At least two Cessna 337s are flying on modified power systems – one with Ampaire in various locations around the world and one in France. VoltAero’s French Cessna push-pull twin has been turned into a tri-motor, with twin motors sprouting from the front of the craft’s tail booms. Like its American counterpart, VoltAero’s machine is a test bed for the planned power system that will mark its successor.
VoltAero reveals its coming aircraft will feature a “barrel”-type arrangement of three 60 kilowatt electric motors ringing a central internal-combustion (thermal) engine. Jean Botti, CEO of VoltAero, explains the motor configuration is well-proven, having flown in the Cassio 1 demonstrator (the Cessna) since October last year. Since then, it’s been flown around a series of airports in France, racking up over 3,000 kilometers (1,864 miles) in 10 hops visiting 11 cities.
Later versions of the Cassio design will feature the 330 kW hybrid arrangement of Cassio 1, producing 442 horsepower. Later versions will produce 480 kW (644 hp.) and 600 kW (805 hp.) for the six and ten-seat modular expansions. The latter will cruise at 200 knots (360 kilometers per hour or 230 mph). Each of the craft will feature significantly lower operating costs than fossil-fuel rivals.
At a small gathering on October 21, 2020, Jean Botti let his select audience hear just how quietly his Cassio 1 could traverse the skies over France. The video is a bit long and has lapses common to a live presentation, so follow the timing marks below:
Between 16:50 and 40:30, Botti delivers a presentation on the salient points of his demonstration aircraft.
From 1:15:20 to 1:23, attendees could compare takeoff noise levels between a “standard 337 and the hybrid version: 80 dB vs 72. To enable comparisons, we’ve attached this link.
In the short interval from 1:25 to 1:29:20, both craft fly overhead, again demonstrating a significant difference in sound level.
From 1:32:15 to 1:43:15 the planes land, taxi to the hangar and Botti makes closing remarks.
VoltAero’s comparison of fuel burn for turbine helicopter compared to fuel burn for hybrid system like that on Cassio 1
VoltAero makes several claims for the power system, including:
The dual source of power provides unmatched safety.
4 dBa lower noise than comparable aircraft during operations, and no noise during ground taxi (with an electrically-driven nose wheel). This is low compared to the sound levels demonstrated in the actual flight demonstration.
20 percent lower emissions than comparable aircraft in the full hybrid mode and 100 percent in full electric.
The team has a history and a series of demonstrated accomplishments
VoltAero CEO and Chief Technology Officer Jean Botti and Technical Director Didier Esteyne have a history with electric aircraft, ranging from making a four-motor Cri-Cri that flew at the Paris Air Show to developing Airbus’ eFan range. Their latest effort shows they are willing to explore new ways of electrifying flight.
A new “record” for an electric aircraft flight probably won’t make the books, but was a great sales opportunity for the off-grid charging system that accompanied it.
21 electric airplane records exist in the list of Federation Aeronautique Internationale-recognized achievements. At least one was set in 2012 by Jean-Luc Soullier in his Colomban MC-30 Luciole (Firefly) – 189.87 kilometers per hour (117.98 mph) over a 15 kilometer closed course using a Lynch-type brushed motor. It topped his record in February of the same year of 136.4 kph (84.76 mph).
Jean-Luc Soullier in his record-setting Luciole nine years ago
For a while, Soullier held records for altitude and distance, but these were eclipsed by others. At the time, your editor encouraged beating these records, since they were early efforts in a field that should have shown greater progress that it has. Batteries are not that much improved in some respects.
Recent flights in Australia, Europe, and America required a mobile infrastructure to charge those batteries. Cars, trucks and airplanes carried the charging gear for each flight, but this week’s flight over California’s Central Valley showed another possibility.
BEAM ARC charging station, “topping up” Joseph Oldham’s Pipistrel Alpha Electro and Dennis Wheatley’s Zero electric motorcycle. Unit is portable and can be installed on site in minutes
It’s difficult to quantify the “longest flight ever” for electric aircraft. Eric Raymond did 21 hops across the United States in 1990, kept aloft by solar power. Solar Impulse made it around the world and across the Atlantic and Pacific on sun power.
Joseph Oldham, founder and CEO of New Vision Aviation flew the Pipistrel Alpha Electro, part of a fleet of four owned by the organization. Beam Global CEO Desmond Wheatley was on hand at each stop along the way, explaining the benefits of his off-grid, stand-alone charging stations.
Taking a straight shot up Highway 99 and starting on Wednesday, July 14, the Pipistrel Alpha Electro’s flight left Fresno’s Chandler Executive Airport and headed to Madera Municipal Airport. With two hours for recharging the aircraft, Oldham and Wheatley gave interviews to the local press. Oldham flew on to Madera, Merced, and ended the morning’s ride at Modesto, where the team repeated their interviews with the press, showing off the Pipistrel and Beam’s ARC solar-powered charging station. The early mornings avoided the turbulence likely in the hotter part of the day.
Friday and Saturday saw a reversal of the trip, with a special event for “media and guests” in the early afternoon.
A Qualified Record
Fox 26 reported the return for their viewers. “Beam Global pilot Joseph Oldham has broken the world record for longest flight ever powered only by off-grid renewable energy.
“Joseph Oldham, Founder of Fresno-based New Vision Aviation set the record landing at Chandler Airport.
“The flight was organized by Beam Global to promote the movement towards clean transportation.
Flying early mornings helped avoid turbulence. “(The flight) was smooth,” [Oldham] said after landing. ‘It was nice and cool, and the air was nice and smooth. (It was) just really wonderful.’ Oldham said he is able to fly the aircraft, which weighs about 1,200 pounds and has a wingspan of 36 feet, for about an hour at a time.”
“Beam Global hopes that setting this record proves that zero-emission transportation is possible.”
Heart Aerospace, on the airport at Gothenburg Airport in southern Sweden, wants to bring inexpensive, four-motor electric flight to the masses. With $35 million (29.4 million euros) in recently acquired backing, the small team at Heart is working toward making a 19-passenger, four-motor airliner a reality. Their ES-19 is a single-aisle design with eight-rows of single seats and three-seat row at the cabin’s rear.
Tidy interior features 30-inch pitch between seats. Most airlines feature 29 to 31-inches
Heart sees the 19-seat market as promising, since few 19-seat commuter liners exist anymore. Part of that is economic, with small turboprops being nearly as expensive to run as larger ones. Electric powerplants would lower total operating costs and help restore previously unprofitable routes to more destinations. In your editor’s view, four small electric motors, with controllers, battery management systems and battery packs tucked into each nacelle, could lower total cost and spread aircraft weight along the span. The design allows for “blown lift,” a feature other makers tout for their short take off and landing (STOL) designs.
Mesa Airlines sees new hope for currently unserved communities. “Mesa was the world’s largest operator of 19-seat aircraft and has unparalleled expertise in connecting smaller communities to the national transportation system. Over the past 30 years, as the economics of operating 19-seat aircraft became uneconomic, operators exited markets and practically all 19 seat aircraft have been withdrawn from commercial service. For example, Farmington, New Mexico, a rural community bordering the Navajo Nation, previously had over 30 daily departures to seven destinations. Today, Farmington has no scheduled passenger service. The reduced operating costs of the ES-19 aircraft hold the promise of revitalizing travel options that are currently not economically viable with traditional aircraft.”
Map includes routes Finnair ceded to another carrier, showing need for short-range transport
Similar hopes are expressed for European routes over mountains and across waterways that would otherwise consume hours by bus, car, or boat.
The firm has an obviously talented crew, boasting personnel who’ve worked on over 100 aeronautical projects. Initially, 400 kilowatt motors, controllers, and battery packs will be in-house designed and built. Later components for a more powerful version will be sourced like a popular plastic brick maker’s products. “Moreover, an aircraft is a Lego kit of different components manufactured by different suppliers. Heart Aerospace is working with the same suppliers as the established aerospace companies.”
The pre-prototype being built in-house will be powered by four 400 kW motors each driven by four 180 kilowatt-hour batteries mounted in the nacelles behind the motor and controller.
This craft will have a top speed of 215 knots (247 mph) and cruise at 180 knots (207 mph). It can land and take off on an 800-meter (2,625 feet) runway, common enough on airports for small aircraft. The prop wash over a good percentage of the wing and high-lift flaps will aid in short-field operations.
Overall, efficiencies are high, with propellers returning 88 percent, motors converting 97-percent of current that reaches them to useful power, and motor controllers hitting 99.7-percent efficiency.
Heart explains the economies of operation for their craft. “Our electric motor is about 20 times less expensive than a similarly-size turboprop, and about a 100 times less expensive than the cheapest turbofan. More importantly, maintenance costs are more than 100 times lower. These lower operating costs will make 19-seater electric aircraft competitive to 70-seater turboprop aircraft. ”
Battery packs have an energy density of 200 Watt-hours per kilogram, a credible figure considering ongoing hyperbole in the industry. Almost a given based on the video credits, Northvolt will probably be the supplier. One source suggests Northvolt would supply 4865 cells for Heart’s battery packs (similar to Tesla’s new battery format), but this will need verification.
In an unveiling of the aircraft and its technology, royalty was present in the person of Prince Daniel, Duke of Västergötland and husband to Crown Princess Victoria. Sweden and the Nordic countries in general have a significant interest in promoting clean energy.
Such interest and a viable airplane that could serve regional airports could lead to a clean revolution in a currently underserved part of aviation.
Two companies promoting hydrogen power for aircraft are upsizing their aspirations, with aircraft hauling four to up to 40 passengers. Both have ambitious timelines.
ZeroAvia, operating in Hollister, California and Cirencester, England has been flying a Piper Malibu demonstrator, but anticipates flying a 10 to 20 passenger Dornier by 2024. It would expand that to a 50-passenger craft by 2026. H2Fly in Germany has been flying their Pipistrel-designed HY4 for several years and through six generations. The firm looks forward to taking incremental steps toward a 40-passenger regional airliner by 2030.
ZeroAvia reports on troubling trends in aviation’s contribution to greenhouse gases, but follows with a possible solution. According to their web site, aviation accounts for over 12 percent of total transportation emissions, and may double that by 2050. High altitude contrails mean aviation emissions have two to four times the effect of ground source emissions. Regulators want drastic changes. The European Union mandates a one quarter the CO2 and one-tenth the nitrogen oxides from aircraft by 2050. ZeroAvia is focused on the short haul segment because half of emissions are from flights shorter than 1000 miles.
Short haul segment is most important to address: half of emissions are from flights shorter than 1000 miles. according to ZeroAvia
ZeroAvia’s solution is to create an ever-larger, longer-range group of aircraft to meet transportation needs at every level.
In a two-pronged effort, ZeroAvia is converting two Dornier 228, 19-seat aircraft to hydrogen power. The company reports, “To continue the company’s trajectory toward zero-emission flight, ZeroAvia is ramping up its 19-seat aircraft program to decarbonize and revolutionize regional air travel. The company will utilize two twin-engine 19-seat Dornier 228 aircraft – one in the UK and one in the US, provided respectively by Aurigny (an airline on the channel isle of Guernsey) and AMC Aviation. Both aircraft were previously in service for regional flights in the US and UK, demonstrating the opportunity for carbon reduction on existing routes.”
ZeroAvia’s initial demonstrations using a Piper Malibu were dubbed HyFlyer I. The new phase, HyFlyer II, is part of a program backed by the United Kingdom government to develop a hydrogen fuel cell powertrain. Lessons learned from the first phase will be incorporated into development of a 600 kilowatt powerplant to be used in the 19-seat Dornier.
ZeroAvia’s drive train. Twin units on Dornier 228 will be 600 kW (804 hp) each. We look forward to getting more details on ZeroAvia’s H2 motors, which look different from more conventional electric powerplants
LongTailPipe. com explains, “It looks like immediately behind the propeller is an electric motor, with no gearing between the motor and the propeller shaft. Immediately behind that is what looks like an inverter (motor controller) with cables connecting it with the motor. I’m wondering about the color choices in the wiring harness, since I understood it is required to use orange cables for high voltage wires so that technicians know which cable is dangerous.
“Behind that is a blue box. Might that be the fuel cell stack?
“Besides the motor and the inverter, there are three or four major components that must exist:
“Hydrogen storage tanks — most likely in the wings or where ever the gas tank is in this airplane. (ZeroAvia has a diagram of the H2 tank locations on the airplane, as shown below.)
ZeroAvia Malibu H2 tanks, which take up considerable room
“Fuel cell stack
“Overall system control electronics, as well as avionics in the cockpit
“Small battery pack to buffer energy from fuel cell for driving the motor”
Part of HyFlyer II, the second ZeroAvia-led project backed by the UK Government to target the development of a hydrogen fuel cell powertrain. “As part of HyFlyer I, ZeroAvia successfully demonstrated a 250kW powerplant in a 6-seat aircraft across three flight test campaigns, achieving all the project’s technical goals, including fuel-cell only cruise flight.” Lessons learned from the HyFlyer I program will be incorporated in powering the Dornier 228s.
H2Fly’s 19-seat Dornier 228 will replace the two turbine engines with 600KW units of the company’s hydrogen-electric powertrain. hydrogen fuel tanks eventually holding 100kg of compressed gaseous hydrogen to support the 500-mile range of the commercial offering in 2024. Additionally, ZeroAvia is progressing the software, hardware, mechanical integration, and fuel cell balance-of-plant to the certifiable state. The 6-ton aircraft will have a range of 500 nautical miles.
H2Fly is the outgrowth of work done by Germany’s DLR (Deutsches Zentrum für Luft- und Raumfahrt, or German Aerospace Center). Headed by Joseph Kallo and using the Pipistrel G4 that had won the NASA Green Flight Challenge (sponsored by Google) in 2011. the battery-powered G4 was converted to hydrogen powered HY4 and has gone through six iterations as a test bed for H2 aerial transport since 2016. In one test series, it made 32 takeoffs in four days, showing the ability to refuel quickly. H2Fly reports that since then, “From 4th of November 2020 till 23rd of November 2020 the 6th generation of hydrogen powertrain made over 35 take offs, flying up to 2 hours per flight.”
From that well-tested beginning, H2Fly anticipates flying a series of ever-larger craft. The four-seat Air Taxi, slated for 2025, would incorporate redundant H2 storage, 350 kilowatt (469 horsepower) motors (200 kW or 268 hp. at cruise), and a range of up to 250 kilometers (155 miles) within its 1.5 hours maximum endurance.
By 2027, H2Fly anticipates flying a six-to-19 seat fixed-wing commuter. With 425 kW (570 hp.) full power and 300 kW (402 hp.) at cruise, the commuter can travel up to 1,500 kilometers ( 932 miles) at a maximum cruise speed of 370 kilometers per hour (230 mph). The fixed-wing aerodynamics help achieve excellent range.
This would lead, by 2030, to a 40-seat commuter liner powered by three megawatts (4,023 hp.). One a cruise power of 1.4 mW (1,877 hp.), the liner could fly at 520 km./hr (323 mph) for up to 1,850 km. (1,150 miles).tt
H2Fly’s ambitious plans somewhat mirror those of ZeroAvia’s, and both herald a cleaner future for commercial aviation. With production of “green” hydrogen on a surprising increase and costs going down, future flight may not only be cleaner, but less expensive.
Phinergy, an aluminum/air battery maker from Israel, is now partnering with Indian Oil Corporation. Phinergy’s technology just received an award from the World Economic Forum as one of the 100 most promising Technology Pioneers for 2021. Phinergy was chosen for, “Its innovative energy solutions which turn metals, such as aluminum and zinc, into a clean, sustainable and cost-effective means of storing, transporting and generating energy.”
Phinergy battery in Leaf EV. Several more under the trunk floor belie the appearance of the single pack in this picture.
Why would Indian Oil Corp. (biggest oil outfit in the country) be attracted to Phinergy and its aluminum/air batteries? Company R&D Director S.S.V. Ramakumar explains, “Lithium is scarce in the country and we started scouting for an element which is abundantly available as a natural resource.” Unspoken, the idea that India has one of the most polluted airsheds in the world, means increasing pressure on Big Oil to redeem itself. Reuters reports, “India was home to 35 of the world’s 50 most polluted cities, according to IQAir’s 2020 World Air Quality Report, which gathered data for 106 countries. The findings were based on the country’s annual average of particulate matter PM2. 5, airborne particles with less than 2.5 microns in diameter.”
Typical of “Tuktuks” that clog Indian cities, Mahindra Treo has lithium-ion battery – could benefit from aluminum-air replacement. Two-stroke powered Tuktuks are a huge source of pollution
A possible solution to India’s air woes could be their 600 million tons of bauxite ore, enabling India to be one of the top 10 bauxite producers. That U.S. Geological Survey estimate may be eclipsed by India’s mining ministry appraisal that untapped resources may be many times that amount. Even at current production levels India is the world’s second largest smelter of aluminum.
As Steven Loveday reports in InsideEVs.com, “Reportedly, these aluminum-air batteries are very energy-dense, which means even in a much smaller and lighter package, they’ll be able to provide significantly more range. They’re also cheaper and safer than lithium-ion batteries.”
One major problem remains. Aluminum-oxygen batteries can’t be recharged, at least in the bounds of current technology. Suppliers will need to set up some network of battery swap stations, where a high-speed system could drop out the spent batteries and replace them with newly-minted ones. Even though one could drive from San Francisco to Los Angeles and back on one charge, the need to find a specially equipped swap station may dissuade potential users. Swappability might not be a problem for aircraft, especially if the battery packs were similar to those on Pipistrel’s Electros.
Nikki Gordon-Bloomfield of New Zealand’s Ecotec shares a possible solution in the following video – the Aluminum-air battery acting as a range extender for a vehicle’s lithium-ion pack.
Aluminum-air batteries can be less expensive than their lithium equivalents, give better range, and be safer. Just the freedom from worrying about flammability might be reason enough to choose aluminum-air. Their energy density is excellent, and in this seven-year-old video, Phinergy demonstrated the ability of the single stack of aluminum-air cells to drive a small Citroen over 300 miles.
Green Car Reports reported on CEO Aviv Tzidon’as comments about this demonstration. “Each aluminum plate, says Tzidon, has enough energy capacity to power the car for roughly 20 miles (we’d guesstimate it at perhaps 7 kWh), and the test car has 50 of those plates. The entire battery, he says, weighs just 55 pounds (25 kilograms)–apparently giving it an energy density more than 100 times that of today’s conventional lithium-ion pack.” That sounds pretty spectacular, and it would seem the world would have beat a path to Phinergy’s door before this. Let’s be a bit skeptical, but hopeful. The backing from a huge Indian firm may be what Phinergy has needed all along.
Israel’s Eviation has moved its manufacturing resources to Arlington, Washington, north of Seattle. There, they are making an all-new version of Alice, changing its configuration from “V”-tailed to “T”-tailed and its power from tri-motor to bi-motor.
Alice over Seattle, near its new build site. magniX provides newly-developed twin motors
The revised craft will be powered by two Magni650 power units, a package that includes a 640 kilowatt (850 shaft horsepower) motor, four magniDrive-100 inverter/motor control units, and “a closed-loop integrated thermal management system.”
A New Alice
Charles Alcock, reporting in FutureFlight.aero, says Eviation Aircraft confirms plans to make a first test flight of the redesigned craft by year’s end and have the new Alice certified and entering service in 2024.
Obvious changes include a clean, high-aspect ratio wing and pylon-mounted motors flanking the “T” tail. According to Alcock’s report, a company spokeswoman explained, “We moved from a V-tail to a T-tail to optimize performance and handling and make it easy and reliable for pilots to seamlessly transition to flying the aircraft.”
Now considerably different from original concept, new Alice loses one motor, changes configuration completely
Two crew members will fly (and probably host) the “up to nine” passengers on trips up to 440 nautical miles (506 statute miles or 814 kilometers) at speeds “just over” 250 mph (402 kilometers per hour). Numbers are lower than previous specifications (748 statute mile range, 299 mph cruise), but still viable for regional flights.
The original design had an 820 kilowatt-hour battery weighing 8,200 pounds or 3,719 kilograms – 60-percent of the craft’s maximum takeoff weight. That would be only 49 percent of the current design’s 16,500 pounds. Passengers account for 2,400 pounds in the current design and the two motors 440.9 pounds (200 kg.) each. That leaves 13,218 pounds for propellers, two crew members, airframe and batteries. Counting the loss of one motor (let’s say 500 pounds with propeller), one wonders how the weight is built up in the current version.
Since its original prototype was destroyed in a ground-power-unit fire at its test site in Phoenix, Arizona, Eviation has evidently been modifying its original design to the version we now see. It has also moved its operations to several hangars at Arlington airport in Washington State, where it’s spent “at least” $300,000 renovating the buildings. Motor-maker magniX is only 14 miles away in Everett, also home to Boeing.
AIN reports, “In May, MagniX delivered the first Magni650 EPUs to Eviation. Singapore-based Clermont Group owns the two companies.” With Pacific-based ownership, it’s interesting the two companies are united in the same aeronauticially-rich region.
Airframer.com reports, “magniX has announced details of its magni350 and magni650 Electric Propulsion Units, the latest advancements of the company’s flight-proven EPU product offerings.”
magni650 EPU comprises dual motors, four inverter/controllers
Earlier versions have undergone thousands of hours of ground and flight testing. These latest versions are “optimized for real-world commercial aviation applications to further accelerate the path to certification for electric aircraft and bring the future of electric aviation closer to reality.” Having flown in Harbour Air’s eBeaver and an eCaravan, the motors have been simplified and “enhanced.”
The magni650 can be seen as two 350s joined to power a common nose cone propeller drive. The 350EPU, controlled by paired magniDrive-100 inverter/motor controller power electronics units, is doubled in the 650EPU, with four 170 kilowatt magniDrives enabling high redundancy and the ability to maintain partial power despite loss of any unit. Liquid cooled the direct-drive EPUs can manage 30,000 feet in unpressurized environments. The front cone can accommodate a propeller governor and all standard aircraft accessories.
magniX EPUs operate at 2,300 rpm or less, generating high maximum torque of 3,200 Newton-meters (2,360 foot-pounds) and nominal torque of 2,820 Nm (2,080 foot-pounds).
Other Supporting Players
Eviation’s Alice receives parts at its Arlington location from 11 different nations. Honeywell Aerospace provides Alice’s fly-by-wire flight control system, for instance.
Other key program partners announced so far include Honeywell Aerospace, which is providing the Alice’s fly-by-wire flight control system, and aerostructures group GKN Aerospace. On June 3, GKN said that it has delivered the first fully integrated wings, empennage, and electrical wiring interconnection systems for the aircraft from its facility at Bristol in the UK. Perhaps manufacturing will move to Washington state also, since GKN has a site in Sumner, Washington that produces winglets for Boeing 737 Max’s and parts for F-35s.
Roei Ganzarski, CEO of magniX and Executive Chairman of Eviation, has high hopes for his products. “Based on real-world design, build and operational testing, we’re making incredible strides to push the aviation industry forward and accelerate the rate at which aircraft become electric. The magni350 and magni650 EPUs enable affordable, emission-free and quieter flights to communities around the world in the very near future.”
Eviation CEO Omer Bar-Yohay is equally enthusiastic. “Sharing our production Alice design is a special day for Eviation and our partners. Electric aviation will continue to open up new possibilities for affordable, sustainable regional travel around the world. Alice is poised to turn that possibility into a reality soon.”
Car fires are scary. Airplane fires are even more so, since you can’t just pull over and hop out. Scientists at the National Renewable Energy Laboratory (NREL) and NASA, and in England and France may have come up with a way to stop electric car fires. Owners of petrol-powered autos will have to continue to check for leaking flammable fluids, greasy engines, and sources of the 140,000 car fires in the US alone every year.
There aren’t that many electric car fires, but they make the news. One in particular, a brand new, low-mileage Tesla S Plaid, melted down after self-igniting. Reportedly, the $130,000 car briefly trapped the owner inside.
The Verge reports, “Luckily, the driver escaped alive. It’s also important to note that this could be a flaw with the design, but further investigation is necessary to confirm or refute this possibility.”
A headline fire like this draws headline legal attention – in this case from Mark Geragos, already famous for his defense of celebrities and criminals such as Michael Jackson, Winona Ryder, and Scott Peterson. Geragos made a strong statement regarding the fire and the Tesla. “This is a harrowing and frightening situation and an obvious major problem. Our preliminary investigation is ongoing, but we call on Tesla to sideline these cars until a full investigation can occur.” His client incidentally owns $1.1 billion of Tesla stock.
Cooling Things Down
Stakes are obviously high when a major stock holder’s attorney wants to shut down a profitable car line. Luckily, there may be a fix for Tesla’s and other EV makers’ headaches. The NREL and NASA, “worked with a global team including University College London, The Faraday Institution in Oxford, National Physical Laboratory in London, and The European Synchrotron in France.”
Controlled nature of experiment protects researchers from flareups during nail penetration tests. Amateur experiments are often spectacular, but not shown here to discourage imitators
NREL, et als’ work seems similar to that done by Eric Darcy (Battery Systems Technical Discipline Lead at NASA-Johnson Space Center) five years ago. His design of battery packs for space suits allows no room for even a little smoke, and requires utter reliability.
Polymer-lined current conductor stops spread of thermal reaction, enables current to maintain original values
In the NREL tests, 18650 (18 millimeters in diameter by 65 mm in length) lithium batteries were placed in a specially-designed holder. This was probably necessary because the puncture tests being performed often set off strong reactions in the highly reactive lithium cells. Even when not “in action,” lithium batteries can be dangerous if damaged or overcharged.
A 100-Percent Solution
Most heartening, the researchers are able to asset that, “Cells with aluminum-coated polymer current collectors demonstrated 100% success in thermal runaway prevention during nail penetration….” The test cells retained a cell voltage >4.00 V, while standard cells consistently experienced thermal runaway.
Polymer substrate current collector “retreats” from short circuit, preventing thermal runaway. Normal copper or aluminum conductor without polymer would encourage spread
Copper or aluminum current collectors are part of most cylindrical cells and deliver energy between the anode and cathode. When a cell is punctured, the metallic collector forms a circuit between the elements in the call and promotes a short circuit. In turn, that leads to thermal runaway in the cell itself. In a battery pack, the explosion of one cell can trigger the others, somewhat like lighting a string of firecrackers.
The polymer current collectors form a barrier to further “short circuiting.” The paper’s abstract explains this reaction. “The principle of the PCC safety mechanism is that the initial heat generation caused by the short circuit causes thermal degradation and thus the PCC periphery to shrink away from the nail, breaking the short circuit and preventing thermal runaway.”
Changing the current collector in a “Tootsie Roll” cylindrical battery cell would not seem to require changes in manufacturing systems, but merely the change of one material on one roller. The same materials may substitute for current collectors in pyramidal and pouch cells. This may be very good news for battery makers and the public that needs to trust its EVs and electronic devices.
A three-pilot crew accompanied by a five-person, multi-vehicle support crew have set a world endurance record for electric flight. The team traversed 1,350 kilometers (839 miles) over not-always-hospitable terrain and through not-always-welcoming weather. Participants in the record attempt held up admirably, with few problems other than seemingly constant cross-wind landings and often uncooperative weather.
Their flight made it onto Australia’s largest television network.
Eyre to There Managing Director Barrie Rogers explains the limitation of the aircraft and the effect this had on the flight. “The Pipistrel Alpha Electro – dubbed the ‘Tesla of flying’ – currently has a flight time range of about 1 hour and cruising speed of 85 knots (157km/h) so we’ve had to very carefully plan each stop and build in contingencies for weather such as strong head winds.”
The craft itself shows the characteristics that make it a good trainer – but probably not one’s choice for a world endurance record. The 10.5-meter (34.5 feet) span Alpha carries a maximum of 550 kilograms (1,212.54 pounds), putting it in Light Sport Aircraft territory. Remember, t00, that the weight doesn’t go away as the motor drains electrons, so landings and takeoffs are equally heavy.
As noted, it makes a great in-pattern (“in-circuit”) training aircraft, but range limitations keep the Alpha Electro from striking out for distant realms. To help overcome that, the South Australia flight acts as a reconnaissance project. Barrie notes, “The flight will also investigate suitable airfields along the route for the introduction of electric aircraft charging infrastructure into the future. Eyre to There Aviation plans to prepare a report for the State Government outlining the regional potential for upgraded charging infrastructure in support of current and emerging electric aircraft capabilities. This includes a combination of plane and electric vehicle charging where applicable.”
Even though Alpha Electro’s cruise duration of one hour with a 30-minute reserve limits it practical range to 75 nautical mile (139 kilometers or 86 statute miles), people like Joseph Oldham in Fresno, California are fielding four Alpha Electros to make short cross-country flight among a group of participating airports – all of which are being equipped with charging stations.
Alpha Electro with support vehicles. It took careful planning and precise navigating to find that strip!
Dan Johnson provides another perspective. ” While a strong and notable effort, the attempt and the support it requires puts battery-electric propulsion in perspective. Several current, gasoline-powered Light-Sport Aircraft could fly the entire 1,150 kilometer distance on a single tank (or tanks) of fuel without any need to stop and with no support crew.
“Let’s be fair: Electric airplanes are relatively new and they will only get better. It is not reasonable to expect them to perform equally with fossil-fuel-powered aircraft that have been developed over many decades and with billions of dollars invested to help them achieve the high state-of-the-art they possess today.
“Yet what this observes once again is that batteries are the weak link in the electric propulsion chain. Energy contained in batteries is a small fraction of that contained in a similar volume or weight of gasoline. That gap is narrowing but the pace seems glacial compared to forecasts of electric enthusiasts. Battery improvements of a few percentage points per year means decades before batteries match fossil fuel in energy per pound.”
avPlan EFB flight plan for June 25
Michael Coates, Master Distributor for Pipistrel USA, is an Australian by birth. For comparison with this week’s record, he flew from Brisbane, Australia to New Zealand in a Pipistrel Sinus, roughly equivalent to the Alpha, but heavier and faster.
Landing at Lord Howe and Norfolk Islands along the way, he delivered the plane to Kerikeri Airport after flying a total of 1,523 statute miles in three hops during the 2006 overwater journey. Gas was available at all airports.
His final report: “Total distance travelled, 2452.5 km, total flying time 12:47:23, average fuel consumption in 11.2 [liters per hour] (or 2.95 U. S. gallons).” (Not a world endurance record.)
The three Alpha Electro pilots brought an enormous blend of skills and experience to the project.
Barrie Rogers, Managing Director of Eyre to There Aviation, said, “It’s been a mammoth effort by everyone involved to achieve this incredible feat.” On his Linked In page, Barrie explains, “My company specializes in disruptive Aviation Technology in the fields of Electric Aircraft and the emerging E-VTOL capability.” There are hints that he may take part in manufacturing Pipistrels in South Australia.
David Bradshaw works with GHD Pty. Ltd., a large engineering, environmental, construction firm. He specializes in airport design and defense concerns. This trip would possibly benefit future planning in the region.
“Cath busy crunching numbers for the next few legs. Heading into station country from here: so much more challenging than that faced by the German team last year. AvPlan making the many changes, permutations and “what ifs” easy to compute and compare. Good spread for breakfast too!” Photo from David Bradshaw’s Facebook page
Catherine Conway OAM: The Medal of the Order of Australia is awarded for achievement and service of merit by the Australian Prime Minister. Catherine has served her country in many capacities for over 30 years and is now Operations Manager at Airborne Research Australia. The non-profit organization, “probing the environment using the least intrusive and cost-efficient state-of-the-art airborne technologies .” She is also an accomplished sailplane pilot.
Since electric aircraft “records” are a recent phenomenon, there seems to be some confusion as to what constitutes a record. As shown in Michael Coates’ flight, the range allowed by gasoline is still “miles ahead” of that offered by batteries. Electric aircraft records still fall short of those for fossil-fuel propelled craft. But “conventional” aviation has been here for 118 years, and recreational craft often seem stuck in the 1930’s. With promised battery development, or a radical shift to hydrogen power, electric aircraft could be ready for their own golden age.
Amidst stage smoke and Hollywood-style dazzling lights, Archer Aviation “flew” its Maker into public view two weeks ago. On an immersive cinema platform in a hangar in Hawthorne, California, Maker emerged amid all the pounding two drummers could produce. It seemed to hover above the varied scenery over which it appeared and the on-stage and on-screen special effects were special indeed.
The cynosure of the hoopla, however, was strangely static, even though its guiding lights were highly animated. Co-founders and Co-CEOs Brett Adcock and Adam Goldstein performed flawlessly in promoting their creation, adding to the professionalism of the event. Since the event was inside, and the crowd was allowed to come on stage under the rotor blades, it was probably prudent to have the motors raised and inactive.
Less static in this Computer Fluid Dynamics (CFD) rendering, the Maker displays the flow around its 12 rotors in vertical flight. Since battery tests are underway, perhaps soon we will see Maker taking flight. Then we can make genuine comparisons with Joby’s machine and Beta’s Alia.
The craft carries 74 kilowatt-hours of Meru battery energy, about equal to an early Tesla S. Its 12 motors can generate a maximum of 672 kilowatts (900.8 horsepower), or about 56 kW (75 hp.) each. The amount of battery energy would be used up in about six minutes, though, at full power. This would indicate a flight path that would rise quickly and transition to forward motion and aerodynamics for the quick mission. We will need better batteries – and soon.
Archer’s Maker fuselage with systems. GNSS stands for Global Navigation Satellite System – an all-encompassing set of NAV systems that include GPS. Red stacked boxes represent battery system
Competition and Litigation are Heating Up
Is it just me, or are a great many of the growing crop of eVTOLs looking somewhat similar, like the front-runners in a beauty pageant? It’s often hard to see subtle differences between designs, some of which may be hidden in software or firmware. Those similarities, though, have led to a lawsuit from Wisk against Archer. eVTOL News reports, “On April 6 of this year, Wisk Aero filed a lawsuit against Archer, alleging theft of intellectual property and trade secrets, stating that three outgoing Wisk employees downloaded significant amounts of data from its servers prior to resigning and leaving the company for Archer; Wisk noted, in particular, the similarity of its as-yet unbuilt design filed in a January 2020 patent application and the Archer design ”
In the meantime, the growing number of firms lofting eVTOLs grows, but competition will winnow the crop and we will probably end up with a limited number of builders with the financial and engineering resources to press on.
An Australian flying school and a flight planning software enterprise are in the middle of a series of flights that attempt to break an electric aircraft world endurance record.
The cleverly-named Eyre to There Aviation announces that, “In partnership with platinum sponsor AvPlan EFB will aim to break a world endurance record for an electric aircraft with a 7-day, 18-stop flight around South Australia.”
David Bradshaw awoke to winter morning Down Under. “Beautiful morning, but will have to de-ice the aircraft before we get going. Start of day 3 of our World record attempt.”
According to the organizers, “The proposed route will include flying across to the Lower Eyre Peninsula and inland back to Port Augusta for flight sectors around the Yorke Peninsula before arriving back in Adelaide, subject to aircraft performance and weather.”
A 1,150 kilometer (714.6 mile) trek, the flight would “shatter the previous record of 750 km (466 miles) flown in September 2020 in [Switzerland and] Germany.” The Europeans needed 11 stops for recharging on their trip, so the 18 planned by the Australians is comparable for the planned distance.
Aviation vlogger Stefan Drury hopped a ride in Eyre’s Pipistel Alpha Electro, the only certified electric flying machine in Australia at this time. That may come as a surprise to regular readers, because three years ago we reported on the flight training operation in Perth run by Joshua Portlock and his associates. The team at Electro.Aero gave up training flights to concentrate on aircraft chargers, a business that will become an increasingly necessary part of electric flight. In fact, 93-0938, the aircraft featured in our blog entry on Joshua’s flight school, is now flying in Adelaide for Eyre to There.
Like the Switzerland to North Sea journey, the 18 stops for this record attempt are range limited by the battery endurance of the Pipistrel Alpha Electro. The Europeans had the advantage of flying the newer Velis, with liquid-cooled powerplant and batteries.
Organizers describe the support needed for the record flight. “The flight team and support crew will include three pilots, five on-the-ground support crew, a second support (petrol-powered) plane, and two vehicles carrying recharging equipment for the aircraft.
Support vehicles for south Australia record attempt. Large generator on trailer makes visual counterpoint to efficiency of Alpha Electro
“’The world record we’re seeking to break is basically an endurance record to push the durability and reliability of the aircraft. We’re also hoping to break a couple of other records including fastest point-to-point single flight and fastest climb rate,’ [Eyre to There Managing Director] Barrie [Rogers] says.”
Starting at Parafield Airport on Saturday, June 19, the little Electro few to Balaklava, then to Snowtown, Port Pirie, and the first night’s stopover at Whyalla. Apparently, a Cessna 182 carried necessary charging gear, much like Gabriel DeVault’s journey in his e-Gull and the Swiss/German team’s longer trek in a Pipistrel Velis Electro. As electric aircraft gain popularity, expect the charging network to grow.
Moving map (doubtless running AvPlan EFB – Electronic Flight Bag software) shows flight nearing the end of 27-mile open-water crossing – probably the record so far.
“Day two, leg one. Just completed what is almost certainly the longest over water transit in a certified electric aircraft in Australia, and possibly the World. Chuffed little Vegemite!!” (Ate a substance that according to its ads, “Tastes Like Australia!)
The second day included flight into a desolate land with little vegetation, let alone Vegemite. The crew was met with great enthusiasm along the way, though.
“Day 3, stop 2: Rosevale, near Ungarra, Eyre Peninsula. What a wonderful reception from the local community, including the entire student body of Ungarra Primary School.”
Now into their fourth day of the seven-day adventure, the group presses on. We will report at the end of the week on the overall results of this tour of southern Australia.