186 



SOME GRAPHIC STUDIES OF THE ACTIVE GYRO STABILIZER. 



is obtained when the wave period is shorter than the natural period of the vessel 

 or the pendulum. This is clearly expressed in Figs. 4, 5, 9, 15 and 23, Plates 113 

 and 114. These demonstrate the quenching effect of the stabilizer for wave im- 

 pulses of shorter and also longer phase than that of the pendulum. The close 

 quenching capacity for wave impulses having any period can be had from the main 

 quenching formula by substituting for T the period of the wave. 



The wave impulses chosen for Figs. 9, 13, 16, 22 were really beyond the capac- 

 ity of the stabilizer, resulting, as anticipated, in unquenched roll. This perform- 

 ance stands out in strong contrast with the performance of anti-rolling tanks 

 under similar conditions, which invariably show on both sides of synchronism a 

 marked falling-off of the stabilizing power as expressed by very large unquenched 

 forced roll at these points. As bearing on these points one cannot do better than 

 to refer to Fig. 2 of the extremely able work of Lloyd Woollard in his paper pre- 

 sented before the Institute of Naval Architects in June, 1913. 



In estimating the quenching power of tanks for purposes of comparison, the 

 friction increments caused by any unquenched roll should receive due considera- 

 tion, as these increments act as a powerful aid which has been wholly neglected by 

 some investigators. 



From model experiments with anti-rolling tanks, which were widely pub- 

 lished, the curves. Fig. 24, were obtained under the following conditions, figured 

 roll quenching increments of tanks for synchronous waves: Tank No. i, q= 2.99 

 degrees; tank No. 2, g'= 2.835 degrees; figured from data furnished. The model 

 showed an extinction curve given by Fig. 24. The following deductions can be 

 made: 



These data refer only to synchronous conditions. In cases where the waves 

 are not synchronous the positively controlled gyro stabilizer is in a class by itself. 

 Its lack of any period and mass moment allows it to closely stabilize, at a maximum 

 efficiency, wave moments resulting from any sea, and when the demand upon it is 

 far beyond its capacity it invariably deducts its full decrement from each single 

 roll impulse, and practically without power on the; part of the precession motor, 

 and, moreover, is found to positively operate at increased efficiency under these 

 conditions. 



It will also be found that the weight required for an active gyro stabilizing 



