The Curtiss SBC Helldiver was a two-seat scout bomber and dive bomber built by the Curtiss-Wright Corporation. It was the last combat military biplane procured by the United States Navy. Delivered in 1937, the aircraft became obsolete before the start of World War II.Wheeler 1992, p. 27.
Development There was controversy in the United States Navy's Bureau of Aeronautics (BuAer) in the early 1930s regarding two-seat fighter planes, monoplanes and the retractable undercarriage. In 1931, the Navy issued Design Specification No. 113, which detailed a requirement for a high-performance fighter with fixed undercarriage to be powered by the Wright R-1510Gunston p.199 or Pratt & Whitney's R-1535 radial engine.Gunston p.130 Seven companies submitted proposals and two companies, the Douglas Aircraft with their XFD-1Francillon pp.138–140 and the Chance Vought with their XF3U-1Moran p.59 were given contracts for one prototype each. Both of these aircraft were two-seat biplanes. The Navy then asked Curtiss to supply a prototype of a two-seat monoplane which was technically more advanced.
On 30 June 1932, BuAer signed a contract with Curtiss to design a two-seat monoplane with a parasol wing a retractable undercarriage and powered by a Wright R-1510-92 fourteen cylinder, two row, air-cooled radial engine driving a two-blade propeller. This fighter was designated XF12C-1.
Design The SBC was an all-metal, two-seat scout-bomber biplane with "I"-type interplane struts. It was the last combat biplane the Navy purchased and the last combat biplane manufactured in the United States. The two crewmen, pilot and radio operator/gunner, were housed in tandem cockpits enclosed by a sliding canopy and the turtle deck behind the rear cockpit could be folded down to allow the gunner to use his machine gun. The wings, rudder, elevators and flaps were fabric-covered. The main landing gear retracted into wheel wells in the fuselage just forward of the lower wing and the tailwheel retracted into the fuselage.Taylor p.111
XF12C-1 (Curtiss Model 73)
This aircraft was initially powered by a Wright R-1510-92 engine but this was unsuitable so the aircraft was re-engined with a Wright R-1670 fourteen cylinder, two row, air-cooled radial engine, which was also unsatisfactory. Both of these engines were prototypes and neither went into production. Finally, the Wright R-1820-80 nine cylinder, single row, air-cooled radial engine was installed and the resulting aircraft, designated XF12C-1 flew in 1933. Designed for aircraft carrier usage, the parasol wing folded back, a new feature for the Navy, for storage and the aircraft had an exposed tail hook for carrier landings. The first flight was in July 1933 but in September 1934, the parasol wing failed in the dive bomber tests.Swanborough p.162
XS4C-1 (Curtiss Model 73)
After testing, the XF12C-1 was rejected as a fighter, and on 7 December 1933 this aircraft was redesignated in the scout category as the XS4C-1 and re-engined with a Wright R-1820-80 radial engineJane pp.88d-92d driving a two-blade propeller. In its role as a scouting aircraft, bombing equipment for a bomb had to be designed and provided.
XSBC-1 (Curtiss Model 73)
In January 1934, the designation "Scout Bomber" (SB) was introduced and the aircraft was finally redesignated XSBC-1. In early 1934, flight tests, especially dive-bombing, began. On 14 June 1934, this aircraft crashed- attributed to wing failure- in Lancaster, New York, about from the Curtiss plant, during one of the tests, and it was destroyed.
XSBC-2 (Curtiss Model 77)
Curtiss-Wright made a proposal to the Navy to build one replacement aircraft which would be a staggered-wing biplane, would not have folding wings but would have leading-edge slots and the lower wing would have full-span flaps. It was an all-metal aircraft with fabric-covered control surfaces. It was powered by a Wright XR-1510-12 fourteen-cylinder, twin-row, air-cooled engine driving a constant speed Curtiss Electric three-blade propeller, and it featured an enlarged canopy, an enlarged vertical fin and rudder, and a retractable tail hook. The XSBC-2 had to engage in competitive tests against the Great Lakes Aircraft's XB2G-1Johnson pp.37–39 and the Grumman Aircraft Engineering's XSBF-1.Johnson pp.39–41 The XSBC-2 won and a contract for this aircraft was signed in April 1935; it made its first flight on 9 December 1935.
XSBC-3 (Curtiss Model 77)
The Wright XR-1510-12 engine in the XSBC-2 proved to be mechanically unreliable. In March 1936, this aircraft was re-engined with a Pratt & Whitney R-1535-82 fourteen-cylinder, twin-row, air-cooled engine driving a three-blade propeller and redesignated XSBC-3. With this new configuration, the Navy placed a production order.
SBC-3 (Curtiss Model 77A)
The major difference between the prototype XSBC-3 and the production aircraft was the engine. A contract for 83 aircraft was signed in August 1936 and deliveries began on 17 July 1937. The production aircraft were powered by an Pratt & Whitney R-1535-94 fourteen-cylinder, twin-row, air-cooled engine driving a three-blade propeller. Armament consisted of two machine guns, with one fixed gun in the right side of the fuselage, forward of the pilot, and a flexible gun in the rear cockpit. The aircraft had a bomb displacement swing located on the centerline of the fuselage for a bomb or a fuel tank.
XSBC-4 (Curtiss Model 77B)
The 76th SBC-3 was re-engined with a Wright R-1820-22 nine-cylinder, single-row, air-cooled radial engine driving a three-blade Hamilton Standard propeller and redesignated XSBC-4. The aircraft armament changed to one fixed machine gun in the right side of the fuselage, forward of the pilot, while keeping the flexible machine gun in the rear cockpit. With the more powerful engine, this aircraft could carry a bomb on the bomb displacement swing located on the centerline of the fuselage. A second SBC-3 was redesignated XSBC-4 and used for test work.
SBC-4 (Curtiss Model 77B)
The contract for 124 production aircraft of the XSBC-4 was signed on 5 January 1938 and deliveries began in March 1939 to April 1941.
Operational history
U.S. Navy
In August 1936, the Navy signed a contract for 83 SBC-3s (Curtiss Model 77A). Delivery of the SBC-3s to the fleet began on 17 July 1937 when the first aircraft were issued to Scouting Squadron Five (VS-5) serving in USS Yorktown (CV-5) however, Yorktown was not commissioned until 30 September 1937 and the ship then began sea trials. On 10 December 1937, VS-5 went aboard Yorktown and served aboard her until replaced by Douglas SBD-3 Dauntlesses in 1940.
By June 1938, three of the five scouting squadrons serving in aircraft carriers were equipped with SBC-3s while the other two were equipped with Vought SBU-1s. The three ships with SBC-3s were:
USS Enterprise (CV-6): Fighting Squadron Six (VF-6) had an SBC-3 and VS-6 had 20 Helldivers. USS Saratoga (CV-3): Bombing Squadron Three (VB-3) had one SBC-3, VF-3 had an SBC-3 and VS-3 had 21 Helldivers. USS Yorktown (CV-5): VS-5 had ten SBC-3s.Larkins, U.S. Navy p.229
One of the SBC-3s was kept at the factory and redesignated XSBC-4 (Curtiss Model 77B). This aircraft was re-engined with the Wright R-1820-22 nine cylinder, single row, air-cooled radial engine.
The initial contract for 58 SBC-4s was signed on 5 January 1938. This was followed by two additional contracts, one for 31 Helldivers on 27 July 1938 and the third contract for 35 aircraft on 13 August 1938. Total aircraft contracted for was 124. The aircraft were powered by the Wright R-1820-24 engine.
The first squadron to receive the SBC-4s was VS-2 in USS Lexington (CV-2) replacing the Vought SBU-1s. By 26 June 1939, VS-2 was fully equipped with 21 aircraft. This was the only aircraft carrier that flew the SBC-4 and they were replaced by Douglas SBD-2 and -3 Dauntlesses in 1941.
Because of the expanding aviation training program, the majority of SBC-4s, and other training aircraft, were assigned to Naval Reserve Air Bases (NRABs) to allow reserve Navy and Marine airmen, assigned to reserve scouting squadrons (VS and VMS), to maintain their proficiency. By June 1940, 11 NRABs had SBC-4s as follows:
NRAB Anacostia, District of Columbia: 3 SBC-4s assigned to VS-6R and VMS-3R, NRAB Boston, Massachusetts: 3 SBC-4s assigned to VS-1R, VS-2R and VMS-1R, NRAB Detroit, Michigan: 3 SBC-4s assigned to VS-8R and VMS-5R, NRAB Glenview, Illinois: .4 SBC-4s assigned to VS-9R, NRAB Kansas City, Kansas: 4 SBC-4s assigned to VS-12R and VMS-10R, NRAB Long Beach, California: 4 SBC-4s assigned to VS-13R, VS-14R and VMS-7R, NRAB Minneapolis, Minnesota: 3 SBC-4s assigned to VS-10R and VMS-6R, NRAB New York, New York: 4 SBC-4s assigned to VS-3R, VS-4R and VMS-2R, NRAB Oakland, California: 4 SBC-4s assigned to VS-15R and VMS-8R, NRAB Seattle, Washington: 4 SBC-4s assigned to VS-16R and VMS-9R, NRAB St. Louis, Missouri: 3 SBC-4s assigned to VS-11RLarkins, U.S. Navy p 275.
As time passed, the Navy acquired newer, more modern aircraft and the SBC-3s were replaced by the Douglas SBD Dauntless. By 7 December 1941, the U.S. Navy and Marine Corps had 69 SBC-3s and 118 SBC-4s in the inventory based at NASs, NRABs and the Naval Aircraft Factory (NAF) in Philadelphia, Pennsylvania. The largest number were at NAS Miami, Florida, where they were used for intermediate and dive bombing training.
In December 1941, the SBCs were based at:
NAF, Philadelphia, Pennsylvania: 1 XSBC-1 and 1 SBC-3, NAS Corpus Christi, Texas: 34 SBC-4s, NAS Miami, Florida: 55 SBC-3s, NAS Norfolk, Virginia: 4 SBC-3s and 10 SBC-4s, NAS San Diego, California: 9 SBC-3s and 11 SBC-4s, Naval Mission, Lima, Peru: 1 SBC-4, USS Hornet (CV-8) Bombing Squadron Eight (VB-8): 19 SBC-4s, Scouting Squadron Eight (VS-8): 20 SBC-4sLarkins U.S. Navy pp.309–310
Hornet was undergoing sea trials in the Atlantic on 7 December and the two squadrons kept their SBC-4s until the ship sailed to San Diego, California in March 1942. At that time, the two squadrons had transitioned to the SBD-3 Dauntless and she became the last aircraft carrier to operate the SBC.
An additional 50 SBC-4s, originally ordered by the French, were built between February and May 1941 to replace those sent overseas. The major change was replacing the fuselage fuel tank with a self-sealing fuel tank. The last SBC-4 was delivered in May 1941.
By 1944, the SBC-3s were no longer needed and they were stricken from the inventory. The longest to survive were 12 aircraft at NAS Jacksonville, Florida, which were stricken on 31 October 1944.
U.S. Marine Corps
The U.S. Marines received one SBC-3 in 1938 and which was assigned to Marine Fighter Squadron Two (VMF-2, redesignated VMF-211 on 1 July 1941) at NAS San Diego, California.Larkins, U.S. Marines p.70 and 75. It was sent to the Battle Fleet Pool in June 1939.
In January 1940, the Marine Corps had four SBC-4s.Larkins, U.S. Marines pp 86 and 87. Two were based at Marine Corps Air Station (MCAS), Quantico, Virginia; one was assigned to VMF-1 (redesignated VMF-111 on 1 July 1941) and the second, the XSBC-4, was assigned to Marine Utility Squadron One (VMJ-1 redesignated VMJ-152 on 7 July 1941). The other two aircraft were based at NAS, San Diego, California; one SBC-4 was assigned to VMF-2 and the second to VMJ-2 (redesignated VMJ-252 on 1 July 1941).
On 7 December 1941, the Marine Corps had 23 SBC-4s in their inventory. Twelve of them were assigned to a Marine observation squadron (VMO):
MCAS Quantico, Virginia: 1 XSBC-4 and 5 SBC-4s, NAS San Diego, California: 5 SBC-4s, and VMO-151, MCAS Quantico, Virginia: 12 SBC-4sSherrod p.33.