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Studies on Off-Nominal Rotor Aerodynamics for eVTOL Aircraft


Tang, Ellande (2023) Studies on Off-Nominal Rotor Aerodynamics for eVTOL Aircraft. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/eytr-nd50.


As electric Vertical Takeoff and Landing (eVTOL) aircraft become increasingly common, improved understanding of rotor aerodynamics in off-nominal conditions becomes ever more important. A better fundamental understanding of these effects can help inform vehicle design, leading to lower power consumption and improved performance. This thesis will cover a selection of topics to gain a better understanding of the expected rotor aerodynamics associated with use in this class of vehicle, as well as the development of tools to aid in the studies and an analysis of the impact of the effects.

To consider special effects on a rotor in hover on such a vehicle, Chapter 2 is the study of obstructions in the upstream of a propeller, representing the effects of a wing or fuselage blocking a propeller’s inlet. The next is the effect of forward flight on the forces produced by a rotor. Lifting rotors are often used in eVTOL aircraft as the craft transitions to forward flight, so a study of their performance in forward flight as well as a model are presented in Chapter 3. Having examined rotor-wing interactions in hover and isolated rotor performance in forward flight, the next step is to examine rotor-wing interactions in forward flight. Chapter 6 shows the design of an integrated test stand for studying the aerodynamic interactions between lifting propellers and a wing in low-speed, transitional forward flight, as well as the subsequent results.

This thesis also describes the development and implementation of two tools to aid in the work herein. The first (Chapter 4) is a rapid, low-cost method of extracting the geometry of a propeller using photogrammetry which is subsequently used in simulations. The second (Chapter 5) is low-cost and accessible multi-axis force sensor used in the integrated test stand for propeller-wing interaction studies. To assess the impact of the findings, the experimental results and models developed are then taken into consideration by applying them to models of existing eVTOL aircraft in Chapter 7. The change in modeling of hover and transition performance is studied with and without the additional modeling.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:eVTOL; photogrammetry; propeller aerodynamics; propeller-wing interactions; ceiling effect; upstream obstructions
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Mechanical Engineering
Minor Option:Aerospace Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Chung, Soon-Jo
Thesis Committee:
  • Dabiri, John O. (chair)
  • Burdick, Joel Wakeman
  • Tokumaru, Phil
  • Chung, Soon-Jo
Defense Date:15 December 2022
Non-Caltech Author Email:ellandet (AT)
Funding AgencyGrant Number
Center for Autonomous Systems and Technologies at CaltechUNSPECIFIED
Record Number:CaltechTHESIS:12222022-065507477
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for Chapter 6. adapted for Chapter 4. adapted for Chapter 2. adapted for Chapter 3.
Tang, Ellande0000-0001-5933-4716
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15079
Deposited By: Ellande Tang
Deposited On:10 Jan 2023 16:07
Last Modified:17 Jan 2023 16:33

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