The Kinner K-5 was a popular engine for light general and sport aircraft developed by Winfield B. 'Bert' Kinner.[1] With the boom in civilian aviation after Charles Lindbergh's transatlantic flight the K-5 sold well. The K-5 was a rough running[citation needed] but reliable engine and the K-5 and its derivatives were produced in the thousands, powering many World War II trainer aircraft.