<p>c/n 91-201
Built as a Saab 91B Safir with the Swedish military serial Fv50001. Exported to Japan in 1953 as a candidate new training aircraft type for the JASDF. This role was taken by the T-34 Mentor and the Safir was civil registered as JA3055 and used on passenger flights. 
In 1956 it was purchased by the Technical Research &amp; Development Institute (TRDI) and modified as a high lift research aircraft with the serial TX-7101. Research carried out with TX-7101 was used during the design of the Kawasaki C-1, Shin Meiwa PS-1 and Mitsubishi MU-2 
The various trials ended in 1962 and TX-7101, now designated as the X1G1B, flew as a support aircraft until 1986. It went on display when the museum opened in 1996.
Gifu-Kakamigahara Air and Space Museum 
Kakamigahara City, 
Gifu Prefecture, Japan
15th March 2019
</p><p>The following details on the X1G1B are from the excellent j-hangarspace.jp website:-
</p><p>“The Saab 91 Safir that provided the basis of the X1G1B high-lift research aircraft was a well-known type of training/liaison aircraft that had first flown in 1945. A total of 323 were produced in Sweden and the Netherlands and exported to a number of countries. Differing in terms of engine and equipment fit, the sub-types ranged from the Saab 91A to the 91D.
</p><p>In May 1953, the then National Safety Agency imported as a candidate primary training aircraft a Saab 91B (c/n 91-201) that had already seen military service as the first Royal Swedish Air Force Sk50b from July to November 1952. Registered to Asahi Airlines Co. as JA3055, the aircraft was based at Fujisawa airfield, Kanagawa Prefecture.
</p><p>In March 1956, the Beech T-34A Mentor having long since been adopted as the JASDF trainer, the aircraft was purchased for 6.8 million yen by the Technical Research &amp; Development Institute (TRDI, since 2015 the Acquisition, Technology and Logistics Agency) of the then Japan Defense Agency (today the Ministry of Defense) and gained a new lease of life in the testing of high-lift devices. At that time, the aircraft’s previous registration (JA3055) was cancelled and the TRDI provided with the serial TX-7101 in April 1956.
</p><p>Facilitated by the lack of fuel tanks in the wings, the aircraft took on a number of different guises. Given the basic designation X1G—standing for experimental first aircraft Giken (the abbreviation for TRDI)—as the X1G1 the aircraft was fitted with a newly designed, Japanese-built main wing that featured full-span flaps and spoilers. In the cockpit, it was presumably at this time that a flap position indicator was added on a central pedestal. Work to confirm the wing’s effectiveness, including flight testing, commenced in December 1957 and ended in August the following year.
</p><p>From April 1959 to September 1960, the now X1G2 was fitted with a 260 hp Continental engine in place of the original 190 hp Lycoming to cope with the extra weight from having a gas turbine installed, complete with a large exhaust, in its fuselage (link). The gas turbine formed part of an experimental boundary layer control system designed to increase lift by blowing high-pressure air over the upper surfaces of the wings and flaps via devices fitted to the leading and trailing edge of the main wings. Formerly of fabric, the skins of the rudder and elevators were changed to metal. During 1960, the aircraft was flown from Chofu airfield in Tokyo.
</p><p>As the X1G3 from April to August 1962, attempts were made to solve the problem of high-lift device controllability by suppressing wingtip vortices. The distinctive feature of this modification was the addition of rectangular end plates to the wings.
</p><p>In late 1962, its career in research having come to an end, the now four-seater aircraft was used for liaison purposes, again fitted with the X1G1 main wing but designated X1G1B as the Continental engine was retained. Following its withdrawal from service in 1986, the aircraft was stored within the TRDI’s Gifu test area. The aircraft has been on indoor display at Kakamigahara since the then aerospace museum (now Gifu-Kakamigahara Air and Space Museum) opened its doors in 1996.
</p>
As the know-how and technologies gained from the tests carried out on this aircraft were utilized in designing the C-1 transport, the PS-1 flying boat and the MU-2 business aircraft, its contribution to the development of Japan’s aviation technologies was enormous. The technology by which high-pressure air is blown over the upper surfaces of the flaps in particular has been continued, via the UF-XS experimental amphibian, through to the latest US-2 amphibian. Other than maintenance needed on parts of its external paintwork that had deteriorated over time, the aircraft needed no work carried out at the time of its addition to the museum collection. Well preserved in the condition it was when in operational use, including traces of its time as a research aircraft, its cultural value remains high.”
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/65001151@N03">Alan Wilson</a> from Peterborough, Cambs, UK
CC BY-SA 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/ajw1970/48192236082/">Saab 91 X1G1B ‘TX-7101’</a>