Downwind faster than the wind. Poll

[snowleopard]

Moving the ruler to the right against the roller will not drive the cart to the right.....So it will accelerate to the left.

Now watch it in action (skip to 1:40 to avoid silly preamble).

 

[lw395]

The road is the source of energy, and you use it to do work on the wind.

NO!
the road does not accelerate, change state or temperature, except perhaps a little frictional warming...
It does not give up any energy to anything else.

 

[nmeyrick]

It's getting confusing switching between threads. I'm beginning to regret starting the second one.

I think I can answer that question. Look at this mechanism....

The cart moves around 3 times as fast as the ruler above it. Now replace the upper wheel rolling along the ruler with a prop moving through the air - just another linkage but this time with an inefficient coupling.

We won't get 3x speed of course because of prop slip but with a good prop we will get more than 1x.

Sorry, you're changing the subject because you can't refute my assertion that the mechanism you described is breaking the conservation of energy.

The ruler thing is a complete red herring, it simply illustrates the principle of gearing. If I have a bike with a 3x gearing and I turn the pedals through a full rotation, the rear wheel will turn through through three full rotations. That doesn't mean I can accelerate any more than the force I put in by turning the wheels (F=MA) and I certainly can't suck extra energy out of the road.

 

[nmeyrick]

The road is the source of energy, and you use it to do work on the wind.

Like I said, conseration of energy. The road has no energy in and of itself, only in relation to the cart. Honestly, if you step off the cart the road stops moving.

So using the road to power the cart is exactly the same as using the cart to power itself.

 

[lw395]

I can't access u-tube here, sorry.

 

[snowleopard]

The ruler thing is a complete red herring

No. It most certainly isn't a red herring. It illustrates that a vehicle operating between two media can move faster than either medium. In the mechanical example shown the media are two solid surfaces, in the prop driven machine the media are a solid surface and a moving mass of air. Exactly analogous.

The conservation of energy is the red herring. Most people referring to it, or the laws of thermodynamics or perpetual motion are confusing energy with speed. The energy input comes from the kinetic energy of the air relative to the ground, the energy consumed is in overcoming friction & drag. There is nothing in 'conservation of energy' to say that a large force moving through a short distance can't be transformed into a small force moving through a greater distance. You've only to let go of your mainsheet to see that happening.

 

[DeeGee]

I can see one fly in the ointment.

The air around the belt is indeed instantaneously moving at x mph in the opposite direction to a point on the belt. A man standing still on the belt would feel a headwind due to his motion through the air If, however he was running fast enough to retain his position relative to the room, he would experience no air movement at all, no wind.

Since it is the movement of the belt relative to the room's airmass which is creating this relative wind, the device sees no wind since the device is not moving in relation to the rooms airmass . This means that whatever is causing the aircraft to NOT just follow along the belt, it is not air movement. Repeat: there is no air movement relative to the aircraft.

My guess is that it is the old conjurours trick, a very fine filament holding it in position.

(...of course, I just could be wrong.... hehe)

 

[snowleopard]

I can't access u-tube here, sorry.

Well I'll tell you what happens - the ruler moves to the right and the cart moves to the right about 3 times as fast. Quite surprising but that's what happens and once you've seen it you can easily work out the forces involved. Do watch it when you can because until you take this on board you won't see how the DDWFTW experiment works.

 

[bbg]

Super Geek and the Snow Cat are trolling, and doing a very good job of it. They are moving the goalposts as they please, mixing theories.

Please don't feed the trolls.

 

[nmeyrick]

Super Geek and the Snow Cat are trolling, and doing a very good job of it. They are moving the goalposts as they please, mixing theories.

Please don't feed the trolls.

Sadly I'm forced to agree; I have an innately optimistic view of human nature and thought I saw people with a genuine misunderstanding I could help correct.

I have better things to do than encourage them any further.

 

[snowleopard]

They are moving the goalposts as they please, mixing theories.

No goalposts moving here. All along I have been saying the source of the power is the machine acting between two media moving at different speeds. All the antis are also saying the same thing in many ways: they can see only the lack of air movement relative to the machine and are unable to see the critical importance of the relative motion of road and air.

For those who have closed their minds to the possibility they may be wrong there can be no understanding. I started out a cynic but I sat down, analysed what was going on and understood it.

Just don't get into any heavier-than-air machines, stick to balloons if you want to fly.

 

[halfway]

"Or are you saying that there's no speed limit to a propellor driven aircraft? "

I think this will make it clear.

Every prop aircraft has a speed limit. It has nothing to do with its strength. It has nothing to do with friction. Nothing to do with air friction. Nothing to do with any energy loss system.

,It is simply that at its maximum pitch angle, and maximum throttle, if you take it into a dive at high speed. the apparent wind on the prop stalls on the blade and the prop is useless. The forward velocity makes a wind component . The rotational prop speed makes a wind component. Add them together and they hit the prop blade at an angle.

On the ground the rotational speed makes the apparent wind angle close to the plane of the prop. As the air speed increases the apparent angle bends forward of the craft. When it gets bigger than the minimum angle of the attack the prop it is useless. That determines the speed limit.

OK you can exceed this using gravity to help, but that leaves you standing on your prop as it is now a drag, not a means of propulsion. Your engine will go overspeed and death following shortly afterwards.


Back to boaty things. The same, but reversed, issue is seen on boats that stand at the dock with the engines at full bore. The engines produce large amount of black smoke and the props cavitate and destroy themselves. People paid us to fix these things. There is nothing wrong, they were just was never designed to see water hitting their blades at that angle. Once out of port and travelling along the apparent water flow is at the correct angle and the engines are loaded much less.

 

[RAI]

Propellers designed to have a large speed range have adjustable pitch. I understood the limit with such propellers comes when the tip speeds start to go supersonic. At that speed, apart from the noise issue, there is a flutter issue too.

However, in the DDWFTTW experiment, not such speeds will be reached. I see the latest man carrying machine seems to have adjustable pitch. Just like BMW Oracle, it will be able to trim.

 

[nmeyrick]

For those who have closed their minds to the possibility they may be wrong there can be no understanding. I started out a cynic but I sat down, analysed what was going on and understood it.

Just don't get into any heavier-than-air machines, stick to balloons if you want to fly.

Thanks Snowleopard; I think that by dissembling, changing the topic and finally resorting to cheap jibes (or should that be gybes?) about heavier than air travel you have expressed, far more eloquently than I could, that you are out of sensible arguments.

I hope you bear me no ill will, as I bear you none. It's been stimulating, fun even, but I think my work here is done so you will have to find some other sparring partner to wind up -sadly I have no doubt that you will. You have been nothing but pleasant and civil to me, and I would like to imagine our discussion taking place, not on an impersonal internet forum, but in a smoke filled and wood pannelled gentleman's club, and ended by a hearty handshake. But you have wronged a far greater party than myself. You have wronged science, and that saddens me and is something I cannot allow to pass unchallenged. Call me a sentimental fool but public understanding of science is at an all time low in our society, and anything which harms it further in the minds of the easily impressionable must be resisted.

Firstly please do me a favour and desist from claiming that one grainy video on youtube "proves" this, or another grainy video "refutes" that. I have seen the inside of the Tardis on youtube, but that don't make it so. Proof is a very big thing, and it doesn't look like the videos you post. It looks like hundreds or thousands of repeated experiments, with very accurate measurements demonstrating a statistically significant effect. Which is then repeated by completely independent experimenters, not once but many times. And finally is subjected to independent peer review and published in a reputed journal. There is a good reason why people study for years to earn a Phd, and why you cannot download Nobel prizes online.

Secondly please stop insulting those who have the temerity to disagree with you by comparing them dismissively to those who doubted the Wright brothers. There is a very fuzzy logic in saying that "People doubted the Wright brothers. The Wright brothers were right. People doubt me. Therefore I am right." But more importantly there is a well established principle in science that the burden of proof lies with the innovator. For every Wright brother there are countless purveyors of flogiston or cold fusion, and part of the role of science is to challenge these and expose them up as misguided at best or charlatans at worst. You need to grasp that whilst the Wright brothers were right, people were completely rational to doubt them. The burden of proof was with the brothers to demonstrate their idea, and not on anyone else to show them wrong; and because they were correct the rose to the challenge and gave birth to a multi billion pound global industry.

When this mechanism has passed those tests - which it surely must do if it is correct, as its economic value would be enormous - then I will change my mind. I am no more closed minded than you, I merely demand a higher standard of evidence.

When this is proven I will be the first to climb into an ultra high speed train, powered by the differential in speed between its one driven rail and its one fixed rail - simply your ruler on its side of course - and buy you a pint to apologise. But until then I have better things to do.

Peace out.

 

[Pierrome]

Firstly please do me a favour and desist from claiming that one grainy video on youtube "proves" this, or another grainy video "refutes" that. I have seen the inside of the Tardis on youtube, but that don't make it so. Proof is a very big thing, and it doesn't look like the videos you post. It looks like hundreds or thousands of repeated experiments, with very accurate measurements demonstrating a statistically significant effect. Which is then repeated by completely independent experimenters, not once but many times. And finally is subjected to independent peer review and published in a reputed journal. There is a good reason why people study for years to earn a Phd, and why you cannot download Nobel prizes online.

This is a completely ridiculous statement.
The "downwind cart" is a simple device, easy to make, of which an instructional video of how to make it is available on Youtube. Anyone who has even the slightest constructional ability and intelligence can easy make one and prove to themselves or anyone else that it works and there is no trickery involved.
Why would a study of such a simple device need to be subject to an "independent peer review" when any fool can make one and see for themselves?
Don't complain about "grainy" videos and insist on "statistically significant effects" when anybody can put one together and SEE that it actually works.

It's not rocket science, we are not talking about high-flown theory here. The question is easily resolved by simple experiment by anybody!

 

[snowleopard]

you are out of sensible arguments.

I 'ran out of arguments' a long time ago. There is a limit to the number of ways you can explain how it works.

I have proved in the simplest terms that that direct motion downwind by one mechanism is possible (towing behind Oracle or a land yacht) yet still people come back with nonsense like 'perpetual motion'. I have shown the 'under the ruler' demonstration and explained its connection but rather than think it through it is dismissed as 'irrelevant'. Video evidence is dismissed because it's low-res. (Presumably you don't believe the news unless you see it in HD).

I have been called a troll, stupid, even -by you- a liar - yet when I liken the arguments to the ones that went on before heavier-than-air flight I am being 'cheap'.

It's pointless trying to debate with someone who sticks their fingers in their ears and shouts LA LA LA. That's what this has become. I won't bother any more.

 

[RAI]

For those who would like a little more mathematics and a lot less polemic, have a look at Mark Drela's analysis and the discussion here (in message 3 on the thread).

http://www.boatdesign.net/forums/propulsion/ddwfttw-directly-downwind-faster-than-wind-25527.html

 

[DJE]

It's pointless trying to debate with someone who sticks their fingers in their ears and shouts LA LA LA. That's what this has become. I won't bother any more.

Well done. You stuck it out a lot longer than I did.

 

[cliffordpope]

That works and here is the film of it in action. (skip the 1st 1min 40 secs). That shows a mechanism that uses the relative movement of two surfaces to produce motion faster than the original.

Now replace the ruler and wheel with air and prop. The coupling is a lot less efficient but it does the same job.

That's very clever and I am (nearly) convinced.

So if we imagine fitting some blades onto the large wheel, and then replacing the ruler by a stream of wind, or perhaps a stream of sawdust blown by the wind, the device will still work?

 

[Ubergeekian]

NO!
the road does not accelerate, change state or temperature, except perhaps a little frictional warming...
It does not give up any energy to anything else.

If you use a reference frame moving with the trolley it does! How? By exerting a force on the rim of the wheels while moving.