AVIATION FANS

A-10 Thunderbolt II is a single-seat, twin-engine jet aircraft designed to provide close air support (CAS) of ground forces by attacking tanks, armored vehicles, and other ground targets. As a secondary mission, it provides airborne forward air control, guiding other attack aircraft against ground targets. It is the first US Air Force aircraft designed exclusively for close air support (CAS) of ground forces. The official nickname comes from the P-47 Thunderbolt of World War II, a plane that was particularly effective at the CAS mission. However, the A-10 is more commonly known as Warthog or simply Hog. In the USAF inventory, the same airframe is also designated OA-10 when used primarily in a forward air control role.

Features

The A-10 has superior maneuverability at low speeds and altitude, thanks to straight, wide wings. These also allow short takeoffs and landings, permitting operations from rugged, forward airfields near front lines. The plane can loiter for extended periods of time and operate under 1,000 feet (300 m) ceilings with 1.5-mile (2.4 km) visibility. It typically flies at a relatively slow speed of 180 knots (200 mph or 320 km/h), which makes it much better candidate for the ground-attack role than fast fighter-bombers, which often have difficulty targeting small and slow-moving targets.

The 'Warthog' is exceptionally hardy, with a strong airframe that 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. The aircraft is designed to fly with one engine and half a wing torn off. Self-sealing fuel tanks are protected by fire-retardant foam. Additionally, the main landing gear is designed so that the wheels semi-protrude from their nacelles when the gear is retracted so as to make gear-up landings (belly landing) easier to control and less damaging to the aircraft's underside.

Cockpit

The cockpit and parts of the flight-control system are protected by 900 pounds (400 kg) of titanium armor, referred to as a "titanium bathtub." The tub has been tested to withstand multiple strikes from 20 mm cannon fire. The thickness of the titanium varies from ½ an inch to 1½ inches determined by study on likely trajectories and deflection angles. This protection comes at a cost, though; the armor plating itself weighs almost 6% of the entire 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 bath that is directly exposed to the pilot is covered by a multi-layer nylon spall shield. The protection for the pilot from above obviously comes second to the necessity for the pilot to have good all-round vision. The canopy cannot protect the pilot as well as the titanium, but the bullet-proof diffusion-bonded stretched-acrylic canopy can withstand small arms fire and is spall-resistant, although the canopy needs to be penetrable by the ejection seat.

The cockpit is equipped with a head-up display, which is used for targeting and weapon aiming, a Have-Quick secure radio communications system, inertial navigation and a Tactical Air Navigation (TACAN) system.
Lockheed Martin has begun delivery of 21 USAF A-10 aircraft with the embedded global positioning system/inertial navigation system (EGI), which pinpoints the exact location of the aircraft. The aircraft are also to be fitted with BAE Systems Terrain Profile Matching systems (TERPROM).

The pilot is equipped with night-vision goggles and also the infrared imaging display of the Maverick AGM-65.
 

Engines

One of the characteristic features of this aircraft is the placement of the General Electric TF34-GE-100 turbofan engines. There are many reasons for the location of the engines on the Warthog. First, as this aircraft was expected to be operated from forward air bases, often with semi-prepared substandard runways, there would be a high risk of FOD (Foreign Object Damage). The height of the engines significantly lowers the chance of sand or stones damaging the complex parts of the jet engines. This also means engines can remain running, allowing for shorter servicing and rearming turn-around times by ground crew. Servicing and rearming are further helped by wings closer to ground than for wing mounted engines. As mentioned above the position also reduces the IR signature which starts low anyway due to the high bypass ratio of the engines. The bypass ratio is 6:1 and so the engines are very quiet which aids against detection. Because of their high position, the engines are angled upward nine degrees to bring the combined thrust line closer to the aerodynamic center of the aircraft. This avoids trimming measures to counteract a nose down pitching moment if the engines were parallel to the fuselage. The engines, being particularly heavy components, require a high degree of strength in their support. Therefore forged engine-mounting nacelle frames are pin jointed to machined support beams.

 All four fuel tanks are near the center of the aircraft thus decreasing the likelihood of them being hit or being separated from the engines. There are several methods employed to protect the tanks themselves. The tanks are separate from the fuselage and so projectiles would need to penetrate the skin before reaching the tank. The refueling system is purged after use so that there is no fuel unprotected anywhere in the aircraft. All pipes self-seal if they are compromised. Most of the fuel system components are situated inside the tanks so that if a leak were to occur from the component the fuel would not be lost. If a tank does get damaged there are check valves that can ensure that fuel does not flow into the compromised tank. The most important fuel system protection aid is the reticulated polyurethane foam that is sprayed into the empty space in a tank holding 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.  

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 heatseeking missiles. The placement of the engines partially shields them from anti-aircraft fire behind the wings and tail. The A-10 can fly even after the loss of one side of the tail, â…” of a single wing, and one engine.

Precision Engagement Upgrade Program

The Precision Engagement upgrade program for the A-10 includes enhanced precision target engagement capabilities, which will allow the deployment of precision weapons such as JDAM (Joint Direct Attack Munitions) and Wind Corrected Munitions Dispenser (WCMD), as well as enabling an extension of the aircraft's service life to 2028.
Improvements include: hands-on throttle and stick control, two new Raytheon Technical Services 5in x 5in multifunction cockpit displays, situational awareness datalinks, digital stores management system, Integrated Flight and Fire Control Computer (IFFCC) from BAE Systems Platform Solutions for automated continuously computed weapons delivery, Sniper XR targeting pod for precision-guided weapons and helmet-mounted sighting system.

Weapons Systems

Although the A-10 can carry a considerable weight of disposable stores, its primary built-in weapon is the 30 mm GAU-8/A Avenger Gatling gun. One of the most powerful aircraft cannons ever flown, it fires large depleted uranium armor-piercing shells at a rate of about 3,900 rounds per minute (50 rounds per second during the first second followed by 70 rounds per second). The massive shells and high muzzle velocity allow the Avenger to destroy heavily armored main battle tanks in as few as 6 direct hits. The gun is accurate as well, capable of placing 80% of its shots within a 20-foot wide circle from a distance of 1 mile while the aircraft is in flight. The fuselage of the plane is actually built around the gun (for instance, the nosewheel is offset to starboard so that each barrel of the gun can be aligned on the centreline when it fires.) The A-10 carries 1,350 rounds of 30 mm ammunition and the damage caused by a proportion of those rounds prematurely firing due to impact of an explosive shell would be catastrophic. It is for this reason that a great deal of effort has been taken to protect the 5 ft (1.52 m) wide, 9 ft (2.74 m) long drum. There are many plates of differing thicknesses between the skin and the drum. These plates are called trigger plates because when an explosive shell hits a target it first penetrates its armor, then detonates. As the drum has many layers of thin armor the shell's detonation is triggered before reaching the drum. Then a final layer of armor around the drum itself protects it from fragmentation damage.

The aircraft has eleven stores pylons, providing an external load capacity of 7,260kg. There are three pylons under the fuselage and the loads can be configured to use either the centre-line pylon or the two flanking fuselage pylons.
For weapon guidance, the aircraft can be fitted with Pave Penny laser guidance / electronic support measures, pod installed on the starboard fuselage pylon. Each wing carries four stores pylons: three outboard and one inboard of the wheel fairing. The A-10 can carry up to ten Maverick air-to-surface missiles. The Raytheon Maverick AGM-65 missile uses a variety of guidance systems, including imaging infrared guidance and warheads, including a high-penetration, 57kg conical-shaped charge warhead. Range is more than 45km. The A-10 can also carry the Sidewinder air-to-air missile, which is an all-aspect short-range missile with maximum speed over Mach 2. The A10 is capable of deploying a wide range of ordnance: for example, the LDGP Mk 82 226kg, 500lb general-purpose bombs, BLU-1 and BLU-27/B Rockeye II cluster bombs and the cluster bomb unit CBU-52/71. The Northrop Grumman Litening ER (Extended Range) targeting pod has been successfully integrated on an A-10. Litening ER features a 640 x 512 pixel thermal imager, CCD TV, laser spot tracker / rangefinder, IR marker and laser designator.

General characteristics

• Crew: 1
• Length: 53 ft 4 in (16.26 m)
• Wingspan: 57 ft 6 in (17.53 m)
• Height: 14 ft 8 in (4.47 m)
• Wing area: 506 ft² (47.0 m²)
• Airfoil: NACA 6716 root, NACA 6713 tip
• Empty weight: 24,959 lb (11,321 kg)
• Loaded weight:
  • Standard: 30,384 lb (13,782 kg)
  • On CAS mission: 47,094 lb (21,361 kg)
  • On anti-armor mission: 42,071 lb (19,083 kg))
  • Max takeoff weight: 50,000 lb (23,000 kg)
  • Powerplant: 2× General Electric TF34-GE-100A turbofans, 9,065 lbf (40.32 kN) each
     

Performance

• Never exceed speed: 450 knots (520 mph, 830 km/h)
• Maximum speed: 380 knots (438 mph, 704 km/h) at 5,000 ft (1,500 m) with 6 Mk 82 bombs
• Cruise speed: 300 knots (340 mph, 560 km/h)
• Combat radius:
  • On CAS mission: 250 nm (290 mi, 460 km) at 1.88 hour single-engine loiter at 5,000 ft (1,500 m), 10 min combat
  • On anti-armor mission: 252 nm (166 mi, 267 km), 40 nm (45 mi, 75 km) sea-level penetration and exit, 30 min combat
  • Ferry range: 2,240 nm (2,580 mi, 4,150 km) with 50 knot (55 mph, 90 km/h) headwinds, 20 minutes reserve
  • Service ceiling: 45,000 ft (13,700 m)
  • Rate of climb: 6,000 ft/min (30 m/s)
  • Wing loading: 99 lb/ft² (482 kg/m²)
  • Thrust/weight: 0.36
     

Armament

• Guns: 1× 30 mm (1.18 in) GAU-8/A Avenger gatling gun with 1,350 rounds
• Hardpoints: 8× underwing and 3× under-fuselage pylon stations holding up to 16,000 lb (7,200 kg) and accommodating:
  •  Mark 82, Mark 83, and Mark 84 general-purpose bombs or
  • Mk 77 incendiary bombs or
  • BLU-1, BLU-27/B Rockeye II, BL755 and CBU-52/58/71/87/89/97 cluster bombs or
  • GBU-10 Paveway II, GBU-12 Paveway II, GBU-16 Paveway II and GBU-24 Paveway III laser-guided bombs or
  • AGM-65 Maverick air-to-surface missiles and AIM-9 Sidewinder air-to-air missiles or
  • LAU-68 Hydra 70 mm (2.76 in) and 127 mm (5.0 in) rocket pods or
  • Illumination flares, ECM and chaff pods or
  • ALQ-131 ECM pod