Posted by XR650L_Dave on January 5, 2009, 1:58 pm
Anyone else see the whole 'can you build a cart that will go downwind
faster than the wind' schtick that's been floating about?
May be old news to some of you yachting types out there.
Interesting mechanism at work, and it does seem quite possible.
Dave
Posted by JayC on January 5, 2009, 5:18 pm
> Anyone else see the whole 'can you build a cart that will go downwind
> faster than the wind' schtick that's been floating about?
> May be old news to some of you yachting types out there.
> Interesting mechanism at work, and it does seem quite possible.
Depends on whether or not you are going downhill.
I'd like to see a link of a proposed machine. Problem is, from a pure
(non-cheating) approach where the only form of power is the wind, when
you are going downwind faster than the wind, relative to you, the wind
is blowing in your face. Even worse, at the moment you exactly match
the windspeed, relative to you, there is no wind, so the way I figure
it, you have to design a machine that will ACCELARATE with no input
power. That is a worse problem than the infamous perpetual motion
machine, which only has to stay in motion.
JayC
Posted by john on January 5, 2009, 5:50 pm
ice boats go wicked fast...
it's more of a side wind than a down-wind
http://www.southdakotamagazine.com/word/wp-content/iceboat.jpg
btw we're doomed the navy is now using kites to save fuel...
john
>> Anyone else see the whole 'can you build a cart that will go downwind
>> faster than the wind' schtick that's been floating about?
>>
>> May be old news to some of you yachting types out there.
>>
>> Interesting mechanism at work, and it does seem quite possible.
> Depends on whether or not you are going downhill.
> I'd like to see a link of a proposed machine. Problem is, from a pure
> (non-cheating) approach where the only form of power is the wind, when
> you are going downwind faster than the wind, relative to you, the wind
> is blowing in your face. Even worse, at the moment you exactly match
> the windspeed, relative to you, there is no wind, so the way I figure
> it, you have to design a machine that will ACCELARATE with no input
> power. That is a worse problem than the infamous perpetual motion
> machine, which only has to stay in motion.
> JayC
Posted by XR650L_Dave on January 5, 2009, 7:30 pm
> ice boats go wicked fast...
> it's more of a side wind than a down-windhttp://www.southdakotamagazine.com/word/wp-content/iceboat.jpg
> btw we're doomed the navy is now using kites to save fuel...
> john
> >> Anyone else see the whole 'can you build a cart that will go downwind
> >> faster than the wind' schtick that's been floating about?
> >> May be old news to some of you yachting types out there.
> >> Interesting mechanism at work, and it does seem quite possible.
> > Depends on whether or not you are going downhill.
> > I'd like to see a link of a proposed machine. Problem is, from a pure
> > (non-cheating) approach where the only form of power is the wind, when
> > you are going downwind faster than the wind, relative to you, the wind
> > is blowing in your face. Even worse, at the moment you exactly match
> > the windspeed, relative to you, there is no wind, so the way I figure
> > it, you have to design a machine that will ACCELARATE with no input
> > power. That is a worse problem than the infamous perpetual motion
> > machine, which only has to stay in motion.
> > JayC
You have 2 iceboats tacking, one left the other right (away from each
other), then they both tack the other way (towards each other), over
and over, now connect them with a pole that can change length, stick a
seat in the middle of the pole...
Not sure it has anything to do with this, bit it makes for an
interesting image.
Dave
Posted by sturd on January 5, 2009, 6:14 pm
JayC says:
> it, you have to design a machine that will ACCELARATE with no input
> power. That is a worse problem than the infamous perpetual motion
> machine, which only has to stay in motion.
You have to go across the wind for it to work. You're actually
creating
lift in the direction of travel. As you may know, very large forces,
about enough to lift a 747, are available. F is still non-zero as long
as you are in motion relative to the wind, just got to get your
wing (sail) pointed right so F is pointed right.
Get out your fluid dynamics book and reread compressible flow.
Go fast. Take chances.
Mike S.
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> faster than the wind' schtick that's been floating about?
> May be old news to some of you yachting types out there.
> Interesting mechanism at work, and it does seem quite possible.