Douglas Dolphin

Dolphin

U.S. Coast Guard RD-2 in June, 1932
Role	Flying boat
Manufacturer	Douglas Aircraft Company
First flight	July 1930 (Sinbad)
Introduction	1931
Primary users	United States Navy^[1] United States Coast Guard^[1]
Number built	58^[2]

The Douglas Dolphin was an amphibious flying boat. While only 58 were built, they served a wide variety of roles: private 'air yacht', airliner, military transport, and search and rescue.^[3]

Design and development

The Dolphin originated in 1930 as the "Sinbad," a pure flying boat without wheels. The Sinbad was intended as a luxurious flying yacht. Undaunted by the lack of demand, Douglas improved the Sinbad in 1931 so that it was amphibious, and could land on water or land. The improved aircraft was named "Dolphin", however this did not represent the end of development, as many detail improvements were made, including an increase in the length of over a foot and several changes were made to the empennage, engine nacelles and wings.^[4] The Great Depression had curtailed demand for such extravagance as a "flying yacht", but Douglas managed to interest the United States Coast Guard who not only bought the Sinbad, but 12 Dolphins.^[5]

Operational history

A U.S. Coast Guard RD-1.

Douglas OA-4A with tricycle landing gear at Langley

The first two were purchased by Wilmington-Catalina Airlines to fly passengers between Los Angeles and Santa Catalina Island, becoming the first successful Douglas airliners. Subsequent examples were ordered by the United States Navy and U.S. Coast Guard for use as transports and search and rescue craft. The U.S. Army Air Corps ordered several under the designations C-21, C-26, and C-29. Many were eventually ordered for their original purpose as luxury transports. Owners included William Boeing, the founder of the Boeing Company, and Philip K. Wrigley, the son of the founder of the Wm. Wrigley Jr. Company. William K. Vanderbilt bought two with custom interiors for use from the Vanderbilt yacht Alva as flying tenders.^[6]^[7]

One was procured by the U.S. Navy as a transport for President Franklin D. Roosevelt.^[8] Although never used by Roosevelt, this was the first aircraft procured to provide transportation for the President of the United States.^[9]

In 1933, landing in heavy seas, the USCG RD-4 undertook some rescues of merchant sailors at sea, feats that made spectacular news reports, enthralling the American public.^[10]

Variants

A Y1C-21

A RD-4 in World War II

Data from:McDonnell Douglas Aircraft since 1920 Vol.1^[1]

Douglas Sinbad: The original prototype built as a flying boat, intended to be a luxurious flying yacht, first flown in July 1930. No orders were received for the Sinbad which was eventually bought by the U.S. Coast Guard.
Dolphin Model 1: The initial two Dolphins built for the Wilmington-Catalina Airline Ltd. as six-seat airliners.
Dolphin Model 1 Special: The Model 1s redesignated after modification to seat eight passengers.
Dolphin Model 3: The third commercial Dolphin built as a luxury transport named Lesgo with seats for two crew and four passengers for Powell Crosley Jr., powered by 2x 300 hp (224 kW) Pratt & Whitney Wasp Junior A engines. Later impressed into the RAAF as A35-3.
Dolphin 113: One aircraft named Jade Blanc V for French clothing manufacturer Armand Esders (who also owned a Bugatti Royale) similar to the RD-4, powered by 2x 550 hp (410 kW) Pratt & Whitney R-1340-S1H1 Wasp engines.
Dolphin 114: A single Dolphin built to order for Philip K. Wrigley, powered by 2x 450 hp (336 kW) Pratt & Whitney Wasp SC1 engines.
Dolphin 116: One aircraft for the Armada Argentina (Argentine Navy), powered by 2x 450 hp (336 kW) P&W R-1340-96.
Dolphin 117: One aircraft initially named Rover, bought by William E. Boeing, which ended up in CAA (forerunner of the current Federal Aviation Administration) service. Sole surviving example, painted in USCG markings.
Dolphin 119: Two aircraft built for A.G. Vanderbilt II and W.K. Vanderbilt II and operated from the yacht Alva. One of the two (which is unknown) joined the RAAF as A35-2.
Dolphin 129: Two aircraft ordered by Pan American Airways for its subsidiary (at that time) China National Aviation Corporation, powered by 2x 450 hp (336 kW) Pratt & Whitney Wasp S3D1 engines. One crashed in heavy seas and the other was destroyed during or shortly after the Japanese invasion of China.
Dolphin 136: A single Dolphin, powered by 2x 450 hp (336 kW) Pratt & Whitney Wasp Junior SB engines, ordered by Standard Oil and later impressed by the RAAF as A35-1.
FP-1: Several C-21 aircraft loaned to the U.S. Treasury Department for border patrols during Prohibition.
FP-2: The two Y1C-26 Dolphins during a brief attachment to the U.S. Treasury Department.
FP-2A: The designation used by those Y1C-26A aircraft that were attached to the U.S. Treasury Department.
FP-2B: The two C-29s when in use by the U.S. Treasury Department.
RD-1: One aircraft, powered by 2x 435 hp (324 kW) Wright R-975E radial engines, operated by the U.S. Navy.
RD-2: Four Dolphin aircraft of two distinct types. One Aircraft similar to the Y1C-21 and powered by 2x 500 hp (373 kW) Pratt & Whitney R-1340-10 engines, for the U.S. Coast Guard. Two were U.S. Navy VIP staff transports similar to the Y1C-26 powered by 2x 450 hp (336 kW) Pratt & Whitney R-1340-96 engines. The final aircraft was completed for the U.S. Navy as the first presidential aircraft, for Franklin D. Roosevelt, powered initially by 2x 410 hp (306 kW) Pratt & Whitney R-1340-1 engines and later by 2x 500 hp (373 kW) Pratt & Whitney R-1340-10 engines, seating five though it was reportedly never used by the President.
RD-3: A utility transport version of the RD-2, six of which were built for the U.S. Navy, powered by 2x 500 hp (373 kW) Pratt & Whitney R-1340-4 or by 2x 500 hp (373 kW) Pratt & Whitney R-1340-96 engines.
RD-4: Ten aircraft for the U.S. Coast Guard, powered by 2x 420 hp (313 kW) Pratt & Whitney Wasp C1 engines.
OA-3: C-21 aircraft redesignated.
OA-4: C-26 aircraft redesignated.
OA-4A: Y1C-26A aircraft redesignated.
OA-4B: C-26B aircraft redesignated, one of which was fitted with an experimental fixed tricycle undercarriage.
OA-4C: Four OA-4A and one OA-4B aircraft modernized in 1936.
Y1C-21: Eight aircraft for the USAAS, similar to the Navy's RD-1, powered by 2x 350 hp (261 kW) Wright R-975-3 engines.
Y1C-26: Two aircraft for the USAAS with increased dimensions, fin area and fuel capacity (from180 US gal (681 l) to 240 US gal (908 l)). Powered by 2x 300 hp (224 kW) Pratt & Whitney R-985-1 engines.
Y1C-26A: Eight aircraft for the USAAS differing from the Y1C-26 only in minor details.
C-21: Y1C-21 aircraft redesignated.
C-26: Y1C-26 aircraft redesignated.
C-26A: Y1C-26A aircraft redesignated.
C-26B: Four aircraft powered by 2x 400 hp (298 kW) Pratt & Whitney R-985-9 engines.
C-29: Two Dolphins, powered by 2x 550 hp (410 kW) Pratt & Whitney R-1340-29 engines, were essentially similar to the Y1C-26As.

Military operators

The sole surviving Douglas Dolphin at the U.S. National Museum of Naval Aviation.

Argentina

Argentine Naval Aviation

Australia

Royal Australian Air Force

United States

Specifications (RD-3 Dolphin)

Data from McDonnell Douglas Aircraft since 1920, Vol. 1^[11]

General characteristics

Crew: Two, pilot and co-pilot
Capacity: Six passengers
Length: 45 ft 3 in (13.79 m)
Wingspan: 60 ft (18 m)
Height: 15 ft 2 in (4.62 m)
Wing area: 637 sq ft (59.2 m²)
Empty weight: 6,764 lb (3,068 kg)
Gross weight: 9,734 lb (4,415 kg)
Fuel capacity: 240 US gal (908 l)
Powerplant: 2 × Pratt & Whitney R-1340-4 Wasp 9-cyl. air-cooled radial piston engines, 450 hp (340 kW) each

or 2x 450 hp (336 kW) Pratt & Whitney R-1340-96 Wasp engines

Performance

Maximum speed: 149 mph (240 km/h; 129 kn) at sea level
Cruise speed: 105 mph (169 km/h; 91 kn)
Range: 692 mi (601 nmi; 1,114 km)
Service ceiling: 15,100 ft (4,600 m)
Rate of climb: 806.5 ft/min (4.097 m/s)
Time to altitude: 5,000 ft (1,524 m) in 6 minutes, 12 seconds
Wing loading: 16.4 lb/sq ft (80 kg/m²)
Power/mass: 0.093 hp/lb (0.204 kW/kg)

References

Notes

1 2 3 Francillon 1988, pp. 102–103.
↑ Francillon 1988, p. 103.
↑ Francillon 1988, p. 102.
↑ Francillon 1988, p. 104.
↑ Rumerman, Judy. "Douglas Aircraft Builds the DC-1 and DC-2." Archived September 19, 2002, at the Wayback Machine. Centennial of Flight, 2003. Retrieved: March 5, 2012.
↑ Francillon 1988, pp. 105–107.
↑ Bowers 1982, pp. 11–25.
↑ Bowers 1982, pp. 49-50.
↑ "Mayflower of the Air ready for President." Popular Science, May 1933, p. 713. Retrieved: March 5, 2012.
↑ "Flying Life Savers." Popular Mechanics Monthly, December 1933, pp. 900–903.
↑ Francillon 1988, pp. 110–111.

Bibliography

Bowers, Peter M. "Douglas Dolphin." Airpower, Volume 12, Number 6, November 1982.
Francillon, René J. McDonnell Douglas Aircraft since 1920, Volume 1. London: Putnam & Company Ltd., Second revised edition, 1988, 1979. ISBN 0-85177-827-5.

External links

Media related to Douglas Dolphin at Wikimedia Commons

Articles and topics related to the Douglas Dolphin

Douglas and McDonnell Douglas airliners
Piston-engined	M-1 M-2 M-3 M-4 Dolphin DF DC-1 DC-2 DC-3 DC-4E DC-4 DC-5 DC-6 DC-7
Jet-engined	DC-8 DC-9 (MD-80 MD-90 MD-95) DC-10 (MD-11)
Not developed	DC-7 (C-74 Globemaster) DC-7D DC-8 piston airliner Model 2067 (DC-9) Model 2229 (SST) MD-91X / -92X / -94X MD-12 / -XX DC-10-60 High Speed Civil Transport

Douglas military aircraft
Fighters	XFD XP-48 P-70 F3D Skyknight F4D Skyray F5D Skylancer XF6D Missileer
Ground attack	XA-2 A-20 A-24 A-26 A-33 A-1 Skyraider A-3 Skywarrior A-4 Skyhawk/A-4AR/A-4SU AC-47 DT T2D XT3D TBD Devastator SBD Dauntless BD XBTD XTB2D AD XA2D A3D A4D
Bombers	YB-7 YB-11 B-18 XB-19 XB-22 B-23 B-26 XB-31 XB-42 XB-43 B-66 DB-1 DB-2 DB-7 DB-8 DB-19 DB-73 Boston I/II/III/IV/V Digby I Havoc I/II DXD1
Observation	O-2 OD O2D O-31 O-35 O-38 O-43 YO-44 O-46 O-53 YOA-5
Patrol	PD P2D P3D
Reconnaissance	F-3
Transports	C-1 C-21 C-32 C-33 YC-34 C-38 C-39 C-41 C-41A C-42 C-47 C-48 C-49 C-50 C-51 C-52 C-53 C-54 C-58 UC-67 C-68 C-74 C-84 C-110 XC-112/YC-112 XC-114 YC-116 C-117 C-118 C-124 YC-129 C-133 C-9 C-24 RD R2D R3D R4D (R4D-2 & R4D-4) R5D JD R6D CC-129 Dakota I/III/IV Dakota II LXD1 PD.808 Skymaster I
Gliders	XCG-17
Training aircraft	BT-1 BT-2 XT-30
Experimental	DWC D-558-1 D-558-2 X-3

United States military transport aircraft designations, Army/Air Force and Tri-Service systems
Army/Air Force sequence (1925-1962)	C-1 C-2 C-3 C-4 C-5 C-6 C-7 C-8 C-9 C-10 C-11 C-12 C-13¹ C-14 C-15 C-16 C-17 C-18 C-19 C-20 C-21 C-22 C-23 C-24 C-25 C-26 C-27 C-28 C-29 C-30 C-31 C-32 C-33 C-34 C-35 C-36 C-37 C-38 C-39 C-40 C-41/A C-42 C-43 C-44 C-45 C-46 C-47/T C-48 C-49 C-50 C-51 C-52 C-53 C-54 C-55 C-56 C-57 C-58 C-59 C-60 C-61 C-62 C-63 C-64 C-65 C-66 C-67 C-68 C-69 C-70/A/B/C/D C-71 C-72 C-73 C-74 C-75 C-76 C-77/B-D C-78 C-79 C-80 C-81 C-82 C-83 C-84 C-85 C-86 C-87 C-88 C-89 C-90 C-91 C-92 C-93 C-94 C-95 C-96 C-97/KC-97 C-98 C-99 C-100 C-101 C-102 C-103 C-104 C-105 C-106 C-107 C-108 C-109 C-110 C-111 C-112 C-113 C-114 C-115 C-116 C-117 C-118 C-119 C-120 C-121/F C-122 C-123/A C-124 C-125 C-126 C-127 (I) C-127 (II) C-128 C-129 C-130/J C-131 C-132 C-133 C-134 C-135/KC-135 C-136 C-137 C-138¹ C-139¹ C-140 C-141 C-142
Tri-service sequence (1962-present)	C-1 C-2 C-3 C-4 C-5 C-6 C-7/B C-8 C-9 C-10 C-11 C-12 C-13¹ C-14 C-15 C-16¹ C-17 C-18 C-19 C-20A-D/F-H C-21 C-22 C-23 C-24 C-25 C-26 C-27/J C-28 C-29 C-30¹ C-31 C-32 C-33 C-34¹ C-35 C-36 C-37A/B C-38 C-39¹ C-40 C-41 C-42¹ C-43¹ C-44¹ C-45 C-46
Revived original sequence (2005-present)	C-143 C-144 C-145 C-146
Non-sequential designations	C-767 C-880
¹ Not assigned See also: AC-47 • AC-119 • AC-130 • DC-130 • EC-130 • HC-130 • KC-130 • LC-130 • MC-130 • WC-130 • CT-39 • CT-43

USN/USMC transport designations 1931–1962
Atlantic Aircraft	RA
Budd	RB
Curtiss	RC R2C⁴ R3C⁴ R4C R5C
Douglas	RD R2D R3D R4D R5D R6D
Bellanca	RE
Kinner	RK
Kreider-Reisner	RK² R2K
Martin	RM
Lockheed	RO R2O R3O R4O R5O R6O R7O-1/-2 to "V" (see below, at "Lockheed")
Stinson	RQ R2Q² R3Q
Fairchild	RQ R2Q R3Q² R4Q
Ford	RR
Sikorsky	RS
Northrop	RT
Lockheed	from "O" (see above, at "Lockheed") R6V R7V-1/-2 R8V
Convair	RY R2Y R3Y R4Y
¹ Not assigned ² Assigned to a different manufacturer's type ³ Sequence restarted ⁴ Assigned to a different class of aircraft

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