North American Rockwell OV-10A Bronco

The North American Rockwell OV-10 Bronco is an American twin-turboprop light attack and observation aircraft. It was developed in the 1960s as a special aircraft for counter-insurgency (COIN) combat, and one of its primary missions was as a forward air control (FAC) aircraft. It can carry up to 3,200 lb (1,450 kg) of external munitions and internal loads such as paratroopers or stretchers, and can loiter for three or more hours.

Development

Background

The aircraft was initially conceived in the early 1960s through an informal collaboration between W.H. Beckett and Colonel K.P. Rice, U.S. Marine Corps, who met at Naval Air Weapons Station China Lake, California, and who also happened to live near each other. The original concept was for a rugged, simple, close air support aircraft integrated with forward ground operations. At the time, the U.S. Army was still experimenting with armed helicopters, and the U.S. Air Force was not interested in close air support.

The concept aircraft was to operate from expedient forward air bases using roads as runways. Speed was to be from very slow to medium subsonic, with much longer loiter times than a pure jet. Efficient turboprop engines would give better performance than piston engines. Weapons were to be mounted on the centerline to get efficient unranged aiming. The inventors favored strafing weapons such as self-loading recoilless rifles, which could deliver aimed explosive shells with less recoil than cannons, and a lower per-round weight than rockets. The airframe was to be designed to avoid the back blast.

Beckett and Rice developed a basic platform meeting these requirements, then attempted to build a fiberglass prototype in a garage. The effort produced enthusiastic supporters and an informal pamphlet describing the concept. W.H. Beckett, who had retired from the Marine Corps, went to work at North American Aviation to sell the aircraft.

Rice states:

Light Armed Reconnaissance Aircraft

A "tri-service" specification for the Light Armed Reconnaissance Aircraft (LARA) was approved by the U.S. Navy, Air Force, and Army and was issued in late 1963. The LARA requirement was based on a perceived need for a new type of "jungle fighting" versatile light attack and observation aircraft. Existing military aircraft in the observation role, such as the Cessna O-1 Bird Dog and Cessna O-2 Skymaster, were perceived as obsolescent, with too slow a speed and too small a load capacity for this flexible role.

The specification called for a twin-engine, two-man aircraft that could carry at least of cargo, six paratroopers or stretchers, and be stressed for +8 and −3 ''g'' (basic aerobatic ability). It also had to be able to operate from an aircraft carrier, fly at least , take off in and convert to an amphibian. Various armaments had to be carried, including four machine guns with 2,000 rounds, and external weapons including a gun pod with M197 electric cannon, and AIM-9 Sidewinder air-to-air missiles.

Eleven proposals were submitted, including: the Grumman Model 134R tandem-seat version of the already-fielded U.S. Army's OV-1 Mohawk (the U.S. Marine Corps dropped out of the Mohawk program in 1958), Goodyear GA 39, Beechcraft PD-183, Douglas D-855, Convair Model 48 Charger, Helio 1320, Lockheed CL-760, a Martin design, and the North American Aviation/ Rockwell NA-300.

In August 1964, the NA-300 was selected. A contract for seven prototype aircraft was issued in October 1964. Convair protested the decision and built a small-wing prototype of the Model 48 Charger anyway, which first flew on 29 November 1964. This was also a twin-boom aircraft that had a broadly similar layout to the OV-10. The Charger, while capable of outperforming the OV-10 in some respects, crashed on 19 October 1965 after 196 test flights. Convair subsequently dropped out of contention.

The Bronco started flying midway through the Charger's test program on 16 July 1965, and became one of the premier counter-insurgency (COIN) aircraft of the next 30 years. It did not achieve Rice's L2 VMA concept, because the DoD insisted on long wings, which made it depend on airbases. Rice concludes:

The Bronco performed observation, forward air control, helicopter escort, armed reconnaissance, utility light air transport and limited ground attack. The Bronco has also performed aerial radiological reconnaissance, tactical air observation, artillery and naval gunfire spotting, airborne control of tactical air support operations and front-line, low-level aerial photography. A prototype in Vietnam designed to lay smoke was extremely successful, kept in service by evaluators for several months, and only reluctantly released, was not purchased due to a perceived lack of mission.

Design

The OV-10 has a central nacelle containing pilots and cargo, and twin booms containing twin turboprop engines. The visually distinctive feature of the aircraft is the combination of the twin booms, with the horizontal stabilizer that connects them.

The aircraft's design supported effective operations from forward bases. The OV-10 can perform short takeoffs and landings, including on aircraft carriers and large-deck amphibious assault ships without using catapults or arresting wires. Further, the OV-10 was designed to take off and land on unimproved sites. Repairs could be made with ordinary tools. No ground equipment was required to start the engines. If necessary, the engines could operate on high-octane automobile fuel with only a slight loss of power.Burrows 2010, p. 66.

The aircraft had responsive handling and could fly for 5 1/2 hours with external fuel tanks.Burrows 2010, p. 65. The cockpit had extremely good visibility for a tandem pilot and co-pilot, provided by a wrap-around "greenhouse" that was wider than the fuselage. North American Rockwell custom ejection seats were standard, with many successful ejections during service. With the second seat removed, it can carry of cargo, five paratroopers, or two litter patients and an attendant. Empty weight was . Normal operating fueled weight with two crew was . Maximum takeoff weight was .

The bottom of the fuselage bore sponsons or "stub wings" that improved flight performance by decreasing aerodynamic drag underneath the fuselage. The sponsons were mounted horizontally on the prototype. Testing caused them to be redesigned for production aircraft; the downward angle of the sponsons on production models ensured that stores carried on the sponsons jettisoned cleanly. Normally, four 7.62 mm ( .308 in) M60C machine guns were carried on the sponsons with the M60Cs accessed through a large forward-opening hatch on the top of each sponson. The sponsons also had four racks to carry bombs, pods, or fuel. The wings outboard of the engines contain two additional racks, one per side.

Racked armament in the Vietnam War was usually seven-shot rocket pods with white phosphorus marker rounds or high-explosive rockets, or 5 in (127 mm) four-shot Zuni rocket pods. Bombs, ADSIDS air-delivered/para-dropped unattended seismic sensors, Mk-6 battlefield illumination flares, and other stores were also carried.

Operational experience showed some weaknesses in the OV-10's design. It was significantly underpowered, which contributed to crashes in Vietnam in sloping terrain because the pilots could not climb fast enough. While specifications state that the aircraft could reach , in Vietnam the aircraft could reach only . Also, no OV-10 pilot survived ditching the aircraft.

Operational history

The OV-10 served in the U.S. Air Force, U.S. Marine Corps, and U.S. Navy, as well as in the service of a number of other countries. A total of 81 OV-10 Broncos were ultimately lost to all causes during the course of the Vietnam War, with the Air Force losing 64, the Navy 7, and the Marines 10.Page numbers 269, 270: Hobson, Chris. ''Vietnam Air Losses, USAF, NAVY, and Marine Corps Fixed-Wing Aircraft Losses in Southeast Asia 1961–1973''. Hinkley UK: Midland Press, 2001. .

U.S. Marine Corps

The OV-10 was first acquired by the U.S. Marine Corps. Each of the Marine Corps's two observation squadrons (designated VMO) had 18 aircraft – nine OV-10As and nine OV-10Ds night observation aircraft. A Marine Air Reserve observation squadron was also established. The OV-10 operated as a forward air controller and was finally phased out of the Marine Corps in 1995 following its employment during Operation Desert Storm, which also saw the final combat losses of OV-10s by U.S. forces. Among these losses were two USMC OV-10s being shot down due to a lack of effective infrared countermeasures. It was also thought that the slow speed made it more vulnerable to anti-aircraft weapons. Forward air control passed mostly to ground units with laser designators and digital radios (GFACs) and the twin-seat F/A-18D Hornet (FAC(A)s). Most operational Broncos were reassigned to civil government agencies in the U.S., while some were sold to other countries.

The U.S. Marine Corps YOV-10D Night Observation Gunship System (NOGS) program modified two OV-10As (BuNo 155395 and BuNo 155396) to include a turreted forward looking infrared (FLIR) sensor, laser target designator and turreted 20 mm (.79 in) XM197 gun slaved to the FLIR aimpoint. NOGS succeeded in Vietnam, but funds to convert more aircraft were not approved. NOGS evolved into the NOS OV-10D, which included a laser designator, but no gun.

U.S. Air Force

The USAF acquired the Bronco primarily as an FAC aircraft. The first combat USAF OV-10As arrived in Vietnam on 31 July 1968 as part of "Operation Combat Bronco", an operational testing and evaluation of the aircraft. These test aircraft were attached to the 19th Tactical Air Support Squadron, 504th Tactical Air Support Group at Bien Hoa Air Base in South Vietnam. The test roles included the full range of missions then assigned to FAC aircraft, including day and night strike direction, gunship direction, bomb damage assessment, visual reconnaissance, aerial artillery direction, and as escorts for aircraft engaged in Operation Ranch Hand. The aircraft's ability to generate smoke internally was utilized for strike direction and "in four specific instances under conditions of reduced visibility, the smoke was seen by strike aircrews before the V-10A asdetected." Operation Combat Bronco ended on 30 October 1968.

After the end of Combat Bronco, the USAF began to deploy larger numbers to the 19th TASS (Bien Hoa), 20th TASS (Da Nang Air Base), and for out-of-country missions to the 23d TASS ( Nakhom Phanom in Thailand). The 23d TASS conducted Operation Igloo White, Operation Prairie Fire/Daniel Boone, and other special operations missions.

Between 1968 and 1971, 26 pilots from the Royal Australian Air Force (RAAF) and Royal New Zealand Air Force (RNZAF) flew the OV-10A on FAC sorties, while attached to USAF squadrons. The 19th TASS hosted 13 RAAF pilots and three from the RNZAF; another seven RAAF pilots and three from the RNZAF were assigned to the 20th TASS. (Consequently, the Australian War Memorial has acquired an OV-10A ''67-14639'', which was flown by some of these pilots.)

From April to June 1969 the USAF conducted an operational exercise called ''Misty Bronco'' in South Vietnam's III Corps Tactical Zone to evaluate the OV-10A's performance as a light strike aircraft. The results were positive and as of October 1969 all USAF OV-10As were to be armed with their internal .308 in (7.62 mm) M60C machine guns, which had generally been left out during the Combat Bronco evaluations and subsequent deployment. High explosive 2.75 in (70 mm) rockets were also authorized for use against ground targets.

In 1971, the 23d TASS's OV-10A Broncos received modifications under project ''Pave Nail''. Carried out by LTV Electrosystems during 1970, these modifications primarily included the addition of the ''Pave Spot'' target laser designator pod, as well as a specialized night periscope (replacing the initial starlight scopes that had been used for night time operations) and LORAN equipment. The call sign ''Nail'' was the radio handle of this squadron. These aircraft supported interdiction of troops and supplies on the Ho Chi Minh Trail by illuminating targets for laser-guided bombs dropped by McDonnell F-4 Phantom IIs. After 1974, these aircraft were converted back to an unmodified OV-10A standard.

At least 157 OV-10As were delivered to the USAF before production ended in April 1969. The USAF lost 64 OV-10 Broncos during the war, to all causes. In the late 1980s, the USAF started to replace their OV-10s with OA-37B and OA-10A aircraft. Unlike the Marine Corps, the USAF did not deploy the Bronco to the Middle East in response to the Iraqi invasion of Kuwait, as it believed that the OV-10 was too vulnerable. The final two USAF squadrons equipped with the Bronco, the 19th and 21st Tactical Air Support Squadron (TASS) retired the OV-10 on 1 September 1991.Willis 2010, pp. 68–69.Dorr and Mills 1992, p. 330.

In 2012, $20 million was allocated to activate an experimental unit of two OV-10s, acquired from NASA and the State Department. Starting in May 2015, these aircraft were deployed to support Operation Inherent Resolve flying combat missions over Iraq and Syria, flying more than 120 combat sorties over 82 days. It is speculated they provided close air support for Special Forces missions. The experiment ended satisfactorily, but an Air Force spokesman stated it remains unlikely they will invest in reactivating the OV-10 on a regular basis because of the overhead cost of operating an additional aircraft type.

U.S. Navy

The U.S. Navy formed Light Attack Squadron Four (VAL-4), the "Black Ponies", on 3 January 1969, and operated in Vietnam from April 1969 to April 1972. The Navy used the Bronco OV-10A as a light ground attack aircraft, for interdiction of enemy logistics, and fire-support of Marines, SEALs and naval riverine force vessels.Myrsky 1987, pp. 76–78. It succeeded in this role, although the U.S. Navy did lose seven OV-10s during the Vietnam War to various causes. Other than OV-10 Fleet replacement training done in cooperation with Air Antisubmarine Squadron Forty-One (VS-41) at NAS North Island, California, VAL-4 was the only squadron in the U.S. Navy to ever employ the OV-10 and it was decommissioned shortly following the end of the Vietnam War. VAL-4's surviving OV-10s were subsequently transferred to the Marine Corps.Dorr and Mills 1992, pp. 327–328.

At least two Broncos were used as test beds in the 1970s at the Naval Air Test Center (NATC) at NAS Patuxent River, Maryland.

Two OV-10s were evaluated for special operations, and the USMC lent 18 aircraft for operation by VAL-4 in Vietnam.

In 2015, two OV-10Gs were assigned for light attack operations in Iraq under the "Combat Dragon II" program and completed 120 missions.

In 2019, the first of two former VAL-4 aircraft returned to flight by the OV-10 Squadron, Chino, California. Bureau numbers 155493 "Holy Terror" and 155474 "White Lightning". Extensive restoration work of more than 18 months performed by California Aerofab went into 493's return to flight and 155474 expected to fly by 2020.

Colombia

In 1991, the USAF provided the Colombian Air Force with 12 OV-10As. Later, three ex-USMC A-models were also acquired to provide parts support. Colombia operates the aircraft in a COIN role against an active insurgency. At least one aircraft has been lost in combat."Colombian Broncos (Fuerza Aérea Colombiana)."
''OV-10Bronco.Net'', The OV-10 Bronco Association, 9 December 2000. Retrieved: 10 May 2009. The remaining OV-10As were upgraded to OV-10D standard. In November 2015, and after 24 years of service, the Colombian Air Force retired all of its remaining OV-10 aircraft. (Spanish)

Germany

The OV-10B variant was produced for Germany to use as target tug. Eighteen aircraft were delivered in the late 1960s and they were equipped with target towing equipment inside the fuselage. A transparent plastic dome replaced the rear cargo door and a rear seat was installed in the cargo bay to look backwards out of the dome. After a long career the Bronco was replaced by the Pilatus PC-9 in 1990 and all aircraft were retired and sent to various museums, technical schools and used as ABDR (Aircraft Battle Damage Repair).

Indonesia

The Indonesian Air Force purchased 12 OV-10F aircraft and operated them in COIN operations similar to the U.S. Navy's Vietnam missions with their Broncos, but retrofitted .50 in (12.7 mm) Browning heavy machine guns in place of the .308 in (7.62 mm) machine guns."Indonesian OV-10s."
'OV-10Bronco.Net'', The OV-10 Bronco Association, 9 December 2000. Retrieved: 10 May 2009. These aircraft were based in Lanud Abdulrachman Saleh Air Force Base in Malang, East Java and were vital in the invasion of East Timor and ensuing COIN operations. In 1977, they were also used during the aerial bombardments of Amungme villages near Freeport-McMoRan area of operations, West Papua, in response to OPM attacks on the mining company facilities, and of Dani villages in Baliem Valley, also in West Papua, in response to rebellion against enforced participation in the Indonesian general election. Due to the lack of U.S. bombs, the Indonesian Air Force modified the bomb racks to carry Russian bombs. The Indonesian Air Force plans to replace their OV-10Fs with EMBRAER Super Tucanos following a fatal accident on 23 July 2013. The Indonesian Air Force retired the OV-10F from service in 2007.

Morocco

The Royal Moroccan Air Force acquired six former-U.S. Marine Corps OV-10As in 1981. Based in Marrakesh Menara Airport

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