I have built a Comet 700 speed heli im running 2900 rpm and wow does it rock . I need to get rid of the porpoise or dolphin effect at fast speeds would I lower head gain to get rid of it ? any help would be very helpful .

You have to increase Cyclic Ring or decrease Collective Pitch range.

_________________
Spirit System developer

thanks i will try that but I need to keep the pitch at 16 degrees

This is unfortunately extremely high pitch. In other words model is at the edge of physical capabilities with current settings.
So that there is not enough room for compensating.

_________________
Spirit System developer