Manual page 62 :(

[norulz]

Rotfl

[Alien]

Instead, here’s a quick test to determine whether you should read this chapter.
If you’ve been on the internet in the past ten years, I’m sure you’ve heard this
riddle. There’s a plane on a magical threadmill runway. The threadmill defies
the laws of physics and can rotate as fast as the plane’s wheels while going
in the opposite direction. If the plane rolls forward at 10 mph, the runway
underneath rolls backwards at 10 mph. The plane’s wheels spin up to 200 mph
and the runway rolls back at 200 mph. The question is, will the plane move
forward and take off or remain stationary?
If you had to think about it for even a second, you need to read this chapter.
The answer of course is yes, the plane will take off as normal.

No, because plane flies when WIND is moving under and above WINGS. Wheels are just to protect propeller from the ground impact.

[BadAim]

It's a joke guys, it's just a joke.

[Letum]

ok...here is the confusion.....


If the conveyor is moving back at the same speed that the plane is moving forward, then the plane will take off as normal. (assuming the wheels can withstand 2x takeoff speed.)
The events look like this:

1) Throttle is applied
2) Plane moves foward
3) Conveyor moves at speed of plane
4) Wheels spin at twice the speed of the plane
5) Plane continues to accelerate and take off


If the conveyor is moving back at the same speed that the plane's wheels are moving forward, then a loops forms. The loop looks like this:

1) Throttle is applied
2) Wheels move forward
3) Conveyor moves at speed of wheels
4) As before, the wheels must move twice as fast as the conveyor for the plane to move forward, so the wheels speed up
5) Conveyor speeds up to speed of wheels
7) As before, the wheels must move twice as fast as the conveyor for the plane to move forward, so the wheels speed up
8 ) Conveyor speeds up to speed of wheels
9) As before, the wheels must move twice as fast as the conveyor for the plane to move forward, so the wheels speed up
10) Conveyor speeds up to speed of wheels

This theoretically continues until friction breaks the wheel bearings. This will happen instantly because the wheels will (theoretically) instantly try to achieve an infinite rate of spin.
This is happening because for a plane to move up a conveyor moving at 100mph, it's wheels must move at 200mph, but if the conveyor is matching the speed of the wheels, the wheels can never double the speed of the conveyor, but the wheels must travel at twice the speed of the conveyor for the plane to move forward. All the energy of the plane's forward thrust is used in the friction of the wheel bearings. Even with perfect, zero friction, bearings that don't burn out, you will just get infinite wheel spin speed.
That's hard to understand because we never see any kind of system like that in the real world. It's not possible.

The riddle should read:


"There’s a plane on a magical threadmill runway. The threadmill defies
the laws of physics and can rotate as fast as the plane [CUT] is moving
in the opposite direction. If the plane rolls forward at 10 mph, the runway
underneath rolls backwards at 10 mph. The plane [CUT] moves up to 200 mph
and the runway rolls back at 200 mph. The question is, will the plane move
forward and take off or remain stationary?
If you had to think about it for even a second, you need to read this chapter.
The answer of course is yes, the plane will take off as normal."

The problem is that this isn't much of a riddle as it tells us that the plane is moving at 200mph.

[Tomahawko]

"There’s a plane on a magical threadmill runway. The threadmill defies
the laws of physics and can rotate as fast as the plane [CUT] is moving
in the opposite direction. If the plane rolls forward at 10 mph, the runway
underneath rolls backwards at 10 mph. The plane’s wheels spin up to 200 mph
and the runway rolls back at 200 mph. The question is, will the plane move
forward and take off or remain stationary?
If you had to think about it for even a second, you need to read this chapter.
The answer of course is yes, the plane will take off as normal."

You still need to get away from "The plane's wheels spin up to 200 mph." Stick with "The plane move's forward 200 mph."
Theoretically speaking, I can make a wheel spin however fast I want. That doesn't mean the wheel itself is moving forward which is necessary when dealing with a plane. A plane needs the airflow under/over the wing to create lift. Without that it's hogwash.

[Letum]

Originally Posted by Tomahawko

You still need to get away from "The plane's wheels spin up to 200 mph." Stick with "The plane move's forward 200 mph."
Theoretically speaking, I can make a wheel spin however fast I want. That doesn't mean the wheel itself is moving forward which is necessary when dealing with a plane. A plane needs the airflow under/over the wing to create lift. Without that it's hogwash.

ed: yup, your right. My post will be edited.

[Tomahawko]

A better riddle would be:

If you put a magical frictionless plane in a wind tunnel where the plane moves neither forward or backward will it fly?

Something along those lines, as I didn't think through all the facets.

EDIT: Or skip the magic and attach a string.

[Letum]

Originally Posted by Tomahawko

If you put a magical frictionless plane in a wind tunnel where the plane moves neither forward or backward will it fly?
.

Haha! Concise!

[Space Communist]

ahaha That's awesome that they included that old chestnut. That problem has been argued about for years and years. I swear physics majors have written PH. D's on it. Anyway yes it will take of as normal if you assume the wheel's bearings are frictionless. If they are not frictionless it becomes more complicated, and becomes a balancing act between opposing forces. Even then it would likely take off unless the wheels seized from internal friction, since they would be rotating much faster than they normally would. I am no expert on landing gear design but i suspect they have a lot of lee-way.

[Tomahawko]

Instead, here’s a quick test to determine whether you should read this chapter.
If you’ve been on the internet in the past ten years, I’m sure you’ve heard this
riddle. There’s a plane on a magical threadmill runway. The threadmill defies
the laws of physics and can rotate as fast as the plane’s wheels while going
in the opposite direction. If the plane rolls forward at 10 mph, the runway
underneath rolls backwards at 10 mph. The plane’s wheels spin up to 200 mph
and the runway rolls back at 200 mph. The question is, will the plane move
forward and take off or remain stationary?
If you had to think about it for even a second, you need to read this chapter.
The answer of course is yes, the plane will take off as normal.

The reason it is so confusing is because they don't talk about the plane creating thrust. They only state that the wheels are spinning at 200mph and the 'magic' conveyor is moving in reverse at 200mph. In that sense the plane would stand still.

So they are INCORRECT. As far as I can tell.

If the wheels are spinning 400mph forward and the conveyor is moving in reverse at 200mph then the plane is moving forward at 200mph.

See the discrepancy?

The only way they can make the wheels and the conveyor spin at the same rate, while creating lift, would be if the entire conveyor system was maintaining lateral position with the plane.