Douglas O-2

The Douglas O-2 was a 1920s American observation aircraft built by the Douglas Aircraft Company and powered by the Liberty engine of World War I fame, with some later variants using other engines. The family sprang from two XO-2 prototypes, the first of them powered by a 420 hp Liberty V-1650-1 and test-flown in the autumn of 1924. It developed into several versions, 879 were produced in total, the Chinese Air Force used it in combat in the 1930s, and it was the basis of a successful mailplane. No O-2 was known to survive until 2011, when the wreckage of an O-2H lost at Kelly Field, Texas, in 1933 was identified.