Alan Whitmore
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Last April I was visiting a Special Projects lab at the NASA facility in Huntsville, where research was being done on a solar sail, which would use the "photon wind" from the sun to power a spacecraft. I asked whether such a craft was limited to moving away from the sun, or whether it might tack "upwind", back towards the sun. I got no answer that satisfied me, I got the impression that such a question had never occurred to them.
My own opinion, totally without evidence to back it up, was that without a keel, tacking would not be possible. A sailboat moves simultaneously in two fluids with very different viscosities, and that with a keel digging into the more viscous fluid (water) and providing some leverage, the boat would be limited to sailing away from the wind, like dust motes floating through the air.
Anybody else have any opinions on this, especially those of you who are experienced sailors?
My own opinion, totally without evidence to back it up, was that without a keel, tacking would not be possible. A sailboat moves simultaneously in two fluids with very different viscosities, and that with a keel digging into the more viscous fluid (water) and providing some leverage, the boat would be limited to sailing away from the wind, like dust motes floating through the air.
Anybody else have any opinions on this, especially those of you who are experienced sailors?