RFB Fantrainer The RFB Fantrainer is a two - seat flight training aircraft which uses a mid mounted ducted fan propulsion system . It was developed by Rhein - Flugzeugbau GmbH ( RFB ) in Germany in the late 1970s and used by the German and Thai air forces . It won a competition in Germany beating the Pilatus PC - 7 and Beechcraft Mentor as the best solution to the Luftwaffe ' s Basic Trainer Requirement . However , no orders were forthcoming as Germany had committed to buying US Fighters ( F4 Phantom and F - 104 Starfighter ) which included a deal for pilot training in the USA . Lufthansa was also interested in the aircraft due to its jet - like handling . Users said it was fuel - efficient and silent and provided a true " jet feel " for a reasonable price . In conjunction with the intended new production of the Fantrainer , initiated by the Fanjet Aviation GmbH in Germany , the Fantrainer 600 was renamed as " Fanjet 600 " . Design and development . The German company Rhein Flugzeugbau developed an interest in aircraft powered by ducted fans integrated into the fuselage in the 1960s , flying two modified gliders as testbeds in 1969 and 1971 . In 1970 it announced a new project for a two - seat ducted - fan military trainer , intended to offer jet - like handling at low cost . In March 1975 , RFB received a contract from the German Defence Ministry for two prototype Fantrainers for evaluation as replacements for Piaggio P . 149 s used as initial trainers by the " Luftwaffe " . The first prototype ( registration " D - EATJ " ) , powered by two NSU Wankel engine s , made its maiden flight on October 27 , 1977 . This engine installation proved troublesome , and the second prototype ( " D - EATI " ) , fitted with a single Allison 250 - C20B turboshaft engine , flew on May 31 , 1978 . The second prototype crashed on September 7 , 1978 , which resulted in the first prototype being modified to Fantrainer 400 standard , with an Allison engine and revised air intakes . The Fantrainer was evaluated by the " Luftwaffe " against the Beechcraft T - 34C and Pilatus PC - 7 turboprop powered trainers , but although it was considered to be the most suitable of the three aircraft , being cheaper both to purchase ( at DM 1 million per aircraft ) and to operate , no orders resulted as it was decided that the Piaggio P . 149 was still adequate for the " Luftwaffe " s needs . The aircraft was finally produced in two models , the Fantrainer 400 , powered by a Allison 250 - C20B , and the Fantrainer 600 , which was powered by a Allison 250 - C30 . In both , the turboprop engine drives a pusher fan . The wings are swept 6° forward to keep the center of gravity balanced and the four 96 - litre capacity fuel cells are integral with the wing structure . In August 1982 , the Royal Thai Air Force signed a contract with RFB to buy 47 aircraft , 31 of the model 400 and 16 of the 600 . They were assigned to the 402 Squadron and used as a step - up trainer for their future F - 5 Freedom Fighter pilots . The step - up characteristic of the Fantrainer generally covers one of its main advantages . The training ability for pilots through a Fantrainer is almost fully covered and only supplemented by an Advanced Trainer for the purpose of getting a high performance jet training and experience . The first two aircraft were built in Germany , and the remaining aircraft were assembled in Thailand from kits shipped from RFB . After an initial period of operation , the RTAF elected to replace the aircraft ' s glass fiber wings with locally - produced aluminium wings , even when the original fiber glass wings proved to endure well in the hot and humid Thailand weather , which was a main concern of the manufacturer . In 1986 the Fantrainer was again evaluated by the Luftwaffe in an armed configuration and as a jet trainer but no orders were placed . The end of the cold war simultaneously displayed the termination of the alpha jet program . The alpha jet used to be a light attack aircraft as well as an advanced jet trainer to that time , used by pilots in their succeeding training phase after their initial training by the Fantrainer . The Fanjet Aviation GmbH bought the documentation for the design - , test - and certification of the Fantrainer 600 . Furthermore , the company acquired the trademarks of “ RFB , Rhein - Flugzeugbau " and “ VFW , Vereinigte Flugtechnische Werke " . The Fantrainer 600 today operates under the name “ Fanjet 600 ” . Variants . Ranger 2000 . In the early 1990s RFB and Rockwell International developed in a joint venture a jet - powered variation of the Fantrainer under the denomination Ranger 2000 , which was evaluated as a trainer aircraft in the JPATS contest by the USAF and the U . S . Navy , but no orders were placed as the aircraft lost to the T - 6 Texan II . One of the two prototypes crashed during evaluation . The Ranger 2000 ' s turbofan engine was a Pratt & Whitney Canada JT15D .