Thesis - Leigh Moody.pdf - Bad Request - Cranfield University

Chapter 9 / Performance
_ _
TIME TO IMPACT ( seconds )
MISS DISTANCE ( metres )
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
2 2.5 3 3.5 4
KINEMATIC GAIN
4.5 5 5.5 6
39.2
39.15
39.1
39.05
39
38.95
38.9
38.85
Figure 9-7 : Miss Distance vs PN Gain
38.8
2 2.5 3 3.5 4
KINEMATIC GAIN
4.5 5 5.5 6
Figure 9-8 : Flight time vs PN Gain
Cases PN01 (blue), PN02 (green) and PN07 (red) are compared in Figure
9-9 to Figure 9-12. The traces terminate just before impact with respect to
the shortest flight time. PN02 (no compensation) shows the typical LOS
rate increase and lateral acceleration limiting when the missile is close to
impact with a commensurate drop in impact speed. Performance is much
the same until the target manoeuvres and target acceleration compensation
improves the terminal flight profile maintaining the impact speed.
The performance in cases PN03 (gain := 2 - green), PN07 (gain := 4 - blue)
and PN09 (gain := 6 - red) are compared in Figure 9-13 to Figure 9-16.
With the target is flying at constant velocity, reducing the rate at which the a
collision course is established by dropping the gain to 2 reduces incidence
and hence improves missile speed. However, if the target manoeuvres
guidance is clearly inadequate and control saturation ensues. Increasing the
gain to 6 rapidly establishes the impact geometry at the expense of speed
and higher incidence eventually resulting in a reduced impact speed of
9-10