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Accelerated Evolution

Physics Challenge!


Crube

  

8 members have voted

  1. 1. Will it take off?

    • Yes
      2
    • No
      6


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A helicopter is resting on a turntable that rotates the helicopter in the opposite direction to which the rotor blades are turning, at the same speed. Say that the helicopter is made of sturdier material and the risk of it just being shredded up from the velocity is out of the equation. Can the helicopter take off?

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^Pretty much. The are multiple instances in which the helicopter could take off with the limited information Crube gave. Only one of which would allow the pilot any noteworthy chance of both succeeding in staying airborn and living through the experience.

If anyone cares; Helicopter needs wheels and not skids and needs to be on the trailing edge of the turn table and facing the center.

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Yeah, I wasn't really thinking when I made this thread. I was sort of cooking at the same time, hah! But yes, understand that the structure of the heli is strong enough to withstand the velocity made and the pilot is in one of those protective roll cage something similar to a stock car. The heli is on the turntable where the centre of balance would be on the heli itself. No wind and it's a clear day.

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Is there any affect with the tail rotor?

Would worsen things. The tail rotor generates very little vertical lift, and unlike the main rotor assembly, is not built in such a way as to be flexible, and operates at a much, much higher RPM. Its main function is also to keep the helicopter straight, which in this case would mean acting directly against centrifugal forces. Utilizing the tail rotor would probably tear the helicopter right apart.

Although, I'm not totally sure what would happen if you pitched the tail rotor into the rotation of the turn table. I assume it would just flip the helicopter.

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Don't think so. In most modern day helicopters the tail rotor is just there to keep the helicopter straight and most of the turning is handled by actually pitching the main rotor - meaning they've become smaller and less powerful. In older designs the tail rotors were more powerful because they were entirely responsible for turning the vehicle... which I think would just cause to much stress on the helicopter itself. Although, again if it pitched into the turn I think it would change the relative air speed enough to liftoff, but the helicopter would tip almost right away from the huge windsheer.

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Yes, because regardless of if a force is counteracting the mechanics of the helicopter it still creates wind resistance thus creating lift. Same thing with the plane on the treadmill. It's still move, still creating resistance, still bearing lift.

not necessarilly, if the turntable is moving in the opposite direction of the rotor blades at the exact same speed it's counteracting the rotating motion of the blades. The plane on the other hand, has to be moving in a forward motion for the plane to take off, given the way planes work. The air has to be moving over and under the wings to create the lift necessary for the aircraft to take off. If the aircraft is on a treadmill, it is not moving forward in space.

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Same thing with the plane on the treadmill. It's still move, still creating resistance, still bearing lift.

Off topic, but just because Mythbusters "busted" the myth on the whole airplane/treadmill thing doesn't necessarily mean anything. If the treadmill was going the exact speed the plane will go, then that's all the airplane will do: just move in one place. If I remember correctly, one of the conditions for the treadmill problem is that there was zero wind movement at all.

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Off topic, but just because Mythbusters "busted" the myth on the whole airplane/treadmill thing doesn't necessarily mean anything. If the treadmill was going the exact speed the plane will go, then that's all the airplane will do: just move in one place. If I remember correctly, one of the conditions for the treadmill problem is that there was zero wind movement at all.

Actually that's not true. Plane wheels are free floating and the treadmill provides no more resistance then the normal ground. Since the propulsion system is what moves the plane forward and not the wheels the treadmill does nothing. The plane would need to be in an airless vacuum not to move.

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Actually that's not true. Plane wheels are free floating and the treadmill provides no more resistance then the normal ground. Since the propulsion system is what moves the plane forward and not the wheels the treadmill does nothing. The plane would need to be in an airless vacuum not to move.

the difference is that the plane itself is not moving in space. it is staying in the same spot, regardless of if the wheels are moving. The air isnt moving over the wings, which is what makes the plane lift off. if there is no lift there is no flight

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the difference is that the plane itself is not moving in space. it is staying in the same spot, regardless of if the wheels are moving. The air isnt moving over the wings, which is what makes the plane lift off. if there is no lift there is no flight

Yes, I suppose what I'm trying to say is I'm pretty certain the plane one is an impossible scenario. It can only exist as a thought experiment, because no matter what you do the treadmill in reality isn't going to have enough traction to deny the plane movement and thus, lift. So in the real world the plane takes off, in magic happy secret perfect math world, it doesn't.

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So in the real world the plane takes off, in magic happy secret perfect math world, it doesn't.

STOP TAINTING MY MAGIC HAPPY SECRET PERFECT MATH WORLD!!!

On topic: I don't think the heli would be able to take off. The problem isn't the fact that the turntable is negating the rotor's torque. The problem is that the body of the helicopter is rotating on the turntable, such that the body itself is acting like a big propeller, the rotational force of which (the torque) would negate the primary rotor, as there is more force (more mass and same acceleration/velocity) than the main rotor can counteract.

If we presumed the helicopter was a MAGIC HAPPY SECRET PERFECT MATH helicopter with 0 mass, with only a rotor, that is what would render the above irrelevant, and the helicopter would lift, as there's only a propeller XD.

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I'm pretty sure zero lift would be generated, but I guess I'm not a physicist.

if the heli was dead center on the turn table so the body of the chopper was rotating at the same speed of the rotors no lift would be generated. Same with the plane on the treadmill. the wings themselves arent moving forward, which wouldnt allow air to flow over them, thus not generating lift.

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