Jan 31
Psuedo-science: Planes on a treadmill
from kottke:
Here’s the original problem essentially as it was posed to us: “A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?”
What do you think? It’s a tough question, especially because of how it is worded.
I read this a few months back and at first I got it wrong, along with a slew of other people, including professional and amature pilots alike. This question became so popular that Mythbusters picked it up and (after a few delays) just aired an episode dedicated to this question. I missed the episode, but the event was liveblogged by Jason Kottke fantastically. Don’t read the post until you’ve spent some time thinking about the problem. Talk it out with a friend. The debate will surprise you. Before you read up on the outcome of the Mythbusters’ experiment, take a look at the original post linked at the top of the page and sift through the comments for a while. It is really interesting to see the different theories.
One of the best parts about this, I think, is that even though the Mythbusters have “proven” how the plane may or may not take off, there is still HUGE debate about it on the Mythbusters forums.
On a semi-related note, do you think it is as ridiculous as I do that someone liveblogged a TV show that almost everyone has access to? I understand that it was for his own amusement, but this just shows how much blogging has changed since its inception.
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January 31st, 2008 at 8:02 pm
That’s an interesting question. Before I read the comments and change my opinion, here’s my thoughts:
So basically, what gives a plane lift is how its wings cut through the air. The wings are tilted such that as they move forward in the air, it pushes the air down, and thus creates an equal force upwards. You see the opposite when a plane goes to land– the wings tilt up to push the air up and itself down, thus putting more pressure on the wheels to allow it to stop.
The moral, then, is that the plane needs some wind in its face to fly. Normally it creates it’s own wind by jetting forward. But if there’s no forward motion, then there’s no cutting the air, no equal and opposite force, and thus no flight.
Now, let’s see if I’m right.
February 11th, 2008 at 10:41 pm
I thought the EXACT same thing when I heard about this myth, and was throughly surprised when i figured out the answer!