Collective Pitch Heli Configuration (Yaw Problems)

[mcashatt]

Thanks for looking.

I have built a TREX 450-sized collective pitch heli running on a multiwii board (ver. 2.2 of MWC). This 450 has a 4-blade scale rotor head and a 2-blade stock tail rotor. When I spool up, the heli starts spinning as if the gyro were reversed or not working.

I am running the stock PIDs except for Yaw. On Yaw, I have bumped the "P" up to 15 and the "D" up to 30. Also, I have HORIZON mode set all of the time. The higher "P" and "D" values seem to help a little, but the bird still spins like crazy. It will hover, but spin like a Chinese star so I can only get it up for a second or two.

I have triple-checked my gyro direction for the tail. It's fine. I have also checked the throw of the servo which seems ample. Any idea what the problem could be?

PS: I have heard long ago that a 4-blade head requires a beefier tail rotor to provide ample counter-thrust. Could this be the problem?

Any help is appreciated.

[Hamburger]

I had a 325mm cp heli with 4blade head for some time working with mwii. Usually you run that with much lower headspead compared to 3D-2blade setups; that leads to kinda weak tail authority. But it is nothing close to "spinning like crazy".

Is the yaw signal from the rx in mwii correct - for left rudder stick the rx-value in gui must go down towards 1000. If not, reverse signal direction in your tx.
Only then look at the automatic compensation from mwii. If it begins to "spin like crazy" then best bet is to reverse the orientation. gui has a tab for this. (if you do the reverse in config.h, then you must force a eeprom-reset or run the eeprom-clear sketch).

[mcashatt]

I had a 325mm cp heli with 4blade head for some time working with mwii. Usually you run that with much lower headspead compared to 3D-2blade setups; that leads to kinda weak tail authority. But it is nothing close to "spinning like crazy".

Is the yaw signal from the rx in mwii correct - for left rudder stick the rx-value in gui must go down towards 1000. If not, reverse signal direction in your tx.
Only then look at the automatic compensation from mwii. If it begins to "spin like crazy" then best bet is to reverse the orientation. gui has a tab for this. (if you do the reverse in config.h, then you must force a eeprom-reset or run the eeprom-clear sketch).

Thanks Hamburger! I will try your recommendations and post back later today!