CT-1, PT-2, Fokker FT, STOUT ST-1, BLACKBURN SWIFT
While still without a real torpedo plane at the war’s end, the Navy did have the Curtiss R-6, an unarmed twin-float biplane with a 200-hp Curtiss V-X-X engine that arrived at NAS Pensacola in June 1917. With the pilot sitting in the rear seat, the R-6 was of very limited usefulness. Nevertheless, one squadron became the first American Navy planes overseas when, in January 1918, they were sent to the Azores to patrol with two 50-pound bombs against submarines.
The last 40 of 158 built were fitted with Liberty engines and designated R-6L. The increased power enabled them to handle a light (1,036-pound) torpedo and tests began on May 3, 1919. Torpedo detachments were then organized at Hampton Roads and San Diego, but the R-6L was not nearly rugged enough for service conditions.
A more practical system was the torpedo-carrying version of Martin’s Army MB-l bomber. The first of ten ordered September 30, 1919, was flown February 4, 1920, called the MBT by the Navy, and had two Liberty engines between the wings. Beginning with the third example, which was first flown on April 26 and tested by the Army at McCook Field in August, they had their engines on the lower wing and were designated MT-l (would become TM-l under the system adopted in March 1923 for new aircraft).
The pilot sat ahead of the biplane wings and cockpits for the front and rear gunner were fitted with Scarff rings for Lewis guns, and the outer wings folded back for stowage. A 1,628-pound Mk 7 torpedo or a 1,000 or 1,650-pound bomb, or six 250-pound bombs were carried between the four-wheeled landing gear. Martin delivered the last from Cleveland in August 1920. Six went to NAS Hampton Roads until replaced by PT-1 seaplanes in September 1921, and then went to the Marines at Quantico, while four served NAS San Diego until also transferred to Quantico in April 1923.
Philadelphia’s Naval Aircraft Factory combined surplus R-6L fuselages, HS-1L wings, and Liberty engines, to produce 15 PT-l two-place twin-float seaplanes ordered January 1921 and delivered beginning in August. Larger HS-2 wings were used on 18 PT-2s completed by June 1922. Torpedo and Bombing Plane Squadron One conducted the first mass torpedo practice on a live target on September 27, 1922. Eighteen PTs attacked the USS Arkansas, running at full speed, and scored eight hits with their Mk 7 torpedoes. But the PTs could lift a Mk 7 torpedo only if a single pilot and no guns were carried.
During the summer of 1922, the Navy tested five prototypes competing for a torpedo-plane contract. Two were twin-engine two-place types venturing a low-wing monoplane layout new for that period. Ordered June 30, 1920, and first flown on May 2, 1921, at NAS Rockaway Beach, N.Y., the Curtiss CT-l had two 300-hp Wright-Hispano engines above twin floats, but used 350-hp Curtiss D-12s when flown to Anacostia on January 13, 1922. A short fuselage of wooden construction had the pilot ahead of a rear gunner, while tail booms extended behind to a biplane tail. A Mk 7 torpedo could be carried, but only one of nine CT-ls ordered was completed.
The Navy’s first all-metal low-wing monoplane was the Stout ST torpedo plane, a clean design with two 300-hp Packard Liberty engines, twin rudders, and wheeled landing gear. Five had been ordered from designer William B. Stout’s (1880-1956) Metal Plane company in Detroit, with the first flown April 25, 1922, but the rest were canceled when the prototype crashed after the 13th flight.
Two foreign-built single-engine designs were also studied. Three twin-float, low, cantilever-wing Fokker FT three-seaters were imported from the Netherlands, and the first was flown there on January 22, 1922, with a 400-hp Liberty engine. The first reached Anacostia June 29, along with a pair of Blackburn Swifts from Britain, biplanes with a 450-hp Napier Lion, wheels “releasable” in emergencies, flotation gear, and folding wings. These single-seat torpedo planes had the pilot sitting in a humped cockpit.