The Baby Cyclone spark ignition engine of .359 cuin. (5.88 cc) displacement was the first commercial model engine to be designed by the legendary Bill Atwood, in collaboration with Mel Anderson. A pre-production example powered Bill’s 1935 California State Championship-winning model, impressing aircraft industry entrepreneur Major C. C. Moseley enough to buy the design and hire Bill to bring it into production at Moseley’s “Aircraft Industries Corporation” plant which was located at Grand Central Terminal in Glendale, California.

The most original feature of the Baby Cyclone was its crankshaft front rotary valve (FRV) induction, at a time when side-port induction was very much the standard. The first examples reached the market by Christmas 1935 at a time when the available model aero engine options were still very few. The engine was an immediate commercial success, with almost 20,000 examples being produced and sold over the next four years. Production (or supply) stretched into 1940, going through a series of variants from the original X through the A to F models.

The merits of the Baby Cyclone were such that it became the first model engine design to be widely copied (or cloned) by model engine designers around the modelling world.