Thomas-Morse O-19 - version overview:
XO-6 - prototype all-metal version O-2, Liberty 12 engine
O-6- four machines for Army tests, Liberty V-1650-1 engine
XO-6B - O-6 modified for R-1340 radial engine, fuselage covered with corrugated sheet metal
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XO-19 - another prototype, R-1340-3 engine
O-19 - two machines for Army tests
O-19A - similar to O-19 without main fuel tank
O-19B - production version, modified cockpits
O-19C - production version, cowled engine and spur wheel instead of rail
O-19D - O-19C with winglets O-19E, the personal aircraft of the Minister of Defence
O-19E - extended wings
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YO-20 - prototype with R-1690-1 engine, second conversion from O-19
XO-21 - prototype with Curtiss H-1640 Chieftain engine, second O-21 converted from O-19
XO-21A - XO-21 with Wright R-1750-1 engine
YO-23 - prototype with Curtiss GV-1570-29 Conqueror engine
Y1O-33 - one and a half aircraft converted from the O-19B, renamed Y1O-41, rebuilt as the Consolidated 23 after rejection by the Air Force, sold to Mexico and perhaps the Spanish Republicans
Source:
Wegg, John. General Dynamics Aircraft and their Predecessors. Naval Institute Press, Annopolis 1990, ISBN 0-87021-233-8
http://airplane.designation-systems.net/AF.htm
http://www.aerofiles.com/_thomas.html
XO-6 - prototype all-metal version O-2, Liberty 12 engine
O-6- four machines for Army tests, Liberty V-1650-1 engine
XO-6B - O-6 modified for R-1340 radial engine, fuselage covered with corrugated sheet metal
______________________________________
XO-19 - another prototype, R-1340-3 engine
O-19 - two machines for Army tests
O-19A - similar to O-19 without main fuel tank
O-19B - production version, modified cockpits
O-19C - production version, cowled engine and spur wheel instead of rail
O-19D - O-19C with winglets O-19E, the personal aircraft of the Minister of Defence
O-19E - extended wings
______________________________________
YO-20 - prototype with R-1690-1 engine, second conversion from O-19
XO-21 - prototype with Curtiss H-1640 Chieftain engine, second O-21 converted from O-19
XO-21A - XO-21 with Wright R-1750-1 engine
YO-23 - prototype with Curtiss GV-1570-29 Conqueror engine
Y1O-33 - one and a half aircraft converted from the O-19B, renamed Y1O-41, rebuilt as the Consolidated 23 after rejection by the Air Force, sold to Mexico and perhaps the Spanish Republicans
Source:
Wegg, John. General Dynamics Aircraft and their Predecessors. Naval Institute Press, Annopolis 1990, ISBN 0-87021-233-8
http://airplane.designation-systems.net/AF.htm
http://www.aerofiles.com/_thomas.html