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BrianCunningham | Can you go downwind faster than the wind? | ||
Senior Guru
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someone just did it in a wind powered car
http://jalopnik.com/5556198/wind+powe ... -internet-naysayers-wrong |
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Posted on: 2010/7/6 4:00
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CentralCoaster | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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But you gotta time those overpasses just right...
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Posted on: 2010/7/6 6:40
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TommyT-Bone | Re: Can you go downwind faster than the wind? | ||
Chair-man of the bored
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One big drawback. It won't fit in the garage.
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Posted on: 2010/7/6 11:43
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CentralCoaster | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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How do you get it started? The prop is driven by headwind... but you don't have any headwind until vehicle speed exceeds wind speed.
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Posted on: 2010/7/7 0:06
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BillH | Re: Can you go downwind faster than the wind? | ||
The Stig Moderator
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There's a big rubberband inside of it.
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Posted on: 2010/7/7 0:58
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BrianCunningham | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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downwind
the wind is directly behind you. |
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Posted on: 2010/7/7 0:59
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CentralCoaster | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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With what, a huge sail? Or maybe they can pivot the blades like the do on the wind farms... use tail wind to drive the turbine up to a certain point, then pivot the blades to take advantage of the headwind. But then you have that dead spot where the car is travelling the same speed as the wind... what accelerates it then? Battery power generated from the turbine at park? That would be cheating.
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Posted on: 2010/7/7 1:10
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BrianCunningham | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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you didn't read the article did you?
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Posted on: 2010/7/7 1:17
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Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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MK 82 | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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Probably felt bad about doing it at work.
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Posted on: 2010/7/7 3:21
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CentralCoaster | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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I read it more carefully this time around but it does not address the issues I brought up. If it's propelled by the headwind (relative to vehicle speed) then it how does it get past 13 mph? And how does it store enough power below 13 mph to get past that threshold?
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Posted on: 2010/7/7 3:21
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BrianCunningham | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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tailwind, not headwind
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Posted on: 2010/7/7 19:23
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Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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CentralCoaster | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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That tailwind becomes a headwind when you go faster than it! Oh nevermind already...
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Posted on: 2010/7/7 20:44
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biggrizzly | Re: Can you go downwind faster than the wind? | ||
2011 Memorial Day Car Show Winner!
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Tailwind never becomes headwind. It will always be blowing at 13mph from the rear. (sailors knowledge) What you feel in your face is called apparent wind and that is from you and the vehicle moving through the air. I guess this is where friction and drag is most important in these designs, the less drag the less friction from apparent wind. There are a few new sailboats out there that are breaking all kinds of wind speed records now using similar technologies. I find it interesting and need to do a little researchin' Also a sailboat moves through the water by utilizing airfoils more than using tailwinds. My boat will sail faster on a reach (wind coming from the either port or starboard side at about 45% to the direction of travel)than with a tailwind.
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Posted on: 2010/7/7 23:00
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CentralCoaster | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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Dammit Jim, I'm an engineer, not a sailor.
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Posted on: 2010/7/7 23:06
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biggrizzly | Re: Can you go downwind faster than the wind? | ||
2011 Memorial Day Car Show Winner!
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Quote:
Well after re-reading their article and digging a little deeper, they are not using any sailing theory as they say it gets too complicated, especially "wind coming from the side"(their words). They are just going on tailwind, momentum and I guess kinetic energy that gets stored when the prop turns. Its really fuzzy how they "gear" the prop and get the mechanical energy to the wheels. I'd like to see a real detail article about how they accomplished this. |
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Posted on: 2010/7/7 23:20
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Don Haller Corvette Club of America 94Coupe, 383Stroka, PeteK Trans, 3000stall, 3.54rear, Konis and bigger sways. |
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BrianCunningham | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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Here's a video explanation
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Posted on: 2010/7/13 15:50
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BrianCunningham | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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in words
Quote:
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Posted on: 2010/7/13 15:52
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Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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CentralCoaster | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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The earth is spherical?
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Posted on: 2010/7/13 20:41
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CentralCoaster | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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The rest makes sense except that I'm stuck on the first part:
"a traditional modern sailing rig can propel a sailing craft to a speed such that it's downwind VMG is greater than the speed of the wind." What is VMG, and how does a sail travel downwind faster than the wind? I understand how it travels faster than the wind, but not in the same direction. |
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Posted on: 2010/7/13 20:43
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BrianCunningham | Re: Can you go downwind faster than the wind? | ||
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Posted on: 2010/7/13 21:16
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BrianCunningham | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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Video
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Posted on: 2010/7/13 21:17
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_________________
Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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CentralCoaster | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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Well that's impressive, never seen that before.
So the blade angle, while rotating still sees a tailwind, even though the vehicle overall is moving faster than the wind. The rest is just energy. The amount of energy going into the sail becomes motion, there's nothing perpetual about it because energy is more than just velocity. Definitely counterintuitive... but really it's kinda like a bicycle in that sense, you can make a wheel rotate faster than your pedals. So the next question is, how much faster can a sailboat go than the wind in theory? |
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Posted on: 2010/7/14 0:09
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BrianCunningham | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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I'd have to look the record up
But iceboats have sailed well over twice the speed of the wind, over 100years ago. |
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Posted on: 2010/7/14 1:21
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Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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CentralCoaster | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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Ok, looks like there is no theoretical maximum which makes sense. I found some articles on iceboats travelling at 4-5x windspeed downwind. Ok, well they don't travel directly downwind, but very cool nonetheless.
Never heard of iceboats before, but it makes sense that they'd be more capable than a sailboat. Ahh, the power of vectors. |
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Posted on: 2010/7/14 1:48
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BrianCunningham | Re: Can you go downwind faster than the wind? | ||
Senior Guru
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and very little resistance!
They were going over 60mph before cars were around. |
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Posted on: 2010/7/14 1:55
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Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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