KDE Direct CF245-DP Dual-Edition Propeller Blades 24.5x8.1

The KDE-CF245-DP Dual-Edition propeller blades from KDE Direct (USA) are two-blade propeller blades made of 3K carbon fibre, 24.5 in in diameter and 8.1 in in pitch, for the heavy-lift adapters of KDE Direct on heavy multicopters. They are sold as matched sets for clockwise and counter-clockwise rotation (CW/CCW): the box holds two blades for clockwise and two for counter-clockwise rotation, that is, one pair of propellers. 3K denotes a weave with 3,000 filaments per fibre tow.

The weight is given per blade at 34.9 g; to compare it with a complete propeller it is multiplied by the number of blades, with hub and adapter added. The installed diameter with adapter is 622.3 mm according to the dimensional drawing, and the blade bore is 5.5 mm with a continuous sleeve. The 8.1 in pitch is one third of the diameter and is laid out for hovering under heavy load. The performance curve has a thrust coefficient Ct of 0.0699 and a power coefficient Cp of 0.02009, measured at 3,500 ft altitude. With air density, rotational speed and diameter they can be used to calculate thrust and power for other conditions.

In the KDE motor datasheets the highest measured thrust with this propeller is 13,445 g, measured on the KDE7215XF-135 motor at 58.8 V with two blades. That is the measured value of this one combination, not a limit of the propeller. Aircraft with propellers of this size usually sit at or above the 25 kg limit of the open category; above it the specific category applies, in which operation rests on a risk assessment.

On selection: the blades fit only the KDE heavy-lift adapter, and the blade bore with its sleeve is the most highly loaded spot. At 24.5 in delamination shows as frayed edges and dull-sounding areas, and cracks around the bore are a reason to replace. Because the blades are sold as matched pairs, they are replaced together and blades from different sets are not mixed.