Curtiss SBC Helldiver

The Curtiss SBC Helldiver was a two-place scout bomber built by the Curtiss-Wright Corporation. It was the last military biplane procured by the United States Navy. Delivered in 1937, it became obsolete even before World War II and was kept well away from combat with Axis fighters.

Design and development
In 1932, the U.S. Navy gave Curtiss a contract to design a parasol two-seat monoplane with retractable undercarriage and powered by a Wright R-1510 Whirlwind, intended to be used as a carrier-based fighter. The resulting aircraft, designated the XF12C-1, flew in 1933. Its chosen role was changed first to a scout, and then to a scout-bomber (being redesignated XS4C-1 and XSBC-1 respectively), but the XSBC-1's parasol wing was unsuitable for dive bombing. A revised design was produced for a biplane, with the prototype, designated the XSBC-2, first flying on 9 December 1935.

The SBC-3 the initial production model was powered by a Pratt & Whitney R-1535 Twin Wasp Junior. The SBC-3 began operational service in 1938. A total of 83 SBC-3s were built.

The SBC-4 was powered by a Wright R-1820 Cyclone. The SBC-4 entered service in 1939.

Operational history
The Navy took deliveries of the new aircraft in mid-1937 with the first batch of carrier-based aircraft going to USS Yorktown (CV-5), but time and technology caught up to the advanced biplane. It was relegated to hack duties and service as an advanced trainer for training units in Florida. The last aircraft was struck from the Navy roster in October 1944.

Foreign interest for the concept of a dive bomber led to orders abroad. 174 SBC-4s were built including 50 SBC-4s that were delivered to the French Navy. Five of the French order were delivered to the British Royal Air Force who named them the Curtiss Cleveland Mk.I.

The SBC Helldiver was not destined to have a long U.S. service life, but its impact was felt as the type made a lasting contribution by serving as the key platform in developing dive bombing tactics and honing aircrew skills crucial to winning the war in the Pacific.

French SBC-4s
The 50 SBC-4s delivered to France were actually aircraft already in service with the United States Navy. On 6 June 1940, Naval reservists received orders to immediately fly 50 SBC-4s to the Curtiss factory at Buffalo, New York. At Buffalo, a Bureau of Aeronautics inspector informed the pilots their aircraft were to be flown to Halifax, Nova Scotia to be loaded aboard the French aircraft carrier FRENCH AIRCRAFT CARRIER Béarn. From Buffalo to Halifax, the reserve pilots were officially employees of Curtiss. Curtiss paid each pilot $250 plus return rail fare from Halifax to Buffalo. All navy insignia were removed from their uniforms or taped over. Upon return to Buffalo, the pilots went back on Navy orders for return to their home bases.

Curtiss employees worked overtime to remove and replace all gear and instruments marked BUAERO, BUSHIPS or BUORD. The Navy .30 in machine guns were replaced by .50 in guns and the aircraft were repainted in camouflage colors with the French tricolor on the rudders. The hasty conversion did not allow time for adequate checkout of replacement instruments. Weather deteriorated with rain and fog over most of the route from Buffalo to Halifax. The Bureau of Aeronautics inspector temporarily halted flights after one of the first pilots was killed in a crash between Buffalo and Albany.

When the weather improved, sections of three aircraft were dispatched from Buffalo to Burlington, Vermont, then over the White Mountains (New Hampshire) to Augusta, Maine, and then to Houlton, Maine. After landing at Houlton, the aircraft were towed down a road across the Canadian border for takeoff from a New Brunswick farm pasture to avoid legal implications of flying over the border. The surviving 49 aircraft flew over the Bay of Fundy and 44 of them were loaded aboard Béarn at Dartmouth, Nova Scotia together with 21 P-36 Hawk fighters and 25 Stinson 105s for the French Armée de l'Air  and five Brewster Buffalos for Belgium. France surrendered while Béarn was crossing the Atlantic; she turned south to Martinique, where the SBC-4s corroded in the humid Caribbean climate while waiting on a hillside near Fort-de-France. The five SBC-4s remaining in Canada when France surrendered were taken over by the United Kingdom and were used as ground-instructional airframes.

Variants

 * XF12C-1
 * Prototype parsol-wing fighter powered by a 625 hp R-1510-92 radial; one built, later converted into biplane as the XS4C-1.


 * XS4C-1
 * Prototype was re-designated in the Scout category before being re-designated again as the XSBC-1.


 * XSBC-1
 * Prototype re-designated from XS4C-1, a biplane with a R-1820-80.


 * XSBC-2
 * Redesigned biplane based on XSBC-1 and powered by a 700 hp XR-1510-12; one built.


 * XSBC-3
 * XSBC-2 re-engined with a 750 hp R-1535-82.


 * SBC-3
 * Production variant with an 825 hp R-1534-94; 83 built.


 * XSBC-4
 * SBC-3 re-engined with a 950 hp R-1820-22; one conversion.


 * SBC-4
 * Production variant with a 950 hp R-1820-34; 174 built, including 50 transferred to the French Navy.


 * Cleveland I
 * British designation for five SBC-4s.

Operators
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 * French Navy
 * Royal Air Force
 * United States Marine Corps
 * United States Navy