Design and development
One Douglas O-2, serial number 25-380, was modified for the new role as an attack aircraft. While the basic structure of the aircraft remained, there were several modifications made. The water-cooled Liberty engine (V-1650) of the O-2 was replaced by an inverted air-cooled Allison VG-1410 engine. The lower engine cowlings were omitted to allow for more cooling air flow over the engine.
Second, the XA-2 was more heavily armed than the O-2. It had six forward-firing .30-caliber Browning machine guns - two in the nose forward of the cockpit, and two each in the mid-upper and lower wings. Two .30-caliber Lewis guns were put on a flexible mount for use by the observer-gunner in rear defense of the aircraft. [1] The aircraft also had the capacity for a small bomb load of 100 lb (45 kg).
The Douglas XA-2 was evaluated against the Curtiss XA-3 (a conversion of the Curtiss O-1B observation plane). The Douglas Aircraft won the initial competition, but the Army realized that the Liberty engine was both underpowered and in dwindling supply. It ordered a second competition with both models upgraded with Packard 1A-1500 engines. The Curtiss aircraft won this time and became the U.S. Army Air Corps' frontline attack aircraft (Curtiss A-3 Attack Falcon) from 1928 to 1935.
The Curtiss A-12 Shrike was the United States Army Air Corps' second monoplane ground-attack aircraft, and its main attack aircraft through most of the 1930s. It was based on the A-8, but had a radial engine instead of the A-8's inline, water-cooled engine, as well as other changes.
The Curtiss A-8 was a low-wing monoplane ground-attack aircraft built by the United States company Curtiss Aeroplane and Motor Company, designed in response to a 1929 United States Army Air Corps requirement for an attack aircraft to replace the A-3 Falcon. The Model 59 "Shrike" was designated XA-8.
The Fokker XA-7 was a prototype attack aircraft ordered in December 1929, and first flown in January 1931 by Fokker and then General Aviation Corporation after it bought Fokker-America in 1930, and entered in a competition held by the United States Army. However, the Curtiss A-8 won the competition, and A-7 development was not continued.
The Douglas XB-42 Mixmaster was an experimental American bomber aircraft, designed for a high top speed. The unconventional approach was to mount the two engines within the fuselage driving a pair of contra-rotating propellers mounted at the tail in a pusher configuration, leaving the wing and fuselage clean and free of drag-inducing protrusions.
The Beechcraft XA-38 "Grizzly" was a World War II-era ground attack aircraft, developed by Beechcraft, but never put into production. The Grizzly was to have been fitted with a forward-firing 75 mm cannon to penetrate heavily armored targets.
The Douglas A-26 Invader is an American twin-engined light bomber and ground attack aircraft. Built by Douglas Aircraft Company during World War II, the Invader also saw service during several major Cold War conflicts. A limited number of highly modified United States Air Force aircraft served in Southeast Asia until 1969. It was a fast aircraft capable of carrying a large bomb load. A range of guns could be fitted to produce a formidable ground-attack aircraft.
The Douglas Y1B-7 was a 1930s American bomber aircraft. It was the first US monoplane given the B- 'bomber' designation. The monoplane was more practical and less expensive than the biplane, and the United States Army Air Corps chose to experiment with monoplanes for this reason. At the time the XB-7 was ordered, it was being tested by Douglas Aircraft as an observational plane.
The XB-38 Flying Fortress was a single example conversion of a production B-17E Flying Fortress, testing whether the Allison V-1710 V type engine could be substituted for the standard Wright R-1820 radial engine during early World War II.
The Lockheed XP-58 Chain Lightning was an American long-range fighter developed during World War II. Although derived from the successful P-38 Lightning, the XP-58 was plagued by technical problems with its engines that eventually led to the project's cancellation.
The Martin Model 167 Maryland was an American light bomber that first flew in 1939. It saw action in World War II with France and the United Kingdom.
The Curtiss XA-14 was a 1930s United States airplane, the first multi-engine attack aircraft tested by the United States Army Air Corps. Carrying a crew of two, it was as fast as the standard pursuit aircraft in service at the time.
The Douglas A-33 was an American attack aircraft built in small numbers during World War II. It was an updated version of the Northrop A-17, with a more powerful engine and an increased bomb load. While the A-33 was intended initially for the export market, the entire production run was taken up by the United States Army Air Corps.
The Northrop Gamma was a single-engine all-metal monoplane cargo aircraft used in the 1930s. Towards the end of its service life, it was developed into the A-17 light bomber.
The Consolidated P-30 (PB-2) was a 1930s United States two-seat fighter aircraft. An attack version called the A-11 was also built, along with 2 Y1P-25 prototypes and YP-27, Y1P-28, and XP-33 proposals. The P-30 is significant for being the first fighter in United States Army Air Corps service to have retractable landing gear, an enclosed and heated cockpit for the pilot, and an exhaust-driven turbo-supercharger for altitude operation.
The Henschel Hs 124 was Henschel's entry into the Luftwaffe's twin-engine Kampfzerstörer requirement, but was abandoned after this programme was split into separate Zerstörer and Schnellbomber requirements. Three prototypes were planned, but only two were built
The Douglas O-43 was a monoplane observation aircraft used by the United States Army Air Corps.
The Douglas O-2 was a 1920s American observation aircraft built by the Douglas Aircraft Company, powered by the Liberty engine of WW1 fame, with some later variants using other engines. It was developed into several versions, with 879 being produced in total. It was used in combat by the Chinese Air Force in the 1930s and also was the basis for a successful mailplane version.
The Breda Ba.201 was an Italian dive bomber designed during World War II, that never entered production.
The Keystone XLB-3 was a prototype bomber biplane developed in the United States in the late 1920s. It was a twin-engine development of the single-engine LB-1, brought about by a change in policy by the United States Army Air Corps (USAAC).
The Douglas XO2D-1 was a prototype American observation floatplane of the 1930s. It was a single engined biplane intended to be launched by aircraft catapult from ships of the United States Navy, but only one was built, the production contract going to Curtiss for the SOC Seagull.
