The National Airplane and Motor Company of Billings, Montana purchased the design rights for the Morehouse O-80, later the Wright-Morehouse WM-80 and then Lincoln Rocket, engine in about 1934 (PMHAA3). The National engine described below is likely a development of the WM-80 (O-80) with an increased bore. This National engine powered the National Bluebird C-3 (LP-1) aircraft, which was certified as Group 2-465 in 1934 (J9). The engine itself was not certified, but was tested and received the unapproved Engine Specification Calibration Rating No. 4-8 by the Department of Commerce (Ae39).
O-91 -- {4.0 / 3.625 / 91.1} / {101.6 / 92.1 / 1493}
2cyl; National 35; 30hp@2150rpm, 35@2400, 37@2600; 1934-36; Wt = 105#; TC = none.
Single-ignition engine.
Ae39; Aerofiles.com; J9; PMHAA3.
Applications: (US) National Bluebird C-3 (LP-1) [15506].