Douglas C-47 Skytrain - Super DC-3 (R4D-8)

Super DC-3 (R4D-8)

In response to proposed changes to the airworthiness requirements that would limit the continuing use of the large numbers of DC-3s and surplus C-47s in commercial use in the United States, Douglas offered a late 1940s conversion of the DC-3, modified to improve takeoff and single-engined performance, to meet the new Civil Air Regulations, and with increased speed to compete with newer airliners. The new model, the DC-3S or "Super DC-3", was 39 in (0.99 m) longer, allowing thirty passengers to be carried. It also had larger tail surfaces and new outer wings with a greater sweep back at the trailing edge to accommodate a rearward shift in the center of gravity. More powerful engines, either 1,475 hp (1,100 kW) Wright R-1820 Cyclones or 2,000 hp (1,490 kW) Pratt & Whitney R-2000s incorporated into larger engine nacelles, were installed along with shorter, jet ejection-type exhaust stacks. Minor changes included wheel well doors and a partially retractable tail wheel along with flush rivets and low drag antennas, that all contributed to a top speed of 250 mph. With greater than 75% of the original DC-3/C-47 configuration changed, the modified design was virtually a new aircraft. The first DC-3S made its maiden flight on 23 June 1949.

Although the changes fully met the new FAR 4B airworthiness requirements, and significantly improved performance, there was little interest from commercial operators in the DC-3S, which was too-expensive for the smaller operators who were its main target, with only three being sold to Capital Airlines. The U.S. Navy, however, had 100 of its R4D aircraft modified to Super DC-3 standard as the R4D-8, these later being redesignated C-117D.