Title page for ETD etd-4598-173228

Type of Document Master's Thesis
Author Grasmeyer, Joel M. III
Author's Email Address grasmeye@aoe.vt.edu
URN etd-4598-173228
Title Multidisciplinary Design Optimization of a Strut-Braced Wing Aircraft
Degree Master of Science
Department Aerospace and Ocean Engineering
Advisory Committee
Advisor Name Title
Mason, William H. Committee Chair
Grossman, Bernard M. Committee Member
Schetz, Joseph A. Committee Member
  • Multidisciplinary Design Optimization
  • Aircraft Design
  • Strut-Braced Wing
  • Tip-Mounted Engines
Date of Defense 1998-04-13
Availability unrestricted
The objective of this study is to use Multidisciplinary Design Optimization (MDO) to investigate the use of truss-braced wing concepts in concert with other advanced technologies to obtain a significant improvement in the performance of transonic transport aircraft. The truss topology introduces several opportunities. A higher aspect ratio and decreased wing thickness can be achieved without an increase in wing weight relative to a cantilever wing. The reduction in thickness allows the wing sweep to be reduced without incurring a transonic wave drag penalty. The reduced wing sweep allows a larger percentage of the wing area to achieve natural laminar flow. Additionally, tip-mounted engines can be used to reduce the induced drag. The MDO approach helps the designer achieve the best technology integration by making optimum trades between competing physical effects in the design space.

To perform this study, a suite of approximate analysis tools was assembled into a complete, conceptual-level MDO code. A typical mission profile of the Boeing 777-200IGW was chosen as the design mission profile. This transport carries 305 passengers in mixed class seating at a cruise Mach number of 0.85 over a range of 7,380 nmi.

Several single-strut configurations were optimized for minimum takeoff gross weight, using eighteen design variables and seven constraints. The best single-strut configuration shows a 15% savings in takeoff gross weight, 29% savings in fuel weight, 28% increase in L/D, and a 41% increase in seat-miles per gallon relative to a comparable cantilever wing configuration.

In addition to the MDO work, we have proposed some innovative, unconventional arch-braced and ellipse-braced concepts. A plastic solid model of one of the novel configurations was created using the I-DEAS solid modeling software and rapid prototyping hardware.

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