T-MOTOR P21x6.3 Polished Carbon Fiber Propeller

The T-MOTOR P21x6.3 is a polished, one-piece two-blade propeller made of carbon fibre with epoxy resin for heavy multicopters from T-MOTOR (China). It measures 21 in in diameter with a 6.3 in pitch; 533.4 is given as the figure in millimetres for the diameter. The propeller does not fold.

The 6.3 in pitch is just under a third of the diameter: very flat, laid out for hovering under load and efficiency at low rotational speed. The weight is given as 58 g; T-MOTOR labels the figure as the weight of a single blade, so it is not suitable for comparison with complete propellers from other manufacturers. The thrust limit (Thrust Limitation) is 10.8 kg. As an optimal range the manufacturer gives 2,900 to 5,000 rpm. Thrust holds only with a given motor, voltage and speed and cannot be quoted for the propeller alone.

Legally the aircraft counts: heavy multicopters with 21 in propellers lie, depending on take-off mass, at or above the limit of the open category, which ends at 25 kg including payload. In class C3 subcategory A3 applies with 150 m distance from residential, commercial, industrial and recreational areas and direct remote ID. Beyond that the specific category begins, with a risk assessment of the operation. A 21 in blade demands distance from people and a de-energised drive before any work at the propeller.

On selection: the polished one-piece construction has no folding hinges that can wear; the load sits at the fixing on the motor shaft and at the edges. Frayed edges, nicks at the tip and dull-sounding areas point to delamination and are reasons to replace. Propellers are replaced in pairs, with the direction of rotation matching the motor, so that thrust and vibration pattern stay the same on all arms.