388 Alex Goodman 
development of a set of desirable handling qualities which could be used in optimizing the 
submerged body design [1], development of methods which give an objective evaluation of 
the submerged body’s dynamic behavior, and improvements in, and development of, new pre- 
diction and experimental techniques which could be used by the designer to evaluate the 
submerged body performance. 
This paper presents and describes the various experimental techniques and methods of 
analysis used at the David Taylor Model Basin in the field of dynamic stability and control 
of submerged bodies. The advantages and disadvantages of the various techniques are pre- 
sented. Primary emphasis is placed on the principles and operation of the DTMB Planar- 
Motion-Mechanism System [2] as well as on the concepts, techniques, and philosophies used 
in simulator and motion analysis studies. Throughout the presentation, it will be noted that 
frequent references will be made to the use of the various techniques as applied to the sub- 
marine stability and control problem. Most of the data acquired by these techniques have 
been for submarines because of the urgency that submarine problems have assumed in recent 
years. It should be noted, however, that these techniques are also applicable to other types 
of marine vehicles. 
COMPARISON OF EXPERIMENTAL TECHNIQUES 
The various approaches to the solution of problems in the field of dynamic stability and 
control of a submerged body moving through a fluid, shown in Fig. 1, have been employed by 
naval architects and aerodynamicists for many years. Many investigators have used the free- 
running or flying-model techniques since a direct evaluation of the performance of the design 
is provided [3,4]. However, this method does not provide data which can be related to the 
physical characteristics of the design or to support the design changes required for improved 
performance. The full-scale technique suffers from the same shortcomings. However, this 
technique is used mainly for providing data for model-full-scale correlation. 
In recent years, the development of general-purpose analog and high-speed digital com- 
puters has resulted in the extensive use of the mathematical-model technique. This tech- 
nique, which is based on a thorough analysis of the differential equations which govern the 
motions, provides a solution and basic understanding of the dynamic stability and control 
problems of a submerged body. However, these differential equations of motion are 
comprised of numerous coefficients or derivatives which are of hydrodynamic origin. 
et FULL-SCALE TESTS Slate 
PROBLEMS THEORETICAL PREDICTIONS 
IN a asa 
PIRICA 
STABILITY pags Me 
AND ify 
CONTROL | CAPTIVE _MODEL [>| MOTION ANALYSIS|C> 
—— FREE FLYING Bie 
MODEL TESTS 
Fig. 1. Approaches to problems in stability and control 
SOLUTIONS 
