An ultralight trike is a type of powered hang glider where flight control is by weight-shift. These aircraft have a fabric flex-wing from which is suspended a tricycle fuselage pod driven by a pusher propeller. The pod accommodates either a solo pilot, or a pilot and a single passenger. Trikes grant affordable, accessible, and exciting flying, and have been popular since the 1980s. Trikes are classified as microlights in Europe, and as light-sport aircraft in the United States. The aircraft are also known by other names, including 2-axis microlights, flex-wing trikes, microlight trikes, deltatrikes or motorized deltaplanes. In the United States, they are formally recognized by the Federal Aviation Administration (FAA) as weight-shift-control aircraft. History The history of the trike is traced back to the invention of Francis Rogallo's flexible wing and subsequent development by the Paresev engineering team's innovations and then others. On 1948, engineer Francis Rogallo invented a self-inflating wing which he patented on March 20, 1951, as the Flexible wing. In 1957, Rogallo released his patent to the government and with his help at the wind tunnels, NASA began a series of experiments testing Rogallo's wing – which was renamed Para Wing – in order to evaluate it as a recovery system for the Gemini space capsules and recovery of used Saturn rocket stages. F. Rogallo's team adapted and extended the totally flexible principle into semi-rigid variants. This mainly involved stabilizing the leading edges with compressed air beams or rigid structures like aluminum tubes. By 1960, NASA had already made test flights of a powered heavily framed cargo aircraft called the Ryan XV-8 or Fleep (short for 'Flying Jeep') and by March 1962, of a weight-shift experimental glider called Paresev. By 1967, all Para Wing projects were dropped by NASA in favor of using round parachutes without officially considering development of personal ultralight gliders, but the airfoil's simplicity of design and ease of construction, along with its capability of slow flight and its gentle landing characteristics, did not go unnoticed by hang glider enthusiasts. The challenge then, was to modify and fit a Rogallo flexible wing with an appropriate frame to allow it to be used as a hang glider. Some modern Rogallo flexible-winged aircraft A crucial development toward the trike was introduction of several mechanical innovations developed by the Paresev and the Fleep engineers; they proved the Rogallo wing suitable for free-flight gliding, powered and unpowered,