This article has factual inaccuracies in it.<p>It says: "Blackbird is unique because it can move directly downwind faster than the wind itself for a sustained period. Any sailor worth their salt can tell you that a boat can do that by cutting zigzag patterns; that's called tacking. But the idea that a vehicle can beat the breeze traveling straight downwind, no tacking involved, is controversial."<p>Sailboats travel _upwind_ by tacking, not downwind and measured by forward progress it's significantly slower than the wind speed because the extra distance travelled.<p>Sailboats can travel directly downwind however because hull speed is a thing, only crazy racing boats with hydrofoils so much as approach a significant fraction of wind speed.
I thought this was already solved in Usenet around 1985?<p>"If there is two mediums moving at different speeds, we can harness this energy gradient to do stuff, like moving some objects at some speed. And those three speeds have nothing to do with each other, the generated speed can very well be greater than first two, if the energy harvested is greater than energy needed."