Abstract: Golf practice apparatus utilizing a tethered golf ball wherein the kinetic energy is dissipated when the ball is struck. Initial velocity vectors in the x, y, and z coordinates are derived by time integrating the respective forces over the period of time during which the kinetic energy is dissipated. From these derived velocity vectors is computed what the trajectory of the golf ball would have been if it had been untethered. Alternatively, two of the initial velocity vectors may be derived as described above and the third obtained mathematically after first deriving total initial velocity. Golf ball spin about a vertical axis may be obtained for correction to the trajectory by means of a reflective strip on the ground facing surface of the golf club head and two or more sensors for detecting the reflections from opposite ends of the strip.

Abstract: An optical sighting system for aiming the main operative axis of an apparatus in the direction of a distant target wherein the sighting system includes an optical sighting device fixed to the apparatus and laterally offset from the main axis of the apparatus and a reticle projector fixed to the apparatus and projecting a reticle image into the sighting device along a path parallel to said main operative axis, various embodiments being disclosed including additional features whereby the sighting device is supported on an arm which is separate from another arm coupled to mount a device for directing the projected reticle image into the optical sighting device, the directing device comprising a mirror or a polygonal prism.

Abstract: A mobile tower supporting a radar antenna system including a drive system and position resolvers, the antenna system being mounted at the top of a cylindrical telescopable mast which is hinge mounted on a tripod base and is erected to a vertical operative position by an hydraulic ram which also retracts the mast to a substantially horizontal position for transport or servicing by personnel standing on a pallet supported by the base, the tower further including tilt and twist monitors having outputs coupled to a computer together with the outputs of the position resolvers to provide a corrected readout of azimuth and elevation angles of tracked targets.