The RFB Fantrainer (or Fan Trainer) is a two-seat flight training aircraft which uses a mid-mounted ducted fan propulsion system. Developed and manufactured by German aircraft company Rhein-Flugzeugbau GmbH (RFB), it has been used by the Luftwaffe and Royal Thai Air Force. Development of the Fantrainer commenced during the 1970s. In Germany, it was selected as the winner of a competition for the Luftwaffe's Basic Trainer Requirement, having beat both the Pilatus PC-7 and Beechcraft Mentor. However, no orders were forthcoming from Germany as it had committed to buying American fighters (F4 Phantom and F-104 Starfighter) which included a deal for pilot training in the United States. At one point, German flag carrier Lufthansa also reportedly took an interest in the aircraft, noting its jet-like handling. Pilots have confirmed the type to be relatively fuel-efficient and capable of providing a true "jet feel" for a reasonable price. The Royal Thai Air Force operates the FT400 and FT600 versions, using it to train ab initio pilots who then went on to fly the Northrop F-5E fighter aircraft. The RFB Fantrainer is a twin-seat trainer aircraft; its most distinctive feature is its propulsion system, a mid-mounted ducted fan. This reportedly delivers performance akin to aircraft harnessing conventional jet propulsion, but at significantly reduced costs; on average, the Fantrainer has one-tenth of the fuel consumption of the Dassault/Dornier Alpha Jet, a contemporary jet-powered trainer aircraft. Furthermore, RFB has claimed the type to be one-fifth as expensive to procure as the Cessna T-37 Tweet, a rival trainer, while delivering comparable performance (except for a slower top speed) at one-tenth of the fuel consumption. The design of the Fantrainer reportedly incorporates several features to increase effectiveness and reduce costs. Attention was also paid to ease of use, the engine is controlled via a single-lever power control with ground and flight idle stops, behaving much like a traditional turbojet unit; in general, both controls and instrumentation are clear and straightforward. The engine and fan installation incorporates a freely-moving turbine, which necessitates constant-speed control over the fan along with the use of reduction gear to roughly halve the 6,000 rpm output of the engine to achieve a fan speed of 3,090 rpm; both of these were designed by British supplier Dowty Group. The constant speed of the five-bladed fan enables the use of a relatively simple blade profile. Various noise reduction measures were implemented, including the use of Hoffmann-sourced plastic-covered wooden blades and the adoption of a re-designed fan that used five blades instead of seven. The use of a foam-plastic rubbing strip enables the fan to maintain the optimum blade-tip-to-shroud gap, said to be one-thousandth of the fan's diameter according to RFB; the ring slot ensures smooth air flow even at high power and low airspeed, and can also open asymmetrically to cope with offset inflow when the Fantrainer is flown at a relatively high angle of attack. Number built 50. Variants AWI-2 First prototype of the Fantrainer family. First flight in 1977 powered by two 150 shaft horsepower (110 kW) Wankel engines - 300 shaft horsepower (220 kW) in total, changed in 1978 to Allison engine. ATI-2 Second prototype. Fantrainer 400 Stretched fuselage version with metal wings, powered by a 406 kW (545 hp) Allison 250-C20B turboshaft engine. Fantrainer 600 (Speciications below) Improved version, powered by a 485-kW (650-hp) Allison 250-C30 turboshaft engine. Fantrainer 800/1000/1200/1500 Upgraded versions, planned but not produced yet.
