Patent GB-405107-A (GB)
Title: Improvements in range finders or like instruments for determining fire-control data
IPC: F41G5/20
Filed: 1933-01-16
Abstract: 405,107. Range-finders &c. MONTAUTI, F., 7, Via Ricasoli, Livorno, Italy. Jan. 16, 1933, No. 1383. [Class 97 (i).] An instrument for use on a ship &c. for determining the range of an observed ship and the angle between the course of the said ship and the vertical plane of sight comprises two sections which are set by two observers. In one section the range is determined, using the known or estimated height of the target as a distant base ; this range is introduced into the second section, which has means for measuring the horizontal angle subtended by the known or estimated length of the ship, the desired direction of the target's course being obtained mechanically from the said known length and the measured subtense and range. A scale may also be provided for indicating the torpedo launching angle, this angle being obtained from the ascertained direction of the target's course and the ratio between the speed of the torpedo and the speed of the target. The instrument has two eyepieces A B one for each observer, and each associated with an optical system for measuring the angle subtended by a distant base, the base being vertical in one case and horizontal in the other. The light-entrance prisms 20, 21 are secured to a shaft 64 which can be rotated by turning a knob 1 to annul the effects of rolling, while the instrument can be turned in azimuth to follow the target by rotating a knob 2. The known height of the target is set up in the range-finding section by rotating a knob 3 which operates a shaft 24 on which are worms 25, 27 gearing with wormwheels 26, 28 the wheel 26 being integral with a height scale 26<1>, and the wheel 28 being integral with the wheel 28<1> of a differential D1. For determining the range the hand-wheel 5 is turned, causing, through the gearing shown in Fig. 4, rotation of a worm-wheel 37 carrying a cam 38 which operates a slide 39 carrying half lenses 40, 41 associated with fixed half lenses 401, 411. These lenses produce two images of the target which are relatively displaced in the vertical direction and the wheel 5 is adjusted until the top of one image of, e.g. a mast coincides with the bottom of the other image. The shaft 30<1> carries a worm 34 engaging a worm-wheel 35 rigidly connected to the spider 29 of the differential D1, and the wheel 31 of the differential is connected by gearing to a spindle 33<1> carrying the range-indicating dial 6. To introduce the range into the second part of the instrument, the wheel 31 is connected to the spindle 42 carrying the wheel 42<1> of a differential D2, the spider 43 of which is connected to a worm-wheel 44 rotated by a worm 45 on a shaft 46 which is rotated by a hand-wheel 9 to determine the horizontal angle subtended by the target. The shaft 46 rotates a worm-wheel 66 carrying a cam 67 bearing on a slide carrying the half lenses 69, 70. The wheel 47 of the differential D2 is geared to the wheel 50 of a differential D3 so that this wheel receives a rotation depending on the range and on the horizontal angle subtended by the target. The wheel 51 is rotated according to the known length of the target by means of a knob 7 which also rotates a drum 8 bearing a scale of lengths. The spider 58 of the differential D3 thus receives a rotation depending upon the angle between the target's course and the plane of sight, this rotation being transmitted to a pointer 11 reading against a fixed scale of angles 10. To find the torpedo launching angle additional scales 12, 13 are provided, the latter being fixed and bearing a scale of torpedo speeds, while the scale 12, which can be rotated by a knob 14, has on its outer edge a scale of target speeds and on its inner edge a scale of launching angles. This scale is rotated until the estimated target speed is read against the known torpedo speed on the scale 13. The pointer 11 then shows the launching angle on the inner edge of the scale 12.