Thomas Morse Observation Aircraft
Observation Biplanes, 1928-1931
In April 1928, a Consolidated PT-3 trainer using the same engine was tested with observation equipment as the XO-17, and it was decided the most economical way of meeting the requirement was by use of standard primary trainers. Twenty-nine O-17s were purchased for the National Guard in 1928, along with one O-17A (R-790-3 engine), ending any need for the XO-14/15 types.
Thomas-Morse received a contract for four all-metal, air-cooled observation biplanes on June 16, 1928, with two more added on December 20. They were constructed of riveted dural tubing with corrugated dural covering the fuselage and control surfaces. The fabric-covered wings had the Clark Y airfoil.
The first prototype was the XO-19 of April 1929, with an R-1340-3 Wasp, fixed Browning gun, and a Lewis gun on the observer’s ring, while the R-1340-9 was used on the O-19. Next was the YO-20 in September 1929 with an R-1690-1 Hornet, and the fourth prototype became the XO-21 with a Curtiss H-1690-1, which later changed to the XO-21A with a Wright R-1750. A second prototype contract produced another Wasp-powered O-19 and an O-19A with a smaller, 88-gallon, fuel tank.
Thomas-Morse also produced a prototype with a water-cooled V-1570-1 Conqueror engine. The YO-23 or dered November 3, 1928, was tested September 18, 1929, but lost out to the Douglas O-25 as the Army’s Conqueror-powered two-seater.
Another company tried to compete with the O-19 as the Wasp-powered observation type. Chance Vought’s O-28 was an Army version of the Navy’s O2U-3. Purchased May 5, 1928, off the Vought production line, the O-28 had an R-1340 Wasp C rated at 450 hp, but actually yielding 625 hp. The Air Corps choice, however, was the Thomas-Morse design.
Seventy O-19B aircraft were ordered August 16, 1929, a few days after the Thomas-Morse Company had been sold to Consolidated Aircraft. A new assembly line in Buffalo delivered the O-19Bs from March to June 1930. Armed with one Browning fixed and one Browning flexible gun with 900 .30-caliber rounds, the O-19B could carry a 40-gallon drop tank or two 116-pound bombs under the fuselage. The useful load could include a 102-pound radio, 96-pound camera, or add 63 pounds for a pair of night landing lights under the wings.
Seventy-one O-19Cs ordered June 12, 1930, began appearing in November 1930 with ring cowls and tail wheels. The O-19D was a C converted to transport service while a new R-1340-15, supercharged to 5,000 feet, powered 30 O-19Es ordered February 21, 1931, and delivered beginning in September. They became the last aircraft built by Thomas-Morse, whose few assets merged with Consolidated.
The O-19 series totaled 177 aircraft and served with eight of the 13 Army observation squadrons in 1931. These included all four overseas units (the 2nd in the Philippines, 4th and 50th in Hawaii, and the 7th in the Canal Zone) as well as the 12th, 15th, 22nd and 88th in the United States. They also served to demonstrate the suitability of all-metal construction for Army aircraft.
Thomas-Morse had been less successful in adapting their aircraft to the more powerful Curtiss Conqueror engine with Prestone cooling. A geared V-1570-11 was installed in the first O-19B, rebuilt and flown on April 23, 1930, as the YlO-33, but the Douglas O-25C and Curtiss
O-39 got the Air Corps contracts for observation types with this engine.