The Bug2 airchair biplane (or sesquiplane) first flew in Februauy of 1999. Bug 4 was intended to be an improved version of Bug2, and was considered superior.
The monoplane airchairs were a furthur development of the Bug4. Construction is of aluminum tubing and steel cable covered with a heat shrunk fabric.
Safety design aspects include:
Extensive frangible structure around the pilot for crash impact protection
4 point safety belts
A hand deployed emergency parachute which is intended to bring the glider and pilot down together, tail first, so that the pilot is protected by the tail and wing structure during the parachute landing
Construction of the Bug wheeled sailplane is from readily available materials without special welding, machining, or molds. The empty weight, for a not foot launchable glider, is substantially less than the ultralight regulatory weight limit; about the same weight as the pilot.
Quick assembly & roof rack transport make flying convenient. A Bug or Goat can be strapped down onto an ordinary hang glider rack, with no special saddles or pads.
Bug2 and Bug4 have demonstrated casual and comfortable airchair soaring, drogue chute landings in small fields, and novice instruction on training hills. They have been towed by trucks, winches, and ultralight airplanes. The Bugs have soared high, if not far, and have always returned for a safe landing. An airchair can be launched by ultralight aerotow, car tow, winch cable, or just by rolling down an open slope.
Accomplishments of these biplanes include:
Self launch soaring by rolling down hillsides
Self launch training by rolling down hillsides
Car top transport on non-specialized racks
The Bugs fly at about the same speeds as a hang glider, readily mixing with hang glider and paraglider traffic. No formal performance measurements have been made, but all are in the hang glider range and can stay up in good lift conditions. The Bug has soared thousands of feet above take off altitude.
Sandlin has flown the Bug2 and Bug4 for soaring only, not aerobatics. He considers the structural redline (maximum safe airspeed) for flying to be 45 mph.
Bug2 and Bug4 performance has not been measured but seems to be about the same as a single surface hang glider. As of April 2010 only a single Bug4 is known to be currently flying .
Posting of the complete technical drawings of an aircraft on the Internet, freely available in the public domain for downloading and study.