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New guilding for coin aircraft? Dominican Republic Super Tucano with 12.7-mm machine gun and armour protection.

When World War One ended, the only way for Britain's newly formed Royal Air Force (RAF) to justify its continued existence was to demonstrate that it could economically 'police' those territories in which dissidents periodically attempted to overthrow British rule.

World War Two sparked off the further dissolution of Europe's various empires. Early attempts to control insurgencies relied on standard fighters and bombers. For example, the French Air Force in Indo-China operated (inter alia) 80 Grumman F8F Bearcat naval fighters. Following the partition of Vietnam in 1954, the surviving 70 were handed over to the newly formed South Vietnam Air Force (VNAF).

In the early 1960s the Bearcat was replaced in VNAF service by the far more effective Douglas A-1 Skyraider, of which 308 were provided by the US Government. Aside from giving an increase in ordnance load, the larger size of the A-1 (which had twice the gross weight of the F8F) later allowed an observer to be accommodated in the belly of the aircraft, scanning the ground for targets of opportunity (Operation Blackeye).

The nature of ground attack in South Vietnam changed significantly in 1972 with the arrival of the shoulder-launched SA-7 missile (the KBM-designed 9M32). Despite the introduction of flare-dispensers, the only safe way to strike then was from above 10,000 ft, which meant the use of ground-based radar bombing systems. For example, the Cessna A-37 was equipped with the TPB-1 Bobs (Beacon-Only Bombing System), which allowed strikes through cloud, by day or night.

The Vietnam War illustrated the broad spectrum of aircraft required to fight a major Coin operation. The VNAF inventory peaked in 1974 at the remarkable total of 2075 aircraft, including 229 A-37s, 69 Douglas A-1E/Hs, 131 Northrop F-5A/B/E/RFs, 181 Cessna O-1s, 84 Cessna U-17A Skywagons, 66 Douglas C-47s, 54 DHC C-7A Caribous, 790 Bell UH-1s and 65 Boeing CH-47s. Other types included the AC-47 and Fairchild AC-119 gunships, the lesser-known EC-47 and RC-47 and the North American AT-28D and RT-28. The Cessna U-17A and DHC U-6A Beaver were used in both utility and psychological warfare duties. The principal transports were the C-47, Fairchild C-119G/K and C-123K and the Lockheed C-130A.

The US Air Force employed every element of its strike force, including the Boeing B-52D/G, which flew up to 1600 sorties per month against targets in South Vietnam. Where concentrations of insurgents were detected, a cell of three B-52s would take out a rectangle three kilometres long and one wide, bombing without warning from above 30,000 ft, with near precision provided by ground radar direction. Each aircraft could carry 84 bombs of 227 or 340 kg, giving a total warload of up to 28.6 tonnes. In the 1960s up to 138 B-52s were based at U-Tapao in Thailand and Andersen AFB on Guam.

On the use of heavy bombers in Coin operations, it may be added that Avro Lin-colns bad been used by the RAF in this context during the 1950s, both in the Malayan Emergency and in the Mau Mau uprising in Kenya. In the same decade, Lin-colns of the Argentine Air Force (FAA) were likewise employed against rebel forces during two attempted coups.

Special Needs

Coin operations in South Vietnam gave rise to a series of new aircraft developments, responding to the special needs of that conflict.

The large-scale use of helicopters to deploy ground forces created a need for attack helicopter escorts with tandem seats, a gun turret and later anti-tank missiles. The resulting Bell AH-1G Cobra led to today's AH-1Z Viper, the Boeing AH-64 Apache, the Eurocopter Tiger and the Mil-28.

To digress, in Afghanistan the Soviet Union followed a different approach with the Mil Mi-24 assault helicopter, which could also carry eight troops (firing through side windows). However, this line of development has since been abandoned. Likewise, the highly innovative single-seat Kamov Ka-50 has led only to the Ka-52 with side-by-side seating for forward air controller duties.

Vietnam also created a special need for villages to be given all-night protection, This led to a series of US Air Force transport aircraft being equipped with side-firing guns, but their usefulness declined when the SA-7 was introduced. Although the service intends to retain some Lockheed Martin AC-130s, and the US Marine Corps is to arm nine KC-130J tankers, the future of Hercules gunships is with lightweight standoff missiles. These can be delivered by much smaller platforms, such as single-engined turbo-props, although these naturally provide less endurance and warload.

The jungles of Vietnam contained targets that were not only time-sensitive but also difficult to see, especially from a high-speed jet. Quick reaction could often be achieved only by diverting part of a strike package that was already enroute from a distant major base to a preplanned target.

Ordnance would be delivered by reference to smoke provided by a forward air controller, who might be either on the ground or airborne in a Cessna O-1 or O-2, neither of which was designed for observation duties. The downside of this procedure was that the strike pilots were not familiar with the area, and they were not necessarily delivering ordnance best suited to the target.

Twin Turboprops

In order to achieve better and quicker strikes in Vietnam, a new forward air controller aircraft was specified with heavier armament. The result was the 6553-kg North American (later Boeing) OV-10 Bronco, a twin-turboprop stol aircraft with a maximum speed of 450 km/h. A tandem-seat 'glasshouse' was set just ahead of the propeller disks, giving an outstanding field of view and one of the world's noisiest cockpits. The OV-10 has four 7.62-mm machine guns in sponsons, and can carry up to 1630 kg of external ordnance.

In Vietnam the OV-10 was operated from 1969 by the US Air Force, Navy and Marine Corps. It was still in service in the forward air controller role at the time of the 1991 Gulf War, but in 1993-94 it was withdrawn due to its vulnerability to ground fire, the Air Force preferring the Fairchild-Republic A-10 and the Marine Corps the Boeing F/A-18D Hornet.

Boeing is considering a new-build OV-10(X) Super Bronco, an updated OV-10D with a modernised cockpit, day/night sensors, four 12.7-mm machine guns and a ventral three-barrel 30-mm turret. The cockpit noise problem would be addressed by using five-blade propellers of reduced diameter.

Like the OV-10, the A-10 had its origins in the Vietnam War. In 1967, responding to criticism of its performance in close support missions, the US Air Force issued a request for information (RFI) for a low-cost attack aircraft (A-X) to replace the A-l. At that stage, the A-X appeared likely to eventuate as a twin-turboprop that would combine stol performance with long loiter, low-speed manoeuvrability and enough weapons to suit any likely target of opportunity.

In essence, the A-X was expected to be similar to (but larger than) the twin-turboprop IA-58 Pucara, designed by Argentina's Fabrica Militar de Aviones (FMA). The Pucara has a gross weight of 6800 kg and a maximum speed of 500 km/h. It is armed with two 20-mm cannon and four 7.62-mm machine guns, and can carry 1500 kg of ordnance externally. It first flew in 1.969 and entered service in 1975. At least 108 were built.

The Pucara was used by the Argentine Air Force (FAA) in the Falk-lands/Malvinas conflict of 1982, this being the only FAA combat aircraft that could operate from the 1300-metre runway at Port Stanley airport. It was later employed in the Coin role by the Sri Lankan Air Force throughout the period 1993-96. Pucaras were also flown by the air forces of Colombia and Uruguay.

Its closest American equivalent was the US Army's 8215-kg Grumman OV-1 Mohawk, which had side-by-side seating. The Mohawk first flew in 1959 and some 380 were built. It was used only as a day/night sensor platform, and was retired in 1996.

Twin Jets

By the time that the A-X request for proposals was issued in 1970, the US Air Force was looking beyond Southeast Asia to the threat of a Warsaw Pact armoured drive through Western Europe. This very different scenario required higher speed, and hence the use of turbofans rather than turboprops. In addition, the A-X, now primarily intended to destroy multiple tanks on each sortie, was to be designed around the massive 30-mm General Electric Gau-8 cannon.

In 1973 the US Air Force selected as its A-X the Fairchild-Republic A-10A, which entered service in 1977. A total of 7 15 were delivered by 1984. The A-10 has a gross weight of 22,950 kg with 7200-kg of ordnance on eleven pylons. Maximum speed is 675 km/h.

Although the A-10 is undoubtedly effective in the Coin, close support and for ward air controller roles in a relatively benign environment, it failed to attract export orders. Most air forces prefer an aircraft with greater operational flexibility, since (unlike the US Air Force) they cannot rely on having airspace dominance.

The Sukhoi Su-25 differs from the A-10 in having two turbojets mounted close to the centreline, presumably to facilitate servicing at forward airstrips. In combination with a thinner wing, the flatter thrust-curve of the turbojets gave a higher maximum speed (950 km/h). The standard Su-25 has a maximum weight of 17,600 kg with 4400 kg of ordnance on eight pylons and a chin-mounted 30-mm GSh-2-30 cannon.

The Su-25 first flew in 1975. Two prototypes were tested in Afghanistan in 1980, and production aircraft were deployed there in 1981. However, the Mujahedin's acquisition of the (CIA-sup-plied) Redeye shoulder-launched missile in 1984 and Stinger in 1986 necessitated improved armour protection and the addition of up to 256 flares. Sukhoi claims that only 23 Su-25s were lost (none with the full modification standard) in around 64,000 sorties.

The Su-25 has also seen operational service over Chechnya (1994 to 95 and 1999 to 2003), in the later years (1986 to 1989) of the Iran-Iraq War, in the 1992 to 94 conflicts between Armenia and Azerbaijan and between Georgia and Abkhazia, and that between Ethiopia and Eritrea (1999 to 2000).

Over 1000 Su-25s were built, the single-seaters at Tbilisi in Georgia and the two-seaters at Ulan-Ude. Sukhoi states that around 500 are still in service with 16 air forces. Rosoboronexport no longer markets the Su-25, but the Ulan-Ude Aviation Plant still offers the Su-25UBM trainer upgrade and the radar-equipped single-seat Su-39, based on the two-seater airframe. The Su-39 has a design gross weight of 21,500 kg with 6000 kg of ordnance.

Beginning in 2006, the Russian Air Force began upgrading two wings of Su-25S aircraft to Su-25SM standard at a rate of at least six aircraft per year. The modifications include provisions for the R-73E air-to-air missile, the 122-mm S-13T rocket projectile and the TV-guided Kab-500Kr bomb.

The Su-25SM will eventually be replaced in Russian service by a derivative of the much smaller Yakovlev Yak-130 advanced trainer. This currently has a maximum design weight of 9000 kg with 3000 kg of ordnance on nine strongpoints. Maximum speed is 1050 km/h.

Deliveries of the Yak-130 'combatcapable trainer' are now taking place from Irkutsk, an initial twelve of 100 planned for domestic use being manufactured in parallel with 16 for Algeria. The close support derivative will presumably be a single-seater with armour protection based on that of the Su-25.

Single Turboprop

The twinjet Su-25 is possibly the best Coin aircraft to date, but where there is no threat from shoulder-launched missiles, a smaller single-engined turboprop may suffice. This suggests derivatives of basic trainers, or conversions of utility or agricultural aircraft.

In the basic trainer category, the Embraer Super Tucano was designed from the outset for Coin operations in addition to basic flying training. It first flew in 1999, and entered service in 2003. The Super Tucano has a gross weight of 5200 kg with 1550 kg of ordnance. Maximum speed is 593 km/h. In its class it is unusual in having armour protection, five pylons and two 12.7-mm machine guns mounted inside the wing.

Following an order for 99 Super Tucanos for the Brazilian Air Force (33 single-seat A-29As and 66 two-seat A-29Bs), of which 83 had been delivered bythe end of 2009, six export customers have purchased a total of 73. Colombian aircraft hit the headlines in 2008 with the bombing of a Fare (Revolutionary Armed Forces of Colombia) camp over the border in Ecuador.

One Super Tucano (believed to be owned by EP Aviation, a subsidiary of Xe Security, formerly Blackwater) has been equipped with a ventral sensor turret and is being evaluated by the US Navy for its potential in special operations under Phase One of (he Imminent Fury programme. A total of four are to be leased for Phase Two, a joint US Air Force/Navy effort to be funded in FY2010.

The much lighter (2950 kg) Beechcraft T-6 Texan II is unlikely to be rivalled numerically, with the US Air Force and Navy planning to acquire a total of 782 T-6A/Bs. At time of writing, 118T-6A/Cs had been ordered by five export customers, and top-up orders from Iraq, Israel and Morocco appear probable. The maximum speed of the T-6 is 585 km/h.

Hawker Beechcraft has teamed with Lockheed Martin to develop and promote the AT-6 derivative of the T-6 in response to the US Air Force's Light Attack Armed Reconnaissance (Laar) concept. The AT-6 is to have a strengthened airframe, an uprated engine and an integrated mission system, including a ventral sensor turret.

The Laar pre-solicitation document, issued by Air Combat Command in July 2009, describes as 'critical' the ability to fly a five-hour sortie, use semi-prepared surfaces and ferry over a distance of 1670 km. The aircraft may have one or more turbine engines. The ability to use 1830-metre fields, operate up to 30,000 ft and cruise continuously at 335 km/h are capabilities rated as 'desired'.

If the US Air Force Laar goes ahead, the contenders will be evaluated by the Air National Guard. A 100-aircraft order is envisaged, and the AT-6 is generally expected to win. Deliveries are reportedly to start in FY2012, with the first squadron operational by FY2013.

Although not a Laar contender, the Korea Aerospace Industries KT-1 is in broadly the same category as the T-6, with a maximum weight of 3311 kg in armed form. The South Korean Air Force has 85 KT-1 trainers and 20 KA-1 forward air controller aircraft. Indonesia has twelve KT-lBs, with an option on a further eight. The Turkish Air Force has ordered 40 KT-lTs (mostly to be built locally) and has 15 on option. KAI is currently developing the KT-IC with updated avionics and expanded armament capability.

At the 2009 Paris Air Show Air Tractor presented the AT-802U armed version of the AT-802A, an armoured crop-spraying aircraft that is used by the US State Department to destroy drug crops in some South American countries. A gross weight of 7260 kg allows for an external load of around 3460 kg on six hardpoints.

In the utility category, it may be noted that Alliant Techsystems has elivered to the Iraqi Air Force three AC-208B Combat Caravans. The AC-208B is a Cessna Grand Caravan with self-protection equipment, an air-to-air datalink, an EO-sensor turret with integral laser designator and provisions for Hellfire missiles. Firing trials were performed by a Combat Caravan of the IAF's No3 Sqn, based at Al Asad AB.
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Author:Braybrook, Roy
Publication:Armada International
Date:Apr 1, 2010
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