Flight, February 1932

A New French Night Bomber
The "All-wing" type of Aircraft visualised by Professor Junkers many years ago has not yet materialised, but several attempts have been made from time to time to secure some of the advantages by having a central body deep enough to house most of the load carried, and of sufficient area to act as a lifting surface. The Burnelli machines are a case in point, and now the French Company Societe Aerienne Bordelaise of Bordeaux has produced a night bomber incorporating somewhat similar principles

   DEVELOPED from the Dyle et Bacalan D.B.70 commercial machine by the Societe Aerienne Bordelaise of Bordeaux, the A.B.20 shown in the accompanying illustration is a night bomber fitted with four Lorraine "Courlis" engines of 600 h.p. each, giving the machine a total power of 2,400 h.p. The design is unusual, in that the central portion of the wing has been greatly thickened to give space for crew, bomb load, fuel tanks, etc. In this respect the A.B.20 resembles somewhat the American Burnelli machines, which represent a compromise between the "all-wing" machine and the more orthodox types.
   The A.B.20 was actually begun as a three-engined machine, like its prototype the D.B.70, but the French technical services then decided that they would like the central forward part of the body to be capable of taking a gunner's cockpit, and the design was subsequently modified into a four-engined type, the engines being placed abreast, two in the noses of the fuselages, and the other two in faired nacelles in the leading edge of the wings. One result of thus "changing horses in mid-stream" has been that the machine has come out heavier than expected - to the extent of about 1,000 lb. - but if another machine is built the designers are confident that they will be able to save this weight.
   The A.B.20 is of all-metal construction, and has a gross weight of some 13,500 kg. (29,700 lb.). The central body has large bomb accommodation - at least up to a total bomb load of 2,500 kg. {5,500 lb.). Normally it is intended that the machine should have a range of 600 miles, when the bomb load is about 4,400 lb. The forward part of the central body is built out as a cabin for the navigator and bomber, and in the upper part of it is a gunner's cockpit with swivelling gun ring, etc. Farther aft, and also on top of the central body, is another gunner's position, while a third is situated underneath the body in a sort of gun turret, which can be raised and lowered.
   The wing span of the A.B.20 is 37 m. (121 ft.), and the wing area 206 m2. (2,220 sq. ft.). Of this the central body has an area of 947 sq. ft. The estimated top speed is 215 km./h. (133 m.p.h.), and the cruising speed 195 km./h. (120 m.p.h.). This is at an altitude of 11,500 ft. The theoretical ceiling is 21,300 ft.