*light blue touch paper*

[Reaktor4]

The implication is that the plane is stationary because of the conveyor belt. No?

The question is ambiguous.

The conveyor belt would only make a difference if the plane used its wheels to move forward, like cars.

 

[Shamrock]

I still want to know what the **** is up with the thread title.

 

[Codcommando]

Does this plane have rocket boosters, or warp speed?

 

[Raeven0]

The conveyor belt would only make a difference if the plane used its wheels to move forward, like cars.

But a (small) plane generates lift by moving forward on its wheels. If forward movement on its wheels is countered by a conveyor belt moving backward, whence comes the lift?

 

[WaterMelon34]

If planes don't need to move to take off then there wouldn't be a need for verticle propulsion jets. Why drive at over 200mph down a $50,000 runway if it doesn't do anything? Please.

EDIT: Try pushing a piece of paper through the air with your palm at a 20 degree angle moderately fast and see what happens.

 

[OvA]

But a (small) plane generates lift by moving forward on its wheels. If forward movement on its wheels is countered by a conveyor belt moving backward, whence comes the lift?

qft, there's too many paramenters to say for certain one way or another

 

[Raeven0]

qft, there's too many paramenters to say for certain on way or another

Such as tortoises.

 

[Que-Ever]

I still want to know what the **** is up with the thread title.

It was explained in the first post, you would've known if you read it carefully :|

just kidding d:

 

[Shamrock]

It was explained in the first post, you would've known if you read it carefully :|

just kidding d:

THAT IS WHAT I THOUGHT! JUST KIDDING! :flame:

 

[Que-Ever]

THAT IS WHAT I THOUGHT! JUST KIDDING! :flame:

hahaa, gotcha
hey, wait, what's that on your shirt? *flicks nose*

 

[spookymooky]

I thought most small planes actually start flying without their propeller. I.e. they can taxi with their wheels, but the main propulsion comes from the prop...

 

[Smoke]

I can`t take it any longer....WHAT`S THE DAMN ANSWER!!??!?!

 

[Codcommando]

I can`t take it any longer....WHAT`S THE DAMN ANSWER!!??!?!

I dont think you can handle the answer.........

 

[Krynn72]

I dont see how it could possibly take off. It is remaining stationary, not picking up speed. The plane's speed is 0mph, the wheels are moving, but nothing else. When you run on a treadmill, you dont move in relation to the ground. And since its not moving, how can lift be created?

 

[Dr. Nelly Lemon]

I dont see how it could possibly take off. It is remaining stationary, not picking up speed. The plane's speed is 0mph, the wheels are moving, but nothing else. When you run on a treadmill, you dont move in relation to the ground. And since its not moving, how can lift be created?

Wind. A little RC plane or something could possibly be picked up by strong wind.

Same old problem, you need to specify the plane, see?

 

[Glirk Dient]

I dont see how it could possibly take off. It is remaining stationary, not picking up speed. The plane's speed is 0mph, the wheels are moving, but nothing else. When you run on a treadmill, you dont move in relation to the ground. And since its not moving, how can lift be created?

It doesn't matter what the wheels are doing. The wheels don't give the plane acceleration or deceleration. With that that makes the runway irrelivant. The plane grabs at the air and pulls itself forward. Runway means nothing, plane is not attached to it in any way.

 

[Naudian]

Okay I'll try again...

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 opposite direction).

Will it take off? I pick yes.

Picture this: The runway is only about as long as the plane itself, seeing as the plane ain't gonna go anywhere if the runway is countering the movement of the plane's wheels. BUT THE ABOVE STATES: THE PLANE IS MOVING IN ONE DIRECTION. Okay...the plane is moving, but its wheels aren't making it move, so maybe the CONVEYER IS ON WHEELS OF ITS OWN? Wheels that are spinning in the same direction as the plane's except way faster?
If that were the case...the plane wouldn't need wheels at all, as it's just being launched by a speeding platform...
That wouldn't work very well but I still think the plane would be able to take off.

Of course maybe that's not what the statement meant...it's kinda worded badly if the answer is not 'yes'...

EDIT: I change my answer because the plane is not accelerating...well...read my next post...

 

[Reaktor4]

Imagine the plane has instead of a propellor, a chain connected to a helicopter which is pulling it. Does it matter what the wheels are doing? No! It will still go forward because there is a force pulling it forward, and lift when its going fast enough. The wheels are just spinning freely underneath.

 

[15357]

If it was a vertical take-off jet, then yes.

 

[Shippi]

Assume it's a plane powered by jet engines (the type of aircraft really should be specified in the question). The jet engines use air to propel the aircraft forwards. The wheels are there simply because they need a way to land it and because on the ground it needs to taxi about. They don't accelerate the plane. So when the engines start, it uses the air to create thrust and the plane goes forwards. The wheels just spin twice as fast as they would normally to compensate for the conveyor belt. If the plane can move forwards, it can generate lift and take off

 

[JellyWorld]

Edit: I change my vote.

Let x,y,z, be velocity of plane, velocity of wheels (relative to belt) and velocity of conveyer belt respectively.
Let t be time elapsed since start of experiment.

Situation 1: Zero friction

z = -x
y = x-z
lim t -> inf x -> inf
Hence y = x-(-x) = 2x


The first two statements are irrelevant, third statement implies the plane's speed keeps increasing until it hits takeoff speed.

The airplane's speed is unaffected by the movement of the wheels, so even though the conveyer belt pushes back on the wheels the airplane itself doesn't get pushed back and can still take off normally.

And yeah, shippi was right, the wheels move twice as fast as the plane (y = 2x).

 

[Krynn72]

Forgive my ignorance, I dont really know a lot about how a airplane flys. But you are saying that the plane is moving forward when its not. Only the wheels are moving... and as you have clearly pointed out, the wheels dont do anything. So the plane is not moving at all. The plane will never reach a speed higher or lower than 0mph, since its not really moving in relation to the ground (and thus has no air resistance besides what the propellers provide). So the only way I see it lifting off is if the propeller is moving enough air over the wings (or actually under) so that the force of the air pushing up from underneath the wings while it goes under is enough to lift it off the ground.

but does a propeller move enough air to lift the plane by itself? Maybe its just because I dont know how a plane takes off, but I always though you needed to have air pushing up from underneath the plane's wings in order for it to counter act gravity. Isnt that why the plane goes up when you pull the controls backwards, thus tilting the plane to a more vertical angle?

Maybe someone can explain to me how a plane takes off if my way of thinking is incorrect.

 

[$kelet0r]

ok put it this way
th plane is moving forward and at constant velocity - thus it now has massive potential energy due to the resulting friction beneath it
if you were to suddenly retract the wheels very quickly the plane would be airborne (although in all likelihood it would instantly lose control and crash)

 

[Solaris]

How would it fly?

It needs to move through air to get lift. It isn't moving, so no lift.

 

[Greatgat]

How would it fly?

It needs to move through air to get lift. It isn't moving, so no lift.

It's wheels may not be moving, but it's propellor is still pulling it. So, liftoff.

 

[MuToiD_MaN]

So who gets to castrate the people who said no?

The conveyor belt can't stop the plane from moving forward. Unlike a car which uses the speed of its wheels to take off, planes use the air as everyone said before. Even if you had the plane in a wind tunnel (a sort of "air conveyor belt") to keep the engines from pushing the plane forward through the air, the speed of the wind would make the plane lift anyway!

 

[Greatgat]

So who gets to castrate the people who said no?

The conveyor belt can't stop the plane from moving forward. Unlike a car which uses the speed of its wheels to take off, planes use the air as everyone said before.

Well, I said "No" at first, but then thought about it a little bit. Hmm...

/me castrates myself

WHY DID I ****ING DO THAT!?

 

[Naudian]

FFS, the answer must be no! However, the question is too unclear, too many parameters as some people said already. Stop trying to explain the most obvious thing and look at all the parts of the question/statement!

Others have already explained the following, yet ppl still try to explain for the wrong reasons why the plane will not take off....
This is what I get from it:

-The plane is moving forwards at a constant speed (not accelerating)
-The wheels are turning at an increasing speed.
-The conveyer is moving at an increasing speed also, to match the wheels' speed.

Assuming this 'constant speed' of the plane is too slow for takeoff, then the plane will forever be moving at that speed and never accelerate to take-off speed.
So the plane IS moving, but it won't take off.

BUT, if this constant speed was enough to take off with, then YES, the pilot could just pull back on the stick and away it goes

OOOOOORRRRRR, if the speed of the plane was actually meant to be accelerating in the question, then yes it would take off...

Stupid f*cking question...lol

*cuts off one nut for being only half wrong before*

 

[$kelet0r]

but think of it this way - you are running on a treadmill
treadmill stops - what happens?
You keep moving forward
Now imagine that you can move fast enough to become airborne or even to counter the downward force of gravity...

 

[_Z_Ryuken]

Ofcourse it will take off. The only variable that has changed is the speed of rotation of the wheels of the landing gear. They would be turning increasingly faster with the accelleration of the jet and the conveyer until the jet leaves the ground.

Realize however, the wheels are still supporting the weight up to the point of lift off, and there's an increased chance the bearings will fail. If the bearings fail the wheels will grind to a stop and the plane will not lift off.

 

[Vegeta897]

but think of it this way - you are running on a treadmill
treadmill stops - what happens?
You keep moving forward
Now imagine that you can move fast enough to become airborne or even to counter the downward force of gravity...

What are you talking about? You only keep moving forward if you keep running. And no matter how fast you run, you will not gain lift if you are remaining stationary.

What people seem to be incorrectly assuming is that the plane is still, but it's not.

Realize however, the wheels are still supporting the weight up to the point of lift off, and there's an increased chance the bearings will fail. If the bearings fail the wheels will grind to a stop and the plane will not lift off.

Yes, but then there's also the possibility that a meteor strikes the plane! It won't take off then either

 

[$kelet0r]

What are you talking about? You only keep moving forward if you keep running. And no matter how fast you run, you will not gain lift if you are remaining stationary.

What people seem to be incorrectly assuming is that the plane is still, but it's not.

plane moving = person running
imagine person capable of accelerating fast enough to achieve sufficient lift to become airborne

i fail to see your point 0.o

 

[_Z_Ryuken]

plane moving = person running
imagine person capable of accelerating fast enough to achieve sufficient lift to become airborne

i fail to see your point 0.o

Refer to my post above.

 

[Vegeta897]

plane moving = person running
imagine person capable of accelerating fast enough to achieve sufficient lift to become airborne

i fail to see your point 0.o

Ok, but where does the treadmill come in? That has nothing to do with the plane on the runway. When you are on a treadmill you dont move. The plane in the situation we are discussing IS moving.

I fail to see your point.

 

[$kelet0r]

the plane is moving on a conveyor belt which is also moving at the same velocity as the aircraft in the opposite direction!

 

[Vegeta897]

the plane is moving on a conveyor belt which is also moving at the same velocity as the aircraft in the opposite direction!

Your point is...?

A person running on a treadmill is DIFFERENT than the situation we are talking about.

The conveyor belt may be moving opposite the plane, but that doesn't mean a thing because the wheels of the plane are the only things affected by it.

This is COMPLETELY different than a person running on a treadmill.

And even if you were right, which you aren't, what is your point?

Sorry I don't mean to sound like a smartass or anything. No hard feelings

 

[_Z_Ryuken]

Yes, but then there's also the possibility that a meteor strikes the plane! It won't take off then either

If this were an actual scenario that could be tested out the probability of the wheel bearings failing increases exponentially as speed increases.

the plane is moving on a conveyor belt which is also moving at the same velocity as the aircraft in the opposite direction!

Break it down.

Time to initiate take-off.
Brake is engaged, throttle is turned up about 1/2 power. Windspeed is already achieved to a small degree. Brake is released, wheels roll along as the engines create thrust and pushes the plane along. On a normal runway, say the jet hits 50mph at a certain point. On this this conveyor runway, the wheels are doing twice the land speed of the body of the aircraft.
The conveyor has no effect on the aircraft body. It might as well be suspended by strings.
Near the end of the runway, the jet assumes lift off at around 210mph, the wheels are doing 420 or so do to the ground rushing towards the opposite direction.
Landing speed is roughly the same as takeoff and the wheels really are not designed to take twice the speed load that is found under normal circumstances, so this question really is a double-edged sword.

 

[Teta_Bonita]

It all depends on the friction between the wheels and the conveyor belt..... I think.

 

[The Monkey]

No, the only thing that matters is how fast it travels in relation to the air, the speed at the ground is irrelevant. That's why it's easier to take off in headwind.

 

[Teta_Bonita]

okay, smart guy, it all depends on the friction between the wheels and the conveyor belt and its speed in relation to the air.