E T Westbury designed the gasoline model airplane engine "Kestrel"  (small eagle) and published the construction article in Model Engineer magazine.  it is a rather robust model aircraft engine and follows a design that is light in weight and easy to build.  a good beginner engine and will power a good size airplane.  As usual, castings are not readily available but relax, there are only 3 castings required and the patterns would be easy to make from the drawings provided, and being aluminum the castings would make a good beginner foundry project as well!