Continental XI-1430

File:Continental I-1430.jpg

I-1430-9 in National Museum of the USAF

The Continental XI-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 too small to be useful when it finally matured.

The original idea for the I-1430 started as an experimental effort at Wright Field to built a high-power cylinder using conventional poppet valves. In the late 1920s Harry Ricardo made the claim that poppet valve engines were a dead end, and the only way to make more powerful designs would be to use sleeve valves. The USAAC engineers were not so convinced, and started the "hyper engine" design in order to prove him wrong. The hyper used a variety of techniques to improve the allowable RPM, and thereby increase power without requiring a larger engine.

At the same time, the USAAC was interested in very large bomber designs, and were most interested 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 was common for World War I engines, it had fallen from use in favor of engines featuring a shared cylinder block, which led to much stiffer engines, better able to handle increased power. Looking for an industrial partner that could mass produce the design, they selected Continental and assigned it the O-1430 name ("O" for "opposed").

During development, interest in the "buried engine" concept faded. Improvements in conventional streamlining, notably the NACA cowling, eliminated the need for a buried engine for improved performance. Additionally, with bomber designs like the B-17 starting to enter production, the need for new bomber designs became less pressing and the Army turned its attention to new pursuit models. For this role the O-1430 was not terribly useful, so Continental modified the basic design into a V-12, and after learning of European models like the Junkers Jumo 210, into an inverted-V-12, the I-1430.

The I-1430 featured cylinders with "spherical" combustion chambers and sodium cooled exhaust valves. Although it retained the separate cylinders, the change to a V-layout allowed the cylinder tops to be connected together and then mounted at either end to a Y-shaped plate that provided stiffness. Continental built the first I-1430 engine in 1938 and successfully tested it in 1939. At the time it was an extremely competitive design, offering at least Template:Auto hp from a 23 liter displacement; the contemporary Rolls-Royce Merlin offered about Template:Auto hp from 27 l displacement, while the Daimler-Benz DB 601 offered slightly more power at Template:Auto hp, but was much larger, at 33 l displacement.

Had the I-1430 been able to enter production at that point it would have been a "winner", but for reasons that are not well recorded historically, the Hyper took a long time to mature. It was not until 1943 that the Template:Auto hp IV-1430 was tested extensively in the Lockheed XP-49, a modified version of the P-38 Lightning and was also to be used in the production version of the Bell XP-76. In 1944 it was also tested in the McDonnell XP-67. By this point in time interest in the design had largely disappeared; engines with the same power ratings were widely available, the Merlin had improved tremendously and was offering at least Template:Auto hp, and future developments were already starting to focus on jet engines.

Only twenty-three I-1430 series engines were delivered, later redesignated the XI-1430 to indicate the purely experimental use.

Specifications

• Model: Continental I-1430 Hyper
• Type: 12-cylinder, liquid-cooled, inverted Vee
• Displacement: 1,430 cu.in.
• Horsepower: 1,600
• RPM: 3,200
• Weight (dry): 1,615 lb.

References

• hyper engine
• http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=818
• Gunston, Bill (1986). World Encyclopedia of Aero Engines. Wellingborough: Patrick Stephens, 47-48. 
• White, Graham (1995). Allied Aircraft Piston Engines of World War II. Society of Automotive Engineers, Inc., P. 375-378. 
• Graham White's restored running IV-1430

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Continental XI-1430".