The Sergant A was a French 4-cylinder, air-cooled, upright inline piston engine with a maximum output of 7.5 kW (10 hp), designed to meet the needs of the very small and light single seat sports aircraft of the early 1920s.
In both the UK and France in the early 1920s there was a wish to make civilian flying more affordable, both in capital outlay and in running costs.
It was on display at the November 1923 Paris Salon and struck Flight's reporter as "extremely interesting" and car-engine like in its four-cylinder inline arrangement, a little heavy but reliable.
It was unusual in its high maximum crankshaft speed of 3,200 rpm and the availability of a choice of reduction gear ratios.
[1] The date of first running is not known but it appeared, and was widely used by a variety of aircraft and in several contests during 1923, with more in 1924.