Heinemann treated every pound as the enemy. He deleted the wing-fold mechanism by making the wing small enough to fit carrier hangars as-is; he consolidated the avionics into a single package to save wiring and weight; he redesigned the ejection seat with roughly a third fewer parts; and he kept the structure and systems as simple as the mission allowed. The payoff was an attack jet that was cheap to build, easy to maintain, hard to break and delightful to fly.

The Navy’s specification had allowed 30,000 lb. The XA4D-1 prototype came in at an empty weight under 8,000 lb and a design gross weight far below the ceiling — while still meeting the range and payload the Navy demanded. It was one of the purest expressions of the idea that the best part is no part, and it defined a career that outlasted almost every contemporary.

Every other US Navy jet of its era folded its wings to fit the crowded carrier hangar deck. The Skyhawk did not. Heinemann sized the delta wing at about 27.5 ft span — small enough to strike below and park without any folding joint at all. Deleting that mechanism saved an estimated 200 lb of structure, hydraulics and maintenance, and removed a common source of failures. It became the aircraft’s signature trait and a neat symbol of the whole design: solve the problem by removing weight, not adding it.

Behind the modest “light attack” label, the A-4 was conceived as a carrier-based tactical nuclear delivery aircraft. Using the Low-Altitude Bombing System (LABS), a lone Skyhawk would sprint in at low level, pull up into a climbing arc and release its weapon so that it was “tossed” forward onto the target while the aircraft rolled and dived away to escape the blast. Early on it carried weapons such as the Mark 7 and Mark 12; later variants were cleared for the B43, B57 and B61. The mission shaped the airframe — small, fast at low level and long-legged for its size.

The A-4 was built in many variants over 25 years, so a single spec sheet never tells the whole story. Figures here are for the late A-4M Skyhawk II. Even for one variant, published maximum speeds range from about 645 to 688 mph and quoted bomb loads run from roughly 9,150 to 9,900 lb depending on the source and configuration — so treat those as ranges, not exact values. The A-4 was famously cheap for its day: early aircraft are commonly cited around $860,000, a fraction of the fighters around it. No reliable modern cost-per-flight-hour figure exists in open sources.