Now, Blue, you made me read your entire post. I ask the same of you and all you non-believers...

Quote:
Originally posted by BlueSky:
For our purposes, let's define "roll" as rotation over stationary ground, resulting in movement. "Movement" means covering a given distance. Agree? Good.
You're WRONG! Roll is defined as moving along a surface by revolving or turning over. That surface doesn't have to be stationary as described in the convyor belt scenario.

Quote:
Originally posted by BlueSky:
For an aircraft at rest on the ground with the landing gear down, how does [b]any kind of propelling force - a tow tractor, people pushing, engine power, or a downhill slope as examples - become forward motion? How does the plane itself accelerate forward? Move from point A to point B? How does ANY FORCE applied to the plane result in forward movement?[/b]
Are you serious? Have you taken ANY kind of physics classes at all?!?

To ALL of your questions here...There is a force being applied to propell the airplane forward. It is an outside source, but that source is great enough to be able to move the airplane from point A to point B.

Let's review Newton's three laws of physics. They will disprove your entire statement:

I. Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

II. The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); in this law the direction of the force vector is the same as the direction of the acceleration vector.

III. For every action there is an equal and opposite reaction.

Quote:
Originally posted by BlueSky:
One thing must happen for the plane to move. The tires must roll. It doesn't matter how that propelling force is applied but for that aircraft to move forward, the tires, mounted on their freewheeling, unpowered wheels, [b]must roll. That's why we need brakes and wheel chocks, right?[/b]
You don't seem to understand...it DOES matter what the propelling force is. There are two forces at action here....the force that the conveyor is putting on the wheels, and the force the engine is creating. The ONLY THING that will work against the engines is the air itself. UNLESS the engine is resting on the conveyor belt with no wheels below it. Then, the conveyor is acting on the engine itself because of the downward force of gravity applied to the engine to push it directly into the conveyor belt. The wheels are there to take that force off of the engine so the engine will work independantly of the wheels.

Quote:
Originally posted by BlueSky:
What happens when the tires, mounted on their freewheeling, unpowered wheels, roll? The plane moves along the ground. This is, IMHO, one missing link for the WFers - the rolling tires only travel forward because [b]the ground is stationary. That distance, as we know, is a certain amount per tire rotation depending on their size.

But when the belt is added, the ground under the plane is in effect moving in the opposite direction. Forward movement is no longer the result of applying any kind of propelling force because...why?
/[qb]

Because the wheels are not the propelling force...the ENGINES are!!! Simple physics!!!

Quote:
Originally posted by BlueSky:
[QB]The tires are no longer rolling along the stationary ground, they're rotating in place. And since the freewheeling, unpowered wheels they're mounted upon are on an axle attached to the plane, if the tires are not moving forward, neither is the plane.[/b]
See, THIS is where all you that say it can't fly are being hung up. The wheels and tires are not doing the propelling. The original statement states that the conveyor is matching the plane's speed. Now, for it to match the plane's speed, it's going to make the wheels spin at twice the plane's speed in the opposite direction. Thing is, the wheels are assumed to be nearly frictionless due to the ball bearings. How in the hell is a conveyor belt going to stop the wheels if they can ALWAYS travel MUCH faster than what the plane can travel? If the wheels are travelling at 10x the speed of the airplane, the airplane will STILL MOVE FORWARD because the ENGINES DON'T HAVE ANY FORCE ACTING ON THEM!!! THE WHEELS HAVE FORCE ACTING ON THEM.

Quote:
Originally posted by BlueSky:
And guess what? That pesky friction? It's WFer missing link #2. [b]You don't need enough to stop the plane, you only need enough to make the tires rotate. That's why the "perfect frictionless ice" scenario works, because the need for the tires to roll is effectively removed because there's not enough friction to make them rotate.[/b]
The bearings are there to provide a nearly frictionless surface. Similar to what the ice would produce.

Think of this.....the friction created by the wheels is also being created by the conveyor if we presume that the conveyor is on a similar system of wheels and bearings. If this is the case, how will the conveyor get enough speed in the opposite direction to stop the forward momentum of the airplane? By focusing so much on the friction between the wheels and the conveyor, all you "Can't Flyers" are digging yourselves deeper into this hole....

The friction is something that needs to be taken out of this entire discussion, or it can open an entirely new can of worms because it wouldn't matter then....the belt's bearings would seize and burn up causing the conveyor belt to stop allowing the plane to take off wink

Quote:
Originally posted by BlueSky:
The plane would fly IF the belt was a constant speed less than the plane can attain or IF the belt did not speed up as power was applied to the aircraft's engines. In the scenario as presented, the aircraft's tires, mounted on their freewheeling, unpowered wheels, will merely rotate faster [b]in place as thrust is applied but the plane will not move forward.[/b]
You just stated it right here why the plane WOULD fly. The wheels can travel infinately faster than what the engines can produce. They only travel as fast as the plane is moving. HOWEVER, they can travel at 1000000000x faster than what the thrust can produce. so, it really doesn't matter how fast the conveyor is moving. The engines are still pulling the plane forward causing the wheels to just travel that much faster.

In this scenario, the wheels will travel as fast as the conveyor will make them, not as the engines will. That's because there are multiple forces at work here (GOD, I'm starting to sound like a broken record!!!) The forces applied between the conveyor belt and the wheels are comp[letely independant of the forces applied between the engine and the air!!!

Quote:
Originally posted by BlueSky:
Happy New Year!
Right back at ya!!!

Also, do me a favor. Do a Google search for "airplane on conveyor belt" 99% of the returned hits are going to chastise all the non believers because they are associating the airplane to a car because of the wheels. In just about all the hits, they will describe exactly what the "flyers" have been trying to describe to you guys....The conveyor is working on the wheels, not on the engines. [Wave]