Engineered to Deliver The Bomb, These Amazing Jets Delivered Alright
Development of the North American A3J (after 1962 the A-5) Vigilante began in 1953 as a privately-funded program to build a carrier-based supersonic bomber capable of filling the nuclear strike role for the United States Navy (USN). North American called the program the North American General Purpose Attack Weapon (NAGPAW). After engineering tweaks were incorporated into the design in 1955, the Navy’s Bureau of Aeronautics (BuAer) accepted the design. A contract for two prototypes followed in August of 1956, and North American chief test pilot Dick Wenzel flew the YA3J-1 for the first time almost exactly two years later.
Shocked and Awestruck
That’s how the Viggie got started. Nothing terribly surprising there. But the jet was nothing short of revolutionary for its time. The first production A3J-1 flew in 1960. Carrier qualification was completed aboard the carrier USS Saratoga (CVA-60) in 1960. When the A3J-1 became operational with Heavy Attack Squadron THREE (VAH-3) Sea Dragons at Naval Air Station (NAS) Sanford in Florida during June of 1961 it was the one of the largest, fastest, and most complex aircraft ever to be based aboard Navy aircraft carriers. Though only 156 of these awe-inspiring jets were produced, veterans of its era will never forget its combination of speed and power.
Power = Speed!
That power came from two General Electric J79-GE-8 afterburning turbojet engines- the very same power plants used in the McDonnell Douglas F-4 Phantom II and the Convair B-58 Hustler bomber among others. And the speed? Well the Viggie was easily capable of Mach 2 speeds at high altitudes (during a record-setting attempt the aircraft topped Mach 2.5) and supersonic speeds down low. McNamara’s 1962 Tri-Services Designation plan changed the bomber A3J-1 designator to A-5A, the bomber A3J-2 designator to A-5B, the bomber A3J-3 designator to A-5C, and the reconnaissance A3J-2P designator to RA-5C. Alphabet soup!
Firsts and Foremosts
The revolutionary aspects of the Vigilante included a number of firsts, including the first fly-by-wire control system (with mechanical backup) in a production jet, the computerized AN/ASB-12 attack/navigation system displayed on a head-up display (HUD) or Pilot’s Projected Display Indicator (PPDI) as it was called at the time, the multi-mode mono-pulse radar system with terrain-avoidance features, the radar-equipped inertial navigation system (REINS) which was based on similar tech used in North American’s SM-64 Navaho missile, the closed-circuit television camera under the jet’s nose, and the Versatile Digital Analyzer (VERDAN, a small digital computer) capable of integrating the “take” from the sensors.
Other features of the Viggie’s design that weren’t necessarily firsts included the small-area highly-loaded 37.5 degree swept wing equipped with boundary-layer control system (or blown) flaps without ailerons (spoilers/deflectors were used for roll control), the one-piece powered (all-moving) vertical and horizontal stabilizers, the variable engine inlets with both profile and area adjustments, the fully retractable refueling probe, the extensive use of titanium in the structure of the jet, the one-piece aluminum-lithium alloy wing skins, and even gold film and plating in the engine bays to reduce heat radiated through the structure.
The Vigilante also incorporated other new or emerging engineering such as an internal bomb bay (more about that later), a one-piece acrylic frameless windshield, and the use of inert nitrogen rather than flammable hydraulic fluid in hotter areas of the airframe. The jet was built with folding wings and vertical stabilizer as well as a nose radome that could be swung back along the side of the forward fuselage to decrease footprint aboard ship. The aircraft’s high-mounted swept wings and narrow-track landing gear, coupled with high approach speeds and angle of attack, could and sometimes did make for “interesting” carrier recoveries although the jet’s auto-throttle feature helped.
Train in the Tunnel
One unique aspect of the A-5 design was the linear bomb bay. Rather than release ordnance using conventional bomb bay doors in the aircraft’s underside, the Vigilante was designed to release “special” weapons from the aft fuselage horizontally between the two engines. Typically consisting of a Mark 28 thermonuclear bomb with a pair of attached fuel tanks, the payload was dubbed a “stores train.” Never (thankfully) used as designed, the internal bomb bay was instead used to carry additional fuel and occasionally mission electronics, especially in the RA-5C variants- although several times during cat shots the internal fuel tanks were left on the deck.