As battery makers worldwide strive to develop safe, high-energy-density cells, Breezer Aircraft, a German small-aircraft manufacturer, unveils plans to power one of its ultralights with a hydrogen fuel cell.
Breezer’s B400-6, receiving 600kilogram certification by the DAeC (German Aero Club), is light enough to enable a small fuel-cell-motor combination to power it. Usually powered by the ubiquitous Rotax range of engine, an electric version will initially to be driven by batteries, and then powered by a hydrogen-fuel cell.
Presentation of the project idea at Lüneburg airfield. The metal construction allows both enough space and a compact installation of an electric drive train, the energy of which is to be obtained from fuel cells. Owner Dirk Ketelsen also operates his own wind farm. which will also produce hydrogen from electricity in the future . There is hardly a better way to use wind energy. Photo and caption from http://www.electric-flight.eu/
eCap and Re-Fire
eCap, a German company specializing in systems integration and installation for a diverse range of classic and modern vehicles, will work with Breezer on the first installations. eCap’s demonstrated ability to convert everything from an antique farm tractor and classic cars (including a DeLorean) to modern buses and delivery trucks shows their range.
2015 sampling of vehicles converted by eCap
Employing state-of-the-art technology and techniques such as reverse engineering leads to 3D CAD models from which ECap develops prototypes. Perhaps most important, “eCap works completely independently of exclusive suppliers in the development of subsystems and complete systems. This means that we select and combine the ideal components from a large selection of suppliers and products for all aspects of electromobility in accordance with performance requirements and budgets.” They work with prototypes, pilot production and small series operations.
Re-Fire 46kW (62 hp) unit. You still need a motor to drive that big fan in the nose
It weighs 160 kilograms (353 pounds), can fire up at temperatures above -15° Centigrade (5° Farenheit), and run at up to 56-percent efficiency for up to 12,000 hours. It can endure IP67 standards punishment, with complete protection from dust intrusion and the ability to be immersed in water to a depth of one meter (3.28 feet) for up to 30 minutes. All this comes in a 926 millimeter (36.45 inch) x 550 mm (21.65 inch) x 408 mm (16.06 inch) package.
Dirk Lehmann, founder of eCap, sees a potential market for his company’s expertise. “For the coming years , we expect a growing need for reliable, safe and environmentally friendly propulsion and conversion solutions for aircraft.” Although the drive trains will also be offered to other manufacturers, Dirk Ketelsen, managing director of Breezer Aircraft thinks the systems are still too expensive for wide-spread adoption.
We lag behind nature in many areas, and constantly need to remind ourselves of our relative ignorance of her many secrets. Feathers are a case in point, and Stanford University researchers found that, unable to duplicate the nature of these lightest of airborne structures, they needed to use the real thing in their latest drone.
The IEEE Spectrum reports, “The few attempts at making artificial feathers that we’ve seen in the past have been sufficient for a few specific purposes but haven’t really come close to emulating the capabilities that real feathers bestow on the wings of birds. So a century later, we’re still doing the rigid wings with discrete flappy bits, while birds (one has to assume) continue to judge us for our poor choices.”
A Feathery Primer
Before looking at Stanford University’s Pigeonbot, we will indulge a few minutes learning how complex a seemingly simple feather really is.
Those wishing to delve deeper can turn to a marvelous book by Thor Hanson, Feathers, The Evolution of a Natural Miracle. Hanson recounts the evolution and biology of feathers and tosses in compelling anecdotes. One such explains that the most expensive things lost in the sinking of the Titanic (aside from the 1,200 lives) were $400,000 (millions now) in mainly ostrich feathers bound for New York milliners – part of the feather craze in fashion then.
Unable to duplicate those characteristics and complexity, researchers at Stanford University had to find another way to plume their robotic pigeon. David Lentink, assistant professor of mechanical engineering and head of Stanford’s Bio-Inspired Research & Design (BIRD) Lab, explains the difficulties. “Feathers aren’t just more complicated to manufacture, but you have to find some way of replicating and managing all of the complex feather-on-feather interactions that govern wing morphing in real birds. For example, by examining real feathers, the researchers discovered that adjacent feathers stick to each other to resist sliding in one direction only using micron-scale features that researchers describe as ‘directional Velcro,’ something ‘new to science and technology.’ Real feathers can slide to allow the wing to morph, but past a certain point, the directional Velcro engages to keep gaps from developing in the wing surface. There are additional practical advantages, too: ‘they are softer, lighter, more robust, and easier to get back into shape after a crash by simply preening ruffled feathers between one’s fingers.’
While feathers themselves may be irreproducible, Lentink’s student researchers discovered that “birds maintain control by morphing the shape of their wings,” which turned to be relatively simple to imitate. The student-made PigeonBot uses a pair of “biohybrid morphing wings” with mechanical undergirding and real feathers.
Morphing consists of movements about two joints on the bird’s wings corresponding to the wrist and finger joints on a human. Lentink found that simply movements of the finger joints could induce rolling, “and that this technique is inherently much more stable than the aileron roll used by conventional aircraft.”
With the real feathers elastically connected to a pair of robotic bird wings with wrist and finger joints that can be actuated individually, PigeonBot relies on its biohybrid systems for maneuvering. Image: Lentink Lab/Stanford University
“The other cool thing we found is that the morphing wing asymmetry results automatically in a steady roll angle. In contrast aircraft aileron left-right asymmetry results in a roll rate, which the pilot or autopilot then has to stop to achieve a steady roll angle. Controlling a banked turn via roll angle is much simpler than via roll rate. We think it may enable birds to fly more stably in turbulence, because wing asymmetry corresponds to an equilibrium angle that the wings automatically converge to. If you are flying in turbulence and have to control the robot or airplane attitude via roll rate in response to many stochastic perturbations, roll angle has to be actively adjusted continuously without any helpful passive dynamics of the wing. Although this finding requires more research and testing, it shows how aerospace engineers can find inspiration to think outside of the box by studying how birds fly”.
Researchers are not patenting their discoveries, having “decided … to help proliferate our discovery to the benefit of society at large” in the hopes that anyone who makes a huge pile of money off of it will (among other things) invest in bird conservation in gratitude.”
In future, Lentink wants to add a biohybrid morphing tail, legs with grasping feet, and additional actuators. Perhaps he can find a way to do away with the un-bird-like propeller, a giveaway that might not impress other avian creatures.
A Wind Tunnel for Birds
David Lentink in Stanford wind tunnel for birds and drones
Your editor has asked for years if batteries in electrically-powered aircraft could be augmented by supercapacitors, devices able to unleash significant amounts of power quickly. The usual answer is that the added weight of supercaps that could add power on demand would be about that of added batteries to equal the performance.
In an explanation and comparison of lithium batteries and supercaps, Matt Ferrell gives a reasonable overview of the two and how they will probably evolve in the future. As he notes, Tesla recently purchased Maxwell technologies, possibly to fill what Maxwell describes as the “energy gap for fast-response, high power delivery solutions.”
Lamborghini and MIT Double the Energy Density in Supercapacitors
Design News reports that MIT and Lamborghini, having partnered on developing advanced supercapacitors for the last two years, recently announced a patented technique for doubling the energy density of capacitors. The advance, “synthesized by professor Mircea Dincă’s team in the laboratories of MIT’s Chemistry Department with the support of Lamborghini’s Concept Development Department, is based on… the “Metal-Organic Frameworks” (MOF) concept.” Maurizio Reggiani directs the Lamborghini department.
According to Design News, “The molecular structure of this family of materials makes it the ideal candidate for producing electrodes for high performance supercapacitors of the future, because it maximizes the amount of surface area exposed to electric charge in relation to the mass and volume of the sample.”
Reggiani (left) and Dincă (right). Image source: Automobili Lamborghini
Great in a Great Car – Will They Work in Econoboxes?
Because the super materials are not yet in a supercar, questions arise whether the MOFs can be made in commercial quantities at a price that dips below the $3.7 million, cost-is-no-object heights of the Lamborghini Sián’s components. Its drivetrain features a naturally-aspirated, 785-horsepower V-12 engine, with a 34-horsepower, 48-Volt motor “incorporated into the gearbox to provide immediate response and improved performance.” An extra 4.3-percent power may not seem like much of a kick in the pants, but does provide acceleration while reducing the load on the engine. Not pushing the engine past its 8,500 rpm redline is a welcome longevity enhancement for a pricey investment. Supercaps are immediately responsive, not requiring the spool-up time of a turbocharger.
Able to sell all the supercars it can build, Lamborghini is probably not concerned about the realities bean counters in more plebeian companies impose. Reggiani says, “Costs have not been evaluated yet.”
GreenCarCongress.com notes the Sián energy storage is three times more powerful than a battery of the same weight and three times lighter than a battery producing the same power. The article adds, “The electric system with the supercapacitor and e-motor weighs only 34 kg, thus it delivers a remarkable weight-to-power ratio of 1.0 kg/hp. Symmetric power flow ensures the same efficiency in both charging and discharging cycles—the most lightweight and efficient hybrid solution.” Considering the system is self-contained and recharged every time the driver pumps the brake pedal, it seems a reasonable boast for the essentially mild hybrid setup.
Reggiani explains why Lamborghini pursues this line. “There’re several very interesting characteristics. The power density, first of all, which makes the capacitors much more powerful compared with batteries — up to three times more power for a given mass — with a symmetrical behavior which makes them able to recuperate as much power as they can deliver. Under this aspect, the difference with batteries is huge.”
Hidden by this cover is the Sián’s super capacitor. Image source: Automobili Lamborghini
Reggiani sees other benefits. “Then, the very low electrical resistance, which means high efficiency and low heat dissipation, and the very long life, measurable in millions of cycles in comparison with the thousands of cycles of the batteries.”
As supercapacitors and batteries increase in power and energy storage capabilities, one wonders if coming changes will change the preferences designers have for their applications. Since academia and industry are progressing on both fronts, we anticipate great things to come – regardless.
eHang has been busy over the past year, with demonstration flights worldwide, and last week in Kitty Hawk, North Carolina – the birthplace of aviation.
Not a Long Commute
In March, 2019, EHang founder, Mr. Hu Huazhi commuted via EHang AAV (Autonomous Aerial Vehicle) in Guangzhou, China. As you can clearly see, it’s not a long commute, but a demonstration of the faith the founder and others have in the machine. As reported here two years ago, the company flew its entire executive group and and Guangshou city officials in their two-seat machines. eHang reports on their extensive testing and demonstration flights: “To date, EHang has safely conducted over two thousand trial flights in the United States, China, Austria, the Netherlands, Qatar, and the UAE to ensure that its AAVs operate safely and reliably in different areas globally.”
eHang, already prosperous from model drone sales, has invested heavily in a corporate infrastructure and international marketing. They note a Blue Paper from Morgan Stanley Research that projects an “addressable market” of $1.5 trillion for autonomous aircraft by 2040. “With the core concepts of autopilot, full redundancy safety design and cluster management by intelligent command and control center, pilots are no longer necessary for a flight, while passengers only need to click the ‘take-off’ button to fly to the selected destination. EHang will provide every passenger a truly enjoyable journey by the safe and intelligent autopilot system. In February, 2018, EHang has unveiled footage of the latest test flights of EHang AAV in Guangzhou, China. Since then, EHang AAV conducted an array of flight demonstrations in Amsterdam, Doha, Vienna. EHang is a world’s leading autonomous aerial vehicle (AAV) technology platform company based in Guangzhou, China.”
eHang’s First Certified Flight at the Birthplace of Aviation
This represents the first time that the EHang 216 has received flight approval from the Federal Aviation Administration (FAA). While this was a non-passenger flight, EHang is working with the FAA to secure approval for a passenger trial flight of the EHang 216 in the near future.
“Our mission is to make safe, autonomous, and eco-friendly air mobility accessible to everyone and this trial flight represents a significant step towards bringing our urban air mobility solutions to the U.S. market,” said EHang founder, chairman, and CEO Huazhi Hu. “Pilotless air taxis have the power to transform everyday life in urban areas since they can lessen pollution, expedite emergency services, and save individuals and businesses time and money through shorter travel times.”
Roy Cooper, the North Carolina Governor, said, “We are proud to have the first autonomous aerial vehicle flying in North America, in North Carolina. Obviously, they are beginning this all of the world and this technology and what it means for transportation, both cargo and passengers, is pretty astronomical. This gonna be very positive for the economy. We want North Carolina to be on the cutting edge of this technology and we’re proud to have EHang here to show and demonstrate to us what can be done with this technology. It’s taking off. We North Carolina has become the pilot that can help move this kind of business forward. We are excited about that.”
To date, eHang has safely conducted over two thousand trial flights in the United States, China, Austria, the Netherlands, Qatar, and the UAE to ensure that its AAVs operate safely and reliably in different areas globally.
Your editor selected this video because it has actual rotor sounds instead of a music soundtrack. There’s no telling how much the sound is modulated.
An eHang Overview
EHang has already delivered 38 units to customers as of December 5, 2019, putting it ahead of the pack with demonstrably capable machines while others display larger concept vehicles.
eHang 216 fly formation over home city of Guangzhou, China
Before its debut flight in the U.S., two EHang 216 AAVs completed simultaneous trial flights of their commercial sightseeing applications in Guangzhou, China on November 30, 2019. Guangzho will be eHang’s first urban air mobility pilot city, with trial flights demonstrating the AAV’s ability to use a variety of landing platforms.
ADDED January 15, 2020
This came out just three hours ago, and is redundant in some places, but includes a stopped propeller demonstration that is fairly compelling.
Delivery Drones with DHL
Showing they still have links to the smaller drone market, eHang has signed agreements with DHL to fly packages along an eight-kilometer (five mile) route between a customer site and DHL’s service center in Liaobu, Dongguan, Guangdong Province. EHang’s new Falcon series will reduce one-way delivery time from 40 ground minutes to only eight minutes, with cost savings of up to 80 percent per delivery.
eHang certainly seems driven to explore new ways to use their technology. With an ongoing program of showing those capabilities to the world, they will probably surprise us many more times.
Two electric Vertical Take Off and Landing (eVTOL) craft captured spectators’ attention at the 2020 CES (Consumer Electronics Show) in Las Vegas, Nevada. Mick Akers of the Review-Journal reported on Bell’s Nexus 4EX, an updated prototype or the concept machine they showed last year, and the New Hyundai SA-1, unveiled as part of its partnership with Uber.
The Bell Nexus 4EX
Akers reports, “After lighting up CES 2019 with its Nexus vertical takeoff and landing aircraft model, Bell returned this year with an updated prototype: the Nexus 4EX.”
Unlike last year’s hybrid version, the 4EX will be fully electric. Akers noted that, “the 4EX features four fan ducts, a reduction from the six shown with last year’s model.”
Bell promotes the benefit more marketers in the UAM segment are attacking – time. “Your commute, transformed. Turn a 45-minute drive into a 10-minute flight. The safe, convenient Air Taxi is designed to let you make the most of your commute. Its sleek cabin offers a comfortable space for you to relax. Or work. Or socialize. All while saving your most precious resource: time.” If you have a pressing need to fly at 150 mph within a 60-mile radius, the Nexus will get you there quickly.
Akers added, “Bell brought along mini drone versions of the Nexus 4EX model and flew them around a miniature city to display how the system would work.”
Mitch Synder, CEO and president of Bell, explains the more expansive plans that “system” would entail. “With focus on the passenger experience, we revealed the technology and the vehicle that will revolutionize transportation in cities at CES 2019. This year we’re demonstrating what governing, operating, working and living in a smart city will look like.”
Smart aircraft and cities will require smart software, so Bell is partnering with Microsoft Azure on which the Bell AerOS system will run. According to Akers, “The service was created to manage fleet information, observe aircraft health and manage throughput of goods, product and predictive data and maintenance.”
Doubling down on Bell’s four rotors (appropriate in Las Vegas), Hyundai’s SA-1 features four tilt rotors and four lift rotors.
Duplicating Bell’s payload with four passengers and a pilot, the SA-1 is a largish 35 feet long, with its 7,000 pound gross weight carried not just on eight rotors, but wing of almost 50 feet.
Close to the Bell’s performance, the SA-1 cruises at 150 mph, with a top cruising speed of 180 mph possible. 100 percent-electric, the sky taxi can fly 63 miles. Most craft designed within Uber’s parameters will have similar performance.
Recently recruited after a 30-year career with NASA, Jaiwon Shin, executive vice president and head of Hyundai’s Urban Mobility Division, says, “Our vision of Urban Air Mobility will transform the concept of urban transportation. We expect UAM to vitalize urban communities and provide more quality time to people.”
Headlined, “Urban Air Mobility Dominates Headlines at CES 2020,” the organization explains that as a followup to its Nexus vehicles from 2019 and 2020, Bell showed off AerOS. They describe is as,“A digital fleet management mobility platform designed to assist eVTOL operators and cities with the complicated task of integrating UAM into the ‘vertical landscape’ over metropolitan areas.”
In a Bell Nexus City display, scale models of the 4EX and their autonomous pod transport cargo delivery vehicle lifted off and landed on rooftops as they would in reality, managed by the AerOS platform.
Hyundai’s approach is a bit more integrated. Their “smart mobility solution” includes the Hub, linking the S-A1 and other UAM aircraft to Hyundai’s Purpose-Built Vehicle (PBV), an autonomous ground transporter offering customized onboard dining, retail or medical service options. The Hub, a modular system, provides docking not only for the aircraft, but for many types of PBVs that seem to be possible.
Linked to the hub, a variety of PBVs would haul people or cargo and even charge the other vehicles.
“Hyundai is our first vehicle partner with experience of manufacturing passenger cars on a global scale,” said Uber Elevate’s Eric Allison. “Combining Hyundai’s manufacturing muscle with Uber’s technology platform represents a giant leap forward for launching a vibrant air taxi network in the coming years.”
Uber had presented three design concepts to manufacturers for aerial vehicles which would suit its Elevate program. Bell, Hyundai, and five others are working on delivering these vehicles so Uber Air can fly them commercially in Los Angeles, Dallas and Melbourne, Australia by 2023.
Uber has been flying conventional helicopters in New York City as a demonstration of how the program would work. According to the NBAA, “The service would be carried out by creating skyports, which would be placed in high volume areas of cities, where up to 1,000 landings per hour could occur, according to Uber Elevate’s website.” See also the White Paper Uber released in 2016 on its anticipated part in urban mobility.
Yolanka Wulff, Co Executive Director at Community Air Mobility Initiative (CAMI), echos this idea.”Urban air mobility will have to be properly integrated into existing and future metro, bus, and other transit options for the full-trip time savings of taking to the air to be realized.” CAMI is working with state and local jurisdictions to solve these issues.
More to Come
This blog will cover more of the ground-based support systems for the potential UAM boom. Report on two architects who designed Uber Elevate Skyports, a realtor who has developed an exurban neighborhood that would be friendly to fixed or rotary-winged aircraft, we will look at the potential for longer-range UAMs to support a different way to commute.
Bye Aerospace has been making inroads into both battery development and flight training with partners on an international scale.
Alliance with Oxis Energy
As reported in July, Bye Aerospace and OXIS Energy announced a collaborative program to achieve a 50-to 100-percent increase in flight time from a single charge compared to existing batteries. On its web site, OXIS reveals that it is, “…developing a <30 kWh battery system integrated with an Aviation Battery Management System for a two-seater electric passenger aircraft.” The partnership, “…seeks to achieve a 50% to 100% increase in flight time from a single charge on future Bye Aerospace eAircraft,” with cells exceeding 500 Watt-hours per kilogram at 20 Amp-hour capacity. This will lead to weight reduction and increased flight duration.
Quantum Air, OSM and Bye Form a Synergistic Enterprise
Quantum Air is a short-range carrier with a mission. “Our mission is simple and prevalent throughout our brands. To change the way people travel through cutting-edge aeronautics, made available to the general public in a cleaner, safer, and more exhilarating way than ever before. We invite a future where on-demand air travel is as ubiquitous as car service, a future where our aircrafts consume half the fuel but generate twice the excitement, a future where you don’t have to go through 2+ hours of travel, check-in, and security for a 45-minute flight.
Quantum relies on OSM Aviation, a 6,000 person operation that has trained pilots since 1963, to provide training for its pilots. Both will use eFlyer all-electric aircraft, and have ordered a total of “160 zero-emission aircraft with significantly lower noise pollution and enhanced altitude performance” to be delivered by the end of 2021.
OSM will train future pilots who will fly the Bye eFlyer 4 for Quantum Air. Like the eFlyer 2, it will have Rolls-Royce power
Tony Thompson, founder and CEO of Quantum, sees the benefits of this approach. “Quantum’s partnership with OSM means that Quantum pilots will fly commercially in essentially the same aircraft in which they trained. Quantum commercial pilots will be intimately familiar with their aircraft, setting a new standard for safety.”
Espen Høiby, CEO of OSM Aviation Group, adds, “Air travel is instrumental in bringing people together both regionally and internationally. Since humans will always have the urge to explore this world, we need to find sustainable solutions to meet that need. Therefore, OSM Aviation is excited to join forces with Quantum Air to shape a greener and safer aviation industry in the years to come.” OSM operates training operations in Norway, Sweden and the United States of America.
Scott Akina, Quantum’s Vice President and Chief Pilot, agrees, explaining, “I expect to receive pilots from OSM who will already know Quantum’s aircraft systems inside and out, and this will be no small part of the reason why Quantum will run the safest operation in the airline industry.”
George Bye, CEO of Bye Aerospace, said he is impressed with the collaborative partnership between OSM and Quantum. “Electric aviation, including our eFlyer family of electric aircraft, is the springboard for a movement that we believe will breathe new life into the aviation industry,” he said. “That includes implementing creative ways to improve effective, economic access to pilot training. The OSM-Quantum model, which focuses foremost on new professional pilot training safety, aligns perfectly with Bye Aerospace’s principles.”
Quantum Air’s Electrified Goal
Contending for the honor with Harbour Air in Canada, Quantum Air strives to become the world’s first all-electric airline, “disrupting the regional air travel sector with an environmentally friendly and lucrative alternative for travelers.”
Their web site suggests they will offer intra-city, inter-city and even sub-orbital options to their clients. They are positioning themselves to be environmentally friendly in all realms, with craft such as the Surefly (below) and the Bye range of two- and four-seat eFlyers.
Bye Aerospace’s Success So Far
George Bye has positioned his company to be a leader in training and cross-country electric aircraft. If his partnership with OXIS can bring about the 2X batteries and greater safety promised by its design, electric trainers and passenger-carrying light aircraft could be competitive with their fossil-fueled cousins. With the training and operational partners now formulating their plans, we look forward to their making aviation more sustainable, affordable, and accessible.
Thank you’s to Diane Simard, VP of Bye Aerospace and Beth Stanton of the EAA for calling these developments to your editor’s attention.
In a highly unusual approach, two NASA researchers have combined a flow battery system with a rim-driven propeller drive system. Presenting at the Sustainable Aviation Symposium 2019 at UC Berkeley,Robert McSwain and Jason Lechniak detailed their AQUIFER Project, currently underway in the NASA Armstrong Flight Research Center at Edwards Air Force Base.
On Day Two of the Symposium, Jason headed the presentation with a discussion of the implications of this and McSwain’s work on overall energy economy and NASA eVTOL discoveries. Robert followed with a technical description of the Nano Electrofuel (NEF) Aqueous Flow Battery and Rim-driven Motor (RDM).
“AQUIFER establishes technical feasibility of an early-stage technology, a high-energy density, aqueous-based, flow battery, resulting in a near-term increase of 1.7 times range over an all-electric battery, while retiring fire and explosion hazards associated with lithium-based chemistries. The… flow battery will be integrated with a rim-driven motor (RDM) as a multi-functional design to eliminate conductive EMI and weight from long cable runs, and provide liquid cooling from the aqueous fuel. When successful, the technology provides an improved safety energy storage solution for emission-free electric propulsion in commercial aviation.”
A paper on the project informs, “The Energy Economy of the project concept is presented as a potential renewable or green energy [sustainability] for utilizing in-place infrastructure. The nano-electric fluid energy charge-use-recharge cycle is presented using renewable energy input from solar, wind, and hydroelectricity.”
NASA has worked with Influit Energy on the creation of nano flow-cell batteries
NASA explains the hopes for the combined systems as providing safe, non-flammable power that reduces system losses, eliminates emissions and arcing, and reduces cooling and cabling requirements.
Nano Electrofuel (NEF) Aqueous Flow Battery
One benefit of NEF is the ability to simultaneously achieve high energy density and high power density based on the solubility limits of the redox (reduction-oxidation) compounds used.
NASA will develop the NEF battery chemistry in two steps. Gen 1 chemistry is slated to enable 100 milli-Amps per square centimeter with a pack-level specific energy of 125 Watt-hours per kilogram and 350 Watt-hours per liter. This would be for a four-passenger aircraft in the X-57 Maxwell size and weight range.
Gen 2 will rise to 200mA/cm2 with a pack-level specific energy of 530 Wh/kg (for an X-57 reference craft).
NASA is striving to achieve a specific energy density of 600 Watt-hours per kilogram at the system level. For comparison, George Bye of Bye Aerospace reports that lithium-ion packs in his eFlyer 2 are now at 260 Wh/kg.
Rim-Driven Propeller (RDM)
A Rim-drive propeller reverses the normal geometry of a hub-driven prop. Instead of being driven from the centrally-located hub, the propeller is pushed by a drive around its rim. Boats use rim-drive thrusters to help with docking and other close-in maneuvers, and reported in this blog last year. Similarly, Franco Sbarro designed a hubless wheel for motorcycles and automobiles in 1989.
Franco Sbarro’s 1989 hubless wheels on a futuristic motorcycle
One thing piqued your editor’s interest about the RDM, though. NASA’s illustrations show a very thin chord (disappearing to a point) at the center of the propeller and a wide chord at the outer limit, or rim. People like Jack Norris and Paul Lipps taper their propellers to the narrowest chord at the outer portion, partly to maintain fairly constant Reynolds numbers along the propeller length.
Paul Lipps took Jack Norris’ advice and designed props with highly tapered blades to maintain reasonably constant Rn. They were highly efficient.
Your editor asked Robert McSwain about the reversed (or inversed) Reynold numbers that would come with the wider part of the propeller blades being in the fastest part of the airstream. He responded, “…This was one of the design challenges in the Rim Driven Fan. We considered this a design trade for our team between aerodynamic efficiency and structures. If we maintained Reynolds by decreasing chord as airspeed increased the structural requirements for the materials became an issue. Another interesting feature for the RDF includes the root being on the rim, the root now has to deal with compression instead of tension. This point you reference was an example of the very unique and interesting design challenges associated with the RDF. The “optimal” RDF design for our thrust and airspeed design conditions is still not known, but we have tried to use this first design iteration to support our prediction/design tools. I hope with future work we can determine an “optimal” design vetted with proven design/prediction tools.”
One possible benefit of this type of design is that tip losses would be reduced or eliminated, the tip being “capped” by the rim and surrounding structure. We will have to see how actual tests either verify the original calculations or lead to changes in the design.
Both Robert and Jason currently work on the X-57 project, but each has a range of experiences that have led to their current assignments.
Robert has over five years with NASA and is now a co-principal researcher on the AQUIFER project. One item of connected interest was his work on the GL-10 Greased Lightning project.
NASA’s GL-10 Greased Lightning at Langley Research Center (LaRC)
Jason has performed a varied set of investigations for NASA, outlined in his background for SAS 2019. Your editor found 2017 NASA award interesting, for the “Smartest Failure” (along with others) on the X-56 project. That involved a highly flexible airframe used to test the limits of aeroelasticity on high-aspect ratio wings. Later research led to an improved airframe which overcame the problems and exceeded those limits. His PowerPoint presentation on comparisons between “Manned Versus Unmanned Risk and Complexity Considerations for Future Midsized X-planes” is worth a look.
The X-56A “MUTT” (Multi-Utility Technology Testbed) flies a research flight in the skies above Edwards Air Force Base.
With flight tests set for the next year, we look forward to their ongoing work with AQUIFER and the X-57 Maxwell.
With 2020 lurching into life in some turbulence, HopFlyt promises a smooth, above-the-fray experience. A look back at an innovative aircraft designer, the new variant applies electric power and new structural techniques unknown when Willard Custer had his inspiration. HopFlyt is a modern interpretation of that vision, with distributed electric propulsion, 3D-printed components, and simplified control systems.
Willard was a far-sighted soul in the 1940’s, when aircraft were either all wood, all sheet metal, or mixed structures of wood, chromoly tubing and fabric. The composites that freed designers for swoopier things were a few decades away.
Willard Custer’s Big Idea
Reputedly a descendant of George Armstrong Custer, Willard Custer envisioned a propeller in a semi-circular channel that might produce lift as well as thrust. This blog channeled that history in an earlier article on HopFlyt in 2017.
While you can see real-life footage of the original channel wing concept in that entry, we turn to Tom Stanton, who built a small-scale version of the idea and collected data from a fairly-sophisticated test rig, load cells and all.
Today’s Channel Wing Champions
HopFlyt’s founders and executives are residents of Baltimore, Maryland, as was Willard Custer. The three leaders have extensive aeronautical experience, and two were highly-experienced Marine pilots.
Rob Winston, founder and President, “Has been a pilot for over 35 years, 22 of which were spent flying high-performance military aircraft. His job experiences include former NASA Test Engineer; Operational Test Director and Operation Test Pilot for the United States Marine Corps; and Presidential Nuclear Strike Advisor.” His awards include the National Defense Industrial Association, Marine Corps Test Pilot of the Year for 2004.
HopFlyt’s structure supports a complex wing configuration that distributes thrust through two channels on each wing
His wife, co-founder and Vice President at HopFlyt, Lucille Winston, “Is a former NASA Test Engineer with experience developing environment-ready hardware for satellites, the space station and the space shuttle.”
At HopFlyt, Lucille is leading the effort to integrate multiple electric motors, control, navigation and communications systems, while supervising the building, manufacturing and testing of the HopFlyt aircraft composite wings and propellers. She has also helped create aviation combat survivability systems for many service branches.
Full-size channel for one pair of counter-rotating propellers
Co-founder, Chief Financial Officer and Chief Test Pilot at HopFlyt, “Rory [Feely] is a military Experimental Test Pilot and Marine Corps aviator that has been flying high-performance aircraft for over 20 years.” In four deployments, he flew over 300 hours in combat. He has deployed four times and flown over 300 hours in combat. He has a BSc. in Physics (Honors), an MS in Aerospace Engineering and an MS in Technical Program Management. Rory and the HopFlyt team want to save the world from traffic jams and exhaust pollution.
HopFlyt executives and build team show off full-size fuselage
Here we see him promoting that vision in a 2019 TED Talk. His “pitch” emphasizes the economic and environmental costs of continuing in the vicious cycle of gridlock and fossil fuel consumption. His answer would save money, the natural world, and best of all, the time we now waste sitting in a single-occupant, idling machine being bored and frustrated.
Making It Real
HopFlyt is working to realize its design goals for its Venturi electric Vertical Take Off and Landing (eVTOL) vehicle. Extremely different from Uber concepts and similar craft, Venturi will rely on the added lift of the channel wing to gain a potential advantage. Its variable-incidence wings will allow the simplification of control, with no need for conventional ailerons, flaps, rudder or elevator.
The team is 3D printing full-scale parts and performing flight tests on models, again gaining valuable data that backs up what Tom Stanton demonstrated with his models. As their work progresses, we can count on hearing more from Baltimore.
We’re not there yet, in the land of flying cars and even motorcycles. But we do have some pretty good images of where we are and where we might be headed. CNBC produced some pretty thoughtful and well-researched pieces on a major problem plaguing all of us who live within bumper distance of one another – and some plausible solutions. Both videos touch on urban air mobility.
How Much Do Traffic Jams Cost the U. S. Economy?
Gridlock, traffic jams and delay – they all frustrate us daily if we live in a big city. They take away from family time, pollute the air, and drive us to distraction. This video ends with an optimistic take on the benefits sky taxis might bring to groundlings everywhere. We could use cleaner skies, more time at home, and more Zen-like minds. You might learn how to handle the challenges of heavy traffic, too.
Why Don’t We Have Electric Airplanes Yet?
Since Hanna and Barbera showed a modern family flitting about in a flying car, and James Bond went bounding about with a jet pack five decades ago, we may well wonder why real life hasn’t been able to emulate the fantasies of our youth. This video gives a few insights into that question and shares some optimistic possibilities for the future.
What to Do? The NASA ARMD* Urban Air Mobility Grand Challenge
The Challenge, taking several years starting in 2020, will involve testing different approaches to producing a realistic, reliable, functional set of advanced urban air mobility systems. This will require individual and collaborative efforts leading to the Grand Challenge, “a full field demonstration in an urban environment that tests the readiness of companies’ vehicles and airspace operators’ systems to operate during a full range of passenger transport and cargo delivery scenarios under a variety of weather and traffic conditions.”
Atlanta, Georgia in an urban air mobility future
According to NASA, “Its objectives are to:
• Accelerate technology certification and approval.
• Develop flight procedure guidelines.
• Evaluate communication, navigation and surveillance options.
• Demonstrate an airspace system architecture based on NASA’s Unmanned aircraft systems Traffic Management (UTM) construct.
• Collect initial assessments of passenger and community perspectives on vehicle ground noise, cabin noise and on-board ride quality.
We can start 2020 with an optimistic view that progress in electric flight may very well accelerate to new levels in the new year.
In a new partnership agreement, Uber Elevate recently added Joby Aviation to its stable of aircraft companies which are to supply craft for its Urban Air Mobility program. Joby builds electric motors, 12 of which line the wing of NASA’s X-57 Maxwell, with two larger motors for forward thrust when the small units are shut down.
This inventory of electric motors on the NASA project gives Joby a certain entrée to interest from the Urban Air Mobility movement, and it’s received that interest from Uber. Well financed in its own right, Joby has committed to meeting Uber’s desire to have operating sky taxis in the air by 2023, as reported by Andrew J. Hawkins in The Verge.
We have written about Joby several times in the past, including this 2014 report that includes an early rendition of the Maxwell project.
Joby S4 computational fluid dynamic rendering of complex air flow around rotors
Much has happened for Joby since then. Hawkins picked up the story in 2018. “Joby is the brainchild of inventor JoeBen Bevirt, who started the company in 2009. The company operated in relative obscurity until 2018, when Joby announced it had raised a surprising $100 million from a variety of investors, including the venture capital arms of Intel, Toyota, and JetBlue. The money helped finance development of the company’s air taxi prototype, which has been conducting test flights at Joby’s private airfield in Northern California.”
Hawkins quoted from a Bloomberg report about two reporters allowed to see an otherwise secret test flight on Woodpecker Ridge, high above nearby Santa Cruz.
“The pilot managed a vertical takeoff, 15 minutes of flight in a 15-mile loop, and a safe landing. Powered by electric motors and sophisticated control software, the taxi performs like a cross between a drone and a small plane, able to zip straight up on takeoff and then fly at twice the speed of a helicopter while making about as much noise as a swarm of superbees. Bevirt says thousands of these sky cabs will one day shuttle people around cities, soaring above the conventional traffic below.” This surprising report didn’t seem to elicit a great deal of curiosity from the press, but recent news suggests it enticed other investors into looking more closely. A video at that time suggested what a two-seat, Joby sky taxi might enable.
Joby has since become the seventh partner of Uber for their Elevate program. Hawkins, in a December article, explained, “Unlike the dozens of other companies that are currently building electric vertical take-off and landing (eVTOL) aircraft, Joby has kept much of its project under wraps. The few renderings that are out there show a plane-drone hybrid with 12 rotors and room in the cabin for four passengers, though a spokesperson previously cautioned that what Joby is working on now is ‘entirely new.’”
A multi-year contract between Uber and Joby promises “urban air taxi service in select markets.” Joby will supply and operate its craft, and “Uber will provide air traffic control help, landing pad construction, connections to ground transportation, and, of course, its ride-share network reconfigured to allow customers to hail flying cars rather than regular, terrestrial ones.”
One wonders how Uber’s air traffic control help will interface with plans from NASA and the FAA. And other sky taxi firms, for that matter. Joby will join Uber’s other partners in providing aircraft for the project – all with significantly different configurations. The others include Jaunt, Embraer, Pipistrel, Karem Aircraft, Aurora Flight Sciences, and Bell.
Hawkins reports, “Bevirt, Joby Aviation’s CEO, said he believes air taxis will enable people to get to their destinations ‘five-times faster than driving, reduce urban congestion and accelerate the shift to sustainable modes of transit.’ In a statement, he said he was excited to join forces with Uber. Eric Allison, head of Elevate, praised Joby as ‘a real technology leader whose vehicles aim to be designed to enable a safe, quiet, and affordable service for Uber Air riders.’”
The image below shows Joby’s work force today. Six years ago, when your editor was privileged to visit the Joby site, there were about a dozen engineers working on the then current project.
Today’s work force at Joby, much larger than the dozen engineers six years ago – with more to come
The larger group today will grow, with Joby offering 142 openings in a wide range of engineering and technical area. Uber Elevate has 12 openings, mostly in the bay area, but with one lucky research scientist in machine learning getting a spot in Paris. Analysts have said the Sky Taxi business could lead to a $318 billion enterprise from 2020 t0 2040. Joby and Uber alone could account for a big part of that bright future.