Improvements in devices for measuring the speed of aerial targets for purposes of anti-aircraft fire control

摘要

378,603. Determining speed of aerial objects. NAAMLOOZE VENNOOTSCHAP NEDERLANDSCHE INSTRUMENTEN-COMPAGNIE, 44, Javastraat, The Hague.-(Assignees of Bergh, S. J. vanden; 17, Josef IsraÙlslaan, The Hague.) June 26, 1931, No. 18496. Convention date, July 3, 1930. [Class 106 (iii).] Apparatus for determining the speed of an aerial object according to the equation vg= v1 + v2/sin alpha + cos alpha (Fig. 1), is characterized by means by which the apparatus can be maintained in a condition in which (vl + vs) is kept constant assuming the velocity of the target to remain unaltered during temporary invisibility. The shaft 1 driven in known manner according to v and the shaft 2, driven in known manner according to vs cause, through gearing shown, the pointer 37 to indicate on the scale 38 values of (v- + vs and the friction wheel 48 to be displaced on a grooved shaft 46 from the centre of the constant speed motor-driven friction disc 49 a distance corresponding to (vl + vs), thus causing a vertical displacement of the pin 57 from its zero position through a distance corresponding to (vl + v,). The cam disc 65 is rotated by known means according to a and causes, through the engagement with it of the roller 64, a horizontal displacement corresponding to (sin alpha + cos a) in the guides 62, 63 of the frame 61 from a zero position. By these means a vertical displacement of the pin 69 corresponding to vg is obtained causing at the same time a similar vertical displacement of the pencil 74 on a drum 75 driven by clockwork 76. During observations the handle 89 is rotated to rotate the threaded spindle 88 to move the body 85 so that the record of vg on the drum 75 is kept between the forks 90 to cause, through the lever 78, slide 82, cord 93 and spring-controlled annular body 95, the mark 96 to follow the pointer 37. When the target is temporarily obscured the shafts 1, 2 are turned so that the pointer 37 remains coincident with the mark 96 thus causing the pencil 74 to remain in the position it occupied immediately before the target became obscured. If the working of the mark 96 with the slide 82 is disturbed during temporary invisibility of the target, the shafts 1, 2 are turned so that the indication of the pointer 37 on the scale 38 corresponds to the indication of the pointer 91, attached to the slide 82, on the scale 92.