The first aircraft Sisler designed and built was the Pipit two-seater, later owned by another pilot. It was followed by the SF-2 Whistler, which gained the 'Outstanding Design Contribution' award at the 1973 EAA Fly-in at Oshkosh. Sisler subsequently improved this design, making it easier to build, aerodynamically cleaner and 23 kg (50 lb) lighter. Plans of the improved version, then known as the SF-2A Cygnet, became available to other constructors.
The side-by-side two-seat light aircraft had wings of wood construction with Dracon covering, the fuselage and tail unit had a welded chrome molybdenum steel tube structure, also Dacron-covered. Powerplant was a modified 62 hp 1,834 cc Volkswagen motor car engine.
Span: 30 ft 0 in (9.14 m)
Length: 19 ft 0 in (5.79 m)
Height: 5 ft 10 in (1.78 m)
Wing area: 124.8 sq.ft (11.60 sq.m)
Weight empty: 585 lb (265 kg)
Loaded weight: 1,100 lb (499 kg)
Max speed: 108 mph (174 kmh)
Cruise speed: 87 mph (161 kmh) at 8,000 ft (2,440 m)
Climb: 580 ft (177 m)/min