The FCS of the EAP compensated for the effects of dynamic pressure by normalizing the control surface effectiveness within the control laws.[^1] This was accomplished with nonlinear control demand functions upstream of the actuation system commands.[^1] This simplified the gain scheduling by providing a linear pitching moment command point within the control law independent of the aircraft’s operating points.[^1] A complementary filter was combined with the mixed-airstream data to derive the incidence for pitch stiffness augmentation.[^1] This prevented unexpected transients when passing through the wake of another aircraft, where using only air data would give erroneous results.[^1] An automatic wings-leveling function reduced pilot workload when the wings were close to level.[^1] It also added a static-stability function where the pilot stick offset was scheduled by airspeed.[^1] This meant that the pilot would have to move the stick more aft as the speed got slower, This mimicked the speed stability characteristic cue of a conventional aircraft.[^1] The basic pitch mode was a pitch-rate demand with the dynamics that are tuned to a conventional AOA response for the short-period.[^1] Increasing stick demand was blended progressively into a normal acceleration demand, and then an AOA demand above the corner point.[^1] The flight control modes have seamless transitions with no difference between Wheels-up and Wheels-Down handling.[^1] A tracking filter in the pitch command provides attitude control to the frequency for fine tracking.[^1] The filter was modulated as a function of the amplitude and frequency of the control stick input.[^1] Direct paths to the control surfaces ensure fast responses.[^1] Maximum stick inputs at PIO frequencies completely prevented Type 2 and Type 3 PIO.[^1] a DPIA controller was used in a SISO structure.[^2]
[[Type 1 Higher-order Locked-In PIO]] – prevented by phase delays and attenuation without the 180 degree phase penalty.
Sources
- RTO-TR-029
- “Realization of the Eurofighter 2000 Primary Lateral/Directional Flight Control Laws with Differential PI-Algorithm.” Accessed: Feb. 10, 2024. [Online]. Available: https://arc.aiaa.org/doi/epdf/10.2514/6.2004-4751
Backlinks
Air-Data Sensors
[[Complementary Filter]]
[[DPIA Controller]]
[[Dynamic Pressure]]
[[Eurofighter Flight Control System]]
[[Experimental Aircraft Program (EAP)]]
[[Gain Scheduling]]
[[Inertial Measurement Unit]]
[[Linearizing Systems of Differential Equations]]
[[SISO Closed-Loop System]]
Speed Stability