plane on a conveyor belt?

[Terror]

If the acceleration is slow, wouldn't the rotational inertia forces be extremely easy to overcome.  It does not take a huge amount of energy to get something rolling and even less to get it rolling a little faster.  

Since we do not have to move forward from 0 to infinity instantly, but rather accellerate from 0 to ~100 knots over a period of time, the engine should be able to overcome the "rotational moment" factors relatively easily.  Worst case, the inertial forces that need to be overcome from accellerating the rotational speed of the wheels would be doubled from a normal take off.  Seems to me the airplane would still be able to take off.

Maybe hitech should model this hypothetical runway in AH!

Terror

[Terror]

From a Physics Forum on this exact topic:

459 Pages, 6876 replies!!

Physics Forum Thread

Hitech,  this thread may just fill your HD space !!

Terror

[JB88]

wow.

that's a freakin lot.

[Debonair]

OMG physics post potatos lololol:O nurds

[john9001]

the plane will fly, some of you don't understand what a wheel does.

A  wheel is a circular device capable of rotating on its axis, facilitating movement or transportation or performing labour in machines. A wheel together with an axle overcomes friction by facilitating motion by rolling. Common examples are found in transport applications.


<<<>>>>


a airplane has wheels so it can roll freely over the ground or conveyor, and don't tell me the wheels are going to blowup, if you can build a conveyor the goes that fast, you can build wheels that don't blowup.

the thrust of the engines will push the plane forward and the conveyor has no way to push back against the plane, all the conveyor will do is spin the wheels.


this is like trying to teach a caveman about electricity

[Casca]

Of course it will fly.

[JB88]

you keep telling yourself that you can stop any time you want.

but this is physics...and physics is the hard stuff.

seek help.

[eskimo2]

Originally posted by Terror
From a Physics Forum on this exact topic:

459 Pages, 6876 replies!!

Physics Forum Thread

Hitech,  this thread may just fill your HD space !!

Terror

LOL! IN!

[Mini D]

Originally posted by eskimo2
You took high school and/or college physics?  Right?
Don’t you remember solving theoretical problems with frictionless surfaces, pulleys and wheels?

Of course I did. At the end of the experiement, we'd also figure out the % error.

We did not ignore friction. We did not pretend infinity was measurable. We did not do one and dismiss everything else.

[JCLerch]

We need a simple poll.

The plane will take off normally, while the airplane wheels spin at the max speed the conveyor belt is capable of achieving, PLUS the speed over ground of the aircraft.

Yes or No












then we can laugh at the ppl that answer no

[Hap]

Polish scientist studies flies.  

Commands fly to fly.  Fly flies.  Notes same in notebook.

Takes 1 wing off.  Commands fly to fly.  Fly flies in circles.  Notes fly with 1 wing flies in a circle.

Takes the other wing off.

Commands fly to fly.

Fly just sits there.

Commands fly to fly, again.

No joy from fly.

Writes in notebook:

Fly with no wings becomes deaf.



hap

[hitech]

Ok I am almost going off the deep end now, getting very close to drawing a theoretical case and working out the mathematical proof.

Mini D: Picture a 10000 LB wheel suported by a bearing and none of it sides are touching. Picture your slef trying to turn the wheel. Obviously you would have to push fairly hard to get it turning. Now stop pushing, the wheel will very gradually slow to a stop. Where all your force went is into the rotational acceleration of the wheel. It is derived from F = m * A. (Force = Mass * Acceleration). Sorry can't pull the rotational version out of my head at the moment. (no pun intended)

Now when you are pushing on the wheel you are creating a torque on the wheel (I.E. making it turn) but you are also creating the same force on the axle and in the same direction you are pushing.

In the airplanes case, this force would be transmitted to the airplane, and if the force of the conveyor equaled the thrust of the plane. The plane  would not move.

HiTech

[lukster]

This whole discussion has ignored the pilot. Chuck Norris laughs at infinite speed conveyor belts. He'd have the plane flying in no time.

[Casca]

We all must have way too much time on our hands.  I understand what the won't fly side is driving at but it doesn't apply in this instance.  I think this is because people are trying to answer different questions.  This, in turn, is caused by the wording of the question at the beginning of the thread.  I think what is meant (based on the HiTech Plano quote, the Boortz article and the ginormous thread) is that the conveyor belt speed matches the speed of the airplane.  If the airplane is going 60 knots the conveyor belt is going 60 knots.  If the airplane is going 0 knots the conveyor is going 0 knots.  If this is true the airplane will fly at the normal airspeed with two times the wheel speed as has been previously pointed out.  

Try this.  Ask the same question and substitute the wheels on the airplane with skis and cover the conveyor with ice.  The airplane would behave vitually identically in either case the only difference being the difference in friction between skis in one case and wheel bearings and rolling friction in the other which would be negligible for the purposes of the thought experiment.

[hitech]

Casca: Obviously you understand the problem, eskimo and I just changed the problem to be, the speed of the conveyor is not matched to the speed of the plane but rather continually increased to match the force of the Prop.


Hitech