, is the "gold standard" for understanding how aircraft stay in the air and respond to the pilot's touch.
Algebraic simplification of the $[\Phi(s)/\delta_a(s)]$ transfer function. The Nelson Solution: Automatic control solutions in Nelson’s style rely on the "Nelson approximation" for roll subsidence. The full solution simplifies the roll mode to a first-order lag: $$ \frac\phi(s)\delta_a(s) \approx \fracL_\delta_as(s + L_p) $$ Flight Stability And Automatic Control Nelson Solutions