Reducing Gear Windage Losses From High Speed Gears and Applying These Principles to Actual Running Hardware

Windage losses in gearboxes account for a large portion of the total power loss in high-speed drive trains. Very little actual data has been collected specifically quantifying these losses. Traditional techniques to measure the effects of baffles in high speed gearing applications have been done by trial and error on very complex systems. This trial and error technique is used throughout the gearing industry to solve problems without isolating each individual gear windage effect. These solutions are usually sub-optimum. They cause time-consuming delays and cost overruns in many programs. This paper describes two gear baffle test rigs that were built to quantify and minimize the gear windage losses in high-speed drive trains. The intent of the first gearbox baffle test rig was to isolate and measure the windage effects on a single high-speed bevel gear with various baffle configurations. The results of these tests were used to define a basic set of ground rules for designing baffles. This set of ground rules was then applied to another rig replicating the F-35 Liftfan gear box configuration. Immediate benefits were seen. Without this work Lockheed Martin’s X-35 STOVL aircraft would not have been able to operate.