Complex sentence: In January 1965, McNamara asked the Air Force to consider a new low-cost tactical fighter design for short-range roles and close air support to replace several types like the F-100 Super Sabre and various light bombers then in service.
Split into simpler sentences: In January 1965, McNamara asked the Air Force to consider a new low-cost tactical fighter design for short-range roles and close air support. This would replace a collection of types like the F-100 Super Sabre and a variety of light bomber designs then in service.