i am confused , just for the record
in a r22 and most other small helis any zero airspeed and vertical decent with no engine to the ground above say 6 ft you are going to bend something
if your talking about going vertical / backwards / s-turns / 360 /180 or just plain straight in in the auto , remember you must have the indicated airspeed to be able to flare , and reduce the rate of vertical decent ,at the bottom , this is done at approximately anywhere from 100ft - 200ft . depends on where you want to end up
there is no vertical straight down with no indicated airspeed and safetly pull of a touch down auto , from height .
If someone wants to argue this please bring your video camera