The A-4 Skyhawk was designed by Douglas in response to a U.S. Navy call for a jet-powered attack aircraft to replace the older A-1 Skyraider. Douglas opted for a design that would minimize its size, weight, and complexity. The result was an aircraft that weighed only half of the Navy's weight specification. It had a wing so compact that it did not need to be folded for carrier stowage. A-4M: Dedicated Marine version with improved avionics and more powerful J52-P-408a engine with 11,200 lbf (50 kN) thrust, enlarged cockpit, IFF system. Later fitted with Hughes AN/ASB-19 Angle Rate Bombing System (ARBS) with TV and laser spot tracker, 158 built.