Coast Guard Dolphin in NYC
Aero Digest specs
East Boston (now Logan) airport in 1936.
Eight-place high-wing amphibion monoplane.
Two P. & W. Wasp engines, 450 h.p. each.
The Douglas Dolphin was an amphibious flying boat. While fewer than 60 were built, they served a wide variety of roles: private ” air yacht”, airliner, military transport, and search and rescue. It began in 1930 as the twin-engine “Sinbad,” intended as a luxury aircraft. It was a high-wing monoplane, with two radial engines mounted above the wing. Its six to eight passengers looked out picture windows, and their baggage was stored in a 30-cubic-foot area. The Depression curtailed demand for such extravagance, so the Sinbad was sold to the United States Coast Guard.
58 of the next version, the Dolphin, were built between 1931 and 1934. The Dolphin retracted its landing gear for water landings and evolved into 17 variants to meet military or civilian needs. It . Among the first purchasers were the Wilmington – Catalina Airline and Standard Oil of New Jersey.
The U.S. Army, Navy and Coast Guard bought the Dolphin in quantities; the Coast Guard version known as the RD (RD-1, RD-2, and RD-4). The detailed picture showing the two large high-mounted engines is an RD-4, taken in New York City. More on Coast Guard Dolphins at the Coast Guard history site.
From Aero Digest, April, 1935:
Douglas Aircraft Corporation, Santa Monica, California
• President : Donald W. Douglas. Vice president and General Manager: H. H. Wetzel. Vice-president in charge of Sales: C. C. Cover. Vice-president in charge of Engineer¬ing:. A. E. Raymond. Export representatives: N. V. Nederlandsche Vliegtuigenfabriek, Fokker, Rokin 84, Amsterdam, Holland. E. P. Howard, 51 Canton Road, Shanghai, China.
Span 60 feet. Length overall 45 feet 2% inches. Height overall 17 feet 1 inch. Wing area 592 square feet. Power loading 10.6 pounds per horsepower. Wing loading 16 pounds per square foot.
Empty weight 6730 pounds. Useful load 2770 pounds. Payload 938 pounds. Gross weight 9500 pounds. Fuel capacity 252 gallons. Oil capacity 20 gallons.
Maximum speed 156 miles per hour. Cruising speed 140 miles per hour at 10,500 feet. Landing speed 64 miles per hour. Service ceiling 19,800 feet. Rate of climb
710 feet per minute. Cruising range 720 miles.
Hull: riveted aluminum alloy with 6 watertight compartments. Wing: full cantilever, box spars of spruce and plywood covering; hydraulically operated flaps in”" trailing edge of wing outboard of hull on either side; spars, ribs, webs and covering of three-ply mahogany; stringers, battens, blocks and gussets of spruce; trailing edge reinforced with copper strip. Tail group: all-metal stabilizer and fin; rudder and elevators metal frame, fabric covered; trailing edge flaps for balancing trim on elevators. Landing gear: retractable, equipped with 36 X 8 Goodyear tires, Bendix wheels and brakes, and hydraulic shock absorbers. Full swiveling tail wheel. Self lubricating ball bearings for engine and plane controls.
Standard equipment includes Hamilton Standard metal propeller, Exide battery. Optional equipment includes radio, landing lights, and controllable-pitch propeller. Also see data in March, 1931, AERO DIGEST.