Originally Posted by
ATVAlliance
To check gear mesh...take a standard piece of notebook paper and cut a long strip...say 5 or 6 inches in length by say an inch wide. Double this paper over "lengthwise" so you end up with a 5 or 6 inch by 1/2 inch strip (folded).
Run this paper through your main gear and pinion. It should come out looking nice and straight with no left or right curve to it and also "accordion" like in appearance with NO HOLES or TEARS. If it is barely ruffled (like the potato chip) then your mesh is too lose. If it is severely ruffled and pulls to the left or right with actual tears in the paper...your mesh is too tight. Given your symptom, I think the later is not the case here.
Back to another possible issue. Have you checked the motor timing on your ESC? Sometimes when the motor timing is not set correctly or the ESC doesnt have an automatic timing...this can cause a loud "shrill" sound which could be confused as a "grinding" sound. If you check your gear mesh and it looks to be okay...this would be my next step in the troubleshooting process.
goodluck
Thank you for the advice ATV! I learn something new every day. My mesh seems to be ok, if anything a little bit on the loose side. I got it as tight as I could.
I have a CC Phoenix HV 85. Went through the manual and it is factory set to have auto timing on. Went through all the settings and reset everything to the way it should be just to make sure. Went outside and flew, the problem persists.
I can describe it in a little bit more detail though- normal "scale" operation with smooth increases and decreases of throttle causes no problem at all. If I increase the throttle more rapidly, I hear a noise that sounds like severe binding and the motor slows to approximately 20% output. The heli will drop quickly unless I IMMEDIATELY reduce throttle. If throttle is reduced in time, the motor spools back up quickly and flight is maintained. If I'm unable to save it in time, the heli will go to the ground no matter the throttle movement. Once on the ground, it will stay there with the blades still being spun by the motor and the whole contraption sounding like it's having an awful time provided that throttle is not reduced below about 40%. If I increase throttle while it's on the ground, there is no change in motor speed (not sure about pitch). If I decrease motor speed, once passing ~40% it will decrease gradually and stop at zero, then let me spool it back up again sounding much better. Rapidly decreasing throttle in flight does not have the same affect (thankfully!). After a few minutes of testing, I took the heli inside and found no signs of damage to any gears.
I'm beginning to suspect my motor. It's an old Align BL650L 1220K and I've heard nothing but bad things about them! I will remove it tonight and see if I can get the case off and find anything suspicious. Thanks for the help so far guys, hopefully with your help I'll be able to fix this and get my bird in the air again!