T-MOTOR MF2211 Polymer Folding Propeller

The T-MOTOR MF2211 is a folding two-blade propeller made of polymer with carbon fibre for heavy multicopters from T-MOTOR (China). It measures 22.4 in in diameter with an 8 in pitch; 568 is given as the figure in millimetres for the diameter. The blades fold for transport and are opened by centrifugal force in operation.

The 8 in pitch is a little over a third of the diameter: flat, laid out for hovering under load and efficiency at low rotational speed. T-MOTOR states the weight per single blade, 71 g; to compare it with complete propellers it is multiplied by the number of blades and the hub added. The maximum thrust is 11 kg. The speed of 6,500 rpm is the recommended maximum speed at those 11 kg and not an absolute limit. As a working range the manufacturer recommends 4 to 7 kg of thrust at 3,700 to 4,700 rpm, clearly below the maximum values.

Legally the aircraft counts: heavy multicopters with 22 in propellers operate at the edge of the open category, which ends at 25 kg take-off mass including payload. Above that the specific category applies, with a risk assessment of the operation. Aircraft of classes C1 to C3 additionally need direct remote ID and a geo-awareness function that warns of restricted zones.

On a folding propeller the hinge and blade seat are the wear points: they must be clean and free of play, and both blades must open evenly, otherwise imbalance results. Polymer with carbon fibre tolerates ground contact more forgivingly than pure carbon but picks up nicks at the tip and leading edge. Propellers are replaced in pairs; direction of rotation and motor shaft must match.