So you have a plane and a conveyor belt....Does it take off?

BannedTroll · Post by **BannedTroll** » 01 Apr 2006, 13:58

The plane increases it's thrust and the wheels begin to rotate. The belt compensates for the rotation of the wheels in reverse, as in the belt moves in reverse exactly as fast as the wheels move forward.

And if it matters, it's a nice sunny day and you have good tires, so you get perfect traction on the belt at all times. Your plane also happens to be very powerful and you can give it as much thrust as you like, but the source of thrust is at the back of the plane so it never provides airflow over the wing.

Does the plane take off*?

*question version copied from AT forums.

GreyWolf · Post by **GreyWolf** » 01 Apr 2006, 14:01

the plane will take off. it not using its wheels to create motion.

Basipooned! · Post by **Basipooned!** » 01 Apr 2006, 14:03

No.. If the plane is as moving as fast forward as the conveyer belt is moving it backwards.. There will be now airflow over the wings.

If there is no airflow over the wings there will be no lift under the wings pusing the plane upwards.

BannedTroll · Post by **BannedTroll** » 01 Apr 2006, 14:08

One of you is wrong.

GreyWolf · Post by **GreyWolf** » 01 Apr 2006, 14:18

I am right...as always...

btw, lift is created above the wings

Basipooned! · Post by **Basipooned!** » 01 Apr 2006, 14:22

BannedTroll wrote:One of you is wrong.

ROFL... really???

Greywolf wrote: btw, lift is created above the wings

Oh ja.. I knew that. Even so, how will it take off with no airflow??

GreyWolf · Post by **GreyWolf** » 01 Apr 2006, 14:29

dude, the plane is not relying on its wheels to propel it, therefore the conveyor has no effect on slowing it down...

Post by **Monty** » 01 Apr 2006, 14:38

*whistle*

Moses · Post by **Moses** » 01 Apr 2006, 14:41

I can see this thread getting heated soon....

Law · Post by **Law** » 01 Apr 2006, 14:46

i think the 2 of you are looking at the problem differently and i think both are right. BP is saying if you have a plane with wheels on a conveyorbelt and it's faceing left and the conveyorbelt is moving right and the plane say has a stick behind (or as BT said an engine) it keeping it stationary ( preventing it from moving with the belt) it wont have lift because it has ground speed(relative to the belt) but no air speed.

Gw i think you saying if the belt has a flap that pushes it forward then the plane has zero groundspeed relative to the belt but has airspeed generating lift

tada

GreyWolf · Post by **GreyWolf** » 01 Apr 2006, 14:48

monty, the only effect the conveyor is having is spinning the wheels faster than if the plane was on a normal runway. The jet engines are propelling the plane foreward and there is nothing compensating for that, therefore the plane accelerates and takes off.

BannedTroll · Post by **BannedTroll** » 01 Apr 2006, 14:50

Moses wrote:I can see this thread getting heated soon....

GreyWolf · Post by **GreyWolf** » 01 Apr 2006, 14:52

I will not get into an argument... I have beer keeping my temper nice and chilled...

edit: think it through logically...the only time the wheels on a plane spin s when the plane is already moving. So the plane starts movingforeward, its wheels begin to spin, the conveyor kicks in and turns in the opposite direction, this does not slow the plane dow, it just speeds up the spin of the wheels. But relative to the air around it, the plane is still moving foreward cos that is what the engines are pushing against.

Law · Post by **Law** » 01 Apr 2006, 14:59

gw i see what u saying but BT said ...........

hmm reading BT post again it said...

"source of thrust is at the back of the plane so it never provides airflow over the wing."

so it is propelsion that causes no air movement over the wings

the only way air can move over the wings is if the trust generated by the engine makes the plane travel faster than the conveyorbelt

Basipooned! · Post by **Basipooned!** » 01 Apr 2006, 15:03

GreyWolf wrote:edit: think it through logically...the only time the wheels on a plane spin s when the plane is already moving. So the plane starts movingforeward, its wheels begin to spin, the conveyor kicks in and turns in the opposite direction, this does not slow the plane dow, it just speeds up the spin of the wheels. But relative to the air around it, the plane is still moving foreward cos that is what the engines are pushing against.

good point.. I didn't see it like that initially but now i do.

Moses · Post by **Moses** » 01 Apr 2006, 15:04

The only way the plane wouldn't move forward (relative to the air) would be if the forward thrust (kabillions of Newtons) was countered by some other force. Where does this force come from?

GreyWolf · Post by **GreyWolf** » 01 Apr 2006, 15:11

Law you on the right track, except that you are missing one thing... the conveyor has absolutely nothing to do with the speed of the plane in relation to the air around it. The conveyor is not affecting the air, it is only affecting the wheels of the plane. In other words, the moving conveyor is not causing the air around the plane to also go in the opposite direction, therefore if the air around is not affected, the thrust of the engines will create a foreward momentum, the plane will accelerate and it will take off.

GreyWolf · Post by **GreyWolf** » 01 Apr 2006, 15:49

so..what do I win?

Slasher · Post by **Slasher** » 01 Apr 2006, 16:12

errr your wrong? Sorry , just had to say it...

An aircraft takes off by the air flowing over the flaps pushing it upwards (as the air is forced down... ) Right?

Now, if the aircraft is standing still , even if the wheels are turning, there is no air runnning over the flaps cuasing lift... Still with me?

Still standing air over a flap doesnt give you lift, hence the aircraft just runs in the spot... There we go...

Go think about it a bit... Maybe even draw yourself a sketch...

Take a paper airplane, put wheels on it and let it run on the treadmill... will it take off? Off course not...

CatZ · Post by **CatZ** » 01 Apr 2006, 16:24

School's closed, I'm not going to fry my brain trying to solve this one...
But it's interesting to read what every1 thinks...

Moses · Post by **Moses** » 01 Apr 2006, 16:29

I love the arrogance with which people try to convince others they are right.

Slasher, we have a plane with kazillion Newtons of thrust, you say the plane is stationery, therefore zero resultant force... where is the negative kaziilion Newtons coming from to cancel the engine thrust? Friction

?

GreyWolf · Post by **GreyWolf** » 01 Apr 2006, 16:30

slasher...you don't even know the basic principles of aerodynamics...

the reason a wing provides lift is not cos air is pushing against the bottom. It because the way the wing is shaped, it creates a vacuum above it, and threfore the wing is sucked up. The flaps are use for direction and slowing down(If you ever flew you would have noticed that they only extend them during landing).

the rest of your post is nonsense so I won't even bother...

Slasher · Post by **Slasher** » 01 Apr 2006, 16:52

Grewyolf...

If the wing creates a vaccuum above it, then there needs to be air flowing over it at high speed before it can create the vacuum is it not?

Please, enlioghten me as to where the air is that is supposed to create a vacuum?

Id be willing to put all my money on this bet...

Moses · Post by **Moses** » 01 Apr 2006, 16:57

Slasher wrote:Grewyolf...

If the wing creates a vaccuum above it, then there needs to be air flowing over it at high speed before it can create the vacuum is it not?

Please, enlioghten me as to where the air is that is supposed to create a vacuum?

Id be willing to put all my money on this bet...

You are such a douche.
How much money? I'd bet you, no problem.

Slasher · Post by **Slasher** » 01 Apr 2006, 17:01

Moses wrote: I love the arrogance with which people try to convince others they are right.

Slasher, we have a plane with kazillion Newtons of thrust, you say the plane is stationery, therefore zero resultant force... where is the negative kaziilion Newtons coming from to cancel the engine thrust? Friction ?

*Sigh*

If you read the start post of the thread you will see that the plane is supposed to be standing still whilst rolling on the conveyor belt... Thus, the negative force is the force being exerted on the belt pushing it backwards...

I see no sense in going as deep into the science as newtons if it is obvious that the plane is standing still (Condition = set by user) , where is the air flow coming from?

Accordign to what you two are saying, the plane will do a vertical takeoff till the wheels are FULLY off the conveyor belt and THEN it will start accelerating forward.... ... So you create a vertical take off, which can then be amazingly used to reduce the required runway of a aircraft carrier...