This thing is 400 sq.m. and tares 23kg? That's about 66' square and 50 lbs. Doesn't seem very light to me. The article talks about spans of 80-160 m. (6400-25600 sq.m.) "depending on [sic] the mass of the craft" (OB-viously).
Has anybody seen anything anywhere concerning the pressure of raw sunlight at 1 AU? Can't be much. No matter what the velocity boost from a rocket, the acceleration can't amount to a lot.
That was from this site:
http://www.ugcs.caltech.edu/~diedrich/solarsails/intro/intro.html
Not much. At first.
But there's nothing to slow that 'not much' down, so every second you have your 'sail' unfolded, you add that much more.
Second after second after second. Minute after minute. Hour after hour.
I read a dissertation on it, literally decades ago. It's not the initial velocity thrust that works for you in this case, it's the longevity and the consistancy of the thrust, weak though it may be. Literally days, weeks, months of low but constant thrust, constantly compounding.
Still like Project: ORION better, though. It goes 'boom', big time.
= )