Aging Warplane, New Life
Upgraded weapons, electronics keep the A-10 Thunderbolt II a winning combat aircraft
By Christopher E. Camargo
U.S. ground combat troops fighting in Southeast Asia in the 1960s and Ô70s were supported from above by a slow, low-flying, heavily armed airplane that had been built for war in an earlier era. The piston-engine, propeller-driven Douglas A-1 Skyraider was designed as a World War II dive bomber but stayed in service for nearly three decades after being adapted for a ground-attack role. Although it could drop ordnance more accurately, absorb more damage and stay over the target longer than the fast-flying, fuel-gulping jets of the Vietnam War, the A-1’s service life ended as the military upgraded to all-turbine aircraft.
Its successor, the straight-wing, subsonic, twin-jet A-10 Thunderbolt II, was designed specifically with close-air support in mind. Introduced in the mid-1970s, the A-10 was equipped with free-falling bombs, missiles and a cannon that could destroy armored vehicles and tanks during low-level attacks.
Three decades later, today’s air combat arena is dominated by high-technology cruise missiles, unmanned aircraft and stealthy, fly-by-wire jets carrying precision weapons. Still, armed with new electronics and new precision weapons, the rugged and adaptable A-10 has defied obsolescence by excelling in close support of ground troops in Iraq and Afghanistan.
Like the A-1, the A-10A earned ground troops’ respect for its low-and-slow attacks, long loiter time and heavy armament. Those unique characteristics, plus the addition of modernized weapons-control, communications and navigation electronics, culminated in a new, precision-engagement-capable A-10C version that reached service in 2007. With those improvements, plus updated wings and possibly engines to increase performance, the A-10 is projected to remain in the U.S. Air Force fleet until at least 2028.
The A-10, manufactured by Fairchild-Republic Inc., was built for the rigors of low-altitude combat. Its forward fuselage was essentially built around a GAU-8A Avenger 30-millimeter, seven-barrel Gatling gun. Carrying cluster bombs and Maverick missiles under its long, straight wings, the A-10 was made for combat survivability and maneuverability in lieu of speed. Its single pilot is protected from ground fire by an armored cockpit. Twin rudders shield the engine exhaust from infrared heat-seeking missiles, a rugged landing gear allows operation from forward landing strips, and redundant control systems are designed to get the plane safely home despite battle damage.
Its analog controls, weapons systems, electronics and avionics were kept simple for ease of maintenance. However, that same simplicity turned into disadvantage as it limited the integration of more sophisticated navigation technology, such as global positioning systems, and precision-weapons technology as they became available in later years. Bringing a 1970s-vintage airplane into the digital, precision-weapons age created unique engineering challenges.
SwRI and the A-10
Engineers from Southwest Research Institute (SwRI) have been supporting the A-10 fleet since 1989 with design engineering modifications and upgrades designed to keep the vintage aircraft flying longer. The SwRI team initially supplied legacy weapon system support, system engineering, modifications and upgrades, electronic hardware design engineering, embedded applications software development and test and diagnostics development for the Sacramento Air Logistics Center. As part of that work, SwRI engineers inserted new technologies to complement or replace legacy systems for engine monitoring and data recording. They also have added improved support equipment and new technology for enhanced targeting, advanced navigation and better pilot situational awareness.
A-10 Prime Team
In 1997, with the airplane’s original manufacturer no longer in business, the U.S. Air Force awarded a contract to care for the A-10 fleet to a ÒPrime Team,Ó led by Lockheed Martin Systems Integration in Owego, NY. The team also comprised SwRI, BAE Systems and Northrop Grumman. Programs undertaken by the A-10 prime team have addressed large-scale systems, weapon systems, support equipment, structural engineering, maintenance and support, and aircraft trade studies.
The SwRI engineering team supported Lockheed Martin in bringing the A-10 into the world of network-centric warfare (NCW), which increases combat capability by tying together sensors, pilots, ground personnel and combat decision-makers. When networked in this way, warfighters can share combat awareness, increase the speed of command and maintain higher-tempo, synchronized operations for greater effectiveness and survivability.
SwRI avionics technicians retrofitted the new A-10C with a situational awareness data link (SADL) radio as an integral portion of NCW, providing the communications and networking capability for mobile forces that, together with the global information grid and communication satellites, enables robust enterprise-wide networking. The SADL provides communications and data transfer among combat aircraft, reconnaissance aircraft, ground vehicles and troops to share information about fighter status, targeting data and the positions of friendly troops.
Adding the SADL radio made possible greatly improved interoperability between the A-10C pilot and air and ground forces. The data link connects the A-10 to the “digital battlefield,” increases the pilot’s situational awareness to better avoid fratricide in combat situations, and enables field commanders to direct attacks on specific targets. SwRI engineers, in coordination with LMSI, also continued development of a modification kit to replace current aircraft identification systems with new transponders required for operating in European airspace.
In addition, SwRI engineers supported Lockheed Martin for the precision-engagement updates for the A-10C version by integrating advanced smart bombs into the weapons system. They also updated targeting and weapons release capability, enhancing the A-10 cockpit and providing updated flightline support equipment.
Other upgrades to the aging aircraft have included an improved pilot’s head-up display that uses multifunction color displays to add greater functionality for future growth and to show flight and weapons delivery information using standard symbology, and other cockpit enhancements to allow A-10C pilots to operate weapons and communications systems in combat while keeping their hands on the throttle and control stick.
SwRI engineers also performed upgrades to facilitate A-10 flightline maintenance. These included a tester to provide troubleshooting and diagnostic capabilities for maintenance on the integrated avionics and weapons systems, subsystems and sensors for both the A-10A and the new A-10C aircraft. The tester comprises a portable automated test station and operational test program software to verify the status of weapon stations using discrete data acquisition as well as through the airplane’s avionics bus. Meanwhile, using SwRI internal research funding they also developed a ruggedized, lightweight, hand-held device that acts as a remote terminal to download engine data used by the A-10 engine structural integrity program via the avionics bus. The mobile device enhances efficiency on the flightline while reducing the amount of support equipment needed.
An SwRI team went to Nellis Air Force Base, Nevada, for on-site support of flight test operations as part of the A-10C precision engagement program. There, they assisted with aircraft maintenance and post-mission pilot briefings and also provided training for Air Force maintenance crews.
Following flight testing, SwRI engineers also accompanied the A-10C crews to combat theaters in Afghanistan and Iraq, where the aircraft has proved to be highly successful in delivering smart weapons reliably and on-target.
In October, 2007, the A-10 Precision Engagement Program won the Department of Defense and National Defense Industrial Association’s 2006 Top 5 DoD Program award for excellence in systems engineering.
Besides enhancing the operational usefulness of the A-10, SwRI engineers addressed the structural integrity of the airframe as part of a multidisciplinary approach to help the military evaluate and extend the life of aging military systems. Because upgrades to extend service life by reinforcing wing components, expanding precision-weapons capabilities and improving communication data links all have implications for the airframe itself, the A-10 Prime Team is revitalizing the aircraft structural integrity program to sustain the aircraft as its flying hours increase and its usage expands.
A number of additional programs are planned to keep the A-10 a viable combat system through at least 2028. The Prime Team is investigating further upgrades to the pilot’s communication, navigation, surveillance and air traffic management capabilities. In addition, upgrades are planned for the Joint Tactical Radio System as well as avionics hardware and software. Further integration of a powerplant upgrade program and flight-test support, plus future aircraft structural integrity program support, are also planned.
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Published in the Spring 2008 issue of Technology Today®, published by Southwest Research Institute. For more information, contact Joe Fohn.