a brief history of parachutes, airfoils and slope soaring
In the late 15th century, Leonardo da Vinci anticipated a safety device for people to use as a last means of escape from tall buildings on fire. His sketches depicted an apparatus with material pulled tightly over a rigid pyramid shaped frame. A century later another Italian, Fausto Veranzio, published Machinae Nova, a book about devices of his own design. It contained an engraving titled Homo Volans (Flying Man), the first printed depiction of a parachute device in use.
In 1783, Louis Sebastien Lenormand publicly demonstrated the principle by jumping safely from a tower using a 14 ft diameter parachute. In 1785, Jean Pierre Blanchard was the first to use a parachute as an emergency system after his hot air balloon exploded over France, and in 1797, Andrew Garnerin made the first jump with a parachute that contained no rigid structure.
The next major contribution to parachute systems came in 1887 when Captain Thomas Baldwin developed the harness. In 1890, Paul Letteman and Kathchen Paulus developed the idea of packing the parachute in a knapsack. Paulus also demonstrated the first intentional cutaway and reserve deployment by carrying two chutes. In 1914, Georgia 'Tiny' Broadwick made the first freefall jump and in 1919, Leslie Irvin and Floyd Smith developed the ripcord at the Parachute Testing and Training Centre, Wright Field (established in 1918).
By the 1920's, parachutes were primarily used by the military forces of Germany, Russia and the USA. The concept of airborne infantry and paratroopers served a military purpose and from 1930 onwards, developments on the conventional Solid Cloth (round silk) parachute gave rise to models with greater military applications, models like the Ribbon parachute, the Ring Slot parachute, the Ring Sail parachute, the Guide Surface parachute and the Hyperflo parachute.
Sport parachutes beyond solid cloth began to appear in the early 60's. Greater stability and horizontal speed were achieved by modifying round canopies to include drive slots, giving rise to a new class of sport parachute, High Performance Rounds, which includes the Piglet parachute, the Sierra parachute and the Papillon parachute (the later two with a pulled apex). Pierre Lemoigne produced the designs that lead to the the Para Commander (PC) parachute in the 60's, with numerous cut outs and slots giving improved forward speed and stability. Lemoigne's design, although popular with parachutists, was later derived for parasailing, the canopy towed aloft by a line behind a boat, very popular at beach resorts.
Meanwhile, development of the airfoil section had begun in the mid to late 1800's. It had always been known that a flat surface produced deflective lift if set at an angle of incidence to the air flow, but some were beginning to suspect that concavo-convex shapes that more closely resembled a bird's wing would produce more efficient lift. So much so that in 1884, Horatio F. Phillips patented a series of airfoil shapes after testing them in one of the earliest wind tunnels.
In his 1894 book, Bird Flight as the Basis of Aviation, Otto Lilienthal (1848-1896) held that the key to successful flight was wing camber. He also experimented with different leading edge radii and thickness distributions. It seems the Wright Brothers were suitably impressed, they used airfoils closely resembling Lilienthal's thin and highly cambered designs in their flying machines. Early tests of airfoils were modelled using a low Reynold's number where thin sections are more efficient than thicker sections. One possible reason why most of the first aircraft were biplanes.
As early as the 1940's, Francis Rogallo began experimenting with unbraced kites and designed a single surface flexible delta shaped parachute, the Parawing. Designed for maximum lift as opposed to maximum drag, the Parawing was primarily used by sport parachutists during the early 70's. Rogallo produced some very effective kite designs in his time that eventually led others to produce the delta shaped hang-glider, complete with rigid framework.
In 1963 Domina Jalbert patented the Parafoil, a double surfaced rectangular canopy formed from sectioned cells in an airfoil shape and inflated via passage through the air. The technology became know as the "ram-air" system and forms the basis of all paraglider design.
Walter Newmark, a sailplane pilot, later wrote a manual, Operational Procedures for Ascending Parachutes, and towing ram-air parachutes became the passion of a group who formed the British Association of Parascending (BAPC) in the early 70’s.
In 1965 whilst working for NASA, David Barish designed a parachute to safely bring Apollo space capsules back to earth. His Sailwing design was a single surface gliding parachute with a large defined leading edge. In wind tunnel tests, his parachute design was measured to have a glide ratio of 4.2.
The Barish Sailwing was later manufactured commercially by Parachutes Inc. in the USA and in 1972, Aerofoil Systems Inc. introduced the Parasled, a parachute modelled after Jalbert's Parafoil design. By early to mid 1970, most sport parachutists had replaced their single membrane canopies with double surfaced ram-air parachutes.
In 1972, the Parachute Manual, a magazine for professional parachutists, featured an article on Slope Soaring, described as "a method of foot launching a ram-air parachute for testing after repair". In his 1973 book, Hang Gliding, Dan Poynter described paragliding as being very similar to hang gliding and identified the promoter of slope soaring, David Barish, as having already made numerous demonstration glides with his modified Sailwing canopy at several US ski resorts.
By 1980, a small number of parachutists (including André Bohn) were regularly foot launching their ram-air parachutes from the foothills of the French and Swiss Alps and gliding down to the valleys below. Slope soaring quickly grew in popularity to the point where in the mid 80's, Ailes de K (founded by a Swiss sailmaker, Laurent de Kalbermatten) began to release the first commercially available paragliders... and it just took off from there!