The original version of themodern hang glider was patented in 1951 by an American, Francis M. Because longer wings reduce this turbu lence,some high ‑ performance hang gliders now have wingspans greaterthan thirty feet. The air also forms tiny eddies at the wing's tips and edge,creating more drag and decreasing lift. The leading edge of the wing, the pilot,and other surfaces on the glider impede flight by disturbing the air flowingover the glider. The greatest obstacles toflight and lift are gravity and drag. Modern hanggliders, which cost around $2,000, offer glide ratios up to eleven to one. That is, for every four feetof horizontal flight in stable air, the glider will sink one foot. The billowing belly of akite-like, diamond ‑ shaped Rogallo hang glider performs best at nineteenmiles per hour, with a glide ratio of four to one. The swept ‑ back wings of an F ‑ 16 are designedto achieve maximum performance at supersonic speeds. This lowers pressure above the wingrelative to that below it, creating lift. Because of the curvature of the upper surface, air passing over the wing must travel farther and movefaster than air passing under the wing. The wing cleaves the air, causing it to pass both over and under thewing's surfaces.
The underlying principles of hang ‑ gliding aerodynamics are the same as for any otheraircraft. In the unforgiving world of the air, function follows form ‑ exactly.
Like sailboats, hang gliderscome in an array of shapes and sizes and perform differently in differentwinds. A quick charge into the wind and thesemodern ‑ day Daeda luses rise into thesky and begin their search for elevator updrafts that can take them miles fromEarth. From New Hampshire to New Zealandon any day when the winds are right, thousands of pilots assemble theirmulticolored wings, clip in their flying harnesses, and step to the edges ofcliffs, dunes, and mountain peaks. Today's hang ‑ glider pilots have surpassed the most goggle ‑ eyed dreams of their tower ‑ jumping forebears. Long on faith butshort on aerodynamics, the few "tower jumpers" who survived werecarted away with no desire to try again. When crazed monks and princesleaped from their castles and cathedrals in the Middle Ages gripping undersizedwings made of sticks and cloth, they met with little success.