Hope this is a good cockpit image (even if it is a model one)
The rapid evolution of aircraft design in the 1950s led to new aircraft types with sleek lines and impressive performance. One such aircraft was the North American A-5/RA-5 "Vigilante". The Vigilante was designed as a carrier-based strategic nuclear bomber, but would see action over Vietnam as a fast reconnaissance aircraft.
[1] ORIGINS / A3J-1 (A-5A)
* In the postwar period, the US Navy was determined to obtain a nuclear strike capability, first acquiring the North American AJ "Savage" and Douglas A-3 "Skywarrior" bombers. These were both subsonic aircraft, and since aircraft design was evolving quickly at the time, both soon became obsolete for the missions for which they had originally been designed.
North American Aviation (NAA) felt they could provide a more capable nuclear strike platform, and in November 1953 the company's Columbus, Ohio, division began a program on their own initiative using company funding to build such an advanced carrier-based nuclear-strike bomber. The development team was led by Frank G. Compton.
The new aircraft was originally referred to as the "North American General Purpose Attack Weapon (NAGPAW)" and later given the company designation of "NA-233". After discussions with the Navy, the NAA-233 concept took shape as a twin-engine aircraft with advanced combat avionics, Mach 2 performance, and an interesting "linear bomb bay" in which a nuclear weapon was popped out the tail to give the aircraft a better chance of escaping the atomic blast. North American engineers also considered fitting the aircraft with an auxiliary rocket engine powered by jet fuel and hydrogen peroxide for an additional burst of speed over the target area, but the Navy didn't like the idea of handling a nasty, toxic, reactive, and unstable substance like hydrogen peroxide on board a ship, and so it didn't happen.
* The Navy gave North American the go-ahead for two prototypes in mid-1956. The first prototype of the "YA3J-1 Vigilante", as it was formally designated, was rolled out on 16 May 1958. Initial flight was on 31 August 1958, with North American chief test pilot Dick Wenzel at the controls.
The Vigilante was long and sleek, with a relatively small high-mounted swept-back wing, and all-moving slab tailplanes and tailfin. The aircraft had tricycle landing gear, with the main gear retracting into the fuselage. All three gear had single wheels and retracted forward, with the main gear rotating 90 degrees during retraction to fit into the wheel wells. The Vigilante was powered by twin General Electric YJ79-GE-2 engines, with engine bays made mostly of titanium, and covered with gold film to reflect heat. The aircraft had a large fuel capacity to give it long range and permit extended flight in afterburner.
The aircraft achieved good low-speed landing performance through the use of large flaps. The ailerons were eliminated to make room for the flaps, with roll control provided by differential movement of the tailplanes and an innovative scheme of spoilers. There were three spoilers on each wing, just forward of the rear flight control surfaces; there were actually spoilers on each surface of the wing, with a spoiler on one surface hinged at the front matched to a spoiler on the other hinged at the rear. When a spoiler was deployed, it formed a "vent" of sorts through the wing. The two topside inboard spoilers were hinged at the front, while the topside outboard spoiler was hinged at the rear. A "boundary layer control (BLC)" scheme was incorporated, in which air bled from the engines was automatically blown over the flaps when they were extended, in order to lower landing speed.
The wingtips folded up for carrier hangar storage. North American had considered twin tailfins to meet the height restrictions of a carrier hangar deck, but although such a configuration is common now, it was too bold for the Navy at the time. North American went with a single tall tailfin that folded to one side.
The Vigilante featured a long list of new technologies, including wing skins made of aluminum-lithium alloy; critical structures made of titanium; variable ramp engine inlets; a windshield of stretched acrylics; and a retractable mid-air refueling probe. The two crewmen flew in tandem cockpits with individual "clamshell" canopies, sitting in North American HS-1 rocket-boosted ejection seats. The pilot could control ejection for both crewmen, though the back-seater could also eject on his own if necessary.
While the pilot had a good forward view, the "bombardier-navigator" in the back seat had only a small window to each side. Originally, North American engineers hadn't intended to provide any windows for the back-seater on the assumption that he would be able to see his displays better in the dark and would be protected from nuclear flash, but feedback on the idea from prospective bombardier-navigators was very negative. The engineers added the two little windows as a concession.
The Vigilante had the advanced North American Autonetics "AN/ASB-12 Bomb Directing Set", which included:
A multi-mode radar. The nose radome had a power mechanism to allow it to pivot upward, not only for service access but to reduce the aircraft's "footprint" when stowed in a carrier hanger. The radar unit itself pivoted downward for service when the nose was lifted.
A radar computer with an associated "Pilot's Projected Display Indicator (PPDI)" one of the first "head-up displays" to be fitted to an operational aircraft.
A TV camera under the nose for daylight target sighting, with the imagery passed to the pilot's PPDI and the back-seater's radar display.
A "Radar-Equipped Inertial Navigation System (REINS)", based on technologies developed for the unsuccessful Navaho intercontinental cruise missile.
A digital computer system designated the "Versatile Digital Analyzer (VERDAN)" -- which some jokers claimed actually stood for "Very Effective Replacement for a Dumb-Ass Navigator". It was one of the first solid-state computer systems ever fitted to an aircraft.
The Vigilante was also one of the first aircraft to have a "fly by wire" electric flight control system.
* The second prototype flew in November 1958. The flight test program went well, though the second prototype was lost on 3 June 1959 when its hydraulic and electrical systems failed. The crew presumably survived, sources not mentioning any fatalities associated with the accident.
The first production "A3J-1" Vigilante flew in 1960. Production aircraft were progressively fitted with more powerful J79 engine variants, leading to J79-GE-8 engines, with 48.5 kN (4,945 kgp / 10,900 lbf) dry thrust and 75.6 kN (7,710 kgp / 17,000 lbf) afterburning thrust. These were the same engines used on many of the Navy's McDonnell Douglas F4H-1 (F-4B) Phantom fighter, simplifying logistics and maintenance.
Carrier trials began in July 1960. To promote the Vigilante with the US Congress, the Navy also established several speed and altitude records with the aircraft. On 13 December 1960, Navy test pilots Commander Leroy Heath and Lieutenant Larry Monroe took their Vigilante to Mach 2.1 and then nosed it up into a climb that brought it to a record 27,750 meters (91,000 feet). At that altitude, the aircraft was no longer aerodynamic and tumbled onto its back as it fell down the far side of the arc, with the engines flaming out in the thin atmosphere. However, such problems had been encountered in practice flights leading up to the attempt and the flight crew knew what to expect. Heath simply neutralized the controls; once the Vigilante reached thicker air halfway through its fall, it naturally adopted a nose-down attitude, and Heath was able to relight the engines.
Deliveries of the A3J-1 to operational units began in 1961, with last deliveries of the type in 1963. By that time it had been redesignated the "A-5A", due to a Defense Department decision to come up with a common designation scheme for all US military aircraft, implemented in September 1962.
Carrier air group commanders were not entirely pleased with the Vigilante. Although the aircraft had excellent performance and the airframe proved reliable, it was full of "bleeding edge" electronic technologies and was a maintenance headache. During the testing phase, the VERDAN computer had a "mean time between failure (MTBF)" of 15 minutes! However, within a few years the computer's MTBF was up to a reasonable 240 hours.
The Vigilante was also something of a handful to land on a carrier, since it was not only big but also very sleek and "hot". On a hard landing, the aircraft would "bounce", with the nosewheel tire popping and tearing apart on the second strike to shed pieces of rubber into the engines. In addition, the nosewheel strut proved weak and had to be reinforced. Some Vigilante pilots claimed that the aircraft's reputation for being difficult to land was exaggerated, but did admit that it was unforgiving. The aircraft acquired a reputation as something of a beast that required particular skill to fly, and of course Vigilante pilots were not quick to disagree. Egos were involved, which could be big and antagonistic in the male-oriented, hyper-competitive Navy Air culture.
Fighter pilots of course tended to look down on the big bomber, comparing it to an elephant, though apparently at least as much for the wild sounds made by the Vigilante's twin J79s when they were throttled up or down during landing approach, with jokers suggesting that the beast sounded like it was in heat. Leroy Heath, back in normal fleet service, picked up the comparison and ran with it, naming his Vigilante the PASSIONATE PACHYDERM. He also bought a wind-up toy elephant, painted the PACHYDERM's aircraft number "701" on its side, and took to setting it on strolls across the closed-circuit TV camera that gave the pilot ready rooms a view of carrier-deck landings.
One A-5A pilot, Lieutenant Commander Ken Enney, decided to fight back more aggressively by "bouncing" a Vought Crusader fighter. The fighter pilot eventually called out over radio: "I can't get rid of this guy!" This set off quite a buzz among the flight crews, though Enney himself later admitted that his Vigilante was lightly loaded and that he could only have gotten away with such a stunt at altitudes above 6,000 meters (20,000 feet).
* By this time the last A-5As were delivered to the fleet, there was no interest in using the Vigilante for nuclear strike, or even conventional attack. Partly the issue was political, partly it was technical.
The political issue was that the Navy's Polaris submarines were coming on line, and the Navy decided to focus on Polaris as the service's strategic nuclear strike weapon. The Vigilante development program cost about $200 million USD in contemporary dollars, with the pricetag of each aircraft rising to about $10 million USD, and the Navy felt that their other existing strike aircraft, such as the new Grumman Intruder, were more cost-effective for conventional strike missions.The technical issue was that the Vigilante wasn't looking very promising in the strike role anyway. The linear bomb bay scheme sounded nice on paper, but it was a nightmare in practice. The bomb bay tube ran up the fuselage between the engines, and since it was much longer the nuclear store, expendable fuel tanks were tacked on in the rear of the store. During a strike, the entire assembly was popped out the tail with an explosive cartridge driving it down launch rails. Not only did the scheme prove unreliable, the store also tended to "draft" behind the aircraft, preventing the pilot from laying it down accurately. The linear bomb bay would never actually be used for weapons delivery in practice.
The Vigilante, in short, had become an expensive aircraft without a clear mission. However, instead of simply dumping it, the US Navy decided that the Vigilante should be used for a different mission, the fast reconnaissance role.
The decision to develop the Vigilante strictly as a reconnaissance aircraft was taken at a time when efforts were already being made to enhance its attack abilities, as well as adapt it to the reconnaissance mission. An improved attack variant, the "A3J-2" (later "A-5B"), and a reconnaissance version, the "RA-5C", were both built.
Work began on the A-5B in 1961, with the first example flying at the end of April 1962. The most visible change from the A-5A was a modified "humpback" fuselage that offered a substantial increase in fuel capacity. Longer and wider flaps were fitted, as well as a new BLC scheme, in which high-pressure engine bleed was fed to the front of the wing instead of the back. Four stores pylons were fitted, two under each wing, each with a load capability of up to 950 kilograms (2,000 pounds). The engine inlet ducts were also modified, and the brakes were improved to handle the increase in aircraft weight.
18 A-5Bs were ordered, but by the time the first of them was flying the Navy had given up on the Vigilante as a bomber. Only six A-5Bs were completed. They were used in an interim training role for the reconnaissance version, the RA-5C, and never reached fleet service. The remaining twelve machines in the batch were completed as RA-5Cs.
* The RA-5C was developed in parallel with the A-5B, and first flew on 30 June 1962. The RA-5C incorporated all the new features of the A-5B, such as the humpback fuselage, the big flaps, and the leading-edge BLC system. The new BLC scheme proved a little tricky, since it required more engine power. Since the RA-5C was substantially heavier than the A-5A, this meant that once the BLC system was engaged the aircraft lost power and tended to drop abruptly.
The tunnel-store system was retained, and in fact it appears that the RA-5C was still capable of carrying the old primary store train and could also be fitted with the four stores pylons. In practice, however, the RA-5C was never armed.
The major difference from the A-5B was the RA-5C's equipment fit, which featured a suite of reconnaissance gear that was state-of-the-art for the time. The TV camera under the nose became part of the reconnaissance suite, but most of the gear was carried in a long slender "canoe" on the bottom of the aircraft's fuselage and running from the nose gear back towards the tail. The reconnaissance suite consisted of the following sensor systems, listed from front to rear:
KA-51A/B forward-looking oblique angle film camera.
KA-50A, KA-51A, or KA-62A vertical film camera.
Passive electronics countermeasures (PECM) antenna for the AN/ALQ-61 Electronic Reconnaissance System. The AN/ALQ-61 was an "electronic intelligence (ELINT)" system that would pick up radar emissions and pin down their coordinates, frequency, and pulse pattern. The ELINT data was recorded on magnetic tape, with storage capacity for 112 minutes of continuous ELINT observations.
Various combinations of panoramic, vertical, or oblique film cameras. Camera fit included KA-58A panoramic camera for medium- to high-altitude work, or a KA-57A panoramic camera for low-altitude work. The cameras shot through prisms in the canoe that could be pivoted to permit shots straight down or from side to side.
AN/AAS-21 infrared sensor, which could provide a continuous film strip of thermal targets, such as hidden trucks, over a field of view 140 degrees wide.
Antenna for the Westinghouse AN/APD-7 "side looking airborne radar (SLAR)" system, which shot radar pulses out to the side of the aircraft and stored the return echo on a long film strip, permitting all-weather, day-night imaging.
Another PECM antenna for the AN/ALQ-21 system.
An electronic strobe flash pod, powered by a spinner on its tail, could be carried under one wing to provide illumination for night reconnaissance. The sensor systems on the RA-5C worked in conjunction to bring back a flood of information from a reconnaissance mission, stored on magnetic tape and photographic film.
Specifications (A-5A Vigilante)
General characteristics
Crew: 2
Length: 76 ft 6 in (23.32 m)
Wingspan: 53 ft 0 in (16.16 m)
Height: 19 ft 4¾ in (5.91 m)
Wing area: 700 ft² (65.1 m²)
Empty weight: 32,714 lb (14,870 kg)
Loaded weight: 47,530 lb (21,605 kg)
Max. takeoff weight: 62,953 lb (28,615 kg)
Powerplant: 2 × General Electric J79-GE-8 afterburning turbojets
Dry thrust: 10,900 lbf[17] (48 kN) each
Thrust with afterburner: 17,000 lbf[17] (76 kN) each
Performance
Maximum speed: Mach 2.0 (1,149 knots, 1,320 mph, 2,123 km/h) at 40,000 ft (12,200 m)
Combat radius: 1,121 nmi[dubious – discuss] (1,289 mi, 2,075 km)
Ferry range: 1,571 nmi (1,807 mi, 2,909 km)
Service ceiling: 52,100 ft (15,880 m)
Rate of climb: 8,000 ft/min (40.6 m/s)
Wing loading: 80.4 lb/ft² (308.3 kg/m²)
Thrust/weight: 0.72
Armament
Bombs:
1× Mark 27 nuclear bomb, B28 or B43 freefall nuclear bomb in internal weapons bay
2× B43, Mark 83, or Mark 84 bombs on two external hardpoints
Avionics
Systems carried by A-5 or RA-5C[18][19]
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)
We need a jet bomber, this is a good one, a nuclear bomber, and is not too advanced.
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Topic: North American RA-5 Vigilante (Read 9029 times)
