Vehicle Dynamics Associated with Submarine Rescue 



The most significant meter displays are those of doppler 

 velocity, attitude rates. The doppler sonar, located 8.9 feet aft of 

 the C.G. and 3.3 feet below the centerline, provides 3 axis ground 

 velocity data. Since the doppler sonar is offset from the center of 

 gravity, angular motions couple into the doppler signals, and in 

 some situations were interpreted by the pilot as translation veloc- 

 ities. 



Displays were also provided for roll, pitch and heading angles, 

 and for sonar altitude above the DISSUB. Current magnitude and 

 direction indicators were available, but were not used in the simu- 

 lation, since the corresponding sensors were not Installed In the 

 vehicle. The additional displays shown In Fig. 26 are associated 

 with the anchors and haul down winch control systems. 



Shock Mitigation System 



The shock mitigation system serves a dual purpose in the 

 nating operation. The primary one Is that of dissipating the kinetic 

 energy of the DSRV when It lands on the DISSUB. The second function 

 was realized only aiter the simulation study was started. Prior to 

 dewaterlng, the DSRV Is connected to the DISSUB primarily by vertl- 

 Ccil thrust forces fromi the DSRV and coulomb friction. Because of 

 the existence of the shock mitigation system It Is not necessary for 

 the DSRV to land precisely on target. As long as the shock mitigation 

 ring encloses all the staples, the DSRV can slide on the DISSUB deck 

 until precise alignment is reached. 



As described previously the shock mitigation system has been 

 simulated as four Independent damped springs. The natural frequency 

 of the DSRV-shock mitigation system Is approximately 11 radians per 

 second, which Is too high to simulate with a 62. 5 millisecond Iteration 

 Interval, Accordingly, the spring constant was reduced, with a re- 

 duction In the natural frequency to 1 . 7 radians per second. The 

 damiplng constant was also reduced to maintain essentially the same 

 percentage damping. 



Anchor and Hauldown 



Exploratory runs were made using both the anchors and haul- 

 down as mating aids. No help was obtained with the anchors, and 

 very limited assistance was obtained from the hauldown. Schedule 

 and budget limitations did not permit an Intensive evaluation of this 

 problem at the time. Some digital simulation was performed at a 

 later date with the hauldown system, which Indicated that It should 

 provide substantial assistance, particularly when the DSRV Is re- 

 quired to naate bow dp to the current. These results were confirmed 

 on simulated tests nnade with LASS. 



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