I cant believe it happened again.
A few weeks ago (as i posted at the time) my venture 30. tt39, csm180 gyro, suddenly started spinning out of control whilst in hover causing a lot of damage.
SO I replaced gyro with csm200hh, new batt pack (1500mah), sent servo away for testing, new boom, tail linkages, rudder shaft & lots of other bits & pieces. (I know the gyro's no fut401 but they are supp. to be ok on small stuff.)
After setting up gyro gain to just below tail wag in f.fwd flight, had several good flights. Then today i gave it a sharp rudder input during hover. I turned right, it flicked back left then just kept going round and round same as last time. I'm pulling my hair out (well the heli nearly did it for me it came that bloody close i had no choice but to run for it)[X(]
This is what i do know:
- Theres no binding on rudder control rod(replaced)
- The rudder shaft is lubricated and doesnt bind at end points
- the gyro is NOT reversed
- It was not a glitch
- The batt pack was FULLY charged
- The belt was tight and hadnt slipped
- The drive gears are ok

I do have some trouble with the tt39 getting hot/losing power in last 1/4 of tank, but both times tank has been 3/4 full, eng. temp. ok. It just completely loses all tail control with two different gyros.
Anyone know whats going on here? Really appreciate any help.
thanks
JA

If you're confident that it's not an electrical problem, you need to go over the tail rotor drive system very thoroughly.

What does the Venture use for tail rotor drive, anyway (belt, shaft, or tube)? The problem could be that the tail rotor is losing power, the gyro can't compensate if the tail rotor rpm's are dropping off.

Ben

On the raptor, I see the brass insert come out of the Y coupler that controls it on a lot of machines. Might be loosing your control linkages somehow. I don't know how that one is set up, but it sounds like your loosing control that way. Could also be the gyro. I have a friend that has lost a few gyros. Switched to futaba and hasn't had the problem.

It sounds to me (although difficult to tell from a written description) that you have some sort of tail drive problem.

How do you know that the belt hasn't slipped (at either end)? Are you sure that the gears are OK and not slipping? Are you sure the tail is assemled correctly and that the tail hubs are not able to rotate on the shaft?

It is not unheard of for new equipment to be faulty. CSM in the UK have facilities to test equipment and their service is first class. Their gyros have a very good reputation though and it is unlikely that this is the problem. My guess is that your problem is elsewhere. If it flies OK for a while then it is not your gyro or servo reverse settings.

Thoroughly check all components in the drive system before anything else.

Just had another thought. Does it always happen when you put in large right turns in? I guess it may be possible to stall the tail rotor blades although I have never heard of this on a model.

Thanks for your help,
Just been over it, all tail controls smooth and correct. gear def. not slipping, hub's not rotating(this has happened before).
Yes this does only happen when i give sharp input on rudder.
I did however notice that i was only getting approx 30 deg right and 45-50 deg left on the servo, allowing for the fact it " holds to each side when stationary". So I hooked the servo direct to the rec. and it centered to the left. Repositioned arm so now i get 45deg each way with gyro hooked up. maybe i wasnt getting enough travel to compensate?
It could be a drop in tail rpm but cant detect a change in the head speed when it happens. I do know it loses power as it gets hotter. Having a scale body doesnt help i suppose.
Thanks again
JA

You can get a drop in tail rotor rpm without getting a drop in main rotor rpms. You need to go over the entire tail drive system and chack that all the gears, pulleys, belts, shfts, etc. are secured properly. Look for loose set screws, those things can work loose if not loctited.

Even though you sent the servo in for service, you might open it up and make sure all the gears are OK. If you've got a tooth or so missing, you could have intermittent slipping in the servo.

Ben

It could also be a Radio Problem(i'm not sayin it's a glitch). Check your ATV, Dual Rates and all that other hopy pocky stuff that assignes funtions to the tailroter. I am not excluding the fact that's it could be a mechanical error either.

Thanks to all.
Weather permitting i'll fly it on sunday with fingers,toes and everything else crossed. Think i may even dust off the training undercarriage if i can find it.
I've been over every nut, bolt, bearing etc. Checked all radio settings atv,rates etc.
One other thing mentioned in the gyro manual was static discharge generated by tail belt. Anyone experienced this? If so how would you earth the boom or isolate the gyro or whatever has to be done??
Just wished i could have found something wrong with it, would have at least put my mind to rest. I know i'll be shakin like a newbie tho, especially after the last free haircut it nearly gave me
Let you know how it goes
thanks again
JA