1937 saw the United States Navy looking for a replacement aircraft for its Curtiss SOC Seagull series of biplane floatplane aircraft. The USN was in the market for a more modern, monoplane-winged system that could fulfill the same floatplane reconnaissance role but also include better performance specifications and could operate from both land and water bases as needed. The undercarriage was, therefore, required to be interchangeable to suit the task at hand. The requirement was sent forth and proposals from various firms were entertained. Curtiss and Vought were invited to produce prototypes through a May 1938 contract. The Curtiss prototype was bestowed the developmental designation of XSO3C-1 while the Vought product took on the XSO2U-1 designation. XSO3C-1 first took to the air on October 6th, 1939. In the end, the Curtiss product won out and was ordered for production after some slight design revisions were ordered by the USN (including larger tail surfaces and upturned wingtips to aid in stability). The revised Curtiss Model 82A became the USN SO3C-1 for production under the early nickname of "Seagull". The chosen powerplant became the Ranger V-770-6 series engine.
Design of the SO3C was consistent with floatplane aircraft of the time. Most of her appearance was quite conventional-looking and revolved around a cylindrical fuselage mated to a localized network of floats under the aircraft fuselage and wings. With respect to the SO3C, the fuselage sat atop a large centralized float running nearly the length of the aircraft while each wing underside was supported by smaller stabilizing floats fitted to struts. The radial engine was fitted to the front of the fuselage and powered a two-bladed propeller assembly. The pilot sat immediately aft of the engine compartment under a glazed canopy that was usually left open for better visibility. The second crewmember, the designated observer (seated facing forward), took his position in a separate cockpit held to the rear of the aircraft, his position at the base of the vertical tail fin. Wings were mid-mounted and straight along the leading edge and tapered at the trailing edge, clipped at their tips (with a noticeable upturn to each tip end, needed to counter some initial instability problems in the prototype design), and fitted just aft of the pilot's position. The empennage was dominated by a large vertical tail fin curved to provide the SO3C a most identifiable appearance. Horizontal stabilizers were fitted to either side of the vertical tail fin base. Of note was the observer's heavily framed canopy - the assembly actually doubling as part of the forward portion of the tail fin base. This posed a problem to the aerodynamic qualities of the SO3C however, as the observer most often flew with the cockpit open. While this disrupted the airflow towards the rear of the aircraft, it offered the observer much better visibility when tracking surface targets from up high. Construction was of all-metal, with the exception being the fabric-covered control surfaces.
It's the Engine that Makes or Breaks an Aircraft
Power was supplied from the much-maligned Ranger XV-770-8 inverted V12 engine of 600 horsepower. The engine provided for a listed top speed of 172 miles per hour though cruising was limited to around 123 miles per hour. Range was roughly 1,150 miles (or about eight hours of flight time) and the aircraft's service ceiling was limited to 15,800 feet. The SO3C held an empty weight of 4,284lbs with a maximum take-off weight equal to 5,729lbs.
The Ranger XV-770 was a powerplant developed by the Ranger Aircraft Engine Division of the Fairchild Engine & Aircraft Corporation. The design appeared in 1931 and stemmed from the Ranger 6-440 series. The 6-440 was an in-line, air-cooled engine and produced by the company to power a series of training aircraft. In US military nomenclature, the 6-440 took on the designation of L-440. One of the first platforms to be fitted with the V-770 was a Vought XSO2U-1 Scout. Later, the engine was mated to the Curtiss SO3C Seamew. With the Seamew, the engine proved lacking and was found to be of generally poor return. Overheating proved a major sticking point particularly at low speed flying. Despite its limitations, the V-770 found a home in a few other military platforms including the Fairchild AT-21 trainer aircraft and the Bell XP-77 experimental fighter. Neither platform was produced in quantitative numbers, however, with the AT-21 reaching just 175 production units and the XP-77 being produced in just two prototypes.
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