This OS .25 LA engine powered my Great Planes 20 J-3 Piper Cub.
Articles About Engines and Motors for Model Airplanes, Boats, and Cars:
November & December 1962 American Modeler
November & December 1959 American Modeler
September/October 1963 American Modeler
Academy of Model Aeronautics
Tower Hobbies
Horizon Hobby
Sig Mfg
Brodak Mfg