The Guillemin JG.40 was designed and built to meet a French government requirement for a small air ambulance capable of operating in the colonies.

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.

They posed several design challenges, principally around the need for a large, clear patient enclosure with easy ground access from a stretcher.

A cockpit well behind the trailing edge allowed the patient's compartment to be placed over the centre of gravity, where varying loads would least affect the trim.

The wings were trapezoidal in plan and were in three parts, with a centre-section mounted on top of the fuselage and slightly hollowed out above to improve the field of view from the cockpit.

The metal door to this space was hinged from below and had telescopic stays which held it horizontal when open, easing the move from stretcher to the adjustable bed within.

The JG.40 had fixed landing gear, with split axles and drag struts hinged from the central fuselage underside and with vertical Messier oleo-legs from the forward wing spars.

[14] Despite its excellent test results the Guillemin JG.40 did not reach production and the small air-ambulance role was filled by the later and more powerful Bloch MB.81.