Author Topic: Airplane on a Conveyor Belt...  (Read 23762 times)

Offline Shuffler

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« Reply #30 on: January 30, 2008, 04:26:00 PM »
The plane will fly.....

The belt can do 500 mph the wheels will freewheel, the prop will still pull it forward to rotation.

Drag at some point will affect the speed but the prop pulls the plane through the air regardless of ground speed hence  IAS, TAS.
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Offline Furious

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« Reply #31 on: January 30, 2008, 04:42:58 PM »
For Funked:

bearing friction.

Offline hitech

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« Reply #32 on: January 30, 2008, 05:07:45 PM »
No thanks, trying to answerer a problem that is not clearly defined is futile.

Assume wheel speed = the speed of the out side of the wheel.

First the wheel and the conveyor only can be traveling the same speed when the plane is not moving. If the plane is moving then the wheel is always moving faster then the conveyor.
So the question does not make any since from the definition of match speed.

Assume wheel speed = the speed at which the axle would move across the ground.

Then for the plane to not move the conveyor must be always at 0 speed.
Again the problem does not make since.

So the question does not make any since from the definition of match speed.

Offline eskimo2

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« Reply #33 on: January 30, 2008, 05:14:45 PM »
Quote
Originally posted by TracerX

I suppose that it depends on the operating limitations of the conveyor belt.  But assuming that there are no limits, the speed would be infinitely large since as soon as the plane moves forward one mph, the conveyor belt will enter a never ending acceleration loop as there is nothing it can do to recover the movement of the airplane, thus eventually accelerating to infinity (assuming it could accelerate that fast).


OK then, answer this:

Here’s a story that simplifies the problem:  (Note that the term wheels in this story refers to wheels and tires)

Identical triplets Al, Bob and Chuck buy three identical bush planes.  Since they live in Alaska, all three brothers buy and install large balloon “tundra tires” and wheels.  The wheels, planes and brothers are identical.  All three planes will take off from a normal runway in exactly 100 feet and at exactly 50 mph.  The brothers fly their planes to an air show in Wisconsin.  At the air show Bob finds and buys a set of fantastic wheels.  These wheels are exactly like the wheels he has on his plane in every way except they have half the mass.  Their mass is distributed in the same proportion as the wheels that he plans on replacing.  Al thinks Bob is silly and is content with his old wheels.  Bob thinks that Al will eventually want a set, so he buys a second set to give to Al on their birthday.

Bob finds a buyer for his old heavy wheels and installs a set of his new lightweight ones.  He loads the second set into his plane so that it is balanced just as it was before.  Bob’s plane now weighs exactly the same as Al’s and Chuck’s, but its wheels have half the mass.

Meanwhile, Chuck runs into a magician who sells him a set of magic wheels.  These wheels are exactly like the wheels he has on his plane in every way except they have no mass.  Chuck installs his magic wheels.  He loads his old set into his plane so that it is balanced just as it was before.  Chuck’s plane now weighs exactly the same as Al’s and Bob’s, but its wheels have no mass.

When the brothers leave the air show they request a formation take off.  They line up wing tip to wing tip and apply power at exactly the same time.  All three planes weigh exactly the same and must hit 50 mph to lift off.  When Chuck’s plane lifts off his wheels stop spinning instantly since they have no mass.  Since they have no mass, they also have no rotational inertia.  When Al’s plane lifts off his heavy wheels are spinning at 50 mph and have considerable rotational inertia.  When Bob’s plane lifts off his half-weight wheels are spinning at 50 mph and have exactly half the rotational inertia as Al’s wheels.  

Where did the rotational inertia and energy in Bob’s and Al’s wheels come from?
How did the rotational inertia and energy now stored in Bob’s and Al’s wheels affect the take off distance of their planes?
We know that Al’s plane will still take off in exactly 100 feet; where will Bob’s and Chuck’s planes take off?

Offline john9001

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« Reply #34 on: January 30, 2008, 05:18:38 PM »
Chuck has a float plane and takes off from the lake.

Offline AKIron

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« Reply #35 on: January 30, 2008, 06:20:39 PM »
Quote
Originally posted by Chairboy
There are some well intentioned but mistaken folks here who say the plane won't take off.  These are the people who, I imagine, concentrate on the GV side of AH.  :D


I don't think anyone here believes the plane won't take off under the conditions in this TV show.

There are some here who fail to understand that the question can be interpreted two ways. One allows the plane to take off, the other does not. They are reproducing the method which will allow the plane to take off.


Ooops, didn't read Curval's proclamation. Okay, one person then.
« Last Edit: January 30, 2008, 06:26:55 PM by AKIron »
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Offline john9001

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« Reply #36 on: January 30, 2008, 07:55:36 PM »
it doesnt matter which way the belt runs, it will have no effect on the plane.

Offline eskimo2

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« Reply #37 on: January 30, 2008, 08:07:50 PM »
Quote
Originally posted by john9001
it doesnt matter which way the belt runs, it will have no effect on the plane.


Be careful, and answer this:

Here’s a story that simplifies the problem: (Note that the term wheels in this story refers to wheels and tires)

Identical triplets Al, Bob and Chuck buy three identical bush planes. Since they live in Alaska, all three brothers buy and install large balloon “tundra tires” and wheels. The wheels, planes and brothers are identical. All three planes will take off from a normal runway in exactly 100 feet and at exactly 50 mph. The brothers fly their planes to an air show in Wisconsin. At the air show Bob finds and buys a set of fantastic wheels. These wheels are exactly like the wheels he has on his plane in every way except they have half the mass. Their mass is distributed in the same proportion as the wheels that he plans on replacing. Al thinks Bob is silly and is content with his old wheels. Bob thinks that Al will eventually want a set, so he buys a second set to give to Al on their birthday.

Bob finds a buyer for his old heavy wheels and installs a set of his new lightweight ones. He loads the second set into his plane so that it is balanced just as it was before. Bob’s plane now weighs exactly the same as Al’s and Chuck’s, but its wheels have half the mass.

Meanwhile, Chuck runs into a magician who sells him a set of magic wheels. These wheels are exactly like the wheels he has on his plane in every way except they have no mass. Chuck installs his magic wheels. He loads his old set into his plane so that it is balanced just as it was before. Chuck’s plane now weighs exactly the same as Al’s and Bob’s, but its wheels have no mass.

When the brothers leave the air show they request a formation take off. They line up wing tip to wing tip and apply power at exactly the same time. All three planes weigh exactly the same and must hit 50 mph to lift off. When Chuck’s plane lifts off his wheels stop spinning instantly since they have no mass. Since they have no mass, they also have no rotational inertia. When Al’s plane lifts off his heavy wheels are spinning at 50 mph and have considerable rotational inertia. When Bob’s plane lifts off his half-weight wheels are spinning at 50 mph and have exactly half the rotational inertia as Al’s wheels.

Where did the rotational inertia and energy in Bob’s and Al’s wheels come from?
How did the rotational inertia and energy now stored in Bob’s and Al’s wheels affect the take off distance of their planes?
We know that Al’s plane will still take off in exactly 100 feet; where will Bob’s and Chuck’s planes take off?

Offline MiloMorai

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Offline C(Sea)Bass

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« Reply #39 on: January 30, 2008, 08:46:02 PM »
Quote
Originally posted by eskimo2

We know that Al’s plane will still take off in exactly 100 feet; where will Bob’s and Chuck’s planes take off?


The runway?

Offline Arlo

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« Reply #40 on: January 30, 2008, 08:57:48 PM »
Dunno if anyone else mentioned this basic element of aerodynamics:

Airfoils create lift via airflow across them .... root to tip creating the most lift.

:D

Offline Treize69

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« Reply #41 on: January 30, 2008, 08:59:38 PM »
You can pull the "ground" 100 mph faster backwards than the plane goes forward, the planes engines don't turn the wheels, they pull through the air.

I am totally confused as to why they think this won't work. This is the dumbest myth I've ever seen them try.
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Offline Chairboy

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« Reply #42 on: January 30, 2008, 09:01:48 PM »
It's a perfect myth because of all the folks like Curval citing "common sense" explanations for why it won't fly.
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Offline WWhiskey

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« Reply #43 on: January 30, 2008, 09:03:58 PM »
show is  over, planes all flew, even the pilot didnt think it would work!
well there you go!
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Offline Treize69

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« Reply #44 on: January 30, 2008, 09:05:23 PM »
Hey, what a surprise, the plane took off just fine. Waste of an episode.


(and yes, I am watching on a delay)
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