Patent GB-145810-A (GB)
Title: Improvements in bomb-sighting and course-steering apparatus for use with aeroplanes and the like
IPC: F41G3/24
Filed: 1918-09-02
Abstract: 145,810. May, W. J. Sept. 2, 1918. Sights.-Relates to bomb-dropping sights for aircraft of the kind in which a vector triangle is set up by means of links representing speed through the air, speed overland, and speed of the wind, and consists (1) in a device comprising an air-speed bar slidable in a base, a wind-speed bar slidably and pivotally mounted on the air-speed bar, a ground-speed bar pivoted to the wind-speed bar and slidably mounted on the base over the centre of two or more adjustable graduated disks on one of which a course-indicating pointer is mounted, gearing being provided to enable the disk carrying the pointer and the wind-speed bar to be rotated through equal angles; (2) in combining with said device a backsight carried above the centre of the disks by a graduated height member adjustably mounted on the base, and a foresight situated at the pivot joining the wind-speed bar to the ground-speed bar; (3) in employing an air-speed scale showing height variations, and a height scale adapted to correct for lag in releasing bombs. In the form shown, the apparatus is mounted on a base 1 carried on a ball-and-socket joint 2 on the frame of the aircraft, means being provided to maintain the air-speed bar 6 parallel to the fore and aft axis of the machine. This bar is slidably mounted in a clip 4 in the base, its position being adjustable in relation to a fixed air-speed scale 8 bearing a series of height lines parallel to the bar 6 crossed obliquely by airspeed graphs. The wind-speed bar 32 is slidably mounted in a clip 30 pivoted on the end of the bar 6, and to it is pivoted at 35 the ground-speed bar 34, the zeros of the two speed scales coinciding with the axis of the pivot. The bar 34 is of V- section, and is adapted to slide in a swivel guide 36 loosely mounted on a vertical spindle located in the base 1, above the air-speed bar 6. On this spindle is mounted to rotate therewith a pointer 17 and a disk 18 carrying a compass card and a 24-hour clock-face. Round the spindle is mounted a second disk 12 carrying an adjustable ring 15 graduated in degrees reading anti-clockwise, and adapted to be set in any position with respect to a fixed mark on the base 1 in accordance with the direction of the wind. The disk 18 and the wind-speed bar 6 are rotatable by bevel gearing from a shaft 23 mounted parallel to the bar 6 and operable by a hand-wheel 26. Slidably mounted on the base 1 is a height member 38 carrying a backsight vertically above the centre of the disks 12, 18 and adapted to be elevated by turning a milled head 41. This member carries two scales, one for use in determining ground distances, and the other for use in bombdropping comprising helical graduations adapted to be read off against one of a set of marks on a fixed collar 42 each representing a certain lag in releasing bombs. The ground-speed bar has a forked extension 49 for picking up objects on the ground and a fixed foresight 48. To set the course of the aircraft when the speed and direction of the wind are known, the disk 12 is set to the direction of the wind, the bar 6 is set by the scale 8 to the normal speed of the aircraft, and the bar 32 to the speed of the wind, and the arm 34 is set by manipulating the hand-wheel 26 to the bearing, indicated on the disk 18, of the required course. The pointer 17 then indicates on the scale 15 the course to be steered. In use as a bombing sight, the course is set as described, and the member 38 is set to the height of the aircraft. When the objective comes in sight it will, if the course setting is accurate, appear to travel between the arms of the fork 49, and the bomb is released when the objective comes into alinement with the sights 47, 48. Any inaccuracy in the course-setting may be corrected by adjusting the bar 34 and steering on the new course indicated by the pointer 17. Reference has been directed by the Comptroller to Specification 177,549.