That is about 160 mph.
For a fairly new helicopter, around 120 knots. Around 150 mph, except for fast military helicopters.
80
That cannot be calculated without knowing the average speed over that distance.
What would you call "average". I don't see there is an "average" helicopter, all are different.
09527349074537mph
There are many different helicopter engines, most of them now jets
Cruising speed is about 150 mph.
The helicopter begins to fall because gravity is pulling its weight. As the helicopter accelerates, the air passing past the helicopter creates drag, as the helicopter continues to accelerate the drag Increases until the drag becomes equal to the weight, stopping it from accelerating. Even if the helicopter did not auto rotate it would still reach a terminal speed, however the terminal speed for the non auto rotating helicopter would be a lot higher and the helicopter would take longer to reach this speed.
Some are, yes, but not all of them. Military attack helicopters tend to be the fastest. The average speed of a formula 1 car is 230 MPH. The average speed of an Apache attack helicopter is 365 MPH.
They change the speed and angle of rotor, and speed of tail propeller.
About 200 mph.