This radical design by ducted-fan protagonists RFB was designed as a two-seat (tandem) jet trainer, offering low operating costs by use of a ducted-fan engine mounted aft of the cabin and fore of the T tail. A rotary engine was considered initially, but the specified Allison type prevailed. The design proved too radical for many and commercial success was not forthcoming. The Fantrainer only saw service in small numbers with the Luftwaffe and the Royal Thai Air Force.

Robert Jackson "The Encyclopedia of Aircraft", 2004