I am working on the design of an aircraft (2 m long, wingspan = 3 m). The platform is longitudinally stable but it is very sensitive to the variation in CG location. For example, 1) CG_location = 100 mm from wing L.E, the static margin is about 15% of MAC. 2) CG_location = 105 mm from wing L.E, the static margin is about 8% of MAC. 3) CG_location = 110 mm from wing L.E, the static margin is about -1% of MAC. (Unstable: Cm vs Alpha curve slope becomes positive)
So, effectively while manufacturing the aircraft or while dropping the payload the CG of my aircraft should not vary more than 1 cm, otherwise it would become completely unstable. Taking into any manufacturing errors, the platform CG might not be exactly as expected and hence having such a small margin creates issues.
How should I deal with this issue? Can I have any suggestions on how do decrease the sensitivity of the longitudinal stability to the CG location? Thanks in advance.