The Viking SF-2A Cygnet, also called the Sisler SF-2A Cygnet and the HAPI SF-2A Cygnet, is an American

STOL A short takeoff and landing (STOL) aircraft is a conventional fixed-wing aircraft that has short runway requirements for takeoff and landing. Many STOL-designed aircraft also feature various arrangements for use on airstrips with harsh conditio ...

amateur-built aircraft Homebuilt aircraft, also known as amateur-built aircraft or kit planes, are constructed by persons for whom this is not a professional activity. These aircraft may be constructed from "scratch", from plans, or from assembly kits.Armstrong, Kenn ...

, designed by Bert Sisler and produced by

Viking Aircraft LLC Viking Aircraft LLC is an American aircraft manufacturer based in Elkhorn, Wisconsin. The company specializes in the provision of homebuilt aircraft plans for amateur construction.Purdy, Don: ''AeroCrafter - Homebuilt Aircraft Sourcebook, Fi ...

. The aircraft is supplied in the form of plans for amateur construction. The Cygnet first flew in 1973.Purdy, Don: ''AeroCrafter - Homebuilt Aircraft Sourcebook'', page 285. BAI Communications, 15 July 1998. Downey, Julia: ''2003 Plans Aircraft Directory'', Kitplanes, Volume 20, Number 1, January 2003, page 29. Primedia Publications. The Cygnet plans were originally marketed by the designer through his company Sisler Aircraft of

Bloomington, Minnesota Bloomington is a suburban city in Hennepin County, Minnesota, on the north bank of the Minnesota River, above its confluence with the Mississippi River, south of downtown Minneapolis. As of the 2020 census, the city's population was 89,987, ma ...

and later by HAPI Engines, a supplier of

Volkswagen air-cooled engine The Volkswagen air-cooled engine is an air-cooled, gasoline-fuelled, boxer engine with four horizontally opposed cast-iron cylinders, cast aluminum alloy cylinder heads and pistons, magnesium-alloy crankcase, and forged steel crankshaft and co ...

s. By the 1990s Viking Aircraft of Elkhorn, Wisconsin took over supplying the aircraft plans.

Design and development

The SF-2A Cygnet is a development of the earlier Sisler SF-2 Whistler introduced in 1973. The design features a

strut-braced In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of strut, which act in ...

shoulder-wing A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing confi ...

, a two-seats-in-

side-by-side configuration Tandem, or in tandem, is an arrangement in which a team of machines, animals or people are lined up one behind another, all facing in the same direction. The original use of the term in English was in ''tandem harness'', which is used for two ...

enclosed cockpit under a bubble canopy, fixed

conventional landing gear Conventional landing gear, or tailwheel-type landing gear, is an aircraft undercarriage consisting of two main wheels forward of the center of gravity and a small wheel or skid to support the tail.Crane, Dale: ''Dictionary of Aeronautical Term ...

and a single engine in tractor configuration. The aircraft is made from wood,

4130 steel 41xx steel is a family of SAE steel grades, as specified by the Society of Automotive Engineers (SAE). Alloying elements include chromium and molybdenum, and as a result these materials are often informally referred to as chromoly steel (common ...

tubing and covered in doped aircraft fabric. Its span wing employs a NACA 3413

airfoil An airfoil (American English) or aerofoil (British English) is the cross-sectional shape of an object whose motion through a gas is capable of generating significant lift, such as a wing, a sail, or the blades of propeller, rotor, or turbine. ...

, has an area of and is supported by a single strut with a

jury strut In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of strut, which act in c ...

. The cockpit is wide and has a baggage compartment with a limit of , located behind the seats. The aircraft's recommended engine power range is and standard engines used include the Volkswagen

four-stroke A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directio ...

powerplant. Construction time from the supplied kit is estimated as 1700–1800 hours. The Cygnet won a design award at the EAA Annual Convention and Fly-In in 1973.

Operational history

By January 2003, 100 examples had been reported as completed and flown. In July 2016 a total of 19 SF-2A Cygnets were registered in the United States with the

Federal Aviation Administration The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic m ...

, four with

Transport Canada Transport Canada (french: Transports Canada) is the department within the Government of Canada responsible for developing regulations, policies and services of road, rail, marine and air transportation in Canada. It is part of the Transportati ...

and seven with the

Civil Aviation Authority A civil aviation authority (CAA) is a national or supranational statutory authority that oversees the regulation of civil aviation, including the maintenance of an aircraft register. Role Due to the inherent dangers in the use of flight vehicles, ...

in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

. In a 2020 review, AVweb writer Paul Dye concluded, "Flying a piece of history (and with a forward swept wing, something fairly unique!) is always fun. Just like all strange meat gets described as "tasting like chicken", it is easy to describe airplanes like this as flying "like a Cub"—and it’s true, in the sense that it is well-mannered and easy to steer around the sky. Yes, that visibility at the start of a turn is going to take a little getting used to, as is the landing attitude. But if you take the time to get it figured out, the Cygnet is a nice little airplane with a Midwest tradition. Honest, straightforward, and enjoyable.".

Specifications (SF-2A Cygnet)

References

External links

* {{Viking Aircraft Homebuilt aircraft Single-engined tractor aircraft