This image was acquired from
flickr. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
blackandwhite monochrome text black and white This horsepower propeller dynamometer was used in the Foot Pressure Wind Tunnel to test the performance and efficiency of propeller and spinner designs at speeds up to revolutions per minute. An optional gearbox not shown permitted dual counterrotating propellers to be tested. This horsepower