Patent GB-191513617-A (GB)
Title: Improvements in or relating to Range-finding Apparatus.
Inventor: HOOPER JAMES GEORGE
IPC: G01C3/00
Filed: 1915-09-24
Abstract: 13,617. Hooper, J. G., and Hobley, F. R. Sept. 24. [Cognate Applications, 4412/16 and 5790/16.] Sights and methods of sighting.-Relates to range finders for aerial targets, and consists in providing two sighting- devices at the ends of a long home base line connected electrically to miniature searchlights so that these move synchronously with the sighting devices and the intersection of their beams on a calibrated translucent screen situated at the gun station gives the range. The sighting-devices, Fig. 1, comprise a telescope A provided with a ring A<5> and a sight-hole A<6> to constitute a finder and rotatable about two axes A<1>, A<2> at rightangles to one another. A switch arm C is connected to the telescope so as to rotate therewith, and carries contacts C', C<2>, C<3>, C<4> adapted to engage conducting rings D<4>, D<5> and a resistance D mounted on a disk A<3> supported on ,a rotatable sleeve A'. A disk E, mounted on the sleeve A<7>, carrries switch arms E<3>, E<4> contacting with conducting rings E', E<2> and two sets of triple resistance studs F mounted on the base A<4>. Three equidistant tappings are taken from the resistance ring D and are connected by wires to three brushes d<1>, d<2>, d<3> which bear on slip rings el, e<2>, e' carried upon a fixed pillar A<8> mounted on the base. The light projector B, Fig. 2, is mounted on a permanent magnet H pivoted to rotate about a horizontal axis B' and carried on a table B<4> pivoted to rotate about the vertical axis B<2>. The table B<4> supports a drum G upon which are three coils G<1>, G<2>, G<3> connected together to form with the magnet H a rotary field device. The table is carried upon a spindle J<2> upon which is also mounted a drum J provided with three coils adapted to revolve within the embrace of a permanent magnet K and constituting a second rotary field device. In operation, a battery is permanently connected across the rings E<1>, E<2> which are also connected to the rings D<4>, D<5>, and current thus passes through the resistances F, D from which three equidistant tappings are made and connected respectively through brushes N' and slip rings N to the three coils on the drum J, and through brushes L<1> and slip rings L to the coils on the drum G. Thus the search-light B moves in union with the telescope A. The locating arm P, Fig. 4, is carried by a rod P<4> pivoted on a pin P<5>, and the whole is pivoted about a vertical axis P<1>. The arm P carries a translucent screen P<3> on which are marked three scales, the scale S to indicate the distance of any point upon it from the axis P<2> and the scales S, S<2> graduated with correcting factors for the timing of a fuse and for the elevation of a gun. A slide R co-operates with the scale S' and is connected by a pivoted rod R<1> to an extension Q<2>, and a slide R<2>, of which the lower end engages by means of a pin with a cam slot Q<3>, co-operates with the slide S<2>. A quadrant Q<1> gives the angular elevation. In the modification shown in Fig. 5 the frame P carries two lengths of resistances T, T<1>, or two series of studs connected to a sub-divided resistance the opposite ends of which are crossconnected. Three equidistant tappings are taken from the resistances and connected to a rotary field device U. A cursor W is adapted to slide on the frame P and to impress an electro-motive force selectively on the circuit T, T' so that the indicator moves according to the position of the cursor. Resistances V, V<1> may be inserted for correcting the fuse timing for different elevations, the slide R having a contact R<3> and the cursor a contact W<1> for co-operating therewith. The atmosphere in the neighbourhood of the beams may be charged with smoke. Instead of inserting correcting resistances, the corrections may be effected by short-circuiting sections of the main resistance. According to Provisional Specification 13,617/15, the movements of the lightprojectors may be effected by cords passing over pulleys, each cord being connected to a spring at one end and at the other to the oores or armatures of solenoids connected to the rheostats of the sighting devices, or in place of a spring a second solenoid may be used. According to Provisional Specification 5790/16, the resistances in the vertical ring of contacts of the sighting-device may, instead of giving a uniform resistance gradient, be so selected as to impart to the search-light a movement about the horizontal axis so as to correct the elevation indicated for the gun.