About 170 mph.
That is about 160 mph.
What would you call "average". I don't see there is an "average" helicopter, all are different.
the average helicopter is 12.5 metres long and 3.0 metres high
That cannot be calculated without knowing the average speed over that distance.
There are many different helicopter engines, most of them now jets
Cruising speed is about 150 mph.
According to the U.S. Navy Fact File the speed of the H-3 Sea King Helicopter is 120Kts.
They change the speed and angle of rotor, and speed of tail propeller.
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.
Its average speed was 1200/7 = 171.4 mph, approx.
About 200 mph.
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.
By increasing or decreasing the speed of the tail rotors. This unbalances the torques acting on the helicopter and causes it to spin.
It's top speed is about 185 mph
What is the limiting factor for helicopter speed you ask? What happens to the rotor as the velocity of the helicopter increases? The relative speed of the tips of the rotors changes because of the wind speed. On the advancing side of the rotor the speed increases by the speed of the helicopter. On the retreating side of the rotor the speed decreases by the speed of the rotor. One of two things happens as the helicopter reaches a high speed: A: If it is a large rotor, the advancing blade will reach the sound barrier and sap energy from the rotor, slowing it. Significant damage may occur to the helicopter. B: If it is a smaller rotor, the retreating blade will slow to the point where stall occurs, and the helicopter will be forced into a turn while losing altitude and decreasing speed, then it will usually recover if altitude permits. Option B can be mitigated by increasing rotor RPM at higher speeds. In this case the rotor speed becomes the limiting factor, as the centrifugal forces at the root of the blade are quite incredible. Carter
Just keep driving around and the helicopter should back off after a while
No helicopters can break the sound barrier. The fastest speed achieved be a helicopter is 249 mph.
The top speed of a Black Hawk helicopter is up to 150 knots. However, in actual operations, the realistic top speed would be 140 knots, equivalent to 161 miles per hour.