Apparatus for the mechanical solution of trigonometrical problems

摘要

299,138. Addison, H., and Luard, W. B. Aug. 24, 1927. Addition to 264,755. Plane-trigonometry calculators. - The instrument of the parent Specification is modified to enable it to be used with observations made on a moving object such as a ship. In the form shown in the Figure, and in addition to the two air course arms d, q and cursors e, r and the ground course arm d2 and cursor s, there is a " ship " course arm y with cursor z, this arm being pivoted at the centre of the base a. Connected with the cursor z is a degree scale a1 coaxial with a " wind " arm m having a cursor l linked by a pantograph t and a telescopic link or blade g with the cursors e, r, s. In the use of the instrument the arm d and cursor z are set in accordance with the ship's course and speed and then clamped. The arms d, d2 and their cursors are next positioned to represent the speed vectors of the aircraft on two different courses. With the central pivot of the pantograph engaged with the ground speed cursor s the wind arm and cursor l are now manipulated until the link g makes the observed drift angle (relative to ship) on the graduated sector e', the wind vector thus being obtained. The wind arm and cursor may now be clamped and the scale a1 bodily shifted until eccentric with the base, the pantograph meanwhile being free of the cursor s. Arm d2 and cursor s are then moved until the pantograph may again be engaged with the cursor, whereupon the arm and cursor give the true ground speed. In place of a pin and slot connection at s1 an optical aligning means may be provided. Specification 273,198 also is referred to.