Propulsive Effects of a Rotating Mass 



Fig. 25 - Oscillograph of the per- 

 formance of the device indicated in 

 Fig. 9 



abscissa we have the angle of rotation e of the motor shaft and in the ordinate 

 N, the voltage v and the current i, measured on the terminals of the motor. 

 In order to pass from the input power VI to that measured on the shaft in Eq. 

 (4), it was necessary to remove from vi the power absorbed by all the passive 

 resistances and to multiply the power that remained by the efficiency of the 

 motor. The power absorbed by the passive resistance was 9 watts. 



For 0=0 and for = 27t we have v = 26 v, i = 0.46 amp, and vi = 

 11.96 w. The corresponding power on the device is 2.96 w. 



In the points (9=0 and fi^ = 2?^ we have N = 1.42/sec and at the maxi- 

 mum 2.22/sec. The mean value measured by a tachy meter during the test was 

 N = 95/min = 1.58/sec. The corresponding period is T = 0.6316/sec. 



With this value of T, Eq. (7) gives E = 0.1828 kg-m. Having had in the 

 device R = 0.20 m, r = 0.15 m, p = 0.200 kg, and h = 2.15, it was possible 

 to calculate with Eq. (6) the angular speed w. In Fig. 26 the values of u> ob- 

 tained during the test are indicated with (+), and those calculated with Eq. (6) 

 are indicated with (o) . 



We wanted to see the contribution given by pz and by 1/2 Jw^ to the values 

 of E and of w. In Eq. (6), placing pz = produces a curve indicated by (•)» 

 and placing h = gives the curve indicated by (A). The values of E are 

 0.1666 1^-m in the first case, and 0.0927 kg-m in the second. 



For R = r, h = 0, 6* = 180°, from Eq. (6) we obtain oj = ». 



1391 



