How does transverse flow effect negatively the rear portion of the rotor disk?

Transverse flow effect negatively affects the rear portion of the rotor disk by increasing the induced flow and decreasing the angle of attack. Transverse flow effect happens as the helicopter accelerates. The front portion of the rotor disk acts like it is in clean, undisturbed air, while the rear portion of the rotor disk now has a downward flow from the front portion. This downward flow effectively reduces the angle of attack on the rear of the rotor disk requiring a greater blade pitch angle to compensate. This increased blade pitch causes an increase in drag, requiring the pilot to compensate with more power.