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OV-10 Bronco
	A USAF OV-10A firing a white phosphorus smoke rocket to mark a ground target
Role	Light attack and observation aircraft
Manufacturer	North American Rockwell
First flight	16 July 1965
Introduced	October 1969
Primary users	United States Marine Corps; United States Air Force; United States Navy; Philippine Air Force

The North American Rockwell OV-10 Bronco is a turboprop-driven 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 three tons of external munitions, and loiter for three or more hours.

[edit] Development

[edit] Background

The original vision was developed by an informal collaboration of W.H. Beckett and Colonel K.P. Rice, USMC, who met at Naval Air Weapons Station China Lake, California in the 1960s. The concept was one of 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 uninterested 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 aircraft. Weapons were to be mounted on the centerline to get efficient unranged aiming like the P-38 Lightning and F-86 Sabre aircraft. The inventors' favored strafing weapons were 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 would thereby avoid the back blast.

They developed a basic platform meeting the 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 to sell the aircraft.

Rice states:

"The military definition of STOL (500 ft to a 50 ft obstacle) allows takeoff and landing in most of the areas in which limited war might be fought. In addition, the airplane was designed to use roads so that operation would even be possible in jungle areas where clearings are few and far between. As a result the wingspan was to be limited to twenty feet and a heavy trailing arm type landing gear with a tread of 6.5 ft was provided for operation from roads. Float operation was to be feasible... "^[1]
"...it is quite feasible to design the various components so that it can be disassembled easily and stored in a box that would fit in a 6x6 truck bed together with the equipment needed for re-assembly in the field. It could thus be transported by amphibious shipping and either heli-lifted or driven ashore by a 6x6 truck."^[2]

[edit] 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. Retired Marine Corps aviators K.P. Rice and William H. Beckett originated the LARA concept as an aircraft with very small wingspans of around 20 feet that could land in nearly any small clearing and use the same ammunition and fuel as ground troops used. Rice's and Beckett's "L2 VMA" concept also would have the aircraft ground-mobile so it could be co-located with ground units and not require hard-surface runways and air bases.

LARA 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 O-1 Bird Dog and 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-engined, two-man aircraft that could carry at least 2,400 pounds (1,100 kg) of cargo, six paratroops or stretchers, and be stressed for +8 and -3 gs (basic aerobatic ability). It also had to be launchable from an aircraft carrier, fly at least 350 miles per hour (560 km/h), take off in 800 feet (240 m) and convert to an amphibian. Various armament had to be carried, including four 7.62 mm (0.300 in) machine guns with 2,000 rounds, and external weapons including a 20 mm (0.79 in) gun pod and Sidewinder missiles.

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

In August 1964, the NA-300 was selected. A contract for seven prototype aircraft was issued in October 1964. General Dynamics/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 Bronco. 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 premiere COIN (COunter Insurgency) aircraft of the next 30 years. It failed to live up to Rice's L2 VMA concept because DoD insisted on 40-foot (12 m) long wings which made it depend on airbases. Rice concludes:

"The original concept of a small, simple aircraft that could operate close to the supported troops had been almost completely eviscerated by the 'system.' The ability to operate from roads (20 ft span and 6.5 tread) had been ignored, and performance compromised by the short 30 ft span, the extra 1,000 lb for the rough field landing gear and another 1000 lb of electronics. The "light, simple" airplane also had a full complement of instruments, ejection seats and seven external store stations. The concept of using ground ordnance and a bomb bay had been ignored, although it did have provisions for four M60 [medium] machine guns. In spite of this growth (almost double the size and weight of our home built), the YOV-10 still had great potential. It would not achieve the advantages of integration with the ground scheme of maneuver, but it did have capabilities at the low end of the performance envelope that were still valuable and unique."^[3]

The Bronco performed observation, forward air control, helicopter escort, armed reconnaissance, gunfire spotting, utility light air transport and limited ground attack. The Bronco has also performed aerial radiological reconnaissance, tactical air observation, artillery and naval gunfire spotting and 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.

[edit] Design

Visually, the OV-10 has a central nacelle containing pilots and cargo, and twin booms containing twin turboprop engines. The visually-distinctive item of the aircraft is the combination of the twin booms, with the horizontal stabilizer that connects them. The North Vietnamese nickname for an OV-10 was chuong lon ("pigpen"), perhaps because its tail empennage resembled a traditional Vietnamese pig enclosure.^{[citation needed]}

The OV-10 can perform short takeoffs and landings on aircraft carriers and large deck amphibious assault ships^[4] without using catapults or arresting wires, although for safety and clearance reasons the latter is most often not permitted. Further, the OV-10 was designed to takeoff and land on unimproved sites. Film footage of an OV-10 taking off of an artificially degraded runway which was shown at the North American Columbus Plant open houses during the 1970s. The cockpit has extremely good visibility for a tandem pilot and co-pilot provided by a wrap-around "greenhouse". With the second seat removed, it can carry 3,200 pounds (1,500 kg) of cargo, five paratroopers or two litter patients and an attendant. Empty weight was 3,161 kilograms (6,970 lb). Normal operating fueled weight, with two crew was 4,494 kilograms (9,910 lb). Maximum takeoff weight was 14,446 pounds (6,553 kg).

The bottom of the fuselage contains sponsons or "stub wings" that improves 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 assured that stores carried on the sponsons jettisoned cleanly. Normally four .30 in (7.62 mm) 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. The sponsons are easy to remove, and most unarmed Broncos have now had their sponsons removed.^{[citation needed]}

Racked armament in the Vietnam War was usually seven-shot 2.75 in (70 mm) rocket pods with marker or high-explosive rockets, or 5 in (127 mm) four-shot Zuni rocket pods. Bombs, ADSIDS air-delivered seismic sensors, Mk-6 battlefield illumination flares, and other stores were carried as well.^{[citation needed]}

[edit] 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 during the course of the Vietnam War, to all causes: USAF - 64, USN - 7, and the USMC - 10.^[5]

[edit] USMC

An OV-10A of VMO-1 operating from USS Nassau in 1983.

The OV-10 was first acquired by the U.S. Marine Corps. Each of the Marine Corps' 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 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.

The U.S. Marine Corps OV-10 Night Observation Gunship (NOGS) program modified four OV-10As to include a turreted forward-looking infrared (FLIR) sensor and turreted 20 mm (.79 in) M197 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. The U.S. Marine Corps lost 10 OV-10s during the Vietnam War to all causes.^[5]

Operation as forward air controllers in the U.S. Marines continued in both Active and Marine Air Reserve VMO squadrons through July 1994 and the Broncos were finally decommissioned in 1995. The decision to decommission the aircraft was in large part due to two USMC Broncos being shot down during Operation Desert Storm due to a lack of effective infrared countermeasures equipment. 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 U.S. Broncos were reassigned to civil government agencies in the U.S., while some were sold to other countries.

[edit] US Air Force

The USAF acquired the Bronco primarily as a FAC aircraft. The first USAF OV-10As for combat arrived in Vietnam on 31 July 1968 as part of Operation Combat Bronco, an operation test 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.^[6] 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 [OV-10A] [was] detected."^[7] 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), and for out-of-country missions to the 23d TASS (Nakhom Phanom in Thailand). The 23d TASS conducted missions in support of Operation Igloo White, Operation Prairie Fire/Daniel Boone, and other special operations.^[8]

An OV-10A at Patrick AFB, FL in 1980.

In April 1969 the USAF conducted an operational exercise, called Misty Bronco, 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 .30 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.^[9]

In 1971, the 23d TASS's OV-10A Broncos at 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 callsign Nail was the radio handle of this squadron. After 1974, these aircraft were converted back to an unmodified OV-10A standard.^[10]

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.^[5] At the beginning of the 1990s the USAF had replaced their OV-10A fleet with OA-37B and OA-10A aircraft.

An OV-10A of VAL-4 attacking a target in Vietnam

[edit] US 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 through 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 river boats.^[11] It succeeded in this role, although the US Navy did lose seven OV-10s during the Vietnam War to various causes.^[5] Other than OV-10 Fleet replacement training done in cooperation with Air Antisubmarine Squadon FOUR 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 OV-10s were subsequently transferred to the Marine Corps.^{[citation needed]}

[edit] International use

[edit] Colombia

In 1991, the USAF provided the Colombian Air Force with 12 OV-10A aircraft. 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.^[12] The remaining OV-10As were upgraded to OV-10D standard.

[edit] Indonesia

Indonesia purchased 12 OV-10F aircraft and operates them in COIN operations similar to the US Navy's Vietnam missions with their Broncos, but have retrofitted .50 in (12.7 mm) Browning heavy machine guns in place of the light .30 in (7.62 mm) machine guns.^[13] These aircraft were vital in the invasion of East Timor and ensuing COIN operations.

[edit] Philippines

The Philippine Air Force (PAF) received a total of 24 OV-10A from US stocks in 1991, later followed by a further nine from the United States,^[14] and 8 ex-Thai Air Force OV-10C models in 2003–2004.^[14]^[15] The aircraft is operated by the 16th Attack Squadron and 25th Composite Attack Squadron of the 15th Strike Wing, based in Sangley Point, Cavite.^[16] The PAF flies Broncos on search-and-rescue and COIN operations in various parts of the Philippines. The first two women combat pilots in the PAF flew OV-10s with the 16th. This squadron flew anti-terrorist operations in the Jolo Islands.^[17]

A crashed Philippine OV-10A at Clark Air Base in 2006.

Recent modifications by the PAF included upgrades in the engine and propeller (now sporting a four-bladed propeller), and flight controls and sensors.^{[citation needed]} A Service Life Extension Program has been started with all remaining serviceable OV-10s slated to go through the program. With the assistance of Marsh Aviation the PAF is currently overhauling and modernizing the airframe and its systems as well as replacing the increasingly difficult to maintain and service three bladed propeller with brand new units from Marsh Aviation and Hartzell. The program includes the replacement of the difficult to maintain three-bladed propeller, fitting of new gearboxes to improve maintainability, zero timing the airframes and overhauling of the aircraft's subsystems to extend the service life of the airframe, improve serviceability and make the fleet easier to maintain. In place of the old three bladed propeller, a new 100 in (254 cm) diameter propeller designed and manufactured by Hartzell has been fitted. In addition, the fleet is due to receive enough locally-built 20 mm (.79 in) gun pods to equip all aircraft.^{[citation needed]}

[edit] Thailand

A RTAF OV-10C at Korat in 1987.

The Royal Thai Air Force purchased 32 new OV-10C aircraft in the early 1970s for COIN usage.^[15] Reportedly Broncos won most Thai bombing competitions until F-5Es became operational. At one time Thailand even flew OV-10s as air-defense aircraft.^[15] In 2004, RTAF donated most of the OV-10s to the Philippines.^[15] Two OV-10 survivors are displayed in the Tango Squadron Wing 41 Museum in Chiang Mai and the RTAF Museum in Bangkok.

[edit] Venezuela

The Venezuelan Air Force has operated a number of new build OV-10Es and ex-USAF OV-10As over the years. On 27 November 1992, the aircraft were widely used by mutinied officers led by Hugo Chavez who staged an attempted coup d'état against former President Carlos Andrés Pérez. The rebels dropped bombs and launched rockets against Police and government buildings in Caracas. Four Broncos were lost during the uprising, including two shot down by a loyalist F-16 Falcon.^[18]

Venezuela's OV-10s are to be retired in the coming years. Originally Venezuela attempted to procure Embraer Super Tucano aircraft to replace the OV-10, but no deal was achieved which President Chavez claimed a result of pressure from the US government^[19]. Uniquely, the Venezuelan government has decided not to replace them with new fixed wing aircraft. Rather, the Venezuelan Air Force is replacing them with the Russian made Mil Mi-28 attack helicopter.^[20]

[edit] Lebanon

In 2009, the United States offered ten disarmed OV-10s for use as reconnaissance aircraft.^[14]^[21]

[edit] Civilian use

[edit] US Department of State Air Wing

The Department of State (DoS) aircraft are former USAF OV-10A and USMC OV-10D aircraft operated under contract by DynCorp International in support of U.S. drug interdiction and eradication efforts in South America. The aircraft carry civilian U.S. aircraft registration numbers and, when not forward deployed, are home based at a DoS/DynCorp facility at Patrick Air Force Base, Florida.^[22]

[edit] BLM

The Bureau of Land Management (BLM) acquired seven OV-10As for use as fire fighting aircraft, including the YOV-10A prototype. In this role, they would lead firefighting air tankers through their intended flight path over their target area. The aircraft were operated in their basic military configurations, but with their ejection seats disabled. The aircraft's existing smoke system was used to mark the path for the following air tankers. With the age of the aircraft, spare parts were difficult to obtain, and the BLM retired their fleet in 1999.^[23]

[edit] CALFIRE

Air Attack 460 at Fox Field during the October 2007 California wildfires

The California Department of Forestry and Fire Protection (CDF or CALFIRE) has acquired a number of OV-10As, including the six surviving aircraft from the BLM^[23] and 13 former U.S. Marine Corps aircraft in 1993 to replace their existing Cessna O-2 Skymasters as air attack aircraft.^[24] The CAL FIRE Broncos fly with a crew of two, a contract pilot and the CAL FIRE ATGS or Air Tactical Group Supervisor, whose job it is to coordinate all aerial assets on a fire with the Incident Commander on the ground. Thus, besides serving as a tanker lead-in aircraft, the OV-10A is also the aerial platform from which the entire air operation is coordinated.^[25]

[edit] Variants

YOV-10A - The original prototype.
OV-10A - Original production version.
OV-10B - Produced for Germany to use as target tugs, with a target towing pod was mounted underneath the fuselage. A clear dome replaced the rear cargo door. The rear seat was moved to the cargo bay to look backwards out the dome.
- OV-10B(Z) - A variation of the German target tug, with one J85-GE-4 turbojet mounted in a nacelle above the fuselage. A total of 18 aircraft were supplied to the Germans.^[26]
OV-10C- Export version for Thailand; based on the OV-10A.
OV-10E - Export version for Venezuela; based on the OV-10A.
OV-10F - Export version for Indonesia; based on the OV-10A.
YOV-10D - The prototype used to developed OV-10D Bronco.

An OV-10D during trials aboard USS Saratoga in 1985.

OV-10D - The second generation Bronco developed by the U.S. Marine Corps. It was an extensively modified A-model airframe. The D-model added a powerful Forward-Looking Infrared night-vision system with a camera mounted in a turret under an extended nose. It is easy to differentiate a D-model from an A. The D has a long nose with a ball turret underneath, while the A has a short rounded nose. The D also has bigger engines, so it has larger fiberglass props that can be distinguished by their rounded tips. The A has squared-off aluminum props. Other noticeable external differences are the square chaff dispensers midway down the booms on the D-model (often covered with a plate when not in use) and infrared-suppressive exhaust stacks (they take air in the front and mix it with the exhaust before it exits, to reduce the heat given off and thus the ability of a heat-seeking missile to track the aircraft). The D-model began life as the NOGS program.
- OV-10D+ - The next USMC upgrade, consisting of A and D aircraft being extensively reworked at MCAS Cherry Point Naval Air Rework Facility with new wiring and strengthened wings. Engine instrumentation was changed from round dials to tape readouts.
OV-10M (modified) - A modified, four-bladed version of OV-10A by Marsh Aviation for the Philippine Air Force.^[27]

[edit] Possible modernized variant

Boeing has recently put together plans internally to build a modernized, improved version of the OV-10 Bronco, called the OV-10X^[28], to satisfy a possible Air Force requirement for a light attack plane.^[29] According to Pentagon and industry officials, while the plane would maintain much of its 1960s-vintage rugged external design, the 21st century modernizations would include a computerized glass cockpit, intelligence sensors and smart-bomb-dropping capabilities. Boeing indicates that international interest in restarting production is growing, to compete with other light attack aircraft such as the T-6B Texan II, A-67 Dragon and EMB-314 Super Tucano.

[edit] Operators

Colombia: 7 in active service^[30]
Germany: all retired in 1990
Indonesia: Indonesian Air Force all grounded and to be replaced soon^[31]
Lebanon: 1 in active service, 9 to be delivered.^{[citation needed]}
Morocco: all retired
Philippines: Philippine Air Force 14 in active service^[32]
Thailand: Royal Thai Air Force all retired in 2003
United States

Venezuela: 7 in active service. All to be replaced by Mil Mi-28 attack helicopters.^[20]

[edit] Civil Operators

Department of State (Operated by DynCorp), primarily in Colombia
California Department of Forestry and Fire Protection.

[edit] Survivors

An OV-10 on static display at Hurlburt Field Air Park.

The original prototype YOV-10A was on display at the Yankee Air Museum at Willow Run Airport near Ypsilanti, Michigan. It had been fully restored by a former OV-10 crew chief. Sadly, this aircraft was totally destroyed in the fire that burned the museum to the ground in October 2004.
Another YOV-10A was one of the aircraft transferred to the BLM and subsequently to CAL FIRE, where it serves as a parts source.^[23]
There is currently an OV-10 at the Imperial War Museum Duxford in England, while not on obvious display, is clearly visible passing along the M11.
Many OV-10s are currently on static display throughout the United States. The National Museum of the United States Air Force near Dayton, Ohio has had one on display in Air Force markings for many years and has loaned two additional aircraft for display at the Hurlburt Field Air Park at Hurlburt Field, Florida. and the Museum of Aviation at Robins AFB, Georgia. Another aircraft in Marine Corps markings, on loan from the National Museum of Naval Aviation, is on display at the Flying Leathernecks Museum at MCAS Miramar, California.
The European Museum of Fighter Aircraft in Montelimar, France, has two Luftwaffe OV-10B, one on static display and another one still flying. This last one may be seen during air shows (registration F-AZKM). First can be used to provide parts to the second one.
An OV-10D, with Marine Observation Squardon (VMO-1) markings is on display at the Pima Air Museum in Tucson, Arizona. It is on loan from the National Museum of the Marine Corps.

[edit] Specifications

[edit] OV-10A

Data from Mesko^[33]

General characteristics

Crew: 2
Length: 41 ft 7 in (12.67 m)
Wingspan: 40 ft 0 in (12.19 m)
Height: 15 ft 2 in (4.62 m)
Wing area: 290.95 ft² (27.03 m²)
Empty weight: 6,893 lb (3,127 kg)
Max takeoff weight: 14,444 lb (6,552 kg)
Powerplant: 2× Garrett T76-G-410/412 turboprop, 715 hp (533 kW) each

Performance

Maximum speed: 281 mph (452 km/h)
Range: 576 mi (927 km)
Service ceiling: 24,000 ft (7,315 m)

Armament

Guns: 4 × 7.62x51mm M60C machine guns
Total stores stations: 5 fuselage and 2 underwing
Bombs: Bombs up to 500 lb
Rockets: 7- or 19-tube launchers for 2.75" FFARs or 2- or 4-tube launchers for 5" FFARs
Missiles: AIM-9 Sidewinder (Wing pylons only)
Other: SUU-11/A or Mk 4 Mod 0 gun pods

[edit] OV-10D

Data from Mesko^[34]