What Myth would you want to see busted?

glacius, i think i can see why you think the helicopter will take off and we think it wont.

at a guess your helicopter is sat at the edge of the turntable. lets say the entire helicopter was rotating about its tail. if this was happening i'd be inclined to agree with you that the helicopter would take off

however, we are all talking about a helicopter being rotated about its drive-shaft to the blades. in this situation the helicopter would not be able to take off if the engine couldnt spin the blades faster than the helicopter was spinning, no matter how the engine was linked to the blades
 
Didn't one of our clever physics guys talk about this when we had this thread last time? He was either a physics or maths professor and he explained it. Does anyone else remember this?
 
No, again wrong. Helicopter is sat in the middle, so Centre of blades are lined up with centre of turntable.

Let's try again from a different angle.
Explain to me how the propshaft is being turned in the opposite direction and where and how these forces are being transferred to it.
 
He's in too deep to admit/consider that he's wrong and is making himself look rather stupid by trying to belittle those disagreeing with him.

I'm out.
 
The amount of fail in this thread is amazing.

Liampope said:
Glacus - with respect you're talking utter nonsense now. Your mocking tone doesn't help given the hole you're digging. Keep it simple - address this...
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Glaucus's mocking tone is fully justified because you're talking ****.

  • The helicopter will take off
  • The plane will take off
  • One sandwich cut in half produces two halves of one sandwich
 
Elixir said:
He's in too deep to admit/consider that he's wrong and is making himself look rather stupid by trying to belittle those disagreeing with him.

I'm out.
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And your not belittling either.

Come on simple question, how is turntable force transferred to propshaft. Please explain and show how.
 
Glaucus said:
Many people think a plane won't take of on a conveyer belt, just becuase they think it and they know it to be "true" doesn't make them correct.
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Yes well engine thrust has nothing to do with lift (else gliders wouldn't work ) lift is prdouced by air passing over the wings , no air over wings = no lift
 
Glaucus said:
On to helicopter. Turntable is linked to helicopter boady. Engine internals can still operate and connected to blades. No dirt link between forces. Blades can still spin.
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this is where you are wrong. let me use the car as an example, as it is exactly the same system for the purposes of the upcoming test (engine drives rotating thing.

test 1: you hold a car by its drive wheels. you rotate the car about this wheel 360 degrees while holding the wheel completely steady. the engine is connected to the car, the engine internals are connected to the wheel, therefor the engine will spin when the car rotation is done

test 2: you hold the blades steady and turn the body of the helicopter round 360 degrees. the engine is welded (or whatever) to the helicopter. the baldes are connected to the engine, so the engine internals WILL spin, just like the car engine span

hopefully you finally get this so we can put it to bed
 
My mind is melting... I can see the logic behind both sides. On the one hand, the explanation for planes on a treadmill applies here but on the other hand helicopter bodies are actually affected by the rotational force of the blades so they are not completely independent.

Blegh.
 
If the turntable is rotating anticlockwise and the rotors are spinning clockwise then it wont take of.

If the turntable and rotors are both spinning clockwise then it will take off.
 
Reaper 392 said:
test 1: you hold a car by its drive wheels. you rotate the car about this wheel 360 degrees while holding the wheel completely steady. the engine is connected to the car, the engine internals are connected to the wheel, therefor the engine will spin when the car rotation is done
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No that is not the same at all.
The wheels are directly linked to the internals of the engine.
The example would be you rotate the car body around the same axis as the propshaft, do the wheels turn, yes they would.

So get your examples correct.

Again tell me how the forces are transferred to the propshaft.
 
Voltjunkie said:
My mind is melting... I can see the logic behind both sides. On the one hand, the explanation for planes on a treadmill applies here but on the other hand helicopter bodies are actually affected by the rotational force of the blades so they are not completely independent.

Blegh.
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Just like a plane isn't totally removed from conveyor belt with its wheels. They're is still a small amount o force transferred from resistance. They however are not directly linked.
 
[FnG]magnolia;21281961 said:
And how do you think air over wings is achieved? Clue : engine thrust.
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NO speed relative to the air , the motive force is of no concequence if there is no movement.

In the scenario you would need a massive fan blowing air across the wings at a speed relative to the experiment. Then lift would be achieved as air would be flowing over the wings at the 'correct' speed.
 
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Glaucus said:
Just like a plane isn't totally removed from conveyor belt with its wheels. They're is still a small amount o force transferred from resistance. They however are not directly linked.
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Friction from wheel bearings isn't quite the same as the rotational force applied to a helicopter body though hence the possibly confusion :)
 
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