In 1939, after placing 2nd in Bendix trophy race, Art Bussy, flying the Bellanca 28-92 attempted a crossing of the mid-Atlantic, coming up short and landing in Farralon. Tha aircraft, having landed without permission, was impounded, and eventually purchased from the owner, Bellanca Aircraft. The Farralonians converted the aircraft for long-range reconnaissance as the Bellanca Binturong. Subsequently, Capstan purchased a license ot build further examples, and began a line of development.
The first development involved replacing the wing mounted Menasco engines with the same Rnager engine mounted inthe nose. This gave a significant power increase and allowed greater load-carrying, range, and speed. This became the Binturong II.
The Binturong III came when Capstan decided to replace the three engines with two, more-powerful Curtiss Conquerors. This freed up the nose for armament, leading to the long-range attack variant armed with two locally desinged and produced 32 mm cannon and two .50 calibre machine guns.
In the Mark IV, the two engines were replaced by a single, even more powerful Allison V-1710 engine. The former wing engine nacelles were retained to house the main landing gear and its retraction mechanism as well as additional fuel. The role for the Mk Iv reverted to the original long-range reconnaissance.