When engine power increases, what happens to blade angle and angle of attack?

When engine power increases, what happens to blade angle and angle of attack?

• A. blade angle decreases and angle of attack increases
• B. blade angle increases and angle of attack remains low
• C. blade angle remains unchanged
• D. angle of attack decreases

Answer: (B)

As engine power rises, the propeller needs to bite more air to convert that power into thrust. That means the blade pitch (blade angle) is increased. At higher rotational speeds, the air moves faster past the blade, which would tend to push the angle of attack toward a safer, lower range if you didn’t adjust the pitch. By increasing the blade angle, you keep the angle of attack within an efficient, low range to avoid stalling while still extracting the extra power. So the blade angle goes up, and the angle of attack stays low.

As engine power rises, the propeller needs to bite more air to convert that power into thrust. That means the blade pitch (blade angle) is increased. At higher rotational speeds, the air moves faster past the blade, which would tend to push the angle of attack toward a safer, lower range if you didn’t adjust the pitch. By increasing the blade angle, you keep the angle of attack within an efficient, low range to avoid stalling while still extracting the extra power. So the blade angle goes up, and the angle of attack stays low.