Friday, February 01, 2008

But that wasn't the point...

You mean Mythbusters actually did the airplane-on-a-conveyor-belt thing?





Wait, the pilot didn't think it would fly? That's not very reassuring. Look, dude, the plane doesn't get its forward motion from the landing gear. The wheels don't drive the plane, OK? The propeller does. That's why they call it that. It propels the plane. The plane won't sit still just because it's sitting on a moving surface. I thought the Navy doped this out years ago before they spent so much money building aircraft carriers.

(While filming "Six Days, Seven Nights", Harrison Ford [who actually can fly a plane] had to explain this to the director, who wanted Ford to taxi around without starting the propeller. He's good but he's not that good. While you're at it, see about holding the tide back too. Let me know how that goes for you.)

The question I thought this was about, which I think probably still is a good question (and is probably what some people thought the stunt was actually about), is whether the propeller, all by itself, can move enough air over the wings to generate enough lift to fly the plane without actual forward motion. I'm reasonably sure the answer to that one is "heck, no", but wouldn't it be neat to be proven wrong?

4 comments:

McGehee said...

Until they did the small-scale on Jamie's treadmill, I was sure the plane wouldn't take off. It took seeing it happen to show me where I was going wrong.

Then again, I'm not a licensed pilot.

Anonymous said...

Yes, the answer is 'no.' But see this:

http://www.custerchannelwing.com/

RNB

Daniel said...

Okay, I'm amazed. I'll admit I don't understand much of the Channelwing material, but I'm astounded that there's enough wiggle room in modern physics for something that demonstrably works as advertised to be so controversial.

The universe is not only stranger than we imagine, it is stranger than we can imagine.

John C. said...

You COULD use a conveyor belt to accelerate an airplane, but you would first have to lock it to the the belt so the wheels (which are designed to reduce friction with the substrate, after all) will not simply roll in reverse, so it will match the speed of the belt before being released. On an aircraft carrier, the planes are traveling with the speed of the carrier before takeoff, partly because the speed imparted to them was imparted gradually, and because an airplane on an aircraft carrier spends most of its time tied down, so it won't inconveniently roll about. The catapults are because the 35 or more knots a carrier gives, plus the prevailing wind, is still not enough for most modern airplanes to fly.