Grumman A-6 Intruder / Originally Designed With Thrust Vectoring

a6_2The A-6 was the U.S. Navy’s all-weather long-range attack aircraft with the ability to operate day or night. It was a subsonic, two seat aircraft fitted with the ability to carry up to 15,000 lb or numerous types of munitions. Later A-6E’s were fitted with the Target Recognition and Attack Multisensor (TRAM), which included Forward Looking Infra-Red (FLIR) for precision-guided munitions. Over 660 A-6 aircraft were built.

In December 1957, the Grumman corporation was selected by the US Navy to fulfill the new long-range low-level tactical strike aircraft requirement with their A-6 Intruder. The A-6A’s first flight occurred on April 19, 1960, and the first of 482 production aircraft were delivered in February 1963. The A-6A introduced the new Digital Integrated Attack Navigation Equipment (DIANE), which proved to be excellent in all weather conditions.

In all, 19 A-6B’s were converted from A-6A standard for SAM suppression, and 12 A-6C’s were converted with FLIR and LLLTV equipment for improved night-attack capabilities. The upgraded A-6E first flew on February 27, 1970 and introduced a multi-mode navigation/attack radar system. The A-6 was later replaced by the F/A-18 Hornet.

The A-6E is an all-weather, two-seat, subsonic, carrier-based attack aircraft. In spite of its weight, it has excellent slow-flying capabilities with full span slats and flaps. The crew, sitting side by side, can see in all directions through a broad canopy. The aircraft is equipped with a micro-miniaturized digital computer, a solid state weapons release system, and a single integrated track and search radar. The Intruder is armed with laser-guided weapons and equipped with a chin turret containing a forward-looking infra-red (FLIR) system and laser designator and receiver.

The A-6 worked around the clock in Vietnam, conducting attacks on the targets with a pinpoint accuracy unavailable through any other aircraft at that time.The A-6E proved once again that it is the best all-weather precision bomber in the world in the joint strike on Libyan terrorist-related targets in 1986. Navy A-6E Intruders and Air Force FB-111s penetrated the sophisticated Libyan air defense systems, which had been alerted by the high level of diplomatic tension and by rumors of impending attacks. Evading more than 100 guided missiles, the strike force flew at low levels in complete darkness and hit its target. A-6 aircraft were used extensively during Operation Desert Storm, providing precision bombing on a wide range of targets. The night and all-weather attack capabilities enabled the A-6 to neutralize anti-aircraft batteries and attack well-protected tactical targets with minimum casualties. The precision munitions used by the A-6 provided exact targeting of targets in a complex environment.

Much more info HERE

The A-6 Intruder Was Originally Designed With Thrust Vectoring

The A-6 Intruder Was Originally Designed With Thrust Vectoring

As with so many military aircraft designs, the A-6 Intruder, known originally as the YA2F-1, had some pretty ambitious features that never really panned out. The jet’s swiveling exhausts were one of them.

The mid to late 1950’s were an incredible time for aerospace engineering as the world came to grips with the vast possibilities that jet power provided. The A-6 Intruder came out of a requirement for a deep penetrating all-weather precision attack platform. As part of this requirement, the Navy wanted the aircraft to be capable of short takeoffs and landings (STOL), even though it would mainly be hurtled from the decks of aircraft carriers via steam catapults and “trapped” back on deck via the use of a hook and arresting cable. Nonetheless, Grumman moved forward with the design requirements and came up with the Intruder’s unique silhouette that some describe as “a flying tadpole.”

The A-6 Intruder Was Originally Designed With Thrust Vectoring

The YA2F-1’s centrally mounted engine nacelles housed a pair of non-afterburner J-52 turbojets that produced a combined 18,600 lbs of thrust. The jet already had a large and relatively thick ring, but the STOL requirement would require more innovation than just a wing design. With this in mind, Grumman engineers designed the aircraft with a motor placement that could accommodate exhaust nozzles that would swivel up to 23 degrees downward. The idea was for the YA2F-1 to vector its thrust dynamically during its takeoff roll by rerouting the aircraft’s thrust downward, along the airframe’s vertical axis, thus shortening the aircraft’s takeoff distance. This same configuration, along with a unique trim setting, could also slow the stout aircraft’s approach speed, thus shortening its required landing distance.

The concept was innovative, and was certainly a forerunner of things to come with the famous Harrier Jump Jet years later, an aircraft that used rotating nozzles with fantastic results. This includes the Harrier’s “viffing” ability, where a pilot toggles its rotatable nozzles during air combat to decelerate quickly. One can only wonder what the Intruder could have been able to do when it comes to evading enemy fighters with its variable geometry nozzles.

In testing, the YA2F-1’s swiveling nozzles only significantly helped the aircraft get off the ground faster when it was lightly loaded, and only reduced the aircraft’s approach speed a few knots. Considering the added complexity, cost and training requirements that were involved with the unique exhausts, the idea was dropped on production models. Still, you can see this unique design element’s lasting mark on A-6s in museums and EA-6B Prowlers, the A-6 Intruder’s electronic attack sibling that is still flying, via the design’s low mounted engine nacelles and serpentine exhaust that is still canted slightly down and outward to avoid the aircraft’s long tailboom and tailplane.

The A-6 Intruder Was Originally Designed With Thrust Vectoring

In retrospect, the YA2F-1’s swiveling exhausts made a lot of sense, just not for the Intruder, an aircraft that would spend its decades long career often loaded down with thousands upon thousands of pounds of gas and dozens of 500lb bombs and other munitions. A light attack aircraft, or light fighter would have benefited better from the swiveling exhaust technology than the beast of burden, bomb truck of a jet that was to become the Intruder. Although I am sure that there are some Marine Corps A-6 pilots who would swear to you that every foot less of runway needed to get their max-loaded A-6 off the ground on a hot day in South Vietnam was worth the complexity and the cost of the swiveling nozzles!

The A-6 Intruder Was Originally Designed With Thrust Vectoring

Fast forward to today, and STOL is still a very important requirement for some air arms, and the ultra complex and super-expensive F-35B, that also features a downward swiveling exhaust, is proof of this.

Regardless of Grumman’s failed attempt at fitting this unique thrust vectoring concept to their prototype Intruders, the aircraft would go on to set the bar when it comes to range and payload capabilities for the US Navy. A bar which has never been raised since its retirement in 1997.

Some would say that the Intruder’s long legs, massive weapons carrying ability, highly efficient side by side cockpit arrangement and incredible tanking ability (in the form of the KA-6D) would have proven to be more valuable in the wars of the last decade than the pointy nosed, fuel hungry fighters that remained in Marine Corps and Navy inventory long after its demise, but this is another story, one that I will save for next week…

The A-6 Intruder Was Originally Designed With Thrust Vectoring

Photo Credit: USN, USMC, NAVAIR, Grumman

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