The Thomas-Morse O-19 was a two-man observation biplane loosely based on the Douglas O-2, but with an all metal structure. 171 production aircraft were ordered, and it became one of the standard US observation types at the start of the 1930s.
The Douglas O-2 had been ordered into production in February 1925. The fuselage was built around a welded steel tube structure, while the wings had a wooden structure. It was entirely fabric covered. On 21 April 1926 Thomas-Morse was given a contract to produce two examples of the O-2 but with an all metal structure, as the O-6. Two prototypes and three production aircraft were built. The first prototype, the XO-6, had a metal framework for the fuselage and wings, and a duralumin cover on top of the wings and fabric underneath. It was tested at McCook in May 1926. The second prototype was similar, and was used to test the effects of salt air on the duralumin skin.
No further orders for the O-6 followed, but Thomas Morse thought there was still plenty of potential in the basic idea. The company produced a privately funded prototype of a similar aircraft produced from the start around an all metal structure, as the XO-6B (later given the USAAC serial number 25-440). This aircraft was smaller than the O-2, with different wing braces, an all metal framework, fabric covered wings and a corrugated metal cover for the fuselage. It was powered by the Pratt & Whitney R-1340 radial.
The XO-6B impressed the USAAC enough for them to place an order for four further aircraft on 16 June 1928, this time with the new designation of O-19.
The first XO-19 prototype (28-400) was powered by a 450hp Wasp R-1340-3 engine. It made its maiden flight in April 1929.
It was followed by two service test O-19s (28-401 and 29-369), which were powered by 500hp Wasp R-1340-9, and one O-19A (29-370), which eliminated the main 88 gallon fuel tank.
On 16 August 1929 Thomas-Morse was given a contract to produce seventy O-19Bs. This was followed by an order for seventy one O-19Cs in June 1930 and thirty O-19Es in February 1931.
The O-19 was a single bay biplane. The lower wing was attached to the base of the fuselage, the upper wing supported on struts. It had a solid fixed divided undercarriage. The fuselage and wings both had an all metal framework, with a fabric covering apart from the control surfaces, which were aluminium covered.
The O-19 was one of four ‘standard’ observation aircraft at the start of the 1930s (O-19, O-25, O-38 and O-39). It was used to equip four squadrons in the United States and four observation units in the Philippines, Panama Canal Zone and Hawaii.
In 1934 three O-19s were allocated to take part in the spring cavalry manoeuvres at Fort Riley, but the amount of time they could spend in the air during the exercises was limited, as it had to come from their normal limited allocation of flying hours!
By September 1939 the O-19 was still in service in the Philippines, with the O-19C and O-19E both still in use, alongside the O-46A.
Timeline of O-19 family
16 June 1928: Four O-19s ordered
3 November 1928: Order placed for Conqueror powered YO-23
20 December 1928: Order placed for Hornet powered O-20 and Chieftain powered O-21
April 1929: XO-19 prototypes makes maiden flight
16 August 1929: Order placed for seventy production O-19Bs
September 1929: YO-23 tested at McCook
12 June 1930: Order placed for seventy one production O-19Cs
August 1930: Y1O-33 converted from O-19B
February 1931: Order placed for thirty O-19Es.
4 May 1931: Maiden flight of sesquiplane Y1O-41
December 1936: Y1O-41 (as Model 23) sold to Col Alfredo Lezarna Alvarez in Mexico
The O-19B was powered by the 450hp Wasp R-1340-7. It had an 80 US gallon main fuel tank, was armed with two 0.3in machine guns and carried a crew of two in a new cockpit. It had an all metal fuselage and wing structure and was fabric covered apart from the control surfaces, which were aluminium covered. Seventy were ordered on 16 August 1929, but soon afterwards Thomas-Morse was taken over by Consolidated, and the aircraft were built at Buffalo, starting in March 1930.
The O-19C had a ring cowling around the engine, surrounding the exposed cylinder heads of the Wasp engine, and a tail wheel. Seventy one were ordered on 12 June 1930.
One O-19D was produced by giving an O-19C the wings and engines from the O-19E and dual controls. It was used as a staff transport for the Secretary of War.
The O-19E was powered by the 575hp Wasp R-1340-15 engine and had longer span upper wings. Thirty were ordered in February 1931.
The single O-20 combined the basic O-19 fuselage with a 525hp Pratt & Whitney Hornet Engine.
The single O-21 combined the O-19 fuselage with a 600hp Curtiss Chieftain H-1640-1. It then became the XO-21A when given a Wright Cyclone engine.
The YO-23 was powered by a 600hp Curtiss Conqueror V-1570-1 engine.
The Y1O-33 was a O-19B that was modified to use a Conqueror V-1570-11 engine and given a revised tail.
The Y1O-41 was a sesquiplane version of the O-19, tested in 1931.
Engine: One Pratt & Whitney Wasp R-1340-7 nine cylinder air cooled radial engine
Span: 39ft 9in
Length: 28ft 4in
Empty weight: 2,722lb
Gross weight: 3,800lb
Maximum take-off weight:
Max speed: 139mph at sea level
Cruising speed: 121mph
Climb Rate: 1,200ft/ min; 11min to 10,000ft
Service ceiling: 20,500ft
Range: 462 miles