A jet plane on a large treadmill

[stuckathuntermtn]

How is this still a thing?

[Svengali]

so can the 747 land on the treadmill? or will it end up switch across the road?

[shroom]

asking the real questions

[stuckathuntermtn]

It would wind up switch, across the road, in a fireball. Sudden deceleration tends to not be pleasant.

[old goat]

Check out high bypass turbofans.

I see- a high bypass turbo fan is more like a prop plane--the thrust is mostly provided by air being pushed backwards, as with a propeller--than like a rocket. Thanks.

[Tippster]

Either way they are completely independent of what's going on at the wheels.

[wyeaster]

if you put one side of wheels on a treadmill going forward and the other side of wheels on a treadmill going in reverse, will the jet start to spin and take off like a helicopter?

[stuckathuntermtn]

Either way they are completely independent of what's going on at the wheels.

Not on the ground

How is this still a thing?

[stuckathuntermtn]

If they were completely independent of each of each other, there wouldn't be planes that use skis or floats.

[ill-advised strategy]

Fair enough, but in the special cases of the questions asked here there is specific information in each that defines which of those assumptions to use. That's the source of confusion once you get right down to it.

we should probably avoid getting right down to it.

[ill-advised strategy]

1) this is like that argument in Good Will Hunting, except it's between 13 identical copies of this fucking guy:


2) this is what's going on in my brain as I read this:


3) "ooohhhhh rrrrrr please crash, please crash, please crash, please crash, please crash.... a;sdkfja;dsklfjads;kjfd"


4) Nevermind, got it all figured out

[Svengali]

Float planes in Alaska regularly land on rivers; thats sorta like a treadmill
Edit/add : and take off!

[2stix]

Treadmill doesn't spin if wheels don't spin.

You would think so. But if the treadmill is to match the wheel spin, then the treadmill would have to
Move in a forward direction to match the none moving wells. Therefore matching the wheel speed as per the directive, still profit?

[jono]

You would think so. But if the treadmill is to match the wheel spin, then the treadmill would have to
Move in a forward direction to match the none moving wells. Therefore matching the wheel speed as per the directive, still profit?

Heh. Put plane on blocks, spin wheels backwards until the treadmill gets the plane up to stall speed, profit?

[old goat]

Airplanes don't have power to the wheels, just brakes. If you put an unpowered airplane on a treadmill the wheels will spin at whatever speed the treadmill is going, as long as the brakes are released. The airplane won't move. If the airplane then starts its engines it will move forward along the treadmill, regardess of how fast the treadmill is going and will take off if the treadmill is long enough. If the wheels are on different treadmills--one going forward and the other back--if the plane is not powered it will turn 90 degrees until each wheel is on each treadmill at which point the tires will lay rubber on the treadmills or the treadmills will burn out.
Now what if the treadmill and the airplane are in an elevator?

[ill-advised strategy]

can a type 1 air tanker take off on a treadmill with an olympic swimming pool of dicks to then drop on anybody who thought it wouldn't take off?

[ill-advised strategy]

Folks, I can't emphasize this part enough:

[jono]

Airplanes don't have power to the wheels, just brakes.

I wasn't suggested powering the wheels, I meant that if your plane was on a treadmill that was stupid powerful and committed to turning at -wheel speed at all times (not the OP version, the one on page 31), then you could put the plane on blocks, wrap a long rope around each axle, and tie the ropes to an anchor somewhere behind the plane but off the treadmill. (Make sure you wrap under going forward and come back over the top.) Then some crewmen just walk over and start turning each wheel backward by hand. Once the treadmill starts to move they probably walk out in front or something to get out of the way.

Ill-advised-strategy can lend some rope?

Note to Aaron: this might be a troll. Course it might work, too; does that matter?

[Flyoverland Captive]

Why are we assuming that the treadmill can't move forward? If the wheels never move, thereby never making the treadmill move backwards, the plane never moves. But it's clear that the engines will make the plane move forward. Thus the paradox.
If the wheels can't spin, thereby making the treadmill spin, can't the planes engine thrust force the plane forward, making the locked wheels drag the treadmill forward? And at a certain speed, can't the plane lift off?

[stuckathuntermtn]

Float planes in Alaska regularly land on rivers; thats sorta like a treadmill
Edit/add : and take off!

And they have to go faster than the "treadmill" to take off.

[Svengali]

Float flying: River currents are an issue while taxiing for a variety of reasons. Wind direction/speed are much bigger factors regarding successful takeoff / landing

[GeezerSteve]

If the wheels can't spin, thereby making the treadmill spin. . . .

The original hypothetical assumes a self-powered treadmill.

[jono]

...can't the planes engine thrust force the plane forward, making the locked wheels drag the treadmill forward?

No, it turns out the tires are too sticky to let the engines just slide them because the plane weighs more than twice as much as the force of the engines.

[old goat]

The original hypothetical assumes a self-powered treadmill.

OMG--read it again. The original post talks about a treadmill that has a control system that adjusts its speed to the speed of the plane, implying that it is powered. Have you been laboring under that misunderstanding the whole time? That is so sad. Eleven yeas of your life wasted.

[MagnificentUnicorn]

No, it turns out the tires are too sticky to let the engines just slide them because the plane weighs more than twice as much as the force of the engines.

Not that his idea is workable but he's not talking about the wheels sliding he's talking about the wheels staying stationary and pulling the treadmill forward with the engine thrust. Again, reading fail or troll?