Underneath the curvaceous bodywork, the chassis was a riveted, aluminium monocoque, with steel bulkheads onto which the suspension components were mounted.
No plywood-skin fuselage is truly monocoque, since stiffening elements are incorporated into the structure to carry concentrated loads that would otherwise buckle the thin skin.
The monocoque body integrated a steel safety cage that surrounded the passenger compartment, with collapsable engine and trunk sections for added passenger protection.