polyhedron_12

I've searched three forums looking for my question, but couldn't find a specific answer.

First off I have a nexus .30 that I bought used on ebay.

When i throttle up, i get an insane wobble for a few seconds and then it goes away. Then when i throttle up some more, the wobble comes back for a few seconds, and then it stops. Also when i throttle down it does the same thing, wobbles for a few seconds and then stops. Im also having trouble tracking my blades. I have adjusted my linkages and can't get my taped blade to drop down to the same plane as my other because when I adjust my linkages, the wobble gets worse.

So, I think it could be three things.

1. I just need to get tracked (adjust linkage until it finally tracks)
2. My throttle curve should be adjusted. (right now I have throttle and pitch curve the same at 0 25 50 75 100)
3. Something is bent

Any ideas?

Hotshot Charlie

How tight do you have the main blades in the holders? They should be pretty darn tight..... if you hold the heli on it's side and shake it, they should stay extended. (At least that is what I have been told) I am a newbie with 10 flights and after my first flight my instructor said "tighten those blades" and they are pretty darn tight now. No wobble !

gid01

A common factor of wobbling are:

1. Out of Track main blade
2. Main Blade to tight
3. Bent spindle
4. Unbalance main blade (CG and weight)

That's the usual cause of wobbling, If you are using the stock Nexus wood main blade, they are normally out of balance. There's a lot of weight and C/G difference on each blade.

powrplay

This sound like similar to the problem I'm having with my Hawk Sport. But, I called it "wagging". You may have the right discription because I'm still new to this hobby. I'm still trying to capture the video to show everybody what mine is doing. If it is similar, I'm attaching a like to my question... [link=http://www.rcuniverse.com/forum/Hawk_Sport_Vibration_Problem/m_1534504/tm.htm]Hawk Sport Vibration Problem[/link]

Everything seem to check out, blade balance (also according to the [link=http://centuryheli.com/support/manuals/1000b%20sport%20full%20pdf/step44_45.pdf]manual [/link] it is balanced).Tracking appears good while viewing it from about 15 ft out. My local hobby shop did tightened my blades the night before I last few it and it still had the same problem. As for a bent spindle, I still have to check on that. I am still using training gear...for a little while longer, that is. Or from what I've read on this forum, I may shorten the length of the rods which "reduces" any vibration anyHeli produces. This board has been very helpful!

Good Luck!

gid01

Hey Powrply, what kind of vibration do you experience? Did it happen while you're still on the ground or when you're airborne? What kind of vibration, is it "Up and Down" like see-saw or "Left and Right

If it is a vertical vibration or "Up and Down" and you're still on the ground, you have a problem with your main rotor mechanics, it's either too tight blade, unbalance blade, bent spindle etc etc. in short you have an unbalance mechanics within your main rotor. While if you're airborne and experiencing "Up and Down" vibration and still using the Training gear, I bet it's the Training gear causing the vibration. Try to shorten or stiffen your Training gear. Sometimes unbalance tail rotor blade contribute to this vertical vibration, but this only occur if you have a considerable mass difference on each tail rotor blade. Due to high rpm of the tail rotor, slight unbalance is mostly negligible.

If you're experiencing lateral or "Left and Right" vibration, Your gyro gain is not set correctly or you have too much rotor RPM. Check your Throttle/Pitch Curve and use Tachometer to correct your RPM.

Happy Flying..

Nightshifted

The vibration I had all came from the training gear. It shook on the ground only until the main
rotor blades trued. The instructions that came with it said to leave some movement in the blades at the rotor grips so that they can even out centrificaly. Once it got off the ground say about 2 feet it would then shake vilolently in the air trying to shake apart. That went away when I made a stiff training gear. I used aluminum arrow shafts and then used the fiberglass tubes as cross joiners undernieth.I preloaded them by cutting an old training gear ball in half and wedging it between the center block and the fiberglass tubes criss crossing undernieth. It still dances untill speeds of all parts is even just before lift off speed and then is nice and smooth in the air now. The big problem that I have and can't get rid of is no matter what I do I can't get it to stop sliding to the right and rotating to the left. I've been trying to fly it now almost 3 years and only once can I say I've had a successful hover.. I know I'm doing it wrong training myself but I think it should be alot more controlable than its showing me to be.

StrateJaket

I had the same problem, and just like gid01 said, check your gyro. Expecially the gain, try turning the gain down a bit, make small adjustments. When I did this it made my tail alot more sensitive to input, but no wag at all, and a very stable tail. Hope this helps..

polyhedron_12

I just kept playing wiht my tracking until it stopped wobbling. I guess sometimes other factors come into play with tracking. It took a while, but i fixed it. Thanks for the help.