Curtiss SOC Seagull
|Seagull seaplane configuration in flight|
|First flight||April 1934|
|Introduction||12 November 1935|
|Primary users||United States Navy
United States Coast Guard
United States Marine Corps
|Number built||322 (258 by Curtiss, 64 by the NAF)|
The Curtiss SOC Seagull was a United States single-engined scout observation biplane aircraft, designed by Alexander Solla of the Curtiss-Wright Corporation for the United States Navy. The aircraft served on battleships and cruisers in a seaplane configuration, being launched by catapult and recovered from a sea landing. The wings folded back against the fuselage for storage aboard ship. When based ashore or on carriers the single float was replaced by fixed wheeled landing gear.
Curtiss delivered 258 SOC aircraft, in versions SOC-1 through SOC-4, beginning in 1935. The SOC-3 design was the basis of the Naval Aircraft Factory SON-1 variant, of which the NAF delivered 64 aircraft from 1940.
Design and development
The SOC was ordered for production by the United States Navy in 1933 and first entered service in 1935. The first order was for 135 SOC-1 models, which was followed by 40 SOC-2 models for landing operations and 83 SOC-3s. A variant of the SOC-3 was built by the Naval Aircraft Factory and was known as the SON-1.
The first ship the SOC was assigned to was the USS Marblehead in November 1935; by the end of the decade, the SOC had replaced its predecessor throughout the fleet. Production came to an end in 1938. By 1941, most battleships had transitioned to the Vought OS2U Kingfisher and cruisers were expected to replace their aging SOCs with the third generation SO3C Seamew. The SO3C, however, suffered from a weak engine and plans to adopt it as a replacement were scrapped. The SOC, despite being a craft from an earlier generation, went on to credibly execute its missions of gunfire observation and limited range scouting missions.
Through the first six months of naval service, the SOC was known as the XO3C-1, The designation was changed to SOC when it was decided to merge its scouting and observation roles. The SOC was not called the Seagull until 1941, when the U.S. Navy began the wholesale adoption of popular names for aircraft in addition to their alpha-numeric designations. The name 'Seagull' had earlier been given to two civil Curtiss aircraft, a Curtiss Model 18 and a Model 25, both converted Curtiss MF flying boats.
When operating as a seaplane, returning SOCs would land on the relatively smooth ocean surface created on the sheltered side of the vessel as it made a wide turn, after which the aircraft would be winched back onto the deck.
When the SOC had been replaced by the OS2U Kingfisher, most remaining airframes were converted into trainers, and were used until 1945. But in a strange twist of history, with the failure of the Curtiss SO3C Seamew, many SOCs in second line service were returned to frontline units starting in late 1943 and saw service aboard warships in the combat zone for the rest of World War II. This is one of the few instances in aviation history of an older aircraft type that was retired or sent to second line service, replacing the new aircraft type, that was supposed to replace it. 
- XO3C-1 (Curtiss Model 71)
- Prototype aircraft, powered by 550 hp (410 kW) Pratt & Whitney R-1340-12 engine. One built, redesignated XSOC-1 on 23 March 1935.
- SOC-1 (Curtiss Model 71A)
- Initial production version, with 500 hp R-1340-18 engine enclosed in NACA cowling. Interchangeable float and wheeled undercarriage. 135 built.
- SOC-2 (Curtiss Model 71B)
- Minor changes, with R-1340-22 engine. 40 built. Wheeled undercarriage only.
- XSO2C-1 (Curtiss Model 71C)
- Improved version. One prototype only, no production.
- SOC-3 (Curtiss Model 71E)
- Similar to SOC-2, but with interchangeable undercarriage. 83 built by Curtiss as SOC-3 with further 64 built by the Naval Aircraft Factory as the SON-1.
- All SOC-4s were transferred to the U.S. Navy in 1942 (BuNo 48243, 48244, 48245, respectively), which modified them SOC-3A standard, meaning the fitting of a deck arrester gear.
- (Curtiss Model 71F): The U.S. Coast Guard acquired the final three SOC-3 Seagulls produced by Curtiss in 1938 and these were designated as SOC-4s. They were assigned the USCG call numbers V171, V172, and V173.
- One built for evaluation based on the SOC-3, but with a 5-foot fuselage stretch and powered by a R-1340-35.
- SOC-3 aircraft produced by the Naval Aircraft Factory, 64 built.
Specifications (SOC-1 floatplane)
Data from War Planes of the Second World War, Volume Six: Floatplanes
- Crew: two, pilot and observer
- Length: 31 ft 5 in (9.58 m)
- Wingspan: 36 ft 0 in (10.98 m)
- Height: 14 ft 9 in (4.50)
- Wing area: 342 ft² (31.8 m²)
- Airfoil: NACA 0010 (upper wing); NACA 2212 (lower wing)
- Empty weight: 3,788 lb (1,722 kg)
- Loaded weight: 5,437 lb (2,471 kg)
- Powerplant: 1 × Pratt & Whitney R-1340-18 single-row, nine-cylinder, air-cooled radial engine, 550 hp (410 kW)
- Maximum speed: 165 mph (143 knots, 266 km/h) at 5,000 ft (1,500 m)
- Cruise speed: 133 mph (116 knots, 214 km/h)
- Stall speed: 55.9 mph (90 km/h)
- Range: 675 mi (587 nmi, 1,086 km)
- Service ceiling: 14,900 ft (4,540 m)
- Rate of climb: 915 ft/min (4.64 m/s)
- Wing loading: 15.9 lb/ft² (77.7 kg/m²)
- Power/mass: 0.10 hp/lb (0.17 kW/kg (9.6 lb/hp))
- Guns: 1× fixed, forward firing 0.30 in (7.62 mm) Browning M2 AN and 1× flexible mounted rear-firing 0.30 in (7.62 mm) Browning M2 AN machine gun
- Bombs: 650 lb (295 kg) of bombs
RAdm Ernest King in front of his SOC-1, 1936
A SOC-2 launching from the USS Montpelier
SOCs on catapults of a Brooklyn class cruiser, note hangar hatch below.
USS Tuscaloosa (CA-37) hoists an SOC, September 1941.jpg
- Related development
- Aircraft of comparable role, configuration and era
- Related lists
- US Navy History website
- Bowers 1979, pp. 339-340.
- Bowers 1979, pp. 178, 183, 627.
- World War II Database/SOC Seagull
- Munson 1985, p. 79.
- Donald 1997, p. ?.
- Bowers 1979, pp. 341, 345.
- Bowers 1979, p. 342.
- Bowers 1979, p. 343.
- Bowers 1979, p. 345.
- Larkins 1967, p. 12.
- A History of Coast Guard Aviation by Robert Scheina
- Green 1962, p. 160.
- Larkins 1967, p. 9.
- Bowers, Peter M. Curtiss Aircraft, 1907-1947. London: Putnam & Company Ltd., 1979. ISBN 0-370-10029-8.
- Donald, David. The Complete Encyclopedia of World Aircraft. Orbis Publishing Limited, 1997. ISBN 0-7607-0592-5.
- Green, William. War Planes of the Second World War, Volume Six: Floatplanes. London: Macdonald & Co. (Publishers) Ltd., 1962.
- Larkins, William T. The Curtiss SOC Seagull (Aircraft in Profile number 194). Leatherhead, Surrey, UK: Profile Publications Ltd., 1967. OCLC 43484775.
- Larkins, William T. Battleship and Cruiser Aircraft of the United States Navy. Atglen, PA: Schiffer Books, Inc., 1996. ISBN 0-7643-0088-1. OCLC 35720248.
- Mondey, David. The Hamlyn Concise Guide to American Aircraft of World War II. London: Chancellor Press, 1996. ISBN 1-85152-706-0.
- Munson, Kenneth. US Warbirds, From World War 1 to Vietnam. New York: New Orchard, 1985. ISBN 978-1-85079-029-7.
- Swanborough, Gordon and Peter M. Bowers. United States Navy Aircraft since 1911. London: Putnam & Company Ltd., Second edition, 1976. ISBN 0-370-10054-9.
|Wikimedia Commons has media related to Curtiss SOC Seagull.|
- Site on the SOC by Commander Ralph "Kaiser" Wilhelm, USN (Ret.)
- Official U.S. Navy Historical Center site on the SOC with images.
- Site on the SOC using material by William Larkins