Aircraft Production in Thailand
The history and development of aircraft production in Thailand is relatively little known. Since 1915, Thailand has not only built French and American aircraft under license, but also produced some indigenous designs. Among these are the Boripatra two-seat reconnaissance/light bomber biplane, first flown in 1927, as well as the RTAF-5 trainer/ Forward Air Control aircraft, which first flew in 1984. A few civilian aircraft and helicopters have also been built or assembled in Thailand.
The first flight in Thailand, or Siam as the country was known until 1939, took place on January 31, 1911. Impressed by the new invention, and its possible military applications, the Royal Siamese Army sent three officers to France for flying training. The first aeroplanes ordered were four Nieuport monoplanes and four Breguet III biplanes. These were delivered in 1913. The first aircraft built Engineering Section was, in fact, not built to fly. It was a Nieuport monoplane, equipped with stub wings, and only capable of making short hops. As such, it served as an excellent training device, both for novice pilots as well as in the noble art of aircraft construction. The first Siamese built flyable aircraft, a Breguet III, flew for the first time on May 24, 1915. It was built from local woods by the Engineering Section of the Royal Aeronautical Service, and piloted by Lt Col. Luang Sakdi. During the first flight of the Siamese built Breguet on May 24, 1915, Lt Col Sakdi reached an altitude of 300 feet. Sakdi was also the first Siamese pilot, who had received his certificate in France on October 12, 1912. Less than two months prior to the flight, the Army Aviation unit had been reorganized into the Royal Aeronautical Service. Lt Col Sakdi commanded the Air Service between 1914 and 1932. He stressed the Air Service's need to expand and develop, but also to try to be self-reliant. Sakdi later received a Royal title, Phraya, and an official name, Chalerm Akas.
After Siam declared war on Germany, a contingent of troops was in 1918 sent to France. Although some pilots were trained at Pau, no operational sorties were flown. Siamese pilots were part of the French occupation forces in Germany. After the end of the war, a total of 32 French aircraft and 80 surplus engines were purchased and brought back to Siam. Among these were 12 Nieuport 18 and 23 trainers, ten Spad VII and XIII fighters and ten Breguet 14A and B reconnaissance and bomber aircraft. Apparently, ten Nieuport 18 and 23s were built under license in 1921. Thirty SPAD VII and XIII fighters are said to have been produced in 1923 at the Aeronautical workshops. In addition to the aircraft that were produced in Siam, several more Breguet 14s and Spad XIIIs were bought from France in 1922.
In 1922, it was decided to standardize on two types of aircraft, the tried and trusted Breguet 14 and the Nieuport Delage NiD 29C.1 fighter. Ten Breguet 14s, costing 26,700 Baht each, had been bought from France in 1919, with several more following in 1922. It was considered to be a versatile aircraft, being rugged and dependable and well suited to the needs of the Royal Aeronautical Service, which was part of the Army. In 1923, 60 Renault and Hispano Suiza engines had been acquired from France. That the RAS suffered from limited funding is shown by the fact that this purchase alone alone accounted for 30 % of the 1923 budget. The Breguet 14 was of mixed construction, with a tubular steel fuselage and wing frame and wooden wings. It was used as a reconnaissance and bombing aircraft, as well as a mail carrier. The license production of the Breguet 14s and Nieuports began in 1924. To produce aircraft under license was a cheaper option than importing them, partly because of the cheaper labour costs in Siam. France was the main supplier of aircraft to Siam, but was also considered to be a potential military threat to Siam. As well as being cheaper, producing aircraft in Siam was also seen as a sign of self-reliance. Siam was the only country in South East Asia to escape colonialism. Although Siam had a limited industrial base, the country had, since the late 19th century, been adept at bringing parts of western culture and technology and assimilating them into the Siamese society.
All engines, radiators, instruments, as well as raw materials such as duraluminium and steel tubing were all imported from France. Finding suitable woods in Siam, which compared with the European ash, oak and spruce woods proved to be quite difficult. After testing, some indigenous woods were found to have the same qualities regarding strength. The only drawback was that the Siamese woods were heavier, therefore increasing the weight and reducing the performance of the license built aircraft. It is not known with certainty how many Breguet 14s were produced in Siam, but the total probably exceeds the usually quoted 40. Several 14T bis variants were produced as well. This variant was known as the "Sanitaire" and was used to carry passengers, including the odd tourist, and mail. Forty were still in service in 1936, with some aircraft still being utilized as target tugs in 1940. They were, in all probability, the last operational Breguet 14s anywhere in the world.
Two NiD 29C.1s were bought from France for use as pattern aircraft. The NiD 29, at the time the standard French fighter, was a biplane powered by a 300 hp Hispano Suiza liquid-cooled engine. At least 12, but possibly up to 30 were built over a period of several years. The construction of the NiD 29 was more complex than previous types. The semi-monocoque fuselage was built up from plywood. Because of financial constraints, the RAS decided to make its own plywood rather than importing it. Construction of the fighters was a slow process, as it took four or five workers one month to complete one aircraft. By the end of 1924, four Nieuports had been completed, with another eight in various stages of construction. No formal production line per se existed. Instead, each aircraft was virtually hand-built. In theory, eight to ten aircraft could be completed per month, but the actual production rate was much less.
Apart from being heavier than the French built aircraft, the Siamese NiD 29s suffered from excessive engine vibrations at top speed. Presumably, the hot and humid climate must have impaired the Nieuports performance characteristics and serviceablity. The Nieuport was the standard fighter until the introduction of the Curtiss Hawk II in 1934. The NiD 29s saw action during the Bowaradej rebellion in October 1933. They were finally withdrawn from use in 1936.
It had been planned to build large numbers of Breguet 14s and NiD 29s, but these plans were abandoned in late 1927. One of the reasons was a visit to Don Muang on October 29, 1927, by a French Potez 25. The Potez was a modern multi-purpose aircraft, which outperformed the Air Service's Breguet 14s and had a top speed of 150 mph, only five mph less than the NiD 29s. A British report, written later the same year, concluded that the Air Service was equipped with obsolete aircraft, virtually useless for any warlike purposes, made a deep impression on the RAS. As a result, the Air Service would use up existing stocks of Renault and Hispano Suiza engines for its Breguets and Nieuports, but not buy any additional engines nor build any more aircraft of these types.