The Cosmos Bison, also called the Cosmos Bidulm, is a French two-seat, ultralight trike that is produced by Cosmos ULM. The aircraft is only supplied as a completed aircraft and is not available as a kit.^[1]

Design and development

The Bison was designed to comply with the European Fédération Aéronautique Internationale microlight classification. It features a cable-braced hang glider-style high-wing, weight-shift controls, a two-seats-in-tandem open cockpit, tricycle landing gear and a single engine in pusher configuration.^[1]

The aircraft wing is made from bolted-together aluminum tubing and covered in Dacron sailcloth. A number of different wings are available for the Bison. The wing is supported by a single tube-type kingpost and uses an "A" frame control bar. Optional equipment includes a cockpit fairing and wheel pants. Engines used are the 37 kW (50 hp) Rotax 503 and 30 kW (40 hp) Rotax 447 twin cylinder, two-stroke powerplants. The landing gear is cable-braced, which allows a folding design for ground transport or storage.^[1]

The Bison was later developed into the Cosmos Phase II, by adding larger seats, new landing gear shock absorbers and a redesigned engine mount to reduce vibration. In 2012 the Bison remained in production alongside the Phase II and Phase III, offering a simpler, lighter and less expensive two seater than the newer models.^[1]

Specifications (Bison)

Data from Bertrand^[1]

General characteristics

• Crew: one
• Capacity: one passenger
• Wingspan: 10.6 m (34 ft 9 in)
• Wing area: 19 m² (200 sq ft)
• Empty weight: 123 kg (271 lb)
• Gross weight: 400 kg (882 lb)
• Fuel capacity: 40 litres (8.8 imp gal; 11 US gal)
• Powerplant: 1 × Rotax 447 twin cylinder, air-cooled two-stroke aircraft engine, 30 kW (40 hp)
• Propellers: 2-bladed wooden

Performance

• Maximum speed: 85 km/h (53 mph, 46 kn)
• Cruise speed: 60 km/h (37 mph, 32 kn)
• Stall speed: 40 km/h (25 mph, 22 kn)
• Rate of climb: 2.5 m/s (490 ft/min)