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

[YNM]

14 minutes ago, DAL59 said:

You guys don't now what you're getting into.

Yeah, deathrap !

Spoiler

If we're being honest though, I suggest looking at aircraft carriers. On water and in air.

 

Edited May 14, 2018 by YNM

[Shpaget]

Treadmills have no effect on planes. I have no idea why would anybody think otherwise. Mythbusters have checked.

 

And it works in KSP as expected.

 

 

 

[DAL59]

But the plane was moving forward, so it wasn't an ideal belt.

[Shpaget]

3 minutes ago, DAL59 said:

But the plane was moving forward, so it wasn't an ideal belt.

Of course it moves forward. The belt can not make the plane move backwards if the plane applies thrust and releases brakes.

The friction in the wheel bearings is too low to matter.

[DAL59]

16 minutes ago, Shpaget said:

Of course it moves forward. The belt can not make the plane move backwards if the plane applies thrust and releases brakes.

The friction in the wheel bearings is too low to matter.

It won't move at all, as the treadmill will move faster the faster the wheels try to move.  

[cubinator]

The wheels are not what is propelling the airplane. The wheels will just spin faster on a treadmill while the engines accelerate the plane to regular speed.

[DAL59]

7 minutes ago, cubinator said:

The wheels are not what is propelling the airplane. The wheels will just spin faster on a treadmill while the engines accelerate the plane to regular speed.

But if the engines are moving the plane, the wheels will spin as a consequence.  

[razark]

4 minutes ago, DAL59 said:

But if the engines are moving the plane...

Then the plane will eventually gain enough speed to take off, as there is nothing stopping the wheels from spinning freely.

[DAL59]

5 minutes ago, razark said:

as there is nothing stopping the wheels from spinning freely.

They will spin in place due to the treadmill.

[razark]

Just now, DAL59 said:

They will spin in place due to the treadmill.

Except there's nothing holding the airplane in place, so it will move forward, and the wheels will spin faster.  Once the brakes are off and the engines throttle up, the airplane will accelerate until it reaches flying speed and leaves the ground.  How fast the wheels are spinning doesn't matter a damn to aerodynamics.

[DAL59]

3 minutes ago, razark said:

How fast the wheels are spinning doesn't matter a damn to aerodynamics.

But the wheels are touching the ground, which is moving backward.

[razark]

3 minutes ago, DAL59 said:

But the wheels are touching the ground, which is moving backward.

The wheels are freely spinning.  Airspeed matters to flying an airplane, not groundspeed.  If an airplane with a low enough stall speed is flying into a steady headwind of sufficient speed, it can move "backwards" from the ground's perspective.

Please explain why the speed of the wheels affects the aircraft's speed.

 

Thrust pushes the plane forward.  To keep the plane from moving, there must be some force to counteract thrust.  The wheels spin freely, being unconnected from anything.  Where is the force to stop the plane coming from?

Edited May 14, 2018 by razark

[LordFerret]

That video is BS.

What generates lift on a wing gentlemen? KSP doesn't count, it's not real world physics - and you know that.

[DAL59]

4 minutes ago, razark said:

Where is the force to stop the plane coming from?

The plane.  The plane is making the treadmill move backward.  

[razark]

2 minutes ago, DAL59 said:

The plane.  The plane is making the treadmill move backward.  

How?  The wheels of the plane are unpowered.  The thrust comes purely from the engines.

 

4 minutes ago, LordFerret said:

That video is BS.

Which one?  The KSP one, or the one that actually shows a plane taking off from (what is effectively) a treadmill?

Edited May 14, 2018 by razark

[Geonovast]

Of course it would take off.  Wheels mean nothing.  It's not a car.

If the wheels are so important, why do seaplanes work?  Hm?

[DAL59]

2 minutes ago, Geonovast said:

why do seaplanes work?  Hm?

Seaplanes wouldn't work if there was a current that increased linearly with how fast the plane was moving.  

[LordFerret]

2 minutes ago, razark said:

Which one?

The treadmill.

 

Good gads, I can't believe you people are actually discussing this.

http://www.explainthatstuff.com/howplaneswork.html

[Geonovast]

1 minute ago, DAL59 said:

Seaplanes wouldn't work if there was a current that increased linearly with how fast the plane was moving.  

Yes they would.  You're assuming that airplanes use friction between itself and the surface it's on to propel itself forward like cars do.  That's just not the case.

[razark]

Just now, LordFerret said:

The treadmill.

So the video of it happening is faked?

 

1 minute ago, LordFerret said:

http://www.explainthatstuff.com/howplaneswork.html

Yes, airflow over the wings produces lift.  The point is, there's nothing holding the airplane from moving, it will accelerate, air will flow over the lifting surface, and the plane will take off.

[Geonovast]

Tie the plane's prop to a tree.  Run the treadmill.  If you're right, the treadmill would be unable to run because the plane could not move backwards.  But the treadmill will work fine, because the wheels will just keep spinning, just keep spinning, spinning, just keep spinning, spinning, spinning...

[NSEP]

No, because it needs air to push on the wings in order to generate lift. The plane is essentially standing still while on a treadmill. Wheels have nothing to do with how a plane takes off other than decrease friction on the runway.

[LordFerret]

@razark

The MythBusters video is misleading. If truly a conveyor varied its speed to a point to hold a real airplane steady in one place, which is the concept/question asked in the OP, it would not fly. For a plane to fly, the engines must pull it forward... the forward motion causes air to pass over the wings, which generates lift.

[Geonovast]

3 minutes ago, LordFerret said:

@razark

The MythBusters video is misleading. If truly a conveyor varied its speed to a point to hold a real airplane steady in one place, which is the concept/question asked in the OP, it would not fly. For a plane to fly, the engines must pull it forward... the forward motion causes air to pass over the wings, which generates lift.

But the treadmill will not pull it backwards if it is pulling itself forward. It might have to try an insignificant amount more to overcome the friction from the wheels, but it will take off just fine.

Fine, how about this.

Put a car on the treadmill.  Magically start the car going at a certain speed, and the treadmill at the same speed in the opposite direction.  Car stays put, right?  Because the car has to push against the treadmill to move forward.

Now put the car in neutral, and attach a chain from the front on the car to the back of another car in front of it, which is not on the treadmill.

Start the treadmill, and Accelerate the second car up front.  By your logic, the car on the treadmill will stay put instead of being pulled off.  Right?  Nerp.

 

The planes wheels are always in neutral, like the car.  The prop is the second car pulling it off the treadmill.

Edited May 14, 2018 by Geonovast

[LordFerret]

Again, you're missing it. If the plane is held stationary, wheels spinning, engine roaring, without air passing over the wings there will be no lift - no flight.

Read the link damnit.