would a plane take off if..

[FireDrgn]

what does the speed of the wheels have to do with anything?  Plane flys independatly of the wheels anyways.   You dont need wheels to take off.   I dont even get it i guess.

[Oleg]

By the way...

http://www.xoxma.com.ua/img/flash/zadachka001.swf

Text at the end of flash says "The Great Physicists".

[Sonicblu]

The plane will take off......

Here is another way to look at it..

Go put a toy car on the treadmill at home. IT doesnt matter if  you (SPIN THE WHEELS ) at 4 miles per hr or 4 million you can still push the car forward with your hand.  The force of the wheels is up and down not horizontal and has no effect on acceleration.

Once you have enough thrust to overcome the friction of the wheels against the converyor you can turn up the speed on the conveyor to 4 million mph. IT wont move the plane backward it just spins the wheels.

Your are spinning Wheels at what ever speed does not affect forward movement.  The effect of spinning wheels is no different that if you had hover skids on the plane.

[kotrenin]

This is why I want a seaplane. 

I agree with eagl's explanation.

The original post by jdbecks states

imagine a plane is sat on the beginning of a massive conveyor belt/travelator type 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.

Can the plane take off?

?

As far as this argument is concerned the conveyor belt will always match the speed of the forward thrust.  The plane cannot roll forward because rolling forward would mean the wheels are going faster then the conveyor belt.  The argument states the wheels and belt always match speed.

the plane becomes an expensive over-sized box fan.

[ChickenHawk]

Even if the treadmill goes to infinity, the thrust from the engine will take the wheels to infinity, and beyond.

[Banshee7]

I guess some people will argue with a wall...

[DREDger]

DRED,

What they're asking is what happens should the treadmill continue accelerating to keep pace with the speed of the wheels, ignoring ALL mechanical impossibilities and looking at it completely from a theoretical standpoint. I misread the OP on that, and it IS a completely different question than what the Mythbusters tested. The Mythbusters were testing the argument that the plane wouldn't take off on a treadmill matching its takeoff speed.

However even viewed as theoretically, the airplane WILL take off because its wheels are ALWAYS moving faster than the conveyor belt. Look at it this way:

An aircraft has a takeoff speed of 60mph with the conveyor belt at 0mph. The plane's wheels spin at 60mph on takeoff. You accelerate your conveyor belt to 60mph, which would match the speed of the wheels at the time the conveyor belt was at a stopped state. However because the aircraft's propulsion system is independent of its wheels, which are free-spinning, it still continues accelerating to its 60mph takeoff speed, with its wheels now spinning at 120mph.

So you accelerate your conveyor belt to 120mph. The plane continues to accelerate until its wheels are spinning at 180mph.

When the conveyor belt is at 180mph the wheels are at 240mph, etc, etc, etc.

No matter how fast the conveyor belt is spinning the wheels are ALWAYS going to be 60mph faster and the plane will take off.

Spot on.  Well said.

[Saxman]

This is why I want a seaplane. 

I agree with eagl's explanation.

The original post by jdbecks states
As far as this argument is concerned the conveyor belt will always match the speed of the forward thrust.  The plane cannot roll forward because rolling forward would mean the wheels are going faster then the conveyor belt.  The argument states the wheels and belt always match speed.

the plane becomes an expensive over-sized box fan.

(Image removed from quote.)

Kotrenin,

Reread my post. The conveyor belt can NEVER match the wheel speed of the aircraft. No matter how fast the treadmill is going, the nature of the plane's manner of acceleration guarantees that its wheels will ALWAYS be faster.

[lengro]

The conveyor belt can NEVER match the wheel speed of the aircraft. No matter how fast the treadmill is going, the nature of the plane's manner of acceleration guarantees that its wheels will ALWAYS be faster.

Or:

Since we agree the plane in reality will move forward, the only way to make the argument true, is to allow for slip between wheels and belt. So - since the conveyor belt is designed to exactly match the speed of the wheel it must be a belt with a very special lubricated surface. (how they designed it however is not our concern).

[Saxman]

Or:

Since we agree the plane in reality will move forward, the only way to make the argument true, is to allow for slip between wheels and belt. So - since the conveyor belt is designed to exactly match the speed of the wheel it must be a belt with a very special lubricated surface. (how they designed it however is not our concern).

Here's an important point to consider:

The chief arguments of the people against are dependent on limiting the mechanical capabilities of the aircraft while REMOVING such restrictions from the treadmill. IE: The treadmill is capable of accelerating to infinite velocities, but the aircraft must contend with the mechanical limitation of its wheels, such as friction of the axles.

To be fairly considered and represented in its purest state, the ONLY factors that can come into play with this problem are: The speed of the treadmill, the speed of the aircraft's wheels at takeoff, (you ca NOT solve this without knowing at what speed the aircraft takes off) and that the aircraft's engine produces thrust independent of the rotation of its wheels--it doesn't even matter how MUCH thrust the aircraft's engine produces.

[Sonicblu]

OK I fell for this one.ooooops.

Can g...d create a rock so big he cant' move it.

I can't type a word of English.

The problem is in the argument.

An argument is only logically valid if it follows the premise. So while the argument is valid. It is what is call unsound because the premise is wrong or invalid.

It violates the law of non contradiction. 

Can you match speed exactly. Our definition of forward movement violates the definition of matching speed. At the same time.

The argument is unsound and cannot be tested as stated.

[CAP1]

I guess some people will argue with a wall...

no they won't

[kotrenin]

Saxman,

reread the Original Post by jdbecks and pay attention to the parts I made bold they are the rules for this argument.  

Quote from: jdbecks on Yesterday at 05:29:35 PM
imagine a plane is sat on the beginning of a massive conveyor belt/travelator type 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.

Can the plane take off?


The Myth Busters had different rules that are not part of the argument in this thread.  The Myth Busters are limiting the conveyor belt to the planes take off speed but the wheels are not.

The equation of jdbecks argument is    x = y + -y

where  x is air speed
          y is wheel speed
   and  -y is conveyor belt speed or the negative wheel speed because The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation. according to jdbecks rules.

that being said if the wheels are going 2 mph the conveyor belt is going -2 mph and airspeed is 0.  Enter any integer for y and you must enter the same integer for -y.


In the Myth Buster equation  the rule limits the conveyor belt to the air speed for take off.  As long as your airplane can provide enough thrust to go at least twice as fast as its takeoff speed it will take off.

[kotrenin]

Sonic,

make sure you explain it to your brother, he's not as quick as you.

<S>
Ko

[Sonicblu]

The Myth Busters had different rules that are not part of the argument in this thread.  The Myth Busters are limiting the conveyor belt to the planes take off speed but the wheels are not.


because that is all you can test in the real world. 

<S> kot