Continuing the Development of a Physics-Based Weight (PBWeight) Prediction Tool for Conceptual Design: Build 1 (2017)


Tyler Winter, Brent Scheneman, Jose Marquez, Jesse Sidhu


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 (Ref. 1) (Ref. 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 provide a tool to create meta-geometry definitions of internal structure rapidly. The main goal for this effort was 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 OpenVSP, an open source parametric aircraft geometry tool, as well as 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 using OpenVSP, then automatically create FEMs suitable for optimization and generate comprehensive weight statements.

The main objective of this paper is to demonstrate the effectiveness of the PBWeight software tools to create an efficient and user-friendly interface for streamlining the internal structural layout process, assigning material properties, attachments, loads, and optimization analysis information. Evidence will be provided that demonstrates a considerable speed up in time required to create component FEMs for the MD-87 example compared to the time required during the Phase I effort (Ref. 3).

In the following section, a brief overview of the PBWeight process work flow is given. In Section III, a description of the development of the PBWeight GUI and integration within OpenVSP is given. In Section IV, a demonstration of the PBWeight Tool on the MD-87 configuration is provided. In Section V, the example problem description will be described in detail. Finally, in Section VI, the main objectives of our future work will be given.