Propellers: fixed and constant speed
Why propeller blades are twisted, how a governor holds rpm constant, and what limits propeller efficiency.
11 min read · The airplane: engine and systems
After this lesson you can
- Explain why a propeller blade must be twisted from hub to tip.
- Describe the difference between a climb propeller and a cruise propeller, and read power from a tachometer on a fixed-pitch installation.
- Explain how a constant-speed propeller governor holds rpm steady, and how the throttle and propeller control divide the work of setting power.
- State why excessive manifold pressure at low rpm stresses the engine.
A propeller is a rotating wing: each section of blade has an airfoil shape, a chord, and an angle of attack, and produces a force perpendicular to its motion -- thrust, the propeller's equivalent of lift. Everything already learned about wings applies here, with one extra complication: unlike a fixed wing, different parts of a propeller blade travel at very different speeds at the same instant.
The rest of this lesson
- 1.Why the blade is twisted
- 2.Fixed-pitch propellers
- 3.Constant-speed propellers
- 4.Reading manifold pressure
- 5.Damage, ground handling, and limitations
These 5 sections, their figures, the checks along the way and the end-of-lesson quiz come with the PPL track. Paid once, yours for good.
Key terms
Try to recall each definition before turning the card.