49.2 x 26.71 x 8.45mm
3d printed in Grey
The SAB AB-20 was a four-engine night bomber development of the three-engine Dyle et Bacalan DB-70 airliner. The change of manufacturer's name was the result of the financial failure of Dyle et Bacalan in 1929, followed by its immediate reappearance as SAB, who took over DB-70 development. The latter was built around a thick, wide chord airfoil centre section which provided generous internal space for passengers. The engines were mounted on this structure as were twin fuselages to carry the tail. The outer wings were of normal thickness and chord, and the cockpit and undercarriage were also attached to the centre section. The generous intra-wing volume equally offered crew, fuel and bomb-room for military purposes. Initially the AB-20 was intended to have three engines like its predecessor, but during the design phase there was a military request for a bombardier's position and a gunner's cockpit in the nose, which required the removal of the centre engine and its replacement by two extra engines wing-mounted outboard of the centre section.
Apart from the extra engines and the very different crew compartment, together with the removal of passenger accommodation, the AB-20 and DB-70 had much in common: the thick centre section and high-mounted outer wings, twin fuselages carrying a long horizontal stabilizer, and twin fins and rudders. Both aircraft had conventional undercarriages with pairs of mainwheels widely separated on V-struts attached to the lower longerons of the centre section.
The new central crew pod was flat-sided and tapered forwards to a complicated cylindrical nose, formed by a simple lower part with an overhanging, windowed cabin for the navigator/bombardier and an open gunner's cockpit, fitted with a machine gun ring, directly above. The nose also carried a long, conical probe with fine extensions, possibly pressure sensors. Further aft there was an enclosed pilot's cabin. A second gunner was stationed rearwards, on top of the centre section and a third fired from a ventral turret.