Simulink Modeling of Fighter Aircraft Longitudinal Motion: Pitch Rate Control

The purpose is to use Simulink to simulate a (much simplified) model of the longitudinal motion of a fighter aircraft. The 'angle of attack' is the angle between the direction a plane is pointing, and the direction in which it actually moves through the air. For a plane flying at approximately constant altitude, this is equivalent to the 'pitch angle', as illustrated in Fig. 3. This angle is important because it produces a lift force perpendicular to the axis of the plane, and hence a 'normal acceleration', (also shown in the figure).

The pilot wants to be able to control the pitch angle, and does so ultimately by rotating the front fins, and tail elevators of the aircraft, shown in Fig. 4. The first task is therefore to model the effect of these movements on the 'pitch rate', where

b. Pitch Rate, q The rate at which the pitch angle changes, (the 'pitch rate', q), is determined mainly by the angle of the front fins of the aircraft shown in Fig. 4. Indeed aerodynamic modelling shows that this relationship can be described by the differential equation: Q(s)/d(s)=(7.25s+11.27)/(s^2+3.1s-8.82)
其中，gain 是指 gears，数值是-5

Sketch of pitch rate response to a step change in the control input here 输出的response图显示从0开始微乎其微的下降，直到16s开始大幅下降 Comment on the response The response of the pitch rate to a step change in the control input shows an initial small decrease from zero, followed by a significant decrease starting at 16 seconds. This suggests that the effect of the front fins on the pitch rate is not immediate, and takes some time to take effect. Additionally, the system seems to have some inherent delay or lag, as evidenced by the initial small decrease in pitch rate before the significant decrease. Overall, the response suggests that the front fins have a significant impact on controlling the pitch rate of the aircraft.