Patent GB-191101510-A (GB)
Title: Fire Control Apparatus:- An Instrument for Indicating Range, and Rate of Change of Range and for Finding Deflection.
Inventor: BARR ARCHIBALD
Filed: 1911-01-20
Granted: 1912-01-22
Abstract: 1510. Barr, A., and Stroud, W. Jan. 20. Range-finders.-Relates to fire-control instruments for indicating the rate of change of range and the deflexion of a moving target from the direction and speed of the observer's vessel and of the target, and for continuously indicating the actual range of the target. In the diagram, Fig. 3 (which corresponds to the disposition of parts shown in Fig. 2), the velocities of the observer's ship and of the target are represented by CB and CD respectively, so that the relative velocity is represented by BD, and if BA is the line of sight of the target, the components BH, DH along and perpendicular to this line represent the rate of change of range and the deflexion respectively. Apparatus according to the invention comprises a sight-bar to be kept alined on the target, means for setting the known velocities, and means for indicating the required components. The apparatus shown in Fig. 2 is set with the direction BC fore and aft. The sight-bar EF can be trained upon the target either directly or by turning the heads 12, 13. The distance CB is set by turning the head 1 on a rotating screw 2, which traverses a nut 3 carrying a pivot C. A slotted bar 8, upon which is mounted a slider 9 carrying a pivot D, is pivoted at C, so that the distance CD can be set and the pivot and slider clamped. The component-indicating mechanism which is mounted together with the sight-bar upon a frame rotatable about B comprises a rack R<2> pivoted at D to the slider 9 and having connected to it a rack R', the two racks being connected by slides so as always to be at right-angles to each other. Shafts Q<1>, Q<2>, with heads 12, 13 respectively at one end and indicating-means at the other end, have connected to them pinions P<1>, P<2> meshing with the racks R', R<2>. The positions of the pinions R<1>, R<2> upon the racks correspond to the components BH, DH, and are indicated by the indicating-means upon the shafts Q<1>, Q<2>. The distance CD can be set by manipulation of the heads 12, 13 and then clamping the slider 9. Then when the sight-bar EF is trained directly, the pinions and connected indicators are actnated from the racks, or the pinions and indicators are actuated by the heads 12, 13 as these are turned to train the sight-bar. In a modification shown in Fig. 4, the pin D corresponds to the pivot D of Fig. 2 and may be set by similar means. This pin is surrounded by slotted bars 24, 25, the positions of which correspond to the required components BH, DH, and are adjusted by turning the heads 49, 28 on threaded shafts carrying the bars 24, 25 and provided with indicating and transmitting means. Drums 42, 43, 44 for indicating actual range and receiving additions corresponding to the indicated varying rates of change are driven from a friction disk 37 carried by the bar 24 and driven by a clockwork-driven disk 39 at a rate varied to correspond with variations in the rate of change corresponding to the position of the bar 24. The pitch of the thread on the shafts carrying the bars 24, 25 may be coarse enough to allow the sight-bar to be set directly instead of by means of the heads 49, 28.