If a Boeing 737 is put on a treadmill going 250mph, will the plane take off?

Question

The plane is moving at takeoff speed ( roughly 250mph) give or take while sitting on the treadmill. Will the plane take off?


**note - the wheels arent moving but as you know, there is no front wheel or rear wheel drive axle's like on a car, on an airplane.

update - think of those moving walkway things at the airport

Answer 1

Yes, it will take off just fine. The wheels on an aircraft are free spinning, so it doesn't matter if the treadmill is moving them or not. It's the airflow over the wings that matters for lift, and the jet engines will push the plane forward along the treadmill. A car needs friction with the road to move forward, a plane does not.

Edit: No Woody, you don't understand what's happening. The situation is in no way analogous to a car, or running on a treadmill. We move forward due to the friction between our feet and the ground. That is what provides the "thrust" for our forward motion. In an plane, the thrust is provided by the engines; the wheels don't spin under power, and they provide no aid to the plane's acceleration. If a plane needed the motion of its wheels to take off, then planes on skis and floats couldn't work.

Let's see if I can explain this so that it's clear. First, let's take the case of a norrmal takeoff. The plane starts at the end of the runway. The jet engines provide thrust, and the plane accelerates forward to 250mph (to use the question's numbers), while the wheels spin at 250 mph in the opposite direction. The plane will accelerate regardless of what the wheels are doing; the only thing that could slow things down is if the pilot applied the wheel brakes. Even then, the friction of the tires against the pavement would not be enough to significantly slow the plane. All that would happen would be that the tires would drag along the ground, leaving huge black streaks. Yes, the plane would probably skid off the runway due to the tire damage and uneven friction, but that's not part of the actual question anyway, so we're assuming here that the plane keeps a straight course.

Now, imagine the entire runway is a giant treadmill, moving backwards at 250 mph. Until the engines start, the plane would move backward at 250 mph, since there would be no countering force. Assume the plane starts somewhere in the middle, or even at the takeoff end, or that the treadmill is several miles long. Once the engines start providing thrust, the plane would slow its backward movement, stop, then move forward, accelerating to 250 mph. The only difference now is that the wheels are spinning at *500 mph*; the rest of the plane is unaffected by the motion of the treadmill. Assuming the wheels can take the stress, and the unequal load doesn't cause the plane to careen off our "runway", and for the purposes of this "thought experiment" we assume both conditions are true, the only impact on the plane's ability to take off is that it must overcome the small amount of friction in the wheels, so it would need slightly more thrust than when taking off from pavement.

Just think that if instead of having engines, the plane was tethered to the far end of the runway by a long steel cable. The plane would move backwards with the treadmill until it ran out of cable. Then it would stay in place, wheels spinning. If they then started to reel in the cable, the plane would move forward. In this case, the cable is providing the same "thrust" as the engines.

For the truly daring among you, you can simulate the conditions of my last example at home. You need a treadmill, a pair of rollerskates, and a length of strong rope. Attach the rope to the far wall, and get on the treadmill wearing the rollerskates. Start the treadmill, and you will move backwards until the rope gets taut. Make sure that it will become taut before you're thrown backwards off the treadmill! Now, start pulling yourself forward, and you will move forward. Increase the speed of the treadmill while the rope is taut, and you will not move backwards, and you will be able to keep moving forward by pulling on the rope. Your arms and the rope are providing the thrust; the rollerskate wheels are free spinning (make sure they're well oiled), and are therefore not providing motive force, and only a small pulling force, since they are not completely frictionless.

A final point is that the "giant treadmill" actually occurs to some degree for a plane with floats taking off against a strong current. If the current is with the wind, then the plane is being pushed backward by the current, but the power of the engines overcomes the current, and pushes it forward. The treadmill is simply moving faster than the water, but the situation is the same. Wheels, floats, it doesn't make a difference. They simply hold the plane up; they don't provide any motive power.

Answer 2

From the way you worded the question, I'm assuming you're talking about a hypothetical moving runway that the plane is on since the wheels are not moving. In other words, something like the moving walkways they have in airports where you can just stand and it will move you through the airport. If that's the case, then the plane should be able to take off after reaching a certain velocity if the engines are brought up to speed and the pilot adjusts his controls at the right time.

Answer 3

Firstly, the 737's takeoff speed is LESS THAN 150 mph.
Secondly, it's the plane's AIRSPEED that counts.
But, in the end --
1) If the treadmill is going INTO the wind at 250 mph, assuming no strong tailwinds or crosswinds; and
2) The plane's brakes are holding fast, with engines off; and
3) the pilot rotates the craft at normal rotation airspeed --
The craft will get airborne -- for a short distance before crashing back to Earth.
That can be an expensive experiment.

Answer 4

Some people honestly do not know what they are talking about. No it will not take off, even if such an experiment were possible.

Lift is generated when airflow is accelerated over the surface of a wing. If the wing itself is not moving relative to the air then there cannot be any lift generated!

Think about it, do you ever feel the wind against your face when running on a treadmill....???? No, didnt think so....

Answer 5

If it's on a treadmill (direction of movement of the treadmill is opposite that of travel - you run and get nowhere) then no it won't - there will be no airflow over the wings. If it's on a moving walkway (direction of movement the same as direction of travel - you stand still but move forward) then yes it will, but only until it leaves the walkway, then it no longer has forward movement through the air and will come back down again.

Answer 6

You mean an outside force pushing the aircraft extremely fast and will it takeoff? Sort of like a catapult on an aircraft carrier? If you get the aircraft moving fast enough, so that you have sufficient lift on the wings it will take to the air, but you will have to apply thrust after take off to keep it airborne.

Answer 7

As long as the aircraft is moving it will lift off, the wheels on the landing gear only facilitate it moving while on the ground. If the aircraft is stationary as Woody said there is no wind flow and therefore no lift, so you would need a huge fan to create a "wind" fast enough for the aircraft to lift off, but as soon as it rose above the "wind" from the fan it would stall and fall.

Answer 8

The plane would lift off the ground but once it comes off the walk way it would lose its source of forward momentum and would come down to the walk way again. In this case it would be functioning like a glider. Something outside of it would give it the momentum to generate lift with its wings.

Answer 9

Actually, the takeoff speed for a Boeing is around 190 MPH.

That being said, no, it won't take off. It needs loft under the wings.

Answer 10

Yes, if the wheels are free spinning. It will need a bit more power but it will eventually take off. This question has been debated for a very long time on the internet.