Fly Faster and Use Less Gas Aircraft Development has developed a vortelator propeller kit that is capable of increasing your aircraft speed by 2 to 4 mph and your RPM by 20 to 50 RPM. Thatís if you have a fixed pitch propeller. If you have a constant speed propeller, for a given RPM and manifold pressure the propeller will be at a slightly larger pitch giving you more speed. This is accomplished by placing vortelators at certain critical locations on the propellerís most inefficient highest air drag areas. The vortelators will cause the boundary layer to stay attached to the propeller surface for a greater distance, and to keep the boundary layer thinner. The net result of these two actions is that it reduces both the profile drag and skin friction drag components of the parasite drag. Another way to think of it is that the wake behind the aircraft propeller will be smaller, thus requiring less horsepower to turn the propeller through the air for a given RPM. Behind the vortelator mini vortices are created as can be seen by the lines of oil that form behind the vortelator. These mini vortices sweep the oil to a point in between the mini vortices, and thatís how the oil lines are formed. Whenever one sees these characteristic oil lines forming behind the vortelator one knows the vortelator is working. The vortelator allows the air flow to stay attached to the lift strut for approximately 80% of the lift strutís chord. In the area where there is no vortelator, the air flow separates from the lift strut and becomes turbulent, at approximately 40% of the lift strutís chord, as can be seen from the pile up of oil at the 40% chord position. At the 40% chord position the lift strut is 2.01Ē thick, and at the 80% chord position the lift strut is 1.18Ē thick. That means the turbulent wake coming off the lift strut is only 59% as thick with the vortelator attached as without the vortelator attached. That also means with a narrower wake less horsepower is required to propel the lift strut through the air. 259-200 Propeller Vortelator Kit for Homebuilt Aircraft The propeller vortelator kit will increase the RPMís by 20 to 50, increase airspeed by 2 to 4 MPH and also works on constant speed propellers. It is compatible with and will restore prop guardís efficiency loss.