Date of Thesis

Spring 2019

Thesis Type

Honors Thesis (Bucknell Access Only)

Degree Type

Bachelor of Science in Mechanical Engineering

Major

Mechanical Engineering

First Advisor

Julia A. Cole, Ph.D.

Second Advisor

Craig Beal, Ph.D.

Keywords

urban air mobility, helicopter configuration selection, electric aircraft, helicopter conceptual design

Abstract

Urban air mobility (UAM) refers to the ability to safely and efficiently transport goods and passengers in urban environments using aircraft. To enable UAM, advances in aircraft design and infrastructure are required, spurring an active area of research for both industry and academia. Within this area, Uber Elevate is a program that seeks to establish a network of small, electric, vertical take-off and landing aircraft to alleviate ground traffic and congestion. To support progress in this area, conceptual design methods for electric aircraft for UAM applications are needed. Therefore, the first objective of this thesis was to modify the conventional approach to designing a single-main-rotor helicopter and lift-augmented compound helicopter to account for electric propulsion systems. These processes were then automated for each configuration based on a set of mission parameters including payload, distance, cruise speed, and hover specifications. To verify that the new methods produce reasonable results, sensitivity studies on the main design parameters were performed. Additionally, mission profile data from two existing electric helicopter flights were tested, and the weight, power, and energy results were found to be reasonably similar. Having verified the automated conceptual design approaches, the feasible design space of each configuration was investigated with the overall goal of determining configuration selection criteria based on energy efficiency. For each configuration, ranges of designs for differing mission variables were produced to determine the bounds on each design space. Within the feasible design space, it was found that a crossover boundary exists as a function of cruise distance and hover time where the most efficient configuration changes from a single-main-rotor helicopter to a lift-augmented compound helicopter. In general, for longer cruise distances and shorter hover times, the lift-augmented compound helicopter is the more efficient configuration. For longer hover times and shorter cruise distances, the single-main-rotor helicopter is the more efficient configuration. Overall, this study effectively created conceptual design methods for electric helicopter configurations and investigated the feasible design space based on mission parameters. The results provide selection criteria based on desired mission profile for comparing electric single-main-rotor helicopters and electric lift-augmented compound helicopters for urban air mobility purposes.

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