wrote in message
The only extra gain you can have beyond the numbers I provided is by
getting the sail tilted around the closest approach point, to get a
force component along the trajectory. This only yields an advantage
along a short fraction of the trajectory in the case described. The
overall result doesn't chage appreciably. You're welcome to try and
calculate.


my point is that your *proof* was flawed. Your derived bound is not
indeed a bound.

Example: Tether pair of solar sails with accurate independant tilt
control (also rapid), there speeds of rotation can simply continue to
incress untill the teather breaks...

Using the reverse angular momentum manover speeds of up to 50 AU per
year are possable with moddest tech addvance in solar sails. Sure you
need to wait a long time to get to the nearest star. But it *is*
doable. This kind of space exploration will need missions lasting many
10's of years and even lasting gererations.

There is no requierement for nature to allow sci-fi type space travel.
It *may* never be possable. In which case this is a real option.

Greg