The A-10

During the First Gulf War an aircraft previously unwanted became the most valuable member of the American arsenal- the Fairchild Republic Thunderbolt II. It's a gun that they decided to make fly. The aircraft was built around the gun, not the other way round. The gun has a rate of fire of 2,100/min if using one engine (gun engine) or 4,200/min if using two engines. That's between 35 & 70 rounds per second.

Due to it's success in the First Gulf War, the A-10 Warthog is one of the most famous military aircraft in the world. During the war "Hog" pilot's flew 8,100 sorties, destroyed over half the Iraqi armour & artillery, assisted in search & rescue missions, hunted Scud's & often operated under cover of darkness at night.

The aeroplanes durability & the perseverance of airforce pilots enabled the Warthog to operate with a mission capability of a staggering 96% & as a testament to it's toughness only 6 of the 144 Warthogs deployed to the Gulf were lost.

The Warthog is one of the most formidable aeroplanes in the history of aviation. Although this remarkable aeroplane can carry 16,000 lbs (7257.6 kilo's) of mixed ordnance it is the massive 30mm Avenger cannon which places the Warthog in a class of it's own. The Avenger can fire up to 70 rounds per second & is the largest gun ever put into a fighter plane. It's capable of knocking out tanks, trains, boats or anything else. With an impressive mixture of agility, toughness & phenomenal fire power the A-10 is one of the worlds great planes.

First flight of a production A-10 (73-1664) was on 15th February 1975 . Tactical Air Command accepted the first A-10A on 30th March, 1976. The first production A-10's were delivered to the 333rd Tactical Fighter Training Squadron (TFTS), 364th Tactical Training Wing (TTW) at Davis-Monthan AFB, Arizona.

The first operational A-10's joined the US arsenal when introduced to the 354th Tactical Fighter Wing at Myrtle Beach Air Force Base, South Carolina in 1977 (Myrtle Beach AFB opened in 1941, closed 31st March 1993, and demolition began in September 2000). A combination of Myrtle Beach Air Force Base & a brand new airframe made it the most desirable assignment in the United States Air Force. There was no shortage of volunteer's for this aeroplane.

Upon it's introduction with the US Air Force it was equipped with only three radio's & a navigational receiver. There were no on board computer's to help guide the aeroplane or help with the weapons systems. Quite a bit of money has been spent since those early days in terms of retrofitting the A-10. The Hog now has a very capable air to ground computing system that helps the pilot aim the weapons including the 30mm cannon & bombs. An A-10 won the air force's biennial gunnery competition in 1991. It belonged to the 175th TACTICAL FIGHTER GROUP of the Maryland Air National Guard.

In January of 1973 the Fairchild Republic Corporation unveiled the aeroplane the air force & the army desperately wanted, the A-10 Thunderbolt II. It was ugly but it was exactly what the military needed. The conflict in Viet Nam had painfully illustrated the need for a new aircraft to handle the difficult task of close air support, a role the A-10 was purpose built to perform. This is a dangerous task to fulfil. The A-10 must loiter around the battle while providing support for ground forces & destroying enemy vehicles, tanks & artillery. This function must be performed at low altitudes under heavy enemy fire.

The A-10 evolved from lesson's learned in Viet Nam but it was in reality designed to provide close air support in Europe. The A-10 with it's tank killing ability stood as an integral part of NATO strategy to match the threat of Soviet tanks threatening Western Europe.

The first overseas unit to equip with the A-10A was the 81st Tactical Fighter Wing based at RAF Bentwaters and RAF Woodbridge, in the United Kingdom. The 81st TFW was an unusually large unit composed of 6 squadrons -- 108 total aircraft at full strength. The A-10's of the 81st TFW were in Europe primarily to support NATO operations against potential enemy armour invasions of central and Southern Europe. Many A-10's of the 81 TFW were deployed to forward operating areas (i.e. Sembach AB, Germany) throughout Europe to provide a quick reaction anti-armour weapon close to potential battle fronts.

The first use of the A-10A in combat was in January 1991 with the start of Operation Desert Storm.

The original Thunderbolt was the legendary P-47 Thunderbolt from WWII which was also made by Fairchild Republic. Thus the A-10 is called Thunderbolt II in honour of it's close air support ancestor.

The original Hogs were the F-84's, nick named as such because on hot days the aeroplane would often struggle to get off the ground. Around 3,300 of the original Hogs were built serving from the 1950's into the 60's.

Fairchild Republic continued to upgrade the Hog & in 1952 they produced a swept wing version known as the F84F Thunderstreak. The legacy of the Hogs continued with the advent of the Superhog. Capable of 685 mph (1102.17 k/ph) & a range of 1650 miles (2654.9 kilometers) it became an integral part of the US Air Force. Fairchild Republic built around 2,700 Superhogs.

The Warthog's arsenal includes the GAU-8/A 30mm Gatling Gun which has a muzzle velocity of 3,240 ft/s (988 m/s) if firing armour piercing incendiary rounds (API) or 3,400-3,450 ft/s (1,036-1,052 m/s) if firing general-purpose shells loaded with high-explosive/incendiary (HEI) compound. The magazine capacity is 1,350 rounds which weight 1.6 pounds each (0.726 kilo's) or uranium-depleted 0.43kg each (0.95 pounds) API rounds & are approximately 11.25 inches long (285.75 millimeters). The rate of fire is 2,100/min if using one engine (gun not aircraft engine) or 4,200/min if using two engines with a range of 6,500m (6½ km or 4 miles). That's between 35 & 70 rounds per second. The pilot can select a firing rate of 2,100 or 4,200 rounds per minute.

Almost all the space forward of the wings is devoted to the gun system. The cockpit floorboards are mounting surfaces for some of the gun structure & with the exception of the electronic controls & the battery almost all of the aircraft is the gun.

Early in the design stage of the A-10 Thunderbolt II Fairchild Republic opted for a 30mm Gatling gun as the ideal weapon of choice but the sheer size of the GAU-8/A cannon presented a design problem. The only solution was to design the plane around the gun! Fully loaded the gun weighs 4,0291b (1,830kg).

The projectile is exceedingly lethal. With the armour piercing incendiary rounds a very small slug of depleted uranium is actually what is delivered on target. It strikes the target with almost 12 times the kinetic energy of it's predecessor the 20 mm round even though it's only 50% larger in linear dimension it has 12 times the kinetic energy of the target.

The tremendous recoil force of the gun lead to it's positioning slightly off set to port so that the firing barrel is exactly on the centre line. This avoids the problem of asymmetric recoil force. The gun produces as much recoil as the engines produce in forward thrust which means theoretically if you had sufficient ammunition & held the trigger down long enough the aeroplane would come to a complete stop because the gun would win the tug-of-war. The Warthogs twin General Electric TF34-GE-100 turbofans produce 9,060 lb (2 x 40.3 kN) of thrust each & the recoil force of the 30mm cannon is 9,000 lb (40 kN).

Due to the recoil force of the gun it is fired in short bursts of about two seconds. This also avoids ammunition wastage & barrel overheating.

Hughes Tool Company was awarded a development contract for the GAU-9 to be used in case the GAU-8 programme failed. The GAU-9 was a license-built version of the Swiss Oerlikon 304RF 30 mm cannon. The GAU-9 was tested against the GAU-8 in the spring of 1973 but was inferior to the "Avenger" so development was halted on the GAU-9.

The 30mm GAU-8/A cannon is not the only weapon the Warthog has at it's disposal. The plane can carry up to 16,000 lbs (7257.6 kilo's) of releasable external stores. This is four times the amount a World War II B-17 could carry. The aircraft is also equipped with a state of the art delivery system called CCIP or Constantly Computed Impact Point. This allows the delivery of dumb bombs with pin point precision.

The typical combat loadout of the aeroplane would included the 30mm cannon, 1,350 rounds of 30mm ammunition, six bombs, an assortment of Maverick missiles & the Aim 9 Sidewinder air to air missile for self defence.

Reinforced with nearly 3,000 lbs (1360.8 kilo's) of titanium armour plating, the Warthog can survive direct hits from armour piercing & high explosive projectiles of up to 23 mm. Twelve hundred pounds (544.32 kilo's) of titanium surrounds the cockpit, enveloping the pilot in what is referred to as the titanium bathtub. This bathtub of 1½ inch (38.1 millimeters) armour gives Hog pilot's added security as they undertake their dangerous missions.

The Warthogs toughness is compounded by a number of system & structural redundancies. The duel redundancy of the hydraulic flight control systems is also backed up by a manual system. This allows Hog pilot's to fly & land even if hydraulic power is lost. The Hog's extremely high mission capability rate during the First Gulf War directly resulted from a design dedicated to ensuring the plane could be serviced & operated from bases with limited facilities close to the battlefield.

Many doubted if the Warthog could adapt to the duel missions of the post cold war era, but the Warthog rose to the challenge & during Gulf War I gave outstanding performance in a variety of rolls. Despite flying only 30% of the sorties the A-10 was responsible for just over 50% of the confirmed bomb damage with the loss of only 6 planes & 2 pilots. Given the heavy use of the aeroplane it did not take long for the Iraqis to become all too familiar with the "Warthog".

Once deemed too slow, too simple & too ugly to be of much value, the A-10 Thunderbolt II "Warthog" now stands as one of the worlds undeniable great planes.

The A-10 has been criticized for its minimal avionics fit. It was originally intended purely for close air support, for which it was felt that complex electronics would be unnecessary (and would have an undesirable effect on serviceability and cost). Initial fit provided basic communications, a radar-warning system, and TACAN navigation, early aircraft lacking even an autopilot. As USAF emphasis shifted towards the anti-armour role, presumably in a conflict with the Warsaw Pact forces in Western Europe , where weather is frequently poor, there was pressure for improved sensors and electronics. Fairchild-Republic offered a two-seat Night and Adverse Weather (NAW) variant beginning in 1977, but it was not adopted. Aircraft were eventually upgraded with inertial navigation and a Pave Penny laser sensor (marked target seeker) pod that allowed the pilot to detect laser energy for PID (Positive Identification) of an illuminated target. The Pave Penny is a passive seeker and cannot self-designate a target for a Laser Guided Bomb (LGB). However, the A-10 can drop LGBs with the help of another aircraft (Buddy-Lase) or, when equipped with a targeting pod (Self-Lase).

The A-10 also initially lacked systems to compute target range or impact points, greatly limiting its ability to deliver weapons other than cannon and rocket fire (in direct, visual-range attacks) or the self-guided AGM-65 Maverick missile, whose own sensors displayed imagery in the A-10's cockpit. Often times this small monitor would provide the only source of imagery for missions that took place in dark environments. Much later in the "Warthog's" career, the Low-Altitude Safety and Targeting Enhancement (LASTE) upgrade provided computerized weapon-aiming equipment, an autopilot, and ground-collision warning system. The A-10 is now compatible with night-vision goggles for low-light operation. In 1999, aircraft began to be given Global Positioning System navigation systems.

With the end of the Cold War and the decreasing likelihood of a conflict between the United States and a Soviet style army (in other words, a heavily mechanized force) the continued need for the tank-busting A-10 has been questioned. Several efforts to withdraw the A-10 Thunderbolt from active service have been made over the years. However in recent conflicts, such as the 2001 war in Afghanistan and the 2003 invasion of Iraq the A-10 proved useful as it can destroy any vehicle it can locate.

The A-10 is scheduled to stay in service with the USAF until 2028, when it may be replaced by the F-35 (Joint Strike Fighter). Beginning in 2005 the entire A-10 fleet was upgraded to the "C" model that will include improved FCS (fire control system), ECM (electronic counter measures), and the ability to carry smart bombs. However, the A-10 could stay in service indefinitely due to both its low cost and its unique capabilities which the F-35 simply cannot incorporate such as its cannon, ruggedness, and slow flying capabilities.

Turbofans made inroads into civilian aircraft but had not been much use in military circles. These engines held several advantages which made them an excellent choice for the A-10. They offered high fuel efficiency, were quieter than the turbojet & had a lower heat signature.

Once the designers chose the type of engine (twin General Electric TF34-GE-100 turbofans later upgraded to the TF34-400A) another issue arose- where to put them. The area under the wing was reserved for the heavy ordnance load. The area near the rear of the fuselage was the best location & placing the engines there also offered several advantages. It negated a potential yaw problem, decreased the possibility of foreign objects being sucked into the engines & removed the engines from the main flow of the exhaust from the gun. The forward fuselage & wings also shield the engines from ground fire in the frontal section & the vertical fins & rudder guard the engines heat signature from the side alleviating some of the aircraft's vulnerability to heat seeking missiles.

The TF34, a 9,065 - 9,275 lbs (4082.3 - 4207.1 kg) thrust range class turbofan engine, delivers the highest thrust to weight ratio and the lowest specific fuel consumption in the class.

The TF34 is the father of the CF34, a commercial version that powers business jets and regional jet airliners.

The first TF34 was shipped in February 1971 and was first delivered on the S3 in January 1974.

The flat-rated TF34-GE-101 doubles the hot day thrust output over current engines, eliminating take-off gross weight limitations that preclude today's A-10 from delivering its most powerful mission punch.

The TF34 engine enables the the A-10 aircraft to operate from short, remote airfields, withstand frequent exposure to ground fire and provide effective close-air support for ground forces.

Today, more than 460 engines are in service with the U.S. Navy and more than 1,050 are in service with the U.S. Air Force. With more than 11 million fleet hours, the TF34 is projected to remain in service beyond 2028.

Lockheed Martin Systems Integration-Owego is prime contractor for the programme. First flight of the upgraded A-10C was in January 2005. A contract for Low-Rate Initial Production (LRIP) of 72 units was awarded in March 2005. The first was delivered to the Baltimore Air National Guard in August 2006.

A contract for full-rate production of 107 units was placed in August 2006 with first operational deployment in May 2007. Kit installation is scheduled to conclude in 2009.

A parallel programme will give the A-10 new engine pylons. It is possible that the A-10 engine will also be upgraded if funding is made available.

In February 2004, Lockheed Martin was awarded a contract for the integration of the Sniper XR targeting pod on the A-10 as part of the PE programme. Sniper XR includes mid-wave FLIR (Forward-Looking Infrared), dual mode laser, CCD-TV, laser spot tracker and IR marker.

Fairchild A-10 Thunderbolt II

1975
General Electric
TF34-400A

The A-10's powerplant
Click image for an enlargement

History

Technical Details

The General Elecrtic GE TF34-400A now used for nearly all subsonic transport aircraft is a small version of the classic high bypass turbofan. The TF34 programme was launched in 1967 to power the US Navy's Lockheed S-3A Viking anti-sub aeroplane, and was later used on the Air Force's A-10 close air support aircraft & on Canadair's Challenger business jet & RJ series of regional jet transports.The first prototype ran in 1969, & production deliveries began in 1974. By 1984, over 2100 of these engines had been produced for military aircraft & many more have been produced since 1979 for Canadair's civil aircraft.

The TF34's high bypass ratio & moderately high overall pressure ratio enable it to have low fuel consumption, and its low fan pressure ratio gives it a low noise signature, important attributes for transport aircraft. Military TF34's ranged in takeoff thrust from 9,065 pounds (4,112 kg) for the A-10 to 9,275 pounds (4207.1 kg) for the S3A, while commercial CF34's ranged from 7,990 pounds (3624.2) for the early Challengers to 9,220 pounds (4182.1 kg) for the RJ100. The upgrade CF34-3B of the 1990's had an improved compressor that gave 3 % lower fuel consumption with lower turbine temperatures.

The 9000 pound (4082.3 kg) thrust class TF34 was derived from GE's T64 turboprop by scaling it up 20% & adding a fan to the front of the engine in place of a propeller. The low pressure spool consists of a single stage titanium fan, driven by a 4-stage uncooled axial-flow turbine at the rear via a shaft passing through the hollow centre of the high pressure spool. The HP spool has a 14-stage axial-flow compressor, having a rather high pressure ratio & using variable-angle starter vanes to improve low-speed operation.The single annular combustor has 12 fuel injectors.

The TF34's high bypass ratio & moderately high overall pressure ratio enable it to have low fuel consumption, and its low fan pressure ratio gives it a low noise signature, important attributes for transport aircraft. Military TF34's ranged in takeoff thrust from 9,065 pounds (4,112 kg) for the A-10 to 9,275 pounds (4207.1 kg) for the S3A, while commercial CF34's ranged from 7,990 pounds (3624.2 kg) for the early Challengers to 9,220 pounds (4182.1 kg) for the RJ100. The upgrade CF34-3B of the 1990's had an improved compressor that gave 3 % lower fuel consumption with lower turbine temperatures.

Type:2-spool, axial flow, high bypass ratio turbofan.

Pressure Ratio:21.0; bypass ratio 6.2.

Fan: Single stage; 338 pound/sec airflow, 14.0 pressure ratio; 7365 rpm.

Compressor: 14-stage axial; 47.0 pounds (21.32kg)/sec airflow, 14.0 pressure ratio; 17,900 rpm.

HP Turbine: 2-stage axial; hollow colled airfoils; 1,495 degree Fahrenheit (813 Celsius) exit temperature.

LP Turbine: 4-stage axial; solid uncooled airfoils.

Exhaust System: Two concentric fixed area converging nozzles; outer nozzle for fan bypass flow & inner nozzle for LP turbine exhaust.

Diameter/length: 52.2 inches (1,326 mm)/100.0
inches (2,540 mm)

Weight 1,458 pounds (661.3 kg)
Thrust 9,275 pounds (4207.14 kg) at sea level

Fuel Consumption: 0:363 pounds (0.165 kg) per pound (per kilo) of thrust.
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