Grumman A-6 Intruder

The Grumman A-6 Intruder is an American twinjet all-weather attack aircraft developed and manufactured by American aircraft company Grumman Aerospace that was operated by the U.S. Navy.

A-6 Intruder
KA-6D Intruder of Attack Squadron 34 (VA-34 "Blue Blasters")
Role Attack aircraft
National origin United States
Manufacturer Grumman
First flight 19 April 1960
Introduction 1963
Retired 28 April 1993 (USMC)
28 February 1997 (USN)
Primary users United States Navy
United States Marine Corps
Produced 1962–1992
Number built 693
Developed into Northrop Grumman EA-6B Prowler

The A-6 was developed during the late 1950s and early 1960s in response to a requirement issued by the United States Navy for an all-weather jet-powered carrier-based attack aircraft. It was designed as a successor for multiple existing medium-sized attack aircraft, such as the piston-engined Douglas A-1 Skyraider. Unlike its predecessors, and even some contemporaries, the A-6 made extensive use of interconnected avionics. Operated by a crew of two in a side-by-side seating configuration, the workload was divided between the pilot and weapons officer (bombardier/navigator (BN)). In addition to conventional munitions, the type was also compatible with the Navy's air-based nuclear weapons, which were deploy-able via toss bombing techniques. On 19 April 1960, the prototype performed the type's maiden flight.

The A-6 was in service with the United States Navy and Marine Corps between 1963 and 1997, multiple variants of the type being introduced during this time. From the A-6, a specialized electronic warfare derivative, the EA-6B Prowler, was developed as well as a KA-6D which was used as a tanker.[1] It was deployed during various overseas conflicts, including the Vietnam War and the Gulf War. The A-6 was intended to be superseded by the McDonnell Douglas A-12 Avenger II, but this program was ultimately canceled due to cost overruns. Thus, when the A-6E was scheduled for retirement, its precision strike mission was initially taken over by the Grumman F-14 Tomcat equipped with a LANTIRN pod.

Development

Background

Following the good performance of the propeller-driven Skyraider in the Korean War, the United States Navy issued preliminary requirements in 1955 for an all-weather carrier-based attack aircraft. The U.S. Navy published an operational requirement document for it in October 1956. It released a request for proposals (RFP) in February 1957.[2] This request called for a 'close air support attack bomber capable of hitting the enemy at any time'. Aviation authors Bill Gunston and Peter Gilchrist observe that this specification was shaped by the service's Korean War experiences, during which air support had been frequently unavailable unless fair weather conditions were present.[3]

In response to the RFP, a total of eleven design proposals were submitted by eight different companies, including Bell, Boeing, Douglas, Grumman, Lockheed, Martin, North American, and Vought.[4] Grumman's submission was internally designated as the Type G-128.[3] Following evaluation of the bids, the U.S. Navy announced the selection of Grumman on 2 January 1958. The company was awarded a contract for the development of their submission, which had been re-designated A2F-1, in February 1958.[5]

YA2F-1 showing the original tilting tailpipes

Grumman's design team was led by Robert Nafis and Lawrence Mead, Jr.[3] Mead later played a lead role in the design of the Lunar Excursion Module and the Grumman F-14 Tomcat.[6] The team was spread between two sites, the company's manufacturing plant as Bethpage and the testing facilities at Naval Weapons Industrial Reserve Plant, Calverton. During September 1959, the design was approved by the Mock-Up Review Board.[3]

The A2F-1 design incorporated several cutting-edge features for the era. In the early 1960s, it was novel for a fighter-sized aircraft to have sophisticated avionics that used multiple computers. This design experience was taken into consideration by NASA in their November 1962 decision to choose Grumman over other companies like General Dynamics-Convair (the F-111 had computerized avionics capabilities comparable to the A-6, but did not fly until 1964) to build the Lunar Excursion Module, which was a small-sized spacecraft with two onboard computers.

Into flight

The first prototype YA2F-1, lacking radar and the navigational and attack avionics, made the Intruder's first flight on 19 April 1960,[7][8] with the second prototype flying on 28 July 1960.[9] In general, flight testing experiences of the prototypes were positive.[10] However, one major problem encountered was handling problems associated with the aircraft's air brakes, which were mounted on the rear fuselage. In an attempt to solve this, the third prototype had its horizontal tailplane moved rearwards by 16 inches (41 cm), but this did not completely solve the handling problems. Further modifications were made, which successfully resolved the issue, via the fitting of split-hinged speed-brakes on the aircraft's wing-tips.[9]

Early production aircraft were fitted with both the fuselage and wingtip air brakes, although the fuselage-mounted items were soon bolted shut, and were removed from later aircraft.[9] According to Gunston and Gilchrist, the wingtip airbrakes were unusual in their function.[11] Another major difference between the prototypes and production aircraft was present in the design of the jet nozzles; as originally designed, the nozzles were intended to swivel to a downwards position, facilitating shorter takeoffs and landings. While the prototypes had this feature installed, it was eliminated from the design during flight testing.

Further development

During February 1963, the A-6 was introduced to service with the US Navy; at this point, the type was, according to Gunston and Gilchrist, "the first genuinely all-weather attack bomber in history".[11] However, early operating experiences found the aircraft to be imposing very high maintenance demands, particularly in the Asian theatre of operations, and serviceability figures were also low. In response, the Naval Avionics Lab launched a substantial and lengthy program to improve both the reliability and performance of the A-6's avionics suite.[11] The successful performance of the A-6 in operations following these improvements ended proposals to produce follow-on models that featured downgraded avionics.[12]

Various specialized variants of the A-6 were developed, often in response to urgent military requirements raised during the Vietnam War.[13] The A-6C, a dedicated interdictor, was one such model, as was the KA-6D, a buddy store-equipped aerial refuelling tanker. Perhaps the most complex variant was the EA-6B Prowler, a specialized electronic warfare derivative. The last variant to be produced was the A-6E, first introduced in 1972; it features extensive avionics improvements, including the new APQ-148 multimode radar, along with minor airframe refinements.[13] The last A-6E was delivered in 1992.[14]

During the 1980s, a further model, designated A-6F, was being planned. Intended to feature the General Electric F404 turbofan engine, as well as various avionics and airframe improvements, this variant was cancelled under the presumption that the in-development McDonnell Douglas A-12 Avenger II would be entering production before long.[15][16] Instead, a life-extension program involving the re-winging of existing A-6E aircraft was undertaken; initially a metal wing had been used before a graphite-epoxy composite wing was developed during the late 1980s.[17] Other improvements were introduced to the fleet around this time, including GPS receivers, new computers and radar sets, more efficient J-52-409 engines, as well as increased compatibility with various additional missiles.[18]

Design

The Grumman A-6 Intruder is a two-seat twin-engined monoplane, equipped to perform carrier-based attack missions regardless of prevailing weather or light conditions.[3] The cockpit used an unusual double pane windscreen and side-by-side seating arrangement in which the pilot sat in the left seat, while the bombardier/navigator (BN) sat to the right and slightly below. In addition to a radar display for the BN, a unique instrumentation feature for the pilot was a cathode ray tube screen that was known as the Vertical Display Indicator (VDI). This display provided a synthetic representation of the world in front of the aircraft, along with steering cues provided by the BN, enabling head-down navigation and attack at night and in all weather conditions.[19]

The A-6's wing was relatively efficient at subsonic speeds, particularly when compared to supersonic fighters such as the McDonnell Douglas F-4 Phantom II, which are also limited to subsonic speeds when carrying a payload of bombs. The wing was also designed to provide a favorable level of maneuverability even while carrying a sizable bomb load. A very similar wing would be put on pivots on Grumman's later supersonic swing-wing Grumman F-14 Tomcat, as well as similar landing gear.[20] The Intruder was also equipped with the "Deceleron", a type of airbrake on the wings with two panels that opened in opposite directions; in this case, one panel went up, while another went down.

For its day, the Intruder had sophisticated avionics, with a high degree of integration.[3] To aid in identifying and isolating equipment malfunctions, the aircraft was provided with automatic diagnostic systems, some of the earliest computer-based analytic equipment developed for aircraft. These were known as Basic Automated Checkout Equipment, or BACE (pronounced "base"). There were two levels, known as "Line BACE" to identify specific malfunctioning systems in the aircraft, while in the hangar or on the flight line; and "Shop BACE", to exercise and analyze individual malfunctioning systems in the maintenance shop. This equipment was manufactured by Litton Industries. Together, the BACE systems greatly reduced the Maintenance Man-Hours per Flight Hour, a key index of the cost and effort needed to keep military aircraft operating.

The Intruder was equipped to carry and launch nuclear weapons (B43, B57, B61) and Navy crews regularly planned for assigned nuclear missions. Because the A-6 was a low-flying attack aircraft, a semi-automated toss bombing method was developed. Known as LABS-IP (Low Altitude Bombing System – Initial Point) it called for a high-speed low-level approach. Nearing the target point, the pilot would put the aircraft into a steep climb. At a computer-calculated point in the climb, the weapon would be released, with momentum carrying it upwards and forwards. The pilot would continue the climb even more steeply, until near a vertical position the aircraft would be rolled and turned, heading back in the direction from which it came. It would then depart from the area at maximum acceleration. During this time, the bomb would rise to an apex, still heading in its original direction, then begin to fall towards the target while traveling further forward. At a pre-programmed height, it would detonate. By that time, the Intruder would be several miles away, traveling at top speed, and thus able to stay ahead of the shock wave from the explosion. This unusual maneuver was known as an "over the shoulder" bomb launch.

Operational history

Entering service and Vietnam War
An A-6E Intruder aircraft assigned to USS Dwight D. Eisenhower.
S-3A Viking, A-6E Intruder, and an EA-6B Prowler aircraft are parked on the flight deck of aircraft carrier USS John F. Kennedy during a storm.

The Intruder received a new standardized US DOD designation of A-6A in the Autumn of 1962, and entered squadron service in February 1963. The A-6 became both the U.S. Navy's and U.S. Marine Corps's principal medium and all-weather/night attack aircraft from the mid-1960s through the 1990s and as an aerial tanker either in the dedicated KA-6D version or by use of a buddy store (D-704). Whereas the A-6 fulfilled the USN and USMC all-weather ground-attack/strike mission role, this mission in the USAF was served by the Republic F-105 Thunderchief and later the F-111, the latter which also saw its earlier F-111A variants converted to a radar jammer as the EF-111 Raven, analogous to the USN and USMC EA-6B Prowler.

A-6 Intruders first saw action during the Vietnam War, where the craft were used extensively against targets in Vietnam. The aircraft's long range and heavy payload (18,000 pounds or 8,200 kilograms) coupled with its ability to fly in all weather made it invaluable during the war. However, its typical mission profile of flying low to deliver its payload made it especially vulnerable to anti-aircraft fire, and in the eight years the Intruder was used during the Vietnam War, the U.S. Navy and U.S. Marine Corps lost a total of 84 A-6 aircraft of various series. The first loss occurred on 14 July 1965 when an Intruder from VA-75 operating from USS Independence, flown by LT Donald Boecker and LT Donald Eaton, commenced a dive on a target near Laos. An explosion under the starboard wing damaged the starboard engine, causing the aircraft to catch fire and the hydraulics to fail. Seconds later the port engine failed, the controls froze, and the two crewmen ejected. Both crewmen survived.

A U.S. Marine Corps A-6 Intruder destroyed by a rocket and mortar bombardment on Da Nang Air Base in 1968 during the Vietnam War

Of the 84 Intruders lost to all causes during the war, ten were shot down by surface-to-air missiles (SAMs), two were shot down by MiGs, 16 were lost to operational causes, and 56 were lost to conventional ground fire and AAA. The last Intruder to be lost during the war was from VA-35, flown by LT C. M. Graf and LT S. H. Hatfield, operating from USS America; they were shot down by ground fire on 24 January 1973 while providing close air support. The airmen ejected and were rescued by a Navy helicopter. Twenty U.S. Navy aircraft carriers rotated through the waters of Southeast Asia, providing air strikes, from the early 1960s through the early 1970s. Nine of those carriers lost A-6 Intruders: USS Constellation lost 11, USS Ranger lost eight, USS Coral Sea lost six, USS Midway lost two, USS Independence lost four, USS Kitty Hawk lost 14, USS Saratoga lost three, USS Enterprise lost eight, and USS America lost two.[21] Although capable of embarking aboard aircraft carriers, most U.S. Marine Corps A-6 Intruders were shore based in South Vietnam at Chu Lai and Da Nang and in Nam Phong, Thailand.

Lebanon and later action

A-6 Intruders were later used in support of other operations, such as the Multinational Force in Lebanon in 1983. On 4 December, one LTV A-7 Corsair II and one Intruder were downed by Syrian missiles. The Intruder's pilot, Lieutenant Mark Lange, and bombardier/navigator Lieutenant Robert "Bobby" Goodman ejected immediately before the crash;[22] Lange died of his injuries while Goodman was captured and taken by the Syrians to Damascus where he was released on 3 January 1984. Later in the 1980s, two Naval Reserve A-7 Corsair II light attack squadrons, VA-205 and VA-304, were reconstituted as medium attack squadrons with the A-6E at NAS Atlanta, Georgia and NAS Alameda, California, respectively.

Intruders also saw action in April 1986 operating from the aircraft carriers USS America and Coral Sea during the bombing of Libya (Operation El Dorado Canyon). The squadrons involved were VA-34 "Blue Blasters" (from USS America) and VA-55 "Warhorses" (from USS Coral Sea).

An A-6E Intruder prepares for launch aboard USS Enterprise

During the Gulf War in 1991, U.S. Navy and U.S. Marine Corps A-6s flew more than 4,700 combat sorties, providing close air support, destroying enemy air defenses, attacking Iraqi naval units, and hitting strategic targets. They were also the U.S. Navy's primary strike platform for delivering laser-guided bombs.[23] The U.S. Navy operated them from the aircraft carriers USS Saratoga, USS John F. Kennedy, USS Midway, USS Ranger, USS America and USS Theodore Roosevelt, while U.S. Marine Corps A-6s operated ashore, primarily from Shaikh Isa Air Base in Bahrain. Three A-6s were shot down in combat by SAMs and AAA.[24]

The Intruder's large blunt nose and slender tail inspired a number of nicknames, including "Double Ugly", "The Mighty Alpha Six", "Iron Tadpole" and also "Drumstick".[25]

Following the Gulf War, Intruders were used to patrol the no-fly zone in Iraq and provided air support for U.S. Marines during Operation Restore Hope in Somalia. The last A-6E Intruder left U.S. Marine Corps service on 28 April 1993.[26]

Navy A-6s saw further duty over Bosnia in 1994.

Retirement

Despite the production of new airframes in the 164XXX Bureau Number (BuNo) series just before and after the Gulf War, augmented by a rewinging program of older airframes, the A-6E and KA-6D were quickly phased out of service in the mid-1990s in a U.S. Navy cost-cutting move driven by the Office of the Secretary of Defense to reduce the number of different type/model/series (T/M/S) of aircraft in carrier air wings and U.S. Marine aircraft groups.

The A-6 was intended to be replaced by the McDonnell Douglas A-12 Avenger II, but that program was canceled due to cost overruns.[27] The Intruder remained in service for a few more years before being retired in favor of the LANTIRN-equipped F-14D Tomcat, which was in turn replaced by the F/A-18E/F Super Hornet in the U.S. Navy and the twin-seat F/A-18D Hornet in the U.S. Marine Corps. During the 2010s, the Unmanned Carrier-Launched Airborne Surveillance and Strike programme was at one point intended to produce an unmanned aerial vehicle (UAV) successor to the Intruder's long-distance strike role, but the initiative has since changed priorities towards the tanker mission instead.[28] The last Intruders were retired on 28 February 1997.

Many in the US defense establishment in general, and Naval Aviation in particular, questioned the wisdom of a shift to a shorter range carrier-based strike force, as represented by the Hornet and Super Hornet, compared to the older generation aircraft such as the Intruder and Tomcat. However, the availability of USAF Boeing KC-135 Stratotanker and McDonnell Douglas KC-10 Extender tankers modified to accommodate USN, USMC and NATO tactical aircraft in all recent conflicts was considered by certain senior decision makers in the Department of Defense to put a lesser premium on organic aerial refueling capability in the U.S. Navy's carrier air wings and self-contained range among carrier-based strike aircraft. Although the Intruder could not match the F-14's or the F/A-18's speed or air-combat capability, the A-6's range and load-carrying ability are still unmatched by newer aircraft in the fleet.[16]

At the time of retirement, several retired A-6 airframes were awaiting rewinging at the Northrop Grumman facility at St. Augustine Airport, Florida; these were later sunk off the coast of St. Johns County, Florida to form a fish haven named "Intruder Reef".[29] Surviving aircraft fitted with the new wings, as well as later production aircraft (i.e., BuNo 164XXX series) not earmarked for museum or non-flying static display were stored at the AMARG storage center at Davis-Monthan Air Force Base, Arizona.[30]

Variants

YA-6A and A-6A
A-6A of VMA (AW)-242 in 1975

The eight prototypes and pre-production Intruder aircraft were sometimes referred to with the YA-6A designation.[31] These were used in the development and testing of the A-6A Intruder.

The initial version of the Intruder was built around the complex and advanced DIANE (Digital Integrated Attack/Navigation Equipment) suite, intended to provide a high degree of bombing accuracy even at night and in poor weather. DIANE consisted of multiple radar systems: the Norden Systems AN/APQ-92 search radar replacing the YA-6A's AN/APQ-88, and a separate AN/APG-46 for tracking, the AN/APN-141 radar altimeter, and an AN/APN-122 Doppler navigational radar to provide position updates to the Litton AN/ASN-31 inertial navigation system. An air-data computer and the AN/ASQ-61 ballistics computer integrated the radar information for the bombardier/navigator in the right-hand seat. TACAN and ADF systems were also provided for navigation. When it worked, DIANE was perhaps the most capable navigation/attack system of its era, giving the Intruder the ability to fly and fight in even very poor conditions (particularly important over Vietnam and Thailand during the Vietnam War). It suffered numerous teething problems, and it was several years before its reliability was established.

A-6B on the USS Saratoga in 1971

Total A-6A production was 480, excluding the prototype and pre-production aircraft.[31] A total of 47 A-6As were converted to other variants.[31]

A-6B

To provide U.S. Navy squadrons with a defense suppression aircraft to attack enemy antiaircraft defense and SAM missile systems, a mission dubbed "Iron Hand" by the U.S. Navy, 19 A-6As were converted to A-6B version during 1967 to 1970.[32] The A-6B had many of its standard attack systems removed in favor of specialized equipment to detect and track enemy radar sites and to guide AGM-45 Shrike and AGM-78 Standard anti-radiation missiles, with AN/APQ-103 radar replacing earlier AN/APQ-92 used in the A-6A, plus AN/APN-153 navigational radar replacing earlier AN/APN-122, again used in the A-6A.

Between 1968 and 1977, several Intruder squadrons operated A-6Bs alongside their regular A-6As. Five were lost to all causes, and the survivors were later converted to A-6E standard in the late 1970s.

A-6C
A-6C of VA-35 Black Panthers

12 A-6As were converted in 1970 to A-6C standard for night attack missions against the Ho Chi Minh Trail in Vietnam. They were fitted with a "Trails/Roads Interdiction Multi-sensor" (TRIM) pod in the fuselage for FLIR and low-light TV cameras, as well as a "Black Crow" engine ignition detection system. Radars were also upgraded, with the AN/APQ-112 replacing the earlier AN/APQ-103, and an AN/APN-186 navigational radar replacing the earlier AN/APN-153. A vastly improved Sperry Corporation AN/APQ-127 radar replaced the AN/APG-46 fire control radar. One of these aircraft was lost in combat; the others were later refitted to A-6E standard after the war.

KA-6D
A KA-6D refueling an F-14A in 1987

To replace both the KA-3B and EA-3B Skywarrior during the early 1970s, 78 A-6As and 12 A-6Es were converted for use as tanker aircraft, providing aerial refueling support to other strike aircraft. The DIANE system was removed and an internal refueling system was added, sometimes supplemented by a D-704 refueling pod on the centerline pylon. The KA-6D theoretically could be used in the day/visual bombing role, but it apparently never was, with the standard load-out being four fuel tanks. Because it was based on a tactical aircraft platform, the KA-6D provided a capability for mission tanking, the ability to keep up with strike aircraft and refuel them in the course of a mission. A few KA-6Ds went to sea with each Intruder squadron. Their operation was integrated into the Intruder squadrons, as A-6 crew were trained to operate both aircraft and the NATOPS covered both the A6 and KA-6D. These aircraft were always in short supply, and frequently were "cross decked" from a returning carrier to an outgoing one. Many KA-6 airframes had severe G restrictions, as well as fuselage stretching due to almost continual use and high number of catapults and traps. The retirement of the aircraft left a gap in US Navy and Marine Corps refueling tanker capability. The Navy Lockheed S-3 Viking filled that gap until the new F/A-18E/F Super Hornet became operational.

A-6E
An A-6E Intruder of VA-34 flying over Spain during Exercise Matador.

The definitive attack version of the Intruder with vastly upgraded navigation and attack systems, introduced in 1970 and first deployed on 9 December 1971. The earlier separate search and track (fire control) radars of the A-6A/B/C were replaced by a single Norden AN/APQ-148 multi-mode radar, and onboard computers with a more sophisticated (and generally more reliable) IC based system, as opposed to the A-6A's DIANE discrete transistor-based technology. A new AN/ASN-92 inertial navigation system was added, along with the CAINS (Carrier Aircraft Inertial Navigation System), for greater navigation accuracy.

Final VA-34 A-6E Intruder launch from the flight deck of USS George Washington, 1996.

Beginning in 1979, all A-6Es were fitted with the AN/AAS-33 DRS (Detecting and Ranging Set), part of the "Target Recognition and Attack Multi-Sensor" (TRAM) system, a small, gyroscopically stabilized turret, mounted under the nose of the aircraft, containing a FLIR boresighted with a laser spot-tracker/designator and IBM AN/ASQ-155 computer. TRAM was matched with a new Norden AN/APQ-156 radar. The BN could use both TRAM imagery and radar data for extremely accurate attacks, or use the TRAM sensors alone to attack without using the Intruder's radar (which might warn the target). TRAM also allowed the Intruder to autonomously designate and drop laser-guided bombs. In addition, the Intruder used Airborne Moving Target Indicator (AMTI), which allowed the aircraft to track a moving target (such as a tank or truck) and drop ordnance on it even though the target was moving. Also, the computer system allowed the use of Offset Aim Point (OAP), giving the crew the ability to drop on a target unseen on radar by noting coordinates of a known target nearby and entering the offset range and bearing to the unseen target.

In the 1980s, the A-6E TRAM aircraft were converted to the A-6E WCSI (Weapons Control System Improvement) version to add additional weapons capability. This added the ability to carry and target some of the first generation precision guided weapons, like the AGM-84 Harpoon missile, and AGM-123 Skipper. The WCSI aircraft was eventually modified to have a limited capability to use the AGM-84E SLAM standoff land attack missile. Since the Harpoon and SLAM missiles had common communication interfaces, WCSI aircraft could carry and fire SLAM missiles, but needed a nearby A-6E SWIP to guide them to target.

Norden AN/APQ-148 Radar[33]

In the early 1990s, some surviving A-6Es were upgraded under SWIP (Systems/Weapons Improvement Program) to enable them to use the latest precision-guided munitions, including AGM-65 Mavericks, AGM-84E SLAMs, AGM-62 Walleyes and the AGM-88 HARM anti-radiation missile as well as additional capability with the AGM-84 Harpoon. A co-processor was added to the AN/ASQ-155 computer system to implement the needed MIL-STD-1553 digital interfaces to the pylons, as well as an additional control panel. After a series of wing-fatigue problems, about 85% of the fleet was fitted with new graphite/epoxy/titanium/aluminum composite wings. The new wings proved to be a mixed blessing, as a composite wing is stiffer and transmits more force to the fuselage, accelerating fatigue in the fuselage. In 1990, the decision was made to terminate production of the A-6. Through the 1970s and 1980s, the A-6 had been in low-rate production of four or five new aircraft a year, enough to replace mostly accidental losses. The final production order was for 20 aircraft of the SWIP configuration with composite wings, delivered in 1993.

A-6E models totaled 445 aircraft, about 240 of which were converted from earlier A-6A/B/C models.

A-6F and A-6G
A-6F prototype in 1987

An advanced A-6F Intruder II was proposed in the mid-1980s that would have replaced the Intruder's elderly Pratt & Whitney J52 turbojets with non-afterburning versions of the General Electric F404 turbofan used in the F/A-18 Hornet, providing substantial improvements in both power and fuel economy. The A-6F would have had totally new avionics, including a Norden AN/APQ-173 synthetic aperture radar and multi-function cockpit displays – the APQ-173 would have given the Intruder air-to-air capacity with provision for the AIM-120 AMRAAM. Two additional wing pylons were added, for a total of seven stations.

Although five development aircraft were built, the U.S. Navy ultimately chose not to authorize the A-6F, preferring to concentrate on the A-12 Avenger II. This left the service in a quandary when the A-12 was canceled in 1991.

Grumman proposed a cheaper alternative in the A-6G, which had most of the A-6F's advanced electronics, but retained the existing engines.[34] This, too, was canceled.

Electronic warfare versions
Main article: Northrop Grumman EA-6B Prowler
US Marine Corps EA-6A Intruder electronics aircraft of VMCJ-2 Playboys aboard USS America in 1974 during a visit to Scotland.

An electronic warfare (EW)/Electronic countermeasures (ECW) version of the Intruder was developed early in the aircraft's life for the USMC, which needed a new ECM platform to replace its elderly F3D-2Q Skyknights. An EW version of the Intruder, initially designated A2F-1H (rather than A2F-1Q, as "Q" was being split to relegate it to passive electronic warfare and "H" to active) and subsequently redesignated EA-6A, first flew on 26 April 1963. It had a Bunker-Ramo AN/ALQ-86 ECM suite, with most electronics contained on the walnut-shaped pod atop the vertical fin. They were equipped with AN/APQ-129 fire control radar, and theoretically capable of firing the AGM-45 Shrike anti-radiation missile, although they were apparently not used in that role. The navigational radar is AN/APN-153.

Only 28 EA-6As were built (two prototypes, 15 new-build, and 11 conversions from A-6As), serving with U.S. Marine Corps squadrons in Vietnam. It was phased out of front line service in the mid-1970s, remaining in use in reserve VMCJ units with the USMC and then the United States Navy in specialized VAQ units, primarily for training purposes. The last EA-6A had been retired by 1993.

A much more highly specialized derivative of the Intruder was the EA-6B Prowler, having a "stretched" airframe with two additional systems operators, and more comprehensive systems for the electronic warfare and SEAD roles. A derivative of AN/APQ-156, AN/APS-130 was installed as the main radar for EA-6B. The navigational radar was upgraded to AN/APS-133 from the AN/APN-153 on EA-6A. In total, 170 were produced. The EA-6B took on the duties of the U.S. Air Force EF-111 Raven when the DoD decided to let the U.S. Navy handle all electronic warfare missions. The Prowler has been replaced by the EA-18G Growler in the U.S. Navy and was retired from USMC service in 2019.

Variant list
YA2F-1
Pre-production aircraft, eight built with the first four with rotating jet exhaust pipes, redesignated YA-6A in 1962.[35]
A2F-1
First production variant with fixed tailpipe, 484 built, redesignated A-6A in 1962.[35]
YA2F-1H
Prototype electronic warfare variant, one modified from A2F-1, redesignated YEA-6A in 1962.[35]
A2F-1H
Electronic warfare variant of the A2F-1 redesignated EA-6A in 1962[35]
YA-6A
Pre-production aircraft redesignated from YA2F-1 in 1962.[35]
A-6A
First production variant redesignated from A2F-1 in 1962.[35]
YEA-6A
One YA2F-1 electronic warfare variant prototype redesignated in 1962.[35]
EA-6A
Electronic warfare variant redesignated from A2F-1H, had a redesigned fin and rudder and addition of an ECM radome, able to carry underwing ECM pods, three YA-6A and four A-6As converted and 21 built.[35]
NA-6A
The redesignation of three YA-6As and three A-6As. The six aircraft were modified for special tests.[35]
NEA-6A
One EA-6A aircraft was modified for special test purposes.[35]
TA-6A
Proposed trainer variant with three-seat, not built.[35]
A-6B
Variant fitted with avionics for the suppression of enemy air defenses (SEAD), 19 conversions from A-6A.[19]
EA-6B Prowler
Electronic warfare variant of the A-6A with longer fuselage for four crew.[35]
YEA-6B
The designation of two EA-6B prototypes, which were modified for special test purposes.
A-6C
A-6A conversion for low-level attack role with electro-optical sensors, twelve converted.[35]
KA-6D
A-6A conversion for flight-refueling, 58 converted.[35]
A-6E Intruder of VA-52, 1981
A-6E
A-6A with improved electronics.[35]
A-6F Intruder II
Advanced version with updated electronics and General Electric F404 turbofans; only 5 built.
A-6G
Proposed cheaper alternative to the A-6F, with its advanced electronics, but existing J52 turbojets.
G-128-12
Unbuilt single-seat A-6 based design proposal for the VA(L) competition for A-4 Skyhawk replacement based on existing design. Contract ultimately awarded to the LTV A-7 Corsair II.[36]

Operators
See also: List of A-6 Intruder operators
 United States

Aircraft on display
A Grumman A-6 Intruder on display at Grumman Memorial Park
An A-6 Intruder on display at the Udvar-Hazy Center.
An A-6F Intruder prototype on display at the Intrepid Sea-Air-Space Museum, New York City
An A-6E Intruder on display at Patuxent River Naval Air Museum
For EA-6A and EA-6B, see Northrop Grumman EA-6B Prowler.
A-6A
KA-6D
A-6E
A-6F

Specifications (A-6E)
Orthographic projection of an A-6 Intruder
A-6 ordnance, 1962

Data from Jane's All The World's Aircraft 1982–83[77] Jet Bombers: From the Messerschmitt Me 262 to the Stealth B-2[78]

General characteristics

  • Crew: 2 (pilot, bombardier/navigator)
  • Length: 54 ft 9 in (16.69 m)
  • Wingspan: 53 ft 0 in (16.15 m)
  • Width: 25 ft 2 in (7.67 m) wing folded
  • Height: 16 ft 2 in (4.93 m)
  • Wing area: 528.9 sq ft (49.14 m2)
  • Aspect ratio: 5.31:1[79]
  • Empty weight: 26,660 lb (12,093 kg)
  • Max takeoff weight: 60,400 lb (27,397 kg) (shore-based operations)
  • Fuel capacity: 2,385 US gal (1,986 imp gal; 9,030 L) (internal fuel)
  • Zero-lift drag coefficient: 0.0144[79]
  • Powerplant: 2 × Pratt & Whitney J52-P8B turbojets, 9,300 lbf (41 kN) thrust each

Performance

  • Maximum speed: 560 kn (640 mph, 1,040 km/h) at sea level
  • Cruise speed: 412 kn (474 mph, 763 km/h)
  • Stall speed: 98 kn (113 mph, 181 km/h) (flaps down)
  • Never exceed speed: 700 kn (810 mph, 1,300 km/h)
  • Combat range: 878 nmi (1,010 mi, 1,626 km) (with max payload)
  • Ferry range: 2,818 nmi (3,243 mi, 5,219 km)
  • Service ceiling: 42,400 ft (12,900 m)
  • g limits: -2.4 to 6.5
  • Rate of climb: 7,620 ft/min (38.7 m/s)
  • Lift-to-drag: 15.2[79]
  • Take-off run to 50 ft (15 m): 4,530 ft (1,380 m)
  • Landing run from 50 ft (15 m): 2,540 ft (770 m)

Armament

Notable appearances in media
Main article: Aircraft in fiction § A-6 Intruder

See also

Related development

Aircraft of comparable role, configuration, and era

Related lists

References

Notes
  1. Which technically capable of carrying 30 bombs, the rear inboard position of the Multiple Ejector Racks on hardpoints 2 and 4 (internal wing) had to be left clear to allow the landing gear to retract freely.

Citations
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  2. Jenkins 2002, pp. 5–6.
  3. Gunston and Gilchrist 1993, p. 209.
  4. Jenkins 2002, pp. 6–7.
  5. Jenkins 2002, p. 7.
  6. "Lawrence Mead Jr., Aerospace Engineer, Dies at 94." The New York Times, 30 August 2012.
  7. Jenkins 2002, p. 11.
  8. Dorr World Air Power Journal Spring 1993, p. 40.
  9. Dorr World Air Power Journal Spring 1993, p. 41.
  10. Dorr Air International November 1986, p. 228.
  11. Gunston and Gilchrist 1993, p. 210.
  12. Andrews, Hal. "Life of the Intruder". Naval Aviation News, Volume 79, No. 6, September–October 1997, pp 8-16. Cite magazine requires |magazine= (help)
  13. Gunston and Gilchrist 1993, pp. 210-211.
  14. "Northrup Grumman". Flight International. 23 October 1996.
  15. Gunston and Gilchrist 1993, p. 211.
  16. Trimble, Stephen (4 April 2011). "US naval aviation back on the rise". Flight International.
  17. Gunston and Gilchrist 1993, p. 211-212.
  18. Gunston and Gilchrist 1993, p. 212.
  19. Andrews, Hal. "Life of the Intruder". Naval Aviation News, VOLUME 79, No. 6, September–October 1997, pp 8-16. Cite magazine requires |magazine= (help)
  20. Gunston and Spick 1983,
  21. Hobson 2001, pp. 269–270.
  22. "4th December 1983". The Year 1983. Ejection History. 23 June 2011. Archived from the original on 21 September 2013. Retrieved 11 September 2013. A-6E TRAM BuNo 152915 coded AC, side number 556 VA-85 "Black Falcons" ... Near Kfar Salwan, 15 M E of Beirut, Lebanon, shot down by Syrian SAM-7 during bombing. Lt. Mark "Doppler" Lange ejected ... BN Robert O. "Bobby" Goodman ejected ...
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  28. Trimble, Stephen (3 August 2007). "Northrop Grumman wins US Navy unmanned bomber contract". Flight International.
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  78. Gunston and Gilchrist 1993, p. 213.
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