Douglas O-2
Encyclopedia
The Douglas O-2 is a 1920s American
observation aircraft built by the Douglas Aircraft Company
.
V-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 O-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 O-2 proved to be a conventional but very reliable biplane
which soon attracted orders for 25 more aircraft: 18 O-2A machines equipped for night flying and six O-2B dual-control command aircraft for the US Army, plus one civil O-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.
The O-2Hs were an entirely new design but continued the same basic model number. Major differences were heavily staggered wings, a more compact engine installation, and clean landing gear secured to the fuselage.
Up to 2011 there were no O-2's known to exist. However in 2011 the wreckage of O-2H 29-163 that crashed out of Kelly Field Texas on March 16, 1933 has been positively identified. The rear and central/forward portion of the fuselage behind the firewall, wing attachments and landing gear parts, tailplane and many engine parts and eight of the twelve pistons are now recovered. Research is continuing on this aircraft. It is known it was flown by Aviation Cadet Charles D. Rogers on a night recon advanced training mission. Apparently flying low, the aircraft hit a hill and burned after the crash leaving only the found wreckage today. Weather was not considered a contributing factor. Cadet Rogers was instantly killed in the crash by the impact. His body was recovered but the wreckage was abandoned due to the airframe and engine both being a write-off.
The only similar aircraft known to exist are a restored Douglas M-2 mailplane and a follow-on derivative of the O-25 variant, an O-38.
O-2: Initial production model - 45 built.
O-2A: O-2 with night flying equipment - 18 built.
O-2B: Dual control version of O-2 - six built.
O-2C: These differed from the O-2 in having frontal radiators for their Liberty engines
and modified oleo-strut landing gear. The USAAC took delivery of 18 aircraft, while the remaining 27 went to reserve National Guard units - 45 built and one later conversion from O-9.
O-2D: Unarmed staff transport versions of the O-2C - two built.
O-2E: A one-off aircraft which replaced the wire link between upper and lower wing ailerons of production aircraft by rigid struts.
O-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 O-2E. An improved split-axle
landing gear was standard. The USAAC received 101 O-2Hs between 1928 and 1930, and the National Guard a further 40 - 141 built.
O-2J: Unarmed dual control version of the O-2H for service as USAAC staff transports - three built.
O-2K: A slightly modified version of the O-2J for US Army staff transport and liaison
duties. 30 built for the USAAC and 20 for the National Guard - 50 built.
O-2M: various export versions of O-2 that saw services with Republic of China Air Force
. These aircraft were used as scout-bombers by the Chinese in the Second Sino-Japanese War
with somewhat limited success against Japanese ground targets. It was also used by the Mexican Air Force
with Lewis and Vickers machine guns, with very good results.
O-2MC: Export version for China, powered by a Hornet radial engine - 10 built
O-2MC-2: Export version for China, with the Hornet radial engine surrounded by a Townend ring - 20 built
O-2MC-3: Export version for China, fitted with an uprated 429-kW (575-hp) Hornet radial engine - 5 built
O-2MC-4: Export version for China - 12 built
O-2MC-5: Export version for China, fitted with the less powerful 313-kW (420-hp) Pratt & Whitney Wasp C1 engine - 12 built
O-2MC-6: Export version for China, fitted with the 429-kW (575-hp) Wright R-1820-E radial engine - 22 built
O-2MC-10: Export version for China, fitted with a 500-kW (670-hp) Wright R-1820-F21 radial engine - 1 built
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 - one built.
O-7: Three O-2s refitted with the 510-hp (380 kW) Packard 2A-1500 direct-drive engine. Two were later converted to O-2 standards, and one to the O-2C standard.
O-8: One O-2 with the 400 hp (298 kW) Curtiss R-1454 radial engine instead of the intended Packard inverted-Vee engine. It later became an O-2A.
O-9: One O-2 refitted 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 O-2H, with a 220 hp (164 kW) Wright J-5 engine, and the first Douglas aircraft with wheel brakes.
XA-2: The 46th aircraft of the original O-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.
O-22: O-2H airframe with a swept-back upper wing and a Pratt & Whitney Wasp
engine.
O-25: O-2H airframe with a Curtiss Conqueror engine, and a revised nose. Later redesignated as the XO-25A
O-25A: Forty-nine production versions of the O-25.
O-25B: Three unarmed O-25As fitted with dual controls. Used as staff transport aircraft
O-25C: 29 production O-25s with Prestone cooling system
Y1O-29: Later designated O-29A: Two O-2K airframes fitted with a Wright R-1750 Cyclone
engine.
O-32: O-2K conversion with Pratt & Whitney R-1340-3 Wasp
engine, most later fitted with anti-drag rings
.
O-32A: Production O-32, 30 built.
YO-34: O-22 re-fitted with a Curtiss Conqueror engine.
BT-1: O-2K conversion to basic trainer, 30 converted.
BT-2: O-32 airframe converted to basic trainer.
BT-2A: O-32A conversion to basic trainer, 30 converted.
BT-2B: First production model, 146 built. 58 later converted to BT-2BI instrument trainers. Two converted to BT-2BR and 15 to BT-2BG radio-controlled aerial target drones.
BT-2C: Second production model, 20 built. 13 converted to BT-2CI instrument trainers. Seven became BT-2CR drone controllers.
A-4: Seventeen BT-2BRs and BT-2BGs converted in 1940 as radio-controlled aerial target drones. These had tricycle gear (a steerable nosewheel was added) with main gear moved aft, faired-over rear cockpit, and single controls, allowing the aircraft to be test-flown.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
observation aircraft built by the Douglas Aircraft Company
Douglas Aircraft Company
The Douglas Aircraft Company was an American aerospace manufacturer, based in Long Beach, California. It was founded in 1921 by Donald Wills Douglas, Sr. and later merged with McDonnell Aircraft in 1967 to form McDonnell Douglas...
.
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-1650-1Liberty L-12
The Liberty L-12 was a 27 litre water-cooled 45° V-12 aircraft engine of 400 horsepower designed both for a high power-to-weight ratio and for ease of mass production.-History:...
V-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 O-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
Radiator
Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles, buildings, and electronics...
.
The O-2 proved to be a conventional but very reliable biplane
Biplane
A biplane is a fixed-wing aircraft with two superimposed main wings. The Wright brothers' Wright Flyer used a biplane design, as did most aircraft in the early years of aviation. While a biplane wing structure has a structural advantage, it produces more drag than a similar monoplane wing...
which soon attracted orders for 25 more aircraft: 18 O-2A machines equipped for night flying and six O-2B dual-control command aircraft for the US Army, plus one civil O-2BS modified specially for James McKee
Trans-Canada Trophy
The Trans-Canada Trophy, also known as the McKee Trophy, is awarded by the Canadian Aeronautics and Space Institute to a Canadian citizen who has made an outstanding, contemporary achievement in aerospace operations, whether a single act within the year prior to the award or a sustained level of...
, who made a remarkable solo transCanada flight in September 1926. In 1927 the O-2BS was adapted as a threeseater with a radial engine.
The O-2Hs were an entirely new design but continued the same basic model number. Major differences were heavily staggered wings, a more compact engine installation, and clean landing gear secured to the fuselage.
Up to 2011 there were no O-2's known to exist. However in 2011 the wreckage of O-2H 29-163 that crashed out of Kelly Field Texas on March 16, 1933 has been positively identified. The rear and central/forward portion of the fuselage behind the firewall, wing attachments and landing gear parts, tailplane and many engine parts and eight of the twelve pistons are now recovered. Research is continuing on this aircraft. It is known it was flown by Aviation Cadet Charles D. Rogers on a night recon advanced training mission. Apparently flying low, the aircraft hit a hill and burned after the crash leaving only the found wreckage today. Weather was not considered a contributing factor. Cadet Rogers was instantly killed in the crash by the impact. His body was recovered but the wreckage was abandoned due to the airframe and engine both being a write-off.
The only similar aircraft known to exist are a restored Douglas M-2 mailplane and a follow-on derivative of the O-25 variant, an O-38.
Variants
XO-2: Two pre-production prototypes.O-2: Initial production model - 45 built.
O-2A: O-2 with night flying equipment - 18 built.
O-2B: Dual control version of O-2 - six built.
O-2C: These differed from the O-2 in having frontal radiators for their Liberty engines
Liberty L-12
The Liberty L-12 was a 27 litre water-cooled 45° V-12 aircraft engine of 400 horsepower designed both for a high power-to-weight ratio and for ease of mass production.-History:...
and modified oleo-strut landing gear. The USAAC took delivery of 18 aircraft, while the remaining 27 went to reserve National Guard units - 45 built and one later conversion from O-9.
O-2D: Unarmed staff transport versions of the O-2C - two built.
O-2E: A one-off aircraft which replaced the wire link between upper and lower wing ailerons of production aircraft by rigid struts.
O-2H: The fuselage was redesigned and a new tailplane was fitted, with staggered wings of unequal span. The O-2H incorporated the rigid-strut
Strut
A strut is a structural component designed to resist longitudinal compression. Struts provide outwards-facing support in their lengthwise direction, which can be used to keep two other components separate, performing the opposite function of a tie...
aileron interconnections of the O-2E. An improved split-axle
Axle
An axle is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to its surroundings, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle...
landing gear was standard. The USAAC received 101 O-2Hs between 1928 and 1930, and the National Guard a further 40 - 141 built.
O-2J: Unarmed dual control version of the O-2H for service as USAAC staff transports - three built.
O-2K: A slightly modified version of the O-2J for US Army staff transport and liaison
Liaison aircraft
A liaison aircraft is a small, usually unarmed aircraft primarily used by military forces for artillery observation or transporting commanders and messages. The concept developed before World War II and included also battlefield reconnaissance, air ambulance, column control, light cargo delivery...
duties. 30 built for the USAAC and 20 for the National Guard - 50 built.
O-2M: various export versions of O-2 that saw services with Republic of China Air Force
Republic of China Air Force
The Republic of China Air Force is the aviation branch of the Republic of China Armed Forces. The ROCAF's primary mission is the defense of the airspace over and around Taiwan...
. These aircraft were used as scout-bombers by the Chinese in the Second Sino-Japanese War
Second Sino-Japanese War
The Second Sino-Japanese War was a military conflict fought primarily between the Republic of China and the Empire of Japan. From 1937 to 1941, China fought Japan with some economic help from Germany , the Soviet Union and the United States...
with somewhat limited success against Japanese ground targets. It was also used by the Mexican Air Force
Mexican Air Force
The Mexican Air Force is the aviation branch of the Mexican Army and depends on the National Defense Secretariat . Since 2008, its commander is Gen...
with Lewis and Vickers machine guns, with very good results.
O-2MC: Export version for China, powered by a Hornet radial engine - 10 built
O-2MC-2: Export version for China, with the Hornet radial engine surrounded by a Townend ring - 20 built
O-2MC-3: Export version for China, fitted with an uprated 429-kW (575-hp) Hornet radial engine - 5 built
O-2MC-4: Export version for China - 12 built
O-2MC-5: Export version for China, fitted with the less powerful 313-kW (420-hp) Pratt & Whitney Wasp C1 engine - 12 built
O-2MC-6: Export version for China, fitted with the 429-kW (575-hp) Wright R-1820-E radial engine - 22 built
O-2MC-10: Export version for China, fitted with a 500-kW (670-hp) Wright R-1820-F21 radial engine - 1 built
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 - one built.
O-7: Three O-2s refitted with the 510-hp (380 kW) Packard 2A-1500 direct-drive engine. Two were later converted to O-2 standards, and one to the O-2C standard.
O-8: One O-2 with the 400 hp (298 kW) Curtiss R-1454 radial engine instead of the intended Packard inverted-Vee engine. It later became an O-2A.
O-9: One O-2 refitted 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 O-2H, with a 220 hp (164 kW) Wright J-5 engine, and the first Douglas aircraft with wheel brakes.
XA-2: The 46th aircraft of the original O-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
Curtiss Falcon
The Curtiss Falcon is a family of military biplane aircraft built by the United States aircraft manufacturer Curtiss Aeroplane and Motor Company during the 1920s. Most saw service as part of the United States Army Air Corps as observation aircraft with the designations O-1 and O-11, or as the...
in 1926 but was not selected for production.
OD-1: Two O-2Cs for service with the US Marine Corps from 1929.
O-22: O-2H airframe with a swept-back upper wing and a Pratt & Whitney Wasp
Pratt & Whitney Wasp
-External links:*...
engine.
O-25: O-2H airframe with a Curtiss Conqueror engine, and a revised nose. Later redesignated as the XO-25A
O-25A: Forty-nine production versions of the O-25.
O-25B: Three unarmed O-25As fitted with dual controls. Used as staff transport aircraft
O-25C: 29 production O-25s with Prestone cooling system
Y1O-29: Later designated O-29A: Two O-2K airframes fitted with a Wright R-1750 Cyclone
Wright Cyclone
Wright Cyclone was the name given to a family of air-cooled radial piston engines designed by Curtiss-Wright and used in numerous American aircraft in the 1930s and 1940s.-Background:...
engine.
O-32: O-2K conversion with Pratt & Whitney R-1340-3 Wasp
Pratt & Whitney R-1340
|-See also:* Pratt & Whitney Wasp series* Pratt & Whitney R-985 Wasp Junior* Pratt & Whitney R-1535 Twin Wasp Junior* Pratt & Whitney R-1830 Twin Wasp-Bibliography:...
engine, most later fitted with anti-drag rings
Townend ring
A Townend Ring is a narrow-chord cowling ring fitted around the cylinders of an aircraft radial engine to reduce drag and improve cooling.-Development:...
.
O-32A: Production O-32, 30 built.
YO-34: O-22 re-fitted with a Curtiss Conqueror engine.
BT-1: O-2K conversion to basic trainer, 30 converted.
BT-2: O-32 airframe converted to basic trainer.
BT-2A: O-32A conversion to basic trainer, 30 converted.
BT-2B: First production model, 146 built. 58 later converted to BT-2BI instrument trainers. Two converted to BT-2BR and 15 to BT-2BG radio-controlled aerial target drones.
BT-2C: Second production model, 20 built. 13 converted to BT-2CI instrument trainers. Seven became BT-2CR drone controllers.
A-4: Seventeen BT-2BRs and BT-2BGs converted in 1940 as radio-controlled aerial target drones. These had tricycle gear (a steerable nosewheel was added) with main gear moved aft, faired-over rear cockpit, and single controls, allowing the aircraft to be test-flown.
Operators
- Republic of China Air ForceRepublic of China Air ForceThe Republic of China Air Force is the aviation branch of the Republic of China Armed Forces. The ROCAF's primary mission is the defense of the airspace over and around Taiwan...
- Mexican Air ForceMexican Air ForceThe Mexican Air Force is the aviation branch of the Mexican Army and depends on the National Defense Secretariat . Since 2008, its commander is Gen...
- United States Army Air CorpsUnited States Army Air CorpsThe United States Army Air Corps was a forerunner of the United States Air Force. Renamed from the Air Service on 2 July 1926, it was part of the United States Army and the predecessor of the United States Army Air Forces , established in 1941...
- United States Marine CorpsUnited States Marine CorpsThe United States Marine Corps is a branch of the United States Armed Forces responsible for providing power projection from the sea, using the mobility of the United States Navy to deliver combined-arms task forces rapidly. It is one of seven uniformed services of the United States...