If an AIRPLANE is on a TREADMILL will it take off? (Physics)

[IPoopStandingUp]

Treadmills match your speed? I always thought you set a speed and had to keep that pace or fall off.

No cardio crew

[NoobGains23]

Treadmill's can have motors to match desired speeds.

Hypothetical treadmill is using such a feature, and matching the speed of the plane.

This is all confusion based on what type of treadmill is being used.

Basically this.

If treadmill has a max speed of 100mph. Planes jet engines can create a rolling ground speed of 550mph, plane will take off at whatever manufacturers minimal take off speed was tested at (say 200mph). So plane would need to reach 300mph (on the treadmill) before it lifts off, or 200mph on a normal runway.

[NoobGains23]

Well, what if you put your hand behind the toy car and put 0 force on it, besides the very little it takes to keep it in place due to friction.

The treadmill could be going 1mph or 1000 mph and it takes the exact same minimal force to keep it in place. This is why if you put actual force behind it (a jet engine) it will just move forward. Actually, while the treadmill is rocketing from 1-1000, you can still just move the toy car back and forth with your hands, as easily as if it was on the ground.


people keep assuming the treadmill can go fast enough to keep the plane in place, when that's not physically possible. It will always move forward just like it wasn't on the treadmill at all.

Only if the treadmill remains at that speed. Otherwise no.

[32vape]

Damn people. The wheels do not drive the plane forward the thrust coming out the back of the engines do. The tires or bearings in the landing gear would fail before there would be enough friction from wheel speed to hold the plane back.

[Trojans86]

A treadmill is going to match a speed of a wheel that is based on the speed of the treadmill? Nice try brah. The airplane's wheel speed is faster than the treadmill (lets say 1mph). Try to set your treadmill speed to 1 mph faster than the speed of itself.

[_Muskelberg_]

So I get that an airplane doesnt move forward with its wheels. So it will take off, because it just doesn't matter what the wheels are doing.

BUT.... what ARE the wheels actually doing while it takes off?

[NoobGains23]

The pilot applies the breaks, the pilot goes full throttle, the thrust overcomes the friction of the wheels on the treadmill, the wheels skid along the treadmill without rotating, the plane reaches 180mph and flies off into the distance, luckily there was a fresh set of tyres on the plane

Only if the treadmill doesn't match the rolling ground speed created by the thrust of the engines. Otherwise no

[AdamOm]

Treadmills match your speed? I always thought you set a speed and had to keep that pace or fall off.

No cardio crew

THIS

If the plane does manage to go faster than the belt, it will fall tip first over the top of the treadmil, and the plane will get stuck.

[LaCosaNostra90]

wow theres some dumb people out there.


the plane would take off.


end of story.

[Trojans86]

So I get that an airplane doesnt move forward with its wheels. So it will take off, because it just doesn't matter what the wheels are doing.

BUT.... what ARE the wheels actually doing while it takes off?

making it easier for the plane to move forward. If it didnt have wheels it would drag across the ground which would create a helluva lot more friction.

[bangwhosnext]

Basically this.

If treadmill has a max speed of 100mph. Planes jet engines can create a rolling ground speed of 550mph, plane will take off at whatever manufacturers minimal take off speed was tested at (say 200mph). So plane would need to reach 300mph (on the treadmill) before it lifts off, or 200mph on a normal runway.

It wouldn't matter if the treadmill reached 300mph... The plane will only take off when its airspeed is enough to create lift across its wings. If the plane is stationary, the plane will obviously experience zero aerodynamic lift... All the "treadmill" has done is make the wheels turn faster.

[32vape]

Basically this.

If treadmill has a max speed of 100mph. Planes jet engines can create a rolling ground speed of 550mph, plane will take off at whatever manufacturers minimal take off speed was tested at (say 200mph). So plane would need to reach 300mph (on the treadmill) before it lifts off, or 200mph on a normal runway.

Ground speed does not matter for lift. Airspeed does. If the treadmill is going 100 mph and the plane was just sitting on it not moving forward or back, the airspeed is 0. Yes the wheels are spinning at 100 mph, but just the wheels not the plane.

[NoobGains23]

making it easier for the plane to move forward. If it didnt have wheels it would drag across the ground which would create a helluva lot more friction.

Try dis on 4 size:

1 mile wide treadmill
Powered by huge motor
A car drives on the treadmill
Car reaches 140mph
Treadmill is also moving at 140mph
Car thinks he gon' troll, it has 10 jet engines on the roof of the car in a huge wing formation
Car brah powers all 10 jet engines to full thrust
Combined thrust makes car reach 1000mph
Huge treadmill matches 1000mph instantly
Car stays stationary to observer looking on from a distance

Who was airflow?

[_Muskelberg_]

making it easier for the plane to move forward. If it didnt have wheels it would drag across the ground which would create a helluva lot more friction.

I get that.

But a plane which is taking off actually has spinning wheels, yes? So the wheels move. And the treadmill moves as well.

So whats going to happen? The plane basically just thrusts forward.... wheels spinning faster and faster till take off?

[MrGreenz]

Only if the treadmill doesn't match the rolling ground speed created by the thrust of the engines. Otherwise no

what is matched? wheel speed or plane speed?

[jaygee15]

well what say you misc?

you are a special kind of stupid

[NoobGains23]

what is matched? wheel speed or plane speed?

We are talking about airplanes, which rely on rolling ground speed to create enough airflow under the wings to produce lift. If the specific plane was tested and concluded that it needed 200mph rolling ground speed to lift off as a minimum, that is what it needs.

That said, if 200mph worth of wind was created via a huge fan, the plane would lift off from stationary. Treadmill cant produce that though

[socrates07]

this is one hilarious thread

[ironicinori]

Still haven't heard an answer to this:

1. You're holding a toy car in place on a treadmill
2. Treadmill's speed increases from 1mph to 1000mph
3. You can still move the toy car back and forth with your forearms.
4. It's not harder to hold it in place the faster it goes.
5. You could easily push it forward until it is not on the treadmill anymore i.e. liftoff.


inb4 "it would accelerate to keep up with you"

In the "infinite accelleration" scenario, the wheels AND the treadmill would accelerate so instantaneously that they'd both blow up, so we have to ignore friction in the treadmill and the wheels.

[DancerInTheDark]

The treadmill could be going 1mph or 1000 mph and it takes the exact same minimal force to keep it in place. This is why if you put actual force behind it (a jet engine) it will just move forward. Actually, while the treadmill is rocketing from 1-1000, you can still just move the toy car back and forth with your hands, as easily as if it was on the ground.

Mmm... No ? Rolling resistance DOES increase with speed AFAIK. Surely it is extremely low at typical treadmill velocities but the treadmill of the thought experiment is imaginary anyway.

I would also add that the thrust "going through the wheels" or "coming from the jets" is a completely irrelevant point, as the average force balance of the problem has to be balanced (and it is) wherever the thrust is applied. A car would not power through simply because of the fact that the trasmission imposes a fixed/finite wheel/engine turn ratio, not because the power "goes through the wheels", and on the same note plane with skis rather than wheels would quite clearly NOT take off.

[pieceofdebri79]

So there's literally no way to make a treadmill that'll keep a jet engine stationary? I keep going back and forth between who I believe.

[MrGreenz]

We are talking about airplanes, which rely on rolling ground speed to create enough airflow under the wings to produce lift. If the specific plane was tested and concluded that it needed 200mph rolling ground speed to lift off as a minimum, that is what it needs.

That said, if 200mph worth of wind was created via a huge fan, the plane would lift off from stationary. Treadmill cant produce that though

You just contradicted yourself

GG

[LaCosaNostra90]

Mmm... No ? Rolling resistance DOES increase with speed AFAIK. Surely it is extremely low at typical treadmill velocities but the treadmill of the thought experiment is imaginary anyway.

I would also add that the thrust "going through the wheels" or "coming from the jets" is a completely irrelevant point, as the average force balance of the problem has to be balanced (and it is) wherever the thrust is applied. A car would not power through simply because of the fact that the trasmission imposes a fixed/finite wheel/engine turn ratio, not because the power "goes through the wheels", and on the same note plane with skis rather than wheels would quite clearly NOT take off.

You are a special kind of stupid

[Kavliari]

Assuming the treadmill has a maximum speed (which all do) then yes the plane will take off.
The planes jet engines will create more thrust than the treadmill can create backwards speed, as a result the thrust will be more than the reverse roll caused by the treadmill. The plane will struggle but will eventually take off by going forwards faster than the treadmill can pull it backwards

It wont lift from the treadmill though, there's no air moving around the wings to generate lift, the aircraft will just fall off the end of the treadmill.

[NoobGains23]

Still haven't heard an answer to this:

1. You're holding a toy car in place on a treadmill
2. Treadmill's speed increases from 1mph to 1000mph
3. You can still move the toy car back and forth with your forearms.
4. It's not harder to hold it in place the faster it goes.
5. You could easily push it forward until it is not on the treadmill anymore i.e. liftoff.


inb4 "it would accelerate to keep up with you"

In the "infinite accelleration" scenario, the wheels AND the treadmill would accelerate so instantaneously that they'd both blow up, so we have to ignore friction in the treadmill and the wheels.

4. Doesn't make sense so question invalid. Car would be harder to hold in place at 500mph than it would at 1mph

[pieceofdebri79]

Still haven't heard an answer to this:

1. You're holding a toy car in place on a treadmill
2. Treadmill's speed increases from 1mph to 1000mph
3. You can still move the toy car back and forth with your forearms.
4. It's not harder to hold it in place the faster it goes.
5. You could easily push it forward until it is not on the treadmill anymore i.e. liftoff.


inb4 "it would accelerate to keep up with you"

In the "infinite accelleration" scenario, the wheels AND the treadmill would accelerate so instantaneously that they'd both blow up, so we have to ignore friction in the treadmill and the wheels.

Okay, that makes sense. Repped

[Brozef]

ENOUGH air needs to be passing over the wings (airfoil). And no the prop doesn't do this.

Not that complicated.

[_Muskelberg_]

Still haven't heard an answer to this:

1. You're holding a toy car in place on a treadmill
2. Treadmill's speed increases from 1mph to 1000mph
3. You can still move the toy car back and forth with your forearms.
4. It's not harder to hold it in place the faster it goes.
5. You could easily push it forward until it is not on the treadmill anymore i.e. liftoff.


inb4 "it would accelerate to keep up with you"

In the "infinite accelleration" scenario, the wheels AND the treadmill would accelerate so instantaneously that they'd both blow up, so we have to ignore friction in the treadmill and the wheels.

This actually makes it easier to understand.

I couldn't give a fukk how fast the treadmill and the wheels are spinning. I still can push the toy plane around.

But I still wonder what would actually happen to the wheels and the treadmill..... will they keep accelerating untill the plane finally lifts off?

[DancerInTheDark]

You are a special kind of stupid

Mmm... No ? Problem formulated trying to trick people into stating airplanes power through wheels and then failing to impose any relevant physical constraint is a special kind of stupid.

[MrGreenz]

So there's literally no way to make a treadmill that'll keep a jet engine stationary? I keep going back and forth between who I believe.

No

Hypothetically if a treadmill was created that could generate huge speeds, then the plane wheels would blow out before the plane took off.

But in a physics problem sense, no.