Unfortunately, "literally" can literally mean "metaphorically." It's in the dictionary.
I believe this is a little trick linguists have snuck in, almost as if to say "Language is not mathematics (and this will really piss off the slashdot crowd, who like both and will go nuts trying to reconcile the two!)"
"Literal" meaning "metaphorical" is also a literal irony, which is another thing that excites linguists. I think once you get the joke, it won't be so bothersome.
If there were a missing persons industry, then we could assign an imaginary and excessive value to "loss of profits" due to missing persons. Then they could be considered as valuable as a CD, and the FBI could put more effort into investigating.
I have something very important to say to that. Here goes:
XXX X XXXXXX XX XX XXXXX XXXX XXXX. XX X XXXXX XXXXX XXXXX your mom XXXXXX. XXXXX XXXXX X XX XXXX XX XXX XXX XXXX XX XXXXX XXXX. XXX XXXX XX XXXXX! XXX XXXX XXX XXXXXX XX X XXXX X XXXX XXXXXX XXX XXXX XXXX XX XXX XXXXX XX XXX XXXXXXX XXXXX XXX XXXXX XX XXX XXXXX XXX XXX XXXXX XXXXXXXXX. XXXXXXX XX XXXXXXX XX XXXXX XXXXXXX XXXXXX a big XXXXXX XXXXX XX XXXXX XXXXX XXXXXXXX XXXX XXXXXX XXX X XXXXXXXX up my XXXXXXX XXXXX XXXX X XXX XXXXX XXX XXXXXXX XXXXX XXX.
Note: This comment was edited to save people the trouble of bothering with unnecessary replies. You're welcome!
Whether or not it's acceptable to have the criminally perverted working in the pentagon, I think it's discouraging to have people that dumb working in critical positions. How can people in high-security positions be that clueless about what information is available about them?
Re:Requires Silverlight? Yeah you can shove that
on
Recomputing the Sky
·
· Score: 1
Yeah, a company using their own product is a sure sign of desperation.
Yes, they used their own product, and they used Linux software too [citation needed]. Funny, they mention how they did it with the help of Microsoft assets, but they didn't mention the Linux stuff. This "story" contains ads for "microsoft HPC assets", for xbox 360 (it's so subtle you may have missed it), and for Silverlight.
But it's not that they're tooting their own horn enough to make them blind, it's that they're using this to push a product that nobody wants.
GS steals a car from Customer A, picks up Customer B and pays for sex, but then beats up B and takes the money back, sells a sex tape it made with B to A, then runs down A with their own car.
"A couple lefties at work" are hardly an authority on the topic. They sound as misinformed at the righties in the AGW debates. Unfortunately the misinformed righties who keep insisting that man has no impact on any and all climate change are treating themselves as authorities. People who want to believe the extremists (in either direction) will accept them as authorities, which is a dangerous situation.
It's easy to find people who aren't extremists... most people aren't. Moderates tend not to spend as much time and vocal energy debating it as extremists do, so if you only look at who's doing the talking, you're more likely to find extremists.
He'll wire stadium concert speakers aimed at the ground, to hundreds of car stereo sound-off contest systems, step up real close to the mic, breathe in deeply, and in a deep booming voice say, "I HAVE NOTHING TO ANNOUNCE."
Okay that last one nearly did me in, but this is too interesting to give up on. I admit, you're right and I was wrong with my explanation. I'm forced to change my story of how it works. This makes it harder to grasp mentally, but it jives with what you wrote and with the quotes the builders give in TFA.
First though: No fair ending an argument using decoupling, because if you remove any aspect of how the device works, it won't work. Also no fair discounting the effect of the wind (at any vehicle speed), because without the wind there is no energy input, and then this becomes like trying to argue that a perpetual motion machine works, which is impossible. At all times, the vehicle is gaining energy from the 13.5 mph wind (and losing energy to a host of inefficiencies). And yes, we're not talking about tacking or rotational kinetic energy or any stuff that's not used in this vehicle.
If the wind and the vehicle are moving at the same speed then there is no wind at all. In order for the prop to be in the "effortless" state it has to not be moving. That is consider the prop on a non-moving, windless day. If it is moving then it will be pushing on the air and that takes energy.
Yes, that actually seems to be the case that is happening. It IS fair to look at it from the moving frame where the vehicle and wind are moving at the same rate, which is admittedly puzzling. However if you assume that it's a windless day and the vehicle is not moving, then you must also allow that there is a moving road, or a conveyor underneath you, that you can extract energy from. That just makes things confusing.
But alright, say we do that. Say we're stationary on a windless day, and have a conveyor moving at 13.5 mph under us, and we're using that to turn the prop, which is pushing air backward. This provides a forward force. Now let's slowly move from this frame to a different frame. To start, the conveyor is moving backward, the vehicle is stationary, there's no wind, and the prop is pushing air backward and providing a small forward force. Now say we add a small velocity to the entire frame... a tiny tail wind with velocity v, and we have the vehicle moving forward at velocity v as well, and the conveyor speed has changed by v. The backward-moving conveyor has slowed down, however the relative speed of the vehicle to the conveyor is still the same as it was, so it can still extract the same energy to use to move the prop and push the air, providing the the same forward force. There is still no wind relative to the vehicle. Everything is the same, which is expected... we're basically just changing frame of reference.
Now repeat until we get to a fixed frame. The tail wind is 13.5 mph, the vehicle is moving 13.5 mph, the conveyor is not moving, and there is still no wind relative to the vehicle. It is still extracting the same energy from the conveyor/road, and turning it into a forward force. And so the vehicle accelerates.
The missing piece here is that while the difference in wind/road speed (the "conveyor") is *free*, it's not that *easy*. The car is light, and by necessity it needs to be easily accelerated, so we can't let it be fixed in position in any way. If we extract energy from the conveyor, it will pull on us, and by law I think the backward force from extracting energy needs to be greater than any forward force that we can create by using only that energy??? However, in our moving frame, we still also have the resistive force of the propeller acting as a sail, acting counter to the backward pull of the conveyor/road. Okay admittedly this isn't very intuitive, but this force would have to be significant, because this is the only way the vehicle extracts energy from the wind... it must be enough to both accelerate the vehicle forward, AND overcome all the inefficiencies and drag in the entire system.
Yes, when at vehicle speeds equal to the wind (or greater, I would guess) this force isn't so much using the wind to accelerate the ca
consider taking 1 unit of kinetic energy away from the car due to the load of the crank shaft on the wheel [...] Your job is to use that 1 unit of kinetic energy to cause the car's speed to increase by more than 1 unit of kinetic energy.
No, that's not how this car works. The energy from the wheels is basically used to make the propeller cut through the air as efficiently as possible. If there was no wind it wouldn't be pushing on any air at all, at any car speed. With a 13.5 mph tailwind, it is using the same energy it requires to push NO AIR AT ALL, but there is an additional 13.5 mph tailwind pushing on it (at any car speed). I explained this better here: http://slashdot.org/comments.pl?sid=1676544&cid=32481608
So the prop always feels a tailwind, even though the car feels a stronger headwind. The car isn't sapping energy from the wheels to move the prop; the TAILWIND is also helping to move the prop. The net energy transfer is from the movement of air to the movement of the vehicle, not the other way around.
Sorry if this is redundant but I see a LOT of posts saying it's impossible and a LOT of explanations of why it is but that have nothing to do with the setup described in the article. Here is a relatively simple explanation:
Imagine an efficient, aerodynamic vehicle with a very big propeller on it. Imagine the vehicle is moving at some arbitrary speed down a very smooth level road. If the propeller isn't moving fast enough, it will cause a lot of drag against its front side. If it is moving fast enough, it will push air backward and propel the vehicle forward.
Now imagine the propeller is mechanically linked to the wheels so that at any arbitrary speed, it is neither moving slow enough to cause drag against its front side, nor fast enough to create a forward force. Instead, all it is doing is cutting through the air as efficiently as possible. In this case, it takes very little energy to keep it going. It is cutting through the air like the spokes of a bicycle, not pushing the air around like a ceiling fan.
Imagine our vehicle moving at 10 kph forward on a windless day. The air is moving like a 10 kph headwind relative to the vehicle. However, because the propeller is cutting through the air, rather than being dragged by it or pushing it, it is as if the wind is moving at 0 kph relative to the propeller.
Now imagine that the vehicle is moving 10 kph with a 10 kph tail wind. The air is no longer moving at all relative to the vehicle. The propeller which was slicing effortlessly through the air with a 10 kph headwind, now has an extra 10 kph relative wind at its back, pushing both forward on the propeller and pushing it around faster (returning some energy to the wheels as forward drive).
Likewise, if the vehicle is moving at 50 kph with a 10 kph tail wind, the propeller which would slice effortlessly through a 50 kph relative headwind, would feel an extra 10 kph relative tailwind as it cuts into the 40 kph relative headwind.
If the prop is tuned to cut perfectly through the relative headwind that is opposite the vehicle's velocity relative to the ground, then regardless of the speed the vehicle is moving, the propeller will always "feel" the windspeed as it is relative to the ground.
If the vehicle is built efficiently enough, the energy gained from the constant 10 kph tail wind against the propeller could be greater than energy lost through vehicle drag, friction, mechanical inefficiencies, and propeller drag, and the vehicle could accelerate faster than the speed of the tailwind, until it reaches a speed where the energy gained and lost balance each other out.
Me again... after RTFA a bit more. My last comments were unhelpful.
If you do everything right the force*time =momentum push gained from the air exactly offsets the momentum loss from the wheels
If you do everything right (IE if it's a perpetual motion machine) then the energy gained from the wheels against the road exactly matches the energy put into pushing backward against the air. However, you're pushing against air that is traveling 13.5 mph slower than the road is. If the extra energy you can gain from the faster-moving road is greater than the energy lost in the inefficiency of the system, then you can accelerate.
Another way to wrap our heads around this is this: Say it IS a perpetual motion machine moving 38.5 mph against NO wind. Say the wheels move the propeller with perfect efficiency, and the prop cuts through the air with NO drag. This means that the propeller is not pushing against any air -- it's turning at the right speed so that there's no drag on its front side, and it's not pushing any air against its back side.
Now add in a 13.5 mph wind at your back. The prop that was slicing perfectly through the air at an air speed of 38.5 mph, now has a force being applied to its back at an air speed of 25.5 mph, equal to a 13.5 mph wind at your back. Though the vehicle is traveling faster than the wind, the propeller "feels" a 13.5 mph wind at its back.
Of course, the efficiencies aren't 100% and the energy gained from that 13.5 mph wind balances out energy lost, apparently at around 38.5 mph for the test vehicle they built.
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.
Okay when I read that I thought they must have got it wrong, because that makes no sense WRT all the "angle of propeller as a sail" -type arguments for how this works, found here in various comments.
But here's how this can work...
First, imagine that this IS a perpetual motion machine and that there's NO wind. Imagine that the vehicle is (by pushing it) traveling at 30 kph, which turns the wheels, and that the wheels are turning the prop, pushing air backwards. Imagine that there's no friction, no loss in the mechanical systems, and no loss in the prop pushing the air. This is impossible of course, but if all the energy obtained from turning the wheel against the ground was put into pushing the vehicle forward, with 100% efficiency, the car would continue to move forward at 30 kph.
Now imagine that you're heading at 30 kph, downwind with a 10 kph wind. The road beneath you is moving at 30 kph, but you're pushing into a wind that is moving at 20 kph relative to you. So if you could sustain your speed with a 100%-efficient perpetual motion machine moving relatively 30 kph into the wind, you would be able to *gain* a bit of energy against a 20 kph wind (the energy is gained from the speed of the wind relative to the road), and you could accelerate.
Of course, 100% efficiency is not possible. Thus the car has to be built ultralight, everything has to be ultra-efficient, and still the acceleration you get will be small. And as you travel faster, the inefficiencies of the system are likely to be greater. But for the test vehicle they built, at the speeds they were going, that 13.5 mph wind meant that they were pushing against air using a moving road that was traveling 13.5 mph faster than the air, which balanced out the inefficiencies of the system at a speed of about 38.5 mph.
Slashdot Mirror
Unfortunately, "literally" can literally mean "metaphorically." It's in the dictionary.
I believe this is a little trick linguists have snuck in, almost as if to say "Language is not mathematics (and this will really piss off the slashdot crowd, who like both and will go nuts trying to reconcile the two!)"
"Literal" meaning "metaphorical" is also a literal irony, which is another thing that excites linguists. I think once you get the joke, it won't be so bothersome.
Maybe the MPIA (Missing Persons Industry Association) has lobbied for decreased FBI investigations, to protect those profits.
If there were a missing persons industry, then we could assign an imaginary and excessive value to "loss of profits" due to missing persons. Then they could be considered as valuable as a CD, and the FBI could put more effort into investigating.
... information wants to XX XXXX.
I have something very important to say to that. Here goes:
XXX X XXXXXX XX XX XXXXX XXXX XXXX. XX X XXXXX XXXXX XXXXX your mom XXXXXX. XXXXX XXXXX X XX XXXX XX XXX XXX XXXX XX XXXXX XXXX. XXX XXXX XX XXXXX! XXX XXXX XXX XXXXXX XX X XXXX X XXXX XXXXXX XXX XXXX XXXX XX XXX XXXXX XX XXX XXXXXXX XXXXX XXX XXXXX XX XXX XXXXX XXX XXX XXXXX XXXXXXXXX. XXXXXXX XX XXXXXXX XX XXXXX XXXXXXX XXXXXX a big XXXXXX XXXXX XX XXXXX XXXXX XXXXXXXX XXXX XXXXXX XXX X XXXXXXXX up my XXXXXXX XXXXX XXXX X XXX XXXXX XXX XXXXXXX XXXXX XXX.
Note: This comment was edited to save people the trouble of bothering with unnecessary replies. You're welcome!
Whether or not it's acceptable to have the criminally perverted working in the pentagon, I think it's discouraging to have people that dumb working in critical positions. How can people in high-security positions be that clueless about what information is available about them?
Yeah, a company using their own product is a sure sign of desperation.
Yes, they used their own product, and they used Linux software too [citation needed]. Funny, they mention how they did it with the help of Microsoft assets, but they didn't mention the Linux stuff. This "story" contains ads for "microsoft HPC assets", for xbox 360 (it's so subtle you may have missed it), and for Silverlight.
But it's not that they're tooting their own horn enough to make them blind, it's that they're using this to push a product that nobody wants.
*cough*troll*cough*
Do you have a case of cough due to trolled?
[ ] Microsoft killed my family and made me watch, but the video required Silverlight
Mommy, why is the sky flashing red?
Back before you were born, dear, the sky worked reliably. Like Super Mario Brothers on 1985-era Nintendo consoles.
It's true, the FBI takes terrorist child porn quite seriously.
Instead, tell them that the IP address has links to Al Qaeda and has WMDs. You might not get your laptop back, but you're sure to be re-elected.
(Score:2, Current)
Yes: Napster.
Napster was a success due to piracy. It failed due to RIAA.
RIAA is costing billions in lost revenue and billions of lots jobs. Therefore they should be sued for trillions.
Can you put this in car terms?
GS steals a car from Customer A, picks up Customer B and pays for sex, but then beats up B and takes the money back, sells a sex tape it made with B to A, then runs down A with their own car.
easily a few thousand feet wide and high.
How many Library of Congresses would fit inside this mountain?
THE BURDEN IS ON YOU TO MAKE ME READ IT, YOU ASSHOLES!!!!!!!
just kidding
"But dicks also fuck assholes"
less caps less caps less caps
"A couple lefties at work" are hardly an authority on the topic. They sound as misinformed at the righties in the AGW debates. Unfortunately the misinformed righties who keep insisting that man has no impact on any and all climate change are treating themselves as authorities. People who want to believe the extremists (in either direction) will accept them as authorities, which is a dangerous situation.
It's easy to find people who aren't extremists... most people aren't. Moderates tend not to spend as much time and vocal energy debating it as extremists do, so if you only look at who's doing the talking, you're more likely to find extremists.
I like it! It reads like Fitter, Happier.
Slashdot ate my first reply where I commented on that.
I agree that 1729 will be rather a dull one.
I'm waiting for Ta(7) though.
(thus proving that I know how to look up shit in wikipedia)
Yet one more thing to fear.
At least now it makes sense why we're not allowed to bring liquids on planes.
Report your neighbor to the local homeland security office if you suspect he may be drinking unpatriotic isotopes.
He'll wire stadium concert speakers aimed at the ground, to hundreds of car stereo sound-off contest systems, step up real close to the mic, breathe in deeply, and in a deep booming voice say, "I HAVE NOTHING TO ANNOUNCE."
... is an ad for a printer that doesn't print spam.
Okay that last one nearly did me in, but this is too interesting to give up on. I admit, you're right and I was wrong with my explanation. I'm forced to change my story of how it works. This makes it harder to grasp mentally, but it jives with what you wrote and with the quotes the builders give in TFA.
First though: No fair ending an argument using decoupling, because if you remove any aspect of how the device works, it won't work. Also no fair discounting the effect of the wind (at any vehicle speed), because without the wind there is no energy input, and then this becomes like trying to argue that a perpetual motion machine works, which is impossible. At all times, the vehicle is gaining energy from the 13.5 mph wind (and losing energy to a host of inefficiencies). And yes, we're not talking about tacking or rotational kinetic energy or any stuff that's not used in this vehicle.
If the wind and the vehicle are moving at the same speed then there is no wind at all. In order for the prop to be in the "effortless" state it has to not be moving. That is consider the prop on a non-moving, windless day. If it is moving then it will be pushing on the air and that takes energy.
Yes, that actually seems to be the case that is happening. It IS fair to look at it from the moving frame where the vehicle and wind are moving at the same rate, which is admittedly puzzling. However if you assume that it's a windless day and the vehicle is not moving, then you must also allow that there is a moving road, or a conveyor underneath you, that you can extract energy from. That just makes things confusing.
But alright, say we do that. Say we're stationary on a windless day, and have a conveyor moving at 13.5 mph under us, and we're using that to turn the prop, which is pushing air backward. This provides a forward force. Now let's slowly move from this frame to a different frame. To start, the conveyor is moving backward, the vehicle is stationary, there's no wind, and the prop is pushing air backward and providing a small forward force. Now say we add a small velocity to the entire frame... a tiny tail wind with velocity v, and we have the vehicle moving forward at velocity v as well, and the conveyor speed has changed by v. The backward-moving conveyor has slowed down, however the relative speed of the vehicle to the conveyor is still the same as it was, so it can still extract the same energy to use to move the prop and push the air, providing the the same forward force. There is still no wind relative to the vehicle. Everything is the same, which is expected... we're basically just changing frame of reference.
Now repeat until we get to a fixed frame. The tail wind is 13.5 mph, the vehicle is moving 13.5 mph, the conveyor is not moving, and there is still no wind relative to the vehicle. It is still extracting the same energy from the conveyor/road, and turning it into a forward force. And so the vehicle accelerates.
The missing piece here is that while the difference in wind/road speed (the "conveyor") is *free*, it's not that *easy*. The car is light, and by necessity it needs to be easily accelerated, so we can't let it be fixed in position in any way. If we extract energy from the conveyor, it will pull on us, and by law I think the backward force from extracting energy needs to be greater than any forward force that we can create by using only that energy??? However, in our moving frame, we still also have the resistive force of the propeller acting as a sail, acting counter to the backward pull of the conveyor/road. Okay admittedly this isn't very intuitive, but this force would have to be significant, because this is the only way the vehicle extracts energy from the wind... it must be enough to both accelerate the vehicle forward, AND overcome all the inefficiencies and drag in the entire system.
Yes, when at vehicle speeds equal to the wind (or greater, I would guess) this force isn't so much using the wind to accelerate the ca
RIAA Sues Pet-Owners for $250 Trillion
RIAA Sues Earth for $3.3 Quintillion
http://postpicayune.blogspot.com/2010/06/this-week-in-news.html
consider taking 1 unit of kinetic energy away from the car due to the load of the crank shaft on the wheel [...] Your job is to use that 1 unit of kinetic energy to cause the car's speed to increase by more than 1 unit of kinetic energy.
No, that's not how this car works. The energy from the wheels is basically used to make the propeller cut through the air as efficiently as possible. If there was no wind it wouldn't be pushing on any air at all, at any car speed. With a 13.5 mph tailwind, it is using the same energy it requires to push NO AIR AT ALL, but there is an additional 13.5 mph tailwind pushing on it (at any car speed). I explained this better here: http://slashdot.org/comments.pl?sid=1676544&cid=32481608
So the prop always feels a tailwind, even though the car feels a stronger headwind. The car isn't sapping energy from the wheels to move the prop; the TAILWIND is also helping to move the prop. The net energy transfer is from the movement of air to the movement of the vehicle, not the other way around.
Sorry if this is redundant but I see a LOT of posts saying it's impossible and a LOT of explanations of why it is but that have nothing to do with the setup described in the article. Here is a relatively simple explanation:
Imagine an efficient, aerodynamic vehicle with a very big propeller on it. Imagine the vehicle is moving at some arbitrary speed down a very smooth level road. If the propeller isn't moving fast enough, it will cause a lot of drag against its front side. If it is moving fast enough, it will push air backward and propel the vehicle forward.
Now imagine the propeller is mechanically linked to the wheels so that at any arbitrary speed, it is neither moving slow enough to cause drag against its front side, nor fast enough to create a forward force. Instead, all it is doing is cutting through the air as efficiently as possible. In this case, it takes very little energy to keep it going. It is cutting through the air like the spokes of a bicycle, not pushing the air around like a ceiling fan.
Imagine our vehicle moving at 10 kph forward on a windless day. The air is moving like a 10 kph headwind relative to the vehicle. However, because the propeller is cutting through the air, rather than being dragged by it or pushing it, it is as if the wind is moving at 0 kph relative to the propeller.
Now imagine that the vehicle is moving 10 kph with a 10 kph tail wind. The air is no longer moving at all relative to the vehicle. The propeller which was slicing effortlessly through the air with a 10 kph headwind, now has an extra 10 kph relative wind at its back, pushing both forward on the propeller and pushing it around faster (returning some energy to the wheels as forward drive).
Likewise, if the vehicle is moving at 50 kph with a 10 kph tail wind, the propeller which would slice effortlessly through a 50 kph relative headwind, would feel an extra 10 kph relative tailwind as it cuts into the 40 kph relative headwind.
If the prop is tuned to cut perfectly through the relative headwind that is opposite the vehicle's velocity relative to the ground, then regardless of the speed the vehicle is moving, the propeller will always "feel" the windspeed as it is relative to the ground.
If the vehicle is built efficiently enough, the energy gained from the constant 10 kph tail wind against the propeller could be greater than energy lost through vehicle drag, friction, mechanical inefficiencies, and propeller drag, and the vehicle could accelerate faster than the speed of the tailwind, until it reaches a speed where the energy gained and lost balance each other out.
Me again... after RTFA a bit more. My last comments were unhelpful.
If you do everything right the force*time =momentum push gained from the air exactly offsets the momentum loss from the wheels
If you do everything right (IE if it's a perpetual motion machine) then the energy gained from the wheels against the road exactly matches the energy put into pushing backward against the air. However, you're pushing against air that is traveling 13.5 mph slower than the road is. If the extra energy you can gain from the faster-moving road is greater than the energy lost in the inefficiency of the system, then you can accelerate.
Another way to wrap our heads around this is this: Say it IS a perpetual motion machine moving 38.5 mph against NO wind. Say the wheels move the propeller with perfect efficiency, and the prop cuts through the air with NO drag. This means that the propeller is not pushing against any air -- it's turning at the right speed so that there's no drag on its front side, and it's not pushing any air against its back side.
Now add in a 13.5 mph wind at your back. The prop that was slicing perfectly through the air at an air speed of 38.5 mph, now has a force being applied to its back at an air speed of 25.5 mph, equal to a 13.5 mph wind at your back. Though the vehicle is traveling faster than the wind, the propeller "feels" a 13.5 mph wind at its back.
Of course, the efficiencies aren't 100% and the energy gained from that 13.5 mph wind balances out energy lost, apparently at around 38.5 mph for the test vehicle they built.
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.
Okay when I read that I thought they must have got it wrong, because that makes no sense WRT all the "angle of propeller as a sail" -type arguments for how this works, found here in various comments.
But here's how this can work...
First, imagine that this IS a perpetual motion machine and that there's NO wind. Imagine that the vehicle is (by pushing it) traveling at 30 kph, which turns the wheels, and that the wheels are turning the prop, pushing air backwards. Imagine that there's no friction, no loss in the mechanical systems, and no loss in the prop pushing the air. This is impossible of course, but if all the energy obtained from turning the wheel against the ground was put into pushing the vehicle forward, with 100% efficiency, the car would continue to move forward at 30 kph.
Now imagine that you're heading at 30 kph, downwind with a 10 kph wind. The road beneath you is moving at 30 kph, but you're pushing into a wind that is moving at 20 kph relative to you. So if you could sustain your speed with a 100%-efficient perpetual motion machine moving relatively 30 kph into the wind, you would be able to *gain* a bit of energy against a 20 kph wind (the energy is gained from the speed of the wind relative to the road), and you could accelerate.
Of course, 100% efficiency is not possible. Thus the car has to be built ultralight, everything has to be ultra-efficient, and still the acceleration you get will be small. And as you travel faster, the inefficiencies of the system are likely to be greater. But for the test vehicle they built, at the speeds they were going, that 13.5 mph wind meant that they were pushing against air using a moving road that was traveling 13.5 mph faster than the air, which balanced out the inefficiencies of the system at a speed of about 38.5 mph.