Merged DDWFTTW in a “Real” Wind

[humber]

OK, you're completely caught here. The drfttr cart works. It is very easy to build and demonstrate.

And you can see what? It going "faster"
Well, duh. You need twice the force. Can't see that on a video.

 

[humber]

The "down-the-ruler-faster-than-the-ruler" cart is very simple. No ratchet, no wind, no prop - it's just a gear.

You can demonstrate it for yourself with a wine bottle or glass: place your finger under the neck and push straight forward. When I do that experiment, I see the bottle move "down-finger" faster than my finger. Is that also wrong?

Now that is funny. Measure how far your hand moves.
"Rolls along the finger". Doh.

When I do the (trivial) arithmetic that governs its motion, I find that the speed of the bottle is greater than the speed of the finger. Is that also wrong?

Oh. And the power? That increases too. If you have that, you don't need the gears.

 

[humber]

The topic is a cart in the wind. When faced with the technical, where knowledge is required, you fall back on the trinkets that Spork sold you in the first place.

Gullible.

 

[Llyricist]

And you can see what? It going "faster"
Well, duh. You need twice the force. Can't see that on a video.

Twice the force as what? He continuously uses relative terms without relating to anything.

Hint (if you actually could see this post), the force only governs the acceleration, any amount of force will cause the devices to travel in the same direction.

 

[sol invictus]

Now that is funny. Measure how far your hand moves.

Done. The bottle rolls farther in the same time, just like the cart in the video, and just as simple arithmetic predicts it should.

Is that wrong, humber?

The topic is a cart in the wind.

The topic at the moment is your assertion that the down-ruler-faster-than-the-ruler cart doesn't work. Have you now withdrawn that assertion?

 

[Modified]

And you can see what? It going "faster"
Well, duh. You need twice the force. Can't see that on a video.

Why do you think it is possible to trade speed for force when that force is supplied through a ruler, but not when it is supplied through the wind?

 

[humber]

About Spork's upwind cart.

There are already established trails. The record is 65% WS.
The only peer-reviewed paper, Blackford's, which appeared in the American Journal of Physics in 1975, says >WS is not achievable.

Others have argued that his rotor parameters are too pessimistic, but there have been no advances in rotor design since that time, that can even approach the wish list of the critics.
The winner of the last race, from Stuttgart University, used a variable design optimized in a wind tunnel.

Spork's prop is based on a standard profile, and tinkered with using J-Prop, an internet programme, so it's a bit unlikely to be ground breaking.

There is a limit on the rotor size, and the height, so that competitors can't exploit the wind gradient. Prop size is one of the excuses Spork has already offered, for not entering those competitions. Guess what?

 

[GlennB]

The "down-the-ruler-faster-than-the-ruler" cart is very simple. No ratchet, no wind, no prop - it's just a gear.

You can demonstrate it for yourself with a wine bottle or glass: place your finger under the neck and push straight forward. When I do that experiment, I see the bottle move "down-finger" faster than my finger. Is that also wrong?

When I do the (trivial) arithmetic that governs its motion, I find that the speed of the bottle is greater than the speed of the finger. Is that also wrong?

A spool of fishing line, on edge, line running off the bottom of the spool, pulled towards me, blew several minds at a bbq we had last summer Most people thought the spool would roll away when the line was pulled towards me. That the spool travelled inwards further than the 'pull' caused all jaws to drop.

 

[Modified]

Twice the force as what? He continuously uses relative terms without relating to anything.

Hint (if you actually could see this post), the force only governs the acceleration, any amount of force will cause the devices to travel in the same direction.

Though vague and weasly as usual, I suppose he means that if the cart is designed to move at exactly twice ruler speed, then you would need twice the force to push it at a given speed when pushing on the top wheel than you would if pushing on the body of the cart. He thinks this breaks the analogy with the dwfttw cart for some unknown reason.

 

[humber]

Done. The bottle rolls farther in the same time, just like the cart in the video, and just as simple arithmetic predicts it should.

Is that wrong, humber?

Gee, Prof. Work = force * distance.

When tinkering with your wine glass, did you have a strain gauge at hand to measure the force? The work done to move the glass has 3 components
1) Work of friction against the surface
2) The angular KE required to rotate the glass
3) The KE of its linear motion
You can appreciate that the glass could slide and that would be the linear component. There is also the angular component when it turns.
That is one reason why cars have wheels and chassis attached by axles;
there is no need to provide angular KE for the entire car: just the wheels.

Overall, you have increased the force and the work, so it should "go faster"
Try painting it red.






The topic at the moment is your assertion that the down-ruler-faster-than-the-ruler cart doesn't work. Have you now withdrawn that assertion?[/QUOTE]

 

[D'rok]

Miss D'rok.
You have nothing but the hot air of desperation. Blunt ignorance can do that.

There are two videos here. Not as polished, but just the same as anything Spork has made.

http://img163.imageshack.us/img163/7690/u56.mp4
http://img864.imageshack.us/img864/5312/i0i.mp4

The upwind cart works because, despite its appearance, the prop is better than Spork's. Spork knows little of aerodynamics, so sees L/D ratio as a sign of "goodness".
But it's a ratio. In terms of functionality, would you rather have a 100W prop with and L/D ratio of 4 or a 400W prop with and L/D ratio of 3?

He lampoons Platt's cart, but Platt knows enough to realise that a prop designed to work at speeds >2000 rpm, may not be so useful, so he made one. I used a blade from a 4" desk fan, it works.

There is a video where the BB's prop is turned by hand. From the loss of KE that occurs as it slows, it can be calculated that the static power at 15 rpm is 3W. Laugh.

The "TM" in this video is a belt sander. Yes, the cart moves off the belt, but there are clues that tell you why it does that, which mean, like Spork's TM, it has nothing to do with a cart in the wind.

http://img24.imageshack.us/img24/1811/9ih.mp4
http://img816.imageshack.us/img816/6015/ql0.mp4

My takeaway from this post:

1. You don't know the difference between a prop and a turbine.
2. You don't know the difference between an upwind cart and a downwind cart.

 

[sol invictus]

A spool of fishing line, on edge, line running off the bottom of the spool, pulled towards me, blew several minds at a bbq we had last summer Most people thought the spool would roll away when the line was pulled towards me. That the spool travelled inwards further than the 'pull' caused all jaws to drop.

It is a bit non-intuitive at first, yes - for essentially the same reason the cart is.

Gee, Prof. Work = force * distance.

When tinkering with your wine glass, did you have a strain gauge at hand to measure the force? The work done to move the glass has 3 components
1) Work of friction against the surface
2) The angular KE required to rotate the glass
3) The KE of its linear motion
You can appreciate that the glass could slide and that would be the linear component. There is also the angular component when it turns.
That is one reason why cars have wheels and chassis attached by axles;
there is no need to provide angular KE for the entire car: just the wheels.

Overall, you have increased the force and the work, so it should "go faster"
Try painting it red.

Am I to take this incoherent post as an admission that you were wrong, and that you now agree that the down-ruler-faster-than-the-ruler cart does indeed work?

 

[humber]

Though vague and weasly as usual, I suppose he means that if the cart is designed to move at exactly twice ruler speed, then you would need twice the force to push it at a given speed when pushing on the top wheel than you would if pushing on the body of the cart. He thinks this breaks the analogy with the dwfttw cart for some unknown reason.

Not quite. There is a point where the reel touches the surface, right?
There is a point above that, where the ruler contacts the reel, correct?
Both move the same distance as the centre of the reel.

Big discovery. If you arrange for something to slide over that point, so moves half the distance, then you can claim the reel move "twice as fast"

Those silly toys have nothing to do with the wind that allowed a sail cart to exceed WS, as it travelled 20 to 30 degrees off wind.

You can already see the genesis of the next trial in progress. It will exploit the wind gradient.

 

[humber]

It is a bit non-intuitive at first, yes - for essentially the same reason the cart is.

ROFL

Am I to take this incoherent post as an admission that you were wrong, and that you now agree that the down-ruler-faster-than-the-ruler cart does indeed work?

http://hyperphysics.phy-astr.gsu.edu/hbase/hoocyl.html#hc1

 

[sol invictus]

ROFL



http://hyperphysics.phy-astr.gsu.edu/hbase/hoocyl.html#hc1

Since you are evidently incapable of expressing yourself coherently, there's no point in further discussion of physics.

Why did you waste your time posting those long screeds about the NALSA trials? Surely you don't think anyone is convinced by them - not when you're incapable of explaining the results of a trivial experiment anyone with a bottle and a flat surface can do in 10 seconds.

 

[humber]

Since you are evidently incapable of expressing yourself coherently, there's no point in further discussion of physics.

Why did you waste your time posting those long screeds about the NALSA trials? Surely you don't think anyone is convinced by them - not when you're incapable of explaining the results of a trivial experiment anyone with a bottle and a flat surface can do in 10 seconds.

Another wonder you may care to consider, is that when pedaling a bike, there are times when the foot moves faster than the bike, and sometimes slower!

Somehow, that doesn't seem to affect the amount of work.

 

[Llyricist]

Another wonder you may care to consider, is that when pedaling a bike, there are times when the foot moves faster than the bike, and sometimes slower!

Somehow, that doesn't seem to affect the amount of work.

The rest of us understand leverage, do you?

 

[sol invictus]

Another wonder you may care to consider, is that when pedaling a bike, there are times when the foot moves faster than the bike, and sometimes slower!

Somehow, that doesn't seem to affect the amount of work.

You can demonstrate it for yourself with a wine bottle or glass: place your finger under the neck and push straight forward. When I do that experiment, I see the bottle move "down-finger" faster than my finger.

Since you are evidently incapable of expressing yourself coherently, there's no point in further discussion of physics.

I've given you the finger, and you failed to comprehend it. Will repetition help?

 

[Myriad]

While I understand this is not in the area of the paranormal, I'd love to get Randi's opinion on this thing. Any chance he'd weigh in?

I'd guess (and it's really only a guess) that that is unlikely. And it's not really in Randi's range of expertise; he's more likely to respond to commentary on it by an expert he trusts on the subject, especially if that commentary related to some point about critical thinking. Especially if there were something to make it a "skepticism and society" issue, in the absence of any obvious social significant like millions of people spending millions or billions of dollars annually on bogus DDWFTTW-prevention measures, or lobbying for anti-DDWFTTW legislation.

What's next for us is going upwind faster than the wind. I picked up the second carbon mast yesterday, so we should be ready to start building the turbine blades. All we need now is humber's prediction that it can't possibly work. He can later tell us how we're going about it all wrong.

That's cool. The odd thing is, to me the "faster than the wind" criterion is not as striking in the upwind case. The key mental hurdle (I think, for most people) is imagining a wind-powered vehicle sustaining any "against the apparent wind" state. For directly downwind, that's faster than the wind, but for upwind, it's going upwind at all. Transitioning from upwind-a-bit-slower-than-the-wind-speed to ditto-a-bit-faster-ditto doesn't have the same sense of breaking through a barrier, whether mental or physical.

At the same time, there never seemed to be nearly as much resistance to the possibility of "directly upwind at all," perhaps because the mental models are simpler to grasp (e.g. taking a windmill, putting it on caterpillar tracks, and gearing the rotor to the track drive so that it crawls a millimeter "forward" into the wind for every 10 rotations of the rotor).

Between the Blackbird and the "Forebird," might they lead to an all-direction vehicle? Or has that already been done?

Respectfully,
Myriad

 

[Jack by the hedge]

1) The power is said to come from the wind Yes, it does
2) The ratchet will prevent force from the wind being applied to the wheel The force of the wind is acting to try to slow the prop down. The tension in the drive chain is always such that it is the wheels driving the prop, not the other way round. It's astounding that you keep pointing out an irrelevant non-issue after all this time.
3) Your proposal would result in a reduction of force. I'd ask you to explain exactly what you mean by that, but since it's clearly based on a fundamental misunderstanding, there may not be much point.

The usual bleating about me not understanding that the wheel driving the prop fails, because the claim is that the power comes from the wind.
The original claim, and there have been many, was that the ground drives the wheel.

When that became too cranky, the wind became responsible, but the idea fails if the claim that the wheel drives the prop is maintained. Yet all of those claims are true: The power comes from the wind. The wind pushes the prop forwards. The prop pushes the cart forwards. Friction between the ground and the wheels forces the wheels to turn. The wheels turn the propeller to keep its blades advancing sufficiently quickly through the air that the wind is always acting on the back of the blades despite the fact that the cart is advancing faster than the wind itself.

A turbine which drives the wheels forwards can take energy from the wind, and the force in the shaft will increase and drive the cart forwards. That's not what's happening here, though.

But, a wheel that is said to drive the prop, but takes energy from the wind ( or the difference between the ground), in order to drive the cart means that force will fall, as the wind is applied.
That is basic mechanics. If the force were to rise, then it would increase without bounds. Spin it, and it would drive itself harder and so forth. A PM machine. That is still incorrect and it should be clear by now that it will not become correct by repetition. You are confusing two different components of the force acting on the propeller: the turning force which resists the turning of the prop and the force acting normal to it which pushes the prop directly forwards. The former force causes some loss of power, but the latter force powers the cart.

Spork's proposal has always been PM, and so many have said. He denies this, saying it looks like it is, and devises many ruses to hide that fact, but
he has been caught out by the ratchet he left behind. Au contraire. The ratchet merely proves that the wheels drive the prop and not vice versa. But if you had grasped the principle by which the cart works, you would expect the wheels to drive the prop.

My comments in red.