Case M5 Stability Report

Preliminary FDM result: inertia, control derivatives, rate damping, and propulsion are placeholders; ADB v1.1 contains alpha-beta data only.

Database Metadata

• File: adb_v1_1_drag_correction_m5.csv
• Moment/reference/CG: (-0.050, 0.000, 0.150) m
• rho: 1.090 kg/m^3, q_ref: 340.625 Pa, S: 1.805 m^2, b: 3.950 m, c: 0.457 m

Trim

• success: True
• alpha: 2.0061 deg
• theta: 2.0061 deg
• elevator: -5.5737 deg
• throttle: 0.1665
• residual norm: 4.705e-14

Static Stability Derivatives

• Cm_alpha: -0.291354 /rad (stable longitudinal static sign)
• Cn_beta: +0.028665 /rad (stable directional static sign)
• Cl_beta: -0.011511 /rad (stable lateral static sign)
• CL_alpha: +4.932043 /rad
• CY_beta: -0.226353 /rad

Dynamic Modes

Mode	Eigenvalues	wn rad/s	zeta	time constant s	Classification
phugoid	-0.024601+0.474923j; -0.024601-0.474923j	0.4756	0.0517	40.6487	stable
short_period	-4.45504+5.15473j; -4.45504-5.15473j	6.8131	0.6539	0.2245	stable
dutch-roll-like lateral-directional	No clearly identifiable Dutch-roll-like lateral-directional oscillatory mode was found in this linearization.	n/a	n/a	n/a	not identified
roll	-30.2267+0j	30.2267	1.0000	0.0331	stable
spiral	-0.00364264+0j	0.0036	1.0000	274.5265	stable

Summary

• Static stability: longitudinal stable, directional stable, lateral stable.
• Dynamic stability among identified reduced-order modes: stable.
• Weakly damped modes: phugoid.
• No clearly identifiable Dutch-roll-like lateral-directional oscillatory mode was found in this linearization. Because the aircraft uses an inverse V-tail/ruddervator layout and the current lateral reduced eigenspectrum is entirely real, treat this as a model limitation and classification ambiguity to investigate before flight-test use.

Conclusion

Case M5 is the recommended near-term development baseline from this sweep. It preserves stable identified longitudinal behavior with more margin than M5p5 while staying near the transition region that should be refined in future CG studies.