Grumman A-6F Intruder II 162185

The origins of the A-6 Intruder came in a 1957 Navy specification for a new attack aircraft to replace the aging Douglas AD-1/A-1 Skyraiders. The Marine Corps initiated the request with a desire for a Close Air Support (CAS) aircraft capable of short takeoff. At the same time, however, the Navy's experience in the Korean War showed the need for a new long-range strike aircraft with high subsonic performance at tree-top height to permit under-the-radar penetration of enemy defenses and to be capable of finding and hitting small and moving targets in any weather. Thus, the final specifications combined both missions, giving requirements for speed, range, weight, and payload, but left the numbers and type of engines to the bidders. The specifications also included a new wrinkle: unlike prior invitations, this one required the bidders to design and integrate the entire weapons system rather than having another manufacturer supply the equipment for later installation.

 

Grumman's design won out. Designated as the A2F Intruder (re-designated the A-6 in 1962), it featured twin jet engines in the wing roots and side-by-side seating for the two-person crew, with the Bombardier/Navigator's seat slightly lower and further back to improve the pilot's view out the right side of the aircraft. The seating arrangement was possible because of the bulbous nose, which is necessary to house the significant target acquisition and tracking radar and a separate, smaller terrain radar. Input from these and other instruments fed into a central computer system, the Digital Integrated Attack and Navigation Equipment (DIANE), which drove new Cathode Ray Tube (CRT) displays—one of the first times these were used in an aircraft—to guide the pilot in navigation and bombing. The DIANE system was critical to the Intruder's all-weather ability. The Intruder's shape led to nicknames like "Flying Drumstick" and "Iron Tadpole," along with the more general "Double Ugly."

 

Initial orders for the Intruder were placed in March of 1959 for eight YA2F-1 development aircraft. The first one flew on April 19th, 1960. The original design featured jet tailpipes that tilted down 23° to help shorten takeoffs and landings. However, testing with the YA2F-1s showed that this made no difference, so the feature was removed from production aircraft along with other changes due to testing. The YA2F-1s also added strengthened nose gear to accommodate the Navy's new nose-tow catapult system that replaced the older bridle-tow system. The Intruder was the first to have the new tow bar on the nose gear after Grumman's W2F-1/E-2A Hawkeye early warning airplane, designed around the same time as the Intruder.

 

The first A-6As were delivered to the U.S. Navy in 1963 and the Marines Corps in 1964. The first operational squadron to receive them was VA-75 ("Sunday Punchers"), which began supporting U.S. forces in Vietnam in 1965, flying off of the carrier USS Independence. The A-6's all-weather capability, enabled by the Digital Integrated Attack and Navigation Equipment (DIANE) and its subsystems, was a significant technological advancement. It allowed the crew to attack preselected targets at night or under adverse weather conditions without looking out of the cockpit during the mission (from launch to recovery). This capability greatly enhanced the aircraft's versatility and effectiveness in various combat scenarios.

 

As A-6 aircraft were produced, sophisticated electronics and delivery hardware developments were incorporated. 19 A models were modified to A-6Bs for "Iron Hand" missions (suppression of enemy anti-aircraft missiles). About a dozen aircraft became C models that carried a specialized belly pod called TRIM (Trails, Roads, Interdiction Multi-sensor) that included Low Light Level TV (LLLTV), Forward Looking Infrared (FLIR), and other specialized systems. TRIM was both heavy and unreliable. It was later replaced with a wing-mounted "Pave Knife" pod designed by the U.S. Air Force that added laser targeting and could be flown on many aircraft, not just the A-6. Properly used, Intruders were capable of delivering highly effective aerial attacks. For example, two A-6s made a nighttime strike, dropping 26 500 lb. bombs against a power plant in North Vietnam. The Vietnamese were convinced that B-52 bombers had been at work. A Distinguished Navy Cross was awarded for this mission.

 

The final variant of the Intruder, the A-6E, first flew in February 1970 as a modified A-6A. 240 A-6Es were rebuilt as A, B, and C models, with another 207 that Grumman manufactured new. The new model, featuring an updated avionics suite, airborne radar set, and a navigational computer, entered service with the VA-42 ("Green Pawns") training unit in 1971 and with VA-85 ("Black Falcons") as the first operational unit in December of that year.

 

The new radar set was a multi-mode radar that replaced the two single-mode radars in the A-6A. As a result, there was space available in the nose for new sensors, but the final design of those sensors took longer than anticipated. Grumman delivered most of the A-6Es (new and conversion) with accommodations to install the sensors later. These sensors ultimately became a chin-mounted pod known as TRAM (Target Recognition Attack Multi-sensor) that featured FLIR (Forward Looking Infra-Red camera), laser ranging and designation, and a laser sensor (so the bombardier/navigator could see targets designated by others) in a gyro-stabilized turret. The TRAM began coming into the fleet in 1979. Newly constructed Intruders had them installed on the production line, as did older Intruders converted after that, but most were retrofitted to aircraft in the field.

 

After fatigue problems were discovered in the A-6E fleet, new wings made from graphite/epoxy construction were developed and flown by 1987. In addition to the new composite wings, these aircraft were fitted with a digital armament system and a standoff weapons capability under the Systems Weapons Integration Program (SWIP).

 

Since Vietnam, the A-6s have made effective all-weather strikes against targets in Libya during the Gulf of Sidra crisis, Iranian gunboats in the Persian Gulf, and Iraqi installations during Desert Storm operations. TRAM-equipped A-6E Intruders were responsible for up to 85% of the laser designations and laser-guided bomb drops during Operation Desert Storm. The Intruder's last combat missions were over Bosnia in 1994. Despite its continued effectiveness, the A-6 Intruder was retired from frontline service in 1997, marking the end of an era in military aviation. Its retirement was a testament to the advancements in military technology and the changing nature of warfare.

 

This aircraft is not an ordinary A-6 but is, in fact, an A-6F Intruder II. This version was a more advanced A-6E that was proposed in the mid-1980s that would have replaced the Intruder's aging Pratt & Whitney J52 turbojets with non-afterburning versions of the General Electric F404 turbofan used in the F/A-18 Hornets, providing substantial improvements in both power and fuel economy. The A-6F would have had new avionics, including a Norden AN/APQ-173 synthetic aperture radar and multi-function cockpit displays—the AN/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 proceed with the A-6F, preferring to concentrate on the A-12 Avenger II. This would leave the service in a tight bind when the A-12 was also 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. This proposal would be canceled as well.

 

A total of five full-scale development A-6Fs were ordered. These aircraft were diverted from a batch of A-6Es (BuNos 162183-162187) and were known as "Intruder II." They were fitted with Grumman metal wings since Boeing's composite wings were not ready yet. BuNo 163183 was the aerodynamic and propulsion test vehicle and flew for the first time on August 26th, 1987, with Harry Hentx and Dave Goulette at the controls. BuNo 162184 followed on November 23rd. This aircraft, BuNo 162185, was the Digital Systems Development aircraft and was used as the testbed for the AN/APQ-173 radar and other advanced avionics systems. It flew for the first time on August 22nd, 1988. However, by this time, the A-6F project had already been canceled, and the last two A-6Fs had been mothballed from the fleet without having a chance to leave the ground.

Done