60 THE DEVELOPMENT OF WEAPONS SYSTEM REQUIREMENTS 



All of the other unknown parameters (subsystem variables) affect one 

 or more of these three basic weapons system variables. This observation 

 makes it possible to organize the study plan on a step-by-step basis as 

 follows : 



Step I: Construct a model of the overall weapons system using the three 

 primary weapons system variables as adjustable parameters. Assume 

 values for each of these adjustable parameters and calculate the resulting 

 system performance. Compare this performance with the desired level of 

 mission accomplishment; use any discrepancy between the two to adjust 

 parameter values for another tentative design. Testing of the model 

 continues until the following information is derived. 



1. All combinations of the adjustable weapons system parameter 

 values that will allow achievement of the mission accomplishment 

 goal. 



2. The sensitivity of system performance to changes in the values of 

 the adjustable parameters. 



Additional information — useful for obtaining a good understanding of the 

 overall problem — is obtained by ascertaining the sensitivity of system 

 performance to changes in the fixed elements. 



Step 2: Assume fixed values for the three weapons system variables of 

 Step 1 that permit the system to achieve the desired level of mission 

 accomplishm.ent. Construct a model (or models) which expresses the 

 relationships between the adjustable (unknown) AEW parameters (beam 

 width, information rate, radar detection range, etc.) and the assumed 

 weapon system parameters. Test this model for various assumed combina- 

 tions of AEW parameters. Establish acceptable combinations of AEW 

 parameter values and the sensitivity of system performance to parameter 

 changes. Derive a specific set of AEW requirements. 



Step 3: Using the values for the unknown system variables derived in 

 Step 1 and 2, repeat Step 2 for the adjustable parameters of the interceptor 

 weapons system. Derive a specific set of requirements for the AI radar and 

 fire-control system. The suggested order of Steps 2 and 3 is somewhat 

 arbitrary; a reasonable case might be made for reversing this order. As a 

 general rule, where a choice exists, it is wise to select an order which places 

 the most difficult subsystems first, since this will maximize the number of 

 adjustable parameters available for its preliminary design. 



2-8 MODEL PARAMETERS 



The interrelations between major system parameters and the contribu- 

 tions of each parameter to overall effectiveness may be developed through 



