Retreating Blade Stall occurs when the pitch on the retreating blade cannot compensate for what?

Retreating Blade Stall occurs when the pitch on the retreating blade cannot compensate for what?

• A. the forward gusts
• B. the reverse flow area and stall region from the retreating blade tip
• C. the tail rotor wind
• D. engine power fluctuation

Answer: (B)

Retreating blade stall happens because, in forward flight, the blade moving opposite to the flight direction (the retreating blade) loses relative wind and faces a flow field that can develop a reverse flow and a stall-prone region near the tip. The rotor system can increase the retreating blade’s pitch to compensate, but there’s a practical limit; the reverse flow area and the stall region at the retreating blade tip can demand more lift than the blade can provide with feasible pitch increases. When the blade cannot overcome that low-energy, reversed/retreating-flow condition, it stalls. That’s why the best answer points to the reverse flow area and the stall region from the retreating blade tip.

Retreating blade stall happens because, in forward flight, the blade moving opposite to the flight direction (the retreating blade) loses relative wind and faces a flow field that can develop a reverse flow and a stall-prone region near the tip. The rotor system can increase the retreating blade’s pitch to compensate, but there’s a practical limit; the reverse flow area and the stall region at the retreating blade tip can demand more lift than the blade can provide with feasible pitch increases. When the blade cannot overcome that low-energy, reversed/retreating-flow condition, it stalls. That’s why the best answer points to the reverse flow area and the stall region from the retreating blade tip.