Aquifer: Flow Batteries and Rim-driven Motors

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.

Interesting Backgrounds

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.


HopFlyt Hops into the Next Decade

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.


Greeting the New Year with Hope

Two Videos to Ponder

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.

*Aeronautics Research Mission Directorate


Joby and Uber Elevate Form Partnership

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.’”

Joby’s Growth

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.


Dr. Jangwoo Kim has a resume’ that puts a great many qualifications together that spell “battery designer.”  He has a B.S. degree in chemical engineering from Yonsei University, one of three “Sky Universities” regarded as South Korea’s most prestigious.  At Cornell University, he received M. S. and Ph.D degrees in chemical engineering, and then worked for LG Chem on lithium-ion battery pack design.  After that, he returned to Cornell to work on his Ph.D, investigating “next-generation rechargeable battery technology, including Li-Air and Li-Sulfur, specialized in inorganic nanomaterial synthesis and polymer processing via an electrospraying method.”  He joined IBM Research, Almaden Research Center in 2016 and participated in the Battery 500 project, aiming to build a battery pack with a specific energy of 500 watt-hours per kilogram.   We see the project leader, Dr. Winfred Wilcke, in a short video about that project.

Battery 500 intended to reduce or eliminate heavy metals such as cobalt from the cells.  Cobalt is not rare, but it is expensive, priced at $33,000 per metric ton (compare to aluminum at $1,725 per metric ton) and found in areas where conflict and exploitation prevail.  Incidentally, cobalt-related illnesses are found in its incorporation in alloys used in hip-replacement prostheses and even through excess beer consumption (cobalt being used to reduce foam).

Adding to IBM’s research, as noted in his SAS 2019 introduction, new battery technology Jangwoo has helped invent “can potentially be a breakthrough for electric aircraft or other high power applications.”

IBM Almaden Battery Lab – Battery tester and cycler.   The battery uses three new, proprietary materials, including a cobalt- and nickel-free cathode material and a liquid electrolyte. The unique combination is able to suppress lithium metal dendrites during charging, which lowers the chances that the battery will catch fire

As a Research Staff Member / Principal Investigator, Dr. Kim is leading a team to accelerate the commercialization of the technology in collaboration with external and global partners. His research activities are currently focused in electrochemistry and advanced materials for energy storage and AI hardware devices.

In a press release written by Young-hye Na, Manager for Materials Innovations for Next-Gen Batteries, IBM Research, IBM announced the results of the matters Jangwoo spoke of at SAS 2019.  The new batteries are reputed to outperform existing lithium-ion batteries “in multiple measures.  Depending on the application, this family of batteries can be modified to deliver on critical performance factors.”

Batteries From Seawater

The main task seems to be to remove cobalt and other heavy metals because of adverse effects on human health and the environment in general.  In response, IBM says, “Using three new and different proprietary materials, which have never before been recorded as being combined in a battery, our team at IBM Research has discovered a chemistry for a new battery which does not use heavy metals or other substances with sourcing concerns.”

IBM adds, “The materials for this battery are able to be extracted from seawater, laying the groundwork for less invasive sourcing techniques than current material mining methods.”  Potentially less energy intense, too, not requiring the large machines necessary in heavy-duty mining and possibly less energy intense in extracting the needed materials from ores and other mineral components.

Starting at 1:30 in this video, the dangers of cobalt and IBM’s response to these are combined.  Watch the rest of the video for EV-related items.


IBM promotes the battery in costing less, charging faster, and having higher power and energy densities.  They claim greater “greater energy efficiency” and “low flammability.  Without divulging much about the “new and different proprietary materials” involved.  IBM does disclose a cobalt and nickel-free cathode material and a “safe liquid electrolyte with a high flash point, probably preventing negative results from overheating.  The electrolyte also prevents dendrite growth, a cause for rapid battery depletion and even short-circuiting.

With safety well established, how does the new battery perform?

Because of the elimination of heavy metals, the battery is lower cost than equivalent Li-ion cells.

It charges faster, with, “Less than five minutes required to reach an 80 percent state of charge (SOC), without compromising specific discharge capacity.”

It has a power density of more than 10,000 Watts per liter, containing high power in a small area – great for aircraft.

Just as important, its high energy density, 800 Watt-hours per liter, is comparable to state-of-the-art Li-ion batteries.

It has excellent energy efficiency (sometimes referred to as Coulombic efficiency) returning 90 percent of the energy used to charge the battery.

Dr. Kim’s work involves moving the laboratory-level cells into larger commercial, scalable production.  IBM has partnered with Mercedes-Benz Research and Development North America, Central Glass, one of the top battery electrolyte suppliers in the world, and Sidus, a battery manufacturer, to create a new next-generation battery development ecosystem.

Working at Almaden may enhance this effort, the site a major Artificial Intelligence (AI) research center.  Researchers use a “technique called semantic enrichment to further improve battery performance by identifying safer and higher performance materials. Using machine learning techniques to give human researchers access to insights from millions of data points to inform their hypothesis and next steps, researchers can speed up the pace of innovation in this important field of study,” according to the press release.

Comparison with Tesla Batteries

Tesla’s recent 21270 (21 mm diameter x 70 mm length) cells have the following specifications.  Without knowing the IBM’s battery weight per liter, true comparisons will be difficult.  Other factors will affect the total weight of the battery pack.  Since the IBM battery is reputedly less likely to ignite, it might need less weighty enclosures, for instance. Additionally, Tesla has made a point of removing cobalt from its batteries.

Property Value Unit S
Length 70 mm k
Diameter 21 mm k
Volume 24.250 mm3 c
Weight 66 gram e
Voltage 3,7 V e
Charge 5.750 mAh k
Capacity 21,275 Wh c
Energy density 877,5 Wh/L c
Specific energy 322,3 Wh/kg c
Density 2,72 kg/L

The Tesla batteries have an edge in power density (Power density = power/volume = W/liter), but other factors such as being heavy-metal free and flame resistant may be of over-riding concern for designers.  Besides, this is the first round for IBM’s cells, and further development may help IBM reach higher numbers.  As it is, IBM’s new batteries are significant improvements over existing lithium batteries.


A Joyous Boxing Day Electrified

Boxing Day is a holiday unique to the British Empire, a day-after Christmas gift-giving celebration in which the well-off gave gifts to their servants.

Yahoo Entertainment explains, “While there is some dispute over what the name actually means, it’s commonly believed that Boxing Day refers to the habit of aristocratic employees gifting their servants or tradesman on Dec. 26 as a thank you for their work throughout the year. The employers would give them each a box to take home to their family with gifts, bonuses and leftover food.

“Samuel Pepys, a naval administrator and Member of Parliament, is famous for writing in his diary in 1663: ‘Thence by coach to my shoemaker’s and paid all there, and gave something to the boys’ box against Christmas.’”

Certainly some regifting was in action, a chance for the upper class to get rid of fruitcakes sent by maiden aunts, or to reward particularly meritorious servants.

In the spirit of Boxing Day, your editor shares four aeronautical, electrical greetings from particularly meritorious well-wishers, hoping these help overcome the post-yuletide letdown.


Eric and Irena Raymond, both professional photographers and designers of the world’s only solar-powered two-seat tourer. shared this remarkable image.


Photographed with a GoPro MAX and edited with GoPro Fusion, it’s images like this that impelled the camera firm to lead this video and include another shot at the 1:36 mark.  It makes one want to rush out and get a GoPro and a mountain bike or a cheetah.

In a grace note for the season, Eric noted that in the spring, he will start offering rides and flying lessons to visitors to Voghera, Italy.  All you need is a glider license to fly this motorglider.


Taking a lighter note, Kasaero took out Santa with the Eviation Alice, a three-motored craft they helped develop.

Their write-up lets you know that despite their whimsical rendering, they are all business.

Eviation has made it: The design and construction of the innovative new electric aircraft design “Alice” were completed in record time for the Salon Internationale de l’Aéronautique et de l’Espace.

“The dedicated development team of the Composite Cluster Singapore and Kasaero, in cooperation with the Fraunhofer IGCV in Augsburg, structurally dimensioned and designed the high-performance wing of the Alice in just 8 months.”

With type certification of three sailplanes in only four years, Karl Kaeser continues a string of achievements from design work on e-Genius, the Sunseeker Duo, and Ruppert Composite’s Archaeopteryx.

FES/LZ Designs

Luka Žnidaršič and his father are engaged in engineering, product development, and especially in the promotion of their FES (Front Electric Sustainer), a small motor, controller, battery combo that can sustain large sailplanes after launch; or with small craft, even self-launch them.  Their Christmas greeting takes on galactic dimensions.

More terrestrial, this video of their system in action is self-explanatory.

Equator Aircraft


Tomas Brødreskift, CEO of  Equator Aircraft, shares those thoughts with his Facebook friends.  “As 2019 is coming to a close, we wish all our partners, investors, and friends the very best for the holidays and coming new year for you and your families. May all your dreams and ambitions come to fruition.”

The company shares this news, too.  “Norwegian Equator Aircraft has entered into a collaboration with Danish Nordic Seaplanes to develop the next generation seaplane.

“Danish  Nordic Seaplanes operates commercial seaplane routes between Copenhagen and Aarhus. Together with Equator Aircraft, they will further develop today’s two-seater prototype into a four-seater version, for commercial missions.

“Electrification of aviation is soon a reality. Equator Aircraft is developing the world’s first electric seaplane in the premises at Kjeller Airport near Lillestrøm  .

“The company has this year conducted the first tests of the prototype.”   The first flight out of ground effect took place in April, followed by the water taxi tests below.  Note the reversible propeller, which enables easier maneuvering on water.


With a big event coming at the end of February, 2020, Leap Year will celebrate the leaps designers are taking in making really personal flying devices, with a fly off of machines that have shown promise of meeting the demands of taking off and landing in a small space, being quiet enough not to annoy the neighbors, and transporting the single occupant on a short-range mission.

You could be part of the Leap Day ceremonies, including an airshow and finalists’ competition, to be held at Moffett Federal Airfield at NASA’s Ames Research Center in Mountain View, California.  The event will feature support by Boeing, Google’s Planetary Ventures, and Pratt & Whitney from Thursday, February 27th through Saturday, February 29th, 2020.  Passing on Boeing’s gift to you, register to attend here.

It’s been a great 2019 in electric aviation, with major players entering the arena and funding growing monthly.  Let’s hope 2020 transcends even that.

NOTE: Updated December 27 to make up for sloppy editing that left out Tomas Brødreskift and Equator Aircraft’s greetings and big news.


The CAFE Foundation has announced its partnership with the Vertical Flight Society, formerly the American Helicopter Society (AHS).  VFS is the non-profit technical society for the advancement of vertical flight.

The VFS has 21 different technical committees and two dozen active chapters around the world. There are over 100 Corporate Members and 28 Educational Members.

CAFE worked with the VFS for the Electric Aircraft Symposium at the University of Wisconsin, Oshkosh, during AirVenture 2019.  Now officially combining their efforts, the two organizations are actively planning EAS (Electric Aircraft Symposium) 2020 together.  Additionally, VFS has plenty of other events coming in 2020, probably being energized by the growing interest in Urban Air Mobility and the electric vertical take-off and landing (eVTOL) machines that will make it possible.

Starting early in the New Year, “The Transformative Vertical Flight 2020 meeting will take place Jan. 21-23, 2020 in San Jose, California, with our eVTOL Short Course planned for Monday, Jan. 20 and a tour of NASA Ames on Friday, Jan. 24. A record number of abstracts were submitted for this jam-packed three-day meeting, which includes the following concurrent events:

  • “Aeromechanics for Advanced Vertical Flight Technical Meeting
  • “International Powered Lift Conference (IPLC)
  • “7th Annual Electric VTOL Symposium”

In May, an even larger event will take place.

“The Vertical Flight Society’s 76th Annual Forum & Technology Display is the world’s leading international technical event on vertical flight technology. The conference, which will beheld at the Palais des congres de Montreal, will span 3 days and include over 250 technical papers on every discipline from Acoustics to Unmanned Systems, as well as dozens of invited presentations and discussions by leaders in the military, government agencies and industry.”

Participants for all the above events and others sponsored by the organization must be members of the Vertical Flight Society.

CAFE and the VFS will enjoy the benefits of displaying together at Oshkosh and supporting one another at myriad events throughout the year.


Rolls-Royce is perhaps the epitome of Britishness, going back to 1904, when Henry Royce, founder of a successful mechanical/electrical business, met Charles Rolls, a successful car dealer in London.  Together, the founded the company which came to be known as Rolls-Royce.  By 1906, their Silver Ghost was known as “the best car in the world.”  That quality was inherent in their first aircraft engine, the Eagle, “providing some half of the total horsepower used in the air war by the allies.”  It provided the power in 1919 for the first direct flight across the Atlantic and the first flight from England to Australia – both in Vickers Vimy aircraft.  This led to racing success, with early V-12 engines by R-R powering Schneider Cup racers in the 1930’s, leading to the Merlin, which powered Hawker Hurricanes, Vickers Spitfires, and P-51 Mustangs.  Their current ACCELL project hopes to continue that tradition.

WWI Eagle aircraft engine production line. R-R Eagles would power over 50 percent of allied craft in the Great War

Rolls-Royce would love to have another round of victories to continue their successes, and now are unveiling something that has been seen mostly in computer renderings for the last several years.  Others, including YASA (Yokeless and Segmented Armature) axial flux motors, “Are smaller and lighter than any other motors in their class due to our more efficient use of key magnetic and structural materials. The YASA (Yokeless and Segmented Armature) motor topology also significantly reduces manufacturing complexity, making the motors ideally suited to automated volume production,” according to the company.  Nothing could be more British than the motor’s Oxford pedigree, a product of research that company founder and Chief Technology Officer Tim Woolmer performed at the University.

The P1E

Below, we see the result of work by Electroflight.  They created the P1E, a special race plane with two YASA motors swinging counter-rotating propellers.

Electroflight P1E with English Electric Lightning fighter – both have two power units

Electroflight recently partnered with Ansys, an American software firm (with nine offices in Great Britain) contributing high-level visualization to the design process.

“We will be using ANSYS Fluent as we continue work on Rolls-Royce’s ACCEL Electrical Project, as we help produce the world’s fastest all-electric airplane.”



Going beyond the P1E, ACCELL (Accelerating the Electrification of Flight – a messy acronym) will be airborne in spring 2020, according to Aviation Week.  Here are the project goals, with appropriately heroic music.

Electroflight defines themselves as, “The leading supplier of world-class Energy Storage Systems in aviation and other related technologies.”  Working on a high-density energy package that puts three YASA motors in tandem to produce 500 horsepower.  YASA explains that, “Even during the record run the all-electric powertrain delivers power with 90% energy efficiency and of course zero emissions. (In comparison, a Formula 1 race car tops out at close to 50% energy efficiency).”  Because of the enormous torque involved, 400 Newton meters continuous per motor (297 foot-pounds), the motors can pull ACCELL along effortlessly, with a much lower noise level than petrol-fueled machines.

According to Aviation Week, “The tail-sitter aircraft, which is based on a heavily modified version of the diesel-powered Nemesis NXT Big Frog sport racing aircraft, currently is being fitted with the [electric] propulsion system.  Imagine it with half the noise.

Ground tests of the integrated aircraft and propulsion system already are underway using a test airframe dubbed the ‘ion bird.’ Rolls says ‘planned tests over the next couple of months include running the propulsion system up to full power as well as key airworthiness checks.’”

With three of these powerful, torque-plenty motors powering one propeller, the craft will be wafted along like a World War Two fighter, a fitting reminder of Rolls-Royce’s significant part in world history.  We can hardly wait to report on the planned record run.


Help Promote Electric Aviation

Beth Stanton, an aerobatic pilot and superb writer (you can read her articles in Sport Aviation), shares the following action item.  Readers are invited to comment to the FAA by December 31.  Your comments could have a big effect promoting electric flight, especially in flight training.

Beth Stanton enjoying her favorite type of flying


“Progress on affordable electric training is happening!

 “Joseph Oldham, director of the Sustainable Aviation Project (SAP) asked me to pass this information along –

“The SAP petition to the FAA for exemption to operate 4 Pipistrel Alpha Electro Aircraft with the issuance of a Special Light Sport Aircraft airworthiness certificate to conduct flight training is now posted for public comment:

“Comments must be received by 12/30/19.

Locations for Sustainable Aviation Project airports enable cross-country flights between participating sites

“The progress of the Sustainable Aviation Project has been featured in the past few  years in two innovation features in EAA Sport Aviation magazine. An article with the latest updates is slated for the May 2020 issue of EAA Experimenter magazine.

 “Details about the mission of the Sustainable Aviation Project may be found here.
“Please feel free to pass the petition along to your associates. Let’s help get the word out!
We’ve promoted the Project in this blog extensively, since it’s a first attempt to provide certified flight training for electric aircraft:

Why This is Important

Read up on the Project and help show the FAA that electric flight training is worthy of their support.
As explained by Clean Technica recently, “Nonetheless, at stake for Pipistrel is the Special Category Light-Sport Aircraft (SLSA) designation, a highly sought-after airworthiness certificate for light-sport aircraft. It is issued to those that meet the definition of light-sport aircraft (LSA). So far, the Pipistrel Alpha Electros only have the restrictive Experimental status. They can’t be used for training in the US, which is what they were designed for. These 4 US Pipistrel Alpha Electros can only be flown privately, not for commercial purposes.”

A pair of the four Pipistrel Alpha Electros awaiting SLSA certification

Nicholas Zart concludes, “An easier path to SLSA status would open the doors to flying electric airplanes and training planes. A new generation of pilots would have an easier and more affordable way to get into the aviation industry. Considering that the aviation industry is finding it more difficult to find pilots, this makes perfect sense in an otherwise less than perfect scenario. On a personal note, I could visit family, friends, and fly into airports to cover UAM news. The more I think about it, the more pressing the idea is becoming.”

Showing why speed is of the essence, other than the December 30 deadline for comments: “The other hidden problem is that electrifying aviation and going through the many years required for certification means that the technology certified will be obsolete by the time it is approved. Electric aviation is like what desktop computers were a few decades ago, upgradeable if it is to be financially worthwhile.”

Those wanting to advance clean aviation have a golden opportunity to make their voices heard, and good reason to raise them.


Amprius, Airbus, Silicon and Batteries

Batteries are a tough study.  We see many different roads being traveled in attempts to reach the Nirvana of the lightest, most powerful energy storage cell ever.  We see continuing shortfalls because of the much chemistries that seem never to work out as hoped.  Several recent articles, though, showed links that forced your editor into a deep study of battery developments first heard about a decade ago.  These involved Yi Cui, Stanford professor and battery guru, silicon electrodes, and a new electrolyte that holds thing together.    Presaging recent developments, your editor first heard Yi Cui present at the 2009 CAFE Foundation Electric Aircraft Symposium.  Then, he predicted, based on the theoretical limits for silicon-based electrodes in batteries, that we would see 10X (greater energy density than then available) batteries in the not-too-distant future.  A decade later, his company Amprius may be edging toward that goal with new funding from Airbus.

Since then, Cui, his students and associates have helped boost the energy density of today’s batteries to about the two-or-three-X level from that of the decade ago.  A significant improvement, it’s still disappointing knowing what the possible gains might be.

Cui and others are doing even more to remedy the seeming lack of progress.


Yi Cui organized a company to make commercial inroads into the battery market, for instance.  Up to now, Amprius has been somewhat quiescent, advertising only for new and essential researchers on its web site.  Now, since a partnership with Airbus and cooperative development o the Airbus Zephyr project, the website pops with images, charts and the answer to the question, “Why Is Battery Technology Evolving So Slowly?”  The answer seems to be “Chemistry.”  While electronics evolve rapidly, “Batteries improve by making advances in chemistry and materials science.”  A somber last sentence explains, “Many of the chemical processes used in modern batteries have reached their limit.”

Amprius compares rapid development and improvement of electronic and mechanical devices with the relatively slow growth in energy storage.

Airbus has selected Amprius Inc. of Fremont, CA to power its Zephyr project. Zephyr is a light, unmanned platform which made its first flight in 2014 and operates at stratospheric altitudes and low speeds for several weeks at a time.  This HALE (High Altitude Long Endurance) machine can provide large area surveillance for weather forecasting, fire oversight, and military logistics.

Until two years ago, Sion Power in Utah provided its Licerion lithium-sulfur cells to power Zephyr.  Airbus seems to have switched partners and Sion Power has switched battery composition, now relying on lithium metal for its energy storage.  According to Sion, its cells are no longer flying on Airbus Zephyrs.

Silicon Nanowires

Amprius is not yet at the its decade-old goal, but seems to be making progress, noting energy density levels apporoaching 500 Watt-hours per kilogram – more than double most available lithium batteries.  With silicon nanowires at their electrode core, the silicon attempts to swell under charge/discharge cycles, but is constrained by the construction of the wires. This was a problem that kept earlier attempts at silicon batteries from success.

Amprius silicon nanowire seen through scanning electron microscope

Amprius explains four major factors in the nanowires:

  • Nanowires tolerate volume expansion and are rooted to the substrate.
  • Nanowires have micro and macro porosity that accommodate swell.
  • Nanowires improve Solid-Electrolyte-Interphase and cycle life.
  • Anode thickness is reduced to half of a graphite electrode thickness.

The cells are already being used in High Altitude Pseudo Satellites (HAPS), Conformal-Wearable Battery Packs, Quadcopters and Electric Vertical Take Off and Landing (e-VTOL) Vehicles, giving lots of opportunity for further development and testing.

Airbus and the Zephyr

In a joint press release Airbus and Amprius announced a new partnership between the battery maker and Airbus Defense and Space, with promises of financing from Airbus.  The funds will help “drive the development of higher volume production capacity along with higher energy density cells for Airbus Defense and Space aerospace programs, including the Zephyr High Altitude Pseudo Satellite and Urban Air Mobility innovation initiatives.”

Jana Rosenmann, Head of Airbus Unmanned Aerial Systems, explained the benefits to both partners. “This partnership reinforces the link between two market leaders, the newest generation batteries of the market matched with the most advanced HAPS program. Zephyr is currently the only one operating in the stratosphere at an average altitude of 70,000 and running exclusively on solar power, providing persistent local satellite-like services and supporting a wide range of applications and tasks.”

Jon Bornstein, COO of Amprius added, “We are extremely pleased to be working with Airbus and supplying batteries for the Zephyr program.  The incorporation of Amprius’ 100% silicon nanowire anode-based lithium ion batteries into the Zephyr platform represents an important validation of this technology. Likewise, our development of high energy power cells for Urban Air Mobility will enable exciting opportunities in new aviation markets.”