Opening the Skies to Urban Air Mobility

E M B R Y - R I D D L E E N G I N E E R I N G


Concept rendering of Embry-Riddle’s new personal air vehicle, known as PAV-ER.

02 Electrifying the Third Revolution in Aircraft Propulsion 09 Distributed Electric Propulsion is Highlight of New Air Vehicle 14 The Next Major Aerospace Market 18 Influencing Key Revisions to FAA Regulations for UAM Development 20 Who will Fly the Aerial Vehicles of Tomorrow? 23 Featured Alumni 24 Noise Remains a Top Challenge for Making Air Taxis a Reality 25 Milestones in Innovation O P E N I N G T H E S K I E S T O U R B A N A I R M O B I L I T Y




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in Aircraft Propulsion 02


Electrifying the Third Revolution

Dr. Richard “Pat” Anderson Professor of Aerospace Engineering Director of the Eagle Flight Research Center Chief Technology Officer, VerdeGo Aero (Ph.D. University of Central Florida) Eric Bartsch Chief Executive Officer, VerdeGo Aero & Tenant Partner, Embry-Riddle Research Park

Dr. Borja Martos Research Engineer, Eagle Flight Research Center



& President, Flight Level Engineering (Ph.D., University of Tennessee-Knoxville)

Dr. Maj Mirmirani College of Engineering Dean & Professor (Ph.D., University of California System, Berkeley)

Editor + Writer Kelly Pratt

Senior Graphic Designer Crystal Davis

Senior Multimedia Manager Robin Adney

Contributor Jon O’Neill

Embry-Riddle Aeronautical University | College of Engineering 1 Aerospace Boulevard | Daytona Beach, FL, 32114

Photographers Daryl Labello + David Massey

386.226.6917 | |

Ten years hence, batteries aren’t nearly where people were hoping they would be in supplying sufficient energy density to power a flying vehicle for any practical range and speed. Hybrid-electric proved to be the powerplant of choice for researchers and has inspired a new hybrid electric powerplant project at Embry-Riddle that possesses nearly five times the energy density of a similar battery-powered system. In the years since the competition, we also developed an electrically powered technology demonstrator, which uses novel control algorithms and propeller mechanisms to transition between flight regimes. This trailblazing patented technology is certain to open the door for more widespread use of vertical take-off and landing (VTOL) vehicles and usher a new era in UAM. Innovation is often balanced with advocacy work for airworthiness standards and certification updates. Thanks to our efforts, the General Aviation Manufacturers Association — a highly influential global trade organization — established a committee on Electric Propulsion, which is chaired by Professor Richard “Pat” Anderson. We also established a university- led Hybrid Electric Research Consortium to study the technology’s potential and challenges with our growing membership, inclusive of Airbus and Argonne National

Dean’s Column

In this special College of Engineering publication, we focus on the emerging industry of urban air mobility (UAM) — on-demand, short range air travel over an urban area. Flying autonomous vehicles have been on the ascending side of Gartner’s Hype Cycle for the past two years, according to the organization’s emerging technology trends. However, for UAM to fully realize its promise, it requires the confluence of autonomy and other enabling technologies — including high-energy density and quiet electrified propulsion. In order to become commercially viable, a supportive ground infrastructure must be developed. The technology must also achieve extreme operational reliability to satisfy regulatory requirements and gain public acceptance. In this publication you will find insightful perspectives on all aspects of UAM by Embry-Riddle’s experts and pioneers, who, through their research, are shaping the direction of this potentially disruptive technology. As a leading aerospace and aviation institution, Embry-Riddle plays a central role in the rapidly growing industry’s R&D through its Eagle Flight Research Center. A natural synergy occurs between the center and the cluster of innovative UAM startups in the university’s Research Park, such as VerdeGo Aero, Flight Level Engineering and Aerial Applications. Our expertise in UAM is a decade in the making. The NASA Green Flight Challenge we entered in 2011 required flying an aircraft for 200 miles from takeoff to landing on the energy equivalent of one gallon of gasoline. We selected a hybrid electric architecture for the powerplant installed on one of the most aerodynamically efficient airframes — a Stemme S-10 — instead of going for a fully electric vehicle.

“These investments empower

Embry-Riddle to continue pushing

the envelope on autonomy and eVTOL technology.”

Laboratory, to name a few. These investments empower

Embry-Riddle to continue pushing the envelope on autonomy and eVTOL technology, both critical for the realization of UAM. I hope you enjoy reading about the advancements we have made in this emerging industry.


Maj Mirmirani, Ph.D. Dean & Professor College of Engineering

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By Richard “Pat” Anderson, Ph.D.

How three groundbreaking projects set up Embry-Riddle to take on urban air mobility.


in Aircraft Propulsion

Urban air mobility (UAM) is both an exciting and, for some, a daunting emerging area in technology and business. I have never in my lifetime seen the flow of what is fast becoming billions of dollars in non-aerospace investment capital into an aircraft industry. At Embry-Riddle we are investigating the underlying physics of what the media calls “flying cars” with directed research that started over a decade ago. We are working to sort out the myths from the reality. We have seen our version of market bubbles; unmanned aircraft systems, for example, have not met all of the market hype. We have noted the failures — most famously seen in the Vertical Flight Society’s “Wheel of Misfortune,” which shows countless orphaned VTOL projects. Yet there is reason for optimism in this transformative technology currently under development at the Eagle Flight Research Center. Electrified aircraft propulsion is the third revolution in aircraft propulsion since jet engines and early gasoline engines. It will enable both more environmentally friendly commuter aircraft and transformative mobility in urban settings.

Dr. Anderson is a commercial pilot,

aerospace engineering professor and director of the Eagle Flight Research Center at Embry-Riddle, where he led the development of the world’s first manned piston gas/ electric hybrid aircraft program and supervises the R&D for new vehicle concepts, advanced flight controls and novel certification strategies.

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The Eco Eagle is the world’s first direct drive hybrid gas/electric aircraft.

The Diamond HK-36 is powered by a fully electric battery.

Embry-Riddle entered the only hybrid aircraft into NASA’s Green Flight Challenge.

Over the course of the past decade, three groundbreaking projects have set up the university’s aerospace design and research facility to help power this concept into a reality. Building on our past experiences, we went from developing the first-ever parallel hybrid aircraft, to modifying a Diamond HK-36 into a fully electric aircraft, followed by an unmanned VTOL vehicle that essentially taught itself to fly. Today, the technologies and lessons learned culminate with the university’s first UAM vehicle, currently under construction, and a new hybrid powerplant capable of delivering five times more electric power-to-weight than any existing battery system. Sustainability Competition Leads New Propulsion Research Our research in this space began in 2010 with our entry into NASA’s Green Flight Challenge, a competition to exceed 200 passenger miles per gallon at over 100 mph over a course that was 200 miles long. While we did not win the challenge, we entered the contest with the world’s first parallel hybrid aircraft, which is proving to be a more useful concept for commercial development and also set the stage for more propulsion research.

Coming away from the competition, it was clear that there was an opportunity to transform aircraft design using new methods of propulsion that could not only be greener than current aircraft, but could also allow missions to be flown that could not be flown with any class of modern aircraft. The path to understanding this technology would include lightweight batteries, generators, high-power electric motors matched to new quiet rotors and advanced controls for complex, electrically-driven onboard systems. After the NASA competition we started on a fully electric battery-powered Diamond HK-36 dubbed the eSpirit of St. Louis — in honor of Charles Lindbergh’s notion of balance between aviation and the environment. This aircraft serves as a testbed for our students to cut their teeth on the interdisciplinary aspects of mixing electrical engineering into what has most decidedly been an aerospace engineering space. Before moving to funded projects, students learn the basics about electric propulsive motors, motor controls and the specially built electric propellers attached to them.

Eco Eagle at a Glance

100 horsepower Rotax four-cylinder engine 40 horsepower electric motor Uses gas-type propulsion for power-hungry takeoff and landing stages and electric for the longer and less power consuming nature of cruise flight

Hybrid Clutch Assembly A hybrid clutch assembly

inserted between an internal combustion

engine and the propeller of an aircraft to provide a hybrid-powered aircraft.

U.S. PATENT NO. 9,254,922 A

Vehicle Capabilities


Cruise Speed — 55 KTAS Minimum Speed — 0 KTAS in Hover

Electric Motor — 25 min. Endurance Gasoline Motor — 4.75 hr. Endurance Serial Hybrid Motor — 3 hr. Endurance

Autorotation — Capable Lift Capacity — 115 lbs.



Purpose-built Circuit Boards High Fidelity DGPS and INS Plug-and-play Flight Control

9.6 ft. Wingspan Carbon Fiber Airframe

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and autonomy into aircraft conceptual design. While it was our desire to rewrite the books on aircraft design, it was clear we had more work to do on the individual attributes of the enabling technology. We invested in the autonomy of future aircraft with sights set on pilotless aircraft. To that end, we built an unmanned twin- engine tail sitter vehicle that takes off vertically and transitions to fixed-wing flight. The aircraft’s controls were developed via iterative parameter identification; the vehicle essentially learned to fly. A step to achieving full autonomy is simplified vehicle operation (SVO). For SVO, we relied on Flight Level Engineering, a member of the Embry-Riddle Research Park. Flight Level has a strong track record of research on simplified manned aircraft controls using a variable stability airplane that can be reconfigured to mimic the handling qualities of any airplane with operator’s imposed control law. Read more about this area of research on page 21.

Investing in Autonomy Understanding electric motors and

controllers is not the only technology that is required. Understanding the top-level design space is of greatest importance. The design space needed to fold distributed electric propulsion, quiet rotors, lower emissions,

A student adjusts a prop rotor on an electrically powered technology demonstrator, which uses novel control algorithms and propeller mechanisms to transition between hover and normal winged flight.

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Several of our projects merited further investigation when variable pitch rotors and propellers were coupled with high torque electric motors and revealed interesting noise attributes. To that end, we built an anechoic chamber, a space designed to absorb the reflections of sound, to test the noise levels of the new rotors and propellers. Through it we discovered that at constant thrust, RPM could be changed to yield a “sweet spot” where propulsive efficiency is maximized and noise is minimized. This key discovery is of great value for the noise-sensitive UAM market and is part our conceptual design tools. Read more about this area of research on page 24.

Electrification is Key to UAM Industry After an exhaustive exploration of the underlying technologies that may enable greener aviation and UAM, two critical scaling laws appeared to be acting as major barriers. First, the weight of the current batteries would not allow battery-only aircraft to go at the speeds of commercial aircraft. The second is that simple hobby- style fixed rotors could not be scaled up when used for both propulsion and control. There are workarounds for these two barriers but neither is simple. The answer for the heavy weight of batteries is hybrid- electric. This can be a gas engine tied to

Anechoic Chamber Developed in-house, the fully instrumented anechoic chamber is used for validation and verification of computational fluid dynamics- based acoustic studies. In an effort to minimize UAM noise, tests are conducted on the university’s novel prop-rotors.

S E R I A L H Y B R I D The serial hybrid is the

best answer to the age-old aviation problem of heavy batteries. This gas-electric powerplant was developed for a typical air cargo vehicle.

a generator to make the same electrical output as a battery but at a great savings on weight. The solution to the other barrier is to use helicopter rotors with collective and cyclic pitch — both requiring research and development we are currently investing in at Embry-Riddle. Ongoing research projects building hybrid powerplants and UAM- targeted rotor and motors support this need. Our newly developed hybrid powerplant, for instance, promises a ratio of electric power-to-weight that is 4.6 times better than any existing battery system on the market. The technology converts power from an efficient turbocharged engine to

a highly concentrated electrical power, which can then be transferred to eVTOL vehicles. Gasoline feeds into a lightweight, turbocharged aluminum engine, which transfers engine power from the crankshaft into a high performance electric generator. Using this method lowers emissions because the engine and generator are operating at their most efficient settings at all times. Couple that with UAM’s projected lack of traffic or stoplights and we can almost certainly expect a more environmentally friendly solution than traditional surface transportation.

4.6 x Newly Developed Hybrid Powerplant Promises a ratio of electric power-to-weight that is 4.6 times better than any existing battery system on the market.

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Seizing on the global push for more cost- efficient, environmentally responsible and innovative transportation solutions, Embry-Riddle has teamed with private industry and government laboratories to collaborate in precompetitive research of electric and hybrid aircraft. The resulting Hybrid Electric Research Consortium is investigating the electric propulsion design space to find a commercially viable green airplane. The consortium identified two focuses early on. One route is to electrify conventional-looking commuter aircraft, referred to as a thin haul, to reduce dependence of fossil fuels and carbon emissions. The other focus is to use electrification to enable a quiet and extremely reliable replacement for the helicopter to be used as the UAM platform. Multiple patents and successful hybrid and electric aircraft projects are leveraged and shared with the membership as researchers examine classic aerodynamics and new, alternative propulsion systems.

The Eagle Flight Research Center, which is dedicated to applied engineering, develops high quality hardware and measures actual systems through modeling and simulation.

What’s Next?

The technology for commercially viable UAM is available now. We must now overcome the obstacles of integrating existing technologies in a novel way to realize the next generation of quiet, efficient and reliable helicopters.

Electrifying conventional- looking commuter aircraft will provide reduction in emissions, but its commercial realization is critically tied to battery specific energy. It is clear that basic discoveries in battery chemistry are necessary for the goal of high speed commercial aircraft to be fully realized. Our goal at the Eagle Flight Research Center is to advance state-of-the-art in these concepts and make sustainable urban mobility a reality. This will require developing technologies, advanced engineering and design tools as well as a favorable regulatory environment. Here at Embry-Riddle we are working on all of these requirements to bring the third revolution in aircraft propulsion to market.


Argonne National Laboratory Airbus The Boeing Company Evation Honeywell GE Aviation Textron Rolls-Royce Hartzell Cape Air

Distributed electric propulsion is HIGHLIGHT OF NEW AIR VEHICLE

Embry-Riddle’s new personal air vehicle, known as PAV-ER, combines a decade of electrified propulsion progress, innovative control laws and autonomy research into a proof of concept that could propel the future of urban transportation. As more than 250 companies around the world race to become UAM vehicle manufacturers, Embry-Riddle is demonstrating its leadership in the field by building a manned experimental aircraft with distributed electrical propulsion and helicopter rotor blades. For researchers, the PAV-ER project is the next logical step to merge 10 years of technology development with an 8-rotor eVTOL aircraft that employs cyclic propeller pitch for transition between vertical to horizontal flight modes.

A new experimental vehicle built in the university’s aerospace research facility gives students unique experiences in hybrid propulsion and fly-by-wire controls.

By Kelly Pratt

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Each distributed electric propulsion unit uses collective pitch control and cyclic pitch control applied to a hingeless prop-rotor. They have the ability to create thrust, in addition to a combination of thrust and moment control.

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Δ Thrust

Δ Moment


Δ Moment


δ coll

δ long, δ lat

Cyclic Pitch / Thrust Control The ability to create large moments can significantly increase the control authority of a vehicle in both nominal and degraded modes.


“We developed all the underpinnings of UAM technology here and all that was remaining was to merge them into a technology demonstrator vehicle,” said Richard “Pat” Anderson, director of the University’s Eagle Flight Research Center (EFRC), one of the nation’s leading researchers in alternative propulsion. Valuable lessons learned and experiences gained through three previous projects at the EFRC culminated in late 2019 with the development of PAV-ER, a 500-pound technology demonstrator. Almost a decade ago, students and faculty developed the world’s first parallel hybrid aircraft, which spurred the research and development resulting in a fully electric battery-powered aircraft using a Diamond HK-36 airframe in 2016. By 2018 the researchers at EFRC designed and developed the Mark II, an unmanned VTOL tailsitter vehicle that essentially taught itself to fly using novel AI-based control laws. Read more about this area of research on page 5. Working alongside faculty researchers, aerospace and mechanical engineering students are regularly testing the capabilities of PAV-ER’s eight distributed electric propulsion units, which can change thrust by employing three different strategies. Inspired by Mark II’s propulsion system of pods, they successfully demonstrated the scalability of the models on the PAV-ER. The vehicle is able to create thrust, or control, or a combination of thrust and control through its ability to control each hingeless prop-rotor independently or in unison, in addition to its ability to change motor RPM.

“Being able to switch across these three control strategies makes the PAV-ER testbed an invaluable tool in understanding how these types of aerospace vehicles should be certified depending on the thrust, lift, and control strategy used,” Anderson said. Control is possible through the ability to generate longitudinal and lateral moments creating significant control authority in nominal and even degraded situations. Following propulsion simulations in MATLAB and Simulink, researchers developed the fly-by-wire flight control laws for a full vehicle simulation in preparation for the actual flight tests. The student-centered project also gave the future engineers an opportunity to experiment first-hand with initial autonomous flight testing. Most of the research has focused on increasing reliability and the vehicle’s ability to accommodate in-flight failure, such as the loss of a rotor head. “We have been able to demonstrate that PAV-ER’s distributed propulsion architecture and the high control authority of each pod allows the vehicle to continue flight with at least one failed rotor,” Anderson said. “This begins to align with airline-type safety requirements, which makes the vehicle safer than standard helicopters.” Researchers will continue to test and refine flight control algorithms and systems to be used in eVTOL vehicles of the future. Anderson said they plan to share test data results with the aerospace community as well as industry to promote rapid advancement of UAM and to shape the future of airworthiness criteria and means of compliance for these new types of vehicles.

“We developed all the underpinnings of UAM technology here and all that was remaining was to merge them into a technology demonstrator vehicle.”

Transforming the HK-36 into the pioneering all electric aircraft helped researchers develop a better understanding of the electric side of the hybrid propulsion equation.

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Assistant Professor Kyle Collins, Ph.D., reviews the PAV-ER

E A G L E F L I G H T R E S E A R C H C E N T E R The center studies four key areas of aviation technology: propulsion, unmanned autonomous vehicles, manned flight control and certification. This includes projects related to electric and hybrid- electric flights, novel UAVs and unleaded aviation fuels.

urban air mobility vehicle design concept against the prototype taking shape at the Eagle Flight Research Center.

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There are nearly as many market forecasts as there are UAM aircraft programs, and it is often difficult to balance the real market potential with the hype. Working hand in hand with Embry-Riddle experts, VerdeGo Aero is providing essential powertrain hardware and conceptual engineering services for many UAM aircraft. This experience has given the company a unique perspective on the direction the largest emerging market in aerospace is taking. Founded in 2017 by a team of electric flight pioneers, including Erik Lindbergh — the grandson of aviator Charles Lindbergh, who made the first solo transatlantic flight in 1927 — VerdeGo’s roots are in hybrid electric and battery-electric VTOL aircraft with a calling for cleaner and quieter aviation. The biggest new aerospace market segment since 1950s jet air travel is on the verge of taking off.

By Eric Bartsch

Eric Bartsch is chief executive officer and co-founder of VerdeGo Aero, a leading developer of electric powertrain hardware at the Embry-Riddle Research Park. A commercial pilot, his background includes executive roles and experience commercializing new innovations in many industries.

VerdeGo Aero is focusing on the production of electric power that enables missions using distributed propulsion pods.

UAM is defined as the commercial transportation of passengers on very short-range flights of less than 50 miles .

We recognized early on that one of the biggest market needs in electric flight was for reliable, modular, standardized hybrid- electric systems that could enable a wide array of diverse aircraft types. Together with Embry-Riddle’s Eagle Flight Research Center, the company is providing critical and enabling technologies, which will fuel a revolution in electric aircraft design. Attracted by the university’s investment in research and its commitment to building a supportive innovation ecosystem, we became the founding tenant of the new Applied Aviation and Engineering Research Facility at the Embry-Riddle Research Park in February 2020. The location and supportive nature of the neighboring business ventures in the park and in the Florida Space Triangle position us at the center of innovations that are shaping the future of flight. As the technology accelerates toward a new reality, VerdeGo offers a look at the technical and market perspectives for different approaches to UAM aircraft, the forces affecting pricing and the locations where UAM is expected to emerge first. Expect Autonomy for Smaller Aircraft The convergence of electrification, autonomy, noise-mitigation technologies, and mobility as a service has the potential to create as large of an impact on short- range commercial flight as the emergence of the jet engine did in the 1950s for long- range commercial air transportation. UAM, defined as the commercial transportation of passengers on very short-range flights of less than 50 miles, provides a fast and economical alternative to surface transportation in locations where there is significant traffic congestion. Aircraft in development for the commercial UAM market fall into two size categories depending on several operational and

business model factors. The larger UAM aircraft typically carry five to seven people. These aircraft are sized such that the operating economics are viable with a human pilot onboard, and they would primarily be used in route-based operating concepts where there is enough traffic to frequently gather small groups of passengers to fill the aircraft. Meanwhile, smaller UAM aircraft typically sized for two passengers are intended to be autonomous in order to be commercially viable. The weight of the pilot with respect to the useable aircraft payload, and the cost of the pilot, make it prohibitive to have a two seat-piloted commercial aircraft. Smaller aircraft are favored for on-demand route networks where the aircraft can be profitably dispatched with a single passenger between any two points in an urban network of vertiports.

E R I K L I N D B E R G H Executive Chairman of VerdeGo Aero, is the grandson of Charles Lindbergh, who made the world’s first transatlantic flight in 1927. Lindbergh, a commercial pilot, retraced his grandfather’s flight from New York to Paris in 2002. In addition to serving on the board of the XPRIZE Foundation and as board chair of the Lindbergh Foundation, he is focused on making general aviation cleaner and quieter through electric propulsion technology.

Forces Affecting Pricing Both of these operating concepts and aircraft sizes are

viable and likely to co-exist in airline fleets serving major urban markets. However, there is a potential early advantage to the certification of the larger aircraft due to the ability to employ human pilots. Currently the regulatory framework for certifying these new VTOL aircraft under the FAA and Europe’s airworthiness standards is coming into focus and there is significant early interaction between industry groups and regulatory agencies. However, the work related to certifying new aircraft may be moving faster than the ability to certify autonomy for commercial use. The early years of the UAM market will likely be dominated by the larger aircraft under

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Thermal control system

Diesel aviation engine

V E R D E G O A E R O I R O N B I R D This ground-based, operational test bed demonstrates the diesel hybrid electric concept. More than just a generator set, the Iron Bird includes a simulator-driven control station that enables real-time, hardware-in-the-loop testing of realistic mission profiles and use-case scenarios for a variety of vehicles and mission types.

Turbo charger

development, and these will be operated on the higher traffic routes where passengers can be aggregated for regularly scheduled flights. In order for the UAM market to grow rapidly and to a significant size, passenger pricing must be cost-competitive with premium surface transportation options. Black car services typically cost $100 to $150 for longer trips in congested urban areas and can be priced at $4 to $7 per passenger mile, according to major metropolitan area data from Uber and Lyft. This is orders of magnitude higher than the seat-mile cost benchmarks most people are familiar with for conventional commercial airline flights. It is important to benchmark surface transportation and not commercial aviation when understanding the economics of UAM. In this context, it is feasible to develop competitive aircraft that offer competitive cost and significantly higher speeds for premium travel markets such as business travel between high-traffic urban hubs, and between these densely populated locations and international airports.

While a $100 journey is infeasible for most daily commuters, the Global Business Travel Association has found there are hundreds of millions of busy business travelers projected to spend more than $1.6 trillion annually on travel, and who are already expensing local surface trips with a similar cost per mile, while traveling far slower than is possible with an aerial option. Initial market pricing is likely to start significantly above surface transportation options, but as the UAM market grows and the in-service fleet of aircraft increases, the supply of aerial service will grow to meet demand. Once supply and demand are balanced, it is important that the aircraft are designed to support competitive pricing with premium surface transportation in order to ensure the market grows sufficiently large to be worth the investment in the development and certification of new aircraft. As the market continues to mature, and as aircraft designs become increasingly more economical, UAM may grow beyond the premium travel market, but this requires advances in economics that are unlikely to be available in the first or second generation of UAM aircraft.

VerdeGo Aero is focusing on the production of electric power that enables missions using distributed propulsion pods. A new style of propulsion will enable urban air mobility. Both vehicles may seat two to four passengers, plus the pilot.

Electrical conditioning box Changes the electricity from AC to DC for use in the propulsion pods.

Drive shaft Connects the diesel engine to the generators.

Electric generator

Thermal control systems

The premium business travel market segment alone could utilize more than 200,000 aircraft globally. These are gigantic fleets from a conventional aerospace perspective, but they are a modest number of vehicles when approached from an automotive viewpoint. Supply chains for UAM aircraft will look more like McLaren or Ferrari production than Ford or Toyota’s manufacturing. Our research suggests the market will likely require up to $20 billion of annual aircraft production using enabling technologies that are under development now at research institutions such as Embry-Riddle and companies such as VerdeGo. New aircraft designs that leverage the innovations underway in propulsion, efficiency, controls and noise mitigation will enable new types of aircraft to operate as good neighbors from new vertiport locations. The result is the largest new aerospace market segment since the emergence of jet air travel in the 1950s. We are on the verge of a step change in aerial mobility and the

Megacities An Ideal Global Market

UAM is a global phenomenon more akin to commercial airline flight than general aviation. The majority of the largest, most congested cities in the world are outside the U.S., and these are the most desirable early markets. It is important to note that UAM already exists in São Paulo, Brazil with a large fleet of helicopters serving a significant number of urban vertiports. To begin meeting the needs of UAM’s growth, VerdeGo is developing the world’s largest diesel-electric aerospace hybrid system at its facility in the Embry-Riddle Research Park. This system is designed for installations requiring up to1megawatt of power, while using globally available Jet A fuel. Even if the market is limited to just the premium business travel segment, VerdeGo forecasts a fleet of more than 500 aircraft would be necessary to serve the demand in a typical megacity of 10 million-plus people. While this represents a very small fraction of the total travel needs of the city, and it will have a negligible impact on surface travel volumes, it is a huge growth market for aerospace.

“To begin meeting the needs of UAM’s growth, VerdeGo is developing the world’s largest diesel-electric aerospace hybrid system at its facility in the Embry-Riddle Research Park.”

innovation ecosystem built around Embry-Riddle is leading the way.

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to FAA Regulations for UAM Development INFLUENCING KEY REVISIONS

By Kelly Pratt

getting safety-enhancing technologies to the marketplace more quickly. The new rules became effective in 2017 and give manufacturers leeway to employ what are known as consensus standards to meet airworthiness requirements. Part of a global effort to create common standards, the update also helped break down barriers and promote the acceptance of new airplanes and products worldwide, which are key factors in the development of the UAM industry. Professor of Aerospace Engineering Dr. Richard “Pat” Anderson, who Bowles studied under when he was a student, played a vital role in getting the revision effort off the ground. Working with GAMA, where Bowles and other Embry-Riddle alumni were among the leadership team, Anderson organized meetings and conferences that helped create the consensus the FAA was looking for to drive the revision of Part 23. “The rules had been outdated for 30 years,” said Anderson, chair of GAMA’s Electric Propulsion Committee. “It was very prescriptive with means of compliance written directly into federal law. It was essentially a guide on how to build an aluminum airplane.”

A surge in UAM innovation and the development of new aircraft propulsion systems are more possible today thanks to revised FAA standards that went through much of their formative stages at forums and meetings hosted by Embry-Riddle. Those sessions, which began almost a decade ago, brought together some of the top minds and authorities in aviation to help change outdated standards that many believed were stifling innovation. “Before anyone had begun to formally grapple with a solution, the team at Embry-Riddle was hosting these sessions, and it showed a lot of foresight that the university ensured it was part of the petri dish,” said Greg Bowles, a 1998 Aerospace Engineering graduate who helped organize stakeholders during his time as vice president for global innovation and policy for General Aviation Manufacturers Association (GAMA). “It really was one of the cornerstone locations for all of this to begin.” Driven by Congress’ Small Airplane Revitalization Act of 2013, updating the FAA’s Code of Federal Aviation Regulations required overhauling its Part 23 airworthiness standards for general aviation airplanes weighing less than 19,000 pounds with 19 or fewer seats, with an eye toward

Greg Bowles

“It was very prescriptive with

means of compliance written directly into federal law. It was essentially a guide on how to build an aluminum airplane.” — Anderson

Building something as unique as a flying taxi or a personal air vehicle and bringing it to market wouldn’t have been possible until the overhaul. Thanks to private industry’s efforts to work hand-in-hand with the FAA, Part 23 went from 277 rules down to 74 rules in addition to new means of compliance contained in consensus standards that groups like GAMA helped create. Changing longstanding federal rules takes time, effort and a dedicated group working toward the same goal. That’s why it made sense for Embry-Riddle to be directly involved with GAMA as a host, idea incubator and consensus builder for aviation manufacturers and owner operators from all over the world. “It’s the perfect setting,” said Anderson, who leads the university’s aerospace research and design facility, known as the Eagle Flight Research Center. “GAMA is engineering plus aviation and Embry-Riddle is engineering plus aviation.” A member of GAMA since 2016, the university continues to be the only

As head of the GAMA initiative designed to address Part 23, Bowles took the lead at GAMA while countless others across industry also worked with the FAA. “Being able to sit down with people from all over the world in a collaborative aviation environment like Embry-Riddle no doubt added to our success,” he said. With Embry-Riddle on the leading edge of UAM and new technologies such as hybrid electric propulsion, helping change older standards is key to pioneering future aircraft, Anderson said. The speed in certification is essential to bring new aircraft to market. “This allows significantly more innovation because you don’t have to change the rules to do something novel,” Anderson said. As hundreds of UAM companies worldwide continue to push technology to new heights, the work with the FAA is expected to be ongoing. New standards for electric propulsion, structures and materials are being adapted and written regularly to respond to evolving technologies, said Bowles, who transitioned from GAMA to join Joby Aviation in late 2019. Now head of governmental affairs role at Joby, Bowles said the UAM startup’s first vehicle is currently being certified by the FAA with a 2023 target date set for commercial service. Looking back at his time at Embry-Riddle, Bowles said he is grateful for the contribution his former professor and alma mater have made to opening the door for innovative new aircraft and propulsion development. “The flexibility in the new rules create a really optimum environment. We would be at a standstill without it,” Bowles said. “This is more exciting than I thought this could ever be. The things that my children will be able to do in aviation are going to be amazing.”



academic member of the organization — a testament of

its leadership in technology and in the regulatory environment for certification, said Christine DeJong, the current director of global innovation and policy at GAMA. “The relationship also gives the university an opportunity to present its research to industry while giving faculty insights into the types of skills the upcoming workforce will require.”

R E D U C T I O N Part 23 was reduced from 277 rules to 74. Many details transitioned to new standards, which are being updated regularly.

Embry-Riddle Writer Jon O’Neill contributed to this report. Image Credit: Joby Aviation

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A test pilot flies a one-of-a-kind Ryan Navion equipped with Simplified Vehicle Operations (SVO) controls, which enable the aircraft to take on the flying characteristics of a future UAM vehicle. The controls platform, known as EZ-FLY, allows Flight Level Engineering to research how untrained pilots would perform with simplified controls in an effort to reduce training time.

Dr. Martos is an aerospace engineer and research pilot for the Embry-Riddle Eagle Flight Research Center. He is an expert in 5 and 6 degrees of freedom in-flight simulators, specializing in flight dynamics and control for aerospace vehicles. A graduate of Embry-Riddle, Martos is a commercial pilot, president and co-owner of Flight Level Engineering, an aerospace research firm focusing on SVO demonstrations and government certification.


Looking at just the commercial viability of vehicle production, Uber Elevate estimates the need for at least 5,000 VTOL units per year, according to its 2016 white paper study. Well before we will ever see a fully autonomous flying car, the new industry will initially need to tap into the fixed-wing pilot pool to command eVOTL and eSTOVL vehicles. Accommodating the fixed-wing pilot requires simplifying operations and making sure controls and other human machine interfaces operate similarly to what fixed-wing pilots are accustomed to. They must also demonstrate a path to autonomous operations. At Flight Level Engineering we are making inroads in this area through SVO and Simplified Handling Qualities (SHQ) on our EZ-FLY platform. A member of the Embry-Riddle Research Park, Flight Level has refined the advanced flight control augmentation system so that even a non- trained pilot could potentially fly. Eventually an aerial vehicle would likely require a manager or operator with an endorsement, rather than a traditional licensed pilot. With a control scheme engineered to be agnostic of the aircraft configuration, a fixed-wing pilot may transition to become an operator of highly augmented or semi-autonomous STOVL or VTOL aircraft with significantly reduced training requirements.

As a result of advances in avionics and flight control systems, as well as increased safety and reliability, the road is now paved for the highly automated commercial flight vehicles for the UAM industry. While flying cars are closer to reality — Uber has aerial ridesharing plans for 2023 — the pilot pipeline needed to support this emerging industry needs to keep up with the potential demand. The global pilot shortage statistics speak for themselves. The 2019 Boeing Pilot & Technician Outlook projects 804,000 new civil aviation pilots will be needed worldwide over the next 20 years, or about 40,000 new pilots every year. The potential shortage also applies to helicopter pilots, with a forecast of about 61,000 over the same period or about 3,000 each year. For comparison, in the United States alone, the FAA issued only 2,300 new rotorcraft licenses and 18,000 commercial and airline transport licenses in 2018. Helicopter and powered lift pilots (the few who operate the military’s Harrier, Bell Boeing V-22 Osprey or Lockheed Martin F-35) will be in highest demand as they are best skilled to operate eVTOL and electric short takeoff and vertical landing vehicles (eSTOVL). Yet with the demand so high in the already established commercial aviation market, one can almost certainly expect a shrinking pool as airlines also aggressively recruit them.

The pilot shortage could impede urban air mobility (UAM) from taking off unless autonomy becomes more synonymous with the industry.

By Borja Martos, Ph.D.

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Michelle Yeh and Kelene Fercho, engineering research psychologists with the FAA, listen in on the EZ-FLY simulation platform demonstration during the Fly-By-Wire Summit in March 2020.

Initially created for NASA’s Advanced General Aviation Transport Experiment (AGATE) program some 20 years ago, EZ- FLY serves as a testbed for proof of concept of SVO. The use of automation and human factors best practices used in our EZ-FLY platform reduces the amount of skills and knowledge a pilot or aircraft operator needs to operate within safety requirements. Our researchers are demonstrating its capabilities through experimental aircraft, ground-based cockpit simulation, and desktop control stick and display simulation. Together with Noel Duerksen, who previously led EZ-FLY development on NASA’s AGATE program, we also programmed EZ-FLY for STOVL and VTOL aerospace vehicles. The system was on display during the March 2020 Fly-By- Wire Summit, where industry professionals gathered in Daytona Beach, Fla. An avionics software engineer and an electrical engineer, both Embry-Riddle alumni, demonstrated EZ-FLY in-flight simulations aboard a Ryan Navion, a piston engine aircraft originally

A certification representative from the FAA experiences an EZ-FLY platform demonstration at the Fly-By-Wire Summit.

built as a variable-stability platform to train test pilots and flight test engineers. Our success with EZ-FLY is just the start, however. As more highly automated aircraft are developed, the training paradigm will have to evolve to meet the UAM industry’s growth. In an effort to advance this area, Flight Level is working with the FAA and NASA on certification proposals and demonstration of highly augmented aircraft with simplified licensing requirements and operational procedures. The transition to more autonomous operations will be gradual. Fixed-wing pilots will likely be at the controls of highly augmented or semi-autonomous aircraft, not only to meet future FAA certification standards, but also to satisfy evolving public opinion.

“The use of automation and human factors best practices used in our EZ-FLY platform reduces the amount of skills and knowledge a pilot or aircraft operator needs to operate within safety requirements.”


Alum Joins ‘Transportation Revolution’

Grad Puts Theory to Work

For Alfonso Noriega (’11, ’16) the agile and hands-on environment at startups give him the ability to break new ground in dynamics and controls engineering.

At Bell, Donovan Curry (’10, ’13) is part of a team pushing the limits of technology to reimagine the future of transportation and autonomous flight.

“Everything we are working on now — from the avionics, the flight controls, the control law, autonomous navigation, to the battery and electric motor technology — will be used to set the foundation for a transportation revolution,” he said. As an engineer specializing in control law development, Curry is part of an innovation group conducting R&D for military and commercial projects, such as the Bell Nexus air taxi and the Autonomous Pod Transport. While most of his experience prior to joining Bell in 2019 involved larger business aircraft for Cessna and Gulfstream Aerospace — Curry found his work in static loads, flight dynamics, and control laws easily complements Bell’s specialty. “The key to making UAM energy efficient is to design a VTOL that flies an aircraft in forward flight,” he said. “I think my background in airplane control law design and Bell’s history of helicopter design match well in bringing the two philosophies together.” A native of the Bahamas, Curry’s passion for aviation began with plane spotting from his grandparents’ home located near the final approach at the Lynden Pindling International Airport. Early interactions with pilots and crew as an airline intern introduced him to aerodynamics and controls. At Embry-Riddle, Curry went on to earn his bachelor’s degree in Aerospace Engineering and master’s in Mechanical Engineering. The theories he learned in class were applied at the Eagle Flight Research Center, where among memorable projects, a team designed a control law algorithm for a RC SkyWalker. It was his first introduction to drone work and developing an autopilot system using a microprocessor. “There were hardware limitations and we burned out a few boards with bad wiring,” he recalled. “But sometimes the simpler ideas worked best. The airplane did eventually fly and navigate to waypoints, but there were hard lessons to learn, lots of compromises and lots of iterations.” Now on the cusp of helping UAM become a reality, those early design lessons still ring true today in real-world applications, he said.

“It’s extremely satisfying knowing that you’re solving problems that haven’t been solved before. Watching an aircraft take off autonomously, fly around, and come back with code that we programmed is very rewarding,” he said, recalling his time at Acubed, an Airbus venture that produced Vahana, a self-piloted electric UAM technology demonstrator vehicle in Sunnyvale, Calif. Noriega — the university’s first Aerospace Engineering Ph.D. graduate — gained experience in this type of bold testing environment at the Embry-Riddle Eagle Flight Research Center. By the time he completed his doctorate degree, he had instrumented a Cessna 182 with sensors and a computer that allowed him to tap into the aircraft’s autopilot and feed it guidance commands to essentially “fly itself.” For his first job out of college — under the wing of two alumni who own Flight Level Engineering — Noriega wrote flight control software for a rare Ryan Navion, a variable response aircraft that exposes pilots and engineers to different flying characteristics and control systems. Now working as a guidance, navigation, and controls engineer at Archer, a UAM startup, he is part of a team developing an eVTOL. The Palo Alto-based company aims to provide a sustainable and safe alternative to traditional surface transportation. Since joining in January 2020, Noriega, who is also a private pilot, has participated in developing Archer’s flight control system and is involved in testing and feedback discussions related to its design. Embarking into a new technology sector means there isn’t always a blueprint for a way forward, Noriega said. But that’s where a problem-solver mindset and the engineering basics he learned at Embry-Riddle continue to serve him well. “If you know how the theory works, you can apply it to make something fly in a different way. I think that’s the key when you’re trying to build something that doesn’t exist yet,” he said.

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NOISE REMAINS A TOP CHALLENGE for Making Air Taxis a Reality

ensure blades are designed to promote low noise instead of using existing helicopter blades. For multi-rotors, the aerodynamic interactions are essential because they alter the aerodynamic loads and contribute to broadband noise as well as create additional blade vortex interactions. Multi-rotors offer different possibilities to lower the noise, e.g., rotation direction and phasing strategies for quad-rotors have shown that some decent noise reduction can be achieved. However, the variability of the different configurations complicates the noise issue. Also, the possibility of several different UAM vehicles operating at the same vertiport is an important issue and contributes to broadband noise. Finally, the effect of the environment (e.g., urban canyons) has to be included in the studies. It is estimated that we need to get to a 15 dB reduction compared to a helicopter of the same weight class to reduce noise to the level of automobile traffic. In order to achieve significant noise reduction, noise must be accounted for in preliminary/conceptual design as well as operation parameters. It is also unclear if new FAA noise certification regulations will be needed, and if they are, significant delays should be expected.

Uber recently announced it will be launching UAM service for key cities in 2023. Is this timeline for aerial taxis realistic? Let’s go back in history. In 1943, a LIFE Magazine writer proclaimed that “After the war is over… the helicopter may well become the average man’s flying machine to be used — not right away but inevitably — much as the average man uses his automobile.” The cover photo featured aviation pioneer Igor Sikorski with an early helicopter followed by illustrations of a post-war commuter leaving his home via helicopter for a day in the office. Seventy-seven years later why has this prediction not yet been realized? There are several reasons — chief among them: the helicopter still faces safety concerns and it is not easy to control compared with the automobile. Rotor noise also remains a persistent problem. Rotor noise (when tip Mach numbers are below the transonic value) can be divided into thickness noise (due to the fluid displacement by the rotor blade), loading noise (due to the rotating of the blade forcing lift and drag), blade-vortex interaction (due to the blade interacting with the tip vortex of the preceding blade), and broadband noise (due to ingestion of atmospheric turbulence, interactions with rotor wake turbulence, and scattering of turbulence over the trailing edge). UAM vehicles have lower Mach numbers and Reynolds numbers compared to a regular helicopter resulting in higher amounts of loading noise and, most importantly, broadband noise. That’s why it is crucial to

By Tasos Lyrintzis, Ph.D.

Dr. Lyrintzis is a distinguished professor and chair of the Aerospace Engineering Department at Embry-Riddle. He is an AIAA Associate Fellow, an ASME Fellow, and a Boeing Welliver Fellow. 15 dB reduction

It will certainly take time and patience to resolve the many important noise issues before UAM vehicles achieve industry commercialization. Significant investment is needed to support research and development in this area.

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