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Aeroplane Riddle

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A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?

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A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?

Interesting, I would say no, because it needs the resistance of airflow for the wing to work and consequently take off.

aerofoil.jpg

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A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?

Nope, the plane needs air moving over the wings to generate lift (as quickly thought of off the top of my head)

Do I get a prize?

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A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?

no airflow over the aerofoil == no lift.

what i don't understand is how a plane can fly upside-down. where's the lift coming from then?

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no airflow over the aerofoil == no lift.

what i don't understand is how a plane can fly upside-down. where's the lift coming from then?

This was explained in the game flight unlimited around 1995. The wing is still an aero foil however because of the reversed forces an airplane has to fly tilting upwards (to the sky) to maintain a straight path as without this lift is generated downwards until you change the angle of attack so that the wing which faces the sky (the bottom) has a longer distance for air to travel than the top hence generating lift.

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no airflow over the aerofoil == no lift.

what i don't understand is how a plane can fly upside-down. where's the lift coming from then?

Possibly the ailerons or flaps? They are down when a plane wants to go down and raised when it wants to gain height as far as I understand it. If the plane is upside down maybe the ailerons are reversed e.g down is up and up is down?

Mind you, you would'nt want to f*ck that up.

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A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?

Yes, if the wind is strong enough.

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A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?

I keep getting distracted by how fast the conveyor belt would have to move to cancel out the thrust from a jet plane, whether the wheels would then melt or explode, and whether there would be a nice rewarding explosion afterwards; the question may be a bit easier if you just said the handbrake was left on. As the other posters have said it just needs air moving over the wings so if you were to whack a few *efficient* propellers behind each wing you should be fine to take off vertically.

Edit: Looking at it from a more pragmatic viewpoint though, no

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This was done on MythBusters. Can't remember the outcome. Might want to check Google or MB website.

It was busted.

Basically because the engine does not power the wheels.

Friction is also important.

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Guest X-QUORK

A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?

No. Ground speed is not relevant, only airspeed over the wings. In your example there will be no airflow over the wings, and therefore, no lift.

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If you watch a big jet taking off, you'll see exactly the same effect. The wings are flat(ish) to start with, and as they start to generate lift, they bend. Try looking for WWII Lancasters carrying a heavy load, there is a serious bend in these.

To answer the op:

Ground speed = infinite, air speed = zero, you're staying on the ground.

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Ground speed = infinite, air speed = zero, you're staying on the ground.

Going to need some new tyres too.

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What happens if you turn the engines off and put it on a turntable that's spinning round really fast? Does it take off, tip over on one side, or what?

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What happens if you turn the engines off and put it on a turntable that's spinning round really fast? Does it take off, tip over on one side, or what?

Tips over as the G-Forces go to work and then slides off the turntable.

There is a youtube video of some chavs on a roundabout somewhere that illustrates this phenomenon well.

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It depends on the type of plane. If it's a jet then no chance but if it is propeller driven and the engine's are in front of the wings (more than one engine) then the wind generated by the propellers could in theory be enough to lift the airplane off the moving runway. It would then move forward above the runway and resume normal flight as lift increased due to forward speed. Unlikely there is a plane that could do it but maybe a Hercules with huge propellers and stripped down to minimum weight.

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Tips over as the G-Forces go to work and then slides off the turntable.

There is a youtube video of some chavs on a roundabout somewhere that illustrates this phenomenon well.

Oh, that's a brilliant video...the one where they rig up a playground roundabout to their 50cc scooter?

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Oh, that's a brilliant video...the one where they rig up a playground roundabout to their 50cc scooter?

Yup thats the one.

A Darwin award chavtacular!

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Yup thats the one.

A Darwin award chavtacular!

I like the way his head flicks back just nanoseconds before he becomes airborne.

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  • 145 Brexit, House prices and Summer 2020

    1. 1. Including the effects Brexit, where do you think average UK house prices will be relative to now in June 2020?


      • down 5% +
      • down 2.5%
      • Even
      • up 2.5%
      • up 5%



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