Australian Bill Bennett helped promote hang gliding in the late 1960s and early 1970s. Bennett's first gliders were kites for water skiers, such as the Model 162. He based these designs on a flexible wing that Francis Rogallo evaluated while working for the National Aeronautics and Space Administration (NASA). The space agency wanted to develop a recovery system for Gemini and Apollo capsules (see NASM collection) that allowed astronauts to steer the capsule to a landing as an alternative to unguided parachutes. The difficulties the agency experienced trying to recover the Mercury capsules (see NASM collection), and the near tragedy that followed Gus Grissom's splashdown in July 1961, no doubt encouraged NASA to develop alternative capsule recovery systems that gave astronauts more control over where they landed.
NASA and several aerospace companies experimented with Rogallo wings from 1961 to 1965. NASA built and tested the Parasev (or Paraglider Research Vehicle, see NASM collection) research vehicle from 1962 to 1964. The concept used a Rogallo wing but was eventually discarded in favor of recovering spacecraft with simpler, more reliable and more economical parachutes. Publicity from NASA’s experimental work sparked interest among enthusiasts such as Australian Bill Bennett to evaluate the Rogallo flexible wing.
Australian John Dickenson gets too little credit for his monumental breakthrough to invent the technology that allowed pilots to precisely control a hang glider. Early in 1963, the Grafton Water Ski Club in New South Wales, Australia, asked Dickenson to build a kite for an upcoming water ski festival. Dickenson studied the classic flat pentagonal-shaped ski kite and noted its dangerous lack of control and stability. After exploring several ideas, he probably saw drawings of NASA’s Rogallo wings published widely in the popular press. NASA had found no reliable way to deploy the Rogallo wing from a spacecraft, but the wing’s simplicity, low cost, and flight stability may have encouraged Dickenson to choose it for his new ski kite. He made and tested models of a Rogallo-type wing and they showed improved stability, but control was little better than the classic ski kite.
Since Lilienthal’s first flights in 1891, pilots had clung to their hang gliders framework and tried to influence the direction of flight by swinging their legs and body to shift their weight in the direction they wanted to go. The pilots were positioned at the center of the wing and their range of movement was limited by the airframe enclosing them. Control was feeble at best.
While swinging his daughter sideways on a swing set in 1963, Dickenson had the flash of insight that gave pilots precise control and transformed the hang glider. Dickenson’s idea was brilliant and simple, and added little weight. It consisted of a control bar and a seat or harness suspended from the keel tube by a strap. He bolted the control bar directly to the overhead keel tube of the glider and just behind the control bar, and braced it with wires attached to the wing tips. From the hanging strap, he suspended the pilot’s seat. The strap supported the pilot like a pendulum and allowed him or her to shift their weight with ease, pushing and pulling the control bar to make the glider climb, dive, or turn.
Dickenson tested the controls on a half-size flexible Rogallo-type wing too small to fly. The tests were promising so Dickenson built a kite large enough to lift a person. On September 8, 1963, as John Dickenson looked on, a ski boat towed his friend Rod Fuller aloft for the first flight of a Rogallo-type wing ski kite with the improved Dickenson control system. By 1966, Dickenson was selling his adaptation of the Rogallo-type wing ski kite fitted with his new control system, and in 1967, he introduced fellow Australian Bill Bennett to the booming sport of flying ski-kites. Bennett quickly set altitude records in hang gliders equipped with Dickenson's control system. By 1969, Bennett had moved to California to sell commercial models under the Delta Wing Kites and Gliders brand name. The excitement of flying and the ease of access to flight provided by the Rogallo wing with Dickenson control appealed to the freewheeling sport leisure culture of the late 1960s, and across America, Bennett's kites grew in popularity.
Bennett's early Rogallo designs consisted of two high-strength, heat-treated, anodized aluminum tubes bolted together to form a cross, one a cross bar and the other a keel tube. Two aluminum tubes were bolted to one end of the keel tube to form the two leading edges of a delta wing with a relatively narrow convergence angle of 80 degrees. A Dacron 'sail' attached to this frame completed the semi-rigid airfoil. Pilots sat on a Nylon-webbed seat attached to the keel tube. They controlled the aircraft by grasping a control bar fixed to the keel tube and wired to the wing tips, and shifting their weight side-to-side and fore-and-aft beneath the overhead wing.
Bennett produced ten different models of the Rogallo hang glider and named each for the length of the keel tube in inches – 162, 174, 186, 198, and 210 inches. Gliders with longer keel tubes also had leading edge tubes of greater span and larger wing areas that could lift heavier pilots. The Model 162 could safely support a pilot weighing only 59 kg (130 lb), while the Model 210 could accommodate a pilot weighing up to 113 kg (250 lb).
Enthusiasm for hang gliding continued to increase and pilots posted new duration and altitude records in rapid succession. Bennett developed five lighter variations of the tow-kites specifically adapted for foot launching. The Rogallo wings with 80 or 90-degree nose angles became known as standard Rogallos. Soon the modified, or hybrid Rogallo, appeared. These gliders had higher nose angles and longer wingspans. As before, steel wires braced the whole structure to increase strength and improve performance. This version proved much safer than the standard Rogallos, which could be unstable in moderate winds and turbulence. On the early standards, the sails attached to the leading edges and keel tube only, leaving large areas of material loose. All was well if the pilot maintained stable forward flight. The swept leading edges created vortexes that billowed the sail into a stable concave shape. But in turbulence or during a stall, one or both sides of the wing could deflate and collapse, or 'luff,' causing the glider to drop out of control. With more pilots foot-launching off of high rough terrain, hang gliding injuries and fatalities rose, accelerating the transition to modified Rogallo designs.
Most hang glider pilots had begun flying modified Rogallos after 1975. Bennett introduced the Phoenix series of hang gliders (see NASM collection) and these and other modified Rogallo gliders allowed pilots to fly farther and more safely. Bennett donated a Model 162, along with a number of modified Rogallo hang gliders to the National Air and Space Museum in 1984. Nothing is known about the flight history of the Delta Wing Model 162 on display.
