The Mono-Spar light airplane (British) : a twin-engined low-wing cabin monoplane
This is a 1931 aeronautical technical report, an Aircraft Circular from the British Air Ministry-style series by NASA's Technical Reports Server, describing the Mono-Spar light airplane for engineers and aircraft builders. Its pictures are line drawings of structural details: exploded and cutaway views of truss frames, wing spar joints, and aileron control linkages, drawn with clean hatching and lettered keys that a designer could use as a model for diagrammatic technical illustration.
