GB554835A - Improvements in or relating to instruments for the navigation of aircraft - Google Patents

Abstract

554,835. Course-recording apparatus. SMYTH, B. T., and MOORE, M. S., (Representative of MOORE, Q. S.). Jan. 15, 1942, No. 623. [Class 97 (ii)] A course-recording apparatus comprises a rotatable transparent grid plate 1 disposed above a map or chart. Below the map are disposed two endless transparent bands 5, 6 adapted to move at right angles to one another, a source of illumination being arranged to illuminate the map &c. The bands 5, 6 are driven by friction gearings 28, 29 from a spindle 24 which is itself driven by friction gearing 27 from a disc 23 driven by a motor at a speed proportional to that of the aircraft. The friction gearings 28, 29 are adjustable by means of the stems 35, 36 bearing on a rotatable cam 14. The wind speed and direction and the air speed and direction are set by hand, the wind speed &c. being represented by a slotted arm 12 and the air speed &c. by the length and direction of the radius from the centre of the cam to the axis about which the arm 12 can be swung, the third arm 15 representing thereby the ground speed and direction of the aircraft. Variation of this arm 15 is effected by a rotation of the grid plate and results in the movement of the friction gear 27 between the spindle 24 and the driving disc to vary the speed of the bands 5, 6. The grid plate 1 is provided with grid lines which are brought parallel with the track marking 11 the pointer 18 then indicates the true bearing of the aircraft while lines 9, 10 on the bands denote by their intersection the position of the aircraft as it moves along the required track. If the aircraft is steered into another course the grid plate is turned by hand into the required bearing altering the direction of movement of the intersection of the lines 9, 10 to show the position of the aircraft on its new course.