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Received wisdom is that in this age of digital engineering, wind tunnels are in decline. The imminent demise of the wind tunnel has been eagerly anticipated for over 50 years now ... and yet they have stubbornly refused to die. Indeed, the last 10 years have seen high-speed wind tunnels stage a remarkable comeback; new tunnels are being built, existing tunnels are being upgraded, and mothballed tunnels are being reactivated. This presentation has a focus on industrial-scale transonic wind tunnels, reviews the historical development of these facilities and then looks at their current and near-future status., Hamburg Aerospace Lecture Series --- Collection of Presentations --- http://www.AeroLectures.de

Purpose – Test the aerodynamic analysis code VSPAERO, which is part of OpenVSP from NASA. Apply VSPAERO to calculate the lift curve slope and the span efficiency factor of straight wings (for various aspect and taper ratios) as well as the induced drag of box wings (for various h/b-ratios) relative to their reference wing. --- Methodology – VSPAERO results are compared with results from analytical equations, wind tunnel measurements, and results produced with other aerodynamic codes. --- Findings – VSPAERO offers correct and reliable results, if the simulation is set up with care. The user must always keep an eye on model discretization and refinement, flow conditions, and number of iterations. The Vortex Lattice Method (VLM) and the panel method are best used for different purposes. The VLM shows shorter simulation time and produces reliable results. The panel method is more complicated to use. Numerical results are also good. In addition, the panel method can be used better to visualize flow phenomena. Hoerner's simple approach to induced drag estimation can be used to approximate results of the VLM and the panel method, if a simple correction factor is applied. --- Research Limitations – Most of the tests of VSPAERO have been done with a simple wing geometry, as such much simpler than a full aircraft geometry. --- Practical Implications – VSPAERO can be used with relative ease. It can also be used to show flow phenomena on full aircraft geometry. --- Originality – Repeating simple calculations done many times before does not sound original, but doing this with the relatively new software VSPAERO offering the VLM as well as the panel method seems to be original after all.

Purpose – Find optimal flight and design parameters for three objectives: minimum fuel consumption, Direct Operating Costs (DOC), and environmental impact of a passenger jet aircraft. --- Approach – Combining multiple models (this includes aerodynamics, specific fuel consumption, DOC, and equivalent CO2 mass) into one generic model. In this combined model, each objective's importance is determined by a weighting factor. Additionally, the possibility of further optimizing this model by altering an aircraft's wing loading is analyzed. --- Findings – When optimizing for a compromise between economic and ecologic benefits, the general outcome is a reduction in cruise altitude and an unaltered cruise Mach number compared to common practice. Decreasing cruise speed would benefit the environmental impact but has a negative effect on seat-mile cost. An increase in wing loading could further optimize the general outcome. Albeit at the cost of a greater required landing distance, therefore limiting the operational opportunities of this aircraft. --- Research limitations – Most models use estimating equations based on first principles and statistical data. --- Practical implications – The optimal cruise altitude and speed for a specific objective can be approximated for any passenger jet aircraft. --- Social implications – By using a simple approach, the discussion of optimizing aircraft opens up to a level where everyone can participate. --- Value – To find a general answer on how to optimize aviation, operational and design-wise, by using a simple approach., https://dlrk2020.dglr.de

Purpose – Find optimal flight and design parameters for three objectives: minimum fuel consumption, Direct Operating Costs (DOC), and environmental impact of a passenger jet aircraft. --- Approach – Combining multiple models (this includes aerodynamics, specific fuel consumption, DOC, and equivalent CO2 mass) into one generic model. In this combined model, each objective's importance is determined by a weighting factor. Additionally, the possibility of further optimizing this model by altering an aircraft's wing loading is analyzed. --- Findings – When optimizing for a compromise between economic and ecologic benefits, the general outcome is a reduction in cruise altitude and an unaltered cruise Mach number compared to common practice. Decreasing cruise speed would benefit the environmental impact but has a negative effect on seat-mile cost. An increase in wing loading could further optimize the general outcome. Albeit at the cost of a greater required landing distance, therefore limiting the operational opportunities of this aircraft. --- Research limitations – Most models use estimating equations based on first principles and statistical data. --- Practical implications – The optimal cruise altitude and speed for a specific objective can be approximated for any passenger jet aircraft. --- Social implications – By using a simple approach, the discussion of optimizing aircraft opens up to a level where everyone can participate. --- Value – To find a general answer on how to optimize aviation, operational and design-wise, by using a simple approach.

This project evaluates the suitability and practicality of the program Athena Vortex Lattice (AVL) by Mark Drela. A short user guide was written to make it easier (especially for students) to get started with the program AVL. AVL was applied to calculate the induced drag and the Oswald factor. In a first task, AVL was used to calculate simple wings of different aspect ratio A and taper ratio lambda. The Oswald factor was calculated as a function f(lambda) in the same way as shown by HOERNER. Compared to HOERNER's function, the error never exceed 7.5%. Surprisingly, the function f(lambda) was not independent of aspect ratio, as could be assumed from HOERNER. Variations of f(lambda) with aspect ratio were studied and general results found. In a second task, the box wing was investigated. Box wings of different h/b ratio: 0.31, 0.62, and 0.93 were calculated in AVL. The induced drag and Oswald factor in all these cases was calculated. An equation, generally used in the literature, describes the box wing's Oswald factor with parameters k1, k2, k3 and k4. These parameters were found from results obtained with AVL by means of the Excel Solver. In this way the curve k = f(h/b) was plotted. The curve was compared with curves with various theories and experiments conducted prior by other students. The curve built based on AVL fits very well with the curve from HOERNER, PRANDTL and a second experiment made in the wind tunnel at HAW Hamburg.

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