Glider polars
Still-air speed polars for three full-size sailplanes. Click anywhere on a curve to select that point and see its airspeed and glide ratio.
Click anywhere on a curve to inspect that point. The buttons select each glider at best glide.
How to read it: sink rate is plotted downwards, as is conventional for a glider polar. Clicking a curve fixes the blue line and marker at that point. The line's data slope gives V / sink after converting km/h to m/s.
These are idealized curve fits at a reference loading, not universal aircraft performance. Mass, air, bugs and the individual aircraft move the polar—do not use this visualization for flight planning.
Sources: ASK 21 specifications, LS4 performance summary, Duo Discus XL, and the three-point XCSoar polar store (LS4 at 361 kg; Duo Discus xT at 700 kg, used here as an XL approximation).