Misplaced Pages

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86-532: The Grumman A-6 Intruder is an American twinjet all-weather attack aircraft developed and manufactured by American aircraft company Grumman Aerospace and formerly operated by the U.S. Navy and U.S. Marine Corps . It was designed in response to a 1957 requirement issued by the Bureau of Aeronautics for an all-weather attack aircraft for Navy long-range interdiction missions and with short takeoff and landing (STOL) capability for Marine close air support. It

172-457: A Request For Proposals (RFP) in February 1957. The RFP 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. In response to

258-464: A defense suppression aircraft to attack enemy anti-aircraft defense and SAM systems, a mission dubbed " Iron Hand " by the U.S. Navy, 19 A-6As were converted to A-6B version during 1967 to 1970. 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

344-649: A great circle route. Hence, in case of an engine failure in a twinjet (like Boeing 777 ), the twin-jet could make emergency landings in fields in Canada , Alaska , eastern Russia , Greenland , Iceland , or the British Isles . The Boeing 777 has also been approved by the Federal Aviation Administration for flights between North America and Hawaii , which is the world's longest regular airline route with no diversion airports along

430-518: A podded engine usually mounted beneath, or occasionally above or within, each wing. Most notable examples of such a configuration are the Boeing 737 and Airbus A320 . The second has one engine mounted on each side of the rear fuselage, close to its empennage , used by many business jets , although some airliners like the Fokker 70 , Douglas DC-9 and COMAC ARJ21 utilise such a design as well. In

516-589: A 7 degree downward angle. 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". 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,

602-599: A US Navy A-6E performing the unusual target towing task to train Japanese Navy air defense crews was mistakenly engaged and shot down by the Japanese destroyer JS Yūgiri with its Phalanx CIWS gun. Both the pilot and BN ejected and were recovered. 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,

688-668: A cheaper alternative in the A-6G , which had most of the A-6F's advanced electronics, but retained the existing engines. This, too, was canceled. 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"

774-539: 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. 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

860-636: 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 program was at one point intended to produce an unmanned aerial vehicle (UAV) successor to

946-405: A high degree of integration. 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

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1032-427: A lot of development and changes had to be made to correct aerodynamic deficiencies and remove unwanted features. Extending the air brakes , which were mounted on the rear fuselage, changed the downwash at the horizontal tailplane which overloaded its actuator so the tailplane was moved rearwards by 16 inches (41 cm). Later evaluation of the aircraft showed that the airbrakes were not effective enough in controlling

1118-579: 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

1204-538: A number of nicknames, including "Double Ugly", "The Mighty Alpha Six", "Iron Tadpole" and also "Drumstick". 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. Navy A-6s saw further duty over Bosnia in 1994. On 4 June 1996, during RIMPAC

1290-622: 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. The A-6's wing was relatively efficient at subsonic speeds, particularly when compared to supersonic fighters such as

1376-408: A specified distance from an available diversion airport. Overwater flights near diversion airports need not be ETOPS/LROPS-compliant. Since the 1990s, airlines have increasingly turned from four-engine or three-engine airliners to twin-engine airliners to operate transatlantic and transpacific flight routes. On a nonstop flight from America to Asia or Europe, the long-range aircraft usually follows

1462-541: A trijet aircraft) and Boeing worked on new widebody twinjet designs that would become the Airbus A330 and Boeing 777 , respectively. The MD-11's long range advantage was brief as it was soon nullified by the Airbus A330-300 and the extended-range Boeing 767-300ER and Boeing 777-200ER. The Airbus A320 twinjet stands out as the most produced jet airliner. The Boeing 777X is the world's largest twinjet, and

1548-450: A type of flight control surface used on an aircraft to increase the drag on the aircraft. When extended into the airstream, air brakes cause an increase in the drag on the aircraft. When not in use, they conform to the local streamlined profile of the aircraft in order to help minimize drag. Air brakes differ from spoilers in that air brakes are designed to increase drag while making little change to lift , whereas spoilers reduce

1634-542: A wider chord at its base to give greater exposed area to assist spin recovery. A major difference between the first six production aircraft and subsequent aircraft were the jet nozzles; close-air support by the Marine Corps required STOL performance to operate from forward airstrips. Jet deflection using tilting tailpipes was proposed. The performance benefits from varying the angle were not worthwhile, whether operating from short strips or carriers, and they were fixed at

1720-715: 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. Twinjet There are three common configurations of twinjet aircraft. The first, common on large aircraft such as airliners, has

1806-408: Is a two-seat twin-engined monoplane, equipped to perform carrier-based attack missions regardless of prevailing weather or light conditions. 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 to give the pilot an adequate view on that side. In addition to

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1892-474: Is not an issue, as one of the engines is more than powerful enough to keep the aircraft aloft (see below). Mostly, ETOPS certification involves maintenance and design requirements ensuring that a failure of one engine cannot make the other one fail also. The engines and related systems need to be independent and (in essence) independently maintained. ETOPS/LROPS is often incorrectly thought to apply only to long overwater flights, but it applies to any flight more than

1978-518: The 777X in November 2013, while then-CEO Fabrice Brégier preferred to focus on product improvement rather than all-new concepts for 10 years. It would have a 10-abreast economy like the 777; its 565 m (6,081 sq ft) wing, slightly more than the 747-8, would have an 80 m (262 ft) span, as wide as the A380 , for a 892,900 lb (405 t) MTOW compared to 775,000 lb (352 t) for

2064-539: 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 forward-looking infra-red (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

2150-549: The Blackburn Buccaneer naval strike aircraft designed in the 1950s and Fokker F28 Fellowship and British Aerospace 146 airliners. The Buccaneer air brake, when opened, reduced the length of the aircraft in the confined space on an aircraft carrier . The F-15 Eagle , Sukhoi Su-27 , F-18 Hornet and other fighters have an air brake located just behind the cockpit . The deceleron is an aileron that functions normally in flight but can split in half such that

2236-399: The Boeing 777 , Boeing 787 and Airbus A350 have matched or surpassed older quad-jet designs such as the Boeing 747 and Airbus A340 in these aspects, and twinjets have been more successful in terms of sales than quad-jets. In 2012, Airbus studied a 470-seat twinjet competitor for the Boeing 747-8 with lower operating costs expected between 2023 and 2030, revived after Boeing launched

2322-814: 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 . 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. The Intruder's large blunt nose and slender tail inspired

2408-614: 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

2494-521: 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. For its day, the Intruder had sophisticated avionics , with

2580-601: 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; 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

2666-689: The Vietnam War . The A-6C , a dedicated interdictor, was one such model, as was the KA-6D , a buddy store -equipped aerial refueling 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. The last A-6E

Grumman A-6 Intruder - Misplaced Pages Continue

2752-617: The YA-6A designation. 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

2838-608: The lift-to-drag ratio and require a higher angle of attack to maintain lift, resulting in a higher stall speed . In the early decades of powered flight, air brakes were flaps mounted on the wings. They were manually controlled by a lever in the cockpit, and mechanical linkages to the air brake. An early type of air brake, developed in 1931, was fitted to the aircraft wing support struts. In 1936, Hans Jacobs , who headed Nazi Germany's Deutsche Forschungsanstalt für Segelflug (DFS) glider research organization before World War II, developed blade-style self-operating dive brakes, on

2924-627: 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 ). During

3010-753: The 777-200LR variant has the world's second longest aircraft range (behind Airbus A350-900 ULR). Other Boeing twinjets include the 767 , 757 (With the latter having stopped production, but still in commercial service) and 787 . Competitor Airbus produces the A320 family , the A330 , and the A350 . Some modern commercial airplanes still use four engines ( quad-jets ) like the Airbus A380 and Boeing 747-8 , which are classified as very large aircraft (over 400 seats in mixed-class configurations). Four engines are still used on

3096-432: The 777X, with a composite structure for an operating empty weight of 467,400 lb (212 t), and a 8,150 nmi (15,090 km) range at Mach 0.85. When flying far from diversionary airports (so called ETOPS/LROPS flights), the aircraft must be able to reach an alternate on the remaining engine within a specified time in case of one engine failure. When aircraft are certified according to ETOPS standards, thrust

3182-516: 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. The first prototype YA2F-1, lacking radar and the navigational and attack avionics, made its first flight on 19 April 1960, with the second prototype flying on 28 July 1960. The test program required to develop the aircraft took a long time. The very advanced navigation and attack equipment required

3268-450: 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 surviving aircraft were later converted to A-6E standard in the late 1970s. 12 A-6As were converted in 1970 to A-6C standard for night attack missions against

3354-549: 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. Beginning in 1979, all A-6Es were fitted with

3440-648: 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. The Intruder remained in service for

3526-512: 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. 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

Grumman A-6 Intruder - Misplaced Pages Continue

3612-655: 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

3698-505: The Intruder's long-distance strike role, but the initiative has since changed priorities towards the tanker mission instead. 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

3784-493: The Naval Avionics Lab launched a substantial and lengthy program to improve both the reliability and performance of the A-6's avionics suite. The successful performance of the A-6 in operations following these improvements ended proposals to produce follow-on models that featured downgraded avionics. Various specialized variants of the A-6 were developed, often in response to urgent military requirements raised during

3870-508: 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 . Grumman's submission was internally designated as the Type G-128 . 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

3956-457: 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 an 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,

4042-637: 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. 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

4128-751: 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

4214-685: 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

4300-450: The aircraft left a gap in US Navy and Marine Corps refueling tanker capability. At least 16 KA-6Ds served in the Gulf War . The Navy Lockheed S-3 Viking filled that gap until the new F/A-18E/F Super Hornet became operational. 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

4386-669: 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 nuclear weapons ( B43 , B57 , B61 ) which would have been delivered using semi-automated toss bombing . The Intruder received

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4472-528: The case of most airliners, lift spoilers that also act as air brakes. Propeller-driven aircraft benefit from the natural braking effect of the propeller when engine power is reduced to idle, but jet engines have no similar braking effect, so jet-powered aircraft must use air brakes to control speed and descent angle during landing approach. Many early jets used parachutes as air brakes on approach ( Arado Ar 234 , Boeing B-47 ) or after landing ( English Electric Lightning ). Split-tailcone air brakes have been used on

4558-472: The coast of St. Johns County , Florida to form a fish haven named "Intruder Reef". Surviving aircraft fitted with the new wings, and 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. The eight prototypes and pre-production Intruder aircraft were sometimes referred to with

4644-493: 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 'Weapons Control System Improvement' (WCSI) version to extend weapons capability. This added the ability to carry and target some of

4730-624: 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

4816-471: The deployment of these spoilers ("lift dumpers") causes a significant reduction in wing lift, so the weight of the aircraft is transferred from the wings to the undercarriage. The increased weight increases the available friction force for braking. In addition, the form drag created by the spoilers directly assists the braking effect. Reverse thrust is also used to help slow the aircraft after landing. Virtually all jet-powered aircraft have an air brake or, in

4902-549: The design was approved by the Mock-Up Review Board. 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

4988-607: The development of their submission, which had been re-designated A2F-1 , in February 1958. Grumman's design team was led by Robert Nafis and Lawrence Mead, Jr. Mead later played a lead role in the design of the Lunar Excursion Module and the Grumman F-14 Tomcat . The team was spread between two sites, the company's manufacturing plant at Bethpage and the testing facilities at Naval Weapons Industrial Reserve Plant, Calverton . During September 1959,

5074-583: 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

5160-420: The first generation precision guided weapons, like the AGM-84 Harpoon missile, and AGM-123 Skipper . WCSI equipped aircraft were 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. In

5246-479: The introduction of ETOPS rules that allowed twin-engine jets to fly long-distance routes that were previously off-limits to them, Airbus was able to further develop the A300 as a medium- to long-range airliner to increased sales; Boeing launched its widebody twinjet, the Boeing 767 , in response. In the 1980s the Boeing 727 was discontinued, as its central engine bay would require a prohibitively expensive redesign to accommodate quieter high-bypass turbofans, and it

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5332-449: The largest cargo aircraft capable of transporting outsize cargo , including strategic airlifters . Twin-jets tend to be more fuel-efficient than trijet (three engine) and quad-jet (four engine) aircraft. As fuel efficiency in airliners is a high priority, many airlines have been increasingly retiring trijet and quad-jet designs in favor of twinjets in the twenty-first century. The trijet designs were phased out first, in particular due to

5418-410: The more complicated design and maintenance issues of the middle engine mounted on the stabilizer. Early twinjets were not permitted by ETOPS restrictions to fly long-haul trans-oceanic routes, as it was thought that they were unsafe in the event of failure of one engine, so quad-jets were used. Quad-jets also had higher carrying capacity than comparable earlier twinjets. However, later twinjets such as

5504-405: The more successful variants developed were the EA-6B Prowler , a specialized electronic warfare derivative, and the KA-6D tanker version. 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

5590-409: 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

5676-403: 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

5762-425: The pilot and weapons officer (bombardier/navigator or BN). In addition to conventional munitions, it could also carry nuclear weapons , which would be delivered using toss bombing techniques. On 19 April 1960, the first prototype made its maiden flight . The A-6 was in service with the United States Navy and Marine Corps between 1963 and 1997, during which time multiple variants were prototyped and produced. Two of

5848-427: 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. 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. The Grumman A-6 Intruder

5934-710: The requirement that an aircraft be able to continue a takeoff if an engine fails after the takeoff decision speed is reached. Thus, with all engines operating, trijets must be able to produce at least 150% of the minimum thrust required to climb and quad-jets 133%. Conversely, since a twinjet will lose half of its total thrust if an engine fails, they are required to produce 200% of the minimum thrust required to climb when both engines are operating. Because of this, twinjets typically have higher thrust-to-weight ratios than aircraft with more engines, and are thus able to accelerate and climb faster. Air brake (aeronautics) In aeronautics , air brakes or speed brakes are

6020-400: The speed of the aircraft and they were moved to the wing-tips. Early production aircraft were fitted with both the fuselage and wingtip air brakes, although the fuselage-mounted ones were soon disabled, and were removed from later aircraft. The trailing edge of each wing-tip split to form a much more effective speed-brake which projected above and below the wing when extended. The rudder needed

6106-421: The third configuration both engines are within the fuselage, side-by-side, used by most fighters since the 1960s. Later fighters using this configuration include the Su-27 'Flanker', the F-15 Eagle , and the F-22 Raptor . The first twinjet to fly was the German fighter prototype Heinkel He 280 , flying in April 1941 with a pair of nacelled Heinkel HeS 8 axial-flow turbojets. The twinjet configuration

6192-744: The upper and lower surface of each wing, for gliders. Most early gliders were equipped with spoilers on the wings in order to adjust their angle of descent during approach to landing. More modern gliders use air brakes that may spoil lift as well as increase drag, dependent on where they are positioned. A British report written in 1942 discusses the need for dive brakes to enable dive bombers, torpedo bombers and fighter aircraft to meet their respective combat performance requirements and, more generally, glide-path control. It discusses different types of air brakes and their requirements, in particular that they should have no appreciable effect on lift or trim and how this may be achieved with split trailing edge flaps on

6278-1118: 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. 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 . A-6 Intruders were later used in support of other operations, such as

6364-521: 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

6450-450: The way. On large passenger jets, the cost of the engines makes up a significant proportion of the plane's final cost. Each engine also requires separate service, paperwork, and certificates. Having two larger engines as opposed to three or four smaller engines will typically significantly reduce both the purchase and maintenance costs of a plane. Regulations governing the required thrust levels for transport aircraft are typically based upon

6536-478: The wings, for example. There was also a requirement to vent the brake surfaces using numerous perforations or slots to reduce airframe buffeting. A US report written in 1949 describes numerous air brake configurations, and their performance, on wings and fuselage for propeller and jet aircraft. Often, characteristics of both spoilers and air brakes are desirable and are combined - most modern airliner jets feature combined spoiler and air brake controls. On landing,

6622-454: 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

6708-546: 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

6794-486: Was delivered in 1992. 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. Instead, a life-extension program involving

6880-491: 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. An advanced A-6F Intruder II

6966-507: 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. Total A-6A production was 480, excluding the prototype and pre-production aircraft. A total of 47 A-6As were converted to other variants. To provide U.S. Navy squadrons with

7052-490: 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 –

7138-688: Was scheduled for retirement, its precision strike mission was initially taken over by the Grumman F-14 Tomcat equipped with a LANTIRN pod. As a result of the fair-weather limitation of the propeller-driven A-1 Skyraider in the Korean War and the advent of turbine engines, the United States Navy issued preliminary requirements in 1955 for an all-weather carrier-based attack aircraft . The U.S. Navy published an Operational Requirements Document (ORD) for it in October 1956. It released

7224-656: Was soon supplanted by twinjets for the narrow-body market; Airbus with the A320 , and Boeing with the 757 and updated "classic" variants of the 737 . During that decade only McDonnell Douglas continued development of the trijet design with an update to the DC-10 , the MD-11 , which initially had a range advantage over its closest medium wide-body competitors which were twinjets, the in-production Boeing 767 and Airbus A300/A310. In contrast to McDonnell Douglas sticking with their existing trijet configuration, Airbus (which never produced

7310-412: Was to replace the piston-engined Douglas A-1 Skyraider . The requirement allowed one or two engines, either turbojet or turboprop. The winning proposal from Grumman used two Pratt & Whitney J52 turbojet engines. The Intruder was the first Navy aircraft with an integrated airframe and weapons system. Operated by a crew of two in a side-by-side seating configuration, the workload was divided between

7396-535: Was used for short-range narrow-bodied aircraft such as the McDonnell Douglas DC-9 and Boeing 737 . The Airbus A300 was initially not successful when first produced as a short-range widebody, as airlines operating the A300 on short-haul routes had to reduce frequencies to try and fill the high-capacity aircraft, and lost passengers to airlines operating more frequent narrow-body flights. However, after

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