APC Propellers (Landing Products Inc.) 10x4.7SFP Slow Flyer Pusher

The APC 10x4.7SFP is a Slow Flyer series propeller from APC Propellers (Landing Products Inc., USA) for mid-sized multicopters. The P at the end of the designation stands for Pusher, the reverse-rotation version of the series: it turns opposite to the standard Slow Flyer propeller and completes it as a rotation-direction pair. Slow Flyer propellers are used on small multicopters and on slow fixed-wing models.

The propeller measures 10 in in diameter with a 4.7 in pitch. Pitch, the theoretical distance advanced per revolution, sits at just under half the diameter, in the flat range typical of hovering and slow flight; high pitch brings speed. Two blades keep efficiency higher than a multi-blade propeller of the same diameter. At 11.9 g (APC lists 0.42 oz) the rotating mass is small, so the motor adjusts its speed quickly. The bore is 6.35 mm, a quarter inch. The maximum speed of 6,500 rpm follows the APC rule of 65,000 divided by the diameter in inches and is a rule-of-thumb figure for the series, not a test value.

The finished aircraft falls under the EU classes C0 to C6: C0 is under 250 g take-off mass, C1 under 900 g, C2 under 4 kg, and C3 and C4 under 25 kg. The propeller carries no class of its own but belongs to the propulsion system on which the manufacturer's classification rests. Direct remote ID is required for classes C1 to C3.

Direction of rotation comes first when choosing: as a pusher it turns opposite to the standard type and belongs on motors with the matching direction. The bore must fit the motor shaft or an adapter ring. It is injection moulded; after ground contact nicks on the leading edge, cracks at the hub and an enlarged bore are typical. A damaged propeller runs out of balance and the vibration disturbs the attitude sensors, so it should be replaced.