Danielle Soban

HTS machines as enabling technology for all-electric airborne vehicles

Environmental protection has now become paramount as evidence mounts to support the thesis of human activity-driven global warming. A global reduction of the emissions of pollutants into the atmosphere is therefore needed and new technologies have to be considered. A large part of the emissions come from transportation vehicles, including cars, trucks and airplanes, due to the nature of their combustion-based propulsion systems. Our team has been working for several years on the development of high power density superconducting motors for aircraft propulsion and fuel cell based power systems for aircraft. This paper investigates the feasibility of all-electric aircraft based on currently available technology. Electric propulsion would require the development of high power density electric propulsion motors, generators, power management and distribution systems. The requirements in terms of weight and volume of these components cannot be achieved with conventional technologies; however, the use of superconductors associated with hydrogen-based power plants makes possible the design of a reasonably light power system and would therefore enable the development of all-electric aero-vehicles. A system sizing has been performed both for actuators and for primary propulsion. Many advantages would come from electrical propulsion such as better controllability of the propulsion, higher efficiency, higher availability and less maintenance needs. Superconducting machines may very well be the enabling technology for all-electric aircraft development.

HTS motors in aircraft propulsion: design considerations

Current high temperature superconducting (HTS) wires exhibit high current densities enabling their use in electrical rotating machinery. The possibility of designing high power density superconducting motors operating at reasonable temperatures allows for new applications in mobile systems in which size and weight represent key design parameters. Thus, all-electric aircrafts represent a promising application for HTS motors. The design of such a complex system as an aircraft consists of a multi-variable optimization that requires computer models and advanced design procedures. This paper presents a specific sizing model of superconducting propulsion motors to be used in aircraft design. The model also takes into account the cooling system. The requirements for this application are presented in terms of power and dynamics as well as a load profile corresponding to a typical mission. We discuss the design implications of using a superconducting motor on an aircraft as well as the integration of the electrical propulsion in the aircraft, and the scaling laws derived from physics-based modeling of HTS motors.

An application of a technology impact forecasting (TIF) method to an uninhabited combat aerial vehicle

Presented at the 4th World Aviation Congress and Exposition, San Francisco, CA, October 19-21, 1999.

A Generalized Aircraft Sizing Method and Application to Electric Aircraft

Internal combustion (IC) engines, which consume hydrocarbon fuels, have dominated the propulsion systems of air-vehicles during a century of aviation history. In the past decade, however, a combination of environmental, technological, and socio-economic changes have stimulated the search for new, alternative sources of power that could challenge the dominance of the IC engine. In particular, fuel cells are increasingly being considered as an alternate power source due to their potential advantages over the traditional power system. Nevertheless, traditional aircraft sizing methods currently employed in the conceptual design phase are not immediately applicable to such revolutionary power drive aircraft designs. Motivated by such deficiencies in state-of-the art sizing methods, a generalized aircraft sizing method has been developed as a solution to this challenge. A brief outline of the method and preliminary results from its application to an electric high altitude long endurance (HALE) configuration are provided in this paper.

Assessing the Impact of Technology on Aircraft Systems Using Technology Impact Forecasting

In today’s atmosphere of constrained defense spending and reduced research budgets, determining how to allocate resources for research and design has become a critical and challenging task. In the area of aircraft design, there are many promising technologies to be explored, yet limited funds with which to explore them. In addition, issues concerning the uncertainty in technology readiness, as well as the quantification of the impact of a technology (or combinations of technologies), are of key importance during the design process. This paper presents a methodology that details a comprehensive and structured process in which to quantitatively explore the effects of technology for a given baseline aircraft. This process, called technology impact forecasting, involves the creation of an assessment environment for use in conjunction with defined technology scenarios, and it will have a significant impact on the resource allocation strategies for defense acquisition. The advantages and limitations of the meth...

Design of a UAV to Optimize Use of Fuel Cell Propulsion Technology

*† An increased interest in reducing the environmental impact of aircraft while increasing overall efficiency has driven research into fuel cells for use in propulsion systems for aircraft. Instead of retrofitting an existing system with a fuel cell power system in the course of the design process, this work seeks to use the par ticular characteristics of fuel cells to instead drive the selection of a vehicle that can then be optimized into a finished design. This essentially involves a reversal of the traditional design process and involves the development of a new set of tools that can be used to analyze the miss ion-level impact of a propulsion system technology on a set of vehicle classes. The paper outlines the new mapping technique, including descriptions of fundamental qualitative analysis tools. The final interactive assessment environment is presented, and is used to map fuel cell technologies to UAV vehicle classes.

Power Based Sizing Method for Aircraft Consuming Unconventional Energy

Presented at the 43rd AIAA Aerospace Sciences Meeting and Exhibit, Reno, Nevada, Jan. 10-13, 2005.

Creation of a Design Framework for All-Electric Aircraft Propulsion Architectures

This paper summarizes the achievements of a research-in-progress that aims to create an integrated design framework for all-electric aircraft propulsion architectures. The examination of modeling approaches towards parametrically designing, analyzing, and sizing an example electric aircraft propulsion architecture is presented as the preliminary investigation into this ideology. Lessons learned from this study is envisioned to help identify those areas in which new methodological contributions can be made.

Methodology for Assessing Survivability Tradeoffs in the Preliminary Design Process

Presented at the 5th World Aviation Congress and Exposition, San Diego, CA, October 10-12, 2000.

Developing a Capability Function Relating Aircraft Systems Cost Overruns to Aircraft Design Parameters

Cost overruns and delays are threatening the economic stability of aerospace programs. In order for programs to be successful overruns in cost and time must be eradicated or managed effectively through realistic Life Cycle Costing methodologies. Being aware of their impact at the earliest stage of development ensures that realistic budgets can be assigned and potential problems can be identified and planned for before they major issues. Using Life Cycle Costing methodologies, the basis of a new capability function aimed at accounting for cost overruns and delays upfront within life cycle management procedures will be introduced. Using gathered data, the main drivers of cost and delay will be identified and their effect on Life Cycle Cost assessed before being included within the new function which aims to achieve the highest economically valuable aircraft and program through the application of value engineering principles.