The XP-13 Viper was a prototype

biplane A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While ...

fighter aircraft Fighter aircraft are fixed-wing military aircraft designed primarily for air-to-air combat. In military conflict, the role of fighter aircraft is to establish air superiority of the battlespace. Domination of the airspace above a battlefield ...

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...

company

Thomas-Morse Aircraft Corporation The Thomas-Morse Aircraft Corporation was an American aircraft manufacturer, until it was taken over by the Consolidated Aircraft, Consolidated Aircraft Corporation in 1929. History Founded in 1910 by English immigrants William T. Thomas and hi ...

. The airplane was delivered to the

United States Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...

in 1929, but they did not adopt it.

Design and development

Thomas-Morse XP-13 - Ray Wagner Collection Image (16573609412)

This aircraft was one of several

B. Douglas Thomas B is the second letter of the Latin alphabet. B may also refer to: Science, technology, and mathematics Astronomy * Astronomical objects in the Barnard list of dark nebulae (abbreviation B) * Latitude (''b'') in the galactic coordinate syste ...

designs built in hopes of a production contract from the Army, following the successful Thomas-Morse MB-3 of 1919. Financed by the company, and named the "Viper", it was officially purchased by the Army in June 1929 and designated "XP-13". The XP-13

fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...

had a corrugated

aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has ...

skin built over a metal frame; the flying surfaces were also metal-framed, but covered with the traditional fabric. While designed to use the 600 hp Curtiss H-1640-1 Chieftain engine, (a novel 12-cylinder two-row air-cooled radial with the rear cylinders directly behind the front cylinders rather than staggered as normal in a two-row radialGunston 1986, p.46.) for which the XP-13 incorporated a complex system of baffles to direct cooling air over the engine, the engine simply would not stay cool enough, and in September 1930 it was replaced with a Pratt & Whitney SR1340C Wasp of 450 hp. Ironically, the lower-power engine actually resulted in a speed increase of 15 mph, at least partly because of the weight savings. In the end, the Army decided against production, Thomas-Morse was acquired by

Consolidated Aircraft The Consolidated Aircraft Corporation was founded in 1923 in aviation, 1923 by Reuben H. Fleet in Buffalo, New York, the result of the Gallaudet Aircraft Company's liquidation and Fleet's purchase of designs from the Dayton-Wright Company as the ...

, and the prototype was lost to an inflight fire.

Variants

;XP-13 :Prototype, serial number 29-453 with 600 hp (448 kW) Curtiss H-1640-1 Chieftain hex engine ;XP-13A :The XP-13 modified with a 525 hp (391 kW) Pratt & Whitney SR-1340-C enclosed in a

NACA cowling The NACA cowling is a type of aerodynamic fairing used to streamline radial engines installed on airplanes. It was developed by Fred Weick of the National Advisory Committee for Aeronautics (NACA) in 1927. It was a major advance in aerodynamic ...

, along with a revised

fin A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fin ...

and

rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other vehicle that moves through a fluid medium (generally aircraft, air or watercraft, water). On an aircraft the rudder is used primarily to ...

"The American Fighter", Enzo Angellucci and Peter Bowers, (Orion Books ), 1987 ;XP-14 :This designation was used for a proposed

Curtiss Curtiss Aeroplane and Motor Company (1909 – 1929) was an American aircraft manufacturer originally founded by Glenn Hammond Curtiss and Augustus Moore Herring in Hammondsport, New York. After significant commercial success in its first decade ...

version of the Viper with the Curtiss H-1640-1 Chieftain hex engine

Operators

; *

United States Army Air Service The United States Army Air Service (USAAS)Craven and Cate Vol. 1, p. 9 (also known as the ''"Air Service"'', ''"U.S. Air Service"'' and before its legislative establishment in 1920, the ''"Air Service, United States Army"'') was the aerial war ...

Specifications (XP-13 (Chieftain engine))

References

;Notes ;Bibliography * Dorr, Robert F. and David Donald. ''Fighters of the United States Air Force''. London:Temple, 1990. . * Gunston, Bill, ''World Encyclopedia of Aero Engines''. London: Guild Publishing, 1986.

External links