Integration of Aerodynamic, Performance, Stability and Control Requirements into the Design Process of Modern Unstable Fighter Aircraft Configurations,

Abstract : Already in the early design stage of a modern fighter aircraft development with usually unstable basic characteristics in pitch, a well balanced compromise between optimum performance and excellent handling qualities has to be found. This compromise must be based on sufficient margins for stability and control, maneuverability in terms of agility and economic aspects which usually are in contradiction to pure performance requirements as for example sustained/instantaneous turn rates and high specific excess power. In this paper reasonable criteria deducted from flight mechanical and control law design point of view are discussed, which lead straight ahead towards a set of desirable longitudinal and lateral characteristics for the basic unaugmented aircraft. These requirements impose remarkable constraints for the aerodynamic design of a fighter and its elements like wing planform, strakes, vertical fins and horizontal tail size and location. The problems and possibilities to stay within the reasonable flight mechanical limits are demonstrated.