Re: [Vo]:Downwind Faster than the Wind (DWFTTW)
This must be a scam. As Jed said, at the point where the craft is going downwind at the speed of the wind, the relative wind across the propeller would be zero so it could not accelerate from this point on. If it did, the force from the prop would reverse anyway. Even more obviously, if it can accelerate from a position of zero relative wind then one could start it off in no wind conditions and it would accelerate - perpetual motion just isn't that easy! Nick Palmer On the side of the Planet - and the people - because they're worth it Blogspot - Sustainability and stuff according to Nick Palmer http://nickpalmer.blogspot.com
Re: [Vo]:Downwind Faster than the Wind (DWFTTW)
On Wed, 22 Sep 2010 16:01:42 +0100, you wrote: This must be a scam. As Jed said, at the point where the craft is going downwind at the speed of the wind, the relative wind across the propeller would be zero so it could not accelerate from this point on. If it did, the force from the prop would reverse anyway. Even more obviously, if it can accelerate from a position of zero relative wind then one could start it off in no wind conditions and it would accelerate - perpetual motion just isn't that easy! --- I've attached a drawing which shows basically how Thin Air Design's Blackbird vehicle works. Note that with the wind pushing the cart and the pitch of the propeller as shown, the wind would, intuitively, be forcing the propeller to rotate counter-clockwise as viewed from the rear of the cart. However, such is not the case. What's really happening is that the wind is pushing on the prop, forcing the cart to move forward, and the torque generated by the wheels is coupled to the prop in such a way as to cause the prop to rotate clockwise when viewed from the rear. This direction of rotation makes the prop a pusher, and will increase the apparent force of the wind. As long as the wind is blowing from the rear, the cart will accelerate until it reaches wind speed, when the wind speed will effectively be zero. However, because of the prop's action as a pusher, the cart will be going a little faster than wind speed, at wind speed. Then, as soon as the prop feels the headwind it'll stop being a propeller and will become a turbine, driving the wheels and accelerating into the headwind until, eventually, everything settles out and the cart reaches its speed limit. --- --- JF
Re: [Vo]:Downwind Faster than the Wind (DWFTTW)
From John Fields, ... Note that with the wind pushing the cart and the pitch of the propeller as shown, the wind would, intuitively, be forcing the propeller to rotate counter-clockwise as viewed from the rear of the cart. However, such is not the case. What's really happening is that the wind is pushing on the prop, forcing the cart to move forward, and the torque generated by the wheels is coupled to the prop in such a way as to cause the prop to rotate clockwise when viewed from the rear. This direction of rotation makes the prop a pusher, and will increase the apparent force of the wind. As long as the wind is blowing from the rear, the cart will accelerate until it reaches wind speed, when the wind speed will effectively be zero. However, because of the prop's action as a pusher, the cart will be going a little faster than wind speed, at wind speed. Then, as soon as the prop feels the headwind it'll stop being a propeller and will become a turbine, driving the wheels and accelerating into the headwind until, eventually, everything settles out and the cart reaches its speed limit. Well, I'll be keelhauled! Thanks for the clarification John. My previous suggestion of using a control vehicle fitted with a Viking-like sale is woefully inappropriate. It would be more accurate to describe this vehicle's prop as TACKING through the wind. As most sailors know, a sailboat tends to sail the fastest when sailing at an angle of around 45 degrees INTO THE WIND. (I think maximum dynamics is approx 45 degrees into the wind. Feel free to correct me on that point, maitees.) The point being: Sailing closer into the wind seems counter intuitive but it's the truth - insofar as sailboats are concerned. I can see it now. Sailors take note! This opens up a whole new dimension to regatta races. You heard it here first! Where's my parrot. Regards Steven Vincent Johnson www.OrionWorks.com www.zazzle.com/orionworks
Re: [Vo]:Downwind Faster than the Wind (DWFTTW)
Sailboats vary enormously in terms of their favored point of sailing. I would guess that most sailboats do best with the wind on their beam (90 deg.) My boat is best on that point, and I can also sail into the wind to about 28 degrees without pinching, which is exceptionally. Downwind is slow for me, so I often tack downwind, keeping main and gennie filled. I wonder what race committees will say when a sailor shows up with this rig. Thinking of John's explanation, though, I suppose it will not work as there won't be any torque transmission from the wheels to the prop. Right, John? Cheers, Lawry On Sep 22, 2010, at 1:02 PM, OrionWorks - Steven V Johnson wrote: From John Fields, ... Note that with the wind pushing the cart and the pitch of the propeller as shown, the wind would, intuitively, be forcing the propeller to rotate counter-clockwise as viewed from the rear of the cart. However, such is not the case. What's really happening is that the wind is pushing on the prop, forcing the cart to move forward, and the torque generated by the wheels is coupled to the prop in such a way as to cause the prop to rotate clockwise when viewed from the rear. This direction of rotation makes the prop a pusher, and will increase the apparent force of the wind. As long as the wind is blowing from the rear, the cart will accelerate until it reaches wind speed, when the wind speed will effectively be zero. However, because of the prop's action as a pusher, the cart will be going a little faster than wind speed, at wind speed. Then, as soon as the prop feels the headwind it'll stop being a propeller and will become a turbine, driving the wheels and accelerating into the headwind until, eventually, everything settles out and the cart reaches its speed limit. Well, I'll be keelhauled! Thanks for the clarification John. My previous suggestion of using a control vehicle fitted with a Viking-like sale is woefully inappropriate. It would be more accurate to describe this vehicle's prop as TACKING through the wind. As most sailors know, a sailboat tends to sail the fastest when sailing at an angle of around 45 degrees INTO THE WIND. (I think maximum dynamics is approx 45 degrees into the wind. Feel free to correct me on that point, maitees.) The point being: Sailing closer into the wind seems counter intuitive but it's the truth - insofar as sailboats are concerned. I can see it now. Sailors take note! This opens up a whole new dimension to regatta races. You heard it here first! Where's my parrot. Regards Steven Vincent Johnson www.OrionWorks.com www.zazzle.com/orionworks
Re: [Vo]:Downwind Faster than the Wind (DWFTTW)
From Lawry, ... I wonder what race committees will say when a sailor shows up with this rig. Thinking of John's explanation, though, I suppose it will not work as there won't be any torque transmission from the wheels to the prop. Paddle wheels! My parrot can squawk out Steamboat Willy better than yours! Regards Steven Vincent Johnson www.OrionWorks.com www.zazzle.com/orionworks
Re: [Vo]:Downwind Faster than the Wind (DWFTTW)
Here is a pretty good description of how it works: http://scienceblogs.com/goodmath/2008/12/the_real_bozo_attempts_to_aton.php Ron --On Wednesday, September 22, 2010 1:12 PM -0400 Lawrence de Bivort debiv...@evolutionaryservices.org wrote: Sailboats vary enormously in terms of their favored point of sailing. I would guess that most sailboats do best with the wind on their beam (90 deg.) My boat is best on that point, and I can also sail into the wind to about 28 degrees without pinching, which is exceptionally. Downwind is slow for me, so I often tack downwind, keeping main and gennie filled. I wonder what race committees will say when a sailor shows up with this rig. Thinking of John's explanation, though, I suppose it will not work as there won't be any torque transmission from the wheels to the prop. Right, John? Cheers, Lawry On Sep 22, 2010, at 1:02 PM, OrionWorks - Steven V Johnson wrote: From John Fields, ... Note that with the wind pushing the cart and the pitch of the propeller as shown, the wind would, intuitively, be forcing the propeller to rotate counter-clockwise as viewed from the rear of the cart. However, such is not the case. What's really happening is that the wind is pushing on the prop, forcing the cart to move forward, and the torque generated by the wheels is coupled to the prop in such a way as to cause the prop to rotate clockwise when viewed from the rear. This direction of rotation makes the prop a pusher, and will increase the apparent force of the wind. As long as the wind is blowing from the rear, the cart will accelerate until it reaches wind speed, when the wind speed will effectively be zero. However, because of the prop's action as a pusher, the cart will be going a little faster than wind speed, at wind speed. Then, as soon as the prop feels the headwind it'll stop being a propeller and will become a turbine, driving the wheels and accelerating into the headwind until, eventually, everything settles out and the cart reaches its speed limit. Well, I'll be keelhauled! Thanks for the clarification John. My previous suggestion of using a control vehicle fitted with a Viking-like sale is woefully inappropriate. It would be more accurate to describe this vehicle's prop as TACKING through the wind. As most sailors know, a sailboat tends to sail the fastest when sailing at an angle of around 45 degrees INTO THE WIND. (I think maximum dynamics is approx 45 degrees into the wind. Feel free to correct me on that point, maitees.) The point being: Sailing closer into the wind seems counter intuitive but it's the truth - insofar as sailboats are concerned. I can see it now. Sailors take note! This opens up a whole new dimension to regatta races. You heard it here first! Where's my parrot. Regards Steven Vincent Johnson www.OrionWorks.com www.zazzle.com/orionworks
Re: [Vo]:Downwind Faster than the Wind (DWFTTW)
On Wed, 22 Sep 2010 13:12:27 -0400, you wrote: Sailboats vary enormously in terms of their favored point of sailing. I would guess that most sailboats do best with the wind on their beam (90 deg.) My boat is best on that point, and I can also sail into the wind to about 28 degrees without pinching, which is exceptionally. Downwind is slow for me, so I often tack downwind, keeping main and gennie filled. I wonder what race committees will say when a sailor shows up with this rig. Thinking of John's explanation, though, I suppose it will not work as there won't be any torque transmission from the wheels to the prop. Right, John? --- I think so since, even if the prop was coupled to an underwater screw, the coeffiction of friction between the water and the screw would be so much weaker than that between a wheel and the ground that it would be hard to keep the prop from turning the wrong way initially. --- JF
Re: [Vo]:Downwind Faster than the Wind (DWFTTW)
Interesting effects from filming propellers: http://www.youtube.com/watch?v=Y9Px9EAhyssfeature=related http://www.youtube.com/watch?v=Y9Px9EAhyssfeature=related http://www.youtube.com/watch?v=T055cp-JFUA http://www.youtube.com/watch?v=T055cp-JFUA http://www.youtube.com/watch?v=LVwmtwZLG88feature=related http://www.youtube.com/watch?v=LVwmtwZLG88feature=related On Thu, Sep 23, 2010 at 6:23 AM, John Fields jfie...@austininstruments.comwrote: On Wed, 22 Sep 2010 13:12:27 -0400, you wrote: Sailboats vary enormously in terms of their favored point of sailing. I would guess that most sailboats do best with the wind on their beam (90 deg.) My boat is best on that point, and I can also sail into the wind to about 28 degrees without pinching, which is exceptionally. Downwind is slow for me, so I often tack downwind, keeping main and gennie filled. I wonder what race committees will say when a sailor shows up with this rig. Thinking of John's explanation, though, I suppose it will not work as there won't be any torque transmission from the wheels to the prop. Right, John? --- I think so since, even if the prop was coupled to an underwater screw, the coeffiction of friction between the water and the screw would be so much weaker than that between a wheel and the ground that it would be hard to keep the prop from turning the wrong way initially. --- JF
[Vo]:Downwind Faster than the Wind (DWFTTW)
internets provides: http://vimeo.com/10476453 We built a wind powered vehicle designed to go *directly* downwind - faster than the wind. This is the first run of our first outing. We intended these first attempts only as shakeout runs. But we ended up doing better than our ultimate goal of twice windspeed. As a result, we've now set our goal at 3X windspeed. This is the first run of the two days we spent on the lakebed in Ivanpah, NV. We've blanked out the audion in places since it wouldn't be responsible to publish numbers that aren't official. We plan to make a well instrumented official run before the officials of the North American Land Sailing Association soon. Once that data has been certified we will publish all data. http://www.youtube.com/watch?v=xHsXcHoJu-A Downwind Faster than the Wind (DWFTTW)
[Vo]:Downwind Faster than the Wind (DWFTTW) (continued)
also: http://www.fasterthanthewind.org/ internets provides: http://vimeo.com/10476453 We built a wind powered vehicle designed to go *directly* downwind - faster than the wind. This is the first run of our first outing. We intended these first attempts only as shakeout runs. But we ended up doing better than our ultimate goal of twice windspeed. As a result, we've now set our goal at 3X windspeed. This is the first run of the two days we spent on the lakebed in Ivanpah, NV. We've blanked out the audion in places since it wouldn't be responsible to publish numbers that aren't official. We plan to make a well instrumented official run before the officials of the North American Land Sailing Association soon. Once that data has been certified we will publish all data. http://www.youtube.com/watch?v=xHsXcHoJu-A Downwind Faster than the Wind (DWFTTW)
Re: [Vo]:Downwind Faster than the Wind (DWFTTW)
I do not see how this can work! They are going with the wind, so if they start to travel at the same speed as the wind, the propeller should stop turning. Maybe I am missing something. - Jed
Re: [Vo]:Downwind Faster than the Wind (DWFTTW)
well, their own speed would let the prop spin as drag, but it would have to slow down eventually. On Tue, Sep 21, 2010 at 10:26 AM, Jed Rothwell jedrothw...@gmail.com wrote: I do not see how this can work! They are going with the wind, so if they start to travel at the same speed as the wind, the propeller should stop turning. Maybe I am missing something. - Jed
RE: [Vo]:Downwind Faster than the Wind (DWFTTW)
Wouldn't you know - they even have a url http://www.fasterthanthewind.org/ -Original Message- From: Jed Rothwell I do not see how this can work! They are going with the wind, so if they start to travel at the same speed as the wind, the propeller should stop turning. Maybe I am missing something. - Jed
Re: [Vo]:Downwind Faster than the Wind (DWFTTW)
I am guessing that the propeller propels a belt/chain which is geared into the wheels. Lawry On Sep 21, 2010, at 1:26 PM, Jed Rothwell wrote: I do not see how this can work! They are going with the wind, so if they start to travel at the same speed as the wind, the propeller should stop turning. Maybe I am missing something. - Jed
Re: [Vo]:Downwind Faster than the Wind (DWFTTW)
On Tue, 21 Sep 2010 13:26:47 -0400, you wrote: I do not see how this can work! They are going with the wind, so if they start to travel at the same speed as the wind, the propeller should stop turning. Maybe I am missing something. - Jed --- Notice from the pitch of the propeller and its rotation that it's turning in the wrong direction if it's being driven like a turbine. As I understand it, what's happening is that the drag from the prop (and everything else at the rear of the vehicle) is being used to push the vehicle forward and turn the wheels, and the wheels are geared to the prop in a way to make it turn backwards. So, while the wheels are causing the prop to spin until the vehicle achieves wind speed, after that it'll be heading into the wind, the prop will start acting like a turbine, and the torque developed will be used to turn the wheels and make the vehicle run upwind, --- JF
Re: [Vo]:Downwind Faster than the Wind (DWFTTW)
On 9/22/2010 1:26 AM, Jed Rothwell wrote: I do not see how this can work! They are going with the wind, so if they start to travel at the same speed as the wind, the propeller should stop turning. Maybe I am missing something. Yes what an interesting puzzle! But knowing that it can be done and armed with the clues that the device has wheels and a propeller - it doesn't take very long to figure out how it could be done. Consider the fact that it takes almost no energy to travel at the same speed with the wind, and also consider that since you have access to both the air (via the propeller) and the ground (via the wheels), and since these things are in motion with respect to each other (the wind), it must be possible to extract energy from that differential motion and use it to drive the device faster than the wind. The only question is how! Now suppose the wheels have a circumference of say 1 meter and suppose we set the pitch of the propeller so that it also has a screw pitch of 1 meter per revolution and then suppose we connect these two things together with a 1:1 drive shaft arrangement. Now we have the situation that no matter what speed the device moves at *in still air*, the propeller slices perfectly edgewise through the air and produces no thrust or drag force via the propeller or wheels. Now supposing we cut the shaft and interpose an electrical generator in the shaft so that its stator is linked to the wheels and its rotor is linked to the propeller. Now we have built a windmill generator that works identically regardless of its motion along the ground! If there is no wind then no matter what speed it rolls at with respect to the air, no power is produced or consumed by the generator. But supposing there is some wind - then again no matter what speed it rolls at with respect to the wind - the wind produces the same differential motion between the stator and armature and thus exactly the same power whether it is moving or stationary! So this is the type of device we are looking for. It can roll along at the same speed as the wind - consuming almost negligible energy in air friction (because it is not moving relative to the air) and only a minute amount of energy in wheel and shaft bearing friction (thanks to modern bearings etc) - and all the time it can be generating exactly the same power as if it was locked to the ground with the wind driving the generator via the propeller in the normal manner. Clearly this power is available to be used to drive the device faster than the minimal friction situation of rolling at the same speed as the wind. The only remaining question is the actual detail of how this available power can be most efficiently applied to the wheels. My guess is that you don't bother with a generator but simply have a variable ratio gear box between the propeller and wheels. Or simplest of all have a variable pitch propeller!
Re: [Vo]:Downwind Faster than the Wind (DWFTTW)
Quite baffling. I love the amount of conjecture this tiny little transportation device has spontaneously generated within the Vort Collective. Nice to see that the Vort juices haven't completely atrophied. Creative conjecture of this sort seems to have been kind of sparse lately! ;-) I still remain skeptical of the claims, but would enjoy being proven wrong. This device reminds me of a gyro-copter, albeit a grounded gyro-copter. I wonder if similar laws of physics are involved. At present there are inadequate controls, IMHO. I wish they had a similar device outfitted with traditional sales akin to a Viking ship running alongside the one with the ingenious prop design. Would be nice to make speed comparisons as they throw spears at each other. Yeah, that's it... A lack of adequate controls. That's what's bugging me. More controls please! Regards, Steven Vincent Johnson www.OrionWorks.com www.zazzle.com/orionworks
Re: [Vo]:Downwind Faster than the Wind (DWFTTW)
I think we can think of this in terms of three phases: 1. Start from a dead stop 2. Acceleration to a speed superior to that of the wind 3. Post acceleration performance 1. I am guessing that the contraption just starts moving forward because of the push of the wind on its vertical surface, e.g. prop, structure, passenger cockpit, etc. No wind = no movement Note how slowly the thing starts to move. 2. As the wind increases the speed of the prop, it transmits more power via a belt/chain to the wheels, probably via a fixed gearing, but it could be variable The wind keeps pushing the thing until its speed equals that of the wind. When the speed exceeds that of the wind, the thing faces a drag. I am going to guess that the thing moves faster than the speed of the wind for a (short) while due to the mass/kinetics/momentum of the prop, which continue after reaching wind speed/vehicle speed equilibrium and so impart some energy to the wheels to exceed wind speed. 3. But how long can this excess speed be maintained? The clip shows the vehicle slowing pretty quickly after it exceeds the wind speed. This is attributed to the brakes in the clip, but perhaps it is no more than drop in the mass/kinetics/momentum of the prop that occurs when the wind is no longer maintaining its speed-increasing motion. Assuming the thing works as advertised, I suppose the vehicle could move downwind with an oscillating speed, dropping to the point where the prop begins to supply positive drive, and then re-accelerating to the point where wind speed is no longer sufficient to do so. Of course, we are making one critical assumption: that the vehicle is actually moving straight down-wind, rather than at an angle to it. (Think of a gyrocopter, mounted vertically, with the wind providing the forward thrust.) Interestingand impressive to a sailor like me who has often cursed down-wind speeds. Lawry On Sep 21, 2010, at 2:41 PM, Lawrence de Bivort wrote: I am guessing that the propeller propels a belt/chain which is geared into the wheels. Lawry On Sep 21, 2010, at 1:26 PM, Jed Rothwell wrote: I do not see how this can work! They are going with the wind, so if they start to travel at the same speed as the wind, the propeller should stop turning. Maybe I am missing something. - Jed
RE: [Vo]:Downwind Faster than the Wind (DWFTTW)
Ah yes, it is the old mystery of capturing apparent wind. Apparent wind is the wind that you make yourself i.e. you feel on your face as you move forward such as on a bicycle. True wind is the wind that is blowing naturally. There is a long-forgotten way it could be done today, with huge OU implications, you know: capturing the very wind you make yourself g ... for those who do not appreciate a little humor, stop here. http://blog.modernmechanix.com/2007/04/07/propeller-drives-novel-bicycle/ Hey, had this guy not caved into the expert scientists of the day, those that said he could not capture some of his own apparent wind, we might all be riding wind-cycles today :) Maybe the Russians are using the technique on the this helicopter, which seems to be getting a massive amount of lift with almost no blade speed ... cough, cough. http://www.youtube.com/watch?v=qgvuQGY946g Seriously vorticians, if you pedal into the wind on a bicycle, your leg torque overcomes both kinds of wind drag. The proper comparison is between torque and drag. Same with the torque from the wheels of a land sailor. Never mind that some of the torque comes from the wind you make yourself even though, above the speed of true wind there is additional drag. At least between 1x and 3x true wind, it appears there is no net drag (vs torque extracted) in a good design. Jones
Re: [Vo]:Downwind Faster than the Wind (DWFTTW)
On Tue, Sep 21, 2010 at 3:51 PM, Jones Beene jone...@pacbell.net wrote: Maybe the Russians are using the technique on the this helicopter, which seems to be getting a massive amount of lift with almost no blade speed ... cough, cough. http://www.youtube.com/watch?v=qgvuQGY946g Personally, I liked the twin rotor vid that popped up on the suggestions column: http://www.youtube.com/watch?v=WQKyxw8Sa9MNR=1 T
