The Lycoming XH-2470 was an

H engine An H engine is a piston engine comprising two separate flat engines (complete with separate crankshafts), most often geared to a common output shaft. The name "H engine" is due to the engine blocks resembling a letter "H" when viewed from the fr ...

for aircraft designed and developed by

Lycoming Engines Lycoming Engines is a major American manufacturer of aircraft engines. With a factory in Williamsport, Pennsylvania, Lycoming produces a line of horizontally opposed, air-cooled, four, six and eight-cylinder engines including the only FAA-certi ...

in the 1930s. Although the engine was flown in an aircraft, it was not fitted to any aircraft selected for production. It was derived from the Lycoming O-1230 engine.

Design and development

In 1932, the engineers at Lycoming Engines became aware that the

United States Army Air Corps The United States Army Air Corps (USAAC) was the aerial warfare service component of the United States Army between 1926 and 1941. After World War I, as early aviation became an increasingly important part of modern warfare, a philosophical r ...

(USAAC) wanted a high-performance engine that could produce at least one

horsepower Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are the ...

per cubic inch (46 kW/L) of engine displacement.White p. 379 Determined to become known as a high-performance engine manufacturer, Lycoming began an experimental, high-performance engine of its own. After spending US $500,000, and after many attempts to develop a successful engine, it finally came close to the USAAC specifications with the O-1230 engine, which was a 12-cylinder liquid-cooled horizontally opposed low-profile piston engine.White p. 380 In 1936, the single-cylinder development tests exceeded expectations, passing its 50-hour test requirement. The full-size engine was ready for testing in 1937, and was rated at 1,000 hp. Continued development of the O-1230 reached its peak when the engine was rated at over 1,200 hp (895 kW). The O-1230 was not well received by aircraft manufacturers, because it was not very reliable at that power setting. It was apparent that the O-1230 engine was uncompetitive with the high-performance air-cooled engines that were then becoming available. The US Navy began funding the development of the Lycoming engine.Balzer p. 24 The funding enabled Lycoming's engineers to attempt rescuing the design by proposing a 24-cylinder H-configuration engine made by stacking two of the O-1230 engines, gearing them together to one common output shaft. The new engine was the H-2470. It weighed in at 2,430 pounds and produced 2,300 hp (1,700 kW) at 3,300 rpm.

Operational history

The Navy specified the H-2470 for the Curtiss XF14C-1 experimental fighter. After some rigorous testing the engine's poor performance led to the substitution, before the aircraft flew, of a

Wright R-3350 The Wright R-3350 Duplex-Cyclone is an American twin-row, supercharged, air-cooled, radial aircraft engine with 18 cylinders displacing nearly . Power ranged from 2,200 to over 3,700 hp (1,640 to 2,760 kW), depending on the model. ...

radial engine, which was also having technical problems but was considered to be more reliable than the H-2470. The testing program was eventually terminated due to the poor performance of the aircraft.White p. 381 The USAAC was also interested in the H-2470, and installed and flew it in the

Vultee XP-54 The Vultee XP-54 ''Swoose Goose'' was a prototype fighter built by the Vultee Aircraft Company for the United States Army Air Forces (USAAF). Design and development Vultee submitted a proposal in response to a U.S. Army Air Corps request for ...

prototype fighter. The XP-54 was the only aircraft to actually use it for flight, but like the Navy's XF-14C, the XP-54 never went into production.

Applications

Intended

Curtiss XF14C The Curtiss XF14C was an American naval fighter aircraft. It was developed by Curtiss-Wright in response to a request by the United States Navy in 1941 to produce a new shipboard high-performance fighter aircraft. Design and development In 19 ...

* Northrop N-1

Specifications

References

* White, Graham, ''Allied Aircraft Piston Engines of World War II'', SAE International, 1995 * Balzer, Gerald C., ''American Secret Pusher Fighters of World War II'', Specialty Press. 2008 * Wagner, Ray, ''American Combat Planes'', Third Enlarged Edition, Doubleday, 1982. * Wegg, John, ''General Dynamics Aircraft and Their Predecessors'', Naval Institute Press, 1990.

External links

XH-2470 in a test cell
{{Aeroengine-specs H-2470 1930s aircraft piston engines Abandoned military aircraft engine projects of the United States H engines