Abstract: A compressed gas cartridge is provided that includes a hollow cartridge front section having a male high-pressure gas quick-connect fitting, a forward piston-receiving channel, and a projectile receptacle; a hollow cartridge rear section having a rear piston-receiving channel and a forward valve seat; a center cylinder connected between the cartridge front and rear sections and including an interior gas storage space; and a piston that sealably fits within the front and rear piston-receiving channels. The piston has a solid rearward portion configured with a striking surface and a hollow forward portion. The hollow forward portion has an exterior cylindrical, concentric seal with a rearward edge configured to sealably engage the valve seat. Piston exhaust/fill holes just rearward of the concentric seal allow compressed gas to move between the gas storage space and the hollow interior of the piston forward portion during both discharge and filling.

Abstract: An imaging apparatus 6 has means for illuminating a selected surface with a radar beam footprint, and means for profiling/processing the resultant radar returns in an efficient and logical fashion such as to derive radar attitude information in real time about a number of predefined axes associated with the radar which depends upon the relative dispositions of the radar and the selected surface and upon the radar beam footprint characteristics. Advantageously, a plurality of transmit beams 10,11,12 are used to image the surface and the processing arrangement has the capability of determining roll, pitch and/or yaw pointing data associated with the radar, such pointing data being determined by derivation of the attitude information and by selective input of terrain elevation data so as to take account of variations in the radar viewing geometry with terrain elevation.