420 Alex Goodman 
multiplication or division of one variable by another, generation of trigonometrical functions, 
generation of nonlinear functions, and discontinuities. 
The various components that comprise the DTMB Motion Analysis and Simulator Facility 
are presented in Figs. 34 to 39. 
A typical computer circuit diagram for a submarine in six degrees of freedom is presented 
in Fig. 34. The various symbols used to represent the various computer components are pre- 
sented in Fig. 34d. These components are interconnected by means of a plug-in patchboard. 
The patchboard, therefore, represents the “mathematical” model of the system. A computer 
is equipment with several patchboards, and therefore one mathematical model can be stored 
while another study is being conducted. 
The DTMB analog computer, shown in Fig. 36, consists of four general purpose com- 
puters, manufactured by the Midcentury Instrumatic Corporation, and one analog computer 
manufactured by the Reeves Instrument Company. This facility presently consists of 168 
operational amplifiers. (The number of operational amplifiers is usually used to express the 
size of a facility.) In addition, auxiliary equipment such as diode function generators, white- 
noise generators, X-Y plotting boards, two 8-channel Sanborn recorders, strip-chart recorders, 
and various instrument displays are available. The present facility will be expanded shortly 
to about 300 operational amplifiers when several new computers are procured. With this ad- 
dition, the facility will be capable of handling, simultaneously, two six-degree-of-freedom 
submarine studies as well as other small problems. 
Studies which involve the human operator as part of the closed loop are performed using 
the submarine simulator facility shown in Figs. 37 and 38. The simulator consists of cube- 
shaped cab (about 7 feet x 7 feet x 7 feet) capable of turning on a single axis equivalent to 
the pitch axis of a submarine. It is hoped that an additional degree of freedom, to simulate 
the rolling motion of the submarine, will be added in the near future. The cab contains two 
control stations, each equipped with an aircraft-type control stick (stick-wheel) and the nec- 
essary display instruments. The motion of the cab is governed by an electrohydraulic servo 
system receiving inputs from the analog computer. A block diagram of this circuit is pre- 
sented in Figs. 34c and 39. 
A comparison of the submarine control cycle with the simulator control cycle, presented 
in Fig. 35, shows that the cab constitutes one link in a complete submarine simulator con- 
trol loop which involves the human operator. The equations of motion set up on the analog 
computer (mathematical model) constitute another link in the control loop. Movement of the 
control stick in the cab produces inputs to the computer which then calculates the resultant 
path of the submarine. The submarine attitude angle, depth, depth error, and plane angles 
are displayed by the instruments and the cab rotates to the computed pitch angle. Simulta- 
neously, a graphical record of the submarine trajectory and other pertinent information is 
recorded by a multichannel recorder. 
The Motion Analysis and Simulator Facility in combination with the concept of the 
definitive maneuver provides a powerful tool for studying the handling qualities of subma- 
rines. Several of the typical definitive maneuvers, shown in Figs. 40 to 43, are performed 
using this facility to provide numerical measures of the inherent characteristics of sub- 
marines. 
The meander maneuver, shown in Fig. 40 provides numerical measures of the dynamic 
stability in the vertical plane; such as, time to damp to one-half amplitude ¢, ,», damping 
ratio c/c,, and damped period. The overshoot maneuver also shown in Fig. 40 provides 
