A Comprehensive Research on Electric Vertical Take-Off and Landing Aircraft for Advanced Air Mobility

Developing RISPECT+ code for eVTOL aircraft performance analysis and design in AAM

Developing an improved technology portfolio assessment methodology

Modeling for AAM aircraft cost and demand forecasting

Establishing a system-level design framework for AAM aircraft

Professor Kwanjung Yee, from the Department of Aerospace Engineering, has conducted extensive research in the field of Advanced Air Mobility (AAM), which is a type of smart mobility that has recently received significant attention. His research encompasses performance analysis, conceptual design, demand and cost analysis, and system-level design for AAM. Throughout his research, he has developed various codes and frameworks.
In recent years, advancements in electrical technologies, including electric motors, batteries, and controllers, have opened up new possibilities for electric vertical take-off and landing (eVTOL) aircraft, making them a promising solution for AAM. eVTOL aircraft are preferred for their reduced noise, enhanced safety, and lower carbon footprint compared to traditional VTOL aircraft. There are currently over 450 eVTOL aircraft in development, a trend sparked by Uber's 2016 Elevate White Paper, which generated significant interest in this field.
With the electrification of propulsion system, eVTOL aircraft can adopt distributed propulsion systems, significantly increasing design diversity compared to conventional internal combustion engine-based VTOL aircraft. eVTOL aircraft can have a range of configurations, such as wingless, lift plus cruise, and vectored thrust, along with diverse propulsion systems, including battery, hybrid-electric, and fuel cell. Therefore, the ability to consider these configurations and propulsion systems is crucial in designing eVTOL aircraft. To design eVTOL aircraft while accounting for these defining characteristics, Professor Yee has developed RISPECT+ (Rotorcraft Initial Sizing and Performance Estimation Code and Toolkit+), a versatile conceptual design framework for eVTOL aircraft in AAM. RISPECT+ enables the analysis and design of various eVTOL aircraft types.
Typically, aeronautical systems have a long development timeline, starting from the concept study and leading to Entry into Service (EIS), followed by an extended operational life cycle. This lengthy life cycle of aircraft implies that the conceptual and preliminary design phases occur much earlier before the aircraft becomes operational. To meet the future Voice of Customer (VOC) and avoid obsolescence at the EIS date, all available technologies should be considered in the conceptual design phase, even if some of them are relatively immature at that time. To this end, Yee has developed an improved technology portfolio assessment methodology to explore the available technology space and assist project leaders in making a decision during the earlier design phases.
Indeed, even if the design of eVTOL aircraft is made feasible through advancements in relevant technologies, it is imperative to assess the necessity of urban air transportation as a mode. Evaluating the demand and profitability of the designed eVTOL when deployed in an urban setting is crucial. To achieve this, demand and cost analysis tools are indispensable for considering the demand and profitability of eVTOL operations. In pursuit of this objective, Professor Yee has developed AC2 (Aircraft Cost Analysis Code), an eVTOL cost analysis tool, and MADAM_D (Multidisciplinary Analysis and Design for Advanced Mobility - Demand), an eVTOL demand analysis tool. These resources offer insights into the level of demand generated at specific ticket prices and the resulting profitability of eVTOL operations.
The rapid advancements in electric propulsion technologies have broadened the applications of various advanced mobility including AAM aircraft, introducing a variety of operational environments on land, sea, and in the air. Professor Yee has developed a systematic, mission-oriented design process to address these evolving needs, resulting in the creation of CoDeF (Comprehensive Design Framework for Advanced Mobility). CoDeF is a robust platform designed to facilitate the efficient development of diverse unmanned vehicles and AAM aircraft, ensuring each design is optimized for performance, safety, noise, and other factors. Professor Yee’s contributions, including RISPECT+ and CoDeF, are poised to play a pivotal role in shaping the future of a mobility ecosystem marked by innovation, efficiency, and improved performance.
Professor Yee continues to conduct research related to eVTOL aircraft for AAM. His ongoing research includes developing a battery sizing methodology for eVTOL aircraft that considers the thermal effects of battery and creating a method for analyzing the handling quality of eVTOL aircraft.

Figure 1 Tested vehicle configuration and physical parameters (left), 3-D scatter plot of the
effectiveness indices, and RDT&E (Research, Development, Test, and Evaluation)
cost (right).

Figure 2 Demand analysis results for metropolitan area (left), Ongoing research related to the
development of battery sizing method considering thermal effects (right).


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