how fast are helicopters?

Question

like the ones that cover car chases?

Answer 1

The world recorde setting speed for a helo is 249.10 mph.

The most helicopters that film for TV stations are Bell jet rangers. They can manage a max of 139mph

Answer 2

Most have already answered the how fast part so I'll tell you what limits a helicopter's speed. rhsaunders is on the right track but the speed of sound has nothing to do with it. Unlike an airplane which stalls at a relatively low speed, a stall occurs in a helicopter at high speed. We call it "retreating blade stall" and that is what limits the max speed of any helicopter. What happens is that the faster we go, the bigger difference in speed between the advancing blade and the retreating blade. Let's say we're doing a hundred knots through the air. That means that the blade that is moving forward, advancing, is flying in a hundred knot head wind and the blade moving backward, retreating, is flying with a hundred knot tail wind. That's a two hundered knot difference in airspeed as far as that blade is concerned. A rotor blade is like any other airfoil in that the faster it travels through the air the more lift it produces for a given angle of attack. Since the advancing blade traveling at a much higher speed is producing so much lift, the retreating blade now must increase it's pitch angle to a higher angle of attack to match the lift and keep it equal on both sides of the rotor disk. But like every other airfoil, there exists a critical angle of attack where the airfoil will stall. So the faster you go in a helicopter, the bigger the difference in airspeed between the advancing and retreating blades and the closer the retreating blade gets to that critical angle of attack. Try to go any faster, abra kadabra, retreating blade stall happens and if you were flying along bored before things just got real busy in the cockpit.

Answer 3

The news helicopters will average anywhere between 110-140 mph, depending on the make and model and the conditions of the day. Some can go faster, some slower. Wind is a factor for following ground vehicles because if the helicopter is fighting a strong headwind, it will travel much more slowly. Helicopters will always have limited speed for the reasons John B gave. Charles M gave you the speed record.

My apologies to eferrell, but retreating blade stall will not occur at the same speed every time. It is a function of angle of attack, just like in airplanes. If you are flying on a relatively hot day, for example, you will be pulling more collective pitch to achieve the same result. More pitch means more angle of attack, which means that a retreating blade stall will occur at a slower speed on that day, all other things being equal.

The Rotorcraft Flying Handbook lists the following possible causes/contributing factors for retreating blade stall: high forward airspeed (this is the main one), low rotor RPM, high density altitude, high gross weight, turbulence, and abrupt maneuvers.

Answer 4

How Fast Are Helicopters

Answer 5

Jetranger could do 140 MPH probably, fennec/ecureil and that family maybe even 160 MPH
fastest up to day is military Lynx British origin helicopter. dont know the number but it is big.
pretty fast is Mi 24 it does 180 MPH.

John B you teoretize very well but that is no answer to the question stated.

Answer 6

John B explained pretty well about retreating blade stall, but is wrong about stall speed of a fixed wing. A fixed wing aircraft will stall at any speed or attitude if the critical angle of attack is exceeded. Since helicopter blades turn at a maximum fixed speed, retreating blade stall will occur at the same forward speed every time.

Answer 7

Not very -- a bit over a hundred knots is usually the upper limit. The problem is that the forward-moving rotor blade approaches supersonic speed at its outer end, while the rearward-moving blade, moving at a much lower relative airspeed, produces much less lift.

Answer 8

What bird are we talking about? An Iroquois UH-1 will do 150 MPH in a pinch.........