Staff Writer (Updated: 5/2/2015):
Externally, design of the Bronco was very unique in nature, sporting a high-mounted, straight monoplane wing assembly with cut-off wing tips. Each wing fitted underslung engine nacelles with powerplants mounting three-bladed propeller systems. The undercarriage was conventional with two main gears (fitted with single wheels) retracting into each engine nacelle underside and a nose gear (also fitting a single wheel)retracting forward. The Bronco maintained a twin boom layout extending aft to two vertical tail fins with the booms joined by a high-mounted horizontal tailplane. The fuselage was made up of a central nacelle fitted between the engines and positioned at the middle of the wing span. Side fuselage "sponsons", containing the 7.62mm M60 machine gun armament, protruded from the lower rear fuselage area. The sponsons also contained four weapon station hardpoints underneath.
The pilot and co-pilot sat in tandem in a full-windowed "greenhouse-style" cockpit with generally great visibility from any direction but to the rear. The cockpit was positioned as such that forward seat was held out well past the engines themselves. Both cockpit positions were afforded ejection seats for improved crew survivability ( helped along by the Broncos inherently rugged design and construction). The fuselage nacelle featured a cabin area at rear with space for could fit two medical litters and one medical attendant or five combat-ready infantrymen. Up to 3,200lbs of supplies could also be taken aboard if need be.
As a close-support, low-flying, light strike aircraft, armament of the Bronco naturally became the system's forte. Standard fittings included 4 x 7.62x51mm M60C machine guns in fuselage sponsons (the prototype YOV-10D trialed a 1 x 20mm M197 cannon in their place). Up to 3,600lbs of mixed ordnance could be carried externally on one under-fuselage, four under-sponson and two underwing weapons store stations. Armament included air-to-surface rockets in 7- or 19-tube launchers firing 2.75" rockets or 2- or 4-shot launchers firing 5" rockets in either their Folding-Fin Aerial Rocket (FFAR - otherwise known as "Zuni") or WAFARs (Wrap-Around Fin Aircraft Rockets). The Bronco was also given the capability to engage aerial inbound targets by its provision for 2 x wing-mounted AIM-9 Sidewinder short-ranged air-to-air missiles. Other munitions include the mounting of the SUU-11/A or Mk 4 Mod 0 series gun pods while use of conventional bombs rounded out armament capabilities. External fuel tanks could take the place of armament if needed.
The OV-10A fitted two Garret-brand T76-G-410/412 series turboprops delivering up to 715 horsepower each engine. Performance included a top speed of 281 miles-per-hour, a cruise speed of 223 miles-per-hour, an operational range of 576 miles and a service ceiling upwards of 26,000 feet. The OV-10A represented the initial Bronco production model. The OV-10B and OV-10B(Z) were both target tugs produced for Germany, the latter fitted with a J85-GE-4 turbojet engine. Designations for the C-, E- and F-models were all for export to Thailand, Venezuela and Indonesia respectively and all based on the OV-10A production model.
The OV-10M was a modified OV-10A model exclusively for the Philippines Air Force. These Broncos were fitted with a new four-blade propeller system. Work was handled by Marsh Aviation.
The YOV-10D appeared as two modified OV-10A prototype forms for the USMC Night Observation Gunship System (NOGS) program during the Vietnam War. They were used operationally in the war and proved successful, being outfitted with an experimental 20mm XM197 three-barreled Gatling cannon in a belly-mounted turret and a combination FLIR/laser target designator in a nose-mounted turret. Engines were the standard 715 horsepower installations used prior. Despite their positive performance in combat, the design did not enter serial production and, instead, led to the OV-10D production variant which lacked the 20mm XM197 turreted cannon (the M197 was later featured on the Bell AH-1J Cobra attack helicopter).