The dissymmetry of lift on a conventional helicopter in KSP.

[dok_377]

I created a feedback report explaining the situation in detail. 

https://bugs.kerbalspaceprogram.com/issues/24853

[Shadowmage]

That is actually a normal effect on a helicopter. 

In a 'hover' the forces of the rotors are roughly balanced out; neither side is generating more lift than the other.

But when you start moving forward... think about it... the blades are spinning, and the helicopter is moving forward.  The blade that is advancing into the airstream (direction of travel) generates more lift than the one that is retreating.  Thus you get more lift on one side (the advancing blade), and a roll is induced about the longitudinal axis towards the side of the retreating blade.  The pilot must correct for this by including additional cyclic controls to counter the roll.

[OHara]

The question is: should KSP's Breaking Ground have a feature to help us with the mix of pitch- and roll-cyclic needed to give level forward flight ?

In physical helicopters, that asymmetric lift tilts the angular momentum of the rotor so as to lift the forward side of the disk, so the tilted disk slows the forward motion. You use mostly forward-stick to keep moving. On a physical helicopter there is an advance angle so the forward cyclic pitches the blades to give left-right asymmetry, compensating the effect in the OP..

KSP's rotor disks have strangely small angular momentum, needing rather less phase advance than the 90° in simple descriptions of helicopters (KSP-BG implemented 0°) so there a mix of significant pitch and significant roll is required for level forward flight.   

Maybe KSP-BG could add a slider to the blades to let us set the advance angle (currently 0°) but maybe that is not worth the complication.

[EnderKid2]

I'm running into a similar issue in Stormworks, where my high-speed helicopter with a pusher prop uncontrollably rolls beyond around 80 m/s due to retreating blade stall.