Douglas RD Dolphin
The Douglas Aircraft Company designed and manufactured the amphibious Dolphin in 1934, shortly after the flying boat Sinbad of the same design. Shortly after, meant during the Great Depression which was the bad luck with timing Douglas had when trying to sell his air yacht for carrying as many as eight passengers. There were a few buyers but fortunately the military signed contracts to have most of the slightly over four dozen which were produced. The aircraft could retract the main gear by shortening the oleo struts, making it an amphibian though an ungainly one as the “retracted gear” projected into the airstream at a 45º angle. A clear identifying characteristic is the wing that span both of the engines which are mounted atop the main wing (1934 was a time before engines were routinely faired into wings). I cannot find a source which mentions how well this may have worked aerodynamically but it must have been welcomed as a servicing platform by maintenance crews.
This RD, the RD-4, was originally bought and flown by William Boeing — yes, the Boeing — and ultimately came into the possession of the National Naval Aviation Museum* where it is displayed today. The U.S. Coast Guard flew most of them and that is why it has been restored in USCG livery.
- The fact sheet from the National Naval Aviation Museum
- Details of the Dolphins history and manufacture can be found here
* Posts of the National Naval Aviation Museum, and other exhibits, can easily be seen by pasting the museum name into the search window and selecting ENTER