[Science Question] Will a plane take off?

[Science Question] Will a plane take off?

This is a question that has caused an equal amount of arguements against each other on another forum I was on last night. See what you all think (try not to search google and post a load of links though).

imagine a plane is set on the beginning of a massive conveyor belt type thingy, the plane intends to take off. The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation.

Can the plane take off?

Re: [Science Question] Will a plane take off?

No, because it's all about speed relative to the air, and this has none.

I don't understand how there was an arguemnt

Thats what i said. There are some seriously intelligent people on the site i was on though as the majority are in advanced IT jobs as coders or technical engineers etc. The pilot voted for no but others were putting forward some arguments that were really confusing me. It still hasn't been settled yet.

Anyone else have an opinion?

That's a worry then, I thought it might the GG board arguing about aerdynamics

Just for the sake of argument, if you put it on a rolling road, which would do what you say but without the conveyor belt, then you'd have a great way of launching planes from a carrier, but it simply doesn't work - you need the air speed to create lift from the wings, surely

The reason the argument has taken off (hah) so much is because people are arguing over whether or not the plane will move forward first, which would eventually equate to enough wind speed. Reasons such as nothing turning the wheels like there is in a car and instead relying on jet engines which push against the air.

The thing that first got me thinking was 'if you set a conveyor to go the same speed in the opposite direction as a scateboard at all times but tied a rope to the end of a fixed point off the conveyor, no matter how fast the the conveyor went to match the speed of the scateboard (that you just happen to be sitting on) - if you pulled on that rope you would move forward.

the answer is no. The plane needs to move to create negative pressure to create lift so if there is no "friction" with the air the plane cannot take off.

By the way, the aircraft carrier was well thought of, i liked that!!

This is a quote from someone that sums it up really..

"If the conveyer is moving at a linear velocity exactly opposite to the wheel's angular velocity times the wheel's circumference, the net linear movement of the plane is zero. Assuming no wind there is no lift generated by the wings and therefore no flight.

This is of course assuming that by 'conveyer belt matches ... the speed of the wheels at any given time,' you meant the linear speed, which is a function of the angular speed and the circumference of the wheel (assuming a perfectly rigid wheel, of course).

Just consider; any fixed wing aeroplane of given mass must reach a certain air speed velocity (in given air density) to provide enough lift to counteract the force exerted by gravitational pull. If the plane is stationary with respect to the air around it, its air speed velocity is zero, and therefore it generates zero lift, meaning that it cannot overcome the force of gravity.

You really don't need to know physics to figure this one out, it's almost common sense."

However, take a look at this site (not the one i was on last night).

http://forums.somethingawful.com/showthread.php?s=&threadid=1723836

The problem with that is he thinks its the wheels turning that make the plane go foward, But a plane uses thurst from the engines to push it forward thru the air, so wheels speed dosn't come in to it, no mater how fast the conveyer belt turned the plane wud still thrust its self forward and take off once the air over the wing reaches the correct speed.

thats what i said, just without all the bollocks

Thats how the arguements started.

I still don't get it though. If the conveyor is set to match the speed of wheels, moving 20 mph 'forward' would result in the conveyor moving 20mph in the opposite direction causing the plane to stay in the same place. No air flow = no lift.

I understand that it's the engines creating thrust to push it forward, and not the wheels but surely because of gravity, and the only point of contact that the plane has with the ground/conveyor before any take off is through the wheels, the only way the plane can move forward is ON its wheels. So, if the conveyor is set to match the speed of the wheels at any given time i fail to see how it can move forward and create any air flow above and below the plane.

IMO, just because it is thrust against the air generated by engines, doesn't avoid the fact that whatever movement occurs has to happen through wheels.

its like if you where standing on the roof of a moving train and u jumped up u would land further on down the carridge but if u do it inside the carridge u land in the same spot....

I dont understand what that is proving apart from the fact that airflow is generated with movement Or is that what you meant?

Our Leader has spoked :worship:

WE HAVE AN ANSWER

Oh well then. Who's up for tea and custard creams?

surely it can take off as its thrust that propells the plane forward not the wheels.... the wheels are free spinning, so the only force the conveyor belt could exert on the aircraft is friction - which the thrust would eventually overcome.

NO (PS I done aerospace engineering at uni)

p.p.s he did it for one year then dropped out

Reasons why arguments FOR takeoff are wrong?