Can a blade designed for clockwise rotation work on a counterclockwise rotor?

The short answer

Do not assume so. A blade has a leading edge, trailing edge, twist and intended direction of relative airflow. Reversing rotor rotation changes that relationship. Physical attachment to the hub does not prove aerodynamic or structural suitability for the opposite direction in a small-wind assembly.

Specify the rotation from a fixed view

Clockwise is ambiguous without a viewing direction. Put an observer arrow on the assembly sketch, identify the shaft axis and label the intended leading edge. A blade photographed from the opposite side can appear to have reversed rotation while representing the same rotor. Resolve that descriptive ambiguity before considering whether the blade itself must change; a supplier should be able to reference a controlled rotor drawing.

Check the section orientation as well as the holes

Even if a root pattern accepts the blade, its section camber and pitch distribution may face the wrong relative flow after a rotation reversal. Turning a blade over is not generally equivalent to manufacturing the required opposite-handed shape, because root geometry and spanwise twist also move. The aerodynamic assessment must use the resulting three-dimensional geometry. The hub, generator and protective design additionally need an independently approved rotation relationship.

Ask for a direction-specific compatibility statement

For an OEM proposal, request the blade part identity, direction arrow and applicable hub/rotor drawing, together with the designer assessment of the intended rotation. OpenFAST coordinate documentation demonstrates the importance of section axes and twist signs, rather than proving interchangeability. MARSTON electric yaw does not establish rotor handedness or permission to reverse a machine. Keep a proposed direction change pending until its aerodynamic, structural and drivetrain consequences have been addressed for the exact equipment. A direction-specific blade drawing should also identify which surface faces the incoming flow in the intended assembly. That check prevents a correctly labelled clockwise arrow from concealing a differently interpreted blade orientation.