It takes off

We watched the Myth­busters tack­le the “Air­plane on a Con­vey­or Belt” issue last night. They did not real­ly build a huge con­vey­or belt (they essen­tial­ly used a long can­vas tarp to pull the run­way out from under the plane), and so the result (the air­plane took off) won’t real­ly sat­is­fy every­one. But, it remains the right answer.

Here’s some back­ground: the kot­tke post that start­ed it all, the expla­na­tion for the sci­en­tif­i­cal­ly mind­ed (the com­ments are fun), and kot­tke’s live­blog­ging of the Myth­busters episode.

Here’s how I try to explain it. An air­plane fly­ing through the air is vir­tu­al­ly no dif­fer­ent than one “fly­ing” on the ground. The one on the ground is not (yet) going as fast as the one in the air, and there’s a minis­cule amount of fric­tion act­ing on the bear­ings in the plane’s wheels, but real­ly, they are mov­ing under the same laws of physics. Air­plane push­es on the air, and moves for­ward. What the ground, or the con­vey­or belt are doing to the wheels is large­ly irrel­e­vant. No mat­ter how fast the con­vey­or belt goes, all it is act­ing on are the wheels of the air­plane, not the plane itself. It can make those wheels spin crazy fast, but the plane will still take off.

So there.

Oh, and I like the sen­ti­ment of kot­tke’s t‑shirt, but I’d like a pic­ture of a plane on it, frankly. And a con­vey­or belt.

Published by

Danny

My name is Danny, and I grew up living overseas, but have settled in Kansas, where it turns out some of my family started, back when. I am helping to raise my own family, and hoping to be proud of what I've done when it's all over.