The Wright R-2600 Cyclone 14 (also called Twin Cyclone) is an American radial engine developed by Curtiss-Wright and widely used in aircraft in the 1930s and 1940s. History In 1935, Curtiss-Wright began work on a more powerful version of their successful R-1820 Cyclone 9. The result was the R-2600 Twin Cyclone, with 14 cylinders arranged in two rows. The R-2600-3 was originally intended for the C-46 Commando (being fitted to the prototype CW-20A). It was also the original engine choice for the F6F Hellcat; a running change (one which would not stop production) for the CW-20A, and one in late April 1942 for the second XF6F-1, led to the adoption of the Pratt & Whitney R-2800 Double Wasp in the R-2600's place for both designs. The Twin Cyclone went on to power several important American World War II aircraft, including the A-20 Havoc, B-25 Mitchell, TBF Avenger, SB2C Helldiver, and the PBM Mariner. Over 50,000 R-2600s were built at plants in Paterson, New Jersey, and Cincinnati, Ohio. Variants R-2600-1 - 1,600 hp (1,194 kW) R-2600-2 - 1,500 hp (1,118 kW)- Prototype variant; Few were made. R-2600-3 - 1,600 hp (1,194 kW) R-2600-4 - 1,650 hp (1,230 kW) R-2600-6 - 1,600 hp (1,194 kW) R-2600-8 - 1,700 hp (1,268 kW) R-2600-9 - 1,700 hp (1,268 kW) R-2600-10 - 1,700 hp (1,268 kW)- Experimental high-altitude R-2600 variant with a two-stage mechanical supercharger, vs the usual single-stage supercharger. The 2600-10 also served as a testbed for turbo-supercharging the 2600 series. Very few were produced. R-2600-11 - 1,600 hp (1,194 kW) R-2600-12 - 1,700 hp (1,268 kW) R-2600-13 - 1,700 hp (1,268 kW) R-2600-14 - 1,700 hp (1,268 kW)- One of the engines which powered Grumman's prototype F6Fs, the XF6F-1 (the two-stage supercharged R-2600-10 was also tested in the XF6F-1). Grumman was not happy with the performance, which led to the 2,000 hp Pratt & Whitney R-2800 engine replacing the R-2600 on F6F production models. R-2600-15 - 1,800 hp (1,342 kW)- Planned to power the XB-33A, a prototype model of the B-33 Super Marauder (itself a high-altitude version of the B-26 Marauder). The project was cancelled, and neither the prototype XB-33A or production B-33A were ever built. R-2600-16 - 1,700 hp (1,268 kW)- Similar to the R-2600-10 & -14, the -16 powered a Grumman prototype F6F, the XF6F-2. R-2600-19 - 1,600 hp (1,194 kW), 1,660 hp (1,237 kW) R-2600-20 - 1,700 hp (1,268 kW),