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| A-10 Thunderbolt II | |
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| An A-10 from the 81st Fighter Squadron, Spangdahlem Air Base, Germany | |
| Role | Fixed-wing close air support, forward air control, and ground-attack aircraft |
| Manufacturer | Fairchild Republic |
| First flight | 10 May 1972 |
| Introduction | March 1977 |
| Status | In service |
| Primary user | United States Air Force |
| Produced | 1972–1984[1] |
| Number built | 716[2] |
| Unit cost | US$11.8 million (average, 1994 dollars)[3] |
The A-10 was designed around the GAU-8 Avenger, a rotary cannon that is the airplane's primary armament and the heaviest such cannon mounted on an aircraft. The A-10's airframe was designed for survivability, with protective measures such as 1,200 pounds (540 kg) of armor to enable the aircraft to continue flying after taking damage. The A-10's official name comes from the Republic P-47 Thunderbolt of World War II, a fighter that was particularly effective at close air support. The A-10 is more commonly known by its nicknames "Warthog" or "Hog".
Contents
Development
Background
Criticism that the U.S. Air Force did not take close air support (CAS) seriously prompted a few service members to seek a specialized attack aircraft.[4][5] In the Vietnam War, large numbers of ground-attack aircraft were shot down by small arms, surface-to-air missiles, and low-level anti-aircraft gunfire, prompting the development of an aircraft better able to survive such weapons. In addition, the UH-1 Iroquois and AH-1 Cobra helicopters of the day, which USAF commanders had said should handle close air support, were ill-suited for use against armor, carrying only anti-personnel machine guns and unguided rockets meant for soft targets. Fast jets such as the F-100 Super Sabre, F-105 Thunderchief and F-4 Phantom II proved for the most part to be ineffective for close air support because their high speed did not allow pilots enough time to get an accurate fix on ground targets and they lacked sufficient loiter time. The effective, but aging, A-1 Skyraider was the USAF's primary close air support aircraft.[6][7]A-X program
In 1966, the USAF formed the Attack Experimental (A-X) program office.[8] On 6 March 1967, the Air Force released a request for information to 21 defense contractors for the A-X. The objective was to create a design study for a low-cost attack aircraft.[5] In 1969, the Secretary of the Air Force asked Pierre Sprey to write the detailed specifications for the proposed A-X project. However, his initial involvement was kept secret because of Sprey's earlier controversial involvement in the F-X project.[5]Sprey's discussions with A-1 Skyraider pilots operating in Vietnam and analysis of the effectiveness of current aircraft used in the role indicated the ideal aircraft should have long loiter time, low-speed maneuverability, massive cannon firepower, and extreme survivability;[5] an aircraft that had the best elements of the Ilyushin Il-2, Henschel Hs 129, and Skyraider. The specifications also demanded that each aircraft cost less than $3 million.[5] Sprey required that the biography of World War II attack pilot Hans-Ulrich Rudel be read by people on the A-X program.[9]
In May 1970, the USAF issued a modified and much more detailed request for proposals (RFP) for the aircraft. The threat of Soviet armored forces and all-weather attack operations had become more serious. Now included in the requirements was that the aircraft would be designed specifically for the 30 mm cannon. The RFP also specified an aircraft with a maximum speed of 460 mph (400 kn; 740 km/h), takeoff distance of 4,000 feet (1,200 m), external load of 16,000 pounds (7,300 kg), 285-mile (460 km) mission radius, and a unit cost of US$1.4 million.[10] The A-X would be the first Air Force aircraft designed exclusively for close air support.[11]
During this time, a separate RFP was released for A-X's 30 mm cannon with requirements for a high rate of fire (4,000 round/minute) and a high muzzle velocity.[12] Six companies submitted aircraft proposals to the USAF, with Northrop and Fairchild Republic selected to build prototypes: the YA-9A and YA-10A, respectively. General Electric and Philco-Ford were selected to build and test GAU-8 cannon prototypes.[13]
The YA-10A was built in Hagerstown, Maryland and first flew on 10 May 1972. After trials and a fly-off against the YA-9A, the Air Force announced its selection of Fairchild-Republic's YA-10A on 18 January 1973 for production.[14] General Electric was selected to build the GAU-8 cannon in June 1973.[15] The YA-10 had an additional fly-off in 1974 against the Ling-Temco-Vought A-7D Corsair II, the principal Air Force attack aircraft at the time, in order to prove the need to purchase a new attack aircraft. The first production A-10 flew in October 1975, and deliveries to the Air Force commenced in March 1976. In total, 715 airplanes were produced, the last delivered in 1984.[16]
One experimental two-seat A-10 Night Adverse Weather (N/AW) version was built by converting an A-10A.[17] The N/AW was developed by Fairchild from the first Demonstration Testing and Evaluation (DT&E) A-10 for consideration by the USAF. It included a second seat for a weapons system officer responsible for electronic countermeasures (ECM), navigation and target acquisition. The N/AW version did not interest the USAF or export customers. The two-seat trainer version was ordered by the Air Force in 1981, but funding was canceled by U.S. Congress and the jet was not produced.[18] The only two-seat A-10 built now resides at Edwards Air Force Base's Flight Test Center Museum.[19]
Upgrades
The A-10 has received many upgrades over the years. Aircraft received the Pave Penny laser receiver pod beginning in 1978. It senses reflected laser radiation from a laser designator on a target for faster and more accurate target identification.[20][21][22] The A-10 began receiving an inertial navigation system in 1980.[23] Later, the Low-Altitude Safety and Targeting Enhancement (LASTE) upgrade provided computerized weapon-aiming equipment, an autopilot, and a ground-collision warning system. The A-10 is now compatible with night vision goggles for low-light operation. In 1999, aircraft began to receive Global Positioning System navigation systems and a new multi-function display.[24] Its LASTE system is being upgraded with the Integrated Flight & Fire Control Computers (IFFCC).[25]In 2005, the entire A-10 fleet also began receiving the Precision Engagement upgrades that include an improved fire control system (FCS), electronic countermeasures (ECM), and the ability to aim smart bombs. The aircraft that receive this upgrade are redesignated A-10C. The C model upgrades were to be completed in 2011.[26] 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.[11]
Modifications to provide precision weapons capability are well underway.[27] In July 2010, the USAF issued Raytheon a contract to integrate a Helmet Mounted Integrated Targeting (HMIT) system into A-10Cs.[27] 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.[28] The Gentex Corporation Scorpion "Helmet Mounted Cueing System" (HMCS) is also being evaluated.[29]
The A-10 will receive a service life extension program (SLEP) upgrade with many receiving new wings.[30] The service life of the re-winged aircraft is extended to 2040. A contract to build as many as 242 new A-10 wing sets was awarded to Boeing in June 2007.[31] Two A-10s flew in November 2011 with the new wing installed. On 4 September 2013, the Air Force awarded Boeing a follow-on contract of $212 million for 56 of the replacement wings for the A-10 Thunderbolt II, bring the number of wings on order to 173. The wings will improve mission readiness, decrease maintenance costs, and keep the type operational into 2035.[32]
In 2012, Air Combat Command requested testing of a 600-gallon external fuel tank to prolong the A-10's flight time. Flight testing of a tank was accomplished in 1997, but was never evaluated for combat requirements. The 40th Flight Test Squadron wanted to determine if the aircraft can safely reach combat flight limits while carrying the tank. An A-10C with a 600-gallon tank would expand loitering time by 45-60 minutes, pushing back tanker support. Over 30 flight tests were conducted, pushing it to greater airspeeds, Mach levels, and higher symmetrical (pulling Gs without rolling) and asymmetrical (rolling and pulling Gs) limits. Focus was on gathering data for the aircraft's handling characteristics and different aircraft load configurations to ensure flight capability. With the tank, stability in the yaw axis is slightly reduced, but there is no decrease in aircraft tracking performance.[33]
Alternate fuel tests
On 25 March 2010, an A-10 conducted the first flight of an aircraft with all engines powered by a biofuel blend. The flight, performed at Eglin Air Force Base, used a 1:1 blend of JP-8 and Camelina-based fuel.[34]On 28 June 2012, the A-10 became the first aircraft to fly using a new fuel blend derived from alcohol. It flew normally without any issues at Eglin. The fuel, known as ATJ (Alcohol-to-Jet), is cellulousic-based that can be derived using wood, paper, grass, or anything that is a cell-based material. The sugars extracted from the materials are fermented into alcohols, which are then hydro-processed into the aviation-grade kerosenes used for aviation fuel. ATJ is the third alternative fuel to be evaluated by the Air Force for fleet-wide use as a replacement for petroleum-derived JP-8 fuel. Previous types were a synthetic paraffinic kerosene derived from coal and natural gas and a bio-mass fuel derived from plant-oils and animal fats known as Hydroprocessed Renewable Jet.[35]
Other uses
The National Science Foundation has granted $11m to modify an A-10 to perform weather research for CIRPAS at the US Naval Postgraduate School,[36][37] to continue the effort after[38] the T-28 that was retired in 2005.[38][39] The A-10's armor is expected to allow it to survive the extreme meteorological conditions, such as 200 mph hailstorms, found in inclement high-altitude weather events.[37]Design
Overview
Engine exhaust passes over the aircraft's horizontal stabilizer and between the twin tails, decreasing the A-10's infrared signature and lowering the likelihood that the aircraft can be targeted by heat-seeking missiles fired from the ground. The placement of the engines behind the wings partially shields them from anti-aircraft fire.[40] The leading edge of the wing is honeycomb panel construction to provide strength with minimal weight compromise. Honeycomb panels of this type on the A-10 include the flap shrouds, elevators, rudders and other sections of the fins.[41]
The ailerons are at the far ends of the wings to gain greater rolling moment, as with many aircraft, but there are two distinguishing features. The ailerons are larger than is typical, almost 50% of the wingspan, providing improved control even at slow speeds. The aileron is also split, making it a deceleron.[43][44]
The A-10 is designed to be refueled, rearmed, and serviced with minimal equipment.[45] Also, most repairs can be done in the field.[46] 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 ordnance load, allowing the aircraft to operate from damaged airbases. If runways are damaged in an attack, the A-10 can operate from taxiways or straight roadway sections.[47]
Durability
The A-10 is exceptionally tough. Its strong airframe can survive direct hits from armor-piercing and high-explosive projectiles up to 23 mm. The aircraft has triple redundancy in its flight systems, with mechanical systems to back up double-redundant hydraulic systems. This permits pilots to fly and land when hydraulic power or part of a wing is lost. Flight without hydraulic power uses the manual reversion flight control system; this engages automatically for pitch and yaw control, and under pilot control (manual reversion switch) for roll control. In manual reversion mode, the A-10 is sufficiently controllable under favorable conditions to return to base and land, though control forces are much higher than normal. The aircraft is designed to fly with one engine, one tail, one elevator, and half of one wing missing.[49]Its self-sealing fuel tanks are protected by fire-retardant foam.[50] The A-10's main landing gear is designed so that the wheels partially protrude from their nacelles when the gear is retracted so as to make gear-up belly landings easier to control and less damaging to the aircraft's underside. Additionally, the landing gears are all hinged toward the rear of the aircraft, so if hydraulic power is lost the pilot can drop the gear and a combination of gravity and wind resistance will open and lock the gear in place.[44]
The cockpit and parts of the flight-control system are protected by 1,200 lb (540 kg) of titanium armor, referred to as a "bathtub".[51][52] The armor has been tested to withstand strikes from 23 mm cannon fire and some strikes from 57 mm rounds.[46][51] It is made up of titanium plates with thicknesses from 0.5 to 1.5 inches (13 to 38 mm) determined by a study of likely trajectories and deflection angles. This protection comes at a cost, with the armor making up almost 6% of the aircraft's empty weight. To protect the pilot from the fragmentation likely to be created from impact of a shell, any interior surface of the tub that is directly exposed to the pilot is covered by a multi-layer nylon spall shield.[50][53] In addition, the front windscreen and canopy are resistant to small arms fire.[54]
There are several reasons for the unusual location of the A-10's General Electric TF34-GE-100 turbofan engines. First, the A-10 was envisioned to fly from forward air bases, often with substandard, semi-prepared runways that present a high risk of foreign object damage to the engines. The height of the engines decreases the chance that sand or stones will be ingested. This also allows engines to keep running while the aircraft is serviced and rearmed by ground crews, reducing turn-around time. Without the limitations imposed by engines, the wings could be mounted closer to the ground, to simplify servicing and rearming.[57]
The A-10's fuel system components are protected in multiple ways. All four fuel tanks are located near the center of the aircraft, reducing the likelihood that they will be hit or have their fuel lines severed. The tanks are separate from the fuselage; thus, projectiles would need to penetrate the aircraft's skin before reaching the outer skin of the tank.[50][53] The refueling system is purged after use so that all fuel in the aircraft is protected from fire.[58] All fuel transfer lines self-seal if they are compromised; if a tank is damaged beyond its ability to self-seal, check valves prevent fuel flowing into the compromised tank. Most of the fuel system components are inside the tanks so that fuel will not be lost in case a component were to leak. Most importantly, reticulated polyurethane foam lines both the inner and outer sides of the fuel tanks, retaining debris and restricting fuel spillage in the event of damage. The other source of possible combustion, the engines, are shielded from the fuel system and the rest of the airframe by firewalls and fire extinguishing equipment. Even in the event of all four main tanks being penetrated and all contents lost, sufficient fuel is carried in two self-sealing sump tanks to allow flight for 230 miles (370 km).[50][53]
Weapons
Another commonly used weapon is the AGM-65 Maverick air-to-surface missile, with variants for electro-optical (TV-guided) or infrared targeting. The Maverick allows targets to be engaged at much greater ranges than the cannon, a safer proposition in the face of modern anti-aircraft systems. During Desert Storm, in the absence of dedicated forward-looking infrared (FLIR) cameras for night vision, the Maverick's infrared camera was used for night missions as a "poor man's FLIR".[63] Other weapons include cluster bombs and Hydra rocket pods.[64] Although the A-10 is equipped to carry laser-guided bombs, their use is relatively uncommon.[65] As of 2000, the A-10 has not been equipped with weapon control systems for accurate bombing.[20] A-10s usually fly with an ALQ-131 ECM pod under one wing and two AIM-9 Sidewinder air-to-air missiles under the other wing for self-defense.[66]
Modernization
The A-10 Precision Engagement Modification Program will update 356 A-10/OA-10s to the A-10C variant with a new flight computer, new glass cockpit displays and controls, two new 5.5-inch (140 mm) color displays with moving map function and an integrated digital stores management system.[11][27]Other funded improvements to the A-10 fleet include a new data link, the ability to employ smart weapons such as the Joint Direct Attack Munition ("JDAM") and Wind Corrected Munitions Dispenser, and the ability to carry an integrated targeting pod such as the Northrop Grumman LITENING targeting pod or the Lockheed Martin Sniper XR Advanced Targeting Pod (ATP). Also included is the Remotely Operated Video Enhanced Receiver (ROVER) to provide sensor data to personnel on the ground.[26]
Colors and markings
Since the A-10 flies low to the ground and at subsonic speed, aircraft camouflage is important to make the aircraft more difficult to see. Many different types of paint schemes have been tried. These have included a "peanut scheme" of sand, yellow and field drab; black and white colors for winter operations and a tan, green and brown mixed pattern.[67]The two most common markings applied to the A-10 have been the European I woodland camouflage scheme and a two-tone gray scheme. The European woodland scheme was designed to minimize visibility from above, as the threat from hostile fighter aircraft was felt to outweigh that from ground-fire. It uses dark green, medium green and dark gray in order to blend in with the typical European forest terrain and was used from the 1980s to the early 1990s. Following the end of the Cold War, and based on experience during the 1991 Gulf War, the air-to-air threat was no longer seen to be as important as that from ground fire, and a new color scheme known as "Compass Ghost" was chosen to minimize visibility from below. This two-tone gray scheme has darker gray color on top, with the lighter gray on the underside of the aircraft, and started to be applied from the early 1990s.[68]
Many A-10s also featured a false canopy painted in dark gray on the underside of the aircraft, just behind the gun. This form of automimicry is an attempt to confuse the enemy as to aircraft attitude and maneuver direction.[69][70] Many A-10s feature nose art, such as shark mouth or warthog head features.
Operational history
Introduction
The first unit to receive the A-10 Thunderbolt II was the 355th Tactical Training Wing, based at Davis-Monthan Air Force Base, Arizona, in March 1976. The first unit to achieve full combat-readiness was the 354th Tactical Fighter Wing at Myrtle Beach AFB, South Carolina, in 1978. Deployments of A-10As followed at bases both at home and abroad, including England AFB, Louisiana; Eielson AFB, Alaska; Osan Air Base, South Korea; and RAF Bentwaters/RAF Woodbridge, England. The 81st TFW of RAF Bentwaters/RAF Woodbridge operated rotating detachments of A-10s at four bases in Germany known as Forward Operating Locations (FOLs): Leipheim, Sembach Air Base, Nörvenich, and Ahlhorn.[71]
A-10s were initially an unwelcome addition to many in the Air Force. Most pilots switching to the A-10 did not want to because fighter pilots traditionally favored speed and appearance.[72] In 1987, many A-10s were shifted to the forward air control (FAC) role and redesignated OA-10.[73] In the FAC role the OA-10 is typically equipped with up to six pods of 2.75 inch (70 mm) Hydra rockets, usually with smoke or white phosphorus warheads used for target marking. OA-10s are physically unchanged and remain fully combat capable despite the redesignation.[74]
Gulf War and Balkans
A-10s returned to the Balkan region as part of Operation Allied Force in Kosovo beginning in March 1999.[81] In March 1999, A-10s escorted and supported search and rescue helicopters in finding a downed F-117 pilot.[82] The A-10s were deployed to support search and rescue missions, but the Warthogs began to receive more ground attack missions as the days passed. The A-10's first successful attack in Operation Allied Force happened on 6 April 1999; A-10s remained in action until combat ended in late June 1999.[83]
Afghanistan, Iraq and Libya Wars
Operation Iraqi Freedom began on 20 March 2003. Sixty OA-10/A-10 aircraft took part in early combat there.[85] United States Air Forces Central issued Operation Iraqi Freedom: By the Numbers, a declassified report about the aerial campaign in the conflict on 30 April 2003. During that initial invasion of Iraq, A-10s had a mission capable rate of 85% in the war and fired 311,597 rounds of 30 mm ammunition. A single A-10 was shot down near Baghdad International Airport by Iraqi fire late in the campaign. The A-10 also flew 32 missions in which the aircraft dropped propaganda leaflets over Iraq.[86]
A-10s flew 32 percent of combat sorties in Operation Iraqi Freedom and Operation Enduring Freedom. The sorties ranged from 27,800 to 34,500 annually between 2009 and 2012. In the first half of 2013, they flew 11,189 sorties in Afghanistan.[89]
In March 2011, six A-10s were deployed as part of Operation Odyssey Dawn, the coalition intervention in Libya. They participated in attacks on Libyan ground forces there.[90][91]
On 24 July 2013, two A-10s provided close-air support to 60 U.S. soldiers. On 23 July, a 12-vehicle convoy was conducting route clearance when the first turned over, and then was ambushed. They established an overnight base and began receiving heavy fire from a tree line the next day, pinning them behind their vehicles. Three soldiers were wounded, and CAS was called in to protect casualty evacuation efforts. Two A-10s flew over to provide a show of force and engaged when the enemy didn't break contact. The ground unit didn't have a way to confirm the enemy's position, so the unit's joint fire observer communicated the estimated location to the pilots. Once they received the general location of the enemy's position, the lead aircraft, relying only on visual references, fired two rockets to mark the area with smoke, then the wingman rolled in to shoot his cannon. Unlike normal engagements, the attackers did not run after one or two passes, but instead moved closer to the soldiers. Helicopters could not evacuate the wounded because of the volume and close proximity of enemy fire, so the convoy commander authorized the A-10 pilots to fire danger close. The aircraft flew 75 ft above the enemy's position and 50 meters parallel to friendly ground forces to conduct strafing runs. In the two hours that the A-10s provided CAS, they completed 15 gun passes firing nearly 2,300 rounds, and dropped three 500 lb bombs. Both remained on-station until all the soldiers were safe. 18 enemy bodies were found, though more were suspected. This engagement demonstrated the type of close-air support mission the A-10 Thunderbolt II was specially designed for.[92]
Proposed retirement
In 2007, the A-10 was expected to be in USAF service until 2028 and possibly later,[93] when it may be replaced by the Lockheed Martin F-35 Lightning II.[30] Critics have responded by saying that replacing the A-10 with the F-35 would be a "giant leap backwards" given the performance of the Warthog and the rising costs of the F-35 program.[94] In 2012 the Air Force briefly considered the F-35B STOVL variant for replacing the A-10 as a CAS aircraft, but concluded that the variant could not generate enough sorties to meet its needs.[95]In early 2012, the USAF proposed to disband five A-10 squadrons in its budget request, in order to lessen cuts to more versatile aircraft in a smaller future fleet.[96] Congress however delayed this action in favor of more studies on the issue.[97]
In August 2013, Congress and a National Commission on the Structure of the Air Force were still looking at the proposal to cut A-10 numbers down to 246 aircraft, as well as others. The Air Force has been trying to replace the A-10 with a multi-role fighter that can cover more area and have a wider mission set for some time. The F-35, and even the MQ-9 Reaper unmanned aerial vehicle, are seen as having the multi-role ability and modern sensors to fill the Warthog's missions of destroying vehicles and providing close-air support. A-10 pilots have been vocal about the aircraft's superiority in its field and its frequent request, sometimes by name, by ground commanders. One lesser-known function of the A-10 is escorting helicopters on combat search and rescue missions. Some believe that an A-10 that can perform this low-altitude, long-loiter time task and take ground fire is superior to an F-35 performing that job. The Thunderbolt II is armored and can take hits, while the Lightning II is not protected enough and cannot afford to be replaced if shot down. If the F-35 must do combat search and rescue, it will have a 360 degree distributed aperture infrared system that the A-10 does not. Furthermore, the two planes have different primary armaments. The F-35 relies on deploying guided bombs and missiles, which can be vulnerable to jamming, while the A-10's 30 mm cannon is immune to electronic warfare. The A-10 can destroy 14 targets per mission, while the F-35 can not. Air Force officials have stated publicly that the F-35 will not duplicate the A-10's missions, but they do need a multi-role aircraft and it has a longer range. Air Combat Command has said it should not be about which newer weapon systems must replicate the exact capabilities of older systems, but how many new systems will be needed to address future capabilities. The Air Force has not ruled out replacing the A-10 with another light attack aircraft to maintain numbers and mass firepower with the advantage of being able to integrate next-generation sensors.[89]
As part of the U.S. Air Force's FY 2015 budget, the service is considering retiring the entire A-10 Thunderbolt II fleet and other single-mission aircraft to prioritize multi-mission aircraft and keep future procurements on track. While the service has previously considered cutting squadrons, cutting an entire fleet with its infrastructure support is seen as the only way to gain major savings.[98] The Pentagon and active Air Force have tried to retire the single-mission platform for years. While Congressional resistance has previously saved the A-10, budget realities may finally defeat the aircraft. Members of the Air National Guard and Air Force Reserve argue that moving A-10s from the active Air Force use to their control completely would achieve savings while still keeping them in the Air Force inventory. Half of the fleet is already under National Guard control. The U.S. Army has expressed their dissatisfaction with the process of replacing the aircraft they call on for close-air support. The Army has shown interest in obtaining A-10 jets themselves if the Air Force retires them.[99][100]
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