118 THE DEVELOPMENT OF WEAPONS SYSTEM REQUIREMENTS 



angular velocity, and range rate along the line-of-sight. This information is 

 utilized in conjunction with aircraft flight data (speed, altitude, etc.) to 

 compute an attack course that permits the weapons to be launched with a 

 high kill probability (see Paragraph 1-4 and Figs. 1-3 and 1-4). Deviations 

 between the computed attack course and the actual interceptor flight path 

 are presented to the pilot as a steering error signal. The pilot — -or auto- 

 pilot — flies the aircraft to reduce the steering error to within the limits 

 required by the weapon characteristics. 



Guided Missile Launching Zone Parameters. The allowable 

 launching ranges and angular error launching tolerances for the inter- 

 ceptor's guided missile may be obtained from a graphical representation of 

 the launching problem. This analogue model — shown schematically in 

 Fig. 2-41 — utilizes the fixed parameters of the target, interceptor, and 



Launch Point 



fn 



,Maximum-G Missile Trajectory 



-Maximum Missile 

 Range Envelope 



Fig. 2-41 Graphical Determination of Launching Zones. 



guided missile as defined in Figs. 2-5 to 2-7. The launching tolerances 

 calculated from this model represent the permissible deviations from perfect 

 solutions to the fire-control problem. 



We may construct and employ this model to analyze the problem in the 

 following manner: 



STEP 1 . A value of range to impact point that lies between the maximum 

 and minimum missile downranges is chosen. A semicircle with 

 a radius equal to this range is drawn around the impact point. 



STEP 2. The missile time of flight corresponding to the chosen down- 

 range is read from the missile performance diagram. The target 

 position at weapon launch can then be plotted P^rff units back 

 of the impact point. 



