - 5/9/2012 6:46 PM   
wolfman01


 

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Status: offline 		I'll be geting my new Trex 700E soon. Will I need to balance the head? Who makes the best balancer? Where do I buy it? Thanks. John

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