DALPROP Cyclone 7040 Zweiblatt

The DALPROP Cyclone 7040 is a two-blade polycarbonate propeller for small-class FPV drones. The designation 7040 encodes 7 in diameter and 4 in pitch. It is intended for long-range builds, that is, aircraft meant to cover long distances at low to medium rotational speed rather than being tuned for maximum acceleration.

With a 4 in pitch on a 7 in diameter the propeller is flat; that keeps the current draw per unit of thrust low and favours flight time over top speed. At this diameter two blades give better efficiency than three but less thrust at the same speed. The weight is 5.7 g, the bore 5 mm and the hub height 7 mm. Thrust can only ever be quoted for a given motor, voltage and speed, not for the propeller alone.

For the legal framework the finished aircraft counts. Whether a build with 7 in propellers lies below or above 250 g take-off mass depends on its equipment: below 250 g class C0 applies, above it operator registration is mandatory, and for classes C1 (under 900 g) to C3 direct remote ID is added. The propeller carries no class, but with its weight and thrust it helps decide which weight class a build can fall into.

When buying, check the shaft: the 5 mm bore must fit the motor shaft, and the 7 mm hub height must suit the free shaft length under the nut. Polycarbonate is tough and tends to deform in a crash rather than splinter, but it picks up nicks and stress whitening at the blade root. Nicked or bent blades cause imbalance and vibration that disturb video quality and sensors; the whole set is then replaced.