Prototype missile

For our performance studies we use the air-to – air missile, introduced as SRAAM5 in Chapter 9 and SRAAM6 in Chapter 10. It is a 6-in. diam/116 in. long, high fineness ratio, body-tail configuration with a 6:1 ogive, blunted for an IR dome with 1.5-in. radius, and forward strakes (see Fig. 11.7). Its forebody includes an imaging IR seeker, electronics, an INS, a cooling bottle, an active optical target detector, and a 20-lb warhead with an electronic safe and arm system.

The SRAAM is modeled in the CADAC environment. It consists of five – and six-DoF fly-out versions and can be obtained from the CADAC CD. The target is modeled as a point-mass vehicle with its attitude aligned in the load factor plane. The maneuvers are defined before missile launch.

Fig. 11.7 SRAAM.

SRAAM5 represents the so-called pseudo-five-DoF implementations as pre­sented in Sec. 9.3.2. Three translational DoF are modeled by nonlinear differential equations (Newton’s equations) employing tabulated trimmed aerodynamic data. The two attitude degrees of freedom are pitch and yaw (skid-to-turn). They are modeled by linearized differential equations that describe the attitude dynamics of the controlled airframe. In this case Euler’s equations are not modeled.

The SRAAM6 version is a full six-DoF simulation. It solves the three trans­lational DoF with Newton’s equations and the three attitude degrees of freedom with Euler’s equations. All systems of the missile are modeled in detail.

During the missile design phase, C ADAC is executed in the batch mode. Its many postprocessing tools support the performance evaluation of the missile concepts. The same missile simulation can be stripped of all unnecessary subroutines using the converter program CONVRT. EXE, which generates a self-contained subrou­tine suitable for real-time execution. Thus, the tractability of the missile simulation from batch processing to execution in the combat simulator is maintained.

The six-DoF architecture of the batch simulation is shown in Fig. 10.53. Each module represents a major subsystem with its closely controlled interfaces. The calling sequence is important and must be maintained for the simulation. For real­time applications the two modules G1 Target and S2 AI Radar are deleted and are replaced by inputs from the flight simulator.

The five-DoF simulation, presented in Fig. 9.54, was built from the six-DoF simulation by simplifying the aerodynamics and replacing Euler’s equations by the response of the attitude autopilots.