Continuing the Development of a Physics-Based Weight (PBWeight) Prediction Tool for Conceptual Design: Build 2 (2017)


Tyler Winter, Brent Scheneman, Donovan Fung, and Phillip Chung


Many critical challenges currently exist for designing, developing, and analyzing physics-based conceptual aircraft design tools. 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 [ 1] [ 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 further developed the PBWeight software to enhance the current capabilities of the software as well as add new enhancements in an effort to build a complete weight statement for unconventional (and conventional) conceptual designs. The main goal for this effort was primarily to streamline the internal structural layout process for conventional and unconventional designs. The core of the PBWeight software is built upon three key software components. First is OpenVSP, which is an open source parametric aircraft geometry tool capable of rapidly creating geometry OMLs. Second is RapidFEM, a previously developed tool capable of automatically generating geometry and Finite Element Models (FEMs) of complex built-up structures for rapid concept evaluation and structural optimization. The last software component is the RapidFEM Sketch File Editor, an efficient and user-friendly interface for streamlining the internal structural layout process, assigning material properties, attachments, loads, and optimization analysis information.

The main objective of this paper is to describe the new additions to the PBWeight software tools aimed at increasing the efficiency and usability of the interface for streamlining the internal structural layout process, assigning material properties, attachments, loads, and optimization analysis information.

In the following section, a brief overview of the PBWeight process work flow is given. In Section III, an overview of the Automated Wing and Fuselage Layout Tools that were integrated within OpenVSP is given. In Section IV, explanations of the added capabilities to the RapidFEM Sketch File Editor, including the RapidFEM BEAM Paver Tool and RapidFEM SKIN4 Paver Tool will be provided. In Section V, an examination of the Parametrically Driven Trade Study Engine will be given. Finally, in Section VI, conclusions and future work are discussed.