Where is lift greatest on a typical rotor blade under the discussed conditions?

• A. At the tip
• B. At the root
• C. Mid-span
• D. Quarter-span

Answer: (A)

Lift on a rotor blade element scales with the dynamic pressure 0.5 ρ V_rel^2, the local chord, and the lift coefficient. For a rotor, the relative wind speed V_rel is dominated by the blade’s rotation and increases with radius (V_rel ≈ ΩR). So elements near the tip experience the highest V_rel, and with similar chord and airfoil performance, they generate more lift per unit span than elements closer to the hub. The root sees much less relative wind speed, so its lift contribution per span is smaller, while mid-span and quarter-span are intermediate. Even with twist and taper designed to balance loading, the outer sections still produce the greatest lift due to the much higher local speed, making the tip region the place where lift is greatest.