Author Topic: plane on a conveyor belt?  (Read 19856 times)

Offline rabbidrabbit

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plane on a conveyor belt?
« on: January 19, 2007, 09:30:28 PM »
A plane is standing on a runway that can move like a giant conveyor belt. The plane applies full forward power and attempts to take off. This conveyor has a control system that tracks the plane's wheel speed and tunes the speed of the conveyor to be exactly the same but in the opposite direction, similar to a treadmill.

The question is:

Will the plane take off or not?

Offline Sandman

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plane on a conveyor belt?
« Reply #1 on: January 19, 2007, 09:35:26 PM »
You need airflow over the wing. Spinning tires do not generate lift.

So... no, the aircraft isn't going anywhere.
sand

Offline Wes14

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plane on a conveyor belt?
« Reply #2 on: January 19, 2007, 09:37:19 PM »
no it wont take-off unless u turn it around so it spins with the plane:D
Warning! The above post may induce: nausea, confusion, headaches, explosive diarrhea, anger, vomiting, and whining. Also this post may not make any sense, or may lead to the hijack of the thread.

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Offline sluggish

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plane on a conveyor belt?
« Reply #3 on: January 19, 2007, 09:41:50 PM »
Sure it will.  Thrust has nothing (or very little) to do with wheel RPM.

Offline CavemanJ

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plane on a conveyor belt?
« Reply #4 on: January 19, 2007, 09:42:34 PM »
The wheels aren't what provide the power and builds speed.  The bird'll fly, it'll just look like the wheels aren't turning at all during the takeoff.

Offline eskimo2

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plane on a conveyor belt?
« Reply #5 on: January 19, 2007, 09:57:23 PM »
The plane will take off, but what you described is impossible.  The conveyer can’t match the wheel speed in the opposite direction; the plane will move forward because the engines are pushing and pulling air, not the conveyer.  The conveyer can speed up all it wants to try and stop the plane but the wheels will just spin as fast as the conveyer PLUS the speed of the accelerating plane.

Offline majic

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plane on a conveyor belt?
« Reply #6 on: January 19, 2007, 10:02:35 PM »
As I understand the question, the conveyor is going in the opposite direction of the plane.  (I think Caveman misunderstood.)  Eskimo has it right, the plane will still move forward, though it will be a bit tougher to get forward momentum because of the added friction of the wheels being pulled backwards.

Offline lasersailor184

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plane on a conveyor belt?
« Reply #7 on: January 19, 2007, 10:05:05 PM »
Simply put, the wheels will spin twice as fast as they would over normal ground.
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Offline Chairboy

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plane on a conveyor belt?
« Reply #8 on: January 19, 2007, 10:10:00 PM »
The plane will take off.  If it was a car, where the power was applied via the tires, then it's stay still, but the thrust is applied elsewhere.
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Offline sluggish

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plane on a conveyor belt?
« Reply #9 on: January 19, 2007, 10:10:45 PM »
What the hell? Didn't anybody see my post?  I was right first!

Offline Sandman

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plane on a conveyor belt?
« Reply #10 on: January 19, 2007, 10:24:28 PM »
http://txfx.net/2005/12/08/airplane-on-a-conveyor-belt/

I get it. The wheels will turn twice as fast and the aircraft will still move forward.
« Last Edit: January 19, 2007, 10:48:23 PM by Sandman »
sand

Offline Maverick

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plane on a conveyor belt?
« Reply #11 on: January 19, 2007, 10:50:14 PM »
Quote
Originally posted by Sandman
You guys are going to have to explain how an aircraft can get airborne if it's not moving forward.


Sandy,

The wheels do not make the plane go forward. The wheels only allow the plane to roll accross the ground and are free wheeling. No motive power is applied through the wheels. The motive power is applied by the airplane engines and are used to move air.
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Offline Debonair

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plane on a conveyor belt?
« Reply #12 on: January 20, 2007, 12:42:27 AM »
no pilot would taxi onto that contraption

Offline APDrone

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plane on a conveyor belt?
« Reply #13 on: January 20, 2007, 12:46:11 AM »
Quote
Originally posted by Maverick
Sandy,

The wheels do not make the plane go forward. The wheels only allow the plane to roll accross the ground and are free wheeling. No motive power is applied through the wheels. The motive power is applied by the airplane engines and are used to move air.



BUT.. to have flight, you must have lift.

To have lift, you must have air moving over the wing.

To get air moving over the wing, you must more than just air from the propeller... you need motion. ( or a strong headwind )

So.. unless the airplane has enough power to pull it self into the air with no runway, it's not going to be flying.

At least, that's the story I'm sticking to.
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Offline Roscoroo

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Re: plane on a conveyor belt?
« Reply #14 on: January 20, 2007, 01:09:39 AM »
Quote
Originally posted by rabbidrabbit
A plane is standing on a runway that can move like a giant conveyor belt. The plane applies full forward power and attempts to take off. This conveyor has a control system that tracks the plane's wheel speed and tunes the speed of the conveyor to be exactly the same but in the opposite direction, similar to a treadmill.

The question is:

Will the plane take off or not?


thats a good question .. I would say no as long as the conveyor keeps up with the wheel speed ....  as for a wing needs airpressure under the wing to create lift ....  

now on anouther point of view if the plane has enough wing/flap area to create  enough lift from the prop thrust it would hop and skip til it ran off the conveyor
Roscoroo ,
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