The RFB Fantrainer is a 1970s-era two-seat flight training aircraft which uses a ducted fan propulsion system. It was manufactured by Rhein-Flugzeugbau GmbH (RFB) in Germany and used by the German and Thai air forces. The Fantrainer sales were few; due to its unorthodox configuration it was not a typical or preferred trainer aircraft for new pilots, and the model was said to be underpowered for the jet performance trainer role it was intended for. However users said it was fuel-efficient and silent and provided an almost "jet feel" for a reasonable price.

Initially the aircraft flew powered by a Wankel engine but finally it was produced in two models, the Fantrainer 400, powered by a 545 shp (406 kW) Allison 250-C20B, and the Fantrainer 600, which was powered by a 650 shp (480 kW) Allison 250-C30. In both, the turboprop engine drives a pusher fan. The wings are swept 6º forward to keep the center of gravity balanced and the four 96-litre capacity fuel deposits are placed inside of them.

First flight for the prototype aircraft took place on October 27, 1977. In August 1982, the Royal Thai Air Force signed a contract with RFB for 47 aircraft, 31 model 400 and 16 model 600. They were assigned to the 402 Squadron and used as a step-up trainer for their future F-5 Freedom Fighter pilots. 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 for the manufacturer.^[1]

In 1986 the Fantrainer was evaluated by the Luftwaffe in an armed configuration but no orders were placed.

Composite fuselage and built up film covered wings.