The Curtiss Model 55 Kingbird was an airliner built in small numbers in the United States in the early 1930s. It was a twin-engine aircraft with a fuselage derived from the single-engine Curtiss Model 56 Thrush. The Kingbird mounted two engine nacelles in the struts on either side of the fuselage that braced the wing and the outrigger undercarriage. A distinctive design feature was the aircraft's blunt nose, located behind the propeller arcs. This allowed the engines to be mounted closer to each other and to the aircraft's centerline, therefore minimising asymmetrical thrust in case of an engine failure. For the same reason, the Thrush's single tailfin was replaced by twin tails on the Kingbird, and the main production model, the D-2 fitted a second horizontal stabilizer and elevator between these fins.
Eastern Air Transport was to be the Kingbird's main operator, flying 14 of them for a few years. The United States Marine Corps also purchased an example, first designating it JC-1, then RC-1 and using it as an air ambulance.