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Thread: Okay Krupski or other knowing people answer this please

  1. #41
    Administrator Krupski's Avatar

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    Quote Originally Posted by N/A View Post
    Put some roller skates on, get on a treadmill and see what happens.


    I think the confusion here is this: Is the airplane which is sitting on the "treadmill" just parked, or are the engines running at takeoff thrust?

  2. #42
    Administrator Krupski's Avatar

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    Quote Originally Posted by imanaknut View Post
    Yes, forward thrust of the engines is countered by the treadmill running against forward motion. The plane will never fly because no airflow is generated over the wings.

    Like a person running on a treadmill, you never move forward because the treadmill speed, which in this case you control, is moving in the opposite direction keeping you stationary.
    You are completely wrong. ASSUMING that the airplane wheels are free spinning (i.e. brakes not on), and assuming that the treadmill matches the wheel rotation speed, all that will happen is this:

    (1) The wheels will be stationary.

    (2) The airplane will take off and fly normally.

  3. #43
    Team Guns Network Silver 04/2013 alismith's Avatar

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    Quote Originally Posted by Krupski View Post
    Does not matter.

    If the airplane has takeoff thrust, and it's sitting on a treadmill that matches the wheel speed so that they don't turn, all you're doing is removing the minuscule drag of the wheel bearings and the airplane takes off even easier.

    Remember, the wheels have ABSOLUTELY NOTHING to do with how the airplane flies. It's all airflow over the wings, caused by the engine thrust pushing the airplane forward into the air.
    The plane remains stationary, even when thrust is provided. If the plane remains stationary, there is no airflow around the wings.

    Even if the plane accelerates, the treadmill will still match the speed of the wheels as the thrust tries to move the plane forward thereby canceling out any forward moving, causing the plane to stay where it is on the treadmill. Since the plane remains stationary in relation to the ground around the treadmill, it can't get any airflow around the wings, therefore it can't take off or fly.

    The purpose of the treadmill is to negate any forward movement of the plane. If you apply thrust to the plane, the wheels have to move in response, but no matter what speed the wheels move, the treadmill moves just as fast in the opposite direction, thereby preventing any forward movement of the plane.

    The treadmill generates no airflow....it just cancels out any forward movement of the plane; therefore, with no forward movement, the plane's wings get no moving air, and lift isn't provided. No lift-no flight.
    Last edited by alismith; 08-29-2019 at 11:28 AM.
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  4. #44
    Team Guns Network Silver 04/2013 alismith's Avatar

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    Quote Originally Posted by Krupski View Post
    You are completely wrong. ASSUMING that the airplane wheels are free spinning (i.e. brakes not on), and assuming that the treadmill matches the wheel rotation speed, all that will happen is this:

    (1) The wheels will be stationary.
    If the wheels are stationary, so is the plane. The treadmill matches the speed of the wheels. If you apply thrust, the wheels turn faster. If the wheels spin faster, the treadmill moves faster, in the opposite direction, to match the speed of the wheels. Thus, the wheels may be moving faster, but so is the treadmill now. The plane still remains stationary no matter how much thrust is provided.

    While the wheels don't help the plane fly, they do help it, by moving faster in relation to the thrust provided, reach the speed the plane needs to generate enough air movement to create the lift required to make it fly. That's why they use wheels instead of steel blocks that contact the runway. Wheels turn, steel blocks don't.

    Quote Originally Posted by Krupski View Post
    (2) The airplane will take off and fly normally.
    Only if the plane is moving fast enough for lift to be generated, On a treadmill, such as the one discussed in the OP, the plane doesn't move and can't fly. No lift.....
    Last edited by alismith; 08-29-2019 at 01:28 PM.
    "Valar morghulis; valar dohaeris."

    "Never say, "gun control" but instead say, "victim disarmament." - L Neil Smith

    Making good people helpless won't make bad people harmless.

    Freedom isn't free.

    "Attitude is the paintbrush that colors our world." TV Series, Haven.

    My Spirit Animal has rabies.

  5. #45
    Senior Member NAPOTS's Avatar

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    I think you guys are missing the point that the wheels don't provide thrust to the airplane. This would work on a treadmill with a car but only at steady state. Airplane gets is thrust from the engines so it would move forward as if nothing was going on at the treadmill

  6. #46
    Team Guns Network Silver 04/2013 alismith's Avatar

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    Quote Originally Posted by NAPOTS View Post
    I think you guys are missing the point that the wheels don't provide thrust to the airplane. This would work on a treadmill with a car but only at steady state. Airplane gets is thrust from the engines so it would move forward as if nothing was going on at the treadmill
    How does the plane move forward if the wheels don't move faster in response to the thrust? If this were true, then the wheels aren't needed at all.

    In your car example; if the treadmill moves in response to the car's wheels, then when you try to accelerate the car, the wheels will spin faster and so will the treadmill. Don't forget that gravity keeps the wheels in contact with the treadmill.

    A plane can't take off unless the wheels help it reach the speed it needs for air to build up enough negative pressure over the wings to give it lift.

    The wheels are an important part of allowing the plane to reach the speed it needs to take off, otherwise, steel blocks would by just as effective and aircraft carriers wouldn't need any type of runway or catapult. The plane would just launch itself once it attains flight speed. (Landing would be a little trickier, though.)

    Don't forget that the treadmill moves at the same speed, in opposite the direction the wheels are spinning, no matter how much thrust you provide. A plane can't take off unless the wings are moving in relation to the air around them. The treadmill prevents the plane from moving at all. If you were beside the plane, no matter how fast the engines are revving and thrusting, the plane is stationary. The wheels have to be moving forward over the surface on which they're moving in order for the plane's wings to get lift. The treadmill prevents the wheels from acting this way. The treadmill prevents any forward movement of the plane, thereby preventing the wings from gaining lift.

    The plane won't take off. It'll just stay in the same place even with its engines running at full throttle.
    Last edited by alismith; 08-29-2019 at 10:44 PM.
    "Valar morghulis; valar dohaeris."

    "Never say, "gun control" but instead say, "victim disarmament." - L Neil Smith

    Making good people helpless won't make bad people harmless.

    Freedom isn't free.

    "Attitude is the paintbrush that colors our world." TV Series, Haven.

    My Spirit Animal has rabies.

  7. #47
    Team GunsNet Silver 12/2011 N/A's Avatar

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    I'll just leave this here.

    https://youtu.be/YORCk1BN7QY
    No enemy of America would have ever been killed if they didn't show up to be killed. HDR

  8. #48
    Senior Member NAPOTS's Avatar

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    Quote Originally Posted by alismith View Post
    How does the plane move forward if the wheels don't move faster in response to the thrust? If this were true, then the wheels aren't needed at all.
    .
    Same way it takes off on a runway that isn't moving at all except the wheels are rotating twice as fast
    Last edited by NAPOTS; 08-29-2019 at 11:11 PM.

  9. #49
    Senior Member NAPOTS's Avatar

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    Quote Originally Posted by NAPOTS View Post
    Same way it takes off on a runway that isn't moving at all except the wheels are rotating twice as fast
    Engine will need to provide a small amount of additional thrust to counter act the additional friction in the axle and rolling resistance due to the greater rotational velocity of the wheels but my guess this is minimal compared to the drag experienced at the speed required for enough lift to takeoff

  10. #50
    Team Guns Network Silver 04/2013 alismith's Avatar

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    Quote Originally Posted by NAPOTS View Post
    Same way it takes off on a runway that isn't moving at all except the wheels are rotating twice as fast
    If the wheels are moving twice as fast, then the treadmill has to be moving twice as fast, too. Remember, the treadmill matches the wheels speed. The wheels are spinning, but the plane isn't moving forward at all. If the plane doesn't move, there is no lift generated on the wings.
    "Valar morghulis; valar dohaeris."

    "Never say, "gun control" but instead say, "victim disarmament." - L Neil Smith

    Making good people helpless won't make bad people harmless.

    Freedom isn't free.

    "Attitude is the paintbrush that colors our world." TV Series, Haven.

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  11. #51
    Team Guns Network Silver 04/2013 alismith's Avatar

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    Quote Originally Posted by N/A View Post
    I'll just leave this here.

    https://youtu.be/YORCk1BN7QY
    There is so much wrong with the way they conducted this "experiment." The countering speeds didn't match each other and the plane's wheels were moving faster than the sheet under the wings.

    There was no "control" in this "experiment." This video can't be used to prove the point you're trying to prove.
    "Valar morghulis; valar dohaeris."

    "Never say, "gun control" but instead say, "victim disarmament." - L Neil Smith

    Making good people helpless won't make bad people harmless.

    Freedom isn't free.

    "Attitude is the paintbrush that colors our world." TV Series, Haven.

    My Spirit Animal has rabies.

  12. #52
    Team Guns Network Silver 04/2013 alismith's Avatar

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    Quote Originally Posted by alismith View Post
    How does the plane move forward if the wheels don't move faster in response to the thrust? If this were true, then the wheels aren't needed at all.
    Perhaps I should have stated that the wheels may spin faster due to the engine's thrust, but the treadmill,also, moves faster in response to the wheels moving faster.

    If the plane's thrust equals enough to push the plane 200 mph., then on a regular runway, the plane moves at 200 mph. because the wheels allow the plane to move at the speed.

    But, if the plane's wheels are moving 200 mph. forward and the treadmill beneath the wheels is moving at 200 mph. backward, this negates any forward movement of the plane itself.

    If 200 mph. forward is countered with 200 mph. backward, then the result of movement on the plane is 0 mph, right?

    In the video posted by N/A, the plane's wheels overcame the backward movement of the "treadmill" and allowed the plane to move forward.

    Since the wheels and treadmill speeds cancel each other out, there can be no forward movement of the plane. All the thrust does (while on the runway) is get the wheels moving fast enough to move it through the air that provides lift.

    So, if the plane can't move forward, because the wheel speed is 0 mph., then there is no air moving around the wings. No air moving around the wings means no lift. No lift; no flight.

    The engine(s) only provide forward movement. They don't provide any lift at all. The wings provide the lift.
    Last edited by alismith; 08-30-2019 at 12:01 AM.
    "Valar morghulis; valar dohaeris."

    "Never say, "gun control" but instead say, "victim disarmament." - L Neil Smith

    Making good people helpless won't make bad people harmless.

    Freedom isn't free.

    "Attitude is the paintbrush that colors our world." TV Series, Haven.

    My Spirit Animal has rabies.

  13. #53
    Senior Member NAPOTS's Avatar

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    Quote Originally Posted by alismith View Post
    Perhaps I should have stated that the wheels may spin faster due to the engine's thrust, but the treadmill,also, moves faster in response to the wheels moving faster.

    If the plane's thrust equals enough to push the plane 200 mph., then on a regular runway, the plane moves at 200 mph. because the wheels allow the plane to move at the speed.

    But, if the plane's wheels are moving 200 mph. forward and the treadmill beneath the wheels is moving at 200 mph. backward, this negates any forward movement of the plane itself.

    If 200 mph. forward is countered with 200 mph. backward, then the result of movement on the plane is 0 mph, right?

    In the video posted by N/A, the plane's wheels overcame the backward movement of the "treadmill" and allowed the plane to move forward.

    Since the wheels and treadmill speeds cancel each other out, there can be no forward movement of the plane. All the thrust does (while on the runway) is get the wheels moving fast enough to move it through the air that provides lift.

    So, if the plane can't move forward, because the wheel speed is 0 mph., then there is no air moving around the wings. No air moving around the wings means no lift. No lift; no flight.

    The engine(s) only provide forward movement. They don't provide any lift at all. The wings provide the lift.
    I assume you want rolling without slipping. In this case the speed of the wheel at the point of contact always matches the speed of what it is rolling on in the case of the ground it is 0, it is the translational velocity of the object at the center of rotation or the axle and twice that at the top. It is not possible for the ground, treadmill, roller or anything else to be moving at the translational velocity of the center of rotation without slipping. Also is this case, assuming the brakes are free you only have friction transmitting torque between the wheel and axle. The wheels don't drive the plane down the runway as much as the runway or treadmill can't drive the plane and stop it from moving. Interesting point if you were standing still on this rtreadmill you'd observe the plane move away from you twice as fast as normal but an observer on the ground wouldn't
    Last edited by NAPOTS; 08-30-2019 at 12:20 AM.

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    Quote Originally Posted by alismith View Post
    There is so much wrong with the way they conducted this "experiment." The countering speeds didn't match each other and the plane's wheels were moving faster than the sheet under the wings.

    There was no "control" in this "experiment." This video can't be used to prove the point you're trying to prove.
    That's what I got out of it, and it isn't on a treadmill, You can clearly see the planes tires are still on the ground due to the weight over the plastic sheet they are trying to simulate a treadmill. Totally bogus. This is what my cousin bases his argument from, this completely unscientific from every angle experiment.

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    Team GunsNet Silver 12/2011 N/A's Avatar

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    I think we can sum up this discussion nicely.

    No enemy of America would have ever been killed if they didn't show up to be killed. HDR

  17. #57
    Team GunsNet Silver 12/2011 N/A's Avatar

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    Quote Originally Posted by 1 Patriot-of-many View Post
    That's what I got out of it, and it isn't on a treadmill, You can clearly see the planes tires are still on the ground due to the weight over the plastic sheet they are trying to simulate a treadmill. Totally bogus. This is what my cousin bases his argument from, this completely unscientific from every angle experiment.
    So, lets get this straight, because the tarp or whatever ran over the ground (a solid stationary surface), the plane was able to take off because the weight of the plane actually put the tire in contact with the ground(solid, stationary surface)?

    So, how is a treadmill built? It is nothing but a continuous belt that run over a stationary solid surface board underneath the belt.
    Put the plane on a treadmill and the weight of the plane will cause the wheels to push the belt down and then the wheels will be in contact with the underlying board.
    The only thin that moves is the belt, the rest of the system remains stationary. As the board remains stationary, the same as the ground, the plane will move forward when forwars force(thrust) is applied.
    No enemy of America would have ever been killed if they didn't show up to be killed. HDR

  18. #58
    Administrator Krupski's Avatar

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    Quote Originally Posted by N/A View Post
    I think we can sum up this discussion nicely.

    I wonder how many lurkers are rolling with laughter at the abysmal level of basic physics knowledge being displayed by some?

    "Better to remain silent and appear ignorant than to speak out and remove all doubt".

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    Team GunsNet Silver 12/2011 N/A's Avatar

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    Quote Originally Posted by Krupski View Post
    I wonder how many lurkers are rolling with laughter at the abysmal level of basic physics knowledge being displayed by some?

    "Better to remain silent and appear ignorant than to speak out and remove all doubt".
    Well, I have to admit I probably have a bare basics of physics knowledge, and have my own disagreements with parts of relativity.

    That being said, I would not be a good teacher because I just state what I think is obvious and expect others to see that obviousness. I guess I get frustrated when I can't seem to get a point across.
    No enemy of America would have ever been killed if they didn't show up to be killed. HDR

  20. #60
    Team Guns Network Silver 04/2013 alismith's Avatar

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    Quote Originally Posted by Krupski View Post
    I wonder how many lurkers are rolling with laughter at the abysmal level of basic physics knowledge being displayed by some?

    "Better to remain silent and appear ignorant than to speak out and remove all doubt".
    Okay. Correct me if I'm wrong and tell me where I went wrong.

    On a normal takeoff, from a runway, the plane is standing at one end of the runway. It applies thrust and the wheels move it forward down the runway. Once the speed is correct (sufficient lift applied to the wings), the plane takes off and the wheels are no longer needed.

    The wheels are only needed to move the plane down the runway. The thrust moves the plane forward in the air and pressure differences build up on the wings (creating lift). Once the correct speed is obtained, the plane lifts up and flies.

    Now, the plane MUST move forward to create the lift on the wings. If the plane doesn't move forward, no lift is created and the plane can't fly.

    Now to the treadmill.

    According to the OP, the treadmill is all the plane has underneath it (the wheels are in contact with the treadmill).

    The treadmill is designed to instantly match the exact speed of the wheels, but it moves in the opposite direction the wheels are spinning. Once the wheels start to move due to applied thrust, the treadmill starts to move at the same instant and in the opposite direction.

    If the only contacts are the wheels and the treadmill, and they are both moving in opposite directions to each other, the plane remains stationary, right?

    If it remains stationary, no air is moving over the wings, and no lift is created.

    What am I missing?
    "Valar morghulis; valar dohaeris."

    "Never say, "gun control" but instead say, "victim disarmament." - L Neil Smith

    Making good people helpless won't make bad people harmless.

    Freedom isn't free.

    "Attitude is the paintbrush that colors our world." TV Series, Haven.

    My Spirit Animal has rabies.

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