Tyler Winter, Jose Marquez, Brent Scheneman
Many critical challenges currently exist for designing, developing, and analyzing physics-based conceptual aircraft design tools. Often engineers struggle with determining the appropriate levels of fidelity in models or techniques (e.g. reduced order) to be used in the conceptual design phase. One challenge of particular relevance to the current effort is the desire to accurately and efficiently predict weights and loadings for unconventional designs. Unconventional designs are required to break through the common or ‘expected’ limitations associated with conventional designs. Furthermore, the ability to assess, in a rapid manner, the feasibility of these unconventional designs is crucial to NASA’s Environmentally Responsible Aviation (ERA) project as well as many other efforts seeking to develop enabling technologies required to solve a variety of important design problems (high lift-to-drag ratios, community noise, reduced drag, etc.). The Blended Wing Body (BWB) or Hybrid Wing Body (HWB) aircraft, for example, has been researched and analyzed for many years as an unconventional efficient transport configuration.
Approaches for weight prediction in the conceptual design phase typically consist of parametric relations or empirical databases (Refs. 1 and 2). Historical databases work reasonably well when applied to existing or conventional designs, however, they fail to predict accurately the weights and loads associated with unconventional designs (like the BWB). There exists a need to augment existing historical databases with a physics-based methodology/capability for predicting the weights and loads of unconventional designs.
In the current effort, M4 Engineering has developed and evaluated the feasibility of an innovative concept aimed at enhancing previously developed databases with physics-based weight and load estimation relationships for unconventional (and conventional!) conceptual wing and fuselage designs. The main goal for this effort will be to develop a software tool capable of generating weight and load responses for unconventional designs from physics-based simulations. In an effort to minimize risk and expedite development, the PBWeight software utilizes a previously developed tool (RapidFEM) to automatically generate geometry and Finite Element Models (FEMs) of complex built-up structures for rapid concept evaluation and structural optimization. The PBWeight software allows a user to specify conceptual design-level information about wing and fuselage structures, then automatically create FEMs and generate relationships (response surfaces) for weights and loads.
In the following section, a brief description of the demonstration configurations analyzed with the PBWeight software is given. In Section III, an overview on the physics-based weight prediction process will be outlined. In Section IV, the details of the configuration development procedure will be given. In Section V, the example problem descriptions and optimization results will be described in detail for each configuration. Finally, in Section VI, the main objectives of our future work will be given.