Around 1930 there was a French interest in small aircraft capable of evacuating a single ill or wounded patient to hospital from roughly prepared sites in the colonies.
This assisted take-off and landing performance, important for short, rough strip operation but required the patient's compartment to be well behind the centre of gravity for easy access, making trimming more difficult.
[1] The Potez 42's fuselage, like the wings built of wood, was constructed around a frame based on four longerons and was flat-sided apart from light, rounded upper decking.
The 89 kW (120 hp) Salmson 9Ac nine-cylinder radial engine appears uncowled in photographs though early diagrams include a narrow chord Townend ring.
The patient's compartment was behind the cockpit, under a one-piece, easily removable fairing which was provided with a forward window on each side and rear air vents.
Its balanced rudder was full, prominent and extended down to the keel and the inset, unbalanced elevators were on forward swept hinges so that the overall horizontal tail was strongly tapered in plan.
[1] In July 1931 Les Amis de l'aviation sanitaire (Friends of Medical Aviation) organised a large meeting on the subject spread over several days, one of which was used for demonstration flights undertaken by nine different types of aircraft.