Even if you are sailing directly downwind, it works. That was actually the professor’s demonstration. He said that at the time it was accepted as a physical phenomenon, there were many physicists who said it wasn’t possible, but it was being actively used by some engineers to make jets go in reverse.
If you were to put a big fan on a sailboat and point it at the sail, it would move the sailboat in a similar way as if the wind was pushing the sail.
Which actually makes sense if you understand it’s not the wind pushing but the generated updraft at the sail.
(also not point at, but sideways)
😁
Even if you are sailing directly downwind, it works. That was actually the professor’s demonstration. He said that at the time it was accepted as a physical phenomenon, there were many physicists who said it wasn’t possible, but it was being actively used by some engineers to make jets go in reverse.
Cool stuff!
(I am not in aerospace or sailing, so I was guesstimating)