Lycoming XH-2470

{{Short description|Aircraft engine developed by Lycoming Engines}}  {{infobox aero engine | name= XH-2470 | image= | caption= Lycoming XH-2470-7 |engine_type= [[H engine]] |manufacturer= [[Lycoming Engines]] |designer= |national_origin= United States |first_run= 1940 |major_applications= [[Vultee XP-54]] |produced= |number_built= |developed_from= [[Lycoming O-1230]] |variants_with_their_own_articles= }}

The '''Lycoming XH-2470''' was an [[H engine]] for aircraft designed and developed by [[Lycoming Engines]] 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]] (USAAC) wanted a high-performance engine that could produce at least one [[horsepower]] per cubic inch (46 kW/L) of engine displacement.<ref name="White379">White p. 379</ref> 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.<ref name="White380">White p. 380</ref> 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.<ref name="White380"/>

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.<ref name="Balzer">Balzer p. 24</ref> 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.<ref name="White380"/>

==Operational history== The Navy specified the H-2470 for the [[Curtiss XF14C|Curtiss XF14C-1]] experimental fighter.<ref name="White380"/> After some rigorous testing the engine's poor performance led to the substitution, before the aircraft flew, of a [[Wright R-3350]] 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.<ref name="White381">White p. 381</ref>

The USAAC was also interested in the H-2470, and installed and flew it in the [[Vultee XP-54]] 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.<ref name="White380"/>

==Applications== * [[Vultee XP-54]]

=== Intended === *[[Curtiss XF14C]] *[[Northrop N-1]]

==Specifications== {{pistonspecs|   |ref= |type=24-cylinder, 'H' piston engine |bore=5.25 in. (133.35 mm) |stroke=4.75 in. (120.65 mm) |displacement=2467.8 cu in (40.44 L) |length= |diameter= |width= |height= |weight=2,430 lb (1,102 kg) |valvetrain=[[Overhead camshaft engine|Dual overhead camshafts]] (DOHC) with four valves per cylinder |supercharger=Single-speed, single-stage (two-speed on the -5 variant) |turbocharger= |fuelsystem=Carburetor (with potential for gasoline injection in testing) |fueltype=100/130 [[octane]] gasoline |oilsystem= |coolingsystem=Liquid-cooled |power=2,300 hp at 3,300 rpm |specpower= |compression=6.5:1 |fuelcon= |specfuelcon= |oilcon= |power/weight=

|designer= |reduction_gear=

|general_other= |components_other= |performance_other= }}

==See also== {{aircontent  |see also=

|related=

|similar aircraft=

|lists= *[[List of aircraft engines]]  |similar engines= * [[Fairey Monarch|Fairey P.24]] * [[Napier Sabre]]

}}

==References== {{Reflist}}

* 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== * [http://postfiles7.naver.net/data44/2009/1/5/166/result_2009_0_1_11_9_40_656_2-naljava69.jpg?type=w2 XH-2470 in a test cell]

[[Category:Lycoming aircraft engines|H-2470]] [[Category:1930s aircraft piston engines]] [[Category:Abandoned military aircraft engine projects of the United States]] [[Category:H engines]] [[Category:24-cylinder engines]] [[Category:Liquid-cooled aircraft piston engines]]