Ludwig Kort was a German
fluid dynamicist known for developing the
ducted propeller, or Kort nozzle. In an attempt to reduce canal
erosion, Kort discovered that directing the
wake of a propeller through a short, stationary
nozzle also increased
thrust. He submitted a
U.S. patent for this technique, which was awarded in 1936. His research showed that the performance of ducted propellers heavily depended on the cross-section and thickness of the duct.