NASA Ames Research Center (ARC) Aeromechanics Branch hosted more than 60 interns this summer and focused their energies on studying the future of vertical flight. This is the second of two reports from this past years summer interns

Peters, Nicholas J.

NASA Technical Reports Server

During my ten-week NASA Aeromechanics Branch internship, I focused on what is considered by some as the most ambitious and ground-breaking new market of the modern 
aviation industry: urban air mobility (UAM). Even before The Jetsons’ 
first appearance on TV in the early 1960s, the world has hungered 
for a possible future of commuting to work by sky. Yet, what 
started out as a fantasy has slowly turned into an increasingly 
urgent need. The world traffic issues faced in megacities is one 
that results in the loss of billions of dollars a year of productivity 
and one that only continues to worsen with time (see for instance, 
“Traffic Congestion Costs Americans $124 Billion A Year, Report 
Says,” Forbes, Jan. 25, 2015). 
It is this impending megacity gridlock that has led to the business 
case for not only the UAM field but an overarching goal across the 
industry to establish alternative forms of transportation for the 
modern urban environment. Yet, with each of these plans, there 
are selective enabling technologies that act as limiters to their 
mass market application, and the UAM market is no different. 
Currently, eVTOL.news — the VFS website on electric vertical 
takeoff and landing (eVTOL) aircraft — lists more than 125 
proposed UAM-styled aircraft established by companies ranging 
from startups to the largest players of aviation (e.g. Airbus, Bell, 
Boeing and Embraer). Nearly all of these concepts propose using 
enabling technologies such as fly-by-wire-based control laws, 
electric or hybrid propulsion, and advanced structures and 
manufacturing techniques.
With a large array of technologies still needing to be studied, there 
is a clear need for a financial incentive to speed the practical 
application of these technologies. Here is where the GoFly Prize 
enters the UAM field. The GoFly competition requires that selected 
teams design and fly minimally-small “personal flying devices” that 
can incorporate VTOL technologies into their design (see “GoFly 
Enters Phase II,” Vertiflite, July/Aug 2018 or www.goflyprize.com). 
While each team is competing for $2M in prizes and the hopes 
of developing a marketable product, the collective information 
provided by the teams will form the foundation on which a future 
UAM market for individual transportation could grow.
To date, the competition has completed its first phase and has 
selected 10 winners. It is clear that these teams were selected 
By Nicholas Peters
NASA Ames Research Center (ARC) 
Aeromechanics Branch hosted more than 
60 interns this summer and focused their 
energies on studying the future of vertical 
flight. This is the second of two reports from 
this past year’s summer interns.
What Else to 
Do with an 
Army of Interns
Top: Artistic rendering of the Silverwing team’s S1. 
Bottom: Ethen Krings’ resized version of the S1.
Final rendering of the Hummingbuzz as constructed by 
Makynzie Zimmer.
Example of 
image with 
pilot used 
scaling. Here 
Makynzie 
Zimmer used 
an average 
sized femur 
to scale 
Georgia Tech’s 
Hummingbuzz 
aircraft.
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https://ntrs.nasa.gov/search.jsp?R=20190025426 2019-08-31T12:01:15+00:00Z
Final rendering 
of the Blue 
Sparrow as 
constructed by 
Mireille Fehler.
Final rendering 
of the Harmony 
as constructed 
by Michaela 
Sorrentino.
both because their proposed aircraft represented a practical 
demonstrator and because they appeared capable of seeing their 
project to completion. However, what may not be so clear is the 
feasibility of each aircraft selected. With new proposals for eVTOL 
aircraft being posted on the eVTOL.news directory on almost 
a daily basis, the rotorcraft community has the opportunity to 
consider the feasibility of these aircraft. In his Sept/Oct Vertiflite 
Commentary, “Beware the Hyper-Hype Cycle,” VFS Executive 
Director Mike Hirschberg warned of over-expectation: “While 
a few early entrants — most notably Ehang, Joby Aviation, Kitty 
Hawk, Opener and Volocopter — have conducted robust flight 
testing, including manned flights, the vast majority of innovators 
are still discovering the unique challenges of vertical flight.” A lack 
of analysis into potentially unrealistic claims made by emerging 
manufacturers could possibly lead to an over-expectation of 
where the UAM field currently is. This could potentially lead to a 
hindrance of the market in the long run. As such, the internship 
directors decided that it would be worthwhile to dedicate a 
significant portion of the summer program for my peers and me to 
conduct feasibility analyses of each of the Phase I winning aircraft 
for the GoFly competition. 
Before feasibility could be considered, the team of interns first had 
to accurately model each of the ten winners. These reconstructed 
models for the aircraft were based on images open to the public. In 
attempting to properly scale these models, the teams positioned 
3-D computer models of pilots based on average-sized adults 
into the aircraft for use as a reference. It should be noted that 
many of the images initially used as the templates were designed 
with more emphasis on artistic rendering than on practical 
engineering (for competitive reasons the teams weren’t required 
to provide accurate images). Given this, it was evident that some 
of the components of the aircraft would need to be sized through 
computational analysis. As such, a low-fidelity conceptual design 
process was undertaken that would provide the team with power 
and fuel requirements for the aircraft based off a simple mission 
with a one-minute hover and 20 minutes of cruise. The basic 
objective of this step was to complete an energy balance by first 
finding the power required for each flight condition and then, 
with power and time, determining the energy required for the 
total mission.
However, before a conceptual mission analysis could be completed, 
the team first needed an initial estimate of weights to start their 
energy balance. This initial guess was completed by applying 
materials to the computer-aided design (CAD) solid models in 
Dassault Systèmes Solidworks and finding material weights. After 
the mission analysis was completed, the team took its findings for 
fuel weights and power requirements, and resized its aircraft with 
the necessary volume for both the properly-sized motors and fuel. 
This iterative process was repeated until the change in volumes 
were small enough to be considered converged. 
At the conclusion of this analysis, there were no red flags raised 
warning against feasibility for any of the ten aircraft. However, 
there was much that was not considered by this simple energy-
based weight balance that still needed to be considered. There 
was minimal consideration of component sizing, structures, 
safety margins, rotor-to-rotor interactions, controllability, etc. 
In short, only the bare minimum was considered and as such it 
became evident that a much deeper analysis was needed in order 
to validate the feasibility for these aircraft with more certainty. 
To this end, the NASA Design and Analysis of Rotorcraft (NDARC) 
conceptual design software was employed. 
About the Author 
Nicholas Peters is a first semester PhD student at Embry-Riddle 
Aeronautical University in Daytona Beach, Florida. During his 
internship with NASA Ames, Nick worked under Chris Silva 
while employing the conceptual design software NDARC to 
undergo a feasibility analysis of several UAM concepts. He 
hopes to continue working within the emerging UAM field as it 
continues to grow.
I would like to recognize the modeling group whose work 
allowed for the feasibility analysis of all 10 aircraft. Their 
hard work also helped me to obtain as accurate as possible 
geometric inputs for the NDARC software without having to 
obtain the actual CAD models from each GoFly team. These 
team members were Makynzie Zimmer, Ethan Krings, Michaela 
Sorrentino, James Gayton, Lauren Wagner, Hannah Dromiack 
and Mireille Fehler. As part of a summer high school program, 
two high school interns also help contributed to the project: 
Bianca Ortiz-Larios and Courtney Young. 
By the end of the ten-week internship, all 10 aircraft had NDARC 
files constructed with estimated weights and sizes. To maintain 
the integrity of the competition, the specific numerical results 
from this investigation for each of the competitors will not be 
published. However, what can be shared is that the findings of 
this secondary investigation did show that all the aircraft in fact 
should be able to complete their specified missions with at most 
minor alterations. What this study suggests is that all ten teams 
have the potential for viable demonstrators that can push the 
limits of modern VTOL engineering.
But what is possibly more important is the impact each of these 
teams will have on the UAM market as a whole. It’s true that 
the construction of these small personal flying devices will 
not result in the immediate future an eVTOL aircraft capable 
of carrying multiple passengers around megacities. Yet, what’s 
also true is that the work that the teams are doing will lay the 
foundation so that the eventual future of the UAM market 
will be possible.
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What Else to Do with an Army of Interns

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