My uncle Jim was one of the naysayers when I told folks that I was going to learn to fly helicopters. He voiced concern over a common misconception regarding whirlybirds; that they fall out of the sky if the engine quits. Airplanes do glide a good ways with the power cut. But they still need a runway to slide across once reaching terra firma. Don't kid yourself, it's gonna really suck if the plane you're in has an engine failure unless you're next to an airport or a deserted freeway. My advice, an extra cocktail. You can catch a cab whenever you get where you're going. If you don't get where you're going, you're gonna be in an ambulance, either way you ain't driving.
Helicopters create lift by pulling air down through the rotor. If the engine quits, air begins to flow up through the rotor as gravity pulls the bird toward Earth. Turning the rotor and the engine would take too much energy and the rate of descent would be uncomfortably high. Squoosh. The rotor is separated from the engine to solve this problem. It works the same way a bike does. Pedal for a while and you can take a break and coast with that stored up energy. If there wasn't a freewheeling unit(called a sprag clutch in a helicopter) in the bike, there'd be no coasting.
So that's all there is to it. You just separate the rotor from the engine, called an autorotation, and coast to the ground (where you don't need a runway, just a space a little wider than the helicopter). Granted, this isn't coasting like a feather fluttering but it's substantially slower than the 9.8 meters per second squared that a dropped rock achieves.
I was introduced to the maneuver a couple of days ago in 951Bravo Lima. Its color scheme is the same as my high school's, so I took that as a good sign. One of the reasons I chose this school (being in a tropical paradise was never considered, honest) is that they let all their instructors teach autorotations. Most schools only let the chief pilot teach the maneuver which means you only get to do it when you're with the chief pilot, which means not very often. I figured that it makes a lot more sense to go to a school where I have the opportunity to get really good at flying without an engine, just in case.
We climbed way up (a Frenchie set the record for highest successful autorotation to a landing in 1972 when his Lama had a flame-out at 40,000 feet and couldn't be restarted) so we would have plenty of time/distance to practice. You check that all the warning lights, instruments, and gauges read in the groovy then you count it down. "Autorotation in 3,2,1 down, right, roll, bump." Down is the collective and pushing that all the way down gives you the same little weeeeee that you feel in your belly as you slide down on the roller coaster. Right is right pedal cuz you start to yaw left when you stop producing torque. Roll is closing the throttle (I know, it does sound crazy) and bump is bring the collective up just a little bit so you don't over-speed the rotor.
I'm slowly getting the entry to the auto down. As long as I calmly countdown, it's easy as pie. The first couple were less than pretty but I'm getting better and will be damn good at it soon enough.
2 days ago