Scope and Contents Document Type: Publication (Historical Study). Purpose: Scholarly reference. Authority: Author Expertise. Document Number: Smithsonian Annals of Flight, Vol 1, #7.Scope (from the introduction): "The D-12 engine is an excellent example of a first-line design in the history of aero engine development. It was the result not only of brilliant inspiration but of patient application, perseverance, and hard work on the part of its developers. To understand the origins of the D-12 it is...