Wright Cyclone series

Wright Cyclone was the name given to a family of air-cooled radial piston engines designed by Curtiss-Wright and used in numerous American aircraft in the 1930s and 1940s.

Background

The Wright Aeronautical Corporation was formed in 1919, initially to develop Hispano-Suiza engines under licence. The Corporation’s first indigenous design, the R1, was also the first successful high-powered radial in the USA. Funded by contracts from the US Navy for new air-cooled radials, Wright started a new design (initially called the P2) in 1924. The resignation of Frederick B. Rentschler to join Pratt & Whitney, along with several key engineering personnel, seriously affected the development of the P2 and it did not go into production.

Cyclone family

• Wright R-1300 Cyclone 7
• Wright R-1820 Cyclone 9
• Wright R-2600 Cyclone 14 (Twin Cyclone)
• Wright R-3350 Cyclone 18 (Duplex Cyclone)
• Wright R-4090 Cyclone 22

R-1750 Cyclone 9

A new design was launched in 1926, known as the R-1750 Cyclone. This was a nine-cylinder radial with a displacement of 1750 cu in and internally cooled exhaust valves. It was type-tested at 500 hp in 1927.

R-1820 Cyclone 9

Wright merged with Curtiss in 1929 and recovered from the loss of Rentschler and other engineering staff. In 1932, the R-1750 was developed to a capacity of 1823 cu in. This was the F model Cyclone, designated R-1820. This engine introduced a forged aluminium crankcase and was developed through the 1930s to reach 890 hp. It used a bought-in General Electric supercharger and Wright concluded that this feature limited the potential power output of the engine. For the next development, the G-Series of 1937, Wright developed its own single-speed supercharger. The G-series was developed to deliver 1200 hp at 2500 rpm and made up the bulk of R-1820 Cyclone production during World War 2. The final phase of development of the single row radial design was the H-Series at 1350 hp.

R-2600 Cyclone 14

Wright went on to develop two-row engines with 14 cylinders in two rows of 7, called the Cyclone 14, R-2600. This was installed in the Boeing 314, Grumman TBM/TBF Avenger, North American B-25 Mitchell, and some models of the Douglas A-20 Havoc (RAF Boston).

R-3350 Cyclone 18

The final Cyclone development was the 18 cylinder engine R-3350, called the Duplex Cyclone or Cyclone 18. Among other applications, it was installed in Douglas A-1 Skyraider, Lockheed P-2 Neptune, and Lockheed C-121 Constellation, but the most crucial military application for this engine was the B-29 bomber, whose most memorable exploits were the to carry the atomic bomb to Hiroshima and Nagasaki. In other commercial applications it stayed in production until 1957.

R-4090 Cyclone 22

Based on the mechanical components of the R-2600 and R-3350, the Cyclone 22 was a two-row 22 cylinder development intended to compete directly with the Pratt & Whitney R-4360 engine, but was not proceeded with.

See also

• Pratt & Whitney Wasp - a comparable competing line of engines