What effect does tilting the nose of a helicopter downward have during straight and level flight with constant power?

Tilting the nose of a helicopter downward during straight and level flight with constant power affects the helicopter's aerodynamics and flight dynamics. When the nose is tilted down, the helicopter begins to enter a descent because the change in angle of attack decreases lift. In level flight, lift must equal weight to maintain altitude. By lowering the nose, the rotor blades produce less lift, resulting in a scenario where the weight of the helicopter exceeds the available lift, causing it to descend initially.

In this situation, even though the rotor system is still operating at a constant power setting, the reduction in lift due to the altered angle of attack cannot sustain the altitude, leading to a decrease in altitude. Understanding this principle is essential for pilots, as it impacts how they manage flight phases and control the helicopter effectively.