EXI 500 wildly spinning

[Gorzideudeus]

Hello.
I recently completed (or at least I think I did) my first helicopter, an EXI 500 size heli.
However, on first takeoff attempt, it began to wildly spin counterclockwise
progressively faster depending on how high it was throttled up. The helicopter wasn't even
close to lifting off when I decided that it was already out of control. I've checked my gyro,
and everything seems to be fine there. Any other ideas on how to stop this? Even with max trim, the tail rotor simply can't keep the helicopter straight.
I would appreciate any help, as I want to get this chopper in the air without breaking first.

[Diggiz]

Normaly when this happens 95% of the time its
the gyro direction.When u move the heli tail left,
the slider shud move to the right and vice versa.
What gyro are u using? Have u got the plug polarity
the right way round and in the corect spot on the
gyro?

[Solmanbandit]

Originally Posted by Diggiz

Normaly when this happens 95% of the time its
the gyro direction.When u move the heli tail left,
the slider shud move to the right and vice versa.
What gyro are u using? Have u got the plug polarity
the right way round and in the corect spot on the
gyro?

Exactly, sounds like your gyro is backwards or your setup.

[Gorzideudeus]

The gyro is sliding the tail rotor correctly according to what you said, and I think that the plug is correctly in the reciever. It is a cheap gyro (HK401B).

[Diggiz]

Oh Hk401B. That might be the problem. I had a dud one straight from HK. Did what you said. I ended up buying a GA250. Much better. Those gyros can be hit or miss. Typical HK products.

[MGPTWEGB]

The HK Assan 250's are not that bad..... Great 12 dollar gyro.

[Gorzideudeus]

Thank you all for your input (I know you all know much more about this than me) but I fixed the problem, and I don't think it was the gyro. I reversed the tail rotors and flipped the belt around so that they can push enough air to keep it from spinning. However, new problems have appeared. I took the heli outside, thinking all was well. I throttle it up, and once I get to higher RPMs, the heli goes nuts. It starts violently shaking, it tries to tilt into the ground, and it will not take off when it is completely throttled up. I couldn't keep it throttled up long as I was afraid that it would shake itself apart. So maybe this is another mechanical error? Are my cyclics incorrectly set up? Are my main blades not tilting enough to achieve lift? Why is my helicopter shaking like a paint shaker at Home Depot? And I don't think my main shaft is bent. I think my flybars are balanced, too.
Thanks for your assistance.



Sent from my HTC DROID DNA

[treotraveler]

I think you really need to take the heli to a local hobby shop and have it looked at. I suspect you are having problems with your building experience, or lack of experience. I would really not like to find out that you or someone else got hurt......

[Gorzideudeus]

You're probably right. Unfortunately the "local" hobby shop is very far away, but oh well. By the way, when I test my heli I do it in a remote location and I stand very far away, so the only thing in danger is the heli itself. But you're right, the only hobby grade experience I have is with RC cars, and that's obviously very different. I would prefer to fix my heli myself to learn more about it. If I start breaking parts, though, I'll go to a hobby shop.

[charliebe]

Did you balance your blade ? If not done yet listen to Finless build videos, there great to learn
building.

[Gladius]

I would tear the rotating pieces down, and start checking it for vibes. Start with just the motor, then add the main shaft, then the head, then the boom block, then the boom (if TT)( then the tail, then tail blades, and finally the main blades. That will help you pin down the trouble spots.

[Gorzideudeus]

"I would tear the rotating pieces down, and start checking it for vibes. Start with just the motor, then add the main shaft, then the head, then the boom block, then the boom (if TT)( then the tail, then tail blades, and finally the main blades. That will help you pin down the trouble spots."

Wow, good idea; I didn't think of that.

[Gladius]

There are so many things that can cause problems on these helis. You have to have a method to search for them.