Would this actually work

[ORegan]

During my random image browsing, I found this image and I'm now pondering the feasibility of such a contraption being used instead of our extremely long runways. Now, obviously there'd have to be a way for the treadmill to read and keep up with the constantly increasing speed of the aircraft, but other than that, would there be anything hindering such a system being built at ground level?

I know this isn't technically about giant robots and such, but it DOES seem like something they'd use

[OutLawSuit]

Fundamentally I don't see how it is much different than what happens on aircraft carriers. The limiting factor of it on the ground would simply be cost I believe.

[Talos]

Considering that lift is generated by AIR speed and not ground speed...it won't work. It doesn't matter how fast the wheels are spinning, if there's no air flowing past the wings fast enough, it won't take off no matter how hard you try.

Take aircraft carriers, for instance. The steam catapults on that push the plane forward at over 100 knots, enough to generate enough lift (usually) to take off. Carriers frequently will steam into the wind at about 30 knots just to generate more wind over the deck and gain additional lift for the planes. That's why this treadmill idea wouldn't work in the slightest, I'm afraid.

[Turinu]

Aye. They covered this in an episode of Mythbusters, and I believe the experiment failed / didn't meet expectations.

[Newtype87]

Aye. They covered this in an episode of Mythbusters, and I believe the experiment failed / didn't meet expectations.

Well, the plane did take off, both as a model and a full-sized plane, so I'd call it a success. Though the Myth was that it wouldn't take off, so it was busted in that sense.

[Wingnut]

But both planes took off under their own power. And the image in the OP I think implies that the treadmill could be used as a means of accelerating the aircraft as opposed to keeping it on the ground as per the myth investigated by Adam and Jamie.

As Talos said, it wouldn't be much different than launching from an aircraft carrier in practice.

[ORegan]

But both planes took off under their own power. And the image in the OP I think implies that the treadmill could be used as a means of accelerating the aircraft as opposed to keeping it on the ground as per the myth investigated by Adam and Jamie.

As Talos said, it wouldn't be much different than launching from an aircraft carrier in practice.

The image in the OP would also imply we build a treadmill large enough to fit a plane.

The description I gave after the image describes the same sort of situation you'd have if you went the opposite way on an escalator(or running on a treadmill in general). Think of a floor system similar to on the Jetsons, excepts keeping you in the same spot you're on, and through sensors etc is matching your speed precisely. Now apply that to an airplane. I'm not sure if the plane actually achieve flight from it or simply stay in place.

[Sleepneeded127]

it would be more effective to have the aircraft going in the same direction as the treads. this would increase airflow over the wings. being that treads move the aircraft froward at "X"mph and the aircraft moves itself at "Y"mph
giving you added speed, just like running up the escalator.

[scythedd7]

It would work since whether the ground is moving doesn't effect the airplane since it wheels would just spin faster, since planes don't use their wheels to accelerate, it would just move forward like normal. It would still require the same amount off runway though, as the ground would just kinda be a non-factor other then a normal force. The direction the treads are going don't have much effect, as the wheels are free spending and are only there for the normal force and allow for minimal friction. So yes it would take off, but it wouldn't be more efficient, since it would still need to the same amount of runway. The Mythbuster proved this works, as they did it in real life. They put a plane on a runway with a moving ground and it took off as normal. Again, since the wheels aren't used for power, the moving floor has no effect.

[Dynames]

Yea it will work, the Mythbusters did the same myth and proved that it can take off on a tread mill

[Izayuukan]

Yea it will work, the Mythbusters did the same myth and proved that it can take off on a tread mill

I take a lot of the bigger myth-busting attempts with a grain of salt, especially after that fiasco with the jet engine and the car. Now Top Gear, there's a show you can (mostly) trust.

[thanatos]

I take a lot of the bigger myth-busting attempts with a grain of salt, especially after that fiasco with the jet engine and the car. Now Top Gear, there's a show you can (mostly) trust.

Mythbusters did get this one right, though frankly the answer is so obvious that even someone like me who barely made it through grade 11 physics can understand it.
scythedd7 has it right. Airplane wheels are free-spinning (though they do have brakes) and do not conduct power to the runway. The only thing that makes a plane move is the engines, which is to say the air being forced, either by a jet or propellor, in the opposite direction as the plane moves. The only thing that can cause a plane to lift off the ground is air moving over its wings. To get the air moving over the wings, the plane must move forward.
Putting it on a treadmill simply means that the free-spinning wheels will turn faster than they would if it were on a normal runway.

A real question would be would this take off?
Answer: Yes if the turntable spins in the same direction as the rotors. No if the turntable went in the opposite direction at the same rpm of the rotors, then the rotos would simply remain in a fixed postion while the fuselage spins.

[Izayuukan]

The only thing that can cause a plane to lift off the ground is air moving over its wings. To get the air moving over the wings, the plane must move forward.

Which it isn't doing, since it is on a treadmill.

[Phoenix012]

I would also like further clarify some of the above arguments.

The airplane can not take off of the treadmill if the relative airspeed (speed of the plane going past the air, or the air going past the plane, same thing) is zero. In this case where the treadmill is pushing against the airplane, the wheels spin, but the airplane itself doesn't go anywhere, and therefore it doesn't take off. The airplane has to be moving against the air for it to fly, not the ground.

The airplane can take off of a treadmill if it pushes the airplane the same direction that it is facing and the treadmill is long enough (half as long as a normal runway). In this case it becomes like a moving walkway you use in airports. It simply brings the airplane to takeoff airspeed in a shorter distance. Of course you still need a pretty long stretch of space and it would be better to use a catapult, like on aircraft carriers, as a catapult provides additional acceleration (like making the engines more powerful) instead of just additional velocity (which increases your speed by a flat amount, like the walkways at the airport).

In conclusion, making a treadmill for airplanes is a complete and utter waste of time. If space for a runway is an issue, a catapult (as on aircraft carriers) or rocket booster (youtube C-130 rocket assisted takeoff) is your best bet.

I hope that further explained what others were trying to say. Maybe it just made things more confusing, but I tried.

[thanatos]

The only thing that can cause a plane to lift off the ground is air moving over its wings. To get the air moving over the wings, the plane must move forward.

Which it isn't doing, since it is on a treadmill.

No, the plane will move forward because the engine acts of the air around the plane and not the ground. The jet or propellor pushes air towards the back of the plane and (according to Newton's 3rd law - for every action there is an equal and opposite reaction) as a result, the plane moves forward relative to the air around it.

This is why planes can be outfitted with skis and take off from ice-covered runways: the undercarriage has nothing to do with moving the plane forward.

[scythedd7]

In conclusion, making a treadmill for airplanes is a complete and utter waste of time. If space for a runway is an issue, a catapult (as on aircraft carriers) or rocket booster (youtube C-130 rocket assisted takeoff) is your best bet.

I hope that further explained what others were trying to say. Maybe it just made things more confusing, but I tried.

I agree with this completely. The treadmill would really do nothing other then to confuse the heck outta everyone, and only provide problem (like it there was some sort of difficulty taking off. only a Catapult or a Rail driver or something to make it move faster relative to the air, more so then what the plane's engines could generate, would provide any meaningful results.

[Izayuukan]

No, the plane will move forward because the engine acts of the air around the plane and not the ground. The jet or propellor pushes air towards the back of the plane and (according to Newton's 3rd law - for every action there is an equal and opposite reaction) as a result, the plane moves forward relative to the air around it.

This is why planes can be outfitted with skis and take off from ice-covered runways: the undercarriage has nothing to do with moving the plane forward.

I'm not wondering about the undercarriage, I'm wondering how a plane's wings can generate lift when it is stationary to the the air around it.

I realise that the propeller or turbofans will push it forward relative to the ground, but not perfectly. Take a toy car (if you have one), place it on a piece of paper, then gentle pull the paper backwards relative to the car. The car will go backwards with the piece of paper. So taking off from a treadmill will require more power than on stationary ground, since the plane must overcome the treadmill's speed (assuming it is going "against the grain" as it were).

And, the plane will still need roughly the same amount of ground to take off, since it must build up speed relative to the air. It cannot do that on a treadmill as relatively short as the one depicted in the link in the opening post.

So yes, a plane can take off from a treadmill, but not vertically, which is the implication from (well, question asked by) that picture.

[crashlegacy14]

I would also like further clarify some of the above arguments.

The airplane can not take off of the treadmill if the relative airspeed (speed of the plane going past the air, or the air going past the plane, same thing) is zero. In this case where the treadmill is pushing against the airplane, the wheels spin, but the airplane itself doesn't go anywhere, and therefore it doesn't take off. The airplane has to be moving against the air for it to fly, not the ground.

The airplane can take off of a treadmill if it pushes the airplane the same direction that it is facing and the treadmill is long enough (half as long as a normal runway). In this case it becomes like a moving walkway you use in airports. It simply brings the airplane to takeoff airspeed in a shorter distance. Of course you still need a pretty long stretch of space and it would be better to use a catapult, like on aircraft carriers, as a catapult provides additional acceleration (like making the engines more powerful) instead of just additional velocity (which increases your speed by a flat amount, like the walkways at the airport).

In conclusion, making a treadmill for airplanes is a complete and utter waste of time. If space for a runway is an issue, a catapult (as on aircraft carriers) or rocket booster (youtube C-130 rocket assisted takeoff) is your best bet.

I hope that further explained what others were trying to say. Maybe it just made things more confusing, but I tried.

Nuff said guys. really.

[scythedd7]

again, the engines do not act on the ground, at all, they act on the air. So if you have the engines running, and the air is not moving but the ground is, it is a moot point. The engines will still pull it forward (because air does not move with the treadmill) at the same speed it always does. Even if said treadmill is going the opposite direction at the plane take off speed, it will still take off. The ground is entirely moot as the wheels are near frictionless. You talk about airspeed as if it engines would be pulling air through them, but doing nothing to the wings, but forget the air is not moving, so the engines still pull it forward at the same rate as always, and treadmill has no effect. It's been proven, and just crunching the numbers would also prove it.

All in all it might take a second or to for the wheels to break the static friction of its wheels in their carriages and after that they would be in the skys.

[Talos]

again, the engines do not act on the ground, at all, they act on the air. So if you have the engines running, and the air is not moving but the ground is, it is a moot point. The engines will still pull it forward (because air does not move with the treadmill) at the same speed it always does. Even if said treadmill is going the opposite direction at the plane take off speed, it will still take off. The ground is entirely moot as the wheels are near frictionless. You talk about airspeed as if it engines would be pulling air through them, but doing nothing to the wings, but forget the air is not moving, so the engines still pull it forward at the same rate as always, and treadmill has no effect. It's been proven, and just crunching the numbers would also prove it.

All in all it might take a second or to for the wheels to break the static friction of its wheels in their carriages and after that they would be in the skys.

If that were true, why do we bother with installing wings on planes at all? It's not the engines that make the plane fly, it's the airstream over the wings creating lift. After all, gliders can fly and they don't have air moving through engines.