US Patent 11746796 Plenum fan with telescoping blades

A fan wheel includes a pair of opposing parallel plates that rotate about an axis, one of the plates moves toward and away from the other of the plates along the axis. The fan wheel also includes a plurality of telescoping fan blades having opposite ends respectively mounted to the plates such that the one of the plates moves away from the other of the plates as the telescoping fan blades extend and the one of the plates moves toward the other of the plates as the telescoping fan blades retract.