The Curtiss SBC Helldiver was a pre-Second World War US Navy dive bomber that remained in service just long enough to see limited use in the early days of the war. It was also the last biplane to enter US Naval service.
The SBC designation had originally been given to a two-seat parasol monoplane with folding wings. This aircraft had made its maiden flight in 1933 as the XF12C-1, a carrier based fighter, before being redesignated as the XS4C-1 scout and then the XSBC-1 dive bomber. During a test in June 1934 a propeller blade broke off, and the aircraft was lost, although the test pilot escaped.
After the crash Curtiss asked for permission to produce a replacement aircraft. This would be the first genuine prototype for the SBC Helldiver. Given the designation XSBC-2, the new aircraft had little or nothing in common with the XSBC-1. It most obvious change was from monoplane to biplane, but the fuselage was also redesigned, both in shape and construction – the fuselage of the earlier aircraft had been partly constructed using the older welded tubular steel methods and partly as a metal monocoque. The new aircraft would have a full metal monocoque, and would be powered by a 700hp Wright XR-1510-12 radial engine.
This new design was given official approval, and made its maiden flight on 9 December 1935. The Wright engine proved to be unreliable, and was soon replaced with an equally powerful Pratt & Whitney R-1535-82 Twin Wasp Junior. With the new engine came a change of designation, to the XSBC-3.
After carrying out a series of tests on the XSBC-3, in August 1936 the US Navy placed an order for 83 SBC-3 Helldivers. These aircraft differed from the prototype in having an R-1535-94 engine, but were otherwise similar. They were armed with two 0.30in machine guns – one fixed forward firing and one flexible rear firing, and could carry a single 500lb bomb under the fuselage. Deliveries began on 17 July 1937, to scouting squadron VS-5. It was also used by VC-3 and VS-6, and remained in service until late in 1941. By December most of the remaining aircraft were being used as trainers at NAS Miami. Some remained in use as training aircraft until 1944.
The seventy-sixth production SBC-3 was used to produce the prototype XSBC-4. This saw the installation of a more powerful Wright R-1820-22 Cyclone engine. This increased the aircraft’s top speed by 10mph, but more importantly allowed the bomb load to be increased from 500lb to 1,000lb. An order for 58 SBC-4s was placed on 5 January 1938, and was followed by a second order for 31 aircraft and a third for 35, for a total of 124 aircraft. Deliveries began in March 1939, by which time the biplane SBC-4 was already verging on obsolescence. Most of the production aircraft went to the Naval Reserve, where they played an important part in the early training of potential pilots during the first two years of the war. A number were also used by carrier-borne squadrons, but by December 1941 only VB-8 and VS-8 on the USS Hornet were still operating the type, and they were reequipped before she entered combat.
One Marine Corps squadron, VMO-151, was still equipped with the SBC-4 in December 1941. After a brief period flying anti-submarine patrols off the west coast, in April 1942 the squadron departed for Samoa, arriving in May. They retained their SBC-4s until early in 1943, when they were finally replaced by Douglas SBD Dauntlesses. Fortunately for VMO-151 the Japanese did not come east to Samoa.
The only foreign order for the SBC was one for ninety aircraft for France, and was placed either late in 1939 or early in 1940. These aircraft were similar to the SBC-4, but with French 7.7mm Darne machine guns and self sealing fuel tanks. Work on the French aircraft progressed slowly, and at the end of May Roosevelt agreed to an urgent French request for the immediate release of some of the existing American SBC-4s. Fifty aircraft were taken from reserve bases, and preparations were made to transport them to France.
The fifty aircraft allocated to the French were transported to Canada (due to American neutrality laws they had to be towed across the border by tractors), where 45 of them were taken onboard the French aircraft carrier Bearn. While in mid-Atlantic news reached the Bearn of the French armistice, and she turned south and made for Martinique. Once there the Helldivers were unloaded, and after some diplomatic wrangling left to rot on the island.
Five of the French aircraft could not fit on the Bearn. Instead in August 1940 they were taken over by the British, as the Curtiss Cleveland. After their arrival in Britain they were evaluated, found to be unsuitable for use as combat aircraft, and instead used as instructional air frames. At least one of the Clevelands was used as a communications aircraft by No.24 “Commonwealth” Squadron.
Engine: Wright R-1820-34
Power: 850hp or 950hp (sources differ)
Wing span: 34ft
Length: 28ft 2in
Height: 10ft 5in
Empty weight: 4,552lb
Gross weight: 7,080lb
Maximum speed: 234 mph at 15,200ft
Cruising speed: 127mph
Initial climb rate: 1,860ft/ minute
Service ceiling: 24,000ft
Range: 405 miles
Armament: One fixed forward firing 0.30in gun, one flexible rear-firing 0.30in gun
Bomb load: One 500lb or 1,000lb under fuselage