Patent GB-422234-A (GB)
Title: Improvements in director fire control systems for naval ordnance
IPC: F41G5/14
Filed: 1933-11-01
Abstract: 422,234. Director gun fire control. THURSTON, A. P., 329, High Holborn, London.- (Ford Instrument Co., Inc. ; Rawson Street. Long Island City, New York, U.S.A.) Nov. 1, 1933, No. 30318. [Class 92 (ii)] Relates to director fire-control systems for naval anti-aircraft or other guns mounted on unstable platforms in which the angles of elevation and training transmitted from the director sight to the guns are corrected for angular movements of the guns relatively to a stable plane. According to the invention, the angle of sight A, Fig. 4, the level angle L, and the cross-level angle Z, Fig. 5, are measured with respect to the stable plane, and from these angles are computed and transmitted to the guns the corrected angles of elevation and training considered with respect to the unstable deck of the ship. Fig. 1 shows gimbal-ring means for stabilizing with respect to a horizontal plane the mounting ring 12 for the elevating and training director sights 17, 18 which are supported from the ring by pillars 14, 15. The ring 12 which is the inner gimbal ring is trunnioned at 13 in an outer ring 10 itself trunnioned at 11 in supports 8, 9 upstanding from a trainable table 2. Training movement is given to the sights by rotating a handle 5 and is shown on a dial 61 being passed by a shaft 69 to the computing apparatus. Elevation is given to the sights by rotating a handle 20 which moves the sights by shafts 23, 25, 27, 30 and gearing 32, 33. The elevation angle (A) shown on a dial 55 is added algebraically by a differential gear 65 to the level angle (L) shown on a dial 49 and obtained by operating a handle 37 to level the ring 12 and keep the horizon in view of the levelling telescope 34. The resultant angle (Es) shown on a dial 75 is conveyed to the computing apparatus by a shaft 80. The cross-level angle (Z) shown on a dial 53 is obtained by operating a handle 42 to cross-level the ring 10 and keep the horizon in view of the telescope 36, the angle Z being conveyed to the computing apparatus by a shaft 99. In place of manual control by handles 37, 42, a gyroscope 337 connected through hunting switches 341, 350 to motors 346, 354 may be employed for maintaining a stable horizontal plane. The computing apparatus receives the corrected elevation Es, Fig. 4, the sight depression angle Us, the corrected elevation Ev or (Es +Us), the crosslevel angle Z, Fig. 5, and the sight deflection angle Ds and computes the correction UD to the sight depression angle and the corrected sight deflection angle DD, Fig. 6. For this purpose the computing apparatus, (not shown), calculates the following approximate formulae deduced from spherical trigonometry tan DD =1/cosEv (KZ sin Ev + K1Ds) and UD= K2 cos Ev{K3 sin Ev (sec DD-K3)-K4ZDs} where K, K1, K2, K3, K4 are constants. The angle DD is added by means of a differential gear in the computor to the bearing angle Bs received by the shaft 69 and operates a training transmitter connected with a similar receiver at the gun which actuates a hunting switch to control the gun-training motor. Similarly, the angle UD in the computor is combined with the angle Ev to operate an elevating transmitter connected with a receiver at the gun which controls the gun-elevating motor.