Str^m-Tejsen and Chislett 



Table 1 

 Sequence of Events Controlled by Programming Circuits 



using the Oscil. program. Subsequent integrations of, for instance, the sine 

 component will furthermore have opposite polarity sequences enabling any dif- 

 ferences in positive and negative integration rates to be averaged out. 



The duration of the hold period, in which the desired final value is recorded, 

 is governed by the time lag between the impulses fed to Input 1 and Input 2 of 

 the unit. 



Integration of Forces in Pure Yaw Tests 



Periodic forces resulting from "pure yaw" motions axe processed by the 

 Oscil. program. Figure 16 shows that the angular velocity of the origin of the 

 body axes is out of phase, and angular acceleration is in phase (but of opposite 

 sign) with angular displacement. It is therefore convenient to use displacement 

 as a reference, and the synchronous switch is consequently adjusted to give im- 

 pulses to Input 1 at positions of zero, maximum, and minimum angular displace- 

 ment, i.e., at ojt + ((p/2) = 0, 77/2, TT, 377 2, 277, etc . This is accomplished by 

 rotating the synchronous switch to a position halfway between the angular dis- 

 placement of the forward and aft scotch yokes; i.e., if the forward yoke leads 

 the aft by a phase angle 0, the synchronous switch has a phase angle of ^2. 



338 



