How fast can a coast guard helicopter go?

Answer

Most typical helicopters can only go about 150mph or maybe a little faster.  Compound helicopters or the V-22 Tilt-Rotor can flaw above 200mph or even 300mph.

The maximum airspeed of a helicopter is limited by the speed of the rotor blade.  The speed of the tip of the blade can not go faster than the speed of sound or it will go through the sound barrier and began to vibrate.

The rotor blade turns about 50 revolutions per second.  The further out from the center, the FASTER the rotational velocity and the faster the air is flowing over the blade.   As the helicopter moves forward through the air, the velocity of the air over the blade is the SUM of the Forward Velocity Plus the rotational speed of the blade. 

As the blade rotates around and advances from the Back of the helicopter to the forward, then it sees the sum of the two velocities.  Then as the blade continues around and retreats to the back, its velocity is the rotational velocity MINUS the helicopter's forward velocity. 

For example:  Suppose the Velocity of Rotor Blade tip (helo in a hover) = 350mph. 

Velocity of the Helicopter in flight = 150mph.

Velocity of Advancing Blade (in flight) = 350 + 150 = 500mph

This simple calculation will determine the maximum speed of the helicopter.

First answer by Custermen. Last edit by Custermen. Contributor trust: 317 [recommend contributor]. Question popularity: 23 [recommend question]