Boripatra • wp.archivoaereo.com

In the mid-1920s, Siam experienced the most favorable conditions for the development of its own air force. After World War I, NiD.29 fighters and Breguet XIVA2 bombers, considered among the most modern aircraft of their time, were purchased from France. Although their numbers were not large, Siam possessed one of the most powerful air fleets compared to other states.

Rightfully proud of their air force, Thai engineers, in cooperation with European colleagues, created the first aircraft of their own design intended for military purposes. This was a light bomber named Boripatra (sometimes also referred to as BT.2/TO.1) in honor of Defense Minister Prince Boripatra Sukumpant. Air Force Lieutenant Colonel Luang Vejayanrangsrit led the design team.

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Design and Development

During the design of the bomber, constructive solutions from French engineers were actively utilized. Overall, the first Thai bomber did not differ significantly from its European “counterparts.” Aircraft assembly began at the Aviation Factory.

In 1927, when the prototype aircraft, given the name Paribatra, was almost ready, the problem of equipping the machine with a modern engine became acute. Since the Renault company, whose engines held particular promise, quoted a rather high price for its products, the Thais turned to Germany for help, where several BMW IV engines were purchased.

First Flight and Limited Service

The first flight of the Paribatra bomber took place on June 23, 1927. Subsequently, two more prototypes were built with Bristol Jupiter and Curtiss D-12 engines. Information regarding the flight tests was not found, but it is known that the Boripatra was produced almost individually, with only 12 units manufactured until 1933.

In the early 1930s, it was replaced by American aircraft from the Vought company. The most important historical event in the aircraft’s life was an official flight to India. In December 1929, two Boripatra aircraft departed from Rangoon for India, returning in late January 1930.

Technical Specifications

Modification	Boripatra
Wingspan, m	13. 41
Length, m	8.7 7
Height, m	3. 20
Normal takeoff weight	1846
Engine type	1 Bristol Jupiter Piston engine
Power, hp	1 x 450
Maximum speed, km/h	253
Cruising speed, km/h	220
Service ceiling, m	6000
Crew, crew members	1
Armament:	two 7.7-mm machine guns, up to 400 kg of bombs