1-12] CONSTRUCTION AND MANIPULATION OF MODELS 41 



control loop is another. Thus the basic parameters of the model usually 

 take the form of distribution functions. 



Attention is invited to the Operations Research volume^ of this series 

 for a detailed treatment of the theory of probability as applied to weapons 

 system evaluation. 



1-12 CONSTRUCTION AND MANIPULATION OF WEAPONS 

 SYSTEM MODELS 



Before analyzing the structure of a model, let us review some of the 

 peculiar characteristics of a weapons system. 



1. A weapons system is an organization of men and equipment designed 

 for operation and use against specific classes of enemy targets. To carry 

 out its overall function — usually the destruction of the enemy target — 

 it must carry out many complex subfunctions. Each functional activity 

 converts certain quantitative inputs into outputs. The entire weapons 

 system is merely a series — or series-parallel — arrangement of these 

 subfunctions connected in such a manner as to permit achievement of the 

 overall system objective. As an example of a typical organization, an air- 

 to-air intercept system might be characterized by the sequence of opera- 

 tional functions shown in Fig. 1-29. Also shown are the major equip- 

 ments that are involved in the performance of each function. 



The input to the system is an enemy target — the output is the destruc- 

 tion of the enemy target. Similarly, each operational function can be 

 viewed as an input-output device. The subject of input-output relations 

 brings us quite naturally to a consideration of another distinguishing 

 characteristic of a weapons system. 



2. A weapons system is a dynamic or time response system. Both the 

 system inputs and outputs have time variables. This fact makes it neces- 

 sary to treat a weapons system in terms of the time delays that it introduces 

 between the input (enemy target) and the output (action against the 

 enemy target). The likelihood of mission accomplishment usually is 

 strongly dependent upon the ability of the system to respond to an input 

 within a specified period of time. 



Each operational function can contribute to the overall time response 

 characteristic. For example, a finite time is required to process target 

 intelligence and tactical situation information for the purpose of assigning 

 a weapon to the target. Upon being assigned, the interceptor aircraft 

 requires a certain amount of time to take off and fly to the target location, 

 etc. Thus, the concept of partitioning the system into subfunctions — • 



^Grayson Merrill, Harold Greenberg, and Robert H. Helmholz, Operations Research, Arma- 

 ment, Launching (Principles of Guided Missile Design Series), D. Van Nostrand Co., Inc., 

 Princeton, N. J., 1956. 



