The CH-47 Chinook is a twin-engine, tandem rotor, heavy lift helicopter. A true workhorse that was designed and produced in the early 1960s, this aircraft is the Army's only heavy-lift cargo helicopter. Recent changes to a "Block II" configuration include a more efficient drivetrain, new swept-tip rotor blades, and a strengthened fuselage that allows for heavier payloads. Six fuel tanks are reduced to two, allowing the Block II to carry more fuel while losing weight.