Clayton Folkerts was a self-taught designer who created a series of racing airplanes in the 1930s. He built the Speed King SK-3 "Jupiter - Pride of Lemont" for mechanic Rudy Kling of Lemont, Illinois in 1937. Kling won the 1937 Thompson Trophy Race in the SK-3, but was killed when it crashed at the 1938 Miami Air Races. Thompson Products, who sponsored the race, donated this model.