GB150813A - Improvements in or relating to course and distance calculators and the like - Google Patents

Abstract

150,813. Stevens, W. J. June 6, 1919. Plane-trigonometry calculators.-A course and distance calculator for aerial navigation problems comprises a circular tray a with bearing and compass graduation on which is pivoted a disk b having a squared grid with an arrow on one diameter. On the pivot works a pair of disks c, d, the former carrying a radius graduated for air speed, the latter for wind speed and having holes to facilitate manipulation. On the edge of the outer tray two brackets r slide by means of gripping-pieces x, x<1>, and in them are mounted spring drums s connected by a thread t. The thread passes through a guiding-slit in the brackets r. Setting is made by bringing the arrow on the grid and the wind radius to the known bearings, bringing the thread through the wind-strength graduation and parallel to the arrow diameter of the grid, and then swinging the air-speed arm till the machine speed comes on to the thread, the machine-speed radius being then on the course bearing. The pivot is in two parts, one e carrying the disks a and grid disk b, and the other i screwing into it, carrying the machine-speed disk c loose on it, and having in a recess a circular plate m attached to the wind disk and screwed to a bolt o against the head of which a friction spring is tensioned. A dished spring g and washer h and a corrugated spring washer j separate the disk c from those on either side of it. The apparatus is preferably made of transparent celluloid so as to be used with maps.