HQProp Ltd Juicy Prop J35 (4.9x3.5x3)

The HQProp Juicy Prop J35 (4.9x3.5x3) is a three-blade polycarbonate propeller for freestyle flying with FPV quadcopters of the 5 in class. The designation gives diameter, pitch and blade count: 4.9 in, 3.5 in, three blades. At 4.9 in diameter it sits slightly below the usual 5 in size.

The 3.5 in pitch is a good two thirds of the diameter: a middle value that balances static thrust and speed and runs at moderate current draw. Three blades give thrust and grip at just under 5 in and cost efficiency. The weight is 3.6 g and the bore 5 mm; the hub measures 12 mm across and 6 mm in thickness. The propeller does not fold.

Freestyle belongs in the open category. There, visual contact with the aircraft, a maximum altitude of 120 m and, with video goggles, an observer apply. Take-off mass including battery and camera decides the classification; from 250 g operator registration is mandatory. The distance from uninvolved people depends on the class, 30 m for C2, and the aircraft must not fly over crowds.

On selection: the 5 mm bore fits 5 mm motor shafts. Polycarbonate takes ground contact forgivingly, but after every impact the blade tips, leading edges and hub should be checked; even a fine nick changes the thrust of a single blade and with it the vibration pattern. Changes are made by the set with two propellers per direction of rotation, and propellers of different types are not mixed on one frame.