GipsyMagpie
Blow back of disk
The blowing back of the disk mainly depends on two parameters:
1. forward speed
2. coning
If you reduce collective, you reduce the total force on the disk and the coning reduces.
There is also a more detailed (flapping-geometry-precession etc.etc...) explanation of that phenomenon, but it may be as convenient to remember this more simple and still correct 'umbrella' reasoning. Note that if for some weard reason the rotor would cone negatively, then it would blow forward just as an umbrella would do...
delta3