Sure it is correct.
Most fighters are directionally unstable above 15-20 deg AOA even without roll input. Fortunately lateral stability helps.
During aileron rolls, 4.th gen. fighter’s ARI adds rudder automatically for rolling…
“At speeds and alphas close to stall, typical supersonic fighter response to aileron input is opposite – left stick produces roll to the right. Down going, right aileron generates more drag than left aileron and aircraft sideslips to the right – “adverse yaws”. Roll moment of the sideslip (lateral stability)overpowers aileron’s roll moment. In that case rudder is more effective for roll control. At some higher α rudder effectiveness diminishes and lateral controls can be used for directional control. That means if one wants to roll, up to 10-20º α it would use ailerons, after that rudders are safer and more effective (either one can force the aircraft to the spin) and at higher α, where rudder lose effectiveness, opposite aileron can be only yaw and thus roll control.” ….source:
http://cgi.ebay.com/Fighter-Performance-in-Practice-F-4-Phantom-vs-MIG-21_W0QQitemZ290490431752QQcategoryZ2228QQcmdZViewItemQQ_trksidZp4340.m444QQ_trkparmsZalgo%3DCRX%26its%3DC%252BS%26itu%3DSI%252BUA%252BLM%252BLA%26otn%3D5%26ps%3D63%26clkid%3D4815990259887496461
Aircraft can be designed laterally unstable for max roll rate and acceleration, but dynamic directional stability would suffer, besides constant need for lateral trimming.
Upper graph depicts response to roll command for pure lateral controls and for one refined with Command Augmentation System / ARI.
Lower diagram shows roll rate vs static longitudinal stability (usual +2% to -10%). Roll rate decay with increased longitudinal instability is because of need to arrest more pronounced inertial coupling.
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