Messerschmitt M 21

The Messerschmitt M 21, also called the BFW M.21, was a two-seat, single-engined biplane trainer of single-bay layout, designed by Willy Messerschmitt for the German Ministry of Transport. It was one of only two biplanes Messerschmitt ever designed, and neither reached production. The design came out of the agreement of 8 September 1927 under which Messerschmitt joined BFW, when the Ministry of Transport pressed him to produce military aircraft. It had folding parallel-chord wings with ailerons on both planes, a square-sided fuselage and an uncowled radial engine driving a two-bladed propeller, either a 96 hp Siemens Sh 11 in the M.21a or a 125 hp Sh 12 in the M.21b. It first flew in 1928 but was not accepted for production, so only one was built. That aircraft, registered D-1566, flew until 1933 with DVS GmbH, the German sport flying association.