how do helicopter land when their engine dies?

Question

a plane can glide it down but how about a helicopter...

Answer 1

Autorotations are used in helicopters to perform power off landings from altitude in the event of an engine failure. During an autorotation, the main rotor is not driven by a power plant, but by air flowing through the rotor disc bottom-up (imagine a windmill) while the aircraft is descending rapidly. About as much buoyancy is provided as a round parachute of the same diameter. The power required to keep the rotor spinning is obtained from the aircraft's potential and kinetic energy. An important contributing factor is the rotor's inertia. The descent is at a normal and familiar glide angle to a suitable landing spot assuming the flight plan stayed within gliding distance of a suitable landing spot.

Autorotation is also used in autogyro aircraft as the main means of achieving lift during normal operation.

ADDED: click here for a more detailed explination.
http://en.wikipedia.org/wiki/Autorotation

Answer 2

OH MY GOD!!!!! I didnt know that there were that many people that didnt have a clue. The gent above with the long ans. has it right for the most part. The thing that is sad to see is that everyone thinks you are going to bend the heli. A properly performed autorotation is a nice soft landing. to the untrained eye it would look like a normal landing from a pilot in a hurry. I have performed over 300 Full tuchdown autorotations and have not once damaged a helicopter. If a Commercial helicopter pilot cant autorotate to a spot and land a full touchdown autorotation without damage he has NO business being in the helicopter and needs to kick his instructors butt. My Source.....I am a CFII Rotorcraft and have been an instructor. I now run a helicopter business and every month my pilots have to take me out for a flight in which they have to perform a full-to-the-ground-autorotation. If they cant do it on the first shot they are off the flight book untill they are brought back up to standard.

Answer 3

Mr KnowItAll is spot on. I sat and watched a small helicopter practice autorotations one afternoon, they don't usually end in a crash, you just need a bit of altitude and a place to land. When the power fails you just drop the collective pitch and put the nose down a bit to maintain air speed then glide to your selected landing site and flare the landing. As you lose speed close to the ground you can pull in a bit of pitch again to generate lift from the rotors as they spin down.

Obviously it's a once only deal. Timing is critical and you don't have time to change your mind one you are committed to a landing spot. This is a regular part of helicopter training.

Answer 4

on the way down the pilot changes the angle of the blades so the aircraft moving down accelerates the blades, then at the last moment before hitting the ground the pilot again changes the angle of the blades to produce lift (which was built up as the plane moved down toward the earth and the blades acted like a fan moving through the air)and slow down before touching down. if done right its a soft landing, but the pilot has only one shot. if you hold a table fan or a small desk fan in your hand and move it through the air it will spin, same as the aircraft falling. then turn the fan in the other direction (the blades on a chopper can change angles over a wide range (over 90 degrees) it will produce a force in the opposite direction for a moment or untill the rotating blades loose momentun.

Answer 5

It's called auto-rotation, using the air as the helicopter descends to keep the main rotor turning, and breaking the fall. The 'landing' will still be quite hard but the helo will not freefall.

The best example of this is those leaves that spin to the floor as they fall from trees

Answer 6

A helicopter actually glides better than a fixed wing aircraft, but not for as long. When you see a helicopter land, pay attention to how long it takes for the rotors to stop turning. This long time turning provides enough momentum lift and control for a chopper to land safely.

Answer 7

The plane can glide, and helicopter's blades can do something similar, it's called auto-rotation.
have you ever seen Acer(Maple) seeds, they do almost the same thing(the video is about a toy that do the same..)

Answer 8

If the helicopter is not very high up it can come down, however it will be a very hard landing. The higher up the helicopter is........there will be no hard landing, just a flat out crash. Hopefully the people on the helicopter are well trained and have parachutes. Often times helicopters go into a spin when the engine dies and have a tendency to flip to one side.
Making it practically impossible to get out alive.

Answer 9

By a process called auto rotation. Basicilly you put the transmission in neutral and let the spinning rotor provide the lift to slow your descent. You will still make a hard landing and damage the aircraft, but you at least have a chance at survival as opposed to falling out of the sky.

Answer 10

Amazingly, the helicopter will still take the occupents all the way to the scene of the crash- although I wouldn't call it a landing.

Actually- it depends on what type of chopper it is. Some choppers such as the ones used by the N. Guard actually have twin engines and so they are the lucky ones which can still land -

*a normal chopper above anything over ten feet high would be very dangerous to be in if the engine would fail. no engine, there is no control, no control , no landing - basic physics 101.