Early models of the A-4 Skyhawk came with two 20mm cannons. These systems were ultimately removed in later versions to cut down on weight and add space for more external ordnance. As for the A-4 ...

the American-made A-4 Skyhawk exemplified the U.S. Navy’s strike capabilities during the Vietnam War. The single-seat subsonic carrier-capable airframe entered service with the Navy Marine Corps ...

The A-4 Skyhawk was capable of carrying a bomb load ... the latter aircraft designated TA-4s with a two-seat cockpit. During the years 1974-1986, the A-4 also equipped the Blue Angels Navy Flight ...