In April 1981, Mc Donnell - Douglas leased a DC-10-10 (47802/ 101) to test a pair of winglets. They were used to reduce the aerodynamic effect of wakes which appear at the wingtips and were successfully tested on a KC-135 in the 1970s. Although the KC-135 is a kind of 707 derivate, the DC-10 became the first commercial aircraft to be fitted with winglets.
The first flight took place on ... . 61 further flights out of Long Beach and Edwards Air Force Base - with and without the winglets - revealed that the winglets can save up to 3% of fuel. The greatest effect took place when both, upper and lower winglets, were used. The last flight took place in October of 1981 returning the DC-10 (without winglets) to Continental Airlines.
Douglas and the NASA were very satsified with the test results, but as the high recertification costs would not justify the costs for refitting, no further DC-10s with winglets appeared. However, the knowledge won in this program were later used on the Mc Donnell - Douglas MD-11. Further aircraft with winglets or smaller wingtip fences appeared in the 1980s and 1990s like the Boeing 747-400, the Boeing 737-700/800, the Canadair CRJ or the new Airbus models.