This prop is used on the Explorer hovercraft.
Quick Ground Adjustable Magnum Airboat Paddle Propeller - how it works.
The IVOPROP operates with a unique adjustable pitch system that allows for substantially less hardware and rotating mass than any other ground pitch adjustable prop. The unique pitch adjustment design operates on the principle of twisting the blades through the chrome-moly alloy steel torsional rod cast inside the blade. The outer end of the torsional rod is firmly anchored inside the outer blade section. The round torsional rod is capable of rotating inside the blade, except for the outer end.
Adjust the pitch on the ground in a matter of seconds by turning the screw adjuster in the center of the prop. The super cams are installed on the end of the torsional rod. Each super cam fits into the groove in the screw adjuster. Turning the screw adjuster causes each cam to rotate and turn the torsional rod twisting the blade changing the prop pitch.