SAWE Report - Cal Poly San Luis Obispo

-0.6
-0.4
UNSTABLE
NEUTRAL
-0.2
Lift Coefficient (C L )
-0.25 -0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 0.2 0.25
0
0.2
0.4
M = 0.2
M = 1.6
0.6
0.8
Moment Coefficient (C m )
Figure 10.7 - Pitch Break Characteristics
This figure shows that as the Vendetta rotates and has some angle of attack in the low speed
subsonic (M=0.2) regime, it will want to continue to rotate and break away. In the supercruise,
the aircraft behaves mush more linearly. The subsonic characteristics are of some concern, but
even simple feedback schemes in the DFCS could solve this problem. The supersonic
characteristics are actually more desirable because the maneuvering required is very light and the
control system will not be oscillating the control surfaces, which creates unnecessary drag, to
keep the aircraft flying straight.
A full state-space based model for the aircraft driven by a Taylor expansion and fit into equations
of motion was developed for flight simulator validation. These forms are too complex for simple
dynamic analysis, so the literal factor forms of the dynamics modes were used to determine
flying qualities and conformity with MIL-8785C.
The literal factors are nothing more than simplifications of the transfer function forms for
longitudinal and lateral modes of interest. These forms omit insensitive stability derivatives. The
literal factor forms for the modes of interest are provided in the Appendix. The conformity with
the military specifications for handling quality is shown in Table 10.IV.
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