Zach Hazen <<hazenz>>
writes:

An explanation here:
https://en.wikipedia.org/wiki/Wing_loading#Effect_on_takeoff_and_landing_speeds

The point is you'd have to quadruple your wing loading to double your
cruise/stall/sink speeds for a given angle of attack or trim point. In a flex
wing heavier pilots cause more washout of everything and affect the trim point,
so its common to move the hang point forward for the larger pilots if the glider
trims too slow.

Here's a table I threw together with the basic equation for flight speed (could
be stall, cruise, sink rate in this case). I assumed a 175 lb pilot with 25 lbs
of gear on a 75 lb wing that normally gets a 200 fpm min sink rate and stalls at
20 mph. If this pilot added 14 lbs of weight (equipment, ballast, body weight)
he would theoretically only see another 5 fpm in sink rate, and negligible
change in his stall speed. His best glide speed would go up by the same factor,
which would be an advantage on strong days - exactly what the ballast carrying
is all about. No change in L/D really, just everything is sped up.