An attack helicopter is a type of military aircraft designed to provide close air support, air interdiction, and offensive aerial reconnaissance. The most commonly used attack helicopters are the APACHE, COBRA, ROTOR, and Blackhawk. The APACHE is a four-blade, twin-turboshaft attack helicopter manufactured by Boeing. The COBRA is a two-blade, single-engine attack helicopter manufactured by Bell Helicopter. The ROTOR is a five-blade, twin-engine attack helicopter manufactured by Kamov. The Blackhawk is a nine-blade, twin-engine attack helicopter manufactured by Sikorsky Aircraft.