Main rotor 'flutter'

[RaysHeli]

I have a new problem that looks like a serious unballance of the main rotor. It happens fairly often but not all the time at max throttle. I have replaced the main blades thinking they were out of ballance. I have gromets on all the links but I had them before with no 'flutter'. Nothing seems unusually loose. This started happening after I replace one main blade grip after the ball joint broke off. What do you suggest?
thank you

[TonyTypeS]

Check your swashplate. The 2 halves prob got some slop in the crash. Press it back together. Mines wa doing the same thing in flight. I used very thin CA to prevent the 2 halves from getting slop.

Also check your featuring shaft and make sure it's not bent. Theres a chance a bent shaft can cuase the blades to flutter in flight.

[RaysHeli]

Thanks for the response. Can you explain what you mean by two halves of the swach plate. It it not obvious to me what the two halves are. Is it the bottom plastic piece the servos connect to? Is that two pieces of plastic?

[IanWhitehead65]

Originally Posted by RaysHeli

Thanks for the response. Can you explain what you mean by two halves of the swach plate. It it not obvious to me what the two halves are. Is it the bottom plastic piece the servos connect to? Is that two pieces of plastic?

There are two main parts to a swash plate. The lower part that is attached to the servos does not rotate with the blades it only rocks with the servos. The upper part is attached to the blades by the dog bone links and rotates. The two parts interface at the large swash bearing. This can sometimes slip out of one or other half, particularly if a crash is involved. take the main shaft out, take off the head and take off the swash. Look at the swash carefully around the bearing and make sure the two halves are fully seated on the bearing. Some use CA or threadlock to secure the bearing. Apply very carefully with a pin and don't get it in near the bearings. I would not use CA unless it was repeated slipping though because I worry about the bearings.

Whlist you have the main shaft out check it very carefully for hairline cracks. Sometimes if you flex the shaft and examine with a magnifying glass you can see the small cracks. Next, examine the head with the magnifying glass also looking for small cracks, particularly around the damper recesses.

Good luck

[bladebuster.rc]

Originally Posted by RaysHeli

I have a new problem that looks like a serious unballance of the main rotor. It happens fairly often but not all the time at max throttle. I have replaced the main blades thinking they were out of ballance. I have gromets on all the links but I had them before with no 'flutter'. Nothing seems unusually loose. This started happening after I replace one main blade grip after the ball joint broke off. What do you suggest?
thank you

Hi, is happens something similar to me when the main shaft (CF) is fractured.

Is is something quite difficult to see unless you take it out (at least the hub), and twist by yourself (better if putting back its screw): at that time, a fracture, along the shaft axis, should/could appear, among the holes where the hub screw and/or the A-gear are screwed.

That facture introduce a torsional spring effect which resonates at certain flight conditions leading to fluttering, tail wag and so on...
hope this will help,
Luca