 |
| Blackbird Sailing Craft |
Let's say the wind is blowing to the north at 10 mph. Let's say you have a balloon and sailboat at the same wharf: At same time that the balloon is released into the wind, the boat departs on a northerly heading (heading north, for you landlubbers). After about an hour with the wind at their backs, which of the two will be further ahead of the other?
Assuming there are no troublesome circumstances -- like the balloon's losing height, or heavy seas' capsizing the boat -- the answer is that they should both be about 10 miles north of the wharf after one hour. Actually, the boat probably would be a bit behind, because it had to move against the resistance of the water along its hull. So the balloon wins! And without a boatswain or coxswain or any swain at all. Did you know that "boatswain" is pronounced "bos'un"?
How can a balloon be faster than a sailboat? No matter how much following wind is captured by an object (such as a sail), the boat can only go as fast as the wind that is "pushing" it along. Unless it has oarsmen aboard, the boat has no additional external energy source to push it faster than the following wind. In the example above, once the boat reaches 10 mph, it will begin to meet wind resistance from the air front of it, and that means trouble for a sailboat. The balloon runs into the same barrier, but without the added resistance of the waves underneath.
Sailors are already shouting at this blog: "What about tacking!?" My response to those sailors is: "Don't you mean jibing?!" If the sailors are British, I would shout, "Don't you mean gybing?!" Before you know it, we are throwing limes at each other. Sailors have devised a way to defeat common sense by being able to sail INTO a headwind. They do this by tacking, which is a method of zig-zagging the bow (front) of the boat at about a 45-degree angle toward the headwind. I won't go into details here about how that works, because I would be getting off topic. Just believe me that this is a well-proven method of sailing that dates back even further than Gilligan and the S.S. Minnow.
Jibing, on the other hand, is using the same method of zig-zagging the bow, but with a following wind instead of a headwind. In fact, a boat that is jibing can actually travel FASTER than the wind is blowing. So, now both you and the sailors are yelling at me that a boat that jibes would defeat the cunning opponent balloon. And I would respond that such thinking does not jive with geometry. It is true that the boat would be traveling faster than the balloon, but because it is zig-zagging left and right at 45-degree angles, it is actually traveling much further than the straight path of the balloon -- so what is gained by speed is lost by distance.
I could probably end the blog entry right here, and you would grateful for having learned about sailboats and balloons. But my purpose is not to explain sailing terminology. The raison d'être of this entry is to tell you of an amazing invention that travels downwind in a straight course (no jibing), and using only the wind at its back as an energy source, moves faster than twice the speed of the wind! This, of course, runs counter to all intuition, and the sailors have resumed throwing limes at me.
Ice-boats and land-yachts -- land vehicles with sails that slide across icebeds or flatlands on skids or wheels -- can actually win a race against a balloon by jibing, because they have much less resistance than a boat does on water. However, if they raced in straight line downwind, even they cannot defeat the now arrogant balloon, because even they are limited to the speed of the wind.
So, this guy Rick Cavallaro had an idea, based on earlier ideas, speculation, and experiments: Instead of zig-zagging the bow of a land-yacht back and forth at 45-degree angles, what if you kept the bow straight and just rotated the sail? Well, that wouldn't work, because the vehicle would turn sharply to the right or left. If you somehow forced the bow to remain straight, then you wouldn't even be catching all of the following wind, because your sail would be at an angle. Ok, then what if you put the angled sail on a very tall mast, and allowed it to rotate in a circle? And put a second one on, so it captures even more wind? Well, that actually describes a propeller system, doesn't it? Yes, it does. Did you ever notice how sails and propellers look very similar? They are both designed to capture wind in order to push or pull a vehicle forward [see It's a Boat! It's a Plane! No, It's an Ekranoplan! for an explanation of the concepts of flight].
The wind should push the vehicle forward, rotating the propeller/sails. If the energy of the spinning windmill-like propellers were connected to a pulley/gear system that would rotate the wheels of his land-yacht, Cavallaro theorized that the rotation of the wheels would move the vehicle even faster, and eventually it would exceed the speed of the wind itself.
Almost every expert in the world, in addition to common sense, ridiculed the idea, saying that it had the markings of a perpetual-motion machine, and could not work under the present set of the laws of physics. However, for some very odd, inexplicable reason, it did work exactly as he had predicted. To quiet persistent skeptics, Cavallaro had the North American Land Sailing Association (NALSA) certify his runs. In July 2010, under strict NALSA parameters, he was able to attain a rating of about 28 MPH in a 10 MPH wind -- 2.8 times wind speed. Unofficially, he has been able to achieve speeds up to 54 MPH in a 15-MPH wind, about 3.5 times wind speed.
Scientists still are at a loss to explain why this works. An even bigger conundrum is: What process or product can be produced utilizing this amazing discovery and knowledge, besides having fun on flat dried salt lakes?
Assuming there are no troublesome circumstances -- like the balloon's losing height, or heavy seas' capsizing the boat -- the answer is that they should both be about 10 miles north of the wharf after one hour. Actually, the boat probably would be a bit behind, because it had to move against the resistance of the water along its hull. So the balloon wins! And without a boatswain or coxswain or any swain at all. Did you know that "boatswain" is pronounced "bos'un"?
How can a balloon be faster than a sailboat? No matter how much following wind is captured by an object (such as a sail), the boat can only go as fast as the wind that is "pushing" it along. Unless it has oarsmen aboard, the boat has no additional external energy source to push it faster than the following wind. In the example above, once the boat reaches 10 mph, it will begin to meet wind resistance from the air front of it, and that means trouble for a sailboat. The balloon runs into the same barrier, but without the added resistance of the waves underneath.
Sailors are already shouting at this blog: "What about tacking!?" My response to those sailors is: "Don't you mean jibing?!" If the sailors are British, I would shout, "Don't you mean gybing?!" Before you know it, we are throwing limes at each other. Sailors have devised a way to defeat common sense by being able to sail INTO a headwind. They do this by tacking, which is a method of zig-zagging the bow (front) of the boat at about a 45-degree angle toward the headwind. I won't go into details here about how that works, because I would be getting off topic. Just believe me that this is a well-proven method of sailing that dates back even further than Gilligan and the S.S. Minnow.
Jibing, on the other hand, is using the same method of zig-zagging the bow, but with a following wind instead of a headwind. In fact, a boat that is jibing can actually travel FASTER than the wind is blowing. So, now both you and the sailors are yelling at me that a boat that jibes would defeat the cunning opponent balloon. And I would respond that such thinking does not jive with geometry. It is true that the boat would be traveling faster than the balloon, but because it is zig-zagging left and right at 45-degree angles, it is actually traveling much further than the straight path of the balloon -- so what is gained by speed is lost by distance.
I could probably end the blog entry right here, and you would grateful for having learned about sailboats and balloons. But my purpose is not to explain sailing terminology. The raison d'être of this entry is to tell you of an amazing invention that travels downwind in a straight course (no jibing), and using only the wind at its back as an energy source, moves faster than twice the speed of the wind! This, of course, runs counter to all intuition, and the sailors have resumed throwing limes at me.
Ice-boats and land-yachts -- land vehicles with sails that slide across icebeds or flatlands on skids or wheels -- can actually win a race against a balloon by jibing, because they have much less resistance than a boat does on water. However, if they raced in straight line downwind, even they cannot defeat the now arrogant balloon, because even they are limited to the speed of the wind.
So, this guy Rick Cavallaro had an idea, based on earlier ideas, speculation, and experiments: Instead of zig-zagging the bow of a land-yacht back and forth at 45-degree angles, what if you kept the bow straight and just rotated the sail? Well, that wouldn't work, because the vehicle would turn sharply to the right or left. If you somehow forced the bow to remain straight, then you wouldn't even be catching all of the following wind, because your sail would be at an angle. Ok, then what if you put the angled sail on a very tall mast, and allowed it to rotate in a circle? And put a second one on, so it captures even more wind? Well, that actually describes a propeller system, doesn't it? Yes, it does. Did you ever notice how sails and propellers look very similar? They are both designed to capture wind in order to push or pull a vehicle forward [see It's a Boat! It's a Plane! No, It's an Ekranoplan! for an explanation of the concepts of flight].
The wind should push the vehicle forward, rotating the propeller/sails. If the energy of the spinning windmill-like propellers were connected to a pulley/gear system that would rotate the wheels of his land-yacht, Cavallaro theorized that the rotation of the wheels would move the vehicle even faster, and eventually it would exceed the speed of the wind itself.
Almost every expert in the world, in addition to common sense, ridiculed the idea, saying that it had the markings of a perpetual-motion machine, and could not work under the present set of the laws of physics. However, for some very odd, inexplicable reason, it did work exactly as he had predicted. To quiet persistent skeptics, Cavallaro had the North American Land Sailing Association (NALSA) certify his runs. In July 2010, under strict NALSA parameters, he was able to attain a rating of about 28 MPH in a 10 MPH wind -- 2.8 times wind speed. Unofficially, he has been able to achieve speeds up to 54 MPH in a 15-MPH wind, about 3.5 times wind speed.
Scientists still are at a loss to explain why this works. An even bigger conundrum is: What process or product can be produced utilizing this amazing discovery and knowledge, besides having fun on flat dried salt lakes?
Scientists are certainly not at a loss to explain why this works. There is nothing esoteric about it: basic Newtonian mechanics will suffice for the analysis. See for instance http://tinyurl.com/3pttvja
ReplyDeleteObviously, not all scientists are at a loss (as your link shows). However, some very credible ones are. Rhett Allain, a physicist at Southeastern Louisiana University and a blogger for ScienceBlogs, felt that this downwind theory has a “free energy problem" and has concluded that “you can’t get something for nothing.” Also, Daniel Kammen, head of UC Berkeley's Renewable and Appropriate Energy Laboratory, had explained that the theory was impossible “due to conservation of energy.” So, perhaps they should read your link.
ReplyDelete