Douglas O-2

The Douglas O-2 is a 1920s American observation aircraft built by the Douglas Aircraft Company.

Development

The important family of Douglas observation aircraft sprang from two XO-2 prototypes, the first of which was powered by the 420-hp (313-kW) Liberty V-1650-1 Vee engine and test-flown in the autumn of 1924. The second XO-2 was powered by the 510-hp (380-kW) Packard 1A-1500 Vee engine, which proved unreliable. The US Army ordered 45 0-2 production aircraft in 1925, these retaining the XO-2's welded steel tube fuselage, wooden wings and overall fabric covering but at the same time introducing aluminium panels on the forward fuselage. The XO-2 had been flown with short and long-span wings, the latter giving improved handling and therefore being specified for the production aircraft. The fixed tailskid landing gear included a main unit of the divided type, the horizontal tail surface was strut braced, and the engine was cooled by a tunnel radiator.

The 0-2 proved to be a conventional but very reliable biplane which soon attracted orders for 25 more aircraft: 18 0-2A machines equipped for night flying and six 0-2B dual-control command aircraft for the US Army, plus one civil 0-2BS modified specially for James McKee, who made a remarkable solo transCanada flight in September 1926. In 1927 the O-2BS was adapted as a threeseater with a radial engine.

Variants

0-2C: These differed from the 0-2 in having frontal radiators for their Liberty engines and modified oleo-strut landing gear. The USAAC took delivery of 19 aircraft, while the remaining 27 went to reserve National Guard units.

0-2D: Two unarmed staff transport versions of the 0-2C.

0-2E: A one-off aircraft which replaced the wire link between upper and lower wing ailerons of production aircraft by rigid struts.

0-2H: The fuselage was redesigned and a new tailplane was fitted, with staggered wings of unequal span. The O-2H incorporated the rigid-strut aileron interconnections of the 0-2E. An improved split-axle landing gear was standard. The USAAC received 90 O-2Hs between 1928 and 1930, and the National Guard a further 50.

0-2J: Three unarmed 0-2Hs for service as USAAC staff transports.

0-2K: A slightly modified version of the O2J for US Army staff transport and liaison duties. Total production was 37 for the USAAC and 20 for the National Guard.

XO-6: Five all-metal O-2s, built in the mid-1920s by Thomas-Morse.

XO-6B: Radically altered (smaller and lighter) version of the XO-6.

0-7: Three 0-2s with the 510-hp (380-kW) Packard 2A-1500 direct-drive engine. Two were later converted to 0-2 standards, and one to the O-2C standard.

0-8: One aircraft with the 400-hp (298-kW) Curtiss R-1454 radial engine instead of the intended Packard inverted-Vee engine. It later became an 0-2A.

0-9: One aircraft with the 500-hp (373-kW) Packard 3A-1500 geared engine. It resembled the 0-7 but had a four rather than two bladed propeller. It later became an O-2A.

XO-14: One reduced-scale version of an 0-2H and the first Douglas aircraft with wheel brakes.

XA-2: The 46th aircraft of the original 0-2 contract was completed as an attack machine with the powerplant of one 420-hp (313-kW) V-1410 Liberty inverted-Vee engine, and with a total of eight machine-guns (two in the engine cowling, two each in the upper and lower wings, and two on a ring-mounting operated by the observer). It was remarkably well armed for its day, and competed against the Curtiss A-3 in 1926 but was not selected for production.

OD-1: Two O-2Cs for service with the US Marine Corps from 1929.

Specifications (0-2)

General characteristics

• Crew: two

Performance Armament

• Two .30-cal (7.62 mm) Browning machine guns, one fixed forward-firing and one flexible
• 400 lbs (181 kg) of disposable stores carried under the lower wing

Reference

• The complete Encyclopedia of World Aircraft cover Editors: Paul Eden & Soph Moeng, Amber Books Ltd. Bradley's Close, 74-77 White Lion Street, London, NI 9PF, 2002, 1152 pp.