Thursday, August 30, 2012

Squeeze, Bang, Blow

"Those fixed-wing fokkers'd throw bombs at Angola and be back for sunnies and bacon by nine. They didn't know war until they got shot down and we had to rescue them. When they saw the blood dripping out the door of the bird that came to pick them up, then they realized how lucky they were to know a choppie pilot." I was sent to Jo-burg to get a type-rating in the Bell 206. My instructor invited me for a post-flight pint and that's the end of the conversation I walked in on. The gruff old man speaking was Buzz Bezuidenhout, Henley Air's lead instructor. He's flown about everything that beats the air. Buzz's been shot at, shot down, and had a flame-out or two. He's kind of the Don Sheldon of South Africa (I read "Wager With the Wind" stuck in a sleeping bag with a hot water bottle down by my frozen toes on Denali once. I highly recommend it. The book, not the frostbite.) "Nevermind what they say about bleeding off early in the flare, those things'll take a wallop straight down and you'll walk away. It rolls cuz you have energy left over and yer cooked." Barrel of monkeys, right?

The beers were educational if a bit depressing, but the course was great. In the States you get your license and can fly everything that weighs less than six and a half tons, most everywhere else, you need to get checked off before you can be pilot in command of each different aircraft.

We started off with the basics of the turbine engine, "It's just an internal combustion engine, it has the same four stages, suck, squeeze, bang, and blow. They're all happening at once is the thing." And that's it, the real mystery of how a turbine works is why it's such a mystery. It's pretty simple: air gets sucked in and squeezed through these little channels, then the air is divided into two parts. One part travels along the outside, protecting the sidewalls of the can(where the explosion takes place) from the heat. The other air goes right down the center of the can where it's mixed with fuel and bang. The ensuing explosion is forced through a turbine (think waterwheel) as it's blown out the tailpipe and that's that.

Once the novelty of starting a turbine wears off, the 206 is just another helicopter. The thing between your legs makes it go left or right and the whatchamacallit in your left hand makes it go up and down. There are some differences of course, like it's more important to stay ahead of the aircraft with a turbine cuz it doesn't deliver power right when you yank up on the collective like a piston powered machine. And flying out of trim, it feels like the ship is going to roll over.

But the biggest difference is tail rotor authority. The 206 doesn't have very much. The Army wrote the book on loss of tail rotor effectiveness back in the sixties when the phenomenon was discovered in the first generation of the 206. Hovering with a tailwind requires some serious Gregory Hines action on the pedals. And making slow right turns with a light breeze is ill-advised.

1 comment:

alaskapowder said...

I bet it's nice to have some more elbow space in the Bell 206. Add some pictures Captain.