Reverse engineering of passenger jets to obtain classified design parameters

Abstract

Background – Black-box reverse engineering: Reconstruct what the aircraft does. White-box reverse engineering: Reconstruct how the aircraft was designed to do it. This poster shows white-box reverse engineering. It seeks to reconstruct underlying design variables, engineering models, constraints, and design decisions. It does not imply disassembly of a real aircraft. The theoretical reverse engineering is entirely based on external geometry, published data, engineering knowledge, and analytical / computational aircraft design methods. An alternative name: Aircraft Design Reverse Engineering. --- Purpose – Explain how classified design parameters of existing passenger jets can be determined. The classified design parameters are maximum lift coefficient for landing and take-off, the maximum aerodynamic efficiency (glide ratio, E_max) and the specific fuel consumption (SFC). --- Methodology – The concept is based on preliminary sizing of jet powered civil airplanes as taught by Scholz (2015). Preliminary sizing and reverse engineering are combined aiming for the classified design parameters as output. Equations are derived to calculate the maximum lift coefficients, the maximum aerodynamic efficiency and the specific fuel consumption. Only aircraft specifications are used, made public by the manufacturer. The calculations are quite complex with mutual relations, requiring iterative processes and optimization. Therefore, it becomes necessary to integrate everything into a tool. The tool is built in Microsoft Excel and called "Passenger Jet Reverse Engineering" (PJRE). The tool verifies the results by estimating the classified parameters with handbook methods. The tool is explained in detail in the theses. Operating instructions are given. --- Findings – Initially, the reverse engineering method of passenger jets was executed successfully for miscellaneous airplanes: Caravelle 10B (Sud-Aviation), Boeing 707-320C, BAe 146-200 (British Aerospace), A320-200 (Airbus), "The Rebel"(based on A320), Boeing SUGAR High, Boeing 747-400, Blended Wing Body VELA 2 (VELA) and Dassault Falcon 8X. Later a pairwise comparison was done of the A340-300 and IL-96-300, Boeing 727-200 Advanced and TU-154M, Fokker 100 and MD-82, A319-100 and An-72. Generally, there is good agreement between the reverse engineered values and those from verification. Only the maximum glide ratio in cruise flight, calculated from verification, is often significantly higher than calculated from reverse engineering. Specific fuel consumption in cruise flight has decreased considerably over decades of aircraft development. --- Practical Implications – Due to competition among aircraft manufacturers, many aircraft parameters cannot be made publicly available. The application of PJRE demonstrates how these parameters can nevertheless be approximated. --- Social Implications – A detailed discussion about flight costs, ticket prices, and environmental impact of air travel requires detailed knowledge of aircraft. Reverse engineering allows consumers to engage in this discussion with the industry on equal footing. --- Originality – The method was first published by De Grave (2017) and applied by Cheema (2019) supervision was by Scholz. This is the first presentation at a conference.