re: Can this 747 take off?

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Just like how you completely ignored my questions to again tell me I just don't understand

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I'm sorry. What questions?


While we are at it, can you explain why this guy at 1;19ish is wrong about the interplay between the treadmill and the plane wheels?

Everybody is just talking past each other. meansonmy nailed it a few pages back. The hypothetical posed in the OP is flawed because in this make believe universe the plane cannot move forward if the wheels and belt are moving at the same speed in opposite directions unless the wheels are skidding.

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The hypothetical posed in the OP is flawed because in this make believe universe the plane cannot move forward if the wheels and belt are moving at the same speed in opposite directions unless the wheels are skidding.

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That's exactly right though.

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That's exactly right though.

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So in your mind, this magic conveyor belt has enough friction to overcome the thrust generated by a 747.

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Fantastic response.

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Oh I'm sorry, should I have asked "what questions" even though they are right there on your screen?

You keep mentioning the power of the plane. It isn’t relevant. It could be a hobby plane. Or a Cessna 152.

The treadmill is magic as it and the wheels are synced.

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this magic conveyor belt has enough friction to overcome the thrust generated by a 747

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Wow dude. I really didn't know your lack of understanding was this deep. Here's a succinct reply that reflects what's going on here:

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Many people are looking at this wrong. They seem to not consider that for the entire time of the "experiment", the full weight of the plane is supported by the wheels which remain in contact with the ground (the conveyor belt).

In the In the first scenario, as soon as the plane moves any amount forward, the conveyor belt moves the plane back to the starting point. It doesn't matter how the plane is propelled forward, as soon as the plane tries to move any amount forward, the conveyor belt moves the plane back to the starting point.

There is no "faster and faster till infinity" issue. The plane is not moving relative to the objects around it. The wheels will spin faster and faster (rpms) until the plane is at full throttle at which time the speed of the wheels will level off to a "constant" speed.

The speed of the plane relative to the objects around it, and relative to the air around the plane, and relative to the Earth, would be 0. It would never have a chance to overcome inertia.

The most important thing a plane needs in order to fly, is lift. In order to generate and sustain the amount of lift required, a minimum airspeed is necessary. With the plane at rest, it will never achieve the lift necessary for flight.

In the second scenario, well it seems a little bit contrived, but yes. As soon as the speed of the plane relative to the objects around it, and relative to the air around the plane, and relative to the Earth reaches sufficient airspeed, the plane will fly, as it normally does.

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The treadmill is magic as it and the wheels are synced.
And the thrust will over come it

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How? The axles of the wheels cannot move forward if the wheels are being counteracted by the treadmill. You realize the treadmill is moving, right?

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n the In the first scenario, as soon as the plane moves any amount forward, the conveyor belt moves the plane back to the starting point. It doesn't matter how the plane is propelled forward, as soon as the plane tries to move any amount forward, the conveyor belt moves the plane back to the starting point.

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How can this happen though? The wheels are not what moves the plane forward or backward.

The plane starts out with zero thrust, zero forward velocity, zero wheel rotation, zero treadmill rotation.

The wheels do not turn, and the jet will propel the treadmill track forward, while the wheels remain at zero rotation, and then it will get fast enough to take off in the conventional sense of hydrodynamic lift