Hi Denis, I experienced a similar problem some time ago when I dressed an ESKY King 2 in an Augusta body. That too had a GY401 on it but I found that although the body was very light, the main motor and tail gyro/servo had more work to do because the body made the heli 'weathervane' in any wind. My 'cure' was to use rate mode on the gyro as this seems to reduce gyro and tail servo loading and I also increased the battery from a 1800 mAh 15C pack to a 2200mAh 20C one.
That worked for me but best of luck with your experiments.
Hi Barry and thank you very much for your suggestion!
Yesterday I had one more test and I finally discovered how to solve the issue :
1) Increase the gyro gain from 30 to 40 (that in case of my T14MZ + G401 gyro means quite a big increase)
2) Make throttle curve even more flat and in the range from 84 to 86%
Result : problem solved!
Sure what I did seems easy ... but I thought that after having flown 2 ears with same parameters, same hely, same batteries and setting ... putting it into a fuselage would surely not generated the need of increase the giro gain.
Instead, reality teaches that maybe the effect of increased inertia of the helicopter tail lever, maybe the area of the Ecureuil rudder shape, have made the tail system effectiveness different and more "weak "... at a such level that a consistent increase in gyro gain has been needed.
Before yesterday I've made many experiments, part of those cosnisted in decrease a little bit .. or little more ... the gyro sensibility ... never tried to "think opposite" and increase it .. it just seemed me not so intuitive and logic .... but instead it 100% was
Model now is perfect and a pleasure to fly and I'm very happy again
To finish, making the throttle curve to an almost flat line (85%) - with stock 75A Align regulator and 6s 5000 batteries I have- gives me a main rotor "tachoed" speed between 2100 to 1900 Rpm, that I think is great for a rex 600 in a fuselage.
All the best and thank you one more time for the suggestion!