At full deflection, a split flaps acts much like a spoiler, adding significantly to drag coefficient. 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was invented by Orville Wright and James M. H. Jacobs in 1920, but only became common in the 1930s and was then quickly superseded.[11][failed verification] The Douglas DC-1 (progenitor to the DC-3 and C-47) was one of the first of many aircraft types to use split flaps.