Longitudinal Stability Criteria for a Propeller-Driven Aircraft

Figure 1

Stability boundaries for the model aircraft. Combinations of lift coefficient and stability margin are unstable if situated to the right (b) or above (a, c, d) the respective line. Thick lines mark the exact boundaries obtained from multiple solutions of (4); thin lines are solutions of𝐽(𝑋)=𝑖_𝑦.

(a) level flight, 𝑘_T=2

(b) 8 deg climb, 𝑘_T=2

(c) level flight, 𝑘_T=3

(d) power off glide