Ph.D. Defense: Colby J. Weit

Tue Aug 17 2021 11:00 AM
"A System-of-Systems Approach to Aerospace Systems Design Decision-Making"

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Ph.D. Defense


Colby J. Weit

(Advisor: Prof. Dimitri N. Mavris)


"A System-of-Systems Approach to Aerospace Systems Design Decision-Making"


Tuesday, August 17
11:00 a.m.



Aviation is a very complex industry. Since the Wright brothers first overcame the challenges of heavier-than-air, powered flight in the early 1900s, global aviation has grown into a global powerhouse industry with the total number of passengers serviced in 2019 eclipsing 4.6 billion. This advancement has not come without challenges. A review of the aviation industry and engineering design therein reveals that aviation has evolved into a complex system-of-systems exhibiting recognizable and defined system-of-systems characteristics. In addition to the historical complexity inherent in the growth of global aviation, the forward-looking horizon of aviation and aerial mobility shows burgeoning, disruptive classes of vehicles such as commercial and business jet supersonic transports, urban air mobility, and regional electrified aerial mobility (among others). Improperly considering the system-of-systems into which legacy and new classes of vehicles enter can yield disjointedness between the conceptual design process and the actual integration into the system-of-systems. Recent programs, the Boeing 787 and the Airbus A380 both, faced many obstacles in their development while racing to market in the first decade of the 21st century related to their major market targets and design decisions. Although the 787 has recovered and become a largely successful commercial airplane, the A380 program is to be terminated in 2021. These ventures and their associated outcomes fortify the need to ‘get things right" the first time for the major domains of the aviation system-of-systems: the resources, the economics, the operations, and the policy and sustainability. Consideration of any of these domains unilaterally can and likely will result in overall shortcomings and missed opportunities when a system design solution integrates into the overall system-of-systems. This point is even more critical for new classes of vehicles which are targeting novel concepts of operation and infrastructure integration. A research objective is chartered to develop a methodology to enable enhanced design decision-making in conceptual system design by considering the holistic aviation system-of-systems.

A review of design decision-making, systems design, and existing design frameworks reveals four key gaps that prevent the objective methodology from being met by work already established in literature. These four gaps include a lack of formalism for mapping system-of-systems domains to design requirements, a missing capability for evaluating trade-offs between operation and technology alternatives in design, an un-utilized capability in using modeling and simulation at the SoS-level for design and design decision-making purposes, and an un-utilized capability of capturing system-of-systems uncertainty in design decision-making with a scenario development process. A synthesis of the unfulfilled research objective and the identified gaps leads to a need to formulate this methodology as original work. It is hypothesized that a model-based methodology connecting requirements, vehicle concepts, operations, and technologies at the system-level with a quantitative representation of the system-of-systems provides novel information for design decision-making and satisfies the research objective for sufficient design decision-making enhancement in the context of the holistic system-of-systems.

This need is met by formulating a 6-Step Methodology for Design Decision-Making Using a Holistic System-of-Systems Approach (MeDUSA) that establishes the need and value, defines the problem, builds baseline vehicle-level and fleet-level models, conducts design space exploration, evaluates feasibility and viability, identifies alternatives, generates and evaluates alternatives, and conducts design decision-making. Each of the four gaps identified lead to a specific capability development activity and integration into the overall MeDUSA methodology to support the desire to conduct design decision-making in the SoS context.

The methodology developed in this thesis is demonstrated on a commercial supersonic transport (SST) airplane. A notional market need is established and justified for a Mach 2.2, 55 passenger SST, and the MeDUSA methodology is employed step-by-step to demonstrate how each of the capabilities contributes to a collective consideration of the holistic aviation system-of-systems and how the convergence of the information generated by those capabilities yields meaningful insights and causalities to be used in decision-making that are not previously available and actionable.

The contributions of this work include (a) a methodology to improve design decision-making by considering the holistic system-of-systems within when the concept system resides and (b) capability development in support of the formulation and demonstration of the methodology for mapping system-of-systems domains to requirements, SoS modeling and simulation for design, technology/operation alternative trade-offs, and using scenario-development to support SoS uncertainty capture. These capabilities do not currently exist before the formulation, development, and implementation of the MeDUSA methodology.



  • Prof. Dimitri N. Mavris – School of Aerospace Engineering (advisor)
  • Dr. Michelle R. Kirby – School of Aerospace Engineering
  • Prof. Lakshmi N. Sankar – School of Aerospace Engineering
  • Prof. Daniel P. Schrage – School of Aerospace Engineering
  • Dr. Matthew W. Orr – Associate Technical Fellow, Boeing Commercial Airplanes