A battery with 560 Watt-hours per kilogram, a stable long life, and no fires.  What’s not to like?  Researchers at Helmholtz Institute Ulm (HIU), founded by the Karlsruhe Institute of Technology (KIT) in cooperation with the University of Ulm, have come up with a dual anion, nickel-rich cathode, lithium-metal battery that, although in early stages of development, may point a way forward.

Academic journal Joule reports, “High-energy batteries, in particular lithium batteries, are the key to achieve carbon-neutral mobility…. However, it is foreseen that a fully electrified mobility and transportation can only be achieved by the development of batteries employing lithium metal as the negative electrode (anode) while still granting long-term cycling performance and safety.”  Safety may be the deciding factor here, especially in electric aircraft.   Coupling the lithium metal anode with a nickel rich cathode seems to pay off for the researchers.  Along with the dual anion liquid electrolytes, they’ve managed to keep things stable and performing well.

Considering the visual impact of recent car fires on the nightly news, and instructions to park your EV outside, buyers might be forgiven for a certain reluctance to embrace an attractive, but iffy, new vehicle.

Helmholz Institute Ulm (HIU) has come up with a battery that can store 560 Watt-hours per kilogram, according to their paper.  It retains 88 percent capacity after 1,000 cycles

(As always, your editor is quick to point out 589 fossil-fuel powered cars per day self-immolated in one recent year.)  CNBC points out, “Vehicle fires are common, generally. According to the National Fire Protection Association, there were 212,500 vehicle fires that caused 560 civilian deaths, 1,500 civilian injuries and $1.9 billion in direct property damage in the U.S. in 2018.”

More Energy, More Risk

Batteries seem to be the never-ending thorn in electric flight’s side.  As batteries gain energy, they seem to become more flammable.  An ongoing recall by GM has virtually pulled all Chevy Bolts off the road, battery manufacturing defects getting the blame.  While the car company is footing the bill (over $1 billion) to replace offending battery packs, battery fire anxiety may replace range anxiety for EV owners.

Stability over its life cycle is a primary feature of HIU’s battery using dual-anion ionic liquid electrolyte (ILE)

Researchers employed a cobalt-poor, nickel rich negative electrode (anode) material along with a dual-anion ionic liquid electrolyte [ILE].  According to the Joule entry, “This electrolyte enables initial specific capacity of 214 mAh g−1 and outstanding capacity retention of 88% over 1,000 cycles with an average Coulombic efficiency of 99.94%. The Li|ILE|NCM88 cells achieve a specific energy above 560 Wh kg−1 based on the combined active material masses.”  Lower cobalt levels are promising because of the controversial conflict and child labor resourcing of that material.

From Academia to Commercial Reality?

The term “active material masses” seems to draw attention, with several comments in GreenCarCongress.com.  “Lab coin cell data is normalized to a real energy density.  This is a bit misleading.”

 

Morphology of HIU battery shows forms of materials under different methods of viewing:                                                                                                                                        (A) Rietveld refinement of the XRD pattern of pristine NCM88 powder.  (Wikipedia explanation: Rietveld refinement is a technique described by Hugo Rietveld for use in the characterization of crystalline materials. The neutron and X-ray diffraction of powder samples results in a pattern characterized by reflections (peaks in intensity) at certain positions.)
(B) Structural model of NCM88. Red, O; light blue, interslab metal; dark blue, intralayer metal.
(C) SEM micrograph of NCM88 and its elemental mapping for oxygen (O), Nickel (Ni), Cobalt (Co), and manganese (Mn).

Another reader commented, “The reference: high energy density of 560 Wh/kg—based on the total weight of the active materials, means that this does not include the inactive and polymeric binder mass. Even if they quoted the Lithium full cell energy density, it is still only a lab specimen. Until a fully developed pouch or cylindrical cell is produced, you can only estimate battery energy density.

“Cuberg does have a product with a 369 Wh/kg energy density (though poor cycle life). Depending on the configuration (pouch, 2170, 4680, etc.) energy density would be in this range. The HIU research extended the cycle life by using a dual-anion ionic liquid electrolyte.”  Combining findings by researchers with commercial developments may be a way forward.  Whether Cuberg (and by acquisition, Northvolt) uses a similar chemistry or a nickel rich cathode is not known.

Swedish Acquisition of Cuberg

Good news comes through in that regard.  Northvolt, a Swedish company, acquired Cuberg, a California-based battery developer.  Cuberg has been working closely with Boeing and other customers, including BETA Technologies, Ampaire, and VoltAero. The company’s investors and financial backers include Boeing HorizonX Ventures, Activate.org, the California Energy Commission, the U.S. Department of Energy, and the TomKat Center at Stanford.

Northvolt has plants in Sweden, Germany, and Poland among other locations, and will, “Establish an advanced technology center in Silicon Valley based on the Cuberg acquisition and is actively hiring top battery industry talent to support these efforts.”  Acting as a bridge between European and North American battery development, the center will, “Bridge ongoing research efforts between Europe and North America. It will also serve as a testbed for methodologies leveraging digitalization, artificial intelligence and machine learning.”

A comparison of cell-stack sizes of conventional lithium-ion batteries and lithium-metal batteries featuring Cuberg’s technology.  Image: Northvolt

Northvolt’s multi-billion dollar backing will help the further commercialization of Cuberg’s efforts.  “’We are very excited to join forces with Northvolt to build the future of clean energy together,’ said Richard Wang, CEO and Co-Founder of Cuberg. ‘Northvolt brings incredible technology and manufacturing capabilities that will accelerate the commercialization and adoption of our lithium metal technology. Their deep engineering experience and bold spirit perfectly complement Cuberg’s own culture of rapid innovation.’”

Close on this announcement, Arizona-based Sion Power is making news at the upcoming Battery Show North America.  We’ll follow up on that in a few days.  Finally, changes and hope are coming to the battery business.

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Pie Aeronefs, a small team of dedicated builders in Switzerland is putting the finishing touches on the UR-1, a V-tailed, battery-winged electric racer expected to fly in next Air Race E series.

“Marc Umbricht’s vision is to create a 4-seater general aviation electric aircraft that shall equal or surpass the performances of standard piston engine aeroplanes. This new generation aircraft will bring a viable and sustainable alternative on the general aviation market.”

To achieve this ultimate goal, the Pie Aeronefs team has a series of iterative designs to explore, starting with a single-seat eRacer.  The small aircraft development firm in La Sarraz, Switzerland is on track to complete the airframe of its UR-1 Air Race E machine soon.

12 Battery Packs

Innovative in the extreme, the small craft will store 12 in-series 10-kilogram (22-pound) battery packs in its wings.  Each 55-Volt pack stores 1.15 kilowatt hours of electricity.

The 13-member team chose lithium-ion polymer cells for their battery packs because they offer, “The best balance between power output and safety, despite the fire risks inherently found in Lithium-ion batteries.”  To protect the batteries and distribute their weight across the wing’s span, the group built a wing “with appropriate rigidity, as a flexible wing may damage the batteries.”  They’ve also designed “an original battery fire protection system in addition to a liquid cooling system.”  Stay tuned for more on this feature.  Part of that may come from the basalt fiber containers in which the batteries are ensconced.

UR-1’s battery packs, six in series in each wing, provide short-duration, high-output burst of power

Heat loss from the electric motor, controller, and other electronics will be dissipated through radiator plates on the inner skin of the fuselage.  This is similar to the radiator tubes that ran down the sides of the Supermarine S5 and S6 Schneider Cup racers in the 1930s.

Supermarine S5 was predecessor of Spitfire, WWII fighter. Tubes running along fuselage cooled engine, much like inner skin on UR-1 cools the motor

One Emrax Motor

All that stored energy will be fed to an Emrax 12-inch diameter motor weighing 40 kilograms (88 pounds), putting out 150 kilowatts (203 horsepower).  That’s projected to be enough to pull the 400 kilogram (880 pounds) maximum weight UR-1 around the pylons at up to 302 knots (560 kilometers per hour or 348 mph).  Racing four laps around the Air Race E course will probably see lower speeds because of the high G-force turns.  The projected 90 kilogram (198 pound) pilot will be subjected to those forces 16 to 20 times during a quick, intense race.

Fixed Gear and V Tail

UR-1 has a fixed landing gear in accordance with the rules, and slotted flaps to slow things down for take-offs and landings.

The V tail is an approach to reducing interference drag, that part of the drag profile that comes from wings butting up against the fuselage, for instance, and tail surfaces interfering with each others’ airflows.  Eliminating one part and making the remaining two perform all functions simplified the airflow, but makes it a little harder to manage the stresses on the tail cone.  That may be why UR-1 has a fairly thick protrusion – looking a bit like what ornithologists call the “Pope’s nose” on a bird.  (Your editor is not making that up.)  Much like the aircraft, the bird may need that for structural reasons, all the tail feathers poking out from the bulbous posterior and needing muscles to move them appropriately.

Certification

On June 18, 2021, the EAS (Experimental Aviation of Switzerland) association approved the UR-1 project. a crucial step to permit the first Swiss all-electric race plane to fly.

In Switzerland, EAS offers support and help to every project in the experimental aviation field. According to Pia Aeronef, “They work with the FOCA (Federal Office of Civil Aviation) and are in charge of the supervision of the construction and the maintenance of self-built planes. The EAS association is actually managing the development of more than 130 aircrafts.”

Future Plans

UR-1 is a simple, straightforward design compared to what Marc Umbricht has envisioned for the future.  Following, if all goes well, could be UR-2, a distributed electric propulsion (DEP) race plane.  That would give way to the UG-3, a certified electric General Aviation craft capable of flying 500 nautical miles at 120 knots indicated air speed.  It could land and take off in 500 meters (1,640 feet).  Finally, Umbricht foresees the UB-4, a long-range short takeoff and landing (STOL) business jet with a 6,000 NM range, cruise of Mach 0.8 (613 mph!), and a 900-meter (2,952-feet) takeoff and landing distance.

It’s nice to see an enthusiastic group keeping a timeline and their ambitions on track.  We wish them well and safe racing.

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Embraer Electrifies Agricultural Aviation

Embraer, a Brazilian aircraft maker with ties to Boeing, has been tilling the clean aviation field for several years.  Their current agricultural craft, the EMB 203, has flown on ethanol for some years – a kind of farm-to-aircraft symbiotic relationship.  Going to the next step toward clean, green aviation, Embraer has since devised an electrical powertrain in cooperation with WEG Equipamentos Elétricos and EDP.

Embraer EMB 203 making low pass along runway at Sao Paolo factory

Embraer is deeply involved in programs headed toward making the skies greener.  This includes everything from their aircraft designs to their “DIPAS PROGRAM – DIPAS (Integrated Development of an Environmentally Sustainable Product).”  This program considers “current and future environmental legislation,” alternative technologies and their life cycles.  The program works toward reducing fuel consumption, CO2 emissions, noise, and maintenance costs, while, “Increasing operational efficiency and comfort for the pilot and passengers.”

Other operations to incorporate electrification of flight include Embraer X’s Eve, the company’s approach to urban aerial mobility, and other efforts to offset or mitigate harmful emissions.  “Embraer says it will develop a range of products, services, and disruptive sustainable technologies, such as electrification, hybrid, sustainable aviation fuel (SAF) and other energy alternatives. The company claims it will also offset any residual emissions that cannot be reduced through efficiency projects, available alternative energy or advancing technology.”

The Plane from Ipanema

Flying since 2004 on ethanol, the predecessor to the current EMB 203 was an early attempt to reduce carbon emissions.  Some find this approach controversial, since ethanol production often entails converting food crops such as corn into aviation fuel.  Electricity can be obtained from more sustainable resources, and thus might be more acceptable to environmentalists and those worried about feeding a hungry world.

The base design has been flying since 1970, and Embraer plans to use it as a testbed for electric power.  Its payload of 950 kilograms (2,094 pounds) is great for spraying large fields, and highly useful for carrying a large battery pack.  EDP-funded batteries combined with the “very light electric motor [from] the large Brazilian electrical company WEG” will allow enhanced endurance.  Technology developed on the Ipanema will be transferred to use on the EVE eVTOL (electric Vertical Take Off and Landing) project and probable future electric projects.

Luis Carlos Affonso, Vice President for Technology and Development at Embraer, explains the importance of the Ipanema.  “The first flight of an aircraft is always an important milestone and the start of our first of… ten emission-free electric aircraft is also an important contribution of our teams and partners on the energy transition in the industry. We strive to find solutions that enable a more sustainable future for aviation, and innovation becomes one along the way Play a key role.”

Embraer’s electric agplane with some of its 1,800 builders, flanked by civilian and military craft produced by Embraer

First flight tests include evaluation of performance, control, heat management, and operational safety.  Embraer hopes to validate computer simulations, laboratory tests and integration of the technology, ongoing since the second half of 2019.

President and CEO Francisco Gomes Neto. “We recognize the urgency of the climate crisis and we are fully committed to a more sustainable future.  We are stepping up our efforts to minimize our carbon footprint by remaining dedicated to innovating solutions that have a broader impact for our customers, our local communities and our aircraft.”

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Three Massachusetts Institute of Technology (MIT) researchers may be on the track of producing hydrogen from a reaction between aluminum (the scrappier the better) and water.  Their “simple way” of generating H2 from aluminum and water can take place anywhere, according to the researchers.

Since groups like ZeroAvia and Pipistrel with the DLR (German Space Agency) and HY4 are working toward at least intermediate-range hydrogen-powered flight, an inexpensive way to produce the gas would be a blessing.  Current methods of producing H2 from fossil-fuel-related materials can be more detrimental to the environment than the promise hydrogen would otherwise bring, however.

Corroding but Not Rusting

Dr. Laureen Meroueh along with Professor Douglas Hart and Professor Thomas Eager at MIT have found a way to react aluminum with water at normal room temperature, leading to the formation of aluminum oxide while releasing hydrogen gas.

Under normal conditions, aluminum exposed to water develops a coating of aluminum oxide.  Stanford researchers in 2000 discovered why this does not become destructive “rust” like that on steel.

Aluminum aircraft don’t corrode because of protective coating. Alclad  Ryan SC-W shines because of labor-intensive polishing

Gordon Brown, Jr., the Dorrell William Kirby Professor of Earth Sciences explains, “Water actually changes the structure of the solid surface.  In the journal I, Brown and others presented the first atomic-level model of what happens when water and aluminum oxide meet. ” As the name would suggest, aluminum oxide is atoms of aluminum and oxygen bonded together.

“But Brown and Trainor discovered that, when water molecules come in contact with aluminum oxide, the aluminum and oxygen atoms on the surface move apart — in some cases separating by more than 50 percent compared to their normal molecular positions.

“As a result, when the outer layer of aluminum oxide gets hydrated or wet, its structure changes just enough to become chemically inert and thus unable to react rapidly with additional water molecules or atmospheric oxygen. This change in molecular structure is why aluminum oxide metal resists corrosion.”  This 20-year-old discovery is key to the MIT researchers’ ability to make H2 from oxidized aluminum.  It takes a little fine tuning, though.

A Little Tuning

The thin oxide layer on the aluminum keeps the aluminum from corroding further, but also prevents it from reacting any further with water.  To counter that, researchers had Novelis, Inc. prepare pure aluminum and special alloy samples with coatings of, “0.6% silicon (by weight), 1.0% magnesium, or both—compositions that are typical of scrap aluminum from a variety of sources.”

The nifty part of this comes from being able to pretreat the aluminum, transport it anywhere, and then generate the hydrogen on site.  More frugally, such pretreatment could take place anywhere with scrap aluminum, an abundant resource near any population center with convenience stores.

At a wildly simplified level, these coatings act as blockers against the creation of further protective oxidation, but allow reactive things to happen – generating hydrogen when the treated aluminum comes in contact with water.

Laureen Meroueh PhD ’20, professors Douglas P. Hart and Thomas W. Eagar used a technique “first introduced by Jonathan Slocum ScD ’18 while he was working in Hart’s research group.”  They pretreated,  “the solid aluminum by painting liquid metals on top and allowing them to permeate through the grain boundaries, as shown in the diagram below.”

Coating aluminum to prevent protective oxidation.  The idea of permeating metal with a liquid may seem counterintuitive, but is necessary to the process

Researchers found the type of coating (a limited sample, admittedly) changes the amount of hydrogen generated and the time over which the reaction takes place.

Aluminum coated with a layer of 0.6-percent (by weight) silicon spikes quickly in forming hydrogen, which a coating of 1.0-percent magnesium enables a high early reaction and a longerl period of production.

Grain size plays a part, smaller grains of aluminum reacting with various coatings to produce higher reaction levels, but varying reaction durations.

Aluminum grain size plays a factor too, enabling permeation by the liquid metal coating

Logistics are important in being able to provide energy in diverse locations.  Recent climate-based traumas (The Texas winter, for instance) show the dangers of having large, highly dispersed needs served by highly localized resources.  Shipping volatile fuels such as oil, gasoline, and liquified natural gas is hazardous, whether by truck, train, or pipeline.  Most of the ingredients for generating hydrogen at its point of use are readily available for most elements of MIT’s approach.

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ZeroAvia Tests 600 kW Motor, Receives Honors

Val Miftakhov, founder and CEO of ZeroAvia, introduces tests of the company’s 600 kilowatt powertrain, mounted high atop their new mobile test bed.  In recent months, the company has achieved some solid recognition.

“In July, 2021, ZeroAvia has successfully tested high-power operation of its flight-intent ZA-600 (600kW) powertrain. The testing has been done on the brand new HyperTruck mobile ground testing platform ZeroAvia has developed based on a heavy-duty M977 HEMTT military truck. The HyperTruck platform is designed to be able to test not only the current 600 kilowatt system for 10-20 seat applications, but also the 2 Megawatt system currently in design phase, targeting 50-80 seat aircraft. The latest series of tests signifies a critical milestone before flight application of these powerplants later this year in the company’s 19-seat test demonstrator.”  Further down the line, plans for a 40-80 seat hydrogen-electric aircraft are in store.

Perhaps the high mounting of the powerplant comes from Head of Drivetrain development, Gabriel DeVault.  His work with NASA’s X-57 Maxwell project involved “flying” a wing and up to 18 motors at over 70 mph on Rogers Dry Lake near NASA’s Armstrong Flight Research Center at Edwards Air Force Base.

The high arrangement would seem to allow operation of the motors and folding propellers out of turbulence that might be induced closer to the ground. That the unit is sized to handle the two-megawatt system under development might require added ground clearance.

ZeroAvia’s HEIST (Hybrid-Electric Integrated Systems Testbed)thundering along on Rogers Dry Lake with the X-57 Maxwell wing high above

Gabe DeVault, the company’s Head of Testing and Applications, has another inducement: Just a reminder that ZeroAvia is hiring like mad! If you want to join us having all the fun here in Hollister, CA USA. Please contact me directly via linked-in. No recruiters please!”

He adds, on the ZeroAvia web site, “The Hollister testing is a significant milestone for our new HyperTruck testbed and ZA-600 that also confirms the operation of our next-generation control system and software. Our US team is excited to support the important work of our colleagues in the UK and ultimately scaling up our proven hydrogen fuel cell integration for larger commercial aircraft engines, which the HyperTruck supports.”

ZeroAvia has procured two Dornier 228 aircraft for next-phase testing. This will kick off further development of the program, which has been recognized by the World Economic Forum as a “Technology Pioneer.”

ZeroAvia has obtained two Dornier 228 commuter craft for testing its new powerplants

Timothy Reuter and David Hyde, writing for the Forum, explain, “…Short-haul flights of less than 600 miles account for more than 17% of total airline emissions that breakthrough technologies such as electric- and hydrogen-powered aircraft can play an important role in addressing – reducing not just C02, but other types of emissions that affect human health and the environment such as NOX and contrails.

“By some estimates, all flights of less than 2,500 miles, representing today more than 50% of CO2 emissions of aviation, could be electrified or powered by hydrogen. And there is no theoretical range limit for aircraft powered with a combination of hybrid electric systems and SAF.”

World Economic Forum prediction on how aviation can achieve a net zero result in emissions by 2050

To top it off, “With their selection as Technology Pioneer, CEO and founder of ZeroAvia, Val Miftakhov will be invited to participate at World Economic Forum activities, events and discussions throughout the year. ZeroAvia will also contribute to Forum initiatives over the next two years, working with global leaders to help address key industry and societal issues.”

“Miftakhov also was recently selected to become a member of the Fuel Cell and Hydrogen Energy Association  (FCHEA) Board of Directors. The organization, “Strives to promote the environmental and economic benefits of fuel cell and hydrogen energy technologies.”

Things seem to be moving rapidly at ZeroAvia, and we can hardly wait to see what comes next in Hollister and the UK.

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A Pulitzer Written in the Sky

Itching to test your electric airplane’s cross-country capabilities?  A new Pulitzer Electric Air Race of over 1,000 nautical miles (1,150.78 statute miles to be exact) between Nebraska and North Carolina will show who has the fastest electric flying machine.

Jim Moore, reporting for the Aircraft Owners and Pilots Association (AOPA), shows the connection between the original Pulitzer Trophy and today’s electric competition.  “Five of the first six pilots to have their names engraved on the Pulitzer Trophy were military airmen clocked around a closed course at speeds starting at 157 mph in 1920, up to a blistering 248 mph by 1925. The trophy was created to inspire innovation, and particularly faster airplanes. That vintage trophy housed at the Smithsonian National Air and Space Museum will be engraved with its first new name in 97 years in 2022, following completion of a 1,000-nautical-mile cross-country race by up to 25 electric aircraft.”

The art deco styling of the Pulitzer Trophy would look good on any aviator’s mantle

Ralph Pulitzer was son of Joseph Pulitzer, whose prizes for literature and the arts are widely recognized.  Ralph created the races to promote speed over closed courses.  Scott Neumann, a retired U. S. Air Force pilot is director of the current competition, which will be run under the auspices of the National Aeronautic Association, the American branch of the Federation Aeronautique Internationale (FAI).

We need to remember that by 1920, aircraft had been evolving for 17 years, with huge technological and government boosts from World War One.  Electric aircraft are starting that evolutionary development once again, and competition will encourage adventurers and scientists alike in promoting that development.

Mitchel Field, New York, 25 November, 1920.  Aptly named Corliss Champion Moseley managed 156.54 mph over a 29-mile triangle course

The planned route for the race runs between Eppley Airfield in Omaha, Nebraska and Dare County Regional Airport in Manteo, North Carolina.  Perhaps more closely tied to aeronautical history, First Flight Airport at Kill Devil Hill, “Has no electric charging infrastructure yet installed, and its amenities are limited to restrooms, a pilot lounge, and Wi-Fi.”

Much as the “record” attempts lately in Europe, Australia, and California, the route will have to accommodate stops for recharging both the airplanes and pilots.  Up to 25 participants will fly heavier-than-air of any type other than drones.  This will be a visual flight rules (VFR) daylight-only trek, and times “between liftoff and landing” will be recorded by “on-board GPS devices provided by [the] NAA (National Aeronautics Association).

Joby’s eVTOL has already proven its ability to fly over 150 miles at speed

The official rules set out the constraints for the race.  “The Pulitzer Electric Aircraft Air Race (“the race”) is a 1000 nm cross-country air race from Omaha, NE to near Kitty Hawk, NC. The race is a multi-day event scheduled for 16 – 19 May 2022. Each contestant must complete the race within a four-day window beginning at the start of civil twilight the morning of 16 May 2022 and ending at the end of civil twilight the evening of 19 May 2022.”

The draft rules can be found here.

Expect a Variety

Beyond that, fixed wing or vertical takeoff and landing craft are on equal terms.  The point is to go from Point A to Point B as expeditiously as possible.  “Electric propulsion is a must, though that electricity can be stored in any combination of batteries and hydrogen fuel cells, optionally augmented by solar panels.”  This seems to enable every type of electric aircraft now flying to participate, and allows the possibility of new, as yet unseen, designs.  The two first place finishers in 2011’s Green Flight Challenge could compete, as well as machines from Pipistel, Bye Aerospace, and any number of home-built craft such as the eSonex or eGull, or even the Sunseeker Duo.

Mark Beierle flying his eGull over his California launch pad

The AOPA reports, “We wanted to design a race that advances electric aviation technology, and promotes public acceptance of electric aviation, by flying real aircraft in real airspace, landing at real airports,” Neumann said. “We have designed the Pulitzer Electric Aircraft Race to provide an open canvas for design innovations, and to be a sort of flying expo for the electric aviation industry.”

The race could use more sponsors to join Signature Flight Support, a network of fixed base operators on airports around the world, and Flight Aware, a flight tracking and data collection service.  The latter service, especially, will allow tracking “the progress of each race aircraft online in real time.”

STEM Programs

Hoping to encourage young peoples’ interest in aeronautics, “The NAA is also partnering with Carrot™, a nationally recognized Science Technology Engineering and Mathematics (STEM) organization, to leverage the Pulitzer Electric Aircraft Race as a STEM educational outreach opportunity.  Fifth and sixth grade school science classes will explore electrical power systems and their application to aeronautical engineering in the semester leading up to the race.  Science classes and clubs entered in the Pulitzer STEM Challenge will apply what they have learned to design their own electric race aircraft.  Students will follow their favorite competitors in real time along with the rest of the world via publicly available internet flight tracking on FlightAware.com and here on the NAA Pulitzer Electric Aircraft Race website.  The class with the best design and presentation will win the Pulitzer STEM Challenge and be invited to Washington, DC for a special VIP guided tour of the National Air and Space Museum and be honored guests at the Pulitzer Trophy presentation event.”  The payoff should be an incentive for science teachers all over America.

Winner of the NASA 2011 Green Flight Challenge, HY4 could challenge the field, already demonstrating 200-mile range and 100 mph speed.  eGenius was a close contender.

Waiting to Hear

The AOPA article ends with a wistful note.  “It was not immediately clear who will be lining up to race from Omaha to (near) Kitty Hawk, with several recharging stops almost certainly required due to physics and current battery capacity. There are more than 300 electric VTOL aircraft currently in development, and a few electric airplanes already in service, with more on the way. Messages sent to about half a dozen industry leaders produced some expressions of curiosity, but no firm commitments.”  Certainly, the Pulitzer Electric Air Race should be a draw, with the public exposure of electric aircraft a grand inducement to participate.

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Skydweller Seeks Ultra-Persistence

Skydweller Aero, an adaptation of Solar Impulse technologies, is working with the U. S. Navy to provide ultra-persistent flight capabilities.  It’s using Solar Impulse Two, for which Skydweller purchased the assets and intellectual property rights.  Being flown in Spain at this time, the aircraft’s 2,900 square feet of solar cells provide two kilowatts of power, and may be augmented by hydrogen fuel cells in future.

In Spain

Skydweller founders John Parkes and Robert Miller have headquarters in Oklahoma City, Oklahoma, but are performing flight tests in Spain, coordinating efforts with the University of Castilla-La Mancha (UCLM).

After successfully completing ground tests that checked the structure and control systems, Skydweller works toward crafting the software that will guide it on unpiloted missions, scheduled to last at least 30 to 60 days.  Such persistence, long sought by the military for ISR (Intelligence, Surveillance and Reconnaissance) missions, is also essential for many future civilian applications.  Co-founder John Parkes explained this to Aviation Today.   “There are certainly differentiated missions that Skydweller can do that no other aircraft can do, but the core of it really is doing things that we do today better, smarter, cheaper, more effectively.  And that is communications — being a node in the sky whether for the military and first responder market or for the telecom world. And for the military specifically, doing intelligence, surveillance and reconnaissance (ISR) missions from an airborne perspective more effectively.”

Certainly recent disasters such as the Bootleg and Dixie fires, which encompass broad areas and last weeks or even months, will require an “eye-in-the-sky” to help everyone from first responders to those performing reclamation efforts.  The idea of being able to observe in many spectrums can help speed search and rescue work, find lost or endangered people, and spot incipient hazards.  The possibilities are endless.

Non-Predatory Behavior

Aviation Today reports, “With 800 lbs of payload capacity, the drone can carry more radar and camera equipment than a MQ-1 Predator, whose primary role is reconnaissance and surveillance, though not as much as an MQ-9 Reaper, which often carries armaments as well.

“The U.S. Air Force recently announced it is looking for a Reaper replacement — called “MQ-X” — to enter service around 2031. Though the Skydweller wouldn’t be able to fulfill all of the capabilities of the Reaper, as it isn’t designed to carry armaments, it could offer greatly reduced complexity and operating costs for ISR missions.”

A Systems Engineering Exercise

Parkes does not expect Federal Aviation Administration (FAA) or European Union Aviation Safety Agency (EASA) approval or certification soon, but does anticipate they will grant waivers for communications applications.  The aircraft is slated to meet FAA Part 23 certification requirements, however.

Integrating “its autonomy systems and ultra-redundant flight control systems…comprise the bulk of the [new] company’s engineering investment.”  Italian aerospace giant Leonardo invested in Skydweller and owns about 17 percent of the firm while controlling one of the seven board seats.  Skydweller raised a total of $32 million in its Series A fundraising, so it would seem well established.

College Links in Castile

A recent meeting between Skydweller and members of the University of Castilla-La Mancha planned, “Future collaborations on innovation, employment and internships for university students.”

Proposed changes for Skydweller

The Government of Castilla-La Mancha has declared the future building of solar drones as a priority.   Their base will be located in the town of Valdepeñas (Ciudad Real), with the intent of “reactivating” economic development in the area.  It’s not stated whether the solar drones will be patterned after Skydweller or will be of different configurations.

Meanwhile, Back in Oklahoma

An electric motor that circumnavigated the globe by air in Solar Impulse 2 will soon have a new permanent home at Oklahoma State University.  Donated by Skydweller, the motor will reside at the school’s Unmanned Systems Research Institute (USRI).

 

Well traveled, one of Solar Impulse 2’s motors will help Oklahoma students gain insight into electric aviation

Dr. Jamey Jacob, OSU professor of aerospace engineering and director of USRI explains, “We are excited to be working with Skydweller Aero on their advanced technology. This is a unique opportunity for OSU students and researchers at USRI to work on cutting edge systems and push the leading edge of aeronautics.  OSU has been working on solar-powered aircraft for over 20 years, but this remains one of the hardest problems in aerospace engineering — to be able to assist in the pinnacle of solar flight is truly exciting.”

The USRI team will test the motor in a propulsion cell in its Excelsior laboratory, gather data, and “determine which projects will yield the most beneficial results.”

Skydweller’s CEO Dr. Robert Miller adds, “University research and development partnerships are one of Skydweller’s top priorities.  We are thrilled to be donating our electric motor to Oklahoma State University’s Unmanned Systems Research Institute and look forward to continued opportunities for collaboration.”

With two universities in Europe and America working to develop expanded capabilities for Skydweller, the future seems to open a wealth of possibilities.  We’re anxious to see what comes next.

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Joby Aero Inc. has displayed its ultra-quiet operation, flown a promised distance and become an investment favorite in the last few months. Now it’s headed to Washington, D. C. to consolidate relations with law- and opinion makers.

Quietude

As a follow-up to its recent demonstration of quietude on Public Broadcasting’s “Great Electric Airplane Race,” Joby staged a head-to-head test of its near silent operation against other aircraft.  Note the perceived noise and the aural signature as each craft passes overhead.

Going the Distance

One thing prominent in Joby’s on-line presence is their promise that their electric air taxi will be able to travel 150 miles on a single charge – including a vertical takeoff and landing.

Flown from the ground by Chief Test Pilot Justin Paines, the machine, “…Took off vertically before transitioning to forward flight and completing 11 laps of a predefined circuit. After more than 1 hour and 17 minutes in the air, the aircraft landed vertically, having covered a total distance of 154.6 statute miles.”

JoeBen Bevirt, founder and CEO of Joby, explained the significance of the speed and distance involved.  “We’ve achieved something that many thought impossible with today’s battery technology.” He added, “By doing so we’ve taken the first step towards making convenient, emissions-free air travel between places like San Francisco and Lake Tahoe, Houston and Austin, or Los Angeles and San Diego an everyday reality.”

Of note, batteries used in the flight were commercially available lithium ion batteries adapted for aerospace use.  With an NMC (nickel manganese cobalt) cathode and a graphite anode, Joby chose these because they allowed VTOL flight and demonstrated cycle life of “more than 10,000 of our expected nominal flight cycles.”  Jon Wagner, Head of Powertrain and Electronics, formerly worked at Tesla, and notes, “We’ve been able to create a remarkably efficient aircraft that can make the most of today’s commercially available batteries.”

Keeping a High Profile

Imagine this short flight demonstration with a longer middle part, the vertical lift and descent being only a small part of the total flight and a 150-mile cross-country excursion inserted in between.  This type of strategy, along with the aerodynamics of fixed-wing flight in the cruise segment, help enable the range and speed involved.

Networking and Collaborating

Joby’s newly-announced office in Washington, D. C. is going to be different.  Visitors will be able to “fly” a state-of-the-art simulator and get a “hands-on” experience different from those often reported in D. C. offices.  Joby hopes to support the collaborative work it’s engaged in with the military and private industry while furthering approaches to eventual commercial certification of its enterprise.

Visitors to Joby’s Washington, D. C. office will be able to control a simulator showing what a ride around the nation’s capitol will look like from a Joby sky taxi

Already a multi-year partner in the Agility Prime program and seeking FAA Part 135 certification, Jody will be well positioned in its new office to sell the ideas and hardware of a new aviation age.  This includes a joint effort with JetBlue Airways and Signature Flight Support to build a pathway to the utilization of electric and hydrogen aviation credits.  Joby explains, “The company is also working with policymakers and local governments to support community-based planning grants for aerial ridesharing as well as the development of electric aviation charging infrastructure.”

Greg Bowles, Head of Government Affairs at Joby,  “We look forward to accelerating the industry’s education efforts on the dramatic benefits that zero-emissions aviation and eVTOL flight enable and we’re grateful for the support of key government and industry stakeholders who have already visited our new DC office and experienced Joby flight in our simulator,” added Bowles. “We look forward to welcoming many more thought leaders and policy makers as we demonstrate the global importance of the clean future of flight.”

Your editor’s personal observations of JoeBen’s approach to managing is that he has a gift for implementing the many steps that lead from inception to realization.  His practical and political steps so far allow us all to look forward to an exciting future.

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The Layered Look in 1000x Solar Cells

We hear a lot about 10X batteries, but 1000X solar cells?  Layering up may be stylish and even practical in the fashion world, and in solar cells may be a chance to unite otherwise dissimilar materials with otherwise limited light-to-electric conversion capabilities.   That strategy produced solar cells with 1000x that.  That’s what researchers at Martin Luther University Halle-Wittenberg (MLU) found when they created crystalline layers of layers of barium titanate (a mixed oxide of barium and titanium), strontium titanate and calcium titanate which they alternately placed on top of one another.

Researchers found high increases in responses from the layered oxides because of higher permittivity – electrons able to flow more freely.

The team’s paper, “Strongly enhanced and tunable photovoltaic effect in ferroelectric-paraelectric superlattices,” appears in the June 2 issue of the journal Science Advances.

A Titanate Sandwich

Barium titanate (BaTiO3 or BTO) is a “common ferroelectric material” used to manufacture electronic components such as capacitors.  It is, “a popular choice for use in capacitors because of its high values of dielectric constant.”  Layering slivers of this material with thin slices of strontium titanate (STO) and calcium titanate (CTO) enabled the otherwise not very reactive BTO to produce 1,000 times its original energy.

Layers of calcium titanate (CaTiO3), barium titanate (BaTIO3), and strontium titanate (SrTiO3)  and their reaction to differeent wavelengths of light.  Structural characterization of superlattices. (A) Cross-sectional STEM acquired from sample SBC222. (B) High-resolution STEM from a part of the scanned region. The schematic depicts the arrangement of unit cells. RSM acquired around (103) reflection in (C) BTO, (D) SBC555, (E) SBC252, and (F) SBC222. Star and yellow arrows indicate the STO substrate and satellite peaks from SL, respectively. Credit: Science Advances (2021). DOI: 10.1126/sciadv.abe4206

The University’s newsletter shares an inside source.  “Yeseul Yun, a PhD student at MLU and first author of the study, explains: ‘We embedded the barium titanate between strontium titanate and calcium titanate. This was achieved by vaporizing the crystals with a high-power laser and redepositing them on carrier substrates. This produced a material made of 500 layers that is about 200 nanometers (0.00000078-inches) thick.’”

That process in turn led to a multi-layered “solar cell” that is “ferroelectric.”  Physicist Dr Akash Bhatnagar from MLU’s Centre for Innovation Competence SiLi-nano explains, “Ferroelectric means that the material has spatially separated positive and negative charges.  The charge separation leads to an asymmetric structure that enables electricity to be generated from light.”

Because of this separation, ferroelectric cells don’t need P and N (positive and negative) junctions.  This eliminates the need for positive and negative “doping” of different layers, and makes ferroelectric cells easier (and presumably cheaper) to produce.

Ferroelectric materials, to be effective as solar collectors, must be alternative with paraelectric materials, that generate dielectric polarizations when an electric field is applied to the material and lose the polarizations when the electric field is removed.  This switching seems to have an effect on the overall ability of the sandwich to generate electricity.

Temperature- and periodicity-dependent photovoltaic effect. (A) JSC extracted from IV characteristics acquired at different temperatures. The inset shows vertically magnified curves for BTO, SB55, and BC55. (B) Extracted values of VOC and σtotal as a function of temperature. (C) JSC measured in different samples at room temperature (RT) and 77 K. (D) JSC measured under 1.5 AM solar illumination at room temperature.

Aeronautically Speaking

Solar Impulse flew on 17,248 photovoltaic solar cells, about 269.5 square meters (2,901 square feet) in area.  They could put out about 66 kilowatts at full power if the sun were directly overhead on a cloudless day.  For an airplane, that condition will rarely be true.

Eric and Irena Raymond’s Sunseeker Duo carries 1,510 solar cells, enough to power its 25 kilowatt (33.5 horsepower) motor and enable all-day soaring flight.  It started with the 25 square meters (269 square feet) wing area of the Icare’ 2 from which the wing was derived.  We’ve reported before that the area was reduced slightly to accommodate the more efficient solar cells available.  Both aircraft fly at bird-like speeds.

Enhancement of photovoltaic effect in tricolor superlattices.
(A) Current-voltage (IV) characteristics measured with 3.06 eV at room temperature. (B) Current-time response acquired with the illumination ON and OFF.

In either instance, solar cells capable of providing even 10 times the power feasible with today’s best would have given Solar Impulse 660 kilowatts to fly faster on a smaller wing – making ocean crossings less of an ordeal.  Rather than flying essentially a sailplane, the Raymonds might make longer, quicker trips in something like a short-wing Pipistrel.  1000x in either case would provide unprecedented power.

Either redesign would require totally different wing, span, and power loadings and would be very different airplanes.  Totally new designs could reduce aircraft size and weight while stretching performance.

Will the cost of these much-improved solar cells be expensive?  Two friends who inquired about flexible solar cells for their electric ultralights a few years ago were disappointed to find the cells cost as much as their airplanes.  We can hope the good people at Halle find a way to make one of those lucrative university-industry partnerships possible in the near future.  Much loke Martin Luther nailing his 95 theses to the Wittenberg door, this would be a true game changer.

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Nine Engines and Two Wings – the DEP Antonov

Sporting no less than nine powerplants, eight of which are electric, a cold-war biplane stunned the crowd at a Russian air show.  Part of the 15th International Aviation and Space Salon MAKS 2021 held on July 20-25, a Siberian adaptation of a Russian classic drew widespread attention.  Your editor has had the privilege of enjoying two flights in the original giant AN-2 biplane powered by a Schwezow ASch-62IR nine-cylinder radial engine with 1000 horsepower.  That engine sounded like a freight train grumbling through the valley over which we flew.  This new version has a 1,100 shaft horsepower Honeywell turbine in the nose and eight motors with folding propellers arrayed along the lower wing.  The sound is futuristic, while the airframe is anachronistic.

Electric-Flight.eu headlines its coverage with, “Russians impress with blown-lift technology on old double-deckers.”  Think of an imposing biplane standing almost 14 feet tall, carrying a total wing area of 71.52 square meters (769.8 square feet) and hauling 12 to 14 fully-armed troops into combat.  Despite its lumbering speed, this must have seemed like a good idea to Soviet military planners, since they had 18,000 built – roughly equivalent to B-24 production in WWII.

The electric motors arranged symmetrically under the leading edge of the lower wing blow across a wing area of only 14.24 square meters (153.28 square feet), but seem to make the five-second takeoff roll a non-event.  Along with a steep climb that would clear trees or other obstructions along a jungle clearing, the airplane would make a great search and rescue craft, or could carry large loads to remote sites.

 A Ninth Decade

Routesonline.com reports, “The Siberian Aeronautical Research Institute, named after S. A. Chaplygin (SibNIA), believes its TVS-2MS turboprop conversion of the classic Antonov An-2 piston airliner could prolong the life of the venerable aircraft into a ninth decade, with Africa a strong potential market for the modernized airplane.”

Antonov showed ability to hang on all nine props during airshow demonstration

As with many Russian aircraft, Antonovs are hell for stout, and the leader at SibNIA knows that the plane is outstanding in its literal field.  “We often talk about point-to-point and regional to hub feed, but the SibNIA TVS-2MS truly offers a field to airport offer to the market and when we say field we do not just mean small rural airfields, it can freely operate from grass strips with its excellent short-field performance.”

Thinking at a more bucolic than urban level, the Institute’s designers see the big bird also levitating from rooftops, fulfilling a mission to perhaps alleviate ground traffic in Moscow and St. Petersburg.  This would require propping up roof beams, of course.

The TVS-2MS, stipulated to land and take off in the same area usually intended for the MI-8 helicopter (30 by 50 meters or 98 by 164 feet), is being followed by the TVS-2DT, a fully composite biplane.  It must clear a 15-meter obstruction at the edges of the “field,” which is not tidily defined.

SIbniA has also crafted the TVS-2DT, an all composite, turboprop version of AN-2

The nine-motor monster will probably not be a production craft, but may presage further, sleeker developments.  An AN-3 lurks in the wings and several concepts await in a hazy future.

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