Thomas-Morse O-41

The Thomas-Morse O-41 was a version of the successful O-19 observation aircraft that was given sesquiplane wings and a Curtiss Conqueror engine, but failed in two attempts to win a USAAC contract, and was eventually sold to Republican Spain, although probably got no further than Mexico.

The O-19 was an indirect development of the Douglas O-2 observation. In 1926 Thomas-Morse had been given a contract to produce two examples of the O-2, but with the wooden wing structure replaced with an all metal one. The resulting O-6 hadn’t received an USAAC order, but Thomas-Morse decided to produce their own improved design, as the privately funded XO-6B. This had an all metal framework for the fuselage and wings and a fabric covering, and replaced the inline Liberty engine of the O-2 and O-6 with a Pratt & Whitney Wasp R-1340 radial engine. This time the USAAC was impressed, and ordered four test aircraft, the first of over 170 O-19s that would be produced.

A number of different engines were tested in the O-19 fuselage. This included the Curtiss Conqueror, which was first installed in the O-23, and then in an existing O-19B to produce the sole Y1O-33 of 1930. The Y1O-33 was also given a modified tail.

The Y1O-33 design then became the basis of the Y1O-41. This was a sequiplane, with a lower wing half the size of the upper wing, powered by a 600hp Curtiss GV-1570-29 (a geared version of the Curtiss Conqueror). The Y1O-41 made its maiden flight on 4 May 1931 and then went for tests at Wright Field in June 1931. While there it reached a top speed of 195mph, a big improvement over the 139mph of the standard O-19B. At this point it was known as the XO-932.

By this time the limits of the Conqueror engine were becoming apparent, and in 1932 the Military withdrew funding for further development of the type. Possibly as a result of this, no orders were placed for the Y1O-41. The single prototype was bought back by Curtiss, and in September 1934 rebuilt as the Model 23. This aircraft was entered into a USAAC competition for an observation aircraft, but lost out to a Douglas design.

A picture dated to 18 September 1934 shows this aircraft with an enclosed cockpit, and still with the XO-932 designation painted on the corrugated surface of the fuselage. The wheels are protected by fairings.

The Model 23 was rebuilt once again, and in August 1935 placed on the civil registry as NR33Y. Consolidated used it as a company ‘hack’, until Clint Warner helped the company sell it to Colonel Alfredo Lezama Alvarez, a representative of the Spanish Republican Government. The aircraft was moved to Mexico, where Alvarez was based, but probably never reached Spain.

Frustratingly it isn’t clear if the O-41 was a conversion of an existing O-19, the O-33 or built from scratch. It is often said to have been produced by modifying the O-33, serial number 30-90. However this aircraft is recorded as being destroyed in a crash on 9 May 1934 close to Flint, Michigan, while serving with the 57th Service Squadron. The accident report lists it as the O-33B. Several photographs exist of the O-41/ O-932, but none of them show a standard serial number. The most likely answer is that the O-41 was built from new, and didn’t receive a USAAC serial number.


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How to cite this article: Rickard, J (28 October 2019), Thomas-Morse O-41 ,

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