Who said there's "extra energy"?xerxes wrote:Where does the extra energy come from?
But can you make a downwind tack in which your downwind component is faster than the wind? If so, that would be a good start.boarini2003 wrote:I know you can sail faster than the wind speed, but not directly downwind.
Sorry Rick, you're not going "directly" downwind. You're losing altitude. Or if you're flying in lift there's a vertical wind component you're not matching.Rick M wrote:When I am on downwind in my hang glider I'm going faster than the wind. Of course gravity is adding the extra energy. So yes, you can do this. It just requires the use of altitude and gravity.
Perhaps I'll make it harder for you sg, and require that it be done with typical sails moving in a typical manner.sg wrote: The problem is, its an airfoil that stops generating lift when you approach downwind. So change the type of airfoil you are using Hint hint...
sg wrote: Now think about the sail. Its a lift generating airfoil right? The problem is, its an airfoil that stops generating lift when you approach downwind. So change the type of airfoil you are using Hint hint...
Of course that brings up another interesting HG question:Rick M wrote:When I am on downwind in my hang glider I'm going faster than the wind. Of course gravity is adding the extra energy. So yes, you can do this. It just requires the use of altitude and gravity.
D'OH!!! You jumped the gun. That's not a hoax. That is one of several methods that can be done (the most practical one in fact). There are several more approaches as well.JDyer wrote:Check this out. I believe it is impossible and that this is a hoax but believe what ever you want....
Hmmm.... Dynamic soarding requires a wind gradient. Good catch. I suspect you can beat the average wind vector directly downwind this way. You wouldn't be going directly downwind, but tacking in a sense. But with the right amount of trickery, that can probably be taken care of.Not sure if this is what you're thinking about, and you've got to be totally nuts to try it but:
I wish it were so. Then I'd be filthy rich. It can in fact be done, and doesn't require perpetual motion. The secret is that we're extracting the real energy that arises from the difference in speed between the wind and water (or wind and ground, or wind and wind). That's why we need a "special" vehicle. A typical sailing vessel primarily extracts the energy arising out of the difference in speed between the wind and the vehicle (this is only strictly true when running directly downwind).JDyer wrote:if you can go dwfttw with no other energy you just invented perpetual motion
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