Viking SF-2A Cygnet

SF-2A Cygnet
Role Amateur-built aircraft
National origin United States
Manufacturer Viking Aircraft LLC
Designer Bert Sisler
First flight 1973
Introduction 1973
Status Plans available (2003)
Number built 100 (2003)
Developed from Sisler SF-2 Whistler

The Viking SF-2A Cygnet, also called the Sisler SF-2A Cygnet and the HAPI SF-2A Cygnet, is an American STOL amateur-built aircraft, designed by Bert Sisler and produced by Viking Aircraft LLC. The aircraft is supplied in the form of plans for amateur construction. The Cygnet first flew in 1973.

The Cygnet plans were originally marketed by the designer through his company Sisler Aircraft of Bloomington, Minnesota and later by HAPI Engines, a supplier of Volkswagen air-cooled engines. By the 1990s Viking Aircraft of Elkhorn, Wisconsin took over supplying the aircraft plans.