In October 1920 Latécoère won a contract to build a four-engined biplane to meet the French requirement for a machine in category BP3.

It was a single bay biplane, the sesquiplane arrangement requiring the simple parallel inter-plane struts, streamlined and wide, to lean heavily outwards.

The duralumin internal structure was complicated but based on double I section spars, nine in the upper wing and six in the lower.

The geodetic structure was essentially two helices, one right-handed and the other left, joined at each intersection so making a continuous network.

[2] Forward of the trailing edge, the fuselage deepened rapidly, creating a little balcony from which a gunner could cover attacks from behind and below.

The pilot sat with his head at the wing leading edge and in front of him the fuselage fell rapidly away to another gunner's position in the extreme nose.

[1] The engines, initially four 260 hp (190 kW) Salmson Z9 water-cooled radials were wing mounted in tractor-pusher pairs driving four-blade propellers.

[1] The water-cooled engine, with its radiator behind the propeller allowed neat, tight and well streamlined cowlings, mounted above the lower wing on a series of short struts.