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The Thomas Morse O-6 was an all-metal version of the Douglas O-2, one of the main American observation aircraft of the mid 1920s.
The O-2 was a fairly typical aircraft of its time with a welded steel tube fuselage, wooden wings and a fabric covering. It had 39ft 8in long equal span biplane wings, was powered by the inline V-12 Liberty engine and carried a crew of two. It was ordered into production in February 1925, and the first production aircraft were delivered later in the same year.
Soon after this the USAAC decided to test out a version with an all metal structure. On 21 April 1926 Thomas-Morse received an order to built two prototypes, as the XO-6.
The first aircraft, XO-6, serial number 25-435, had a metal framework for the fuselage and wings. The wings were covered with duralumin on their upper surfaces and fabric on the lower surface. It was powered by a 400hp Liberty 12 engine. The XO-6 went to McCook Field, where it was tested in May 1926. It was a fairly dated looking aircraft, with the Liberty engine contained within a rather rectangular cover and a rectangular vertical tail.
The second aircraft, O-6, serial number 25-436, was powered by a 435hp Liberty V-1650-1 engine. It was also tested at McCook, before going to Galveston, Texas, where it was left in an open hanger to test the impact of the salt in sea air on duralumin.
Three more standard O-6s were built (25-437 to 25-439), but Thomas Morse reportedly lost $60,000 on this contract.
Despite these losses, the company decided to produce their own privately funded prototype of an observation aircraft designed from the start around an all metal structure. The result was the XO-6B, which was given the USAAC serial number 25-440. This aircraft was powered by a Pratt & Whitney Wasp R-1340 radial engine, was smaller than the O-2/ O-6, had entirely fabric covered wings and a corrugated metal cover for the fuselage. The Wasp’s cylinder heads were exposed to aid cooling, and the aircraft was given a revised vertical tail, with a tapering leading edge. It carried a crew of two in separate cockpits. The pilot’s cockpit was just behind the trailing edge of the wing, and had a small windscreen. The observer’s cockpit was armed with a single machine gun on a ring mount.
This aircraft was tested by the USAAC, and was considered to be impressive enough to deserve further work. Four further prototypes were ordered, but with a new designations as the XO-19. This aircraft was ordered in sizable numbers, but most were produced after Thomas Morse had been taken over by Consolidated.