During 1927, following the success of his M 18 airliner tried to gain funding from the Baverian government; because the latter were already subsiding BFW (Bayerische Flugzeug-Werke) they pressed for an arrangement whereby Willy Messerschmitt joined BFW on the understanding the company produced only his designs. During these negotiations, completed on 8 September 1927, the Ministry of Transport put pressure on Messerschmitt to produce military aircraft. This led to the only two biplanes Messerschmitt ever designed, the first of which was the BFW M.21, otherwise known as the Messerschmitt M 21.
It was a two-seat single-engined trainer of single bay biplane layout..The wings, which folded for transport had parallel chord, no sweep and very little stagger and there were ailerons on both planes. The upper wing had a rounded cut out for improved visibility from the rear cockpit; the forward cockpit was under the wing. The fuselage was square sided with triangular upper decking behind the open cockpits and it tapered to the rear, making the generous fin and rudder appear even more prominent. A conventional single axle plus tail skid undercarriage was fitted.
Type a Two-seat trainer and sportplane b  Two-seat trainer and sportplane
Engine 1 Sh 11 1 Sh 12
Dimensions Length 7.32 m, height 2.82 m, span 10.0 m, wingarea 20.8 m2 Length 7.22 m, height 2.82 m, span 10.0 m, wingarea 20.8 m2
Weights Empty 460 kg, flying weight 740 kg Empty 480 kg, flying weight 740 kg
Performance Max. speed 145 km/h at sea level, cruising speed 130 km/h, climb to 1000 m 9 min. 30 sec., landing speed 75 km/h, range 600 km, service ceiling 3400 m, runway for take off 80 m Max. speed 156 km/h at sea level, cruising speed 140 km/h, climb to 1000 m 7 min, landing speed 75 km/h, range 600 km, service ceiling 3800 m, runway for take off 70 m
Type Werk.Nr Registration History
a 417 D-1566 First flight 17/8 1928. To DVS GmbH Febr. 1929. Destroyed Dec. 1933
b 416 D-1568 First flight in Sept. 1928. To DVS GmbH Febr. 1929. To DVL e.V. Adlershof. Scrapped Oct. 1936