Performance, mass & POF

Formulas appendix032 / 031 / 081

032 Performance

Formula —

Power = thrust × speed | Climb gradient = (rate of climb / TAS) × 6080 / 6000 (approx)

Formula —

Hydroplaning speed (kt) = 9 × √P (psi) — bar × 14.5 = psi

Key fact

TODA = TORA + clearway | ASDA = TORA + stopway | Balanced field: TODA = ASDA. Jets land in 60% LDA; props/class B in 70%.

Formula —

V2 at screen height OEI | VR greater than 1.05 VMCA | V4 = V2 + 10 kt (all engines)

031 Mass & balance

Formula —

Moment = mass × arm | CG = total moment / total mass

Formula —

% MAC = (CG − LEMAC) / MAC × 100 — MAC = TEMAC − LEMAC

Formula —

Load shift: d / D = m / M — d = CG change, D = distance between stations, m = mass moved, M = total mass

Formula —

Max traffic load = MTOM − DOM − fuel on board (lowest of MTOM, MZFM+TOF, MLM+trip limits)

Key fact

Vs proportional to √weight. Forward CG ≈ heavier aircraft effects; aft CG ≈ lighter.

081 Principles of flight

Formula —

Dynamic pressure Q = ½ρV² — lift and drag proportional to EAS²

Formula —

Lift = CL × ½ρV² × S | Drag = CD × ½ρV² × S

Formula —

Best range jet = 1.32 × VIMD | Best endurance prop ≈ VIMP

Formula —

Mach = TAS / LSS | LSS (kt) ≈ 38.94 × √T(K)

Key fact

Below VIMD = speed unstable regime (drag rises as speed falls). Induced drag ∝ 1/EAS²; profile drag roughly constant with EAS.