The Dyle et Bacalan DB-70 was a large three engine French airliner with a thick airfoil centre section which accommodated the passengers.

In 1925 the large naval ship builders Société Anonyme de Travaux Dyle et Bacalan, established in 1879 and based in Bordeaux,[3] developed an aircraft manufacturing interest.

The centre section also mounted the three 450 kW (600 hp) Hispano-Suiza water-cooled inline engines and the pilots' cockpit and enclosed the passenger accommodation.

The centre engine was mounted on the central frame, positioned well forward of both the leading edge and of the planes of the two outer propellers.

Aft of this central area were toilets, a kitchen and baggage space plus corridor access to a floor trapdoor which was the principal passenger entryway.

A 'promenade' ran the width of the centre section ahead of the seating areas, lit by glazed wing leading edges, with further passenger access doors at either end.

Adjacent to it in the centre section leading edge was a corridor that allowed the third crew member, a mechanic, to enter the engine compartments for in-flight servicing.