Re: Will it take off?

[QUOTE=MJDub;623238]

Think about it. Aviation has existed for 105 years and has yielded the fucking F-22 Raptor and space shuttle. Would you not think that shortening/removing takeoff roll would be a top priority for the military, especially for the navy? Would they also have already discovered how to do this if we have F-22's and space shuttles? Of course it would be, and of course they would have, but physics (unless you're going the speed of light) has unbreakable laws. That's just reality my friend. .[/QUOTE]

i repeat: the runway would have to be just as long

i repeat: the plane would not just take off vertically

here is how to imagine what is happening: imagine in your head a video from a tower or something of a panorama of an aeroplane about to take off from a half mile long runway. now imagine the plane firing on its engines accelerating and taking off. now replace that entire runway with a massive conveyor belt moving backwards very quickly. again, imagine the plane firing its engines and taking off just like it did in the situation where it was on a normal runway. That is simply what would happen.

imagine a plane doing a close flyby (almost landing) at 300mph, over a conveyor going backwards at 300mph, nothing wrong there huh? the aeroplane is still flying at the end of that yeah? now imagine it lands for a second then takes off? still fit in? when it lands for a second how fast will the wheels be spinning?

you have an idea of a plane rolling on a conveyor going nowhere, but a plane does not generate power from its wheels, like a car (or feet like a person) but on the air. think surface. now think air. those are two different things yeah? surface can move, so can air.

1.if surface is moving backwards and you are accelerating by exerting force on the surface, then yep they might cancel out. like a car on a conveyor or a person on a treadmill.

2.if air is moving backwards and you are accelerating by exerting force on air, then yes they cancel out (whence a big fan might allow a plane to take off vertically ala the air tunnels they test plane parts in)

now....

3. if air is moving backwards and you are accelerating by exerting force on surface, then wahey you can still go forward (think about driving a car 50mph into a 50mph wind, it takes a few more revs cos of extra air friction, but its possible right?

and finally:

4. if surface is moving backwards and you are accelerating by exerting force on air, then you can still move forward. the point in hand.

I hope that clears it up!

Re: Will it take off?

[IMG]http://artfiles.art.com/images/-/Whos-on-First-Print-C10036650.jpeg[/IMG]

Re: Will it take off?

[quote=jamesalvarez;623264] 4. if surface is moving backwards and you are accelerating by exerting force on air, then you can still move forward. the point in hand.

I hope that clears it up![/quote]

How do you accelerate by exerting force on air? The only force exerted on air is via the engines on the wings and that's to provide lift, acceleration is not the point of those engines.

Re: Will it take off?

[QUOTE=feather;623261]Err dude, the conveyor DOES STOP the plane moving forward. They're both at the same speed but in opposite directions. You know, vectors?

Those engines aren't strong enough to pull the plane forward ontop of the motion provided by the wheels, those engines only pull air over the wings.

So at the very best, the plane might generate some lift, but as MJ pointed out, it's also not enough for the plane to take off.

You need the forward momentum + the wing lift, but we have no forward momentum.

Stick your arms up, duct tape hair dryers to them. No go. But maybe if you run and leapt off a building. Youtube please.[/QUOTE]

i know vectors dude, i know (im confident with mathematical mechanics and physics - although thats from having a normal uk A-level education - i am a cognitive scientist postgrad during the day, which means brains, information theory, neural networks and statistics)

its hard to believe, but saying those engines just pull air over wings is too simplistic. the air weighs something yeah? so it takes a force to accelerate and pull the air throught the engine, and that force is matched by the acceleration of the airplane in the opposite direction. think in forces not in speeds its clearer. force causes acceleration, engines cause force, engines cause acceleration. so the plane is accelerating, it will continue accelerating until the friction forces of air stop it at a terminal velocity, which is when the force of accelerating air through the engines matches the force of the air pressure in the opposite direction.

Whence when the space shuttle is falling back to earth, it is being accelerated by the force of gravity, it reaches a terminal falling velocity, but there is evidence of the force of air in the other direction which is the heat generated on the nose of the craft (cos it falls soooo fast).

Re: Will it take off?

[QUOTE=feather;623269]How do you accelerate by exerting force on air? The only force exerted on air is via the engines on the wings and that's to provide lift, acceleration is not the point of those engines.[/QUOTE]

Straight from the horses mouth: [url]http://www.boeing.com/companyoffices/aboutus/wonder_of_flight/engine.html[/url]

Flight is not too complicated, but it took a while for mankind to put the two things together: 1.generate forward momentum by propellor/jet (not wheels) 2. generate upward momentum by forward momentum(through air) on wing

the last point is key, because the engines generate force along the plane, not up like the harrier when it does a vertical lift off. the shape of the wing converts the force along the plane into force up the plane.

think of sail boats, you can travel along the wind, and even slightly into it due to the curve of the sail. both mometna are genereated by forces on air, since thats what a plane works in.

btw the more you argue with me, the closer i get to the precious downloadable sets!

Re: Will it take off?

[QUOTE=MJDub;623238]Higher pressure on the bottom of the wing, because the air is traveling a shorter distance, pushes the wing upward (lift). [/QUOTE]

And lastly the picture you shown is not actually how the wing generates upward momentum, it is the stuff they tell you in school when the real picture is too complicated, (e.g. wave-partical duality)

its actually created by a... :shock: vortex.

Re: Will it take off?

[quote=MJDub;623196]I'm a pilot, and what I said 3 pages ago still stands as substantiated fact.[/quote]

that's a worry :shock:

answer this.

take one plane & conveyor belt. Replace thrust of a jet with thrust with a MASSIVE hand..yes you read right. Cos as a pilot you'd know that the thrust of the motor is propelling the plane against the earth not the belt.

So...this hand {forward thrust}..it moves the plane forward. YES/NO? :roll:

Re: Will it take off?

[quote=Cj Tari;623224]and no, the engines are not pumping air trough the wings, there just sucking up air and tunneling it on a concentrated spot, that being the engine, so you have no air displacement, all the air that the engines are sucking is just going trough the engine, thats it, not trough the tips of the wings, or trough the body of the plane.

[IMG]http://www.offthemarkcartoons.com/cartoons/2007-12-12.gif[/IMG][/quote]

:|

Have a read of what you typed one more time then tell me where the 1000's upon 1000's of thrust the jets create goes? A concentrated spot? Is that like the same spot it goes on every plane just before take off or is this different?

Re: Will it take off?

shiiiit i just read some responses

some of you guys have had waaaaaaaaaaay too many disco biscuits :D