A solid propellant charge for a propulsion unit (1). The latter includes a casing (2) containing the solid propellant charge (3), in the form of an elongated body having a longitudinal axis (X--X), which charge (3) has, over part of its longitudinal extent, a propellant charge profile (4) of large combustion area and is subdivided, along the longitudinal axis (X--X), into at least two segments abutting one another with their respective mutually confronting faces. The propulsion unit furthermore includes a nozzle (5) and means (6) for igniting said charge. The propellant charge profile (4) of large combustion area is provided in that part of the propellant charge (3) which is intermediate along the longitudinal axis (X--X).