Curtiss SB2C Helldiver: The Last Dive Bomber

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On the whole, American servicemen enjoyed an overwhelming superiority in the quality as well as the quantity of weaponry during World War II. The legendary reputations of the jeep, Douglas C-47, M-1 Garand rifle and North American P-51 Mustang, for example, were all well-deserved. Some American weapons fell short of expectations, however. One notable example was a dive bomber developed by Curtiss for the U.S. Navy, the SB2C Helldiver.

By and large, the aircraft that operated from the U.S. Navy’s aircraft carriers after 1942 were markedly superior to their Japanese counterparts. That opinion was shared by Britain’s Naval Air Arm, which operated numerous Grumman Wildcats, Hellcats and Avengers, as well as Vought Corsairs, from its carriers. It is significant, however, that the Royal Navy rejected the Helldiver for combat service, even while it continued to use the antediluvian Fairey Swordfish biplane torpedo bomber until the end of the war. Indeed, so disappointing was the SB2C’s performance that Captain Joseph J. Clark, commanding officer of USS Yorktown–one of the first carriers on which the aircraft was deployed–recommended that it be withdrawn from service and production canceled. It is also interesting to note that a Douglas SBD Dauntless, rather than an SB2C, has been preserved in the National Air and Space Museum in Washington, D.C., to represent a World War II-era Navy dive bomber.

The Curtiss SB2C was the last of a line of aircraft developed for the U.S. Navy specifically for the role of dive-bombing. That tactic was first used by a Marine aviator, Lieutenant (later Brig. Gen.) Lawson H.M. Sanderson, during operations in Haiti in 1919. Up until that time, aircraft had dropped their bombs from a level attitude. Marine fliers found that they could achieve a far greater degree of precision by releasing their bombs while aiming their planes directly at their targets in a steep dive of 70 degrees or more. Dive-bombing was officially adopted by the Navy as a regular part of its operational repertoire in 1928.

The U.S. Army Air Corps was convinced that it could hit any target from high altitude by means of level bombing, using precision optical bombsights. That belief seemed to be justified by Brig. Gen. William ‘Billy’ Mitchell’s highly publicized bombing of captured German warships in June 1921. Those targets, however, had been immobile. The Navy believed that a relatively small moving target, like a warship taking evasive action, would be virtually impossible to hit by level bombing. Naval aviators felt that pinpoint dive-bombing attacks, delivered simultaneously with coordinated low-level torpedo-plane attacks, would be the most effective method of dealing with an enemy fleet. By the same token, the Marines believed that dive-bombing afforded the best available way to provide close air support without endangering their own ground troops.

Another reason the dive-bombing technique held a greater appeal for the Navy than for the Army was the fundamental differences in the two services’ operational requirements. Army bombers could be built with unlimited size and load-carrying ability. If the power of available engines was insufficient, the Army could simply build the planes with two, three, four or more engines. If an airfield was too short for the operation of such large aircraft, the Army could simply lengthen the runway. Naval aircraft, in contrast, were restricted both in size and in the number of bombs they could carry because of the length of the aircraft carrier flight decks from which they operated. Naval aviation tactics therefore emphasized the accurate placement of a relatively small payload rather than smothering the target with as large a bombload as possible. The same principle held true for Marine aviation’s role in tactical close air support.

Initially, Navy scouting and fighter aircraft carried out dive-bombing missions. The first airplane designed specifically as a dive bomber was built by the Curtiss division of the Curtiss-Wright Corporation. Curtiss had been designing aircraft for the Navy since 1911, after Eugene Ely used one of Glenn H. Curtiss’ planes to make the first takeoff from a ship–the cruiser Birmingham–on November 14, 1910, followed by the first shipboard landing, on the cruiser Pennsylvania, on January 18, 1911. In 1928, Curtiss redesigned its F8C-1–a Marine version of the Falcon series of two-seat fighter-bombers–with a more compact and robust airframe, and the new 450-hp Pratt & Whitney R-1340 radial engine. In spite of the fact that prototype XF8C-2 crashed on December 3, 1928, just days after its first flight, Curtiss built an identical plane that satisfied the Navy enough to achieve production status as the F8C-4. It was the first of three Curtiss designs to be called Helldiver.

The name was pure hyperbole that originated with the Navy and Marine pilots who first developed the dive-bombing technique, which they demonstrated at airshows throughout the country during the 1930s. German World War I ace Ernst Udet was so impressed by one of those public dive-bombing demonstrations that in 1934 he persuaded the German air ministry to purchase two Curtiss Hawk II fighter-dive bombers for evaluation by the Luftwaffe. The eventual result was the development of the infamous Junkers Ju-87 Stuka. To the American public, the term ‘helldiver’ was associated with breathtaking power dives and dazzling displays of airmanship. Curtiss thought it only fitting that the name be applied to its purpose-built dive bomber, although it was not officially used by the Navy.

The first of an eventual 25 F8C-4s entered service with fighter squadron VF-1B aboard the carrier Saratoga in 1930. By then, however, they were already slower than the single-seat fighters they were intended to accompany into combat, and the first Helldiver was out of naval service by the end of 1931. Land-based F8C-5s used by the Marines were redesignated as O2C-1 observation aircraft and assigned to squadrons VO-6M at Quantico, Va., and VO-7M in Nicaragua–where they saw some use as dive bombers against Augusto César Sandino’s rebels until February 1933.

Adapted from fighters and scouting planes, the early dive bombers were not well-suited to their roles. As a result, the Navy and Marines developed a series of specialized aircraft during the 1930s that had no counterparts in the Army Air Corps. Since the dive bombers were required to perform the secondary function of reconnaissance, the Navy referred to them as scout bombers and gave them the designation SB.

Dive bombers had two features that distinguished them from other combat aircraft. One was the provision for dive brakes, usually in the form of split flaps, to retard the plane’s diving speed, giving the pilot more time to aim his bomb. The dive brakes also reduced stress on the airplane when it pulled out of its steep dive. The other unique feature was a special hinged bomb rack, or crutch, mounted under the fuselage, which swung the bomb clear of the propeller arc after it was released.

Curtiss’ second Helldiver evolved from the XF12C, a parasol monoplane two-seat fighter with enclosed cockpits and retractable landing gear. Designed under the direction of Raymond C. Blaylock, the XF12C-1 first flew in early 1933, but by the end of the year the Navy had selected the Grumman FF-1 and FF-2 biplanes for the two-seat fighter role. Curtiss redesignated the plane XS4C-1 and then XSBC-1, in hopes of having it accepted as a scout bomber. After the XSBC-1 crashed in September 1934 due to a failure in the wing-folding joint, the Navy contracted Curtiss to rebuild the prototype as a biplane. Curtiss did so and also redesigned the fuselage and tail surfaces to produce the XSBC-2. When the plane’s Wright Twin Whirlwind engine proved unreliable, the Navy ordered it replaced with a Pratt & Whitney R1535-82 Twin Wasp Jr., driving a Hamilton-Standard three-blade propeller. Tested in March 1936, the re-engined XSBC-3 had a maximum speed of 220 mph at 9,500 feet, a range of 635 miles carrying a 500-pound bomb, and a range of 1,190 miles after substituting a 45-gallon auxiliary fuel tank to use the plane in a scouting role. The new dive bomber was accepted for production on August 29, and the first SBC-3s–given the resurrected name of Helldiver by Curtiss, although once again the Navy did not officially refer to them as such–began entering service with VS-5 aboard the carrier Yorktown, VS-3 on Saratoga and VS-6 on Enterprise in late 1937.

After completing its 83-plane contract for the SBC-3, Curtiss introduced an improved version with a 950-hp Wright Cyclone R-1820-34 nine-cylinder radial engine in 1938, the extra power allowing the plane to carry a 1,000-pound bomb. The Navy bought 124 of that variant, the SBC-4, but in that same year Curtiss began designing a replacement. By that time, the conservative Naval Bureau of Aeronautics was finally coming to realize that the biplane’s days were numbered. In any event, the SBC was the last U.S. combat biplane. When the Navy ordered the first prototype of the SB2C monoplane on May 15, 1939, the plane was expected to represent a quantum leap in dive-bomber technology.

Uncouth individuals are sometimes accused of having been brought up in a barn. In the case of the SB2C, the analogy is appropriate. Because of Curtiss’ commitments to build P-40s for the Army Air Forces and Hawk 75 fighters for export, working space at their factories was at a premium. Therefore, most of the design and construction of the XSB2C-1 prototype was actually carried out in a cattle barn on the Ohio State University fairgrounds.

The XSB2C-1 had a length of 36 feet 9 inches and a wingspan of 49 feet 8 inches. It was a two-seat, single-engine monoplane with folding wings to facilitate storage aboard an aircraft carrier. The plane also possessed a feature unique for carrier-based aircraft at that period–an internal bomb bay. Again produced by Blaylock’s design team, the XSB2C-1 was built around a 1,500-hp Wright R-2600 Cyclone radial engine, the same engine that Grumman would use with more satisfactory results in the dive bomber’s stablemate, the TBF Avenger torpedo bomber.

By the time the prototype was assembled and flown for the first time at Curtiss’ plant in Buffalo, N.Y., on December 18, 1940, much of the world had been plunged into war. Although not yet involved in the conflict, the United States was beginning a massive rearmament program, both on its own behalf and on behalf of the Allies. Curtiss and the Navy were already committed to the large-scale production of the SB2C as a replacement for the Navy’s current dive bombers, the Vought SB2U Vindicator, the Douglas SBD Dauntless and Curtiss’ own SBC. Of the three types, the Vindicator and the SBD were regarded as rapidly approaching obsolescence. Although the SBC-4 was already considered obsolete, Curtiss modified 50 of them for use by the French navy. Delivered too late to see action in the Battle of France, the French SBC-4s sat out World War II in Martinique, where their possession by the Vichy French government provided a diplomatic headache for the U.S. State Department.

Although a massive production program was planned around the SB2C before the prototype ever took to the air, the airplane itself was already showing signs of trouble. Wind-tunnel tests had demonstrated that the plane’s stalling speed would be unacceptably high, and the wing had to be enlarged by 10 percent before the first flight was even attempted. There were also problems with the new R-2600 engine and the Curtiss Electric propeller. More important, the plane demonstrated serious handling problems. Because of the dangerous nature of carrier operations, superior low-speed handling and stalling characteristics were essential to shipboard aircraft. Yet the XSB2C’s low-speed stability and stall characteristics proved rather worse than average, even for a land-based plane. In February 1941, two months after its first flight, the prototype crashed on final approach, and further flight testing was delayed until October. Barely two months after that, on December 21, the rebuilt prototype was destroyed in another crash. The pilot had been forced to bail out when the starboard wing and tail collapsed during a test dive.

Under normal circumstances, the Navy would probably have cut its losses at that stage and canceled the SB2C. Exactly two weeks before the prototype’s second crash, however, Japanese carrier planes had attacked Pearl Harbor, and the United States–now officially involved in the conflict–was gearing up for a truly massive war production effort. A brand-new factory had been built by Curtiss in Columbus, Ohio, specifically to manufacture SB2Cs. The work force had been hired, raw materials allocated and numerous subcontractors lined up to produce dive bombers by the thousands.

At that stage, no one seriously doubted that Curtiss, with its wealth of previous experience, would be able to perfect the new dive bomber. When the United States entered World War II, Curtiss was mass-producing P-40 Warhawk fighters for the U.S. Army Air Forces and Allied air forces. It was also building the AT-9 twin-engine trainer and the C-46 Commando twin-engine transport. As for the Navy’s needs, in addition to the SB2C, Curtiss was developing the SO3C Seagull two-seat spotter seaplane for use on cruisers and battleships equipped with catapults. Despite the wide variety of work in which it was engaged at that time and the loss of the prototype, the Curtiss design staff persevered with its efforts to perfect the SB2C.

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Tags: 20th - 21st Century, Aircraft, Amphibious Operations, Aviation History, Historical Conflicts, World War II