Sequel to SOAP: Plane on a treadmill... will it fly?

[SteveB]

Ok, we got a mechanical engineer's perspective, now for a physics major to add his insight (which is the same as the M.E.'s): won't work, provided the treadmill is counteracting the forward motion of the plane (aka the plane doesn't appear to be moving relative to an observer on the ground). As mentioned above, the plane needs lift, which is proportional to the velocity of the plane relative to the air. The only way the plane could move is if this was during a hurricane, where the winds would be fast enough to generate the required lift...in which case we probably have bigger concerns than this. End of discussion.

The only assumption I made, was that the wheels of the plane provide an unlimited amount of friction...hey, I'm a physics major after all. Realistically, the jets would most likely overcome the limitation of the wheels, and the plane would start moving forward relative to the above-mentioned observer's frame of reference. I mentioned this above, but wanted to clarify.

Well, since jet airplanes over come their wheel's friction everytime they take off, i'd say it's a pretty safe assumption.

I think you need to explain how exactly the treadmill is going to overcome the thrust of the engines to stop the plane from moving forward, unless the treadmill is somehow also attached to the air mass that the plane is in.

BTW, every time I see either "End of Discussion" or "nuff said"...well, you get the picture.

[cjv998]

I think you need to explain how exactly the treadmill is going to overcome the thrust of the engines to stop the plane from moving forward, unless the treadmill is somehow also attached to the air mass that the plane is in.

Yep, and that's the glaring point that I overlooked the first time. As obvious and stupid as it sounds, the treadmill (presumably) doesn't speed up when the jet engines are fired up. When the jets are on, the plane has an additional forward force that the treadmill doesn't counteract, so the plane moves forward as it normally would (I think), and takes off as usual.

I think the conditions of the problem need to be more specific, though. As I said, I'm unsure if the treadmill is at a constant speed, or is set to keep the plane stationary, in which case my initial statement I deleted would be true.

And slightly off-topic, but I don't think the planes' wheels overcome friction (opposing the direction of travel) when the plane is moving...if that were the case, the wheels would slide/drag across the ground. Instead, the friction between the wheel and ground is what keeps them spinning, because that's greater than the friction that's between the wheel and the bearing. Once again, I'm not sure about this, but it sounds correct at the moment.

[deevergote]

The friction of the wheels wouldn't stop the plane... but the wheels could potentially fail, or cause the plane to require more room to get up to speed. Most likely, if the friction is enough to slow the plane down, the bearings are about to give up anyway.

I dont understand how the plane could take off...its sitting still...the wheels are the only thing moving.

Did you not read the rest of the thread? Or do you just not get it? The speed and direction of the wheels have nothing to do with the plane as it moves through the air.

Put on some rollerskates. Get on a treadmill. Hold yourself in place. You won't move, but the wheels will turn. Now pull yourself forward. You'll move forward. the wheels will be spinning fast... the speed of the treadmill plus the speed of your forward movement... but you'll feel absolutely no resistance from the treadmill. Same principle.

[ACC0RD22]

Put on some rollerskates. Get on a treadmill. Hold yourself in place. You won't move, but the wheels will turn. Now pull yourself forward. You'll move forward. the wheels will be spinning fast... the speed of the treadmill plus the speed of your forward movement... but you'll feel absolutely no resistance from the treadmill. Same principle.

basically. As a ME major, I say it takes off.

also,

http://www.cb7tuner.com/vbb/showthread.php?t=54339

[owequitit]

[owequitit]

A Boeing 777 has enough power to fly around FULLY LOADED (that is about 750,000lbs in case you were wondering) ON ONE ENGINE!

The bearings are not going to stop it. Worst case scenario, the wheels are spinning at 300MPH. An emergency, no flap landing at maximum landing weight (closer to 500,000 lbs) would be near that speed with no real stress on the bearings.

The airplane is going to fly. I hope mythbusters will do it so that the goddamn threads will die already.

Wheels have nothing to do with how an airplane flies. I can put it on floats, skids, or leopard skin boas. As long as it has enough thrust to push itself forward, it is going to accelerate and fly.

I can fly a plane with 0 wheels.

I can fly a plane with 0 groundspeed.

I can fly a plane in a tunnel

I can fly a plane in a train

I can fly a plane Sam I Am.

[gloryaccordy]

LOL Scott is the best

[TypeG]

WOW, people really do have a hard time with this huh? later.

[deevergote]

If the wheels spin too fast for the bearings to withstand the stress, the wheels will fail, and the plane will crash. It will not fly.

If the treadmill is only as long as the plane, the plane will roll off the treadmill, not fly off.

If the treadmill is raised and as long as the plane, the plane will fall off, crash, and will not fly.





In theory, it will fly. Take other unknown factors into consideration, it might not

[ACC0RD22]

If the wheels spin too fast for the bearings to withstand the stress, the wheels will fail, and the plane will crash. It will not fly.

If the treadmill is only as long as the plane, the plane will roll off the treadmill, not fly off.

If the treadmill is raised and as long as the plane, the plane will fall off, crash, and will not fly.





In theory, it will fly. Take other unknown factors into consideration, it might not

Well, all those are special cases that would make sure the plane wouldnt fly if the treadmill was replaced by a runway, and thats unfair!

[accordaffair]

Same question as last time, same answer

I think someone is having trouble realizing the answer

I will use my magic to make the plane float an inch above the ground, it will move forward, the treadmill is


nm, plz close thread before I have an aneurysm, hehe

[owequitit]

If the wheels spin too fast for the bearings to withstand the stress, the wheels will fail, and the plane will crash. It will not fly.

If the treadmill is only as long as the plane, the plane will roll off the treadmill, not fly off.

If the treadmill is raised and as long as the plane, the plane will fall off, crash, and will not fly.





In theory, it will fly. Take other unknown factors into consideration, it might not

If I call God and have him kick in a large enough direct headwind, it will not matter what the conditions of the treadmill are and the plane WILL fly.

[deevergote]

If I call Godzilla and he rips the wings off the plane, it wouldn't fly!

[owequitit]

If I call Godzilla and he rips the wings off the plane, it wouldn't fly!

Yes, but if I called the Japanese Self Defense Force and had them intercept Godzilla, they could potentially stop him.

And if that didn't work, there is a good chance that he would trip, fall and knock his ass out on the big huge giant moving treadmill that the plane is taking off on. With the big huge headwind.

Plus, while Godzilly might be big enough to rip the wings off of a 777, he probably wouldn't do too well when 3/4 of a million pounds crashes into his ass going 200MPH. That is a lot of hurt put down right there!

[ACC0RD22]