GB146691A - Apparatus for indicating and recording side drift or leeway of aircraft - Google Patents

Abstract

146,691. Tripp, W. H., and Wilkins, C. E. W. May 29, 1919. Measuring-apparatus.-Apparatus for indicating the velocity of drift of aircraft and also the total leeway made comprises an exposed vane 1 mounted, with its plane parallel to the longitudinal axis of the aircraft, on a rod 2 passing through an arm 3 pivoted to arms 4, 4', which are pivoted at 5, 5<1> and carry counterweights 6, 6'. The vane 1 is deflected by transverse air currents, and the resulting motion of the arms 4, 4' is resisted by a cantilever spring 7 mounted between abutments 9, 9<1>, so shaped as to vary the effective length of the spring as it becomes deflected so that the deflection of the spring is proportional to the transverse wind speed. An air dash-pot 10 having a leakage valve 12 is connected by a link 11 to the arm 4', which also has a slot 14, in which works a pin 13 on an arm 15 constrained to move horizontally by slots 16 and pins 17. The arm 15 carries two pawls 19, 19' adapted to operate opposed ratchets 20, 20' secured to a rack 21 engaging with a pinion 25. A pin 27 on the pinion 25 engages a slot 28 in an horizontally movable member 29 having a forked extension 30, to which is secured a pointer 34 moving over a scale 35, Fig. 6, to indicate the velocity of drift. The fork 30 engages in a groove 36, Fig. 10, on the boss 37 of a friction wheel 38 mounted on a squared shaft 39, which is driven at a constant speed by clockwork &c. The wheel 38 drives a pair of cones 43, 43' mounted on parallel shafts 44, 44', to which are secured bevel-wheels 47, 47' driving the members 48, 48' of a differential gear, the spindle 50 of which is secured to a shaft 51 carrying a pointer 52, which thus indicates, in conjunction with a dial 53, the total leeway made. In order that the pointers may not cease to indicate when the velocity of drift has become equal to the transverse velocity of the wind, i.e. when vane 1 has returned to its central position, the ratchets 20, 20<1> are provided with shields 24, 24<1> to prevent the pawls from operating during the return of the arm 15 to its central position.