The A-5 Vigilante is an American aircraft from the 1950s and ’60s that stands out for its excellent performance and technological advances, but also for its complexity and cost.
Equipped with two massively powerful engines, titanium panels, one of the first digital computers in an aircraft and gold-plated engine housings, this was a bird that spared no expense.
But did the A-5 Vigilante prove to be worth the cost? Well, not really.
A Fast Nuclear Bomber is Needed
The first musings for what would become the A-5 started in the first half of the 1950s. World War Two had kick started a massive technological boom, particularly with aircraft, that only increased with the end of the war.
The jet engine and advances in aerodynamics had transformed military aircraft, and engineers were continuing to see what they could do with these new toys.
The end of the war left US aircraft manufacturers scrambling to make the most of these changes and establish themselves amongst the intense competition. It was a time of great opportunity, but it also great risk; technology was evolving so fast that new designs could quickly be made obsolete.
In 1953, North American Aviation (NAA) – the company behind the P-51 Mustang – privately began investigating the possibility of a supersonic, long-range nuclear strike bomber that could be launched from aircraft carriers.
This was right up the US Navy’s street, as they desperately wanted their own method of long-range nuclear weapons delivery. At this time they were using the AJ Savage for this role, but this twin piston engine bomber was simply outdated by the 1950s.
NAA’s proposal was known internally as the North American General Purpose Attack Weapon, or the NAGPAW. This was eventually changed to NA-233.
It was two have two engines, a top speed of Mach 2, and carry heavy bomb loads, all while operating from carriers. To achieve this it would need highly advanced avionics and flight surfaces, exotic materials, large fuel storage and powerful engines – it was certainly ambitious!
After the basic concept had been established, NAA presented the NA-233 to the US Navy. They were impressed and interested, but actually declined a number of features suggested by NAA, such as twin tailfins to reduce the height of the aircraft inside a carrier. This is a standard feature on modern combat aircraft.
NAA also looked into fitting the NA-233 with a rocket booster; this would be used over enemy territory during nuclear attack runs, making it harder to intercept and allowing the aircraft to get further away from the blast.
The Navy rejected this as it didn’t want to handle the fuel required for such a system.
NAA incorporated the requested changes into the aircraft, and had a prototype ready by May 1958. It was given the designation YA3J-1, which would change to A-5 Vigilante in 1962.
A-5 Vigilante Description
NAA’s Vigilante was an incredibly advanced aircraft for its day, and contained a literal list of firsts or recently developed technologies.
It had a very modern shape, with twin fuselage-mounted engines at the rear, air inlets either side of the forward fuselage, and a high-mounted swept wing.
Crew totalled two: one pilot, and one back-seater bombardier/navigator.
It was also a very large aircraft, especially for a carrier-based design, measuring 76 ft 6 in (23.3 meters) in length (longer than a B-17) and possessing a wing span of 53 ft (16 meters). At maximum load the Vigilante weighed 63,000 lbs (28,600 kg).
The A-5 Vigilante was a big and heavy machine that had to be stored in, and operate from the small space of a carrier and then reach speeds of Mach 2.
As such, weight was kept down via the use of strong, but light materials like aluminium-lithium alloy and titanium.
Its high-speed design naturally limited its low-speed handling, so its ailerons were replaced by very large flaps that generated more lift at low speeds. The Vigilante relied on its tailplane surfaces and wing spoilers for roll-movement in flight.
This was further assisted by air that was bled from the engines and blown over the wings.
Internally, the Vigilant was one of the most complex aircraft ever made.
It was one of the first aircraft to contain a solid state digital computer, which in the A-5 was the Versatile Digital Analyzer, or VERDAN. This cutting-edge computer ran the aircraft’s many systems.
It was also one of the first aircraft to feature a fly-by-wire system (a decade before the first commercial airliner did the same). This was paired with a mechanical backup in case of failures.
But the Vigilante’s most impressive feature is often regarded as its AN/ASB-12 Bomb Directing Set. A multi-mode radar in the nose would relay its data to the pilot via one of the first heads-up displays, known as the Pilot’s Projected Display Indicator, or PPDI.
A television camera fitted under the nose was used as a bombsite, and could also be projected onto the pilot’s PPDI or bombardier/navigator’s display.
At the rear of the aircraft were two widely-spaced J-79 afterburning turbojets, the same basic engine that powered other famously fast aircraft like the B-58 Hustler and F-4 Phantom.
These engines provided the Vigilante with 34,000 lbf of thrust with afterburners, but created considerable heat built up. This was mitigated by gold-plating on the inside of the engine nacelles.
The Vigilante was also one of the first aircraft to have variable engine inlets, which reduced incoming supersonic air to subsonic speeds, allowing the engines to remain efficient at any speed.
All of this produced a top speed of just under 1,400 mph. Remember that just over a decade prior, 400 mph was considered fast!
It was such a fast aircraft that heat-build up on the airframe was a real issue. North American addressed this with titanium panels and nitrogen rather than hydraulic fluids in the areas that got the hottest.
Other features included ejection seats, a retractable in-flight refuelling probe and folding wing tips for carrier storage.
However one of the most interesting parts of the A-5 Vigilante’s design is where it carried its ordnance.
The A-5 in its basic form did not carry weapons externally, nor did it have a typical bomb bay. Instead, it stored its bombs inside a “linear bomb bay”, which is essentially a long tube located between the engines.
The payload contained within the tube was ejected from the rear of the aircraft through an opening between the engines, rather than being released below. This theoretically has a number of advantages.
It eliminates the need for heavy bomb bay doors. These doors would also add significant drag during bombing runs, when the aircraft should be travelling fast.
The Vigilante’s Expensive Service
The A-5 Vigilante took its first flight on August 31, 1958, from Columbus, Ohio. Less than a year later though, one prototype was lost after a system failure on board the aircraft.
In 1960 the aircraft (still known as the A3J-1) was used on a number of record-setting flights to help the project gain popularity. During one such flight, a Vigilante accelerated to just past Mach 2 and then began a vertical climb all the way to 91,000 ft.
The Navy accepted the Vigilante into service in 1961, but by this time the aircraft’s original purpose as nuclear strike aircraft was fading away. The Navy had invested heavily into submarine-launched nuclear ballistic missile technology, which achieved the task of delivering nuclear weapons faster, more accurately and were much, much harder to counter.
In addition, the A-5 Vigilante proved to be a maintenance hog – a consequence of containing so many cutting-edge but unproven systems.
Its novel bomb bay was of particular note here, as while on paper it looked promising, in reality it was a failure. The A-5 never carried nuclear weapons when deployed, so the bay was only used for additional fuel stores.
Read More The Beautiful PBY Catalina in 26 Images
When jettisoning the bay’s contents, they would sometimes become caught in the aircraft’s turbulence, totally ruining their accuracy.
And on a few occasions, the jolt of the carrier’s launch catapult knocked the fuel cannisters out of the rear while still on the deck. Just imagine the “oh no” feeling watching a nuclear bomb rolling aimlessly across the deck, had it been armed with one.
Without its original purpose and unreliable combat performance, the Navy shifted the A-5 into a reconnaissance role. This variant was designated RA-5C, and incorporated many new features that better optimised the aircraft for this job.
The RA-5C carried a much greater fuel load, evidenced by a distinct “hump” along the top of the fuselage.
Underneath, the RA-5C carried a large suite of highly advanced reconnaissance equipment. It had side, forward and straight down-looking cameras, infrared sensors to detect heat signatures and a side-looking radar.
It also carried an “electronic intelligence (ELINT)” system that detected radar emissions and calculated their exact position by their frequencies and patterns.
The A-5 may have had a lacklustre career, but its flight characteristics cannot be denied. It was known to be an extremely fast aircraft with a high service ceiling, rate of climb, and, considering its size, good manoeuvrability.
It held its altitude record for over a decade, and was able to hang with many fighters in terms of performance, especially at higher altitudes.
There was briefly a proposal to create an interceptor version of the A-5 Vigilante for the programme that sought to replace the F-106, named the NR-349. This would have been fitted with three J-79s, with the third located where the bomb bay used to be.
This aircraft was not developed as in the end the US settled on keeping the F-106.
By the 1970s the A-5 was coming to the end of its usefulness. Its reconnaissance role could be achieved much more easily and less costly by other serving aircraft like the F-4 Phantom and F-8 Crusader, and its size was becoming a hindrance on carriers.
The introduction of the F-14 Tomcat, and budget cuts after the Vietnam War resulted in the A-5 Vigilante being retired from service in the late 1970s. In total, 167 examples of all variants were built.