2-9] 



SYSTEM EFFECTIVENESS MODELS 



65 



^t3 



20 40 60 80 100 120 



NUMBER OF INTERCEPTORS ENGAGING 



TARGETS 



1.2 1.0 0.8 



TARGET SPEED, M 



0.6 



80 



£g 60 



li 40 



p20 







200 250 



AEW RANGE (n.mi.) 



300 



2 4 6 8 10 12 



INTERCEPTOR SPEED, M 



Fig. 2-13 Sensitivity of System Effectiveness to Number of Interceptors, AEW 

 Range, and Interceptor Kill Probability Po- 



model becomes the limiting factor. This limitation might indicate that a 

 trade-off of parameter values elsewhere in the problem should be examined 

 to exploit the potential advantage which might accrue from a range 

 increase.^ Conversely, a 50-n.mi. decrease in early warning range would 

 require that interceptor kill probability be increased to 0.70 — a value that 

 is almost equal to the kill probability of the missile salvo alone — in order 

 to maintain the system effectiveness required. 



Increases in target velocity have much the same effect as decreases in 

 early warning range. If the target velocity were to increase by 10 per cent, 

 only 34 interceptions could be made. Thus, to maintain the same defense 

 level under these conditions, interceptor kill probability would have to be 

 raised to 0.58 or early warning range would have to be increased by about 

 30 n.mi. Increases in interceptor velocity have the same general effect as 

 increases in early warning range; i.e., aircraft availability limits the useful- 

 ness of such increases. System sensitivity to this change is relatively small, 

 however, for extremely high interceptor speeds. 



The time delays defined for the model made no allowance for any time 

 delay introduced by the vectoring process. The assumption is that the 

 vectoring system guides each interceptor on a straight-line path to the 



^For example, we might explore the possibility of using the other CAP aircraft which were 

 assumed to maintain their stations. 



