Abstract: Pressure relief holes are sized and positioned on each fin of a projectile to allow high pressure from one side of the fin due to canard and fin interaction to bleed to a low pressure area on the opposite side of the fin. The location of the pressure relief holes target pressure differences due to canard roll control downwash while not affecting pressure differences due to projectile attitude. The fin planform area remains small enough to meet packaging and fire requirements for this type of munition and large enough to aerodynamically stabilize the airframe thereby enabling a more robust pitch and yaw autopilot design.

Abstract: A mortar ammunition round which contains at least three fragment producing regions covered by a threadably removable aluminum cowling. Detachment of the cowling provides access to several of the fragment producing regions which are located on a removable cup device. A different cup device may then be selectively inserted and the cowling replaced, forming a new mortar round of different select performance capabilities.