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Google-Backed Wind-Powered Car Goes Faster Than the Wind

timothy posted more than 4 years ago | from the duh-it's-pushed-by-the-google dept.

Google 393

sterlingda writes "A wind-powered car has been clocked in the US traveling downwind 2.85 times faster than the 13.5 mph wind. The definitive research by Rick Cavallaro of FasterThanTheWind.org is being funded by Google and Joby Energy. The run should now settle the DWFTTW (downwind faster than the wind) debate that has been raging for some time on the Internet about whether or not such a feat was possible."

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What debate ? (-1, Troll)

daveime (1253762) | more than 4 years ago | (#32474242)

Send any wheeled vehicle down a 1 in 4 decline and for sure, it'll go faster than the opposite blowing wind ...

Re:What debate ? (5, Informative)

Jedi Alec (258881) | more than 4 years ago | (#32474266)

If you'd read some of the provided links, you'd have seen that the requirement was for the vehicle to be powered solely by wind, so no gravity involved except in its usual role of keeping the wheels on the ground ;-)

In other news, scientists actually getting their hands dirty turn out to know more about their chosen field than a bunch of people on the interwebz.

Re:What debate ? (2, Funny)

Bazman (4849) | more than 4 years ago | (#32474374)

True. I bought some water skis and spent ages looking for a lake with a slope.

Re:What debate ? (2, Informative)

History's Coming To (1059484) | more than 4 years ago | (#32474484)

The things you're looking for are called "waves" ;) http://www.youtube.com/watch?v=y7mmO0CsyZA [youtube.com]

In related news, kitebuggies will generally travel at three times the wind speed, depending on the aspect ration of the kite.

Re:What debate ? (3, Funny)

Notegg Nornoggin (1175269) | more than 4 years ago | (#32474600)

> I bought some water skis and spent ages looking for a lake with a slope.

The term is "Asian", you politically incorrect clod!

Re:What debate ? (1)

DaveGod (703167) | more than 4 years ago | (#32474642)

I'm no engineer but my reading of TFA suggests -1 Troll is a little harsh.

Cavallaro explained the car is able to move faster than the wind because the propeller is not turned by the wind. The wind pushes the vehicle forward, and once moving the wheels turn the propeller. The propeller spins in the opposite direction to that expected, pushing the wind backwards, which in turn pushes the car forwards, turning the wheels, and thus turning the propeller faster still.

OK I'm speculating in my ignorance here, but isn't this basically saying the wind pushes the car forward initially slower than the wind, but building up momentum that it later utilises to power the propeller (activating stored energy)? The initial bit is fundamentally the same as pushing a (non-propeller) vehicle up a slope to store the energy. Or simply compressing a spring or whatever.

Re:What debate ? (1)

Goaway (82658) | more than 4 years ago | (#32474868)

No, that is not what it is saying. Given an open plain and constant wind, it will move faster than the wind indefinitely.

Re:What debate ? (1)

snowboardin159 (1744212) | more than 4 years ago | (#32474960)

negative, as soon as the vehicle moves forward at all, a direct link to the propeller moves the prop in a direction against the wind (backwards for the vehicle) instantly providing some extra force against the wind. This is actually pretty ingenious. I like where this is going.

Possible upwind? (0)

Anonymous Coward | more than 4 years ago | (#32474250)

I misread this initially, and thought the car travelled into the wind.

It's still pretty weird thinking through it.

Re:Possible upwind? (1)

dtmos (447842) | more than 4 years ago | (#32474556)

It's possible to design a car that will travel into the wind, although the net power flows in the reverse from the present example -- going upwind, the power would flow from the propeller (which would probably look more like a turbine than a propeller) to the wheels.

Debate? (4, Interesting)

Mikkeles (698461) | more than 4 years ago | (#32474252)

Sailing vessels can go faster than the wind, why shouldn't a car be able to?

Re:Debate? (0)

Anonymous Coward | more than 4 years ago | (#32474262)

How is this possible?
Earnest question.

Re:Debate? (1, Informative)

Anonymous Coward | more than 4 years ago | (#32474292)

Ignore the sail and the turbine.
You have a car pushed by the wind. Just like blowing a toy car from behind. This is a light car, and imagine a strong wind.

As the car moves, the wheels turn. There is enough wind force pushing the car to overcome the friction and momentum of the wheels->propeller. So at the moment, the car is being pushed by the win. In addition, the propeller pushes the car forward further. At least that's what I think they're saying.

I still reckon that to get any useful thrust from the propeller, you would need to take so much energy from the wheels, that the whole thing would grind to a standstill.

There's something perpetual motion about this get-up.

Re:Debate? (0)

Anonymous Coward | more than 4 years ago | (#32474308)

So at the moment, the car is being pushed by the win. In addition, the propeller pushes the car forward further.

I still reckon that to get any useful thrust from the propeller, you would need to take so much energy from the wheels, that the whole thing would grind to a standstill.

There's something perpetual motion about this get-up.

Wrong way round - the wind accelerates the propeller, and that drives the wheels. The propeller is effectively a sail

Re:Debate? (3, Informative)

ls671 (1122017) | more than 4 years ago | (#32474388)

Read TFA, parent is correct concerning the wheels :

Cavallaro explained the car is able to move faster than the wind because the propeller is not turned by the wind. The wind pushes the vehicle forward, and once moving the wheels turn the propeller. The propeller spins in the opposite direction to that expected, pushing the wind backwards, which in turn pushes the car forwards, turning the wheels, and thus turning the propeller faster still.

Re:Debate? (4, Interesting)

dtmos (447842) | more than 4 years ago | (#32474402)

Ah, no. I can do no better than to quote ThinAirDesigns [physorg.com] :

The key thing to remember is that due to the tailwind, the wheels are traveling over the ground much further than the propeller is traveling through the air[1] -- thus using the force x distance calculations for work and power it's easy to see that when we are traveling the speed of the wind, we can gain more power from the wheels (faster moving ground) than we have to expend in the air (slower moving air).

________
[1] As he is about to mention, this is best considered at the moment when the car is moving at the speed of the wind. In this case, there is no wind over the propeller, since the car and the wind are traveling at the same rate in the same direction; however, the wheels are moving relative to the ground at the speed of the wind, and therefore turn the propeller and supply additional thrust to the car, accelerating it.

Re:Debate? (0)

Anonymous Coward | more than 4 years ago | (#32474518)

He appears pretty confused about this TBH. He states elsewhere on that page that it works by having rotating sails which are inclined to the wind.

The "wheels drive the propeller" thing is clearly bs. Where would the energy come from??

Re:Debate? (2, Interesting)

dtmos (447842) | more than 4 years ago | (#32474608)

The rotating sails (i.e., propeller blades) are inclined to the wind; it's how all propellers work -- when rotated, they provide the force to the car that accelerates it to speeds higher than the wind. However, the power flow is from the wheels to rotate the propeller, not the other way around.

He states quite clearly, several times, that they don't use the "sail" word, because it confuses people into thinking that the power flow is in the opposite direction. Like all propeller-driven craft, the power flow is from the craft to the propeller.

The energy comes, ultimately, from the wind. One might as well ask, "Where would the energy to move a sailboat faster than the prevailing wind come from?"

Re:Debate? (2, Insightful)

Anonymous Coward | more than 4 years ago | (#32474758)

however, the wheels are moving relative to the ground at the speed of the wind, and therefore turn the propeller and supply additional thrust to the car, accelerating it.

Am I stupid, or is there another reality where the laws of thermodynamics don't apply?

What you described can't increase the vehicle's momentum, because it's adding resistance to the car wheels (there's no actual gain in energy being described in your statement, just gibberish about potentials).

The only way to go faster than the wind is to resist gaining speed (store energy), and when wind speed is eventually reached, expend the stored energy to go a bit faster than the wind. After that stored energy is used up, the vehicle slows back down to wind speed. Not magic.

Re:Debate? (2, Informative)

wrook (134116) | more than 4 years ago | (#32474294)

IANAP (physicist) - The wind hits the sail. Since it's hitting the sail on one side and not the other, the pressure is higher on the side where the wind is hitting. This means that the sail is sucked towards the low pressure side. The speed of the craft is dependent upon the pressure difference that you are able to make and the amount of inertia and friction of the vehicle. It's not really related to the speed of the wind (other than higher speeds can create higher pressure differentials).

Re:Debate? (4, Funny)

wrook (134116) | more than 4 years ago | (#32474320)

I started to think about this more. And the more I thought about it, the more confused I became.

Finally, I came to the conclusion: Thank god I'm not a physicist!

Re:Debate? (0)

Anonymous Coward | more than 4 years ago | (#32474364)

go (stay?) online and do a search for some old films by Asher Shapiro. Watch them. They are absolutely brilliant, and will deconfuse your brain while they entertain. I'm somewhat convinced that these films are in large part responsible for getting the US to the moon.

Re:Debate? (5, Informative)

Pharmboy (216950) | more than 4 years ago | (#32474412)

I hate spelling nazis, but since you are suggesting a search, the correct spelling is Ascher H. Shapiro [wikipedia.org] . I only found this out as I was trying to take your advice and search for him.

I hate illiterate dumb arses (0, Troll)

Anonymous Coward | more than 4 years ago | (#32474574)

I hate illiterate dummies who revel in their own, or more often, other's ignorance, preferring for everyone to be ignorant rather than have to make the effort to communicate more efficiently.

Mind you, the other poster put it better. Crab in a bucket.

Re:Debate? (0)

Anonymous Coward | more than 4 years ago | (#32474298)

I think it should be obvious. A sail is capturing energy. The larger the sail or more efficient the design, the more energy it captures. At a certain point it can be capturing more energy than is required to move the object at the speed of the wind. At that point the extra energy can be used to go even faster.

Re:Debate? (1)

MichaelSmith (789609) | more than 4 years ago | (#32474366)

Same way an aircraft can move forward faster than it is descending while gliding. But I don't see how a sail boat can move faster than the wind when moving with the wind, unless you invoke storage.

Re:Debate? (2, Insightful)

anegg (1390659) | more than 4 years ago | (#32474764)

Because the comparing the velocity of the wind and the velocity of the car is a bogus comparison. In order to not be a perpetual motion machine, it is only necessary for the energy of the wind (available to the car) to be more than the energy required for the car to accelerate to and maintain a particular velocity. The tricky part is in extracting the energy from the wind when the velocity of the car exceeds the velocity of the wind. But that is an engineering problem, not a metaphysical problem.

Re:Debate? (1)

Psychofreak (17440) | more than 4 years ago | (#32474790)

Iceboats hare typically clocked in the 50mph+ range, with wind as low as 5 mph, though more typically 10 mph wind. The wing shape of the sail and the angle of apparent wind make the vessel move faster downwind by tacking than going in a straight line.

http://en.wikipedia.org/wiki/Sailing_faster_than_the_wind [wikipedia.org]
http://torontoist.com/2010/01/historicist_sailing_faster_than_the_wind.php [torontoist.com]
http://www.straightdope.com/columns/read/2908/how-can-racing-yachts-sail-faster-than-the-wind [straightdope.com]

video of the mentioned BUFC
http://skepticblog.org/2010/05/27/sailing-directly-downwind%E2%80%A6-faster-than-the-wind/ [skepticblog.org]

This is a unique solution, but I think is more of a gee wiz than a practical device that will have economic value.

Phil

Re:Debate? (5, Insightful)

Anonymous Coward | more than 4 years ago | (#32474338)

Sailing vessels only go faster than the wind when they travel with the wind coming from the side. No matter how fast the vessel goes, the wind keeps blowing from the side and delivering energy to the vehicle. When you try to go faster than the wind in the direction of the wind, the relative motion to the air goes down to zero and then you start going against a head wind. Obviously the wind can not be the propelling force beyond the point where you go as fast as the wind in the conventional sailing sense, because at that speed there is no wind (motion is relative). The described device uses the sailing force to accelerate and then produces its own faster wind, so to speak, by driving a propeller via a transmission from the wheels.

Re:Debate? (3, Insightful)

supercrisp (936036) | more than 4 years ago | (#32474400)

And the propellor is a "sail" whose surfaces are not perpendicular to the wind.

Re:Debate? (0)

Anonymous Coward | more than 4 years ago | (#32474476)

The propeller does not act as a sail. It does not receive energy from the moving air.

Re:Debate? (0)

Anonymous Coward | more than 4 years ago | (#32474872)

Then what does?

Re:Debate? (1)

Yvanhoe (564877) | more than 4 years ago | (#32474772)

From what I understand, this car was going against the wind

Re:Debate? (1)

BasilBrush (643681) | more than 4 years ago | (#32474838)

You understand 180 degrees wrongly.

Re:Debate? (2, Insightful)

Anonymous Coward | more than 4 years ago | (#32474368)

Sailing vessels can go faster than the wind ACROSS the wind. They use a keel to do this. But the keel does nothing (except drag) when they travel directly downwind. They can't go faster than the wind in the direction of the wind. If you think it through what these guys are doing is pretty clever, making the car travel faster than the wind providing it's power in the direction the wind is blowing is cool.

Re:Debate? (1)

houghi (78078) | more than 4 years ago | (#32474392)

They do not go faster downwind.

Re:Debate? (1)

TheLink (130905) | more than 4 years ago | (#32474646)

But now I wonder if wind powered boats can use the same trick to go downwind faster - instead of wheels you'd use propellors or paddles in the water.

Re:Debate? (0)

Anonymous Coward | more than 4 years ago | (#32474856)

Hull drag would kill a lot of the potential advantage in that though. Wheeled vehicles can have pretty low rolling resistance to begin with, and thus have much better efficiencies starting out. Now if you made your boat a hydrofoil or figured out some other trick to reduce the hull drag, then it might be worth looking into.

Now lets see somebody try this on the tabletop with some LEGO Tecnics models.

Re:Debate? (2, Interesting)

Rigrig (922033) | more than 4 years ago | (#32474396)

But sailing vessels can't go faster than the wind directly downwind, this car does.

FTFA:

the propeller is not turned by the wind. The wind pushes the vehicle forward, and once moving the wheels turn the propeller. The propeller spins in the opposite direction to that expected, pushing the wind backwards, which in turn pushes the car forwards, turning the wheels, and thus turning the propeller faster still.

Re:Debate? (4, Interesting)

SerpentMage (13390) | more than 4 years ago | (#32474450)

Look at the experiment I would say sure its possible because there is no resistance. As they say they can't do this on a gym floor, but a tread mill.

As a mechanical engineer who studied dynamics I would say the reason is because the resistance that is normally hit due to acceleration or keeping the thing moving is not present. Thus this thing could accelerate faster than the wind.

What I would find interesting is what are they exploiting in specific? As they say, is there some neato resistance, aero-dynamic trick that nobody has yet thought of?

It reminds me of the ram jet that below a certain speed is useless. YET at higher speeds it becomes more effective than a regular jet.

Re:Debate? (1)

naasking (94116) | more than 4 years ago | (#32474766)

Sure they can [wikipedia.org] . The key is to couple the wind power to an mechanism providing thrust, like the wheels in this scenario, or a propeller for a boat.

Re:Debate? (1)

BasilBrush (643681) | more than 4 years ago | (#32474870)

The wheels don't provide thrust in this example. The wheels turn the propellor, not the other way around.

Re:Debate? (0)

Anonymous Coward | more than 4 years ago | (#32474908)

That's misleading. The wheels in this scenario do not provide thrust, the propeller does. The energy is extracted from the speed difference between the wind and the ground and transferred to the propeller.

Re:Debate? (1)

ConfusedVorlon (657247) | more than 4 years ago | (#32474486)

they can't go downwind faster than the wind.

Re:Debate? (0)

Anonymous Coward | more than 4 years ago | (#32474702)

Actually yes, they can. I've seen a video of the thing. They put a streamer at the top to indicate the relative wind. When stationary, the wind was blowind directly to the front of the vehicle, once it got up to speed it sort went limp, then when it surpassed the speed of the wind, it pointed away from the front of the vehicle.

Re:Debate? (1)

Jawnn (445279) | more than 4 years ago | (#32474740)

Not downwind, they can't. RTFA.

Re:Debate? (1)

deander2 (26173) | more than 4 years ago | (#32474904)

sailing vessels cannot go faster than the wind when sailing directly downwind.

Re:Debate? (1)

kenj0418 (230916) | more than 4 years ago | (#32474914)

Sailing vessels can go faster than the wind, why shouldn't a car be able to?

I agree. Let me know when they have a light powered vessel that goes faster than light, then I'll be impressed.

Jews for Nerds! (-1, Troll)

Anonymous Coward | more than 4 years ago | (#32474258)

Jews, also known as kikes, hebes, hymies, yids, gold niggers, oven magnets, hook noses, sheenies, swindlers, criminals, "firewood", and Arabs in denial are a subhuman species of reptilian extra-terrestrials and adherents to one of the world's oldest major religions, called "Judaism", otherwise known as "The Worship of Money" or "Eating Arab Babies".

Judaism was the world's first master race theory. The Jew religion teaches that Jews are the Chosen People of God and that there is a sacred mystical quality to Jew DNA. In olden times, Jew prophets would, under the command of YHWH, frequently lead the Jews on genocidal rampages against neighboring populations, and even today Jew leaders often cite Jewish religious ideals to justify their ongoing genocide of sandniggers. Judaism ironically found its mirror-image inversion in the anti-Jew Aryan racialism of the Nazis.

Despite only being 0.22% of the world's population, Jews control 99% of the world's money. Not only do the Jews control the world, but also the media, the banks, the space program, and LiveJournal's porn communities and Gay communities. All Jews possess the following features: an extremely large nose, fake boobs, curly hair that reeks of faggotry, one of those gay hats, a love of coke, a law practice, a roll of money, a small cock, or shitty taste in dental hygiene.

Jews invented both Communism and Capitalism. Karl Marx, of course, was a Jew, which was why he understood money so well, and in fact he was converted to Communism by another Jew, Moses Hess, the actual founder of Zionism, who ghost-wrote Marx's The German Ideology. Capitalism was created when Christian Europeans threw away their morals and decided to embrace Jewish practices like usury (see: John Calvin). Jews were the first group to create a sophisticated banking system, which they used to fund the Crusades in order to pit Christians and Muslims (both adhering to religions derived from and controlled by Jews) against each other to kill as many people as possible in a macabre human sacrifice to YHWH.

The Jew banking system was based on fraud and lies, so when it inevitably collapsed, the Jews just pwned as many people as possible by unleashing the Black Plague on them. Later, Jews economically controlled medieval Venice (the first modern maritime trade empire), and then crypto-Jewish merchants economically controlled the Spanish Empire, including the slave trade. Openly Jewish bankers orchestrated the Dutch Empire and founded Jew Amsterdam (later Jew York). Later the Dutch Jews moved to London because they thought it would be a better base for a global empire, and actually brought a Dutch nobleman, William III, with them, who they installed in a coup d'état (more like Jew d'état, amirite?) as new King of the British Empire. For hundreds of years, Jewish bankers controlled global trade through their bases in Jew York City and London. European colonialism was, through its history, essentially a plot whereby Jews could gain control of gold and diamond mines in poor countries and increase their stranglehold over the global economy.

Jews also enjoy slicing up baby penises for fun, some even enjoy sucking them. See below.

Jews also created Jew search engine Google, so now they can find all Jew information on Internets.

Some suggest that we should use Jews instead of dogs to sniff out large amounts of concealed cash or anything else worth smuggling at airports due to their sensitive Jew noses. Obviously, this is a horrible idea, because the pay is bad, and the dirty Kikes would probably form a union and demand moar money, thus increasing the burden on taxpayers everywhere.

Very old news. (2, Informative)

StikyPad (445176) | more than 4 years ago | (#32474278)

It shouldn't really be a debate -- sailors have done this for decades. Essentially you turn your vessel/vehicle at an angle to the wind such that you utilize both the positive pressure from the wind and the negative pressure created by the curved sails which create an air foil. Positive pressure pushes you forward while negative pressure pulls you forward == faster than the wind. The same effect is at play with the "propeller" on the car. It's also the same principle that keeps planes in the air -- higher pressure on the bottom of the wing relative to the top.

Re:Very old news. (1)

Ecuador (740021) | more than 4 years ago | (#32474290)

Could you explain it a bit more? When you start going faster than the wind, don't you lose the "positive pressure" of the wind, since it is now against you? What am I missing?

Re:Very old news. (1)

rjk94 (1240212) | more than 4 years ago | (#32474314)

Good point. I am now confused again.

Re:Very old news. (1)

peragrin (659227) | more than 4 years ago | (#32474330)

apparent wind angles and speed.

The faster you go the direction of wind, and it's speed changes. What is hard for most people to under stand there are really no lines on a boat that are solid. even the lines that hold the mast up can be tweaked. while any given boat has a top hull speed, you can design boats with hull speed numbers many times that of the wind. The fastest sailboat to date was clocked doing 60mph, (55knots) in a 30mph(25 knot) breeze. That's doing twice wind speed.

Sailing is areodynamics, hydrodynamics, and a tinker's dream all combined into one package.

Re:Very old news. (1)

rkit (538398) | more than 4 years ago | (#32474386)

You are missing that this is a 2-dimensional problem. Both wind velocity and boat velocity are 2d-vectors. What is required is that the projection of the boat velocity in the direction of the wind is smaller than the wind. The magnitude of the boat velocity can always be greater as that of the wind as long as it does not travel in the same direction as the wind blows.

Re:Very old news. (1)

Hydrogenoid (410979) | more than 4 years ago | (#32474440)

Except that car travels at 2.85 times the speed of the wind, when directly downwind, ie. when the boat and wind velocity vectors are on the same axis.
Of course, since the "sails" (the propeller blades) are moving on a different trajectory, their apparent wind is not directly downwind.

Re:Very old news. (2, Insightful)

AnonymousClown (1788472) | more than 4 years ago | (#32474302)

So all this time, Wile E Coyote could have stood to the side, blown just as hard on his sail and gotten away from his bombs that the Road Runner turned on him?

Some genius!

Re:Very old news. (0)

Anonymous Coward | more than 4 years ago | (#32474370)

yes but most sailors, physicists and internet know-it-alls all believe that when you're going downwind (i.e. the wind directly behind you) it is impossible to go faster than the wind. This is why sailors do not like going downwind, they'd prefer (mostly, depending on the boat) to be on a beam reach (i.e. wind coming directly at a right angle to the boat, so you sail forward and wind comes directly from the side).

This work has proven that it is in fact possible to go downwind, with the wind behind you, faster than the wind could push you alone. I personally can't quite understand how this is possible, it certainly isn't possible with sails (in fact, the arguments against it are /from/ the sailing community, if you rtfa) but the evidence is compelling and i'm considering building one myself to do some testing.

Re:Very old news. (1)

MichaelSmith (789609) | more than 4 years ago | (#32474448)

This work has proven that it is in fact possible to go downwind, with the wind behind you, faster than the wind could push you alone. I personally can't quite understand how this is possible

It seems to be like you have this big propeller which is pushing the air backwards at 10 m/s. The wind pushes your vehicle forwards at 5 m/s but it also pushes the air from the propeller forwards at 5 m/s. Because this air is already being pushed back at 10 m/s the wind pushes it forwards at 15 m/s. In doing so it pushes the propeller and the car forwards at 15 m/s.

Re:Very old news. (0)

Anonymous Coward | more than 4 years ago | (#32474626)

A to me clearer description is: They do not use the wind speed itself direct, but they make use of the delta between wind speed and ground speed.
Or a even different way to put it:
If there is no wind, and you want to go at e.g. 5 km/h using a propellor needs N energy.
Now assuming you have a wind speed of 20 km/h. If you are already somehow running at 20 km/h if you had no friction on the surface you'd still need the same energy N to go 5 km/h _faster_ using a propellor (since on the air side you can't distinguish the two situations). However since you are already travelling at 20km/h relative to the ground, extracting that energy N from the wheels does not slow you down by 5 km/h, thus you have an overall speedup.

Re:Very old news. (1)

Jedi Alec (258881) | more than 4 years ago | (#32474382)

It shouldn't really be a debate -- sailors have done this for decades. Essentially you turn your vessel/vehicle at an angle to the wind such that you utilize both the positive pressure from the wind and the negative pressure created by the curved sails which create an air foil.

Ahhh, but the debate is about going faster than the wind while going downwind. So no angles involved.

Re:Very old news. (4, Informative)

waimate (147056) | more than 4 years ago | (#32474432)

You are correct, but only for boats sailing across the wind or to windward. Modern yachts cannot sail faster than the wind *downwind*. Indeed, downwind is their slowest point of sailing, which is why many yachts tack downwind rather than sail dead downwind. Sailing boats cannot do what is claimed here. What is claimed here is substantially cool.

Re:Very old news. (1)

gedhrel (241953) | more than 4 years ago | (#32474602)

It is cool, but there's wiggle-room in the debate :-)

The device extracts energy from the wind, and using only that, the vehicle *as a whole* progresses downwind faster than the windspeed.

The cunning part is the prop; because it's rotating, the blades themselves aren't moving directly downwind (well, considered instantaneously, they're moving across it), and that's the "trick" of it. It's a very clever idea indeed.

Re:Very old news. (0)

Anonymous Coward | more than 4 years ago | (#32474796)

The cunning part is the prop; because it's rotating, the blades themselves aren't moving directly downwind (well, considered instantaneously, they're moving across it), and that's the "trick" of it. It's a very clever idea indeed.

Aha! I get it now. It must be a very light car or have very little wind resistance, for the props limited surface area to achieve this.

Mod parent up.

Re:Very old news. (4, Informative)

natehoy (1608657) | more than 4 years ago | (#32474706)

For sailors: By using a propeller rather than a sail, the "sail" this boat is using is simulating a continuous optimal downwind tack (the propeller blades are at a tack angle to the wind)

For cyclists: The wind is being turned into rotational force like the cranks on a bicycle. Since they now have rotational force, they can use gearing to take maximum advantage of that force.

Does that make it clearer?

Re:Very old news. (1)

SerpentMage (13390) | more than 4 years ago | (#32474454)

No this is not old news. I thought it was this trick as well. Its not. It the direct downwind problem, not side to wind problem.

Re:Very old news. (1)

Timmmm (636430) | more than 4 years ago | (#32474478)

Sailors can't go faster than the wind directly down-wind. From TFA which you didn't read:

Cavallaro explained the car is able to move faster than the wind because the propeller is not turned by the wind. The wind pushes the vehicle forward, and once moving the wheels turn the propeller. The propeller spins in the opposite direction to that expected, pushing the wind backwards, which in turn pushes the car forwards, turning the wheels, and thus turning the propeller faster still.

This isn't at all like sailing boats, or aerofoil-based boats.

Stupid exercise (-1)

Anonymous Coward | more than 4 years ago | (#32474312)

Boats have been doing this for about 100 centuries. They can travel against headwinds.

However, for anyone (Google) to invest good money in this technology marketing gimmick seems to be a bit nutty. Why are they wasting this money in this gimmick where there are real energy-related science and engineering problems that can be pursued?

Re:Stupid exercise (1)

thoughtsatthemoment (1687848) | more than 4 years ago | (#32474688)

Why are they wasting this money in this gimmick where there are real energy-related science and engineering problems that can be pursued?

Generally speaking, scientists who requested funding feel better when they get some results, any results.

Re:Stupid exercise (4, Insightful)

Goaway (82658) | more than 4 years ago | (#32474888)

Boats can not go downwind faster than the wind. Rather than jump out and try to announce to the world how much smarter you are than the people who actually did stuff, maybe you should first go read and comprehend what they actually did.

My Explanation (0)

Anonymous Coward | more than 4 years ago | (#32474378)

As other people have noted, this is a complete non-issue, sailors already do it, and there's no reason cars can't too.

I never really understood this for a long time, but the way I understand it is as follows:

Say you have a boat sailing straight downwind, it's going to go at a max of the speed of the wind.

Now consider a boat sailing at 45 degrees to the wind. Say travelling along the line y = x, and the wind's going along the x axis. The boat can potentially move at up to the speed of the wind in the x direction. But if it's moving diagonally, and at the speed of the wind along the x direction, it's going to be moving significantly faster (sqrt(2)) along the direction it's travelling.

This is all due to the friction of the water and that the boat travels more easily the way it's facing, which is similar for a vehicle. If there were no friction, the wind would just push the boat so it's side would be going first, but this obviously doesn't happen.

Re:My Explanation (1)

MichaelSmith (789609) | more than 4 years ago | (#32474422)

As other people have noted, this is a complete non-issue, sailors already do it, and there's no reason cars can't too.

"Land Yachts" are actually faster and more deadly than the version which travels on water because wheels have less rolling resistance (than moving through water) and they move across the wind with greater efficiency.

Re:My Explanation (1)

queazocotal (915608) | more than 4 years ago | (#32474512)

This is however substantially different to sailing.
Sailing uses an aerofoil with a high lift/drag ratio.

This works when the wind is not directly ahead of you.
When a sailboat - nomatter how advanced - tries to sail directly into the wind - it goes backwards.

This contraption however can go forward directly into a headwind.

(Indeed it wouldn't be as efficient on the water, as you would need a somewhat lossy water-screw too, instead of nice low-loss wheels - to act as the 'reference' for the 'differential'.

Re:My Explanation (1)

Goaway (82658) | more than 4 years ago | (#32474896)

As other people have noted, this is a complete non-issue, sailors already do it, and there's no reason cars can't too.

Those other people were just as wrong as you. This is about going directly downwind, not at an angle.

Why did you feel the need to say what they already said, and miss the point just as much as they already did?

Wind Powered Car? (0)

Anonymous Coward | more than 4 years ago | (#32474394)

Why don't we just put Keith Olbermann and Sean Hannity on opposite sides of this device? The pressure differential could power North and South America forever.

I have this pressing need to break the wind... (0)

Anonymous Coward | more than 4 years ago | (#32474418)

...powered record.

A million monkeys at a million keyboards... (4, Informative)

jtownatpunk.net (245670) | more than 4 years ago | (#32474428)

"The run should now settle the DWFTTW (downwind faster than the wind) debate that has been raging for some time on the Internet about whether or not such a feat was possible."

You're new to the internet, aren't you, son? No amount of reality can end an internet debate.

Gearbox analogy (1)

TeknoHog (164938) | more than 4 years ago | (#32474442)

From my understanding of the wheel-powered propeller system, this works basically like a gearbox that converts a lower RPM to higher. There is nothing unphysical about converting a lower velocity to a higher one this way.

Of course, in the gearbox analogy, the torque is lower in proportion, meaning less acceleration. Also, since the vehicle is now moving relatively against the wind, it needs power even to maintain that velocity.

Re:Gearbox analogy (0)

Anonymous Coward | more than 4 years ago | (#32474462)

when going against wind, the propellor spins in the opposite direction, so you just put the gearbox in reverse and still go forward.

No story here... move on... (0)

Anonymous Coward | more than 4 years ago | (#32474444)

Heck, I can fart and people move faster than the fart cloud. Thus, I have prior art and will file a claim of patent theft against Google, et al.

Another way to look at this. (4, Insightful)

queazocotal (915608) | more than 4 years ago | (#32474472)

Firstly, ignore that it's moving.
You have 0m/s ground, and a 10m/s wind.

You put up a wind turbine - it can extract power from this 10m/s difference.

The funky part of this idea is that this still works when you're moving faster than 10m/s.

For the moment - imagine that the turbine is a pure 'airscrew'.

It describes a helix in space - like the DNA molecule.
For every meter the air moves "forward" relative to it, it turns 1m clockwise.
Considering the air as completely rigid for the moment, the airscrew goes forward in a rigid helix, unchanged by load.

So - 10m/s wind - airscrew turns at 10m/s. Simple.
You can extract - say - 100N * 10m/s = 1kW of power.

Funky part coming up.

Now. You're moving at 20m/s. Twice as fast as the wind.
Of course this will slow you down - you can't use this to make power!

Well - not quite.

If you are moving at 20m/s in the direction of the wind - for a total speed with regards to the wind of
30m/s then the blades need to be spinning at 30m/s in order to keep up.

But, you can use gearing from the wheels so that the 'base' speed of this spin is 20m/s.

That is - when you push the car along on a windless day - the airscrew creates no drag - because it is spun at exactly the right speed by gearing from the wheels. It has effectively - by rotating at the right speed - cancelled out the movement of the car.

This cancellation then allows you to ignore the speed of the car, and instead work off the speed difference between the wind and ground!

In reality - it's very far from an airscrew, and turbines have a lot of drag. It's the same basic concept though.

Another beautiful and 'obvious' when you think of it bit of physics.

Joby Energy (0)

Anonymous Coward | more than 4 years ago | (#32474546)

I couldn't help but laugh.

Not sure about anywhere else, but Joby (or Jobby) in the UK is a slang term for the crap that comes out your behind.

That plus a car going faster than wind is pretty damn hilarious.

Re:Joby Energy (0)

Anonymous Coward | more than 4 years ago | (#32474920)

I have lived in the UK for seven years and have never heard this.

Which probably means it's a saying in the backwaters of Lincolnshire and hence nobody cares.

But not in the same direction as the wind (0)

Anonymous Coward | more than 4 years ago | (#32474606)

Yawn. Listen, call me back when you get it to go twice as fast - in the same direction as the wind. Using the rather vague, "down wind" isn't fooling anyone.

Re:But not in the same direction as the wind (1)

Goaway (82658) | more than 4 years ago | (#32474902)

That is exactly what they did.

Re:But not in the same direction as the wind (0)

Anonymous Coward | more than 4 years ago | (#32474982)

ring, ring.

hi?

is this "moron"?

Yes this is directly in the same direction as the wind,
there are no "angles" (tacking).

Read it, then try and understand it.

if you can't then as questions, but dismissing it out of hand shows
then not only you do not understand, but that you are so dumb
you want to continue not understanding, and also want to try
to prevent anyone else from understanding.

Not impressed (5, Funny)

thoughtsatthemoment (1687848) | more than 4 years ago | (#32474636)

Let me know when you have a solar powered car traveling faster than light.

The Oracle Trimaran..250% faster than the wind... (3, Informative)

droopus (33472) | more than 4 years ago | (#32474638)

The Oracle trimaran [bmworacleracing.com] that recently won the America's Cup had no problem exceeding wind speed due to aerodynamics, and the insanely cool carbon fiber wing that added to sail volume and power, and allowed them to use a fixed-shape sail - a huge advantage. They had no problem sailing between 16 and 24 knots upwind in 5 to 10 knots of wind—that’s 2.5 times wind speed.

They went even quicker periodically, and had a five knot downwind advantage. The first race report [boats.com] shows that the Oracle trimaran was able to almost constantly fly both outer and center hulls (amazing on a boat this big.,.I sail Hobies [hobiecat.com] and this shit is HARD) and execute some slick pre-race maneuvers (which is how you really win sailing races).

So yes, sailboats have been exceeding wind speed for a while, but not by 250%..until now. When a car does that, I'll be impressed.

Re:The Oracle Trimaran..250% faster than the wind. (0)

Anonymous Coward | more than 4 years ago | (#32474850)

Land vehicles have been exceeding the speed of wind for quite some time also. The difference here is that this vehicle will exceed the speed of wind while moving directly downwind.

Apparent Wind (1)

Bob9113 (14996) | more than 4 years ago | (#32474674)

Consider the apparent wind, not the actual wind.

When a sailboat or iceboat is sailing across the wind (beam reach), the apparent wind (the velocity of wind relative to the sail) diminishes more slowly than the velocity of the vessel increases. This is why it is possible for a vessel on a reach to exceed the surface-relative wind velocity.

When a sailboat, iceboat, or hoax travels directly downwind, the apparent wind is equal to the velocity of the wind minus the velocity of the vessel. The force imparted on the vessel by the wind is related to the sail area times that apparent velocity. When the vessel is traveling at the same surface-relative velocity as the wind, the apparent wind drops to zero and the force imparted on the vessel drops to zero. No amount of gearing can multiply a force of zero to make it greater than zero.

http://en.wikipedia.org/wiki/Apparent_wind [wikipedia.org]

To come at this from a slightly different direction, consider that propellers are not terribly efficient thrust producing devices. Ground cars do not use propellers (except for novelty purposes) because it is more efficient to use tires, which have higher efficiency (or metal wheels in the case of trains, which are better still on a very smooth surface). Suppose that instead of confusing things by adding a propeller, they claimed that they had one set of wheels being turned by the wind-powered forward motion of the vehicle. They then had a gear train running from those "power" wheels and connected to a set of "drive" wheels. They claimed that the wind power pushing the vehicle forward caused the "power" wheels to spin, to turn the gear train, and hence to spin the "drive" wheels faster than the power wheels -- propelling the vehicle forward.

If you would not believe the two-sets-of-wheels design, you should not believe this one.

In short, this did not happen. The vehicle did not reach steady state direct downwind travel above the ground-relative velocity of the wind.

Re:Apparent Wind (1)

Goaway (82658) | more than 4 years ago | (#32474910)

In short, this did not happen. The vehicle did not reach steady state direct downwind travel above the ground-relative velocity of the wind.

You are incorrect. It did just this.

Explanation (1)

Alsee (515537) | more than 4 years ago | (#32474732)

I think I can give a pretty good explanation how this works.

Let's start at the point where the vehicle is going at exact the same speed as the wind. The propeller is seeing exactly zero wind speed. Now look to the wheels and their link to the ground. Lets put a 100 pound load on the wheels, a force acting to slow the vehicle down. This supplies us power to drive the propeller. So now we have a 100 pound rotary force to spin the propeller. The propeller has a lift-to-drag-ratio greater than 1. 100 pounds of rotary force spins the propeller up until the drag equals 100 pounds. The propeller spinning at this rate generates more than 100 pounds of thrust. The first 100 pounds of thrust balances out against the 100 pound load on the wheels, and the remaining thrust accelerates the vehicle.

There is no energy violation going on because we are extracting energy from the difference between wind speed and ground speed. When the vehicle is moving faster than the wind the wind is still pushing forwards on the backwash air from the propeller, that backwash air from the propeller is pushing forwards on the propeller, and the propeller is pushing the vehicle forwards against the ground. We have a chain of forces where the wind is in effect pushing forwards against the ground, and we extract that wind-to-ground force to accelerate the vehicle. That wind-vs-ground energy source exists no matter what speed the vehicle is traveling. We can use that energy to accelerate the vehicle up to ANY speed, either upwind or downwind, and we are limited only by energy losses to friction and drag.

When the wind stops the energy supply stops. The vehicle will then slow due to friction and drag.

-

Re:Explanation (1)

Alsee (515537) | more than 4 years ago | (#32474972)

I think I explained part of that badly.

We'll assume vehicle speed is twice the wind speed. We'll imagine a 1 second period where the wind moves forwards 100 feet and the vehicle moves forwards 200 feet. Work is a force through a distance. The wheels are seeing 100 pounds of force through 200 feet of ground travel. The propeller is experiencing 100 pounds of force, but the propeller only moves 100 feet relative to the air. The wheels are doing twice as much work (and producing double the power) than the propeller is consuming. Again the energy is coming from the difference between wind and ground speeds. The energy of the wind relative to the ground is being extracted.

-

It's gonna be fun watching those (1)

BubbaDave (1352535) | more than 4 years ago | (#32474814)

watching those who know how simple the principle is and know it *can* work try and convince those who know it *can't* work.

Dave

imagine a bike that goes faster peddle speed ... (0)

Anonymous Coward | more than 4 years ago | (#32474824)

There was really a debate?

Attach a big propeller, and gear up (mechanically or electrically).

Conservation (1)

jklovanc (1603149) | more than 4 years ago | (#32474842)

lets look at a specific state.

If the wind is directly behind the vehicle and the vehicle is travelling at exactly the speed of the wind the wind speed relative to the vehicle would be 0.
Since it takes power from the forward momentum of the vehicle to turn the propeller that would cause the vehicle to slow down.
The propeller would push against the air with a most the same force as supplied by the wheels causing the energy to be put back into the momentum of the vehicle at most bringing the speed back up to the original speed.
To accelerate the vehicle would require additional energy from somewhere. At 0 relative wind speed where does that additional energy come from?

Does NOT disprove that the wind speed is the limit (0)

Anonymous Coward | more than 4 years ago | (#32474882)

Although the average wind speed is 13.5mph, this is obviously an average. It is clear that individual wind molecules can travel faster than this, whilst others travel slower, for an average of 13.5mph. If the vehicle is light enough, it is not impossible that this sprinkling of ultrafast wind molecules can push it. However, the upper speed limit is the volume of solid-form wind molecules at any given speed (or faster) that exist to transfer their momentum to the vehicle.

Not convinced by treadmill demo (1)

psb777 (224219) | more than 4 years ago | (#32474950)

The revolutionary claim is that a vehicle powered only by the wind can travel downwind faster than the wind. When they put the model on the treadmill and it fights it's way uphill it is NOT going faster than the wind. There still is a tailwind from the vehicle's perspective. So, I know not if the feat is possible, I just know that it is not demonstrated by the model on the treadmill. Interesting claim, bad experiment.

the propeller is going backwards? (1)

pedantic bore (740196) | more than 4 years ago | (#32474986)

If the cart is going directly downwind faster than the wind, then the apparent wind (the velocity of the air relative to the cart) is backwards. So, as the cart accelerates from slower than the wind to faster than the wind, why doesn't the propeller change direction? Shouldn't it be going "backwards"?

In any case, if this does turn out to not be a hoax, I think that the inventor in the video should thank his lucky stars that the wind happened to be blowing in exactly the same direction as the street in front of his house, because the experiment is void if the wind is at a slightly different angle (tacking downwind faster than the wind is no big deal), and what are odds of that?

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