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A sail ship leverages the keel’s resistance to turning moments to allow a wind crossing a sail at an angle to tack, achieving a speed greater than the driving wind. But is it possible at all for an airship to also translate turning moment energy into forward energy? Such that a keel surface and sail surfaces can result in a velocity greater than the driving wind?

I realize we do not have any sail powered airships today. It does seem impossible except in the special case of sailing on a thermal boundary layer.

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    $\begingroup$ You will get much better feedback for your question if you post this to the Engineering stack exchange at engineering.stackexchange.com $\endgroup$ – KF Gauss Sep 24 at 4:01
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No, it cannot. The reaction force necessary for a sailboat to tack is furnished by its keel moving through the water and for a land yacht the wheels rolling on the ground furnish the reaction force. Without something to generate that reaction force, the airship cannot tack.

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    $\begingroup$ basically, sailboats move through two media at once, and can use the difference in the movements of these media. Airships float in only one medium, so they never can exploit that difference. $\endgroup$ – Peter Kämpf Sep 20 at 19:26
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Hot air balloonists often select an altitude where the wind is going in the direction they want to go.

One way an airship could tack is if it could lower a sail, or fly a kite, into a stream of air going a different direction that the air in which the airship is immersed.

Another way an airship could tack more effectively would be for it to lower a keelboard into water. The keelboard could be attached to the airship by ropes.

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