The result was the R-2600 Twin Cyclone, with 14 cylinders arranged in two rows. The 1,600 hp (1,200 kW; 1,600 PS) R-2600-3 was originally intended for the C-46 Commando (being fitted to the prototype CW-20A) and 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 2,000 hp (1,500 kW; 2,000 PS) Pratt & Whitney R-2800 in its place for both designs. The Twin Cyclone went on to power several important American-designed World War II aircraft, including the A-20 Havoc, B-25 Mitchell, TBF Avenger, SB2C Helldiver, and PBM Mariner.