PhD Defense by Jeremy Epps

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Jeremy Epps
(Advisor: Prof. Eric Feron)

will defend a doctoral thesis entitled,

Rotor-rotor Interactions in the Design of Unmanned Aerial Systems


Tuesday, June 14 at 1:30 p.m


This dissertation investigates the impact of rotor-rotor interactions on small Unmanned Aerial System (UAS) design. This work aims to investigate the aerodynamic effects of two rotor configurations, the first being non-coplanar overlapping rotors, tandem-rotors, and the second being the semi-coaxial rotor configuration, which is an adaptation of the traditional coaxial rotor configuration. This work is motivated by three UAS, two of which, the Tetracopter and the Dodecacopter, are designed and developed as a part of the work presented in this dissertation. The Tetracopter and Dodecacopter are multi-agent vehicles that implement multiple layers of non-coplanar overlapping rotors. The goal of these two vehicles is to implement a design where a multi-agent UAS can have the structural rigidity to withstand carrying payloads, whether the payload is carried above or below the vehicle, while being as efficient as a multi-agent aircraft with coplanar rotors. The goal of the Y6sC is to show that the semi-coaxial rotor configuration allows a vehicle to be more efficient in hover than a traditional coaxial rotor configuration and that the semi-coaxial rotor configuration grants the vehicle more maneuverability than a traditional coaxial rotor configuration.

This dissertation can be separated into two halves; the first half begins with the presentation of a thrust stand fabricated to collect data on both rotor configurations. This half also discusses the methods used to conduct these thrust stand experiments, the methods used to analyze the data, and discussions about the results and their comparison to established theories that predict the performance of these rotor configurations. A rotor configuration performance estimation method that is based on the empirical data collected is also presented, and the accuracy of this estimation method is validated. This estimation method is then used to estimate the optimal design of the Tetracopter and Dodecacopter, which accounts for the vehicle's weight and the performance of the vehicle's rotors which may be impacted by rotor-rotor interactions.

The latter half of this dissertation discusses the design of the Dodecacopter along with the methods used to flight test the vehicle. The data produced from the flight tests are discussed, and estimations of the degradation in the performance of the vehicle due to the rotor-rotor interactions are presented and discussed. The dissertation concludes with a brief discussion on the design implications derived from the results of the work presented.


  • Prof. Eric Feron – Electrical and Computer Engineering, King Abdullah University of Science and Technology (advisor)
  • Prof. Marilyn Smith– School of Aerospace Engineering, Georgia Institute of Technology
  • Prof. Jonathan Rogers – School of Aerospace Engineering, Georgia Institute of Technology
  • Prof. Eric Johnson – School of Aerospace Engineering, Pennsylvania State University
  • Prof. Javier Irizarry – School of Building Construction, Georgia Institute of Technology



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    Tatianna Richardson
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    Tatianna Richardson
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