Nikolai Kudryavtsev was a Russian scientist who lived in the early 1900s. He is best known for his work on aerodynamics, which is the study of how air moves around objects. He developed a method called linear theory which was used to help mathematicians and physicists understand how air flowed around things like wings and propellers. His methods are still used today to make carriers, airplanes, and other aircraft fly more safely and efficiently.