Belt CP Tail Spin

Hey All,

I had a hard landing that resulted in a blade-boom strike. After replacing the blades, I have an uncontrolled CCW spin. A little searching online shows this a common problem, but I have tried the solutions I found on other forums and it hasn't fixed it yet.

Here's what I've tried:

1. The servo is still pushing in the correct direction.
2. The tail rotor is still spinning CCW, face on.
3. The belt is not slipping. If you turn the tail rotor the main rotates smoothly along with it.
4. The boom was slightly bent and you could hear the belt hitting the side, so I straightened it and all runs smoothly now. It did also break one of the Knight struts, which I did not fix.
5. I moved the servo backwards and forwards a few millimeters thinking it might have slipped. Neither direction solves the problem.
6. I moved the servo arm as far forward as it will go. It will stop the movement, but the heli can only turn CCW.
7. Full trim tab to the right on the transmitter helps but does not solve the problem.
8. My HH gyro is steady red before I spin the bird up.

Any advice is greatly appreciated.

Writerrhino

This probably isn't it, but I had this problem once. Check the tail rotor servo rod, and make sure it is not loose in the ball link fittings on each end. I had mine to become loose and the rod had pulled partway out, effectivly lengthening the rod, causing the heli to yaw, I believe it was ccw. Anyway it got nose in on me before I realized it, causing me to loose orentation, causing a crash.
I repaired it by super glueing it and pushing the rod all the way into the fittings, and then readjusting the tail.
Maybe that will help.

Donnie D

Donnie,

Yeah, I saw your earlier post on this subject and had already checked that; no joy. I'm gonna email Nutcase directly and see what he thinks. I'm wondering if I need a new main gear. Mine's looking kind of worn and I know that low head spped is a sometimes a factor in tail spin.

Thanks for answering my post.

Writerrhino

First, Why do you think your head speed is now low? I would put the gyro in rate mode to try and find whats wrong, /HHmode will hide things. Once it rate mode start from the beg. just like your setting up a new gyro. Have you checked to make sure you did not strip your tail rotor servo?

Check the tailshaft and that little wheel on it that's be driving by the belt.
I had it once with my belt-cp, this little wheel was broken and the tailshaft turns slower than that little wheel. I hope you understand what I main because my englisch is not that good.

Another things to check is make sure your tail belt isn't too tight. What kind of gyro are you using. I had some cheap ones dies after light crashes so that could be the problem there. Got any way to try another one or have someone test your gyro on their heli?

Fatdaddy wrote:

First, Why do you think your head speed is now low? I would put the gyro in rate mode to try and find whats wrong, /HHmode will hide things. Once it rate mode start from the beg. just like your setting up a new gyro. Have you checked to make sure you did not strip your tail rotor servo?

Fatdaddy:

1. I don't think my rotor speed is low, but my main gear is a little worn and I was worried that a worn gear might cause that problem. Just fishing for possibilities.
2. I didn't know that about HH gyros. I'll try fiddling in rate mode and see what happens.
3. I don't think the tail servo is stripped, it responds smoothly, it's just like there's not enough travel, which I know can't be since it flew right previously.

You guys keep suggesting, I'll keep trying!

Writerrhino

djem wrote:

Check the tailshaft and that little wheel on it that's be driving by the belt.
I had it once with my belt-cp, this little wheel was broken and the tailshaft turns slower than that little wheel. I hope you understand what I main because my englisch is not that good.

Djem,

I just checked that. I can turn the tail rotor and the main rotor spins smoothly along with it, there's no slippage. So I don't think that's it, but thanks for the suggestion!

PS: Your English is a lot better than my German!

Writerrhino

Nuttcaze wrote:

Another things to check is make sure your tail belt isn't too tight. What kind of gyro are you using. I had some cheap ones dies after light crashes so that could be the problem there. Got any way to try another one or have someone test your gyro on their heli?

Nuttcaze,

I'm using an ESky EK2-0704B HH gyro. If the light turns steady after warm-up, does that mean it's good? Also, if it starts flashing in flight, does that mean it's "lost its way"? I get both indications.

I still have the stock rate gyro that came with the RTF package. I'll swap that out and see what happens. Good idea.

Thanks!

Writerrhino

Any imput(from the TX.) will cause the light to flash.

Fatdaddy wrote:

Any imput(from the TX.) will cause the light to flash.

Okay, Fatdaddy, good to know. Almost any heli fact is new knowledge to me at this point.

Well, Nuttcaze, I tried my old rate gyro and got the same spin, only faster, both in the Normal and Reverse (WAY faster!) settings, so no joy there.

Have you ever heard of a worn main gear being a culprit in Belt CP Tail Spin? Mine got "Idle Upped" accidentally and the teeth are a little blunt. They still turn smoothly, but it makes a little more noise than it used to. Also, I held the chopper over my head and throttled up (not safe, I know) and it really seemed to be twisting hard in the same direction of the spin. In your experience, could something in the drive train be causing this?

I'm willing to try just about anything, I just don't want to buy parts blindly and swap out the whole chopper a piece at a time.

Thanks!

Writerrhino

Could you try something? Get in rate mode, on the gyro there is a switch for direction, move it to the other position. Just try that.

Fatdaddy wrote:

Could you try something? Get in rate mode, on the gyro there is a switch for direction, move it to the other position. Just try that.

Fatdaddy,

Yeah, I tried that when I swapped out the HH gyro for my old rate gyro to make sure the gyro wasn't the issue, as Nuttcaze suggested. It spun just the same, but when I switched from Normal to Reverse setting, it just spun a LOT faster.

I'm thinking something in the drive train is the culprit, because when I held it up and spun it up to about 25-50% throttle, I was sensing way more torque than a little rotor could counteract, IMO.

Keep suggesting, I'll keep trying!

Writerrhino

AH,,,, You want to overnight express the thing to NJ????LOL LOL Dude, I just don't know.... I'm gonna think about it some more....
Sorry

Rhino, check to make sure your blade grips on your tail case aren't binding. Without throttling up, move your stick back and forth and check to see if there is any binding anywhere in there. Or if your tail shaft is bent. Also make sure your tail is perfectly straight.