"A-10" redirects here. For other uses, see A10
The Fairchild Republic A-10 Thunderbolt II is a single-seat, twin turbofan engine, straight wing jet aircraft developed by Fairchild-Republic for the United States Air Force (USAF). Commonly referred to by the nicknames "Warthog" or "Hog", its official name comes from the Republic P-47 Thunderbolt, a World War II fighter that was effective at attacking ground targets. The A-10 was designed for close air support (CAS) of friendly ground troops, attacking armored vehicles and tanks, and providing quick-action support against enemy ground forces. It entered service in 1976 and is the only production-built aircraft that has served in the USAF that was designed solely for CAS. Its secondary mission is to provide forward air controller – airborne (FAC-A) support, by directing other aircraft in attacks on ground targets. Aircraft used primarily in this role are designated OA-10.
The A-10 was intended to improve on the performance of the A-1 Skyraider and its poor firepower. The A-10 was designed around the 30 mm GAU-8 Avenger rotary cannon. Its airframe was designed for durability, with measures such as 1,200 pounds (540 kg) of titanium armor to protect the cockpit and aircraft systems, enabling it to absorb a significant amount of damage and continue flying. Its short takeoff and landing capability permits operation from airstrips close to the front lines, and its simple design enables maintenance with minimal facilities. The A-10 served in the Gulf War (Operation Desert Storm), the American intervention against Iraq's invasion of Kuwait, where the A-10 distinguished itself. The A-10 also participated in other conflicts such as Operation Urgent Fury in Grenada, the Balkans, Afghanistan, Iraq, and against ISIL in the Middle East.
HOG UP and Wing Replacement Program
In 1987, Grumman Aerospace took over support for the A-10 program. In 1993, Grumman updated the damage tolerance assessment and Force Structural Maintenance Plan and Damage Threat Assessment. Over the next few years, problems with wing structure fatigue, first noticed in production years earlier, began to come to the fore. The process of implementing the maintenance plan was greatly delayed by the base re-alignment and closure commission (BRAC), which led to 80% of the original workforce being let go.
During inspections in 1995 and 1996, cracks at the WS23 location were found on many aircraft, most of them in line with updated predictions from 1993. However, two of these were classified as "near-critical" size, well beyond predictions. In August 1998, Grumman produced a new plan to address these issues and increase life span to 16,000 hours. This resulted in the "HOG UP" program, which commenced in 1999. Over time, additional aspects were added to HOG UP, including new fuel bladders, changes to the flight control system and inspections of the engine nacelles. In 2001, the cracks were reclassified as "critical", which meant they were considered repairs and not upgrades, which allowed bypassing normal acquisition channels for more rapid implementation.
An independent review of the HOG UP program at this point concluded that the data the wing upgrade relied on could no longer be trusted. This independent review was presented in September 2003. Shortly thereafter fatigue testing on a test wing failed prematurely and it became clear that there were also mounting problems with wings failing in-service inspections at an increasing rate. The Air Force estimated that they would run out of wings by 2011. Of the plans explored, replacing the wings with new ones was the least expensive with an initial cost of $741 million, and a total cost of $1.72 billion over the life of the program.
In 2005, a business case was developed with three options to extend the life of the fleet. The first two options involved expanding the service life extension program (SLEP) at a cost of $4.6 billion and $3.16 billion respectively. The third option, worth $1.72 billion, was to build 242 new wings and avoid the cost of expanding the SLEP. In 2006, option 3 was chosen and Boeing won the contract. The base contract is for 117 wings with options for 125 additional wings. In 2013, the Air Force exercised a portion of the option to add 56 wings, putting 173 wings on order with options remaining for 69 additional wings. In November 2011, two A-10s flew with the new wings fitted. The new wings improved mission readiness, decreased maintenance costs, and allowed the A-10 to be operated up to 2035 if necessary. The re-winging effort was organized under the thick-skin urgent spares kitting (TUSK) program.
In 2014, as part of plans to retire the A-10, the USAF considered halting the wing replacement program to save an additional $500 million; however, by May 2015 the re-winging program was too far into the contract to be financially efficient to cancel. Boeing stated in February 2016 that the A-10 fleet with the new TUSK wings could operate to 2040.
A-10C Warthog cockpit at the Smithsonian National Air and Space Museum 2012 Become a Pilot Day
In 2005, the entire fleet of 356 A-10 and OA-10 aircraft began receiving the Precision Engagement upgrades including an improved fire control system (FCS), electronic countermeasures (ECM), and smart bomb targeting. The aircraft receiving this upgrade were redesignated A-10C. The Government Accounting Office in 2007 estimated the cost of upgrading, refurbishing, and service life extension plans for the A-10 force to total $2.25 billion through 2013.In July 2010, the USAF issued Raytheon a contract to integrate a Helmet Mounted Integrated Targeting (HMIT) system into the A-10C. The Air Force Material Command's Ogden Air Logistics Center at Hill AFB, Utah completed work on its 100th A-10 precision engagement upgrade in January 2008. The final aircraft was upgraded to A-10C configuration in June 2011. The aircraft also received all-weather combat capability, and a Hand-on-Throttle-and-Stick configuration mixing the F-16's flight stick with the F-15's throttle. Other changes included two multifunction displays, a modern communications suite including a Link-16 radio and SATCOM. The LASTE system was replaced with the integrated flight and fire control computer (IFFCC) included in the PE upgrade.
Throughout its life, the platform's software has been upgraded several times and although these upgrades were due to be stopped as part of plans to retire the A-10 in February 2014, Secretary of the Air Force Deborah Lee James ordered that the latest upgrade, designated Suite 8, continue in response to Congressional pressure. Suite 8 software includes IFF Mode 5, which modernizes the ability to identify the A-10 to friendly units. Additionally, the Pave Penny pods and pylons are being removed as their receive-only capability has been replaced by the AN/AAQ-28(V)4 LITENING AT targeting pods or Sniper XR targeting pod, which both have laser designators and laser rangefinders.
In 2012, Air Combat Command requested the testing of a 600-gallon external fuel tank which would extend the A-10's loitering time by 45–60 minutes; flight testing of such a tank had been conducted in 1997, but did not involve combat evaluation. Over 30 flight tests were conducted by the 40th Flight Test Squadron to gather data on the aircraft's handling characteristics and performance across different load configurations. It was reported that the tank slightly reduced stability in the yaw axis, but there was no decrease in aircraft tracking performance.
A-10 inboard profile drawing
The A-10 has a cantilever low-wing monoplane wing with a wide chord. The aircraft has superior maneuverability at low speeds and altitude because of its large wing area, high wing aspect ratio, and large ailerons. The wing also allows short takeoffs and landings, permitting operations from primitive forward airfields near front lines. The aircraft can loiter for extended periods and operate under 1,000 ft (300 m) ceilings with 1.5 mi (2.4 km) visibility. It typically flies at a relatively low speed of 300 knots (350 mph; 560 km/h), which makes it a better platform for the ground-attack role than fast fighter-bombers, which often have difficulty targeting small, slow-moving targets.
The leading edge of the wing has a honeycomb structure panel construction, providing strength with minimal weight; similar panels cover the flap shrouds, elevators, rudders and sections of the fins. The skin panels are integral with the stringers and are fabricated using computer-controlled machining, reducing production time and cost. Combat experience has shown that this type of panel is more resistant to damage. The skin is not load-bearing, so damaged skin sections can be easily replaced in the field, with makeshift materials if necessary. The ailerons are at the far ends of the wings for greater rolling moment and have two distinguishing features: The ailerons are larger than is typical, almost 50 percent of the wingspan, providing improved control even at slow speeds; the aileron is also split, making it a deceleron.
The A-10 is designed to be refueled, rearmed, and serviced with minimal equipment. Its simple design enables maintenance at forward bases with limited facilities. Also, most repairs can be done in the field. An unusual feature is that many of the aircraft's parts are interchangeable between the left and right sides, including the engines, main landing gear, and vertical stabilizers. The sturdy landing gear, low-pressure tires and large, straight wings allow operation from short rough strips even with a heavy aircraft ordnance load, allowing the aircraft to operate from damaged airbases, flying from taxiways or even straight roadway sections.
Front view of an A-10 showing the 30 mm cannon and offset front landing gear
The front landing gear is offset to the aircraft's right to allow placement of the 30 mm cannon with its firing barrel along the centerline of the aircraft. During ground taxi, the offset front landing gear causes the A-10 to have dissimilar turning radii. Turning to the right on the ground takes less distance than turning left.[Note 1] The wheels of the main landing gear partially protrude from their nacelles when retracted, making gear-up belly landings easier to control and less damaging. All landing gears are hinged toward the aircraft's rear; if hydraulic power is lost, a combination of gravity and aerodynamic drag can open and lock the gear in place.