Curtiss 71 / SOC Seagull
1937 saw the United States Navy looking for a replacement aircraft for its Curtiss SOC Seagull series of biplane floatplane aircraft. The requirement was circulated to US manufacturers in early 1933, resulting in proposals from Curtiss, Douglas and Vought, but it was the XO3C-1 prototype, company-designated Curtiss Model 71, ordered on 19 June 1933 and first flown in April 1934, which was ordered into production as the SOC-1 (Model 71A). This changed official designation reflected the combination of scout and observation roles.
When first flown the prototype was equipped with amphibious landing gear, twin main wheels being incorporated in the central float. However, standard production aircraft were built as floatplanes, with non-retractable tailwheel landing gear optional; in any event they were easily convertible from one configuration to the other. Construction was mixed, with the foldable wings and tail unit of light alloy, a welded steel-tube fuselage structure, and a mixture of light alloy and fabric covering. The pilot and gunner/observer were accommodated in tandem cockpits, enclosed by a continuous transparent canopy with sliding sections for access. To provide a maximum field of fire for the flexibly-mounted gun in the rear cockpit, the turtleback could be retracted.
Deliveries of the first SOC-1 production aircraft began on 12 November 1935. These were powered by Pratt & Whitney R-1340 Wasp engines, and the first squadrons to become fully equipped with the type comprised Scouting Squadrons VS-5B/ -6B/ -9S/ -10S/ -11S. Production of 135 SOC-1s was followed by 40 examples of the SOC-2 (Model 71B) with wheeled landing gear, detail improvements and R-1340-22 Wasp engines. A total of 83 examples of the SOC-3 (Model 71E) was built, these being generally similar to the SOC-1. SOC-2s and SOC-3s, after modification to install arrester gear during 1942, became redesignated SOC-2A and SOC-3A respectively. Curtiss also built three aircraft virtually the same as the SOC-3 for service with the US Coast Guard: these SOC-4 (Model 71F) aircraft were acquired by the US Navy in 1942 and equipped with arrester gearto bring them up to SOC-3A standard. In addition to the SOC Seagulls built by Curtiss, 44 were produced by the Naval Aircraft Factory at Philadelphia, Pennsylvania. Basically the same as the Curtiss-built SOC-3, these were designated SON-1 or, if fitted with arrester gear, SON-1A.
Following termination of SOC production in early 1938, Curtiss became involved in the development and manufacture of a successor, designated SO3C Seamew. However, when the operational performance of the Seamew proved unsatisfactory it was withdrawn from first-line service; all available SOCs then reverted to operational status, continuing to fulfil their appointed role until the end of the war.
Curtiss SOC-1 Seagull
Engine: 1 x Pratt & Whitney R-1340-18 Wasp, 447kW / 600 horsepower.
Wingspan: 10.97 m / 35 ft 12 in
Wing area: 31.77 sq.m / 341.97 sq ft
Length: 8.08 m / 26 ft 6 in
Height: 4.50 m / 14 ft 9 in
Maximum Speed: 157mph (253kmh; 137kts)
Cruise speed: 214 km/h / 133 mph
Maximum Range: 954miles (1,535km)
Rate-of-Climb: 1,000ft/min (305m/min)
Service Ceiling: 14,895ft (4,540m)
1 x 0.30 cal (7.62mm) fixed, forward-firing machine gun.
1 x 0.30 cal (7.62mm) trainable machine gun in flexible mount in rear cockpit.
2 x 100lb bombs held underwing.
Empty Weight: 3,508lbs (1,591kg)
Maximum Take-Off Weight: 5,437lbs (2,466kg)