Power was derived from a pair of high-mounted General Electric TF34-GE-100 series turbofans. These are rated to just 9,065lb of thrust each and kept the A-10 a subsonic performer incapable of supersonic flight. However, for the CAS role, supersonic speed was a non-essential component. In fact, the A-10 came in over 2,000lbs heavier than initially intended. The added weight was simply written off by the USAF, believing the slight decrease in speed was manageable in the CAS role. The engines were mounted high to keep them as far away from ground fire as possible while also keeping them clear of ingesting foreign objects when operating from unprepared airfields. The A-10 can operate with one complete engine being lost to action. Each engine nacelle was angled up ever so slightly to 9 degrees to bring the combined thrust outflow more in line with the airframe's center of gravity. The all-important Auxiliary Power Unit (APU) was fitted in the fuselage near the engines, its exhaust port always marking the portside engine nacelle with a streak of black soot.
The empennage was dominated by the twin vertical fin tail design, each fin holding its own rudder control. The horizontal tailplane was set low on the fuselage and fitted the vertical fins as outward from centerline as possible. Each tailfin sported slight sweep along the leading edge and no sweep along the trailing edge. The fins sat high above the stabilizer, the stabilizer itself also working to reduce the amount of visible heat exhaust being generated by each turbofan engine. This helped to make tracking and lock-on by ground-based radar somewhat tougher.
Listed performance for the A-10A included a top speed of 439 miles per hour with a cruise speed of 340 miles per hour and a never-exceed speed of 518 miles per hour. Stall speed was 138 miles per hour. Combat radius was nearly 300 miles depending on payload and mission type. Ferry range was a reported 2,580 miles. Service ceiling was 45,000 feet with a rate-of-climb equal to 6,000 feet per minute.
The GAU-8/A 30mm Cannon
The GAU-8/A was the heart and soul of the A-10 Thunderbolt weapon system. This massive 679-pound seven-barrel rotating cannon operated on the relatively simple Gatling principle made popular by American inventor Richard J. Gatling in the time of the American Civil War. The general principle held that a set of rotating barrels could cool themselves faster during the firing action. This allowed for an exceedingly high rate-of-fire without the overheating problems common to a single barrel repeating weapon. General Electric designed and developed the GAU-8/A "Avenger" system used in the A-10 Thunderbolt II, an armament from which the A-10 was essentially built around. In true A-10 speak, the GAU-8/A is actually part of the 4,200lb A/A49E-6 weapons system when detailed as a collective unit.
Some interesting notes compliment the GAU-8/A. Its seven-barrel function means that the entire barrel system is slightly offset to the left to keep the firing barrel aligned with the fuselage centerline. The weapon system, as a whole, is also quite large (including the ammunition drum). The size is such that a picture was released during development showing the GAU-8/A dwarfing the overall size of a Volkswagen Beetle. In fact, the GAU-8/A is closer to the size of a full-size family sedan when measured end to end. The photograph quickly made the runs of various magazines and helped to promote the intimidating aura of the Avenger system.
Operation of the GAU-8/A is controlled via a gearbox with two separately-controlled hydraulic drive motors. The weapon sits under the cockpit floor and shares space with the nose landing gear. The main barrel assembly runs from under the titanium tub and protrudes just passed the curved nose assembly. The barrels are attached to a transfer unit which is backed by a hydraulic drive system. The whole unit is connected to the all-important ammunition drum which sits on its long side behind the cockpit. A double-layer conveyor belt system feeds fresh 30mm projectiles to the barrels while removing spent shell casings in return. Spent shell casings are not jettisoned from the A-10 upon firing, as is common with most other military aircraft, reducing the chance that any spent casings will be ingested into the engines. Exhaust ports for the GAU-8/A are located along the underside and sides of the forward fuselage. A gun nozzle seal protects the protruding section of barrels at the front. The ammunition loading door is under and aft of the cockpit along the underside of the fuselage. A fresh ammunition drum can be installed by trained technicians in as little as thirteen minutes. The drum system is attended to by a specialized four-wheeled ammunition loading assembly cart - the Syn-Tech GFU-7/E - the only specialized piece of equipment that the A-10 needs at a forward operating base. An ammunition drum is typically fielded with 1,174 rounds of 30mm projectiles.
The A-10 GAU-8/A cannon utilizes large 30mm projectiles in three major forms, each full projectile measuring in at an impressive 11.4 inches in length. The projectile is primarily made up of the cartridge case, this making up roughly half of the projectiles length, with a tapered upper portion ultimately concluding in the pointed nose cap. Available projectile types include the PGU-13/B High-Explosive Incendiary (HEI), the PGU-14/B Armor-Piercing Incendiary (API) and the PGU-15/B Target Practice (TP) rounds. Typically, ammunition is loaded in what is known as a "Combat Mix" - an HEI round followed by five API rounds. The HEI round doubles as an aiming tracer round for the pilot. The TP round, though technically a trainer projectile, can also be used against lightly skinned vehicles and forms the least expensive munition for the 30mm cannon. The API weighs in at 1.6lbs while the HEI and TP rounds are both 1.47lbs.
The API round is a depleted uranium projectile and is proven to penetrate any modern battlefield tank in operation, even those further protected by "reactive armor" panels. The HEI round is adept at killing lightly-armored vehicles by its deadly fragmentation "spray" and can also trigger fires some feet away from the target zone itself. While disabling a vehicle, the HEI round is capable of further maiming or killing the occupants. The use of depleted uranium has long held some controversy with watch-dog groups, citing the after-effects the material may have on civilian health.
The GAU-8/A is afforded two rates of fire that allow for settings of approximately 2,100 or 4,200 rounds per minute. Aiming of the gun is through a reticle in the HUD with each barrel sighted and aligned by grounds crew prior to firing. Firing is generally in few second intervals so the rate-of-fire is more accurately reported between 30 and 70 rounds per minute. The gun computer calculates ballistics based on the ammunition type selected by the operator. When fired, the 30mm cannon produces a noticeable cloud of gas that screens some of the forward portion of the fuselage for a brief moment. The velocity of each 30mm round is such that there is little projectile drift once it leaves the barrel and the A-10 aircraft actually slows a few knots of speed in the firing action. The GAU-8/A can be used on slow, low-flying aircraft such as helicopters and was credited with two such kills in Operation Desert Storm. The ammunition for the gun is counted through a conventional counter on the cockpit instrument panel, decrementing the count by a value of ten.
Testing of the gun, as mated to the actual A-10 airframe, began in September of 1974. Though the results of the ammunition on test battlefield tanks proved excellent, it was found that an inordinate amount of dangerous explosive gasses was generated in the firing action, resulting in an external fireball being created ahead of the pilot. The projectile propellant was changed but this resulted in the loss of one of a preproduction aircraft to a flameout as residue from the propellant was now being ingested into the engines. Enter the Battelle device...
The Battelle Device
The Battelle device was developed by Battelle Laboratories as a gas diverter to be fitted to the barrel muzzles of the GAU-8/A. It was a relatively cheap fix but it was soon found to contribute to unacceptable stress fractures of the airframe along various locations of the forward fuselage. As such, the Battelle device was dropped from consideration. Instead, the engines were fitted with a system that maintained continuous ignition for every moment that the 30mm gun was to be fired and for a short time after the trigger was depressed. Additionally, maintenance requirements now stipulated that engines were to be washed once for every 1,000 rounds fired. In effect, the ingestion of the main gun residue into each engine was never fully solved for the life of the A-10 Thunderbolt II, a threat that the modern A-10 pilot faces even today. As an aside, the GAU-8/As rate-of-fire was temporarily revised to 3,900 rounds per minute in preparation for the Battelle device.
The A-10 makes stellar use of the eleven hardpoints allotted to its layout. One is located along the fuselage centerline with two more held to either side of the fuselage undersides. There is another hardpoint inboard of each main landing gear sponson and three more are fitted outboard. Hardpoints are numbered from 1 to 11 when viewing the aircraft in the forward profile (right wingtip to left wingtip). The weapon release sequence - that is, the sequence in which each pylon drops its payload - is as follows: 8, 4, 11, 1, 10, 2, 9, 3, 7 and 5. Hardpoint number six is always reserved for specialized pods (a 600-gallon fuel tank or a pilot's travel pod) and is not wired to drop ordnance. Note that the sequence essentially begins inside of the wheel sponsons, then jumps to an outward-to-inward fashion along the wings, and concludes with the underside fuselage pylons. Also note that each respective pylon also drops their munitions in a certain order all their own so the aforementioned sequence can vary with a full weapons payload (i.e. triple Maverick mountings for instance). This maintains a healthy weight load across the airframe as the ordnance load itself changes.
Some general pylon notes include munition-loading restrictions along hardpoints 1 and 11 as well as 5 and 7. No munitions may be carried on 5 and 7 while 1 and 11 are limited by way of only using drop munitions (no forward firing missiles allowed). Hardpoints 4 and 8 are "plumbed" to accept 600-gallon fuel tanks. The fuel tanks are the same as those used by the General Dynamics F-111 Aardvark swing-wing bomber but most A-10 pictures rarely showcase the extra fuel load. An outboard hardpoint is also generally reserved for the carrying of jammer pods in modern A-10 functions.
The AGM-65 Maverick Air-to-Ground Missile
The A-10 Thunderbolt II is cleared to carry and launch a variety of ordnance including guided surface-to-surface missiles, air-to-air missiles, laser-guided bombs and dumb bombs of conventional origins. Aside from the 30mm cannon, the AGM-65 remains the Thunderbolt's tank-killing system. This family of missiles is proven and comes in a variety of warhead and seeker types. There are six primary forms designated as the AGM-65A, AGM-65B, AGM-65D, AGM-65F, AGM-65G and the AGM-65E. The AGM-65A and AGM-65B are TV-guided missiles fitted with shaped-charge, 125lb warheads. They are differentiated by the B-model's magnified scene, increasing its target acquisition range. Both are fire-and-forget systems with proven performance in daytime actions.
The AGM-65D, F- and G-Mavericks feature infra-red guidance systems - imaging IR with a digital tracker. The D-model shares the warheads of the A- and B-models. The F- and G-models use a 300lb kinetic energy penetrator warhead. The D-model enjoys a day/night attack capability while the F- and G-models are cleared for use against surface ships, a task generally reserved for dedicated anti-ship missile systems such as the Harpoon series.
The AGM-65E Maverick is a laser-guided munition with a 300lb kinetic energy penetrator warhead. Guidance is passive laser with a digital tracker but can tackle laser-designated targets in both day and night actions.
Launch and Drop Munitions
Aside from the Maverick, A-10 pilots enjoy a healthy stable of conventional launch and drop munitions. The former is made up of traditional LAU-10 series rocket pods for use against structures and soft-skinned targets. Rocket pods are carried on stations 3 and 9. The latter comes in the shape of the family of drop bombs (also called "dumb" bombs). These are formed by the 500lb Mk 82 and the larger 2,000lb Mk 84 bombs. When fitted with retarding glide fins, these bombs are known as the Mk 82SE and Mk 84SE "Snakeye" bombs. The A-10 is also cleared to drop laser-guided bombs though, unlike other aircraft in the US inventory, the early Thunderbolts could not "self-designate" - that is, mark her own targets and launch their guided bombs. She instead relied on friendly ground personnel to "laze" a target for her before launching. Standard laser-guided bombs for the A-10 include the GBU-12 500lb bomb and the GBU-10 2,000lb bomb. Regardless of the "laser-guided" designation, these are nothing more than slightly modified forms of their dumb cousins, made more lethal by their guided accuracy by way of field modification kits. So long as the laser designator stays trained on the target, the guided bomb will follow its flight path along the reflected energy generated by the ground laser to the relative target location.
Other weapons included the Mk 77 incendiary bomb, the BLU and CBU series cluster bombs, Paveway LGBs, Joint Direct Attack Munitions and Wind Corrected Munitions Dispensers. Targeting pods for the A-10 now include the LITENING system (specifically the A-10C) and allow the A-10 to "self-designate" its missile and laser-guided targets without requiring ground forces to do it.
Aside from her design and armoring, the A-10 Warthog stays alive through a series of built-in functions. Perhaps most important is use of an Electronic CounterMeasures (ECM) pod - most likely the ALQ-131 ECM pod (also the AN/ALQ-184 ECM). The pod is usually fitted on an outboard wing pylon. These pods serve to jam incoming enemy radar transmissions and attempt to deflect lock-on by ground based radar installations and systems. In addition to the ECM pod, A-10s make use of conventional chaff (interference foil strips) and flare (deflective heat source) launchers to counter the tracking of ground-based missiles that have been launched. These dispensers are mounted at the wing tips as well as just behind each wheel sponson. The SUU-42A/A flares/Infrared decoy and chaff dispenser pod is also optional.
The AIM-9 Sidewinder forms the other portion of the Thunderbolt II self-defense toolbox. These missile systems are essentially as those found on other American fighter aircraft and provide a healthy and lethal defense against enemy helicopters and other aircraft. The AIM-9 is a short-ranged weapon and only two are generally ever carried on the A-10, usually on the wing opposite the pylon holding the ECM pod, though an additional pair can be mounted in the opposite placement in place of the ECM pod itself. One Sidewinder can be carried on the standard A-10 pylon though the LAU-114 launcher rail allows for a pair to be affixed and launched as normal.
The 'Hawg in Europe
Warthog crews and their mounts were stationed in Europe, the site of what was to become the battlefield for which the system was always groomed for, and became a part of the USAF's largest combat wing there. The Thunderbolt maintained a healthy operational range and could reach places within East Germany and some layers beyond when called to action. There were four major Forward Operating Locations (FOLs) and six in total. The four were located at Ahlhorn, Noervenich, Sembach and Leipheim in West Germany. A-10 pilots could easily have been called to action to help defend far-off places like Italy and Norway if need be as well. Pilots cycled in and out of service within this region to learn the layout of the land, get exposure to flying in the regional elements and commit to memory the battleplan should a Soviet ground assault ensue. As the initial wave of Soviet strikes would most likely target airfields, the A-10 was also tested on highways and unprepared positions to fully "stretch" her legs. Some 72 A-10 Thunderbolt IIs could be made available in the event of a Soviet invasion.
The A-10 would have worked in conjunction with the US Army's AH-64 Apache in the anti-tank role, assaulting Soviet armored columns as they made their way to key objectives. With the end of the Cold War, many A-10 Thunderbolts were brought back state side with talks of retiring the old girl. Only the 52nd FW based out of Spangdahlem Air Base in Germany was to remain.
A-10As in Europe were painted over in a European woodland camouflage scheme using a combination of greens and dark grays, the thought being they would mesh well with the surrounding terrain.
Warthogs in Desert Storm
Despite its appearance in the 1970s, Thunderbolt II pilots had to wait sometime before being able to prove their machine in actual combat. That came along in the form of the 1991 Gulf War - through Operation Desert Storm - versus Saddam Hussein's "4th largest army" in the world. Hussein moved his ground forces from Iraq into Kuwait in an attempt to capture a large portion of the regions oil production. A United Nations effort ousted his army back onto Iraq soil in the first true "digital" war, a war that brought about the first combat actions for the M1 Abrams and the F-117 Stealth Fighter. By the end of it all, Hussein's army was reduced to a rabble of retreating (or surrendering) personnel with little in the way of discipline. This was due, in some part, to the actions of the A-10 and her crews.
Some 144 A-10A and OA-10A aircraft were sent to the region from the 23rd TFW(Provisional) and 354th TFW(Provisional) making up five squadrons operating out of King Fahd International Airport in Northeast Saudi Arabia (74th TFS formed the dedicated night wing). The first recorded combat missions by an A-10 occurred on January 15th, 1991. Targets included all sorts of manner made up of trucks, tanks, armored personnel carriers, vehicles, bunkers, radar installations, artillery emplacements, missile batteries and grounded aircraft. In the end, the A-10 accounted for over 15% of all coalition sorties, totaling 8,755 all their own. Tanks proved the major target and no Soviet-made armor in Iraqi hands was safe from the smiling, sharp-toothed Warthogs, essentially making "aces" out of her pilots (though these kills achieved against tanks, and thusly not "proper" aces).
The A-10 proved exceptional in her role. She showcased the long loitering times she was required to have and her armament delivery capabilities were second to none. 'Hogs were able to deliver their payload against multiple targets, return to friendly forward bases and reload, only to head out and deliver their payload once more. Her durability and ease-of-maintenance was also worth noting. Many-a-report recalled whole sections of fuselage or wing surface area being peppered with enemy flak with the A-10 pilot returning safely home. Moreso, large sections of wing and tail surfaces could be lost and still keep the aircraft fly-worthy. In all, the A-10 accounted for the destruction of 987 Iraqi tanks and 500 APCs. 926 artillery systems and 1,106 trucks also fell victim to the might of the Warthog.
In addition to traditional sortie runs against vehicles, the A-10 was called upon to support special operations forces on the ground in the Close-Air Support role. She was also given instruction to utilize her loitering capabilities in the location and possible destruction of SCUD missile sites when available. Other non-conventional targets soon were brought into the HUD of the A-10 and included supply depots and arm stores. The beauty of the A-10 was that she could assault all of these targets by cannon, bomb or missile as needed.
All was not rosy for the A-10 crews however. Their mission set included some of the most dangerous low-level runs imaginable where hostile AAA (Anti-Aircraft Artillery) could quickly open up and spear the internal workings of the 'Hog. Regardless of such damage, an A-10 could be repaired and back in the air in a matter of days. Nearly half of the 144 fielded Thunderbolt's would receive some level of damage during the war. Six Thunderbolts were lost to enemy SAMs (Surface-to-Air Missile) systems while a further 14 were damaged.
In all, the Persian Gulf War served as a suitable test ground to usher in the weapons of tomorrow. Saddam Hussein maintained a large land army at the time, though much of his equipment was adequate at best and his men's training below average for the most part. The result was a lopsided coalition victory that showcased the strengths and weaknesses of the respective armies at play and brought about changes to both technology and doctrine in the years following. The A-10, once on the cusp of her twilight years, had proven her mettle and made a bona fide star of the ugly aircraft with her unique brand of pilots.
Perhaps worth noting is that the A-10 was credited with two air kills during the war, both at the hands of the GAU-8/A cannon and against a BO-105 and Mil Mi-8 helicopter in different instances on February 6th and February 15th, 1991 respectively (different pilots as well). It is interesting that the AIM-9 Sidewinder did not record a kill in the whole of the war with just three being fired on accident. Thunderbolts deployed to the Persian Gulf were also sans any night attack capability. Pilots flying at night generally relied on the FLIR of their AGM-65D IIR Maverick systems for the task - this method not endorsed by the USAF.
The Two-Seat Night-Attack Warthog
Though developed but never produced, there did exist a two-seat dedicated night attack version of the A-10A. The two-seater was designated in the developmental YA-10B fashion and would have gone on to become the "A-10B" in production. Using a production A-10A as the conversion model, a second seat was added in tandem fashion, affording the rear crewmember a view over the pilots seatback. The cockpit was redundant for the most part, mimicking the controls of the forward position and the only component differentiating the two was the lack of a HUDs element in the rear position. Each cockpit was given a curved canopy that opened to the starboard side with a "A" frame separating the two assemblies - this would have become a rear-hinged unit in production models. The 30mm nose cannon was retained. To offset the added weight and position of the second cockpit in relation to airflow and stability, the vertical tail fins were heightened by 20 inches each (later shortened by 12-inches). The YA-10B was fitted with two distinct recce pods, the AAR-42 FLIR and the WX-50 ground-mapping radar. The former was fitted to the starboard side fuselage hardpoint and the latter to the port side fuselage hardpoint. Other specialized components were fitted and still others were tested for possible use. All of these additions increased the base A-10A airframe some 2,000lbs. Interestingly, the important titanium tub armor protection was not extended to the rear crewmember, this despite the decided weight gain of the new design.
Republic put up some of the development money and the rest was handled by the USAF. Low priority to the project meant that the aircraft lingered in development for some time. Republic attempted to market the two-seat A-10B as not only a dedicated night-strike platform but also a combat-capable two-seat trainer conversion model. Additionally, the A-10B could be used in the air defense suppression role thanks to its payload capabilities and loiter times. Another effort marketed the new A-10B as an anti-ship maritime strike aircraft. Alas, the A-10B never materialized beyond the single YA-10B prototype. The USAF rebuffed the new design, as did interested foreign parties, and the sole YA-10 was handed over to the Air Force Flight Test Center Museum at Edwards AFB in California.
Training for A-10 pilots was handled simply by having an instructor in another A-10A accompanying the primary student A-10A pilot for his/her first few flights.
The Base A-10A was modified in 1987 to create the airborne Forward Air Control (FAC) observation platform in the OA-10A. The USAF was desiring additional F-15 Eagle and F-16 Fighting Falcons in their Cold War stable and developed a scheme to acquire them by labeling the A-10A as passed their prime, assigning them to the inglorious role of Forward Air Control (FAC) under the designation of "OA-10A". Modified F-16 Fighting Falcons would now take the place of the A-10A in the CAS role. Essentially, the OA-10A differed in no way from the attack A-10A except in mission specification. The OA-10A eventually replaced the highly-effective but aged Rockwell OV-10 Broncos in the FAC role. Despite the designation, the OA-10A remains a fully combat-capable airframe. In October of 1987, the 602nd Air Control Wing out of Davis-Monthan AFB began taking delivery of the OA-10A. Creation of the OA-10A also brought about two new Air National Guard groups in 1990 and 1991, these becoming the 110th TFS out of Michigan and the 11th TFS out of Pennsylvania.
Upgrading the Hawg
The A-10 received some much needed attention in the 1980s. The system was heading towards a mid-life crisis and the LASTE (Low-Altitude Safety and Targeting Enhancement) program was put into effect. This program would substantially upgrade the core avionics package of the A-10 with ground collision, an F-16 style computerized weapons delivery system, revised HUD for air-to-air work, improved software support and (finally) the addition of an autopilot system. The program, though developed and cleared, did not go into effect until after the 1991 Persian Gulf War. Later improvements also allowed use of night vision goggles by the pilot, no longer counteracted by the light emitted from the A-10 instrument panel at night. Night vision upgrades were completed in 1997. New INS and GPS compatibility occurred in the 1990s as well.
Blasphemy: The Warthog in Foreign Hands
The Thunderbolt was not always going to be an American only product. It was almost inevitable that an ally would come calling for such a potent tank-killing system and Turkey nearly became a major operator of the time (Israel, Egypt and South Korea were also contenders). In 1993, Turkey shown interest in obtaining fifty examples while American warplanners were beginning to move away from the A-10. However, the US State Department intervened and killed the deal altogether, citing an objection to exporting the depleted uranium projectiles needed in the GAU-8/A cannon. Cost escalations on Turkey's side also left the deal in limbo and the sale was never finalized.
The Here and Now: The A-10C
Lockheed Martin now sustains the A-10 Thunderbolt II and supports software and other upgrades. Some 356 A-10 and OA-10 Thunderbolt IIs are scheduled or modernization through the incremental A-10 Precision Engagement Modification Program. The cockpit will feature some F-16 styling with two 5.5-inch color displays, a moving map display and a digital stores management system. The changes have therefore created a new variant within the A-10 family known under the designation of "A-10C". A-10Cs have already been deployed to Iraq in 2007 as part of the 104th Fighter Squadron, ANG out of Maryland. Many operational A-10 squadrons run a mish-mash of A-10A strike and OA-10A observation models, covering a mix of battlefield sorties should the need arise including that of Search & Rescue (SAR) of fallen comrades, FAC and CAS.
As of this writing, the USAF intends on keeping its fleet of A-10 Thunderbolts optimistically flying up to 2028 with potential replacement coming in the form of the highly-advanced Lockheed F-35 Lightning II. A-10s have also been featured in the War in Afghanistan, responding in the CAS role as needed. To date, some twenty A-10 squadrons exist with the USAF, ANG and the AFRC. Seven hundred fifteen total Thunderbolt IIs were eventually delivered at a unit cost of $11.7 million dollars apiece. Two were YA-10 prototypes while six became YA-10A preproduction evaluation aircraft. The rest were production A-10A and conversion OA-10A and A-10C models.
After the end of the Cold War (and post-Desert Storm), the European camouflage of the A-10A gave wave to a more subtle and generic dark-gray-on-light-gray paint scheme. Sometimes false canopies are painted along her underside to confuse enemy ground parties. Nose art, though not officially accepted by the USAF, was utilized to good effect in the Gulf War by A-10 crews.
The phrase "Go Ugly Early" is a motto associated with the A-10 Warthog and is generally a call by ground troops requiring the lethal force of the A-10 early in a battle.