Abstract: Base bleed unit comprising a surrounding housing (1) surrounding at least one mass flow generating gun powder charge (7), and having at least one outlet hole (6, 6′) extending through a rear wall (3) of the housing (1), in which also at least one igniter charge (4) is arranged. According to the invention, an internal and the rear wall (3) adjacent portion of the mass flow generating gun powder charge (7) is arranged abutting a preferably substantially conically narrowing supporting wall surface extending from the rear wall (3). The preferably substantially conically narrowing supporting wall surface may comprise a centrally located member (5), extending from and integrated with the internal surface of the rear wall (3) of the base bleed unit, arranged to act as a supporting surface with its external surface, or with such a member attached to said internal surface. The preferably substantially conically narrowing wall surface may also comprise a collar shaped member.

Abstract: A base bleed unit arranged to increase the range of fire or to reduce the time of flight for shells and projectiles includes a housing (1) surrounding a fuel charge (6) and associated igniter (4), extending from the rear portion of a projectile body (2) and including at least one outlet nozzle (5,5',5") for combustion gases, which by means of a mass flow, and possibly combustion adjacent to the base plane, reduce existing base drag. According to an embodiment of the invention, the housing (1) comprises a caseshaped member 1 attachable against a projectile body (2), having at least one igniter (4) arranged adjacent to an internal plane of a restricting wall surface at the housing (1), located in an opposed relationship to the portion of the housing (1) attachable against a projectile body (2). The combustion flame of the igniter (4) is hereby maintained directed towards the fuel charge (6) and away from the outlet nozzle/nozzles (5, 5',5").

Abstract: A gun-launched projectile with a chamber for generation of combustion gases from a propellant grain is disclosed. The chamber is arranged with at least one gas outlet in its base plane, said propellant grain having a burning area, mass and static burning rate so related with the area of the gas outlet/outlets, that a low mass flow of gaseous combustion product is operable to continue from the time of muzzle exit for a considerable portion of projectile flight and to provide a substantial decrease in base drag with a concomitant increase in projectile range. The pressure in the combustion chamber during flight only slightly exceeds the base pressure in an amount of 0.01 to 0.5 bar.