434 REGULATORY CIRCUITS 



3. By the frequency-response characteristics of the aircraft in yaw, pitch, 

 and roll. This information can also be derived from the equations which 

 describe aircraft dynamics. 



4. By an actual time response made of angular aircraft motions as an 

 ideal attack course is flown. This assumes that an actual aircraft is 

 available or that it can be simulated on an analogue computer and "flown" 

 realistically with an autopilot or human pilot. An ideal, simplified radar 

 and antenna tracking system may be assumed, but noise and approximate 

 error filtering should be included in the simulation. The time responses 

 may be used as follows: 



{a) A Fourier analysis of the time responses may be made. This may 

 be made by conventional methods, but it usually is not as useful in 

 design synthesis as the other techniques are. 



{b) Segments of the time response may be represented by sinusoids 

 or parts of sinusoids of various amplitudes and frequencies. These data 

 are particularly useful in the synthesis of antenna stabilization control 

 loop frequency responses. 



5. By a statistical description of the aircraft motion. This is usually not 

 available, and the effort required to obtain the power density spectrum is 

 considerable. However, motions due to gust disturbances are better 

 described statistically, as discussed in following sections. 



The most useful descriptions of aircraft motion for preliminary stabiliza- 

 tions considerations are given by methods (1), (3), and (4). Typical 

 numerical values of modern interceptor aircraft motion described by these 

 methods are given in the following pages. 



Maximum Disturbances Incident to Aircraft Maneuvers. The 



controlled interceptor motions, as limited by the aerodynamic charac- 

 teristics of the interceptor, which affect the angle tracking system design, 

 are roll and roll rate, yaw and yaw rate, and pitch and pitch rate. Estimates 

 of a typical interceptor's capabilities are: 



(a) ROLL 



Roll angle: +180°, -180° 



Roll rate: 80° /sec to 90° /sec 



(b) YAW 



Oscillation frequency: 3 to 6 rad/sec 

 Sideslip angle: 1-2° 



(c) PITCH 



Pitch angle: +180°, -30° 



Pitch rate : 20° /sec up to 40° /sec 



Pitch frequency: 2-13 rad/sec 



Pitch oscillation angle: Pitch rate /pitch frequency = 1.5° to 10° 



