SCCA Corvettes used to use fans from the tops of Corvair air-cooled engines on their wheels. My first car was a Corvair so I would point this out with pride to my friends when we went to races at Laguna Seca. They would then tell me that the fan was the only race-worthy part from my Corvair. The fans on the 65-69 'vairs are made of magnesium.
From the Greenwood Corvette website,
“On the front wheels, Greenwood ran a very early version of the air extractor fans -- he used cut-down Corvair fans bolted onto the wheel to help move air across the brake area.”