Douglas DC-6 R6D-1

The R6D-1 is the United States Navy's DC-6A, of which 65 were built. It differs from its Air Force equivalent, the C-118A, in its powerplant: it carries the more powerful R-2800-CB-17 engines, later used on the commercial DC-6B to make international flights possible. In the late 1950s and early 1960s the R6D flew with Curtiss Electric constant-speed reversing propellers.

Four R6D-1s were converted as staff transports under the designation R6D-1Z. When the United States unified its military designations, the R6D-1 became the C-118B and the R6D-1Z the VC-118B.