General Aviation Aircraft Design Snorri Gudmundsson Pdf May 2026

Trade: reduce cruise speed to 140 kt (72 m/s) to get realistic engine size: Recompute q = 0.5×1.225×72² ≈ 3,178 CL = 7,166 / (3,178 ×14) ≈ 0.161 CD = 0.025 + 0.0486×0.161² ≈ 0.025 + 0.00126 ≈ 0.02626 D = 3,178×14×0.02626 ≈ 1,169 N Power = 1,169×72 ≈ 84,200 W = 113 hp shaft → engine ~130–160 hp (accounting prop eff and climb reserve). This is a practical choice (e.g., Lycoming IO-320/IO-360 class).