Editing Flap (aeronautics) (section)

=== Split flap ===
The rear portion of the lower surface of the airfoil hinges downwards from the leading edge of the flap, while the upper surface stays immobile.<ref>Gunston 2004, p. 584.</ref> This can cause large changes in longitudinal trim, pitching the nose either down or up. At full deflection, a split flaps acts much like a spoiler, adding significantly to drag coefficient.{{Fact|date=February 2024|reason=See talk page for discussion}} It also adds a little to lift coefficient. It was invented by [[Orville Wright]] and James M. H. Jacobs in 1920, but only became common in the 1930s and was then quickly superseded.<ref>{{cite interview |last=Jacobs |first=James Wilbur |interviewer=Susan Bennet |title=Interview with James Wilbur Jacobs |url=http://ecommons.udayton.edu/cgi/viewcontent.cgi?article=1010&context=archives_wrightkett_oh |publisher=University of Dayton |date=4 March 1967 |work=eCommons |access-date=20 July 2020 |archive-date=18 March 2020 |archive-url=https://web.archive.org/web/20200318185137/https://ecommons.udayton.edu/cgi/viewcontent.cgi?article=1010&context=archives_wrightkett_oh |url-status=live }}</ref>{{Failed verification|date=July 2020}} The [[Douglas DC-1]] (progenitor to the DC-3 and C-47) was one of the first of many aircraft types to use split flaps.