An open rotor, also known as a high-speed propeller, is tested in a wind tunnel. The propeller moves much more quickly than a standard propeller, and the blades of the propeller are shaped differently. In the counter rotating setting (which is being tested at Glenn) one high-speed propeller spins in one direction while another high-speed propeller directly behind it spins in the other direction. This increases fuel efficiency while reducing the amount of noise produced.
