Breaking gliding records is difficult, but designers are always trying to glide farther, faster, and higher. You've seen hang glider pilots running into the wind to take off. Hang gliders need a total airspeed of 20 mph to take off. Decrease the angle of attack, and the glider dives and speeds up. Increasing the angle of attack slows the glider.
Ground speed is a result of airspeed and wind speed.
This makes thermals rise more rapidly, offering more lift for gliders. Hang gliding for beginner pilots. Sports Illustrated, pp. Los Angeles Times, p. 6. Popular Science, pp.