Depending on how you hoist the sail, one can also.say that the sails capture energy from the flow like a impulse/reaction turbine vane.
Ah, that is true when you are running before the wind and use either a square sail like the Roman ships of old , or the more modern way of sailing by opening out the main sail fully to a side and unfurling a spinnaker. But the question was how do you sail upwind ?
The answer to that is by tacking. So how exactly do you zig-zag upwind ? Basically, the it is like this. You obviously can't sail directly upwind. So point the bow slightly off dead ahead , then given that, you have an apparent wind (i.e., vector add the wind blow straight head towards you and the boat velocity at a certain heading , the resultant will be the apparent wind blowing from somewhere between ahead to the beam). So, now the sail is an airfoil (just imagine a cross section), and you position it in the apparent wind,it will generate a lift and a drag. Resolve those along the length of the boat and perpendicular to it, and you get a force driving the boat forward in the given heading and a force dragging the boat perpendicular to it. Now, sail boats have huge keels precisely for this reason,to counteract that force dragging it perpendicular to that heading. As you are going diagonally upwind, to go straight ahead, you have to zig-zag.
Google around there will be articles with pictures
sankum wrote:Just read the paper below.
If I can summarise that paper in one sentence, it is this.
As the plane leaves the ski jump it is below take off speed!It is thrown up in the air ballistically like a bullet
So, in Inglees the paper says.
The plane is not flying as it leaves the ramp, but it sinks back vertically like anything thrown up and the design point is for it to start flying at the deck level as it sinks!
In Yindee I said
As you are thrown up ballistically, what you get is enough time, so that the engine can get the plane up to flying speed before you hit the water!
So with that, all this "Angle of Attack" business is moot. So yeah, while the plane might have an angle of attack as it leaves a moving ship (with a stationary ship, the angle of attack is zero , just like it is for a plane zooming up vertically) due to the apparent wind, the plane is not flying yet and the predominant thing working here is like a pure ballistic thing, with the engine working during the time to get it up to flying speed as it fall slowly back.