He was introduced to the sensitivity of stalling characteristics of wings to the boundary layer state near the suction peak by a change in paint scheme! The XBT-1 a forerunner to the famous SBD Dauntless alrcraft had good stall characteristics. The XBT-2 had exactly the same wing but had an unacceptable stall. The XBT-1 wing was completely painted with aluminum colored paint whereas the XBT-2 wing was painted yellow on the top and aluminum on the bottom. Where the colors joined at the leading edge, a slight ridge was formed by the masking tape during painting. John Wheatly, AMOs’ boss, took out his pocket knife and scraped away the ridge. When the XBT-2 was stalled again, the vicious stall had completely disappeared. This interaction of the boundary layer with stall characteristics obviously made an impression on AMO.
On AMO Smith, Life of a Gentle Genius