[geoschmo]

This is a facinating thread. Very deep for a game forum. Basically everybody has had a little piece of the truth.

A ship with a square sail and no keel or rudder (a raft) will go in the direction of the prevailing wind. If you turn the sail to try and move at an angle with the wind, the wind will simply rotate your ship so that the square sail is once again perperdicular to it.

A ship with a square sail and a keel or rudder can follow the wind or go at angles to the wind (but still with it) because the friction of the water against the keel or rudder will keep the ship from rotating.

A ship with a triangular sail can go into the wind at angles by aerodynamic principles similer to how a wing on an aircraft generates lift.

A solar sail can go with the "solar wind" or at angles to it by newtons principles of equal and opposite reaction. If you turn your sail at an anlge to the solar wind it will push your ship at an angle to the wind. It will also try to rotate your sail back to perpendicular, but by use of chemical rockets or some other thrust generating device you can keep the sail at the anlge you want. Similar to the keel or rudder on a water craft.

No principle I can think of would allow a solar sail to go into the solar wind. An interstellar solar sailing ship would use the force of a star to get enough velocity. Once up to velocity, it would use the destination star's wind to brake. If you wanted to travel through a system without stopping you would have to retract the sail while approaching the star. Once past it you could extend the sail again to use that star to continue you on your journey or change course.

[This message has been edited by geoschmo (edited 11 January 2001).]