Author Topic: Plane on a conveyor belt  (Read 6718 times)

Plane on a conveyor belt
Reply #30 on: January 22, 2007, 13:18:17 PM
Quote from: M3ta7h3ad
Push a car... now push a car on a treadmill that is so well lubricated theres next to no resistance, as the wheels roll, the road will move backwards. Keeping the car where it is.

Unless you the driving force is on the treadmill as well that is crap, if your pushing the car from a solid bit of ground the fact the treadmill is moving will make no difference the car will have to move the way your pushing it.

Plane on a conveyor belt
Reply #31 on: January 22, 2007, 13:18:56 PM
No it wouldnt.

a rocket on wheels horizontally (rocket car), the rocket will attempt to move forward, in order to do so the wheels WILL NEED TO ROTATE! (assuming that they arent siezed or something equally abstract).

The MOMENT the wheels rotate... the treadmill rotates. From then on in, those wheels will be spinning like crazy, but that treadmill in theory will keep on right with em.

Plane on a conveyor belt
Reply #32 on: January 22, 2007, 13:20:07 PM
yeah and all the time the car will be accelerating as the force is applied from the jet not the wheels on the road

Plane on a conveyor belt
Reply #33 on: January 22, 2007, 13:21:13 PM
Quote from: Binary Shadow
Quote from: M3ta7h3ad
Push a car... now push a car on a treadmill that is so well lubricated theres next to no resistance, as the wheels roll, the road will move backwards. Keeping the car where it is.

Unless you the driving force is on the treadmill as well that is crap, if your pushing the car from a solid bit of ground the fact the treadmill is moving will make no difference the car will have to move the way your pushing it.


no... your seeing movement as a floating car.

The car in order to move forward, will need to roll its wheels.

When it rolls its wheels...

THE ROLLERS WILL ROLL!

Therefore any forward movement completely gets cancelled out. You just come flat up against a non-moving car whilst trying to push it. You are pushing against a wall to all intents and purposes, on wheels... on rollers... therefore on solid ground. only the wheels are spinning realllllllllyyy fast.

Plane on a conveyor belt
Reply #34 on: January 22, 2007, 13:21:43 PM
get a treadmill, jump on it with roller skates on, then pull yourself forward with your arms, you will move forward

Plane on a conveyor belt
Reply #35 on: January 22, 2007, 13:22:14 PM
Quote from: Binary Shadow
yeah and all the time the car will be accelerating as the force is applied from the jet not the wheels on the road


No... the wheels will be the only things moving on the car.

How do bearings work mate?

Plane on a conveyor belt
Reply #36 on: January 22, 2007, 13:23:28 PM
that and the turbine in the jet engine pushing it all fowards doesnt matter if the wheels are spinning at mach 2 itll go and go

Plane on a conveyor belt
Reply #37 on: January 22, 2007, 13:27:10 PM
Quote from: Binary Shadow
get a treadmill, jump on it with roller skates on, then pull yourself forward with your arms, you will move forward


Only because your roller skates have less resistance than a treadmill.

Put a nice loosely moving treadmill there and I could quite happily get towed while wearing roller skates if I wanted.

When I say towed, I mean hold onto a bar mounted to the front of the treadmill much like the practice watersking units :)

Plane on a conveyor belt
Reply #38 on: January 22, 2007, 13:28:35 PM
Quote from: Binary Shadow
that and the turbine in the jet engine pushing it all fowards doesnt matter if the wheels are spinning at mach 2 itll go and go


your saying that a jet engine will defy the laws of physics.

TO GO FORWARD do you admit in a normal situation, the plane is required to make its wheels rotate, in order to get sufficient airflow over its lift surfaces?

Plane on a conveyor belt
Reply #39 on: January 22, 2007, 13:31:18 PM
to move foward the plane has to apply a force in the direction that overcomes the near frictionless wheel bearings.. oh yes i can see that being an issue for 4 olympus engines capable of dragging an airliner to mach2 and beyond

Plane on a conveyor belt
Reply #40 on: January 22, 2007, 13:36:10 PM
Quote
Or

Speed of Wheels - Speed of Conveyor = Speed of Plane

In the statement of question, Francisco stated:

"The conveyer belt is designed to exactly match the speed of the wheels
at any given time, moving in the opposite direction of rotation."
He did not state the speed of the aircraft, but the speed of the wheels.
Given the formula above the forward speed of the plane should always be
zero and can not generate enough lift to takeoff.


is the viewpoint im taking on this. (googled it).

If the treadmill is intended to match the speed of the airplanes wheels at every moment, then frictionless wheel bearings mean naff all. Wheels will be spinning... treadmill will be spinning just as fast. To someone standing outside the treadmill plane system it will appear stationary, onboard ground speed will be sky high, yet airspeed will also be 0.

Airspeed is what allows the plane to take off. NOT GROUND SPEED. So... there.

Edit:

Or in your words, in relation to the ground (treadmill) the plane will be moving at mach 2. in relation to the air, itll be stationary.

Plane on a conveyor belt
Reply #41 on: January 22, 2007, 13:39:26 PM
what a load of crap, whoosh it will be hurting down that runway and you better hope the treadmill is able to travel at take off speed without blowing up

theres no resisting force!!!

Re:Plane on a conveyor belt
Reply #42 on: January 22, 2007, 13:41:32 PM
The plane takes off.  Now move along folks.

Id explain it, but in all honesty trying to get simple physical concepts through to a certain person on these boards is like slamming ones head in a vault door.

All Ill say is this:  The wheels are freely rotating.  Their rotation doesnt exert a force on the plane itself.  The plane is "pushing" itself forward off the air around it, not the road.

Plane on a conveyor belt
Reply #43 on: January 22, 2007, 13:41:35 PM
let me put it simply

concorde sat on end of convayor, has 4x35190 lbf thrust being produced, whats going to stop it? theres no way the wheels spinning will slow the aircraft down as the friction is minimal

Plane on a conveyor belt
Reply #44 on: January 22, 2007, 13:44:54 PM
There has been no physical constraints put on the treadmill other than "it has been designed to match the speed of the wheels at every moment".

At least thats the viewpoint im taking it from, as thats the traditional method of discussing this.

Youve just clarified for me that the wheels would have to turn in order for the plane to move forward.

Ive just told you the treadmill would move accordingly.

So... the wheels will move forward, the treadmill will move backwards.

Meaning that the wings stay where they bloody well are, and the plane doesnt take off.

Do you really need me to spell it out for you some more?

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