GB738488A - Improvements in or relating to calculating apparatus for use in air navigation - Google Patents

Abstract

738,488. Calculating-apparatus. BAKKE, A. BLOM-. Jan. 18, 1952 [Jan. 19, 1951], No. 1455/52. Class 106 (1). Apparatus for solving vector triangles for use in aerial navigation comprises a " ground speed " bar 3 pivoted to a " wind speed " bar 2, an " air speed " bar 4 adjustable in length and pivoted at one end to a cursor 6 slidable on the bar 2 and connected also to a cursor 5 slidable on the bar 3, and a graduated dial 1 pivoted to the bars 2 and 3 measure the angle between them and enable the apparatus to be orientated on a map. The bar 3 carries a speed scale 13 and an altitude scale (not shown) for co-operation with a temperature scale on a stretchable band 17 which also bears an indicated air-speed scale and a time scale 19. In use the band 17 is stretched until the graduations on the temperature and altitude scales corresponding with the ambient temperature and attitude of the aircraft, coincide. The band is then locked in this position by means not described and the cursor 5 is moved to align an index mark 8 with the graduation on the band 17 corresponding with the indicated air speed. The cursor 5, which carries a pivot moving in a longitudinal slot in the bar 4, is thus positioned according to the true air speed and with the cursor 6 in zero position, a locking device 15 is operated which prevents relative displacement of the bar 4 and cursor 5 but_permits pivotal movement. The apparatus is then placed on a map, the bar 3 being aligned with the course it is desired to follow and parallel lines on the dial 1 being arranged in the N-S direction. The bar 2 is then set by means of the dial 1 according to the wind direction, and the cursor 6 is set by means of a scale 16 according to the wind speed. During the latter movement, the cursor 5 moves along the bar 3. The ground speed is then indicated on the scale 13 against the index 8 and the course to be steered is found by adding the reading on the dial 1 against the index 9 and the angle of drift indicated by a scale 22 on the cursor 5. The time scale 19 is calibrated according to the scale of the map and is stretched until an index 11 on it is aligned with the index 8 indicating the ground speed. The time taken to travel between two places on the course may then be measured by the scale 19 or the position reached at any time may be found. In order to increase the range of the apparatus, the cursor 5 may be turned through 180 degrees.