Douglas VTB (SD-114-6)
Carrierborne Attack Aircraft Proposal
The Douglas VTB - or proposal SD-114-6 - was drawn up to satisfy a pre-World War 2 United States Navy requirement for a carrierbased attacker.
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In preparation for the oncoming war (that was World War 2) in March of 1939, the United States Navy (USN) drew up plans for a new, all-modern carrier-based attacker under Specification SD-114-6. More to the point, the requirement looked for a modern navy-centric "torpedo bomber" capable of hauling anti-ship ordnance over water across vast distances. The type was seen as a successor to the aging Douglas TBD "Devastator" (detailed elsewhere on this site) and was to encompass a three man operating crew while being capable of reaching altitudes of around 30,000 feet, out to range of 1,000 miles, and hauling a war load of around 1,500lb (conventional drop bombs or a single, air-released torpedo).
While the requirement was eventually filled by the Grumman "Avenger" carrierborne dive bomber (also detailed elsewhere on this site), there were several interesting candidates proposed by some of the usual industry players of the period - this to include the "VTB" by long-time airplane-maker Douglas (Douglas had much to lose on this effort for the very aircraft under consideration for replacement was its own Devastator - a torpedo bomber with origins in 1935 and only 130 taken into service with the USN).
The VTB followed some of the form and function of the existing Devastator but, in tune with the times, engineers elected for a much more streamlined fuselage with the wing mainplanes mid-mounted along the sides of the fuselage and set well-forward of midships. These members were straight-lined with clipped tips and noticeable sweep was given only to their trailing edges. The engine was to take up its usual spot at the nose and turn a three-bladed propeller unit. The cockpit, to house the complete team of three (pilot, bombardier, and radioman/gunner) under a heavily-framed, greenhouse-style canopy, was also seated ahead of midships to place much of the mass of the aircraft forward. The fuselage was to taper as its lines moved along the tail section to which a single clipped vertical fin would be affixed in conjunction with low-set horizontal planes. A "tail-dragger" undercarriage would provide the needed ground-running capability with only the main leg members being retractable. An arrestor hook can be assumed as standard equipment for this carrier-based warplane.
For power, the VTB was to carry the Wright R-2600 "Twin Cyclone" air-cooled radial engine of 1,600 horsepower output - radial engines being heavily favored by the USN service.
Proposed standard armament centered on 2 x 20mm autocannons, one fitted to each wing, and 2 x 0.30 caliber or 0.50 caliber machine guns set aft of the engine cowling and just ahead of the pilot's position. All of these guns would be controlled by the pilot directly. Optional armament, encompassing drop bombs or a single torpedo, would have been held in an internal bomb bay at the ventral / belly section of the fuselage. While the design brochure showed no defensive armament /turret as part of the suite of this aircraft, it most likely would have fitted some form of weapon facing the rear on a trainable mounting for the radioman-machine gunner to manage.
Dimensions, as drawn up, included an overall length of 38.2 feet and a wingspan of 47 feet. In keeping with other naval warplanes of the period, the VTB was to have some sort of wing-folding capability for storage aboard American naval carriers - bringing its overall span down considerably. The wings were to fold, along an internal hinge system, near their midway point and outboard of the wing autocannon weapons.
At any rate, the VTB was not advanced outside of its design brochure. The Model 40 offered by Grumman went on to be further developed and accepted into service as the "Avenger" and nearly 10,000 of its kind were produced for the war effort.