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Alun_D
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aeronewsline :: Accueil :: Histoire :: Aéronefs 1956 à 1965
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Re: North American A-5 Vigilante
par Alun_D Lun 13 Sep 2010, 09:19
The Vigilante had extremely advanced and complex electronics when it first entered service.
It had one of the first fly-by-wire systems of an operational aircraft (with mechanical/hydraulic backup) and 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 the Navaho missile), closed-circuit television camera under the nose, and an early digital computer known as VERDAN (Versatile Digital Analyzer) to run it all.
It had one of the first fly-by-wire systems of an operational aircraft (with mechanical/hydraulic backup) and 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 the Navaho missile), closed-circuit television camera under the nose, and an early digital computer known as VERDAN (Versatile Digital Analyzer) to run it all.
Alun_D- CLUB
- Messages : 2003
Re: North American A-5 Vigilante
par Alun_D Lun 13 Sep 2010, 09:21
Given its original design as a carrier-based nuclear heavy attack aircraft, the Vigilante's main armament was carried in a novel "linear bomb bay" between the engines in the rear fuselage, which was intended to make bomb delivery safer for the flight crew and more accurate.
When conventional bombers "drop" a bomb, the bomb falls downward, but continues forward at the same speed as the aircraft.
When conventional bombers "drop" a bomb, the bomb falls downward, but continues forward at the same speed as the aircraft.
Alun_D- CLUB
- Messages : 2003
Re: North American A-5 Vigilante
par Alun_D Lun 13 Sep 2010, 09:23
This requires pilot and navigator/bombardier skill and complicated equipment to place a bomb on its intended target.
The linear bomb bay would eject the payload rearward at approximately the same speed as the forward velocity of the aircraft, causing the bomb to "stand still" and drop straight down. No calculation is needed - the bomb falls at the point at which it was dropped.
As an added benefit, the aircraft is rapidly moving away from the dropped bomb, enabling lower drop altitudes or safer drops from higher altitudes.
The linear bomb bay would eject the payload rearward at approximately the same speed as the forward velocity of the aircraft, causing the bomb to "stand still" and drop straight down. No calculation is needed - the bomb falls at the point at which it was dropped.
As an added benefit, the aircraft is rapidly moving away from the dropped bomb, enabling lower drop altitudes or safer drops from higher altitudes.
Alun_D- CLUB
- Messages : 2003
Re: North American A-5 Vigilante
par Alun_D Lun 13 Sep 2010, 09:24
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".
The idea was for the fuel tanks to be emptied during flight to the target and then jettisoned as part of the bomb by an explosive drogue gun. In practice the system was never reliable and no live weapons were ever carried in the linear bomb bay. In the RA-5C configuration, the bay was used solely for fuel.
On three occasions the shock of the catapult launch caused the fuel cans to eject onto the deck resulting in one aircraft loss.
The idea was for the fuel tanks to be emptied during flight to the target and then jettisoned as part of the bomb by an explosive drogue gun. In practice the system was never reliable and no live weapons were ever carried in the linear bomb bay. In the RA-5C configuration, the bay was used solely for fuel.
On three occasions the shock of the catapult launch caused the fuel cans to eject onto the deck resulting in one aircraft loss.
Alun_D- CLUB
- Messages : 2003
Re: North American A-5 Vigilante
par Alun_D Lun 13 Sep 2010, 09:26
The Vigilante originally had two wing pylons, intended primarily for drop tanks.
The second Vigilante variant, the A3J-2 (A-5B), incorporated internal tanks for an additional 460 gallons of fuel (which added a pronounced dorsal "hump") along with two additional wing hardpoints, for a total of four.
In practice the hardpoints were rarely used.
Other improvements included blown flaps on the leading edge of the wing and sturdier landing gear.
The second Vigilante variant, the A3J-2 (A-5B), incorporated internal tanks for an additional 460 gallons of fuel (which added a pronounced dorsal "hump") along with two additional wing hardpoints, for a total of four.
In practice the hardpoints were rarely used.
Other improvements included blown flaps on the leading edge of the wing and sturdier landing gear.
Alun_D- CLUB
- Messages : 2003
Re: North American A-5 Vigilante
par Alun_D Lun 13 Sep 2010, 09:30
The reconnaissance version of the Vigilante, the RA-5C, had slightly greater wing area and added a long canoe-shaped fairing under the fuselage for a multi-sensor reconnaissance pack.
This added an APD-7 side-looking airborne radar (SLAR), AAS-21 infrared linescanner, and camera packs, as well as improved ECM. An AN/ALQ-61 electronic intelligence system could also be carried.
This added an APD-7 side-looking airborne radar (SLAR), AAS-21 infrared linescanner, and camera packs, as well as improved ECM. An AN/ALQ-61 electronic intelligence system could also be carried.
Alun_D- CLUB
- Messages : 2003
Re: North American A-5 Vigilante
par Alun_D Lun 13 Sep 2010, 09:32
The RA-5C retained the AN/ASB-12 bombing system, and could, in theory, carry weapons, although it never did in service.
Later-build RA-5Cs had more powerful -10 engines with afterburning thrust of 17,900 lbf (80 kN).
The reconnaissance Vigilante weighed almost five tons more than the strike version with almost the same thrust and an only modestly enlarged wing.
These changes cost it acceleration and climb rate, though it remained fast in level flight.
Later-build RA-5Cs had more powerful -10 engines with afterburning thrust of 17,900 lbf (80 kN).
The reconnaissance Vigilante weighed almost five tons more than the strike version with almost the same thrust and an only modestly enlarged wing.
These changes cost it acceleration and climb rate, though it remained fast in level flight.
Alun_D- CLUB
- Messages : 2003
Re: North American A-5 Vigilante
par Alun_D Lun 13 Sep 2010, 09:35
Operational history
Designated A3J-1, the Vigilante first entered squadron service with Heavy Attack Squadron THREE (VAH-3) in June 1961 at Naval Air Station Sanford, Florida, replacing the A-3 Skywarrior in the heavy attack role.
All variants of the Vigilante were built at North American Aviation's facility at Port Columbus Airport in Columbus, Ohio, alongside the T-2 Buckeye and OV-10 Bronco.
Designated A3J-1, the Vigilante first entered squadron service with Heavy Attack Squadron THREE (VAH-3) in June 1961 at Naval Air Station Sanford, Florida, replacing the A-3 Skywarrior in the heavy attack role.
All variants of the Vigilante were built at North American Aviation's facility at Port Columbus Airport in Columbus, Ohio, alongside the T-2 Buckeye and OV-10 Bronco.
Alun_D- CLUB
- Messages : 2003
Re: North American A-5 Vigilante
par Alun_D Lun 13 Sep 2010, 09:37
Under the Tri-Services Designation plan implemented under Robert McNamara in September 1962, the Vigilante was redesignated A-5, with the initial A3J-1 becoming A-5A and the updated A3J-2 becoming A-5B.
The subsequent reconnaissance version, originally A3J-3P, became the RA-5C.
The subsequent reconnaissance version, originally A3J-3P, became the RA-5C.
Alun_D- CLUB
- Messages : 2003
Re: North American A-5 Vigilante
par Alun_D Lun 13 Sep 2010, 09:57
The Vigilante's early service proved troublesome, with many teething problems for its advanced systems.
Although these systems were highly sophisticated, the technology of the time was in its infancy, and its reliability was poor. In early squadron service, the MTBF (Mean Time Between Failures) for some systems was sometimes as short as 15 minutes.
Although these systems were highly sophisticated, the technology of the time was in its infancy, and its reliability was poor. In early squadron service, the MTBF (Mean Time Between Failures) for some systems was sometimes as short as 15 minutes.
Alun_D- CLUB
- Messages : 2003
Re: North American A-5 Vigilante
par Alun_D Lun 13 Sep 2010, 09:58
Although most of these reliability issues were eventually worked out as maintenance personnel gained greater experience with supporting these systems, the aircraft tended to remain a maintenance-intensive platform throughout its career.
Alun_D- CLUB
- Messages : 2003
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