GB803722A - Vertical velocity meter - Google Patents

Abstract

803,722. Measuring rate of climb. SPERRY RAND CORPORATION. Oct. 23, 1956 [Oct. 27, 1955], No. 32324/56. Class 40 (1). In a rate-of-climb indicator operated by integration of vertical acceleration cumulative errors are cancelled out by a signal derived from comparing the integrated accelerometer output with the differentiated output of an altimeter. In Fig. 1, a gyroscope rotor turns about an axis XX in a drum 8 which is eccentrically mounted on axis YY, the drum being balanced by weight 9 and spring 15 to be level when acted upon by gravity alone. Vertical acceleration (positive or negative) causes the drum to tilt about YY and this in turn induces precession of the frame 2 about the vertical axis ZZ. The tilt is detected by brushes 19 bearing on a contact segment 14, and these energize the winding 24 (Fig. 2) of motor 16 which rotates ring 4 in one direction or the other to oppose the precession and maintain the drum level. Stabilization of the whole apparatus is effected by gyroscope repeaters 21, 21<SP>1</SP> acting about the axes X<SP>1</SP>X<SP>1</SP> and Y<SP>1</SP>Y<SP>1</SP> respectively. The slider of potentiometer 28 is thus turned through an amount dependent on the velocity of climb and a signal output 34 (Fig. 2) is obtained from the transformer 92. The barometric altimeter 38 similarly produces an output from the E-type pick-up 32 which is amplified and differentiated in the motorgenerator unit 42, 46. Intermittent response of the altimeter is smoothed out by mechanical feedback through 44 and electrical feedback via 51. The integrated accelerometer output 34 is similarly smoothed in the unit 60 which comprises an amplifier feeding a motor controlling the slider of a mains-energized potentiometer 54. The signal from this is combined with a fraction of the output 34 and applied at 50 to a circuit 76 which is also supplied with the differentiated altimeter output at 48. The difference between the two signals is amplified and passed via 62 to the motor 18 which (Fig. 1) rotates the tilt axis of the drum 8 by an amount which compensates for the cumulative errors. A radio altimeter may be used instead of a barometric altimeter. The errors may be further reduced by introducing into the accelerometer output 34 a portion of the error signal applied to motor 18.