Brain Plane

[Gaijin De Tokyo]

A plane is sat on the beginning of a massive conveyor belt arrangement, as wide and as long as a runway, and 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.
There is no wind.
Is it possible for the plane to take off?
Explain why?

 

[AtlanticBlue99]

no it can not. repost, and planes connot take off unless the conveyer belt makes a certain ratio of air pressure below and above the wings to comfort flight...

 

[Tim]

Yes it will take flight...

Ground speed is not a governing factor in flight. The plane will accelerate as normal and lift off once it reaches the proper speed required since the conveyor belt will have no effect on the thrust of the engines. It's not the wheels on a plane that provide the forward movement, it's the jet engine or prop.

 

[99mustang232]

Re: RE: Brain Plane

no it can not. repost, and planes connot take off unless the conveyer belt makes a certain ratio of air pressure below and above the wings to comfort flight...

right

Yes it will take flight...

Ground speed is not a governing factor in flight. The plane will accelerate as normal and lift off once it reaches the proper speed required since the conveyor belt will have no effect on the thrust of the engines. It's not the wheels on a plane that provide the forward movement, it's the jet engine or prop.

wrong

in essence the plan would be stationary, how can it get the needed lift to take off?

 

[Tim]

Re: RE: Brain Plane

wrong

in essence the plane would be stationary, how can it get the needed lift to take off?

So if you were wearing your pink roller skates standing on that same conveyor belt with a rocket engine strapped to your ass.... you're saying that you wouldn't move because a backwards running conveyor belt is spinning under your free spinning wheels? How does the conveyor belt even come into play??? :dunno

 

[99mustang232]

I wouldn't be wearing pink roller skates, maybe ab, but not me... let me make a similar anology you might understand.

coveyor is to plane as 4wheel dyno is to AWD import

like walking on a treadmill

 

[OUZBnd]

YES, it will take off. Planes are not powered by the landing gear, they are powered by thrust from the jet engine.

 

[OUZBnd]

Re: RE: Brain Plane

I wouldn't be wearing pink roller skates, maybe ab, but not me... let me make a similar anology you might understand.

coveyor is to plane as 4wheel dyno is to AWD import

like walking on a treadmill

Thats not a valid analogy. The car is propelled by the WHEELS, not a jet engine. The airplane is propelled by THRUST, not friction from the wheels interacting with the ground. Think this one through again.


IFF this question used a car as an example then sure, your dyno anology would be great. But then again there would be nothing perplexing about the question if a car were used in the example, would there?

 

[AtlanticBlue99]

A plane is sat on the beginning of a massive conveyor belt arrangement, as wide and as long as a runway, and 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.
There is no wind.
Is it possible for the plane to take off?
Explain why?

i thought the wheels roll at a rate proportional to the airplane's movement forward. so, the conveyer belt matched the speed of the plane, if so, no flight... flight has nothing to do with speed, just air pressure, and if the plane is stationary, no difference in pressure, no flight...

 

[Tim]

Re: RE: Brain Plane

A plane is sat on the beginning of a massive conveyor belt arrangement, as wide and as long as a runway, and 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.
There is no wind.
Is it possible for the plane to take off?
Explain why?

i thought the wheels roll at a rate proportional to the airplane's movement forward. so, the conveyer belt matched the speed of the plane, if so, no flight... flight has nothing to do with speed, just air pressure, and if the plane is stationary, no difference in pressure, no flight...

Yes, the wheels roll at a rate proportional to the airplanes movement...
But it will still gain speed. Relative to an observer standing next to the conveyor, the plane will accelerate due to the thrust of the jet engines that are pushing on the air behind the plane. The jet engines don't push against the moving conveyor belt.

 

[99mustang232]

someone call mythbusters!

first of all i agree the planes wheels have nothing to do with the plane as do the wheels on a car, but i think the big picture that is being missed by all is this statement about the majic conveyer belt: "The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation. There is no wind."

so understanding how a plane takesoff: the jet or prop plane has the flaps up and gets up to speed lets say 160mph, as it lowers the wing flaps, the lift is created by the oncoming airflow, which is being generated by the air thrust (while on a stationary tarmac) and thus the plane is airborne, if the plane does not lower the flaps it will never leave the ground unless at some incredible speed where the wing's angle produces the lift.

now back to this scenerio: as the plane starts it's engine(s) and starts to thrust the plane forward it still has to roll on the wheels right? the wheels are the buffer between the plane and the ground. as the plane starts to thrust forward the ground under the plane is moving the opposing direction at an equal speed as the wheels are rolling forward with this "majical conveyor". if you were standing on stationary ground next to the plane observing this the plane would "appear" to be standing still, however it is actually moving at a high rate of speed, in comparison to the non-stationary conveyer belt, but not to objects not on the conveyer belt. given that we know there is no wind, the only airflow being generated would be from prop or jet engine. since a jet engine sits aft the wing it would have no effect on the wing flaps, however since the prop pulls the plane their would be some sort of aiflow generated, but i must admit would have to be going hella fast to produce the amount of airflow needed to generate the lift prior to any given number of possible failures.

so my question is where does the plane get it's lift to takeoff? and we aren't talking about herrier's here.

 

[Tim]

Ok let's look at this from another angle...
If you took the wheels off a plane and replaced them with ice skates, would the planes engines be able to push it along on ice until forward speed reached a point at which the plane would take off?
Yes...
Now would it make any difference if the ice were moving forward or backward at any speed?
No...
So what makes free spinning wheels any different?

The plane will accelerate to take-off speed regardless of ground speed as long as the wheels are free spinning because the wheels have nothing to do with the acceleration of the plane.

 

[IntruderLS1]

Ha-Ha. Fight the good fight Tim.


For any who doubt, just remember to live by the rule that Tim is always right in one way or another, and you'll save yourself a lot of thinking on your own.

He's absolutely correct in his explination of this magic conveyor belt airplane thingy.

Oh, and for the record, a plane does not need to have flaps down to generate enough lift for flight. Flaps extend the top surface of your wing, and help you generate more lift at lower speeds, but they aren't required for take off.

 

[OUZBnd]

Wow. How is this not so obvious even after it is explained. WHEELS HAVE NOTHING TO DO WITH PROPELLING A PLANE. Take the wheels completely out of the equation.

When an airplane is in the air flying does it matter if the wheels are spinning backwards, forwards, or sideways? No. You could attach a 3000hp motor to the axle of that wheel and spin it at 20,000 RPM backwards and it wouldn't make a damn bit of difference. The only thing that matters is the THRUST that is being created by the jet engines.

Lets look at this from yet another angle that doesn't even involve thinking about the physics question.

Why would anyone ask this question if the answer were as simple as saying "no, it would not take off because the wheel and conveyor cancel each other out" No offense, but a 4th grader can point out that logic. If you know nothing about the physics behind a plane, then you should still be able to answer this question merely by knowing that it is a 'brain teaser' and thus realizing that 99% of the time the obvious answer to a brain teaser is incorrect. Otherwise, what would be the point.