Profile Publications No. 124 The Curtiss SB2C-1 Helldiver

The Curtiss SB2C-1 Helldiver “~The S B 2 C - I first saw combat with VB-17 on the U.S.S. {Junker Hill, in a raid baRon a u lon l l t l i November, 1943. A group o f the Bunker Mill H e lld ive rs are seen hereon another mission, in January /944. Note under wing bombs mounted on nearest aircraft also modified twin ¦30 calibre rear armament in place o f the ¦50 calib remounting origin ally Jilted .(Photo: U.S.N./National Archives) Summing up the air inaction the Battle of the Philippine Sea, l9-20th June, 1944, the eminent naval historian, Samuel Eliot Morison has written, ..the new Hell­ diver (SB2C) was outshone by the two remaining squadrons of Dauntless dive bombers (SB D ).Unfortunately ,nothing could be done about it since the production lines were rolling with Helldivers: here the Dauntless fought her last battle.” This was the first major Pacific inaction which SB2C's equipped the majority of the dive bomber squadrons in the participating carrier air groups. Only three months prior to this action, the Truman Committee published its aircraft report on the basis of testimony taken the previous year. Particular attention was directed to the Curtiss-Wright Corporation and the fact that no combat-usable SB2C-1 dive bombers had yet been delivered to the Navy. Production of its Army equivalent was no better, and furthermore, dive bombers by then were considered of little use for Army Air Force action. It remains for later versions of the Helldiver to fully live up to the Curtiss-Wright ads. which the Truman Committee so thoroughly condemned. But the story of the SB2C-1 series is not all black in the final analysis it is the story of overcoming almost insurmountable obstacles under conditions that changed drastically with the fast- paced events of the period. TH F XSB2C-1 The story of the SB2C began early in 1938 when the U.S. Navy's Bureau of Aeronautics prepared the require­ments for anew scout/dive bomber aircraft. Factors considered included the new air-cooled radial engines then underdevelopment, fitting a maximum number of air­planes on the carrier decks, and the desire for increased speed, range, armament and bomb carrying capability. De-icing equipment, folding monoplane wings, retractable landing gear and provisions for armour installation were all considered necessary in the design. Fleet reaction was that folding wings were undesirable and that fixed landing gear was preferred, but they more than agreed with the need for heavier armament. Bureau engineers and officers studied these reactions and decided togo ahead as planned. Among other features considered desirable was that two of these aircraft could be handled on a 40 by 48 foot elevator with at least one foot clearance all around. In response to the August 1938 invitations to submit entries for the design competition, six companies submitted a range of designs by the December closing date. Only the Curtiss and Brewster designs proposed to use the new larger radial engines, specifically the 1700 h.p. Wright R-2600, and even the best of their designs only met mini­mum requirements. In addition, certain changes were considered necessary. With the condition that these changes be made, Brewster and Curtiss were selected to build XSB2A-I and XSB2C-I prototypes respectively, notification being made in January 1939. Design of these two aircraft was similar in many respects: folding wings mounted far enough upon the fuselage to permit bomb carriage in an internal bomb bay, inward retracting main landing gear, cleanly cowled engines, split trailing edge dive flaps, and all metal con­struction except for fabric covered control surfaces. Curtiss' Design 84 went further toward meeting the “two airplanes on the elevator" requirement and was almost a stubby airplane. Its typical Curtiss planform shapes were carried over from the P-40 and other Curtiss designs and the aft fuselage arrangement was derived from the SBC series. Events of the design period were not unlike those for any new aircraft design. As the design developed in detail, problems arose and had to be solved, and BuAer was also to find some changes necessary in its planning. Excessive weight was a major problem throughout the design period, as was the aft gun installation. Curtiss engineers, under Project Engineer Raymond Blaylock, had the design well underway when the contract was finally signed in May 1939. In addition to XSB2C-1 BuNo 1758, the contract called for the usual static tests, design data and flight demonstration tests. Mockup inspection took place in late May with the principal changes recommended for, and subsequently made in, the armament installation: deletion of the alternate provisions for -50 forward firing fuselage guns in place of the regular instal­lation of two -30's, and major redesign of the power driven flexible gun installation. Two subsequent mockups of the rear gun installation were required before the design was considered acceptable in Februay 1940. In July a major design setback was encountered. Wind tunnel and experimental full scale flight testing showed that the wing maximum lift coefficient would be lower than had been estimated, giving an excessively high stall speed. After considering alternate solutions (extending the leading edge slats to full span, drooping the ailerons, and increasing wing area), the latter action was taken, with an increase from 385 to 422 square feet. The penalty in top speed was accepted and the entire wing redesigned. Dive brakes were also investigated thoroughly since the brake-open dive speed was higher than desired. Con­clusive action was not taken, except to provide variable opening angles of the split diving and landing flaps for flight evaluation. Magnesium alloy was used for many items to save weight, but most of this had to be replaced with aluminium alloys before the airplane was ready for flight. Several large forgings were designed for the wing carry-through area as another weight saving measure, along with reductions in size of some structural members. Redesign of the cannon installation in each towing accommodate a different type -20 mm. cannon, delay in engine qualification and delivery, and incorporation of changes made necessary by failures in static testing further delayed the prototype programme. 3
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