The question of the month appears to be this. If you put an airplane on a treadmill and get it going really fast (working up a heck of a sweat, mind you), will it eventually take off?
Upgrade: Travel Better points out that David Pogue of the New York Times even picked this one up a few days ago (and that’s where this picture came from, though the headband addition was mine). So what’s the answer?
No, it won’t.
Now I’m amazed at how many conflicting opinions there are on this thing, because it seems very basic to me. Let’s say you get that treadmill humming in a really big gym (with no wind around) and the plane has full takeoff power going. Those wheels are racing on the treadmill, but it doesn’t matter what the wheels do here. Aircraft get lift from air passing over the wings, and in this case, there isn’t any.
If there’s no wind in the area and the plane isn’t moving through the air, then there will be no air passing over the wings. It’s that simple. Now if there happens to be a 200 knot headwind, you’re going to get airborne whether your engines are on or not, but I’m assuming that’s not part of the question here.
Ever wondered why airplanes take off on different runways at different times? Well, they always want to take off into the wind. The reason for that is once again that ground speed doesn’t matter – it’s airspeed that does.
For simplicity’s sake, let’s say you need 100 knots of airspeed to get off the ground (meaning the air is moving over your wings at 100 knots). If the wind is blowing 10 knots down the runway and you take off into it, you only need to be going 90 knots on the ground, because 90 knots plus the 10 knots that the air is already moving will get you where to need to be.
Conversely if you took off the other way, you would need to be going 110 knots because you’ve already got 10 knots at your back. Only when you get to 110 knots on the ground would you have 100 knots of airspeed.
On that treadmill, air is not moving over the wing at all so it’s not taking off.