North American A-5 Vigilante

The North American A-5 Vigilante was an American carrier-based supersonic bomber designed for the United States Navy.

Prior to 1962 unification of Navy and Air Force designations, it was designated the A3J Vigilante.

The North American A-5 Vigilante was a supersonic carrier-based bomber.

At the time of its introduction, the Vigilante was one of the largest and by far the most complex aircraft to operate from an aircraft carrier.

It was furnished with a high-mounted swept wing with a boundary-layer control system (blown flaps) to improve low-speed lift. 

It lacked ailerons; instead, roll control was provided by spoilers in conjunction with differential deflection of the all-moving tail surfaces, which were paired with a relatively large all-moving single vertical stabilizer.

The use of aluminium-lithium alloy for wing skins and titanium for critical structures was also unusual for the era; other exotic materials included the use of a gold coating to reflect heat in key areas such as the bomb bay.

The wings, vertical stabilizer and the nose radome all folded to enable easier stowage onboard aircraft carriers.

Two widely spaced General Electric J79 turbojet engines were supplied with air through inlets with variable intake ramps.

While the same engine was used by several other US military aircraft, such as the Convair B-58 Hustler and the McDonnell Douglas F-4 Phantom II, the powerplants used on the A-5 differed in some ways, such as the use of a somewhat uncommon air-impingement starter along with a single igniter.

Both engines were equipped with constant-speed drives for alternators to generate a steady 30kVA for the onboard electrical systems, a hydraulically driven emergency supply generated by a ram air turbine was also installed.

The electronics of the Vigilante were relatively advanced and complex at the time of its entry to service.

It incorporated one of the first “fly-by-wire” systems on an operational aircraft, along with mechanical/hydraulic backup.

Other elements of its avionics include a computerized AN/ASB-12 nav/attack system incorporating a head-up display (“Pilot’s Projected Display Indicator” (PPDI), one of the first), multi-mode radar, radar-equipped inertial navigation system (REINS, based on technologies developed for North American’s Navaho missile), closed-circuit television camera under the nose, and an early digital computer known as “Versatile Digital Analyzer” (VERDAN) to operate it all.

According to Gunston and Gilchrist, the Vigilante was the first bomber to feature a digital computer. 

It was operated by a crew of two, a pilot and a bombardier-navigator (BN), that were seated in tandem; both were provided with North American HS-1A ejection seats.

On the reconnaissance-orientated aircraft; the bombardier-navigator was replaced by a reconnaissance/attack navigator (RAN) instead.

The single nuclear weapon, commonly the Mk 28 bomb, was attached to two disposable fuel tanks in the cylindrical bay in an assembly known as the “stores train”.

A set of extendable fins was attached to the aft end of the most rearward fuel tank.

These fuel tanks were to be emptied during the flight to the target and then jettisoned with the bomb by an explosive drogue gun.

The stores train was propelled rearward at about 50 feet (15 m) per second (30 knots) relative to the aircraft.

It then followed a ballistic path.

In practice, the system was not reliable, and no live weapons were ever carried in the linear bomb bay.

In the RA-5C configuration, the bay was used solely to accommodate fuel.

On three occasions, the shock of the catapult launch caused the fuel cans to eject onto the deck; this phenomenon reportedly resulted in one aircraft loss.

Early production Vigilante was outfitted with a pair of wing pylons, which were intended primarily for drop tanks.

The second Vigilante variant, the A3J-2 (A-5B), featured two additional wing hardpoints, for a total of four, and also incorporated internal tanks for an additional 460 gallons of fuel (which added a pronounced dorsal “hump”).

In practice, these hardpoints were rarely used.

Other improvements to the type included blown flaps on the leading edge of the wing and stronger landing gear.

While designated by the US Navy as a “heavy” aircraft, the A-5 was surprisingly agile; without the drag of bombs or missiles, even escorting fighters found that the clean airframe and powerful engines made the Vigilante very fast at high and low altitudes.

However, its high approach speed and high angle of attack contributed to a high workload during carrier landings.

Variants

XA3J-1

(NA247) Prototypes, two built, one converted to RA-5C, one crashed 1959.

A3J-1

58 built, 6 cancelled, survivors re-designated A-5A in 1962, 42 converted to RA-5C.

A3J-2

18 built, redesignated A-5B, 5 completed as XA3J-3P (YA-5C), all converted to RA-5C.

XA3J-3P

5 x A3J-2 completed from A3J-2 order without reconnaissance systems and assigned to pilot familiarization, later converted to RA-5C.

A3J-3P

20 built, re-designated RA-5C.

A-5A

A3J-1 re-designated.

A-5B

A3J-2 re-designated.

YA-5C

The 5 XA3J-3P aircraft re-designated, before conversion to RA-5C

RA-5C

Reconnaissance aircraft, 77 contracted, 8 cancelled, 69 built, plus 20 redesignated and 61 converted from earlier variants

NR-349

Proposed Improved Manned Interceptor for U.S. Air Force with three J79 engines and an armament of six AIM-54 Phoenix missiles.

Specifications

Crew

2

Length

76 ft 6 in (23.32 m)

Wingspan

53 ft 0 in (16.16 m)

Height

19 ft 5 in (5.91 m)

Wing area

701 sq ft (65.1 m2)

Empty weight

32,783 lb (14,870 kg)

Gross weight

47,631 lb (21,605 kg)

Max take-off weight

63,085 lb (28,615 kg)

Powerplant

2 × General Electric J79-GE-8 after-burning turbojet engines,

10,900 lbf (48 kN) thrust each dry, 17,000 lbf (76 kN) with afterburner

Performance

Maximum speed

1,149 kn (1,322 mph, 2,128 km/h) at 40,000 ft (12,000 m)

Maximum speed

Mach 2

Combat range

974 nmi (1,121 mi, 1,804 km) (to target and return)

Ferry range

1,571 nmi (1,808 mi, 2,909 km)

Service ceiling

52,100 ft (15,900 m)

Rate of climb

8,000 ft/min (41 m/s)

Wing loading

80.4 lb/sq ft (393 kg/m2)

Thrust/weight

0.72

Armament

Bombs

1× B27, B28 or B43 freefall nuclear bomb in internal weapons bay

2× B43, Mark 83,

Or

Mark 84 bombs on two external hard points

Avionics

Systems carried by A-5 or RA-5C

AN/ASB-12 Bombing & Navigation Radar (A-5, RA-5C)

Westinghouse AN/APD-7 SLAR (RA-5C)

Sanders AN/ALQ-100 E/F/G/H-Band Radar Jammer (RA-5C)

Sanders AN/ALQ-41 X-Band Radar Jammer (A-5, RA-5C)

AIL AN/ALQ-61 Radio/Radar/IR ECM Receiver (RA-5C)

Litton ALR-45 “COMPASS TIE” 2-18 GHz Radar Warning Receiver (RA-5C)

Magnavox AN/APR-27 SAM Radar Warning Receiver (RA-5C)

Itek AN/APR-25 S/X/C-Band Radar Detection and Homing Set (RA-5C)

Motorola AN/APR-18 Electronic Reconnaissance System (A-5, RA-5C)

AN/AAS-21 IR Reconnaissance Camera (RA-5C).