Propellerblatts

Propeller blades are the rotating foils of a propeller that generate thrust by accelerating fluid rearward. Mounted on a hub, they convert rotational motion into a net force along the propulsion axis. Propeller blades are used in aircraft propulsion (propeller-driven aircraft and unmanned aerial systems) and marine propulsion (ships, boats, and submarines), as well as in some hydrokinetic devices.

Each blade has an airfoil-shaped cross-section and is twisted along its span to maintain a favorable angle of attack from root to tip. The number of blades and their pitch determine the thrust and efficiency at a given speed; common configurations range from two to five blades, with fixed-pitch or controllable-pitch designs. Blades are designed to balance strength, stiffness, weight, and fatigue resistance, and may be metal, composite, or wood depending on application.

Materials and manufacturing methods vary: metal blades are often aluminium alloys or steel; composite blades use carbon fiber or glass fiber reinforced polymers. Manufacturing may involve forging or machining for metals, or composite lay-up, curing, and bonding. Surface treatments reduce wear, corrosion, and cavitation damage, while precise balancing prevents vibration during operation.

Performance is described by thrust, torque, and efficiency, which depend on geometry, material, speed, and fluid properties. At high speeds, issues such as cavitation in water or compressibility effects in air can limit performance and increase noise. Regular inspection for cracks, delamination, corrosion, and wear is part of maintenance, along with periodic balancing and blade replacement when necessary.