SOME GRAPHIC STUDIES OF THE ACTIVE GYRO STABILIZER. 



By Elmer A. Sperry, Esq., Member. 

 [Read at the twenty-first general meeting of the Society of Naval Architects and Marine Engineers, held in 



New York, December 11 and 12, 1913.] 



The present wide interest in stabilizing ships and the large amount of study 

 recently given this subject has led us to some extended studies to secure further 

 experimental data and records of actual performance under varying conditions. In 

 this connection some of the tests have been made parallel to some of the later work 

 done by others, so that comparisons can readily be made. 



The experimental apparatus consisted of a cycloid-pendulum in the form of 

 a rigid platform on which an active gyro stabilizer and its control were mounted 

 provided with an upper extension and lower shelf for accommodating the weights 

 required to establish any desired characteristics in pendulic height, period, and 

 total weight. This, structure rested on two %-inch diameter steel rods on steel 

 plates and could roll thereon. It carried on one end a horizontal running board 

 or track on which a weight, chiefly in the form of a heavy iron roller, could 

 perform reciprocating motions symmetrically with respect to the axis of the pen- 

 dulum; this was positively reciprocated by a motor-driven crank acting through 

 a very long, light connecting rod. 



The weight itself, the period of its motion, and the crank radius were ad- 

 justable, thus providing for the exertion of sinuous moments closely correspond- 

 ing to those exerted by a series of regular waves of definite slope and period on 

 a floating body. The motion of the moving weight deviated only very slightly 

 from the ideal owing to the connecting rod being about twenty times the crank 

 radius and although the motion of the pendulum was somewhat different from 

 that of a vessel amongst waves, in certain vertical components these may be neg- 

 lected and the results as expressed by the records are essentially correct for the 

 reason that the gyros are not affected by any but angular motion. 



The recorder consisted of a constant-speed, motor-driven drum. The re- 

 cording pencil derived its motion directly from the pendulum itself by means of 

 a long connecting rod. 



The active stabilizer consisted of two small gyros coupled for opposite pre- 

 cession on their vertical axis by means of a locking worm drive, the worm shaft 

 was driven by magnetic clutches, operated by an automatic control, from either 

 of two discs rotated in opposite directions at a predetermined and comparatively 

 low speed by a small shunt- wound motor. In their center position the spinning 



