lemur Posted February 16, 2011 Share Posted February 16, 2011 Someone seems to have redeveloped an older concept and won an award for it:http://www.greenoptimistic.com/2011/02/09/dickson-ekranoyacht/ The fact that this vehicle's efficiency is being attributed to its use of hydrogen as fuel leads me to question its validity, since hydrogen is not a fuel but a storage medium. Still, I'm wondering about the claims that such a low-flying boat/plane could actually be more efficient than a non-flying boat. Surely it is much less efficient than a passenger Jet flying at very high-altitude, but how much less? Link to comment Share on other sites More sharing options...
Mr Skeptic Posted February 16, 2011 Share Posted February 16, 2011 Hydrogen is a fuel. It is also like the article said, an energy carrier. It's not an energy source but that is not what the article said. Link to comment Share on other sites More sharing options...
SMF Posted February 16, 2011 Share Posted February 16, 2011 (edited) The Green Optimistic website also has a flagged tip for Recommended Reading: How to run your car on water. This involves the production of high energy HHO gas for injection into the intake of an internal combustion engine. I don't trust websites that promote hoaxes. SM Edited February 16, 2011 by SMF 1 Link to comment Share on other sites More sharing options...
TonyMcC Posted February 16, 2011 Share Posted February 16, 2011 A large factor in the efficiency of this machine is known as "Ground Effect". The actual fuel used is (imo) not really that important as far as efficiency is concerned although using hydrogen will result in less polution. 1 Link to comment Share on other sites More sharing options...
CaptainPanic Posted February 17, 2011 Share Posted February 17, 2011 The part that I really don't understand is that they use fuel cells. Fuel cells can turn hydrogen (with oxygen) into water and electricity. Why would they want to have electricity? Are they using propellors to move air? What's wrong with turbines? If it is true that they have fuel cells, and electric engines, this seems like a very heavy solution, and if you want to hover above the water, then weight is a much bigger issue than with ordinary ships. Link to comment Share on other sites More sharing options...
TonyMcC Posted February 17, 2011 Share Posted February 17, 2011 I don't know much about fuel cells but if you google - hydrogen fuel cell aircraft - there does seem to be quite a bit of research along those lines. Link to comment Share on other sites More sharing options...
lemur Posted February 17, 2011 Author Share Posted February 17, 2011 Good points about hydrogen, but what about the question of comparative efficiency of flying just above the waves vs. sailing through them vs. flying at high altitude? Surely high-altitude flying is more efficient . . . except for the amount of energy needed to reach cruising altitude. Then I would think that air-resistance would be less energy-expensive than water-drag, so maybe this is really a more efficient form of transit than either high-altitude flight OR boating through water. Link to comment Share on other sites More sharing options...
Mr Skeptic Posted February 17, 2011 Share Posted February 17, 2011 Yeah, it seems to me that this is like making a crippled airplane. If they want to go so close to the water why not just use one of these: http://en.wikipedia.org/wiki/Hydrofoil It "flies" on water greatly reducing friction, but can still carry huge loads (including itself so it doesn't have to be made from light, expensive, and very un-green materials). And it can use water to propel itself which is 1000 times denser than air. Link to comment Share on other sites More sharing options...
TonyMcC Posted February 17, 2011 Share Posted February 17, 2011 (edited) Its all to do with angle of attack. This is the angle the wing makes to the direction of movement through air. This movement causes an increase of pressure under the wing and,to a greater extent, a decrease in pressure above the wing. These cause the wing to be forced upwards (known as lift). Up to a point ( where the wing will stall) in general the greater the angle of attack the greater the lift. However as the angle of attack is increased the force needed to push the wing through the air also increases quite dramatically. This resistance to movement is called drag. When flying very close to the surface the aircraft will experience extra pressure under the wing . This increase of pressure reduces the necessary angle of attack needed to keep the craft flying. This reduction of angle of attack reduces drag - hence greater efficiency. There are other factors that improve efficiency when near the ground such as destruction of air vortices that form at the wig tips and which cause extra drag. The hydrofoil "wings" fly through water which is much thicker than air and so offers more resistance to movement! Also I doubt whether hydrofoils will be able to match the speed of proposed craft utilising ground effect. Edited February 18, 2011 by TonyMcC Link to comment Share on other sites More sharing options...
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