sentences:  In the 1960s the German company Rhein Flugzeugbau developed an interest in aircraft powered by ducted fans integrated into the fuselage, flying a pair of modified gliders as flying testbeds in 1969 and 1971.During 1970, the company announced that it had embarked upon a new project to develop a two-seat ducted-fan military trainer, intending to offer an aircraft that possessed jet-like handling at a low cost.In March 1975, RFB received a contract from the German Defence Ministry to produce and fly a pair of prototype Fantrainers; these would be evaluated as replacements for "Luftwaffe"'s existing fleet of Piaggio P.149 initial trainers.