Your gibberish doesn't become meaningful or relevant when RP reposts it. You are still not able to point out any error in the diagram.
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Merged DDWFTTW in a “Real” Wind
- Thread starter ynot
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CORed
Penultimate Amazing
My guess is that NALSA's response will be something like, "uh, what?"
ETA: I also think NALSA will be underwhelmed by humber's revleation that winds can gust and change direction.
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I think you're right. But I suspect Bob will also allow us the opportunity to respond to any challenge of our record or data.
Oh, you will be, but that won't help you in the least.
Have you produced that analysis of the data yet?
Stop buggin' him, he's got work to do! Both of you back to your rooms until humber gets his analysis done.
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Yeah, it takes time to make data that contradicts your foregone conclusion appear to support it.
Of course it takes even more time and some really creative thinking when the aforementioned conclusion contravenes reality.
Warning! - Written in “Dummies” speak. . . .
It seems to me that the only frictional advantage of a cart moving at the speed of a wind compared to a cart being pushed up to the same speed in still air is that the cart moving at the speed of a wind doesn’t experience any frictional losses to a headwind. Other than that however both carts experience pretty much (if not exactly) the same energy sapping frictional losses from rolling resistance, mechanical actions and the propeller spinning and thrusting in air.
In the same way that a cart pushed up to a speed in still air can’t sustain that speed merely by a propeller hitting and accelerating air molecules backwards to gain forward momentum from an equal and opposite reaction, a cart moving at the speed of a wind can‘t either as both carts are essentially in still air.
The only way a cart moving at or faster than the speed of a wind can constantly retain that momentum is if the energy losses due to friction are constantly being replaced by energy from the wind. As all parts of the cart are moving at or faster than the wind this energy can’t be transferred DIRECTLY to any part of the cart from the speed of the wind. This includes the propeller regardless that’s it’s spinning at a right angle to the wind. As it’s only the wind that provides energy to the cart it seems to me that there must be some part of the wind that that is essentially moving faster than wind so it‘s able to interact directly with the cart to enable the energy transfer.
I realise this directly contradicts claims that the cart can go faster because it slows part of the wind down.
It seems to me that the only frictional advantage of a cart moving at the speed of a wind compared to a cart being pushed up to the same speed in still air is that the cart moving at the speed of a wind doesn’t experience any frictional losses to a headwind. Other than that however both carts experience pretty much (if not exactly) the same energy sapping frictional losses from rolling resistance, mechanical actions and the propeller spinning and thrusting in air.
In the same way that a cart pushed up to a speed in still air can’t sustain that speed merely by a propeller hitting and accelerating air molecules backwards to gain forward momentum from an equal and opposite reaction, a cart moving at the speed of a wind can‘t either as both carts are essentially in still air.
The only way a cart moving at or faster than the speed of a wind can constantly retain that momentum is if the energy losses due to friction are constantly being replaced by energy from the wind. As all parts of the cart are moving at or faster than the wind this energy can’t be transferred DIRECTLY to any part of the cart from the speed of the wind. This includes the propeller regardless that’s it’s spinning at a right angle to the wind. As it’s only the wind that provides energy to the cart it seems to me that there must be some part of the wind that that is essentially moving faster than wind so it‘s able to interact directly with the cart to enable the energy transfer.
I realise this directly contradicts claims that the cart can go faster because it slows part of the wind down.
What a load of nonsense. Is this some kind of a joke or attempt at sarcasm? An attempt to imitate Humber?
ETA: Sorry, I guess the jokes on me, after reading again I guess its obvious it was posted as a joke,
"it seems to me that there must be some part of the wind that that is essentially moving faster than wind". LOL
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At the risk of taking this full circle, picture your cart sitting in still air. But, instead of sitting on the ground, have it sitting it on a treadmill that's moving backwards. The treadmill turns the wheels of the cart. The wheels of the cart are linked to the propeller. The propeller spins. The spinning of the propeller moves the cart forward.
-- Roger
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It seems like some people are having a problem understanding the "transition" from the cart going below "wind speed" to the cart going faster than "wind speed" - as if there's some reason the propeller will stop working.
But, propeller-driven airplanes are able to fly in still air. That shouldn't seem suprising to anyone. It's the same with the cart. When it reaches the wind's speed, it's the same as if it is in still air.
-- Roger
But, propeller-driven airplanes are able to fly in still air. That shouldn't seem suprising to anyone. It's the same with the cart. When it reaches the wind's speed, it's the same as if it is in still air.
-- Roger
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Cool Stuff at the website
I was just cruising around looking at things. It looks like a whole lot of cool photos were recently posted at the website:
http://www.fasterthanthewind.org
about the building of the BlackBird.
It was great! It answered about a million of my questions!
WindGrins
I was just cruising around looking at things. It looks like a whole lot of cool photos were recently posted at the website:
http://www.fasterthanthewind.org
about the building of the BlackBird.
It was great! It answered about a million of my questions!
WindGrins
I realise what I said sounds ridiculous and perhaps it is. If it’s okay to suggest that part of the wind (air moving relative to the ground) can be slowed down I don’t know what’s so different in suggesting it could perhaps be sped up.
What I’m Trying to do is establish what is happening by eliminating what I believe can’t be happening. What I wrote is a wordy and possibly silly way of saying . . .
I don’t believe it’s possible for a wind to directly transfer energy to anything that is travelling at or faster than the wind.
I don’t believe it’s possible for an equal and opposite reaction to produce enough energy to enable a sustainable series of subsequent equal and opposite reactions. As I understand it an equal and opposite reaction essentially halves energy by dividing it and sending it in opposite directions.
What I’m Trying to do is establish what is happening by eliminating what I believe can’t be happening. What I wrote is a wordy and possibly silly way of saying . . .
I don’t believe it’s possible for a wind to directly transfer energy to anything that is travelling at or faster than the wind.
I don’t believe it’s possible for an equal and opposite reaction to produce enough energy to enable a sustainable series of subsequent equal and opposite reactions. As I understand it an equal and opposite reaction essentially halves energy by dividing it and sending it in opposite directions.
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But an airplane isn’t being powered by the air it’s flying through. It’s being powered by an engine that requires a continuous supply of fuel to give it continuous energy.
I’m not disputing that DDWFTTW works. I know it does as much as I know anything. I’m merely trying to understand exactly how it does work. What you have written doesn’t help in gaining this understanding.
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Neither is the cart. The cart is powered by wind, not air.
It makes no difference to the propeller how it is being powered.
In the case of the aircraft, the engine is making the propeller spin. In the case of the cart, the "engine" is composed of the wheels and whatever belt or gears connect the wheels to the propeller. In both cases, the propeller is spinning and moves the vehicle forward.
-- Roger
Semantics. The airplane isn't being powered by a natural wind.
I think you're wrong about the equality of the losses due to the propeller spinning.
Suppose there's a wind, and the cart is moving at the speed of the wind. To maintain this speed, we don't need to do anything special; that's what the cart would do naturally, pushed by the wind. In particular, the propeller doesn't need to be spun at all, and, left detached from the wheels, it wouldn't spin, because it's in air that's motionless relative to itself. So, in order for the cart to go faster, the propeller doesn't need to be spun very fast. Even a relatively slow spin will give the cart a little extra push, and cause it to exceed wind speed. Therefore, the gears between the driving wheels and the driven propeller can be rather low; that is, the wheels can move quickly but cause the propeller to spin slowly. So the wheels will be easy to turn, in the same way that a bicycle's pedals are easy to turn when the bike is in a low gear.
On the other hand, suppose there's no wind, but the cart is moving at the same speed as before. Now, left detached from the wheels, the propeller would be spun up by the headwind it feels. In order for the propeller to speed the cart up, it needs to be driven faster than the headwind would already spin it. So, the gears between the wheels and propeller need to be higher, making the wheels harder to turn in this case, for the same thrust developed by the propeller.
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