What Myth would you want to see busted?
- Thread starter Linkex
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Depends on the wording of the thought experiment, though (which I haven't bothered looking for). If the thought experiment is worded making it clear you are supposed to consider that the blades are rotating at their normal speed wrt the helicoptor, and the whole helicoptor is on a turntable spinning at the same angular velocity the other way, then by definition the blades are stationary. Bringing too much real physics/engineering into these often misses what was originally supposed to be a simple point, imho
. Like the plane on a conveyor belt one. Normally, though, they are not worded clearly enough and the whole configuration of the system is up for debate, again, like that plane on a conveyor belt one, so you can have endless forum threads of argument about them . I suspect the same could be said of this helicoptor one. Let's not have an endless argument though .
That's not what's being talked about. If you spin the blades up like normal and rotate the body of the helicopter at the same speed as the blades but in opposite direction. What happens. The blades will not be stationery.
Why does rotating helicopter suddenly stop the blades rotating. It doesn't at all. It's a lack of logic in your thinking. Just like people who think a plane on a conveyor belt won't take off.
Why does rotating helicopter suddenly stop the blades rotating. It doesn't at all. It's a lack of logic in your thinking. Just like people who think a plane on a conveyor belt won't take off.
Totally wrong, they would not be stationery compared to the air. To much lack of logic,
The earth is round.
Because it's obviously flat else everyone at the equator would just fall of into space and the Southern Hemisphere would be unihabitable.
People don't fall of at the Equator, people live in the Southern Hemishpere therefore world is really Flat
QED
Because it's obviously flat else everyone at the equator would just fall of into space and the Southern Hemisphere would be unihabitable.
People don't fall of at the Equator, people live in the Southern Hemishpere therefore world is really Flat
QED
This has already been busted as a myth. 30,000 scientists in America have banded together to sue Al Gore over his global warming lies. Also the UN was caught fudging data over gobal warming.
Soldato
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They've already busted the "myth" that the moon landings are fake.
Busted! (Just highlights it)
you can edit titles but only within a few minutes.
Yes they would - I can't explain to you why because I can't figure out which bit of basic logic you are missing.
Also, your example is incorrect - sure, it wouldn't snap to stationary instantly because of its own momentum, but it would slow down to stationary as the moentum gave out to air friction.
Just lol. The gas turbine will be turning. Independent of what the body of the hellicopter is doing. The engine will be powering the blades that will be spinning. The body will also be spinning in opposite direction. thus the bearing will be experience double speed.
My logic is fine, yours is very much broken.
Ah but you're doing what I described - trying to 'pollute' what was probably supposed to be a very simple thought experiment with too much real physics/engineering.
So you're bringing in some knowledge of how a real turboshaft engine works and stating like it's a fact that the blades would still rotate at the normal speed wrt the ground because they are only slowed by air resistance. But really? Let's add more 'real' detail - could the air intake and fueling systems really work while they are spinning attached to the helicoptor at the same speed as the rotor blades - probably not. And the helicoptor would have almost certainly flown to pieces long before you reached that situation anyway. See - you already broke the nice simple thought experiment with the first layer of 'trying to take it too seriously' See what I mean?Also the plane on the conveyor belt can logically be argued to not be able to take off depending on the wording of the question. All that would take, impossible materials/engineering notwithstanding, is the conveyor belt running so fast that there is enough friction in the tyres and wheel bearings to entirely cancel the thrust of the engines so it doesn't go anywhere.
Anyway - good thread hijack
It's a myth not a simple thought experiment at no way even with simple thought would it stop rotating the blades. That assumption is wrong on all levels.
I've allready talked about fuel system etc. Those are the unkiwenables. Along with craft stability. Not if the forces will cancel each other out. Because they simply don't. Even stripping it down to very basics. The forces do not cancel each other out.
It's not a thread hijack and a plane on a conveyor belt can not be argued logically that it would not take off.
I've allready talked about fuel system etc. Those are the unkiwenables. Along with craft stability. Not if the forces will cancel each other out. Because they simply don't. Even stripping it down to very basics. The forces do not cancel each other out.
It's not a thread hijack and a plane on a conveyor belt can not be argued logically that it would not take off.
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It certainly can - like I said - if the conveyor belt moves fast enough there can be so much drag from the rolling resistance of the tyres on the belt and from friction in the wheel bearings that the thrust of the engines is cancelled. All used up overcoming tremendous drag. But that is to miss the point of the thought experiment/myth (no real difference). The simple and intended solution is of course that the plane takes off with it's wheels going a bit faster than normal.
The theory is your blade is attched to 2 platforms ( body of copter and turntable )
We will assume clockwise rotation as 'positive', and speed of 100 RPMs for both platforms
So
platform 1 spins blades clockwise so +100 RPM to blades
platform 2 spins blades anti clockwise so -100 RPM to blades
Therefor overall blade movement relative to the ground = 0
Also plane on conveyer belt will not take of becuse of the same mechanics (only using straight line rather than radial speed)
If your plane is static no air is forced over the wings therefore no lift is produced.
We will assume clockwise rotation as 'positive', and speed of 100 RPMs for both platforms
So
platform 1 spins blades clockwise so +100 RPM to blades
platform 2 spins blades anti clockwise so -100 RPM to blades
Therefor overall blade movement relative to the ground = 0
Also plane on conveyer belt will not take of becuse of the same mechanics (only using straight line rather than radial speed)
If your plane is static no air is forced over the wings therefore no lift is produced.
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