Out of the curiosity, I made a simple Hokum helicopter test.
The real deal
My test version
Playable blend file with same old terrain&sky(~6M)
Mouse up/down = pitch
Mouse left / right = roll / strafe
Mouse wheel up/down = collective / lift
Mouse LB = yaw left
Mouse RB = yaw right
I plan to do a four axis joystick version from this
How to make that slow parenting for the camera?
How to limit the camera min / max pitch angle despite the parent object world angle ?