Can Plane Take Off

Paen said:

Touch? salesman.

I was basically just saying that I wasn"t being serious (this is fucking SS for fuck"s sake), and all the professors threw erasers at me for disrupting class.

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Yeah, this thread is a strange occurance for this forum.

The only reason it has stuck around this long is probably because nerds like me can"t talk about this shit IRL outside of the classroom or lab.

Seriously, picture approaching even the town crack whore to pay for an hour to talk about physics. If she were to allow it, she could no longer take herself seriously as a crack whore.

Anal reamage by a horse? No problem. Physics? Hell no. The other crack whores would never let her live it down.

Yermum Onceme said:

the problem isn"t that anyone here is retarded, although most of you are, it is that the question itself is complete bullshit.

If the wheels really do have zero effect and are just freerolling (which is normal for most planes) than no conveyor belt can possibly keep the plane in place. The wheels may be rolling twice as fast, but that fucker is going forward. It"s not staying in place, it"s moving. Horizontally moving along the conveyor belt.

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Exactly. Anyone who answered "No" simply assumed the wheels were the only method of forward propulsion (and since the question doesn"t make it clear that the plane has JET ENGINES behind it, it"s understandable) and concluded that the plane was not moving relative to the ground.

I"ve read this whole thread and have yet to understand how the plane takes off without any upward force?

because you claim that the wheels don"t matter and the conveyor belt has no effect on the thrust in the same breath where you just stated the conveyor belt is literally keeping the plane in place relative to the ground.

It"s an impossible scenario, it"s stupid, and the plane will take off because I motherfucking say so.

If you still don"t get it, a conveyor belt CAN NOT keep a plane from moving forward, unless the plane isn"t actually trying to move forward (engines off, brakes on, etc).

Designz said:

I"ve read this whole thread and have yet to understand how the plane takes off without any upward force?

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Did you see the movie on page 2 with the guy with the fan on the skateboard ? Why does that skateboard move ? AIR DISPLACEMENT ! The same that makes the plane move forward ( only this time with a jet engine or propellor ). It pulls ( or pushes ) itself forward using air ! Forward movement means that the wings cut through the air hence the upward force.

If you don"t understand this you should just accept the fact that the plane takes off. Or maybe think about it again in a few weeks...

Designz said:

I"ve read this whole thread and have yet to understand how the plane takes off without any upward force?

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If the plane moves, then there is upward force. Even with the brakes on, the plane will move because it"s not the wheels that make it go. That"s as simply as it can be put.

The question again.
"An airplane is on a conveyor. The conveyor is set to match the speed of the airplane in the backwords direction. However fast the plane moves, the conveyor moves just as fast."

The part here that says the conveyor is set to match the speed of plane in the backwards direction, that"s the important part. This states that no matter how much forward thrust the plane creates, the conveyor will counteract that forward motion. I"ll repeat that for those that can"t get it the first time; IT COUNTERACTS THE FORWARD THRUST. If the plane doesn"t move forward on the ground, then the damn thing can"t take off. Lift on any plane (other than a VTOL or STOL plane) is ONLY generated by the wings MOVING through the air. If the plane isn"t moving forward in the air (the surrounding ground outside the of the huge ass super conveyor the plane is sitting on doesn"t matter) then it"s not going to take off.

If the person who posed this question disagrees with my interpretation of the question, then STFU. You worded it wrong if you say anything else at this point. Anyone who reads that would say the same thing.

"If the plane moves, then there is upward force. " That"s the point, Galiem. It doesn"t move according to the question.

Under those conditions, my penis could take off.

Dapopeah said:

"If the plane moves, then there is upward force. " That"s the point, Galiem. It doesn"t move according to the question.

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/sigh The entirety of the screenshots forum should understand pretty much all of the physics involved in this by now. I"m pretty sure that even Matt could give a lecture on it by this point.

The plane does move forward. I could give you a thousand conditional models where it does this, but that is not needed because the plane universally moves forward.

There are three reasons for this, and I really can"t type this in again after this or the (what? two?) folks who don"t think that this thread is too long already will by then, and then everyone will get together to eat my lunch. I want to keep my cornbread, damnit!

First, and of equal importance with the second reason, the wheels are not providing the forward thrust. When you spin out the wheels in your car, you lose your forward push. When the plane"s wheels are ineffective, you keep your forward push in the plane because the engines are pushing against the air. If the forward force depended on the ground, then planes would not fly, because there is no ground in the sky.

The second reason is the friction in the system. The two most important and most influencial sources of friction are the contact between the wheel and the belt, and the contact between the belt and the wheels that it is wrapped around. If you add these two, then you get the resistance of the belt to movement.

If we pretend that the entire forward push is transfered to the belt (and it isn"t), then the friction is not equal to the forward push because the coefficient of friction is pretty much always less than one. This means that the wheel"s grip on the belt and the belt"s grip on its components are both less than the force of the plane"s forward thrust.

Thus, while the belt can match the rotation of the wheels, it can not match the force of the plane"s thrust.

Even if both coeffs are equal to one, then the wheels spin out, the plane skids, and although it takes more power than if the wheels were spinning, it can still take off.

The third reason is that the belt is a closed loop, which means that the total momentum of particles on its surface is zero, always. This means that the belt can not, under any circumstances whatsoever, act as a sink for the plane"s momentum. In other words, whatever velocity the plane builds up, it keeps.


There are two reasons that I"m explaining this again. The first is that I love physics, I love unique and creative problems, and I wish that everyone could have a general understanding of it. The second is one of those three.

Nonetheless, if you still don"t understand why the plane takes off, then there"s nothing that can be done for that. If we get to make a scaled down model of this like we want to out here on my end, I will most certainly record the experiment, and then you"ll get to see what is meant here.

Coffee and TV said:

Under those conditions, my penis could take off.

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Damn you C&TV! I just put my penis on a conveyor belt, and now it just hurts like hell!

GaliemVaelant said:

Damn you C&TV! I just put my penis on a conveyor belt, and now it just hurts like hell!

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lollerz, i tricked you!

Stupidity is still going strong I see!

The part here that says the conveyor is set to match the speed of plane in the backwards direction, that"s the important part.This states that no matter how much forward thrust the plane creates, the conveyor will counteract that forward motion.I"ll repeat that for those that can"t get it the first time; IT COUNTERACTS THE FORWARD THRUST.

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NO IT FUCKING DOESN"T. YOU"RE MAKING A FALSE ASSUMPTION. THE WHOLE CONVEYOR BELT BULLSHIT IS A RED HERRING TO DISTRACT YOU. THE WHEELS ON AN AIRPLANE ARE FREE SPINNING AND THEREFORE CANNOT SLOW THE PLANE DOWN, UNLESS THE CAPTAIN IS A DUMB FUCK AND HAS THE BRAKES ON.

TYPING IN CAPS IS FUN.

I"m too lazy to read everyone else"s answers on this, so I"ll just throw my answer in.

It will definetely fly. If you hold a model plane and rev the engines up, and let go of the plane, the thrust from the engine will pull it through the air. As soon as air moves over the wings, lift is created (most people I assume know how this works) and the plane flies.

Now lower said plane down onto a conveyor belt moving at whatever speed. If the engine speed is too low to create lift, the converyor would carry it backward. If the plane has sufficient thrust to make it airborne (create enough lift to move it vertically) it would be the same as letting go of the plane in the above example, and the plane moves forward. If the conveyor is moving faster than the plane, it would carry the plane forward UNLESS the speed was as fast as the plane needed to be going in order to take off vertically. If it was fast enough, the plane would obviously take off.

So the only things that can happen are a)the plane move backwards if the thrust is too low to get it airborne b)the plane takes off and moves forward or c) the plane takes off and moves forward. It will never hover, and beyond a certain point, the speed of the conveyor doesn"t matter.

Whoa there everyone, I think it"s time to pull the plug on this, what I would call failed, joke. The plane doesn"t move at all, we"re all just trying to ruffle your feathers and make you feel like a dumbass. Sorry. But you have to admit, you WERE feeling like quite the dumbass for awhile there, huh? Also, the world really isn"t round, that"s been a running joke since about the week before you were born. Hilarious, I know.

Heh you are all wrong.

The lift is produced by airflow over the wings, nothing else, not the prop, not the afterburner, the AIRFLOW over the wings. This explains why there are catapults on aircraft carriers, why the wind speeds are a factor in liftoff, the airflow over the wings is the only factor in takeoff. A prop, an afterburner, and a catpult are all methods of thrust to achieve the necessary airflow over the wings.

Take airplane X, chop off its wings, its max land speed is 250mph lets say.

If the conveyor belt Y can match the 250 speed, the plane will never take off. The wheels will spin at 500 mph assuming they do not fail, and the wings will have zero airflow over them, generating no lift whatsoever for the plane to achieve flight.

The plane MUST get airflow over the wings to liftoff, the prop doesn"t create vertical lift, it creates horizontal THRUST, likewise the afterburner creates horizontal thrust.

Research on the web about how wings works, how flaps work, etc.

The point about windspeed gave up the answer, when there is a tailwind you have to move faster down the runway to lift off, and when there is a headwind it takes less speed down the runway to create the necessary airflow over the wings for lift.

You could put said plane in a windtunnel, and attach it"s nose to a tether, and it would generate lift while motionless, it is the high pressure under the wing that generates the lift. Wings are curved to allow air to pass over the top of them faster generating lower pressure over the top of the wing, and higher pressure by the slower air under the bottom of the wing, that is how lift is generated.

It is the airflow over the wings that creates liftoff.

If the conveyor belt could match the full throttle speed of the plane, and have the plane essentially sitting still in relation to the tower, only spinning it"s wheels against the conveyor at max throttle not moving down the conveyor due to a lack of more horsepower, then the plane would not have sufficient airflow over the wings to generate lift.

The plane would sit there.

Salacious, I already spilled the beans. You didn"t have to write all that.

Heh you are all wrong.

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Man you"re an idiot.

If the conveyor belt could match the full throttle speed of the plane, and have the plane essentially sitting still in relation to the tower, only spinning it"s wheels against the conveyor at max throttle not moving down the conveyor due to a lack of more horsepower, then the plane would not have sufficient airflow over the wings to generate lift.

The plane would sit there.

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Show me a fucking airplane that gets it"s acceleration and speed by spinning it"s goddamn wheels, you moron.

For the 100th time, the conveyor belt is essentially irrelevant. It is unable to impart any significant force upon the airplane, unless the pilot is a fuckwad and has the brakes activated. Therefore the thrust generated by the plane"s engines/props/rubberband is not counteracted by another force, and since there is a significant force from the above the plane will accelerate. Therefore air will flow across the wings and generate lift.

Again, the conveyor belt is essentially irrelevant, if you disregard important considerations like the wheels of the airplane rotating far faster than they were designed for and so on.

This looks like it might fly.

http://www.georgespratt.org/CarPlane/CarPlane22.jpg

BAM.

EDIT: BAM part 2.

*brain splodes*