DT-1, DT-2, DT-4, DT-6, CS-1
Donald W. Douglas (1892-1981) had developed a solid-looking two-place biplane from the Cloudster, his first airplane since he left Glenn L. Martin to become an independent producer. Three were ordered on April 14, 1921, and the first delivered as the single-seat DT-l on November 10 to NAS San Diego. The next two were DT-2 two-seaters, and the third was flown April 18, 1922, with the radiator in front of the Liberty engine, instead of at the sides. The landing gear could be either twin floats or wheels for land-based operations, and the wings could fold back.
A 1,835-pound Mk 6 torpedo, or the 1,628-pound Mk 7, was carried beneath the fuselage between the fuselage, and a Lewis gun provided for rear defense. Launching torpedoes was a delicate matter, for they were prone to fail or misdirect if the plane wasn’t flying absolutely straight or more than 32 feet high, or more than 100 mph. Actually, less than 25 feet high and 90 mph worked best.
The Navy ordered 38 more DT-2s delivered from the Douglas Santa Monica factory from October 1922 to October 1923. Another 11 were built by Dayton-Wright, 20 by LWF, and six by the NAF. DT-2s first entered service at San Diego with VT-2 in December 1922, and served with squadrons VT-1 at Hampton Roads, VT-5 at Pearl Harbor, and VT-20 at Cavite in the Philippines. Norway got one DT-2B from Douglas in 1924 and built eight more in Oslo, and four DTB models with 650-hp Wright Typhoon engines were later sold to Peru.
Post-delivery modifications of DT-2s included four NAF DT-4s of 1924 with 525-hp Wright T-2s, one becoming a DT-5 with a geared T-2, and the DT-6 flown April 27, 1925, as a test bed for the first 400-hp Wright P-l air-cooled radial. Dayton-Wright modified three LWF ships as SDW-l long-range scouts.
Curtiss won a contract to build six examples of a BuAer design for a three-place biplane capable of scouting, torpedo, or bombing missions. The first CS-l was completed in November 1923 with a 525-hp inline Wright T-2 Tornado, two cockpits behind the folding wings, and twin floats interchangeable with wheels. The upper wing was smaller in span than the lower, a reverse of usual biplane practice, and a 1,628-pound torpedo was carried under the fuselage along with a flexible Lewis for the gunner, and a radio for an operator within the fuselage.
One CS-1 became a CS-2 with a 585-hp Wright T-3 and radiators on the upper wing in January 1924, and Curtiss delivered two more CS-2s with increased fuel capacity. The last CS-1 tested the Packard engine with a three-blade propeller proposed for the future T3M-1.
The CS design was chosen to replace the DT-2s in service and contracts were let in June 1924 after open bidding in which Curtiss, asking $32,000, was underbid by Martin, asking $20,000. Thirty-five three-place Martin
SC-1s with T-2 engines, similar to the CS-1, were delivered between February and August 1925. Forty SC-2s with T-3s were ordered in January and delivered by December 1925. They equipped VS-1, VS-3, VT-1, and VT-2, and carried their Lewis gun on a ring in the center cockpit, the third crewman located behind him inside the fuselage.
Boeing received the next contract to build prototypes to a Navy design built around the 710-hp Packard 1A-2500. The pilot and torpedo-man sat side-by-side ahead of the folding wings, with a gunner in the rear, and the landing gear was convertible from twin floats to four wheels. Although three Boeing TB-1 torpedo planes were purchased in May 1925, the first was not flown until May 4, 1927.