Preliminary sizing and optimization of propeller aircraft (Part 23)

Abstract

Purpose – Preliminary sizing and optimization of propeller aircraft certified under EASA CS-23 Amendment 6 or FAA FAR Part 23. Considering relevant certification constraints and typical propulsion concepts for small aircraft. Integration of the method into a user interface known already from other tools being part of Simple Aircraft Sizing and Optimization (SAS) and PreSTo-Classic at HAW Hamburg. --- Methodology – The tool uses the proven methodology based on the Matching Chart (power-to-mass versus wing loading), the Excel-Solver and Differential Evolution (DE). Conventional propulsion: Piston engines (Otto, Otto with Turbo Compressor, Diesel) and Turboprop engines are considered. Altitude-dependent power modelling for all engines, and extended propeller efficiency calculations for variable-pitch and fixed-pitch propellers are used. The resulting tool is evaluated with the redesign of a Cessna 172. --- Findings – The new optimization tool is "SAS-Part23-Prop". The existing SAS and PreSTo Excel environment known from FAA FAR Part 25 was adapted to ensure continuous user experience. The new tool reproduces the selected Cessna 172 reference parameters almost exactly. The redesign shows that consistent assumptions for propeller efficiency, rotational speed, field-length requirements, and validated statistical parameters are essential for obtaining plausible sizing results. In addition, a simple sizing tool "PreSTo-Classic-Part23-Prop" for use in the Aircraft Design lectures is available. --- Research Limitations – The results are limited by the simplified equations and statistical parameters used in preliminary sizing. Electric propulsion concepts are not yet included. The tool is intended for conceptual design and cannot replace detailed analysis in later design phases. --- Practical Implications – The tool provides a structured environment for students and designers to evaluate CS-23 propeller aircraft concepts, compare manual and solver-based sizing workflows, and investigate the influence of engine and propeller concepts together with matching power-to-mass and wing loading. Highly automated aircraft preliminary sizing and optimization for new and redesign is possible (SAS-Part23-Prop). Alternatively, a simple tool for hand calculations is offered (PreSTo-Classic-Part23-Prop). The tools are designed to give users a steep learning curve. --- Originality – A didactically enhanced design, redesign, and optimization tool (on preliminary sizing level) for small propeller driven aircraft is made openly available. It is especially suited for students and fills a perceived gap.