Sleek Snooper

"Carried aboard mighty super carriers, the Navy’s Vigilante was supposed to take the fleets
heavyweight nuclear punch to sea - instead it became the task forces long-distance eyes."
by Jack Dean Airpower, March 2001 Volume 31

Editor's Note: Beginning in the mid-Fifties, and extending into the early Sixties, two different strike planes were developed for both the U. S. Navy and the Air Force. Similar in size and empty weight, the Navy's North American A-3/A-5 Vigilante, carrier-based attack bomber was the first to be completed, reaching the fleet in 1980. The Air Force's near counterpart, the General Dynamics F-111, began its flight test program four years later.

Although only 156 Vigilantes were completed (112 of were converted from earlier A3J bomber types) compared to more than 500 F-111s - 24 of which were delivered to the Royal Australian Air Force as F-111Cs - neither machine quite fulfilled the many expectations envisioned by their respective builders and operators, and the careers of both ended their service life as reconnaissance or electronic warfare aircraft.

But the similarities do not end there.

Even though the F-111 series of attack bombers/fighters had a pair of more powerful Pratt and Whitney TF330 engines, developing 11,500 lbs. of thrust each, compared to the Vigilante's two GE J79s with 10,800 lbs. of thrust. Their Mach 2-plus top speed was close, between 1375 and 1450 mph, with the F-111 holding the advantage. The Air Force bomber also had a higher mean altitude capability although, in 1960, the second Vigilante prototype climbed to an astounding 91,451 ft. with a 2,200 lb. payload, setting a world altitude record which no F-111 ever came close to equaling. Because it operated from standard ground bases, rather than limited size carrier decks, the F-111 also incorporated a much higher maximum take off weight, 100,000 lbs. vs. 80,000 lbs. for the Vigilante, but each was a bona tide supersonic strike aircraft, and the Vigilante had a slightly higher unrefueled endurance.

The similarities between the two, despite the Vigilante having been designed 4 to 5 years earlier were startlingly significant. Both had an empty weight of between 40,000 and 46,000 lbs., much of that difference do to the F-111's variable wing-sweep geometry plumbing, and the fact that in order to operate from carrier decks, the Vigilante was forced to adhere to a more rigid weight-saving regimen. Both utilized a similar shoulder wing configuration, although the F-111 was much narrower and longer (75 ft. span vs. the Vigilante's 53 ft. ) so that the two resembled each other only when viewed from the front and side, Fuselage length was again similar: 76 ft. for the A-3/A-5, compared to 73 ft. for the F-111. The only significant dimensional difference between them was in area, where the broad-winged Vigilante had a surface of 753 sq. ft. to the F-111's 525 sq. ft.

Although each aircraft was certainly different, both resulted In a similar payoff. The Navy soon found that the Vigilante was too limited for its attack/recon role, particularly considering its size aboard ship - where space is at a premium - and its relatively small payload; and when it finally left the fleet in 1979, early RA-5C recon models had been in storage for nearly five years. By that time, Grumman's two-seat, all-weather F-14 Tomcat was already well into its service and it weighed nearly the same as a fully loaded Vigilante.

Somewhere between the development of the Vigilante and. the F-111, and their full deployment, the armed services had begun to dramatically alter their thinking concerning attack weapons systems, downsizing not only the numbers to be purchased but also their size. The large, powerful F-14 Tomcat was to be thee Navy’s last outsized weapons carrier. Its replacement would be McDonnell's dual purpose F-18 Hornet, which grossed out at fully seven tons less. In the Air Force, after the F-111 was removed as an active bomber in 1991, with only some special EF-111 electronic jamming models remaining in service, future planning began to concentrate on lighter weight attack weapons. Although the McDonnell F-15 Eagle air superiority strike fighter remained in roughly the same weight category as its Navy F-14 counterpart (66,000 lbs. maximum for take off), the USAF relied much more on its so-called lightweight counterpart, the General Dynamics (now Lockheed) F-16 fighter for the attack mission, loading that minimal-dimensioned interceptor to a gross weight of 38,000 lbs., most of it represented by up to nine tons of ordnance and fuel, making the aircraft its principal tactical fighter or attack plane. And future developments continue in the same vein.

At the time the Vigilante and the F-111 made their service debuts, many of these multiple capabilities also could be realized, but only through the incorporation of a number of costly and complex systems, which raised overall weight and were, in fact, overly complicated by today's standards. Nevertheless, when compared to what had gone before, their level of sophistication and performance was truly miraculous, especially when one considers that ten year's prior to the initial design of the Vigilante, the Navy's latest best attack plane, the Douglas A-1 Skyraider, had yet to fly. In remembering the Vigilante and its USAF counterpart the F-111, the reader should not lose sight of the tremendous strides made in the development of combat aircraft within a decade of World War II's end. In fact, these very real accomplishments have only been eclipsed in the last few. ' years by aircraft that do the same thing, but do it more reliably, more effortlessly, and within a much smaller context of overall size that is also much easier to service and maintain.

A one-piece, all-flying tail; variable geometry engine inlets, adjustable for optimum performance at a desired speed, complete with ramps. fore and aft, to control airflow; a bird strike-resistant windshield of stretched acrylics; a wing leading edge extension or LEX; computerized fly-by-wire controls, with mechanical backup; an airborne digital computer - the first in any aircraft - for navigation and bombing, coupled with an inertial auto-navigation system with television sighting for visually determining exact position at all times terrain avoidance radar; fully integrated autopilot and air data system for weapons release; a heads-up display; slot deflector spoilers for roll control; the use of aluminum lithium alloy in airframe construction, with special gold plate in the engine bays to reflect heat.

Sounds like features currently being incorporated into the new Lockheed F-22 Raptor air superiority fighter? Maybe, but they were all found on the Navy's North American A-3/A-5 Vigilante all-weather attack plane, a design begun nearly fifty years ago.

In addition to the exotic systems enumerated above, the nearly thirty five ton, catapult-launched Vigilante also featured a swept wing with blown flaps, which used compressed air to increase lift, coupling these with a leading edge flap or droop section that enhanced handling at lower speeds. Instead of ailerons, roll control was accomplished by a three-section series of spoilers and deflectors on each side. The two inboard spoilers deflected air- flow upward, the outboard spoiler, mounted inverted, pushing it down-ward. The aircraft was designed with a minimal radar cross-section and, within its tong, sleek fuselage, it carried a four-megaton Mk 28 hydrogen bomb, the Navy's answer to the Air Force's nuclear weapons monopoly. This eight ft. long, 1,980 lb. store was located in an internal tubular bay which contained up to 2,400 lbs, of titanium, situated between the Vigilante's two 10,800 lb. thrust GE J79 engines which, with afterburning, could deliver up to 17,900 lbs. of thrust each. In a unique method of delivery, the bomb was activated by a solid fuel cartridge catapult system connected to a pair of jettisonable fuel tanks, the entire assembly mounted on rails. An explosive charge blew off the aircraft's tail cone and released the bomb behind the conformal fuel tanks, a in train, the tanks acting as stabilizers on the bomb's trajectory to its target.

Developed as the North American General Purpose Attack Weapon (NAG- PAW) in 1953 at the company's Columbus, Ohio division under the auspices of Chief Engineer, George Gehrkens, with Frank Conipton in charge of weapons systems and Mac Blair heading up airframe design, what came to be the A3J Vigilante was a company funded project and an unsolicited proposal. It wasn’t until 1955 that the Navy negotiated a contract for a pair of two-seat, high altitude, Mach 2, nuclear-carrying penetration prototypes that became the A3J and later the A-5.

Ever since the development of the atomic bomb, the Navy had fought a losing battle with the Air Force to achieve some parity in nuclear capability. Despite the development of the 55,000 lb. AJ Savage, beginning in 1946, which had a limited service life as a carrier- based bomber, followed by the all-jet and much heavier (82,000 lbs.) Douglas A-3 Skywarrior of 1949, which did not fly until October, 1952, it was clear that the USAF still held tight to its overwhelming control of America's nuclear arsenal.

Designed to be carried aboard bigger carriers like the Kennedy, the A-3 Vigilante served on Kennedy, Ranger, Saratoga, Independence, America, Constellation, Kitty Hawk, Forrestal and the nuclear carrier Enterprise. In most instances it was then known as the A-5 or RA-5, a change in designation that occurred in 1962, when a new tri-service identification system eliminated the traditional naval manufacturer's coding in favor of a plain A for Attack or F for Fighter. Since the Navy already had an A-3 bomber from Douglas, the Vigilante became the A-5, before again being designate RA-5 when it incorporated the reconnaissance mission

When based aboard ship, a Vigilante compliment was usually a dozen aircraft, and the first operational unit was assigned to VAH-7, aboard the Enterprise. But, although it was sleek, fast and long-ranging, with an unrefueled range of nearly 3,000 miles, the A-3/A-5 had its shortcomings. One was a relatively low combat load. North American engineers remedied this somewhat by deleting the blown flaps system and increasing the wing's chord and span to improve range, adding wing fillets for improved low-speed handling, deepening the fuselage to allow for larger fuel tanks, and raising the fuselage's roofline behind the cockpit for installation of an extra tank over the wing center section, thereby making available another 500 gallons of internal fuel. They also doubled the under-wing pylons to four. In the process they developed a photo-reconnaissance model, the RA-5C, which carried cameras, side-looking radar, infrared sensors and electronic countermeasures (ECM) equipment in a long canoe faring attached beneath the ventral fuselage.

With these changes and upgraded engines, Vigilantes could easily fly a 2,000 mile mission and return. The new bomber also caused redesign of the elevators aboard the newer carriers, making them longer, and the moving of the carrier's island further abaft of amidships. Despite folding wingtips, it canoe fairing attached beneath the it also required a hangar height of at least 25 ft., and the aircraft's higher energy jet fuels dictated changes in the ships capacity and increased storage space. Moreover the catapult power also had to he upgraded. With each now carrier equipped with four, they had to have an upper limit launch weight of 65,000 lbs. at 150 knots during the length of their 250-ft. stroke. For recovery, the ship would require at least 17 knots over the deck to land the Vigilante at a weight of no more than 42,000 lbs., with a run of 60 ft. to the forward wire from touchdown point, and a run-out of 350 ft, plus 100 ft. to turn off.

Tailoring the Vigilante to these stringent requirements was as difficult as tailoring its carriers to meet the challenge of basing the new attack/recon bomber, the heaviest aircraft to ever regularly serve aboard ship. These numerous and mandatory modifications and adjustments were to take their toll. First flown in May of 1958, arriving at the fleet two years later, when it made its first carrier landing aboard the USS Saratoga in July, 1960, becoming fully operational in squadron service in January, 1962, the Vigilante program was already in trouble.

The beginning of full-scale production did not commence until 1959 and although the new bomber seemed completely at home aboard ship, it had a problem. Despite all the novel features it had introduced, apart from reaching Mach 2.02 and an altitude of 91,000-plus ft. in 1960, the aircraft's payload was still not particularly impressive. Moreover, bomb drops of the free-fall nuclear weapon, while attached to a pair of empty fuel cells for stabilization, did not function as advertised - one reason why the sleek fuselage, where all weapons and fuel were to be carried internally to permit higher speeds, was augmented by four under wing pylons and a ventral electronics camera/sensor canoe.

By the summer of 1962 it was apparent that the newly redesignated A-5 was not going to be a cost-effective Is attack threat. The Navy was already switching to and concentrating on submarines to carry its nuclear weapons, and even though the A-5 could haul a variety of missiles, among them the Martin Bullpup B with its 1,000 lb. warhead, so could ordinary carrier fighters, and they were much cheaper to procure. Furthermore, in optimizing it for nuclear weapons carriage, with speed and range predominate, the Vigilante designers had downplayed conventional weapons capacity. In July of 1962, the first RA-5C made its maiden flight and it was obvious that, even before the first nuclear attack Vigilantes had been certified, the Navy was already prepping the aircraft for a new mission. After building two prototype A-5s, followed by nine more service test machines and sixty six production models, North American delivered the next seventy nine as RA-5 reconnaissance ships, while converting forty three more from standard A-5 types.

In a conventional attack mode - not counting 8,000 lbs, of internal bomb bay capability - the Vigilante could have carried two 1,000 lb. bombs on inboard pylons, plus twelve 500 lb. bombs on multiple ejector racks outboard, or twelve 500 lb. weapons outboard, along with two 400 gallon external fuel tanks, inboard, giving it a combat radius of 1,500 miles at a standard cruise of 500 mph a 900 mph. approach speed, a dash over the target area of 1200 mph and a maximum escape speed of 1300 mph. With the sixth production A-5 already completed out of 42 ordered, the Navy switched the remaining thirty six to an improved RA-5 reconnaissance configuration and, by the fall at 1963, four of these were already being utilized as trainers for the new mission which extended combat radius to 2,000 miles and allowed the aircraft to cruise to its approach point at 600 mph. These examples were followed by forty-three RA-5Cs and, by 1967, with the war in Vietnam providing a combat backdrop, the Vigilante was beginning to prove its worth.

With its radar, electronics, sensors and cameras installed in an eight station ventral canoe, the camera exposures lit by a strobe light battery mounted inboard under its wing on either side, the RA-5C began obtaining excellent photographic coverage of North Vietnamese targets, both pre- and post-strike. But with eighteen Vigilantes lost, the Navy restarted the production line, producing thirty-six additional aircraft for a grand total of 156, the last Vigilante leaving the Columbus line in August. 1970.

Not counting development work and spares, the Vigilante cost the Navy nine million per aircraft; with development funding added. the cost rose to seventeen million, approximately four times that of a contemporary F-4 Phantom heavy fighter, or about half the cost of today's F-16. Unlike its predecessors the last thirty six featured a hood-like leading edge extension or LEX, running from the wing's root to the tip of the forward air intake. Previously, the wing's leading edge had connected to the fuselage aft of the intake.

Of the eighteen aircraft lost in Vietnam, eleven succumbed to heavy antiaircraft fire, two fell to SAM surface-to-air missiles, and an air-to-air missile fired by a MiG 21 interceptor shot down one.

Combat flying the Vigilante was a pleasurable experience, considering the aircraft's power and speed. Over land, the RA-5 always flew at supersonic speeds, at altitudes usually under 10,000 ft. Once it had taken its pictures or effectively jammed enemy radar, it was difficult for escorting U. S. fighters to keep up with it, as they rapidly burned up fuel. Because of its speed, the Vigilante was invariably the last plane to launch from the carrier, easily making up the distance on its mission escorts.

Most photographs were taken from 8,000 ft., where all types of enemy anti-aircraft weapons from 20mm to 120mm could reach the camera-toting intruder. As a consequence, the Vigilante crew had to rely on the aircraft's blistering speed and, with their oblique-looking cameras, did not have to fly directly over a target to photograph it. The Vigilante's maneuverability, for such a large aircraft, also helped it in evading SAM missiles, Stability was another of its virtues, particularly when landing back aboard ship at a rather high 165 mph. (The early A3J models stall speed was a prohibitive 200 mph. It was later reduced to 165 mph.) On-center arrested landings demanded a near perfect lineup with the carrier's deck, particularly critical in a large, heavy aircraft with the Vigilante's wingspan, and precise approach techniques had to he followed to the letter, given the Vigilante's streamlined shape which was difficult to slow down, the pilot adhering to a specific rate of descent.

Launching was also an exhilarating experience, the RA-5 requiring maxi-mum steam power on the deck catapults. With its twin J79s in afterburner, the acceleration slammed you hack into the seat and the radar navigation officer in the second seat had to brace himself securely with his hands on the plotting shelf directly in front of him or on the ejection handles above his head. Once aloft, however, the ride was smooth and comfortable, both cockpit stations being large and roomy.

During the Vietnam War, five squadrons of some 60 aircraft deployed to Southeast Asia, with one remaining in Florida as a training unit and another serving with the Sixth Fleet in the Mediterranean, Early in the conflict, a squadron would have up to six of its aircraft ready for the day's missions, and these could be ordered at any time throughout a 24-hour period; but as the war progressed, and losses cut deeply into the number of available machines the ready figure was whittled down to just three by 1974, with one aircraft serving as a parts department for the others.

At the beginning of this article we briefly discussed some of the many systems incorporated into the Vigilante, several of them making an appearance for the first time in a combat aircraft. But what did they actually do?

In the case of the radar-equipped inertial navigation system, with its digital computer analyzer, the system allowed the radar officer to tie into the autopilot, and by programming coordinates from a map into the computer, he could initially take the plane to any one of six different locations. The navigator could also reprogram for additional destinations while in flight, at any time, and although he could not change speed cases, the rendezvous with the tanker would usually take to 30 degrees. The Vigilante also had a first rate terrain avoidance capability, which worked down to a minimum of 100 ft., steering it between mountains and along valley floors automatically, but the ride was bruising and tremendously uncomfortable.

These systems were extremely sophisticated for the late Fifties, much of them supplied by North American's own Autonetics Division, and took up to six months to learn operationally. They not only performed well, hot also did so regardless of the Vigilante's speed, no matter how many course changes were made, or if they were ordered simultaneously. With a clean configuration and so much fuel in just as effectively and much more economically. But the mark tanks - Vigilante crews enjoyed. relatively long loiter times, particularly over their own carriers, watching other aircraft burdened by external stores seeking priorities far immediate landing.

Even with its internal fuel capacity, many Vigilante missions over Vietnam required in-flight refueling, in order to fly over distant, well-defended targets at high. speed. In those cases rendezvous with the tanker would usually take place at 35,000 ft. and off the coast, before the Vigilante turned hack to cross over its target areas at 8,000 ft. On some of these clashes the big aircraft would routinely and easily reach speeds of better than 1,000 mph., and as it did, it sent its photos hack to the carrier's interpretation center automatically, in real time

Developed to carry the Navy’s nuclear punch to sea, the Vigilante was an amazingly fast airframe stocked with a wealth of electronic marvels, but it was too big for the attack mission, demanding more deck and hangar space aboard ship than could he easily provided. During its service tenure it was realized that smaller aircraft could deliver its offensive wallop just as effectively and much more economically. But, the mark of a successful combat aircraft is its ability to take on a completely new mission, without major alteration. This the RA-5 Vigilante did with aplomb.