Patent GB-344549-A (GB)
Title: Improvements in calculating mechanism particularly for use in training guns
IPC: F41G11/00
Filed: 1929-12-16
Abstract: 344,549. Calculating-apparatus. ALGRAIN, P., 16, Rue Albert, Laeken, Belgium. Dec. 16. 1929, No. 38514. [Class 106 (i).] Gunnery calculators.-An apparatus particularly for training anti-aircraft guns comprises means for ascertaining, by extrapolation, the variation to which a function has been subjected during an extrapolation interval known to have elapsed. For this purpose an index controlled by the variation cooperates with a pointer which is moved, by the operator, to the position which the index will occupy at the end of the extrapolation interval. In the form shown in Figs. 1, 2, and 3, for extrapolating the angle of elevation of a moving target, an index 2 is provided with a rack 2c operatively connected through intermediate gearing with a rotatable cylinder 4a adapted to be driven in one direction by ratchet wheels and differential gearing 41 .. 44, Fig. 4, from the training handle V. The intermediate gearing comprises a plurality of gears 21a, 22a .. 2na and corresponding pinions such as 21b. Each pinion 21b is mounted on an arm 21d and is provided with a return spring 21r, and each gear wheel 21a is provided with a pin 21c which acts upon an arm 2b and operates the pinion 2a. The initial position of the wheels 21a &c. is determined by a stop arm 3b. These mechanisms are arranged for successive engagement and the time elapsing between the successive engagements is greater by a few seconds than the longest phase of engagement. The engaging and disengaging movement is effected by the rotation of cylinders 5e, 5d. The shaft 5 is driven at a constant speed and rotates the cylinder 5e directly, whereas the cylinder 5d is rotated indirectly through a differential gear 5a the relative position of the cylinder 5d being adjustable with respect to cylinder 5e by the operation of an interval-controlling handle M so as to regulate the time of engagement. The cylinder 5e carries pins 51e, 52e, .. which co-operate with corresponding pawls 51b to release, at regular intervals, the arms 21d which are urged to engaging position by springs 51r. The disengaging is effected by pins 51d, 52d acting on the arms 21d to restore them to inoperative position being engaged by the pawls 51b. In practice the pinion 2a is formed as a bevel wheel 2a<1>, Fig. 3, and an elongated pinion geared therewith operates the rack 2c of the pointer which is carried in a slide 2d displaceable by means of rack gearing from the control handle M. The index 2 cooperates with a record-strip driven directly from the shaft 5. The predicted or future position is recorded by a second marking element or pointer 7, Fig. 3, operated by gearing connected with a handle E. The handle E as shown in Fig. 4 is adapted, through gearing, to actuate pointers 7a, 7b, cooperating with a graduated drum 4t and fixed pointer 4r to give an indication of the extrapolated value. The drum 4t is driven through gearing connected with the training handle V. A mechanism for disengaging the arms 21d &c. in the event of an incorrect operation is provided comprising a shaft 6a to which is secured a rod 6t, Fig. 1, and an arm 6l, Fig. 6. Rotation of the shaft 6a to cause the rod 6t to raise the arms 21d &c. is under the control of a spring 61 and pawl 6c. This pawl is connected to a lever 62a adapted to be oscillated by the arm 2b of the wheel 2a when said arm passes its extreme position. The arms 21d &c. may be disengaged by hand by means of a pin La on an arm L freely mounted on the shaft 6a. Means are also provided for adjusting the initial position of the arm 3b under the control of gearing connected with the handle E. In use two observers continually ascertain the elevation and height of the target and obtain from a firing chart, automatically adjusted by these settings, the time of flight of a projectile i.e. the extrapolation interval. The handle V adjusted by the first observer rotates the roller 4a and the drum 4t proportionally to the elevation angle and a third observer sets the interval handle M in accordance with the time as given by the chart. A fourth observer manipulates the handle E in order to bring the extrapolation pointer 7 in the prolongation of the curve formed by the pointer 2 and to adjust the pointers 7a, 7b the displacement of one or other of which gives an indication of the variation in the function, viz. the angle of elevation, under observation from which the range can be determined.