Sahreihev 3 Bentkowsky and Kerr 



Fig. 26. Ins-trument Panel 



ELEMENTS OF SIMULATION 



Vehicle 



Because the mating operation is confined to low current 

 velocities , vehicle control is obtained by means of the main propul- 

 sion and thrusters; the shroud remaining locked amidships. The 

 relatively limited capability of the Ambilog computer necessitated 

 some approximations of the equations of motion to assure fitting 

 the entire problem to the computer. The major approximation used 

 Ignored the stalling effect of the shroud. 



The effect of this approximation is shown in the comparison 

 of the heave versus angle of attack curves of the analysis and simu- 

 lation models of Fig. 27. At high angles of attack the simulation 

 model provides higher heave forces than the analysis model, an 

 effect which tends to make the results of the simulation conservative, 



The iteration interval used in the computation was 125 milli- 

 seconds. Since some of the degrees of freedona, particularly the 

 mating aids, require a higher frequency response, selected portions 

 of the simulation utilized a 62.5 millisecond interval. A relatively 

 simple integration routine was employed, as shown in Fig. 28. 



1168 



