Patent GB-506947-A (GB)
Title: Improvements in or relating to calculating apparatus for use with listening apparatus
IPC: F41G5/12
Filed: 1938-03-25
Abstract: 506,947. Calculating-apparatus. TEPAS, KOMANDITNI SPOLECNOST HARLAS A SPOL. V PRAZE. March 25, 1938, No. 9196. Convention date, March 25, 1937. [Class 106 (i)] A calculating device for use with a sound-locating apparatus for ascertaining the future coordinates of an aircraft moving at a constant height and uniform speed in a straight line comprises means for determining the corrections to be applied to a searchlight or gun for any desired working time. The function of the correcting device is to determine the angular co-ordinates of the point F, Fig. 1, assuming that the listening apparatus N is ready to communicate the co-ordinates to the searchlight or gun, at the moment that the aircraft has reached the position G. In the diagram the lead triangle NAF is reduced to the triangle NHI by dividing the side NA by a factor representing the sum of the time t + working time W. The side NI is represented by r and is given by the equation r = c/1 + ZSin#A where C = the velocity of sound, #A=the elevation angle and Z is a value representing the product of the working time by the velocity of sound c and divided by h the height of the aircraft. The azimuthal lead ## is determined from the horizontal triangle NH, I, where Sin ## = v/r1 Sin(#A + ##)and r1 = r Cos #A. For determination of the elevational lead ## the point H is projected on to the vertical plane passing through the line NA to produce the triangle NIHo. This triangle is further reduced by dividing by r so as to produce the similar triangle NKMo wherein If the value v Cos(#A + ##/2) is represented by D and 1/Cos ##/2 is represented by 1À007 the equation becomes p/r = D/r x 1À007. In the embodiment shown in Fig. 8, the dog clutches 1, 2 are connected to the sound locating apparatus to enter the azimuth angle #A and the elevation angle TA and the course angle # with respect to the datum line S is entered by a hand wheel 11. The azimuth angle is transmitted to a frosted glass hemisphere 5 and the elevation angle is transmitted to an arm 8 with a pencil 9 which traces a central projection of the path of flight on the hemisphere. By means of the hand wheel 11 the course angle is indicated on the dial 18 and is transmitted to a differential gear 13 which transmits the sum of the angles #A+# =#A to the shaft 15. The shaft 15 carries a hemisphere 10 with a system of great circles one of which is brought into coincidence with the path traced when the equation #A= #A+# is satisfied. The curves for various working times obtained by plotting Z against height h are arranged on a cylinder 121. A hand wheel 126 sets a pointer 123 on a height scale 124 and a hand wheel 120 rotates the cylinder 121 to bring the selected time curve on to the pointer 123 thereby imparting to the shaft 35 a movement proportional to the value Z. The shaft 35 through worm gearing 34 transmits the value Z to an arm 33 thereby displacing a curved guide 30 that is supported by a roller 31. Bearing on the guide 30 is a roller 32 on a toothed rack 25 carried by a sector 23 which is swung through an angle representing the elevation angle by gearing from the clutch 2. By this means the value r is represented by the distance of the roller 32 from the axis o. The value r + #A is transmitted by the wheel 27 and shaft 29 to a pointer 36. To set up the value r on a similar rack mechanism 24, 26 the angle #A is transmitted by gearing 20, 22 to the sector 24 and the hand wheel 41 is manipulated so as to maintain a pointer 37 in coincidence with the pointer 36. The rack 26 carries a roller 44 engaging a slot in a horizontally displaceable slide 45 on a guide 46 carried by screwed spindles 50, 51 which are driven by gearing from a hand wheel 53 in accordance with the velocity v of the aircraft. A spigot 37 on the slide 45 engages a slot in a pivoted member 48 which takes up an inclined position in dependence on the value v/r1 where rl is the horizontal movement of the slide 45 and equals r Cos #A. The member 48 is formed with a cam that sets, through level geared arms a curved member 59 that is supported on a fixed edge. A rack 62 is carried on a swingable support, the support is adjusted by a cam 66 and is controlled by a differential gear 67 and gears 68, 69 in accordance with the values (#A + ##), and the rack 62 is controlled by the shaft 71 to bring the point 61 into coincidence with the curve 59. The shaft 70 through differential gears 76, 81 transmits the values #A + ## and #A+##/2 to an indicator 80 and a disc 84 respectively. The disc carries a screwed spindle with a nut 88 that can be adjusted to the value v. The nut engages the slotted end of a slide 91 which is displaced in accordance with the value D. The slide 91 has rack teeth engaging a pinion 95 that is displaceable an amount representing the value r and the movement of the pinion is imparted to a rack 96 with a pin engaging a slotted arm 98. The arm 98 sets a pointer 100 and a second pointer 101 is brought into coincidence therewith by operatingahand wheel 107, driving gear 106, rack 105 and arm 103. The rack 105 carries a bracket 113 with a lever 114 pivotally mounted at the point Mo while a lever 116 pivoted at a fixed point is rotated in accordance with the angle #A to form the triangle NKMo. A wheel 112 rigidly connected with the lever 114 gears with a rack 111 operatively connected to a scale 109 which by the means described is turned through and angle #F +p/r . The angle #F is given on the scale since the indicator 108 is set by the handle 107 to the value p/r. Specification 396,715, [Group XXXVIII], is referred to.