A friend calls me the other day and asks an interesting question, "can a helicopter land without power?" My initial uninformed answer was "no way", it would fall like a rock. Too busy at work lately to strike out on the internet, he asked around and comes back to me with the impression that it can land powerless from a discussion he had woth a coworker. Anyone ever thought of this or figured it out? I just do not see how logically a helicopter can lose power and still have any sort of lift. Interesting question that I would like to know the answer to...... Maybe i need to try howstuffworks.com Time restriction, I actually have work to do at work, sounds weird huh....... Josh
Well - quick answer is: Autorotation "Autorotation" is the term used for the flight condition during which no engine power is supplied to the rotor system and sustained flight is possible from the rotor blades. The pilot can use the inertia for collective pitch to slow the rate of descent and effect a safe landing. Unlike fixed wing aircraft, rotor wing aircraft are capable of controlled landings during most conditions when power is lost; assuming a suitable landing surface exists below the helicopter. Helicopter pilots often train in autorotation landings. Height-Velocity Chart Each helicopter flight manual contains a "Height-Velocity" chart, which indicates speeds and altitudes to be maintained so that a safe autorotation may be made in the event of a mechanical or electrical failure. At speed/altitude combinations below the curve in the "caution" areas of the chart, the helicopter would be difficult to safely autorotate. For this reason, the Height-Velocity Chart has been given the nickname "Dead-Man's Curve." That should be enough to put your mind at rest... Rich
Richards autorotation description is right on - there are people practicing it over my house every weekend (we are half way between Buchanon & Napa - a very popular training route). The helicopter just becomes an expensive autogyro glider when power is pulled, no loss of control. I'd love to see a V22 autorotate though!
Mr. Wallace, Wow Great response, thats what I was looking for. Very interesting indeed, they say you learn something new everyday. I don't see how if they don't come to F'Chat.... Cheers, Josh
I really cannot add much to Richards response, good job. I am currently helping to design an autogyro for a freind of mine. The principle behind the autogyro is autorotation. They are much like a helicopter in that they have a rotor which provides lift. The difference being that the rotor is unpowerd. It is made to spin through aerodynamic forces alone (autorotation). The power for the aircraft comes from, in my case, a rear mounted pusher prop. They're interesting aircraft which I knew very little about before I started designing one. This is a typical autogyro layout. Image Unavailable, Please Login
In the one lesson that I have had in a helicopter, prior to completing my training for my private license in fixed wing craft, the instructor said that, if you are moving forward when the engine fails, autoregulaton will allow you to maneuver, but make your decisions in a timely manner. If the helicopter is hovering when the engine fails, with no forward motion, you're going to drop really fast. Seems simple enough to me.
This reminds me of a time when someone looked at a Mooney M20C and asked how such a small prop could hold up the aircraft. I asked if he had noticed those two things on the sides we call "wings". An airplane is called a "fixed wing" aircraft, and has to be moving forward through the air to get airflow over the wings to get lift. A helicopter is a "rotary wing" aircraft, and the rotor blades have to be moving through the air to produce lift. Of course, lift also produces dynamic drag (in addition to basic airframe drag), so without power, the trick is to not run out of wing motion too soon.
Autogyros are so damned cool. I have very few goals on "what I must own in my life" but an Autogyro is on that short list.
