Which control changes the angle of incidence on all blades simultaneously?

• A. Throttle
• B. Collective
• C. Cyclic
• D. Pedals

Answer: (B)

The key idea is how rotor control inputs change the blade pitch, i.e., the angle of incidence, across the rotor disk. The collective control changes the pitch of all blades simultaneously. When you raise the collective, every blade increases its pitch by the same amount, increasing the angle of attack (relative wind vs. blade chord) for all blades and thus increasing overall rotor lift and thrust. Lowering the collective does the opposite.

In contrast, cyclic control varies the blade pitch as each blade passes through different azimuth positions, creating a pattern of lift around the disk that tilts the rotor thrust and tilts the helicopter. This is a staggered, time-varying change rather than a uniform change for all blades at once.

Throttle affects engine power and rotor speed, which influences thrust indirectly but does not set the blade angle of incidence. Pedals adjust yaw by changing tail-rotor thrust, not the blade pitch on the main rotor.