Randazzo

So, you have a plane on a conveyor belt...

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1 hour ago, cubinator said:

But if the wheels are not exerting any force on the car,

Yes they are, otherwise cars couldn't move.

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12 hours ago, sevenperforce said:

If a Boeing 747 goes to full throttle and then applies the brakes, it will not take off. A 747's TWR is around 0.3; the coefficient of sliding friction between rubber tires and asphalt is around 0.8.

But if said 747 is on ice....

18 hours ago, Gargamel said:

Meanwhile:

392602eb42d4433d8ea29607f66c902e

 

 

More like:

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14 minutes ago, DAL59 said:

Yes they are, otherwise cars couldn't move.

Not if the car is in neutral and the wheels are acting as rollers.

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Could you guys take a break from the arguing to state the problem for me? I want to be sure I understand the parameters here.

Are we talking about a normal physically-possible airplane? Or something really unusual with frictionless parts, infinite thrust, vectoring jet nozzles, anti-gravity drive, or any other magic somebody would care to invoke?

And for the conveyer belt, are we talking about something that could actually be engineered with a reasonable acceleration and top speed, or are we are we allowed to invoke unphysical speeds and accelerations, or other magic?

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And which wheels are we using. Nose gear wheels are usually smaller than the main wheels so will have a greater RPM than the main wheels for any given speed along the runway. Does the conveyor belt have the same diameter rollers as the wheels? Are we matching RPM or the linear speed of the wheel axle?

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12 hours ago, p1t1o said:

What if its a tank, which has pre-installed wheel-speed-matching conveyors on both sides?

On a conveyor.

Going uphill.

Underwater.

At the North Pole.

I know this one. You don't bury survivors.

7 minutes ago, Brotoro said:

Could you guys take a break from the arguing to state the problem for me? I want to be sure I understand the parameters here.

I'm sorry, but the question is specifically stated to avoid you understanding the parameters.

7 minutes ago, Brotoro said:

Are we talking about a normal physically-possible airplane? Or something really unusual with frictionless parts, infinite thrust, vectoring jet nozzles, anti-gravity drive, or any other magic somebody would care to invoke?

Yes.

7 minutes ago, Brotoro said:

And for the conveyer belt, are we talking about something that could actually be engineered with a reasonable acceleration and top speed, or are we are we allowed to invoke unphysical speeds and accelerations, or other magic?

Yes.

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3 hours ago, cubinator said:

But if the wheels are not exerting any force on the car, they can spin in place.

 And it doesn't matter then whatever is the movement direction of the belt / tread and the car movement.

Then they add jet engines and takeoff.

 

One question so far I want to ask to those who insist the plane can't takeoff :

Spoiler

20180516_144812.png

Wproj is the projection of W (weight) vector in horizontal direction. What's the value ?

 

Edited by YNM

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If a plane is on a treadmill, is it still able to spray chemtrails?

 

More importantly:

If Paul McCartney was killed trying to take off in a plane on a treadmill and replaced with a reptilian clone, how was there enough jet fuel left to melt the fake pictures of the Apollo program on the holographic moon of the flat, but hollow, earth?  Checkmate, aliens!

 

Edit:
I would like to sincerely apologize to the Illuminati for leaving them out of this post, as they are truly responsible for everything.  Fnord!

Edited by razark

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We should move this to the Kinda Science & Maybe Flight sub forum....

God this thread is great.  Hilarious.   And joyfully civil. 

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37 minutes ago, Gargamel said:

We should move this to the Kinda Science & Maybe Flight sub forum....

You seem to have mistyped "/dev/null".

:wink:

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9 hours ago, DAL59 said:

In order for the car to move, the wheels must spin.  The treadmill forces the wheels to not spin in the correct direction.  The winch is irrelevant.   Which way is the correct direction? Doesn't matter. 

Which way the wheels spin is irrelevant. The winch can tow the car sideways if it wants to. The wheels won't enjoy that, but they don't get a say in the matter.

With both the winch and the plane the motive power available far outweighs any conceivable resistance of road, runway or treadmill. And the whole point of freely spinning wheels is that they are resistance reducers. 

Neither the towed car nor the plane need to push against the runway to move. One can pull on a winch and the other can push on the air. Again, the road is irrelevant.

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5 hours ago, Gargamel said:

We should move this to the Kinda Science & Maybe Flight sub forum....

God this thread is great.  Hilarious.   And joyfully civil. 

I love the fact that despite there being a video a few pages back of an airplane actually taking off from a treadmill, we can still argue for either side almost indefinitely.

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7 hours ago, cubinator said:

being a video a few pages back of an airplane actually taking off from a treadmill

It wasn't even close to an ideal treadmill though.  The treadmill has to be frictionless with its treadmill motors, or automatically increase in speed.

7 hours ago, cubinator said:

almost indefinitely

ftfy

Edited by DAL59

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6 minutes ago, DAL59 said:

It wasn't even close to an ideal treadmill though.  The treadmill has to be frictionless with its treadmill motors, or automatically increase in speed.

 

It was increasing in speed. 

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1 hour ago, DAL59 said:

It wasn't even close to an ideal treadmill though.  The treadmill has to be frictionless with its treadmill motors, or automatically increase in speed.

No matter how much the treadmill accelerates, it will not be able to prevent the plane from moving.

Here's the experiment. Stand on a treadmill while wearing roller skates. Turn on the treadmill and use the grips to hold yourself in place, so that you are stationary while the treadmill rolls underneath you and your wheels spin.

Test this at varying speeds. Does the speed of the treadmill affect how hard it is to pull yourself forward?

 

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Haha, this is great and a classic case of misdirection...Let's get down to the basics - normal planes take off because enough air is passing fast enough around the wings to cause lift to exceed the plane's weight. What the plane is sitting on doesn't matter. How the plane achieves take off speed doesn't really matter either. What matters is the speed of the air passing the wings.

Engines accelerate the plane forwards. The conveyor belt is trying to accelerate the plane backwards. How much backwards acceleration would be determined mostly by how frictionless the wheels are. If they are totally frictionless and the plane is pointed exactly in line with the belt, then the belt can go backwards as fast as it wants and the plane will sit there with the wheels spinning furiously. Real wheels will have some rolling friction so the plane will be pulled backwards. As long as the engines are powerful enough to overcome the backwards force and accelerate the plane to takeoff speed, it'll take off. :)

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1 hour ago, Tyko said:

Haha, this is great and a classic case of misdirection...Let's get down to the basics - normal planes take off because enough air is passing fast enough around the wings to cause lift to exceed the plane's weight. What the plane is sitting on doesn't matter. How the plane achieves take off speed doesn't really matter either. What matters is the speed of the air passing the wings.

Engines accelerate the plane forwards. The conveyor belt is trying to accelerate the plane backwards. How much backwards acceleration would be determined mostly by how frictionless the wheels are. If they are totally frictionless and the plane is pointed exactly in line with the belt, then the belt can go backwards as fast as it wants and the plane will sit there with the wheels spinning furiously. Real wheels will have some rolling friction so the plane will be pulled backwards. As long as the engines are powerful enough to overcome the backwards force and accelerate the plane to takeoff speed, it'll take off. :)

If the conveyor belt pushes the plane forward, will the wheels spin?

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6 minutes ago, sevenperforce said:

If the conveyor belt pushes the plane forward, will the wheels spin?

LOL...are you intentionally trolling? do wheels spin if the surface they are resting on moves? Yes. The purpose of wheels is to spin...they love it and don't care if they're spinning forwards or backwards.

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12 minutes ago, sevenperforce said:

If the conveyor belt pushes the plane forward, will the wheels spin?

It might if accelerating very fast. Think it was mythbusters who tested driving an car up on an car transporter or driving off one while the transporter was moving. 
it was very non dramatic, the wheels would probably slip a bit but adjusted to new ground speed very fast as the car has way more inertia than the wheels. Now if you kept car in reverse then leaving thing might get interesting but that is an user fail. You would use reverse to move back then neutral on change. 

I read this as spinning like in burnout, not rotating. 

Edited by magnemoe

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Bloody mate, how can this thread gets to page 13 without resolving ? Is this truly greater than any conspiracy ?

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1 hour ago, sevenperforce said:

If the conveyor belt pushes the plane forward, will the wheels spin?

Of course not.  The wheels will remain stationary and move forward with the plane.

 

Now, if the belt exerts force on the wheels and the plane remains stationary, then the wheels would spin.

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2 hours ago, sevenperforce said:

If the conveyor belt pushes the plane forward, will the wheels spin?

Iff the conveyor belt accelerates just the same as the plane does, then they won't spin at all. If it accelerates faster, they would even spin backwards!

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Yes, all you gotta do is remove all the tires from the wheels, lock the brakes, throttle up, take off. Sure, there may be a few sparks, and to "land" you'd have to either ditch into a body of water or be packing a 'chute, but it's entirely possible.

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13 hours ago, Tyko said:
13 hours ago, sevenperforce said:

If the conveyor belt pushes the plane forward, will the wheels spin?

LOL...are you intentionally trolling? do wheels spin if the surface they are resting on moves? Yes. The purpose of wheels is to spin...they love it and don't care if they're spinning forwards or backwards.

Yes, I was being obtuse.

12 hours ago, razark said:

Of course not.  The wheels will remain stationary and move forward with the plane.

And yet even now we have variant answers.

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What if we replace the wheels with treadmills?

1200px-B-36_tracked_gear_edit.jpg

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