As a result, piston-engined fighters, such as the F8F Bearcat, an aircraft from the Grumman stable with one of the most powerful piston engines ever developed for a single-engined aircraft, the Pratt & Whitney P&W R-2800 radial engine, would be used to combat the insurgents. With this powerful engine (2100 hp), the Bearcat was probably the fastest propeller-driven aircraft with a maximum speed of over 450 mph. (The Americans would follow their lead in their war against the Việt Minh by using the Douglas A-1 Skyraider piston-engined aircraft during the 1960s.) For the task of dropping large "hardware" on guerrilla groups, the twin-engined bomber Douglas B-26 Invader would also be chosen. A revised command structure for the "Armée de l'Air" in Indochina was also put in effect with the creation of three "Groupes aériens tacticques" (Gatac) ("Aerial Tactical Groups"): Gatac North in Hanoi, Gatac Center in Hué and Gatac South in Saigon/Tan Son Nhut.