Continental I-1430

I-1430
I-1430-9 in the National Museum of the United States Air Force
Type	Piston aircraft engine
Manufacturer	Continental Motors
First run	1939
Major applications	Lockheed XP-49 McDonnell XP-67
Number built	23

The Continental XI-1430 Hyper engine (often identified as the IV-1430) was a liquid-cooled aircraft engine developed in the United States by a partnership between the US Army Air Corps and Continental Motors. It was the "official" result of the USAAC's hyper engine efforts that started in 1932, but never entered widespread production as it was not better than other available engines when it finally matured. In 1939, the I-1430-3 was designated as the engine to power the Curtiss XP-55, an extremely radical (for the time) pusher-engine fighter design that would not reach production.

In the late 1920s Harry Ricardo wrote a paper on the sleeve valve design that led to the USAAC's hyper engine efforts. He claimed that the 1 hp/in³ goal was impossible to achieve with poppet valve type engines. The USAAC engineering team at Wright Field decided to test this claim by beating it. The I-1430 was the result of an experimental effort at Wright Field to build a high-power cylinder using conventional poppet valves. The engineers, led by Sam Heron, used a variety of techniques to raise the allowable RPM, which was the key to increased power without requiring a larger engine.

The USAAC was interested in very large bomber designs, and in engines that could be buried in the wings in order to improve streamlining. From this requirement they designed a 12-cylinder horizontally opposed engine using twelve separate "hyper" cylinders. Although this sort of arrangement, with entirely separate cylinders from each other and the crankcase, was common for liquid-cooled Central Powers World War I-era inline-6 aviation engines, as in the German Mercedes D.III of nearly two decades earlier - and had been used for the 1918-era Allied Liberty L-12 liquid-cooled aviation engine with significant success - it had fallen from use in favor of engines featuring a monobloc engine design philosophy, with a cylinder block that combined the cylinders and the crankcase, leading to much stiffer engines, that were better able to handle increased power.

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