Multipurpose Flying Boat
Douglas Dolphin. The Dolphin amphibious flying boat was a cantilever monoplane with a high wing, first flown in July 1930.
The boat had an all-metal hull and a wooden wing with plywood sheathing. In flight, or when operating from the water, the main landing gear was retracted above the waterline. The pilots sat side by side in a fully enclosed cockpit in front of the wing. The passenger compartment began behind them. The Dolphin had a distinctive auxiliary aerodynamic surface over the tops of the engine nacelles to eliminate flow problems. Early examples had a pair of auxiliary keels to provide additional longitudinal stability.
The first two boats were purchased by Wilmington-Catalina Airlines to carry passengers between Los Angeles and Santa Catalina Island, becoming the first successful Douglas airliners. Subsequent examples were ordered by the US Navy and the US Coast Guard for use as transport and search and rescue vehicles. The US Army Air Corps ordered several boats under the designations C-21, C-26 and C-29. Many were eventually used for their original purpose as luxury vehicles. The flying boats were owned by William Boeing, founder of Boeing, and Philip K. Wrigley, son of the founder of Wm. Wrigley Jr. Company. William K. Vanderbilt bought two boats with custom interiors for use on the Vanderbilt Alva.
One Dolphin was acquired by the US Navy to transport President Franklin D. Roosevelt. Although it was never used by Roosevelt, it was the first aircraft designed to carry the President of the United States.
In 1933, after landing on the high seas, the USCG RD-4 carried out several rescue operations at sea to rescue civilian sailors from a merchant ship, which resulted in impressive news reports and amazed the American public.
Serial production of Dolphin boats continued until 1935. Most of these vehicles ended up in the Army, Navy, and the US Coast Guard. Several of these boats survived World War II.
A total of 58 Dolphin boats were produced.