Till Pfeiffer

On the Design of a Strut-Braced Wing Configuration in a Collaborative Design Environment

Due to its drag saving potential through application of high aspect ratio wings, the strut-braced wing configuration is considered a promising candidate as a next generation single-aisle aircraft. This potential is reflected in the results of the renowned Sugar and Albatross projects of Boeing and ONERA. In the course of DLRs project future enhanced aircraft configurations (FrEACs), a strut-braced wing configuration is examined with focus on the interaction of aerodynamics, loads, structures and aeroelastics. The present study outlines the applied design process for the strut-braced wing configuration in DLRs collaborative design environment and highlights lessons learnt from an organizational and technical point of view. It proves that the level of confidence in the design process is largely increased by effectively combining both the explicit and implicit knowledge of the heterogeneous specialists involved. The explicit knowledge is incorporated through automated execution of the specialists tools in structured simulation workflows. Implicit knowledge of the specialists is required to interpret results both in the respective disciplinary context as well as on overall aircraft design level. Applying the collaborative design process enables statements on the possible gain of strut-braced wing over conventional tube and wing configurations. The paper describes the applied collaborative design procedure, shows results concerning the physical aspects of the strut-braced wing configuration and concludes by providing lessons learnt and an outlook into the application of collaborative design.

Stability and Control Investigations in Early Stages of Aircraft Design

This paper provides an overview of current activities of DLR (German Aerospace Center) with respect to stability and control investigations in the context of early stages of aircraft design. For this purpose, DLR follows an interdisciplinary and multi-level design approach. Using an integration framework in combination with a central data exchange format, largely automated process chains are set up that combine calculation and simulation capabilities of the multitude of disciplines required in early aircraft design. Rather than using empirical relations and assumptions based on experience, the underlying methods applied by the tools are mainly based on physical model representations. The major aim of this design approach is to generate all relevant data needed for stability and control investigations, including aerodynamic damping derivatives and to assemble them within a flight dynamics model. Not only does this approach allow for an early consideration of stability and control characteristics, but it also respects interdisciplinary effects and enables automated design changes. This paper describes the infrastructure used for setting up the described process. It presents disciplinary tools used to calculate engine performance maps, calculate aerodynamic performance maps and structural properties, generate flight dynamics models with associated control laws and to assess aircraft handling qualities. Furthermore, this paper provides application examples of early stability and control considerations, using integrated interdisciplinary process chains. This comprises a handling qualities assessment under uncertainty considerations and vertical tailplane sizing for a blended wing body. In addition, engine and split flap sizing processes for an unmanned combat aerial vehicle are shown. The interdisciplinary design approach presented here, serves to find a well justified early configuration and reduces the risk of later design changes.