Abstract
The design of piston engines for aviation applications requires the simultaneous consideration of power density, compactness, structural reliability, fuel efficiency, operational robustness, and system complexity. This study presents the design and development of a fully mechanical modular compression-ignition engine concept intended for aviation applications, including potential integration into unmanned aerial vehicle (UAV) platforms. The proposed architecture combines a distinctive cylinder concept with a modular engine structure and a specific crankshaft configuration performing a dual functional role. The engine is conceived to perform its fundamental functions through predominantly mechanical systems, thereby reducing dependence on electronic engine-management architectures. The complete three-dimensional assembly is developed in Autodesk Inventor, where the principal components, geometric relationships, crank-slider mechanism, and functional interfaces are defined and integrated. The compression-ignition architecture is additionally considered from the perspective of prospective fuel flexibility, which may be relevant under restricted fuel availability, limited infrastructure, or demanding logistical conditions. Fuel-flexible operation is treated as a design objective rather than as a demonstrated capability at the present stage. The resulting mechanical architecture and geometric configuration establish the physical reference model for subsequent one-dimensional thermodynamic and performance assessment in AVL BOOST. The proposed methodology therefore separates mechanical concept development from functional validation, enabling the constructive contribution of the new architecture to be assessed independently before its thermodynamic behaviour is investigated.