The foreword section was a conventional flat-sided fuselage with an open nose-gunner's position, equipped with a machine gun on a flexible mounting.

Like the centre section it was heavily armoured, with 3 mm (0.12 in) thick walls and a 4–5 mm (0.16–0.20 in) floor providing protection from ground fire at altitudes above 250 m (820 ft) The other three crew positions were in the central section, pilot and mechanic sitting side-by-side in an open cockpit at the leading edge and with a mid-upper gunner or observer, who could also drop bombs, close behind them.

The DB-20's rectangular, high aspect ratio tailplane was mounted on the fin just above the fuselage, braced to it with V-struts and carrying overhung (balanced) elevators.

[1][3] The exact date of the first flight of the DB-20 is not known but it was not long before the beginning of October 1929, flown from Mérignac by Charles Descamps, the Dyle and Bacalan test pilot.

By March 1929, possibly with the armour in place, provisional, unofficial performance figures[2] were well below the theoretical predictions of the previous October,[1] with a speed of 180 km/h (110 mph) and a time to 1,000 m (3,300 ft) of 13 minutes.