The forerunner of the Douglas Dolphin amphibious twin first flew in July 1930, nine months after the stock market crash became a historical marker for the impending Great Depression.
Airplane manufacturers of all types were not immune from the ravages of the Depression. Some companies succumbed, while others survived with a variety of offerings.
When Douglas improved on its Sinbad twin engine seaplane air yacht, leading to the amphibious and alliterative Douglas Dolphin of 1931, the company created a niche machine that would serve airlines, business leaders and, ultimately, the military.
The Dolphin had a traditional tailwheel stance, common for amphibians of the day, although one Dolphin was experimentally tested with tricycle landing gear that may have helped convince Douglas to embrace nosewheels for the DC-4 and XB-19.
The aluminum fuselage of the Dolphin received good marks for its water handling abilities. Historian Joseph Juptner described the shape of the Dolphin’s hull as free bottom, an engineering breakthrough that reduced water suction for quicker takeoffs for seaplanes employing this design.
The Dolphin’s cantilever wing was designed for wooden construction. Laminated spruce box wing spars hosted spruce and plywood wing rib trusses, all of which was covered with sheets of spruce plywood.
The Dolphin was 44 feet, 4 inches in length. Its wing spanned 60 feet. Engines used in the Dolphin could be Wrights or Pratt and Whitney variants in the 300 to 550 horsepower range.
The mounts for the two radial motors were struts above the wing, placing the engines and propellers out of the way of the water. Part of the structure giving strength to the overhead engine mount was a much smaller airfoil section spanning 20 feet, which also contributed some lift to the Dolphin.
The first Dolphin Model 1 tested its wings in September 1930. With speed ring cowlings, the Dolphin could max out at 141 miles per hour, cruise at 115, and land at 62. The gangly landing gear lifted up and outward to clear the water, but it remained in the slipstream as a drag penalty.
If customers weren’t fighting to be first in line for a luxurious amphibian like the Dolphin in the Depression, there were eventually enough sales to tally 58 aircraft built.
Wilmington-Catalina Airlines bought the first two Dolphins to shuttle between the offshore resort island and the mainland of California.
The Army picked up a few as C-21, C-26, and C-29 transports. When modified for observation missions, they became OA-3s and OA-4s.
The Treasury Department borrowed some Army Dolphins to fly border patrols during Prohibition. The seagoing capability of the Dolphin made it a natural for use by the Coast Guard and Navy.
Philip Wrigley, son of the chewing gum empire magnate, bought a Dolphin. William Vanderbilt bought two to shuttle to the Vanderbilt yacht.
But perhaps the most surprising purchaser of a Douglas Dolphin in 1934 was William E. Boeing, whose namesake company was a worthy rival of Douglas.
Occasionally, northwest flying pioneer Clayton Scott, who also worked for the Boeing company as a production test pilot, flew Mr. Boeing in his amphibious Dolphin.
Boeing’s Douglas Dolphin outlived the rest of the production run. Its subsequent life included service in Alaska. And today, this sole surviving Dolphin is a pampered display in Coast Guard livery in the National Naval Aviation Museum in Pensacola, Florida.
In August of 1934 two Douglas Dolphins, NC14239 and NC14240, were delivered to China National Aviation Corporation, C.N.A.C which was a subsidiary of Pan Am. They plied the China coast primarily between Shanghai and Swatow and eventually got rights to serve Hong Kong in 1936 when BOAC finally had sea planes that could serve the entire British Empire, and they allowed Pan Am Clippers reciprocal rights. There are a number of pictures of these airplanes in the China trade that can be found directly by Googleing: douglas dolphin c.n.a.c. But there are also 4 photos of NC14240 in the Min River off of Foochow China. They cannot be found by Google because they are in a Chinese Students school portfolio and aren’t labled as Douglas Dolphin. Doubt the photographer even knew what they were. They are photos 23-26 in Huang Wei Shih’s Photography final examination portfolio: Seaplane on the Min River, starting at: https://findit.library.yale.edu/catalog/digcoll:4205455 How I found them is another story.