Cyclomotor engines were built by the Cycloplane Company, Ltd. of Los Angeles, California. The firm was founded during the depression (c.1930) by aircraft designer Omer L. Woodson and test-pilot H. S. (Dick) Myrhes, both experienced men who had been most recently with the Simplex Aircraft Corporation of Defiance, Ohio. The Cycloplane Co. objective was to develop a low-cost training system for pilots of small lightplanes (of the size and power of present-day ultralights). The Cycloplane philosophy was similar to the WW I "Penguin" trainer concept used by the French and the US. Initial Cycloplane training was carried out with dual instruction in a two-seater that could lift off the ground only for short straight-line hops to give the student a feeling for the control response. The next step had the student practice solo in a version that could not leave the ground because it was underpowered with a very small wing, but could bank and turn with respect to its landing gear as illustrated by Juptner (J5, JTHT). Once the student had grasped the ideas of the three-axis controls from the dual instruction and from this "grass-cutter", he would proceed to solo in the Cycloplane which was a certificated (TC = 445 on 8/25/31) light aircraft. The Cyclomotor engine for the Cycloplanes was a two-stroke, two-cylinder HOAE with a two-throw crankshaft. All bearings supporting the crankshaft were of the ball or roller type. Some sources say it is the same basic engine design as the Cleone Motor Company engines. However, the specifications (Ae39) indicate that the bore is in-between those published (Ae39) for the Cleone D-25 and E-30 engines. Moreover, the crankshaft and its bearings differ basically from those of the Cleone engines. Thus, the relationships among the Cleone and Cyclomotor engines remain uncertain.
O-72 (2-Stroke) -- {3.625 / 3.5 / 72.2} / {92.1 / 88.9 / 1184}
2cyl; Cyclomotor A-2-25; 22.5hp@2350rpm; 1931-32; Wt = 55#; TC = none, but Calibrated Rating No. 4-2 was obtained on 5/28/31.
Single-ignition engine with two-throw crankshaft. There is a photo on Joe Gertler's Website and an example is in the Seattle Museum of Flight.
aerofiles.com; Ae39; J5 (for C-1, C-2), J9 (for B-1 under ATC #2-409), JTHT.
Applications: (US) Champion B-1 [12261, 14989]; Cycloplane C-1, C-2; Mendenhall M-1 Special pusher [16097].