Donut62
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Then what are you still arguing about? The thrust moves the plane through the air. The conveyor belt moves the ground. Neither are related.
Plane on conveyor belt
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Then what are you still arguing about? The thrust moves the plane through the air. The conveyor belt moves the ground. Neither are related.
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Irrelevant because you fail at reading comprehension, hombre.
"The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation." This language leads to a paradox: If the plane moves forward at 5 MPH, then its wheels will do likewise, and the treadmill will go 5 MPH backward. But if the treadmill is going 5 MPH backward, then the wheels are really turning 10 MPH forward. But if the wheels are going 10 MPH forward . . . Soon the foolish have persuaded themselves that the treadmill must operate at infinite speed. Nonsense. The question thus stated asks the impossible -- simply put, that A = A + 5 -- and so cannot be framed in this way. Everything clear now?
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You fail again.
The belt negates forward speed.
If theres no forward speed, no lift can be generated.
Do you get it yet?
Donut62
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It....doesn't....matter.....what......the......wheels........do.....what matters......is the speed of the plane's fuselage.....which is in......relation.....to the air.....not the ground. The wheels are free spinning. They don't do shit. They sit there. How do planes on ski's take off!!!! There are no wheels!!!!!
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LOL ok ... you.. wanna...use ...dots....the ...plane...relative...to...the...air..is...stationary...because....forward...motion
....is...negated....NEGATED...by...the......belt........the...planes...speed...relative..to...the..surrounding
....air...mass....is...the.....key...and...it....reamins....zero....as...long..as...the...belt...spins....against
....the..wheels
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By that example, if the plane were on skis, and we moved the belt against the skis so the plane stayed still, it would not lift off.
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http://forum.physorg.com/index.php?showtopic=2417&st=0
heres a 600 page argument on a physics forum about it
heres a 600 page argument on a physics forum about it
If the treadmill speed is dynamic, always matching the speed of the wheels, the plane will still move forward. The only problem is that by the end of the runway the wheels will be spinning extremely fast and almost ready to / possibly already fallen off. The spin of the wheels has nothing to do with the plane, though. The wheels are essentially suspended in a bearing. They will continue to spin at infinite speed until the bearing breaks, the wheel speed stops increasing (impossible with this hypothetically indestructable treadmill), or the plane takes off.
I agree that you are right in the question asking the impossible. I believe the original theory doesn't involve a treadmill that dynamically changes, though. Simply matches the hypothetical speed of the plane and pulls in the opposite direction.
The friction in the bearings would probably break the wheels instantly. Then the plane would basically "catch" on the moving sphere and its nose would probably smack into the ground, from all the air moving over the wings and pushing the plane forward.
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We're discussing this in a hypothetical sort of way- we're not factoring wheel bearing failure, etc.
If the wheels move 1 mph, and the belt counteracts this by going 1 mph the other way, the planes pilot guns the engines, and the belt speeds up too, keeping the plane still. If the engines are max thrust, everytime the plane moves forward a fraction of a mph, the belt speeds up to negate it. The top speed of a 747 is ~600mph. If it were full throttle on the ground, trying to move 600mph, and the belt is moving 600 the other way, the plane stays still. If the belt does 601, the plane moves backward. If the belt does 599, the plane moves forward.
If you are assuming indestructable treadmill and bearings there is no reason to have the treadmill speed increase exponentially. Simply having the speed of the treadmill match the initial speed of the wheels would yield the same difference in speed. In which case the plane would take off.
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If the belt matches the speed of the wheels, how does the plane move forward? The belt is negating the forward motion of the plane.
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Here's another scenario to thicken the plot (shit).
You have a high powered jet aircraft. The engine packs more horsepower than the entire starting lineup of the Daytona 500. The brakes are set and the aircraft is throttled up to max power. Will the plane lift off?
Before you answer, the question that started this thread was a bullshit question. If you advance the throttle of a stationary airplane, the plane moves forward and the wheels turn. If you advance the throttle further, the plane moves forward at a faster rate and the wheels spin at a faster rate. Therefore, the faster the plane taxis the faster the wheels spin (until take off).
The original question was thus:
Under the highlighted circumstances, the plane ain't goin up. Under the circumstances used by Mythbusters, maybe...but you have to realize that Ultralights only need about 40 feet to take off. But with absolutely zero forward progress relative to the outside air (wind is certainly a factor). The plane stays grounded. The two things (besides thrust) that effect an aircraft's ability to leave the ground are weight and wing surface.
An F-4 phantom is a flying fuckin brick. It's heavy and it has very little wing surface. It needs a shit load of runway to get off the ground. A U-2 is relatively light and has a shitload of wing surface. It doesn't need much runway to get airborne.
Now back to my scenario. As an aircraft mechanic, I've been in and worked on several different aircraft. As any aircraft mechanic will tell you, "maintenance" runs are commonplace. Meaning that after you change a propeller or a hot section of a turbine engine, you have to make sure the fucker still runs. To do this, you taxi the plane out to the trim pad and you run the aircraft real hard with your feet stomping on the brakes. I've done this in propeller driven aircraft, turbo-props and jet engines with enough ponies to raise the titanic and NEVER have I accidentally left the runway.
You have a high powered jet aircraft. The engine packs more horsepower than the entire starting lineup of the Daytona 500. The brakes are set and the aircraft is throttled up to max power. Will the plane lift off?
Before you answer, the question that started this thread was a bullshit question. If you advance the throttle of a stationary airplane, the plane moves forward and the wheels turn. If you advance the throttle further, the plane moves forward at a faster rate and the wheels spin at a faster rate. Therefore, the faster the plane taxis the faster the wheels spin (until take off).
The original question was thus:
Under the highlighted circumstances, the plane ain't goin up. Under the circumstances used by Mythbusters, maybe...but you have to realize that Ultralights only need about 40 feet to take off. But with absolutely zero forward progress relative to the outside air (wind is certainly a factor). The plane stays grounded. The two things (besides thrust) that effect an aircraft's ability to leave the ground are weight and wing surface.
An F-4 phantom is a flying fuckin brick. It's heavy and it has very little wing surface. It needs a shit load of runway to get off the ground. A U-2 is relatively light and has a shitload of wing surface. It doesn't need much runway to get airborne.
Now back to my scenario. As an aircraft mechanic, I've been in and worked on several different aircraft. As any aircraft mechanic will tell you, "maintenance" runs are commonplace. Meaning that after you change a propeller or a hot section of a turbine engine, you have to make sure the fucker still runs. To do this, you taxi the plane out to the trim pad and you run the aircraft real hard with your feet stomping on the brakes. I've done this in propeller driven aircraft, turbo-props and jet engines with enough ponies to raise the titanic and NEVER have I accidentally left the runway.
The wheels spin freely. If the treadmill pulls the wheels, the wheels aren't technically attached to the plane. They sit in a bearing that allows them to spin. Either the bearing breaks, which isn't the case, since it is indestructable, or the plane essentially is a hovercraft, with the wheels spinning freely. Imagine a car elevated on a car lift. You sit in the car and turn it on and press the gas. The wheels begin to spin, but the car doesn't move.
Good to know.
I assumed it would be a sphere rotating on earth. Obviously if you're talking about the earth itself, there is no gravitational force around it to pull the plane off balance causing it to go headfirst. If there is a sphere on the surface of earth spinning, the gravity of the earth will make the plane become off-balance.
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