Grumman Goose

G-21/JRF Goose
Role	Transport amphibious aircraft
Manufacturer	Grumman
First flight	1937
Primary users	United States Navy United States Army Air Forces Royal Air Force Royal Canadian Air Force
Number built	345
Unit cost	US$62,180.00 for JRF-6B (1942)

The Grumman G-21 Goose is an amphibious aircraft designed by Grumman to serve as an eight-seat "commuter" aircraft for businessmen in the Long Island area. The Goose was Grumman’s first monoplane to fly, its first twin-engined aircraft, and its first aircraft to enter commercial airline service. During World War II, the Goose became an effective transport for the US military (including the United States Coast Guard), as well as serving with many other air forces. During hostilities, the Goose took on an increasing number of combat and training roles.

In 1936, a group of wealthy residents of Long Island, including E. Roland Harriman, approached Grumman and commissioned an aircraft that they could use to fly to New York City. In response, the Grumman Model G-21 was designed as a light amphibious transport. Grumman produced a high-wing monoplane of almost all-metal construction—the trailing half of the main wing and all of the flight control surfaces except for the flaps were fabric-covered. It was powered by two 450 horsepower (340 kW) Pratt & Whitney R-985 Wasp Junior nine-cylinder, air-cooled, radial engines mounted on the leading edges of the wings. The deep fuselage served also as a hull and was equipped with hand-cranked retractable landing gear. First flight of the prototype took place on May 29, 1937.

The fuselage also proved versatile, as it provided generous interior space that allowed fitting for either a transport or luxury airliner role. Having an amphibious configuration also allowed the G-21 to go just about anywhere, and plans were made to market it as an amphibian airliner.

A number of modifications were made for the Goose, but the most numerous are those by McKinnon Enterprises of Sandy, Oregon, which holds 21 supplemental type certificates (STCs) for modifying G-21-series aircraft and which also manufactured four different conversions that were recertified under a separate FAA type certificate (TC no. 4A24) as brand-new "McKinnon" airplanes. The first was the McKinnon model G-21C which involved replacing the original R-985 radial engines with four Lycoming GSO-480-B2D6 piston engines. It was approved under TC 4A24 on November 7, 1958, and two examples were built in 1958-1959.