Another Combined Motor-Controller System

Compact Dynamics, a German electronics firm associated with MAHEPA, the green aviation consortium, has developed two types of electric motor-controller combinations adaptable to aeronautical use.  Their Dynax® Transversal flow machines and Dynadyn® Radial flux drives integrate power electronics with the motor.

Dynax MGi25-48 combines motor and controller in one compact unit

Their Dynax MGi25-48, one of two lower-power motor-controller combination, is rated at 25 kilowatts (33.5 horsepower) maximum power at 58 Volts, and 20 kW continuous output.  The small motor can generate an impressive 75 Newton-meters (58.3 foot pounds) of torque from its 14 kilogram (30.8 pound) heft.  Even with its controller mounted atop, the full motor package is only 318 millimeters (12.5 inches) high, and 233 mm (9.17 inches) deep.  The motor itself is only 107 mm (4.2 inches) thick.  Its 10,000 rpm top speed obviously requires a propeller speed reduction unit for best efficiency.

A higher-voltage model, the MG40-400, apparently under development, will operate on 300 to 415 Volts, and put out 40 kW (53.6 hp.) from 350 Volts.  The motor weights 10.2 kg (22.44 pounds), but the controller adds 5.6 kg (12.32 pounds).

MG-40-400’s compact dimensions

Compact Dynamics’ Dynadyn radial-flux motors are more powerful, and a bit thicker than their lower-power cousins, but still compact and light weight, each weighing 13 kilogram (28.6 pounds) with integrated controllers.  The Dynadyn 75 has a maximum 75 kW (100.5 hp.) and 25 kW (33.5 hp.) continuous output: the Dynadyn 85 achieves 86 kW maximum and 55 kW (73.7 hp.) continuous power.  They generate 69 and 79 nM (50.9 ft-lbs. and 58.3 ft.-lbs.) of torque, respectively.  They weight 5.8 and 6.6 kg (12.76 and 14.52 pounds), respectively.

Dynadyn 75 motor-controller provides high torque, high efficiency

All motors are liquid cooled and are “Characterized by a very low moment of inertia and high dynamics. With the high power density and low weight there are different options for use of the Dynadyn®-drives in motorsports or aviation.”  All use CAN protocol and can be adapted for various applications with a number of options.  Prices will probably reflect those for those for the 500e drive system for Formula Student teams, 9,000 euros for a 42 kW (56.3 hp.) motor-controller combination.

Certainly, the motors have characteristics that can be adapted to aircraft use, and the company claims that it will produce configurations that suit client’s individual requirements.  These are similar to the Qinetix motor outlined here a few weeks ago.  It’s nice seeing competitive forces rising in the electric aerospace market.

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Pipistrel, itself flying pure electric and hybrid aircraft, has announced its participation in MAHEPA, a Modular Approach to Hybrid-Electric Propulsion Architecture.  MAHEPA aims to,” reduce the gap between research and the production of low-emission propulsion technologies that would enable the achievement of environmental objectives in the field of aviation by 2050.”  Mahepa’s first meeting, held May 15 and 16 at Pipistrel’s headquarters at Ajdovscina (Slovenia), helped define the direction for a major academic/industry project.

Led by the aircraft manufacturer, in cooperation with Compact Dynamics, DLR (Germany’s equivalent of NASA), the University of Ulm, H2Fly, Politecnico di Milano, TU Delft and University of Maribor, project goals are impressive. – “To boost research in the field of low emission propulsion technology to open up possibilities for series production of greener airplanes in order to support European environmental goals in aviation.”  This will result in “novel, modular and scalable hybrid-electric powertrains capable of running on alternative fuels or on hydrogen with zero emissions.”

Taurus Electro was first production electric motorglider in 2007

Pipistrel would seem to be an ideal anchor point for such research, having flown its first electric aircraft, the Taurus G2 self-launching motorglider 10 years ago.  Combining two fuselages and outer wing panels from G2s with a specially-constructed center section and motor mount, the battery-powered G4 won the NASA Green Flight Challenge sponsored by Google in 2011.  After a brief retirement, the airplane was resurrected as the HY4, a hydrogen-fueled, long-range tourer that could be the genesis for aerial inter-urban taxi services.

Mahepa’s approach will to build two high-efficiency, low-emission, series hybrid-electric drive designs, one running a relatively conventional fossil-fuel powered setup, and the other a hydrogen-based drive system.  Both versions will operate with a common control module programmed to provide optimum use of each craft’s energy.  Each partner will contribute its expertise in propulsion, energy storage, and aerodynamics.

Model HY4 at Hanover trade show with representatives who will also be part of MAHEPA

Compact Dynamics, for instance, makes electric motor and controller combinations, small, light-weight packages that live up to the company’s name.  The University of Ulm has ongoing research projects in energy conversion and storage, Autonomous mobility, and sensor technology and signal processing.  DLR, the German Aerospace Center, will doubtless provide oversight in many technologies and protocols that will come from this project.  The University of Ulm, performing research in related areas such as autonomous driving and sensor technology and signal processing, can supply insights into how these craft will navigate and (in a highly technical way) see and be seen.  H2Fly is developing the “sky taxi” model on which routes and on-demand services will be developed.  Politecnico di Milano, through previous research on the Skyspark electric airplane, is well-positioned to add valuable insights.  TU Delft has a long history of research in renewable energy, aerodynamics, and control of drones.  The University of Maribor brings together a variety of disciplines in its IOT – Innovative Open Technologies program.  Together, this amalgamation of knowledge and talent should produce a world-class outcome – and “the development of new commercial, low-emission and highly efficient aircraft.”

This project should expand Pipistrel’s demonstrated skills in producing commercially viable small aircraft, show the way toward more flexibility in how we power our aircraft in an efficient and clean way.  From the small airplanes used for investigating the two approaches, the group hopes to make conclusions leading to megawatt hybrid propulsion systems and a future for bigger, better, and greener aerial adventures.  All projects will strive for a Technology Readiness Level (TRL) of 6, having been demonstrated in its intended working environment.

Technology Readiness Level table used to indicate status of new technology

The project notes broader outcomes: “Within MAHEPA not only new technologies will be developed, but also regulatory implications, airport infrastructure requirements, airspace procedural practices, operational safety, operating costs and emission models will be studied resulting in a unique outlook for regulators, aviation industry, operators and investors.”

The public will get a first look at MAHEPA’s efforts at the Paris Air Show between June 19 and 25, 2017.  Pipistrel’s CEO, Ivo Boscarol predicts, “Hybrid-electric propulsion will change the way we travel. Pipistrel flew the world’s first two seat electric aircraft more almost exactly ten years ago. Since, battery performance has more than doubled, but the near future long-range flight will be enabled by a combination of batteries and range extending technologies. In project MAHEPA we are contributing to the development of two different four passenger aircraft which will be thoroughly tested in flight. This alone is a historic milestone, but with the envisioned scalability of hybrid electric propulsion technology we will soon see much larger environmentally friendly aircraft capable of flying 19 or more passengers across practical distances.”

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University of Houston physicists think they may have overcome the last hurdle to generating abundant hydrogen, a fuel that is as elusive as it is clean.  Their new catalyst, “composed of easily available, low-cost materials and operating far more efficiently than previous catalysts,” could solve at least one of the problems associated with generating and storing H2.

Jeannie Kever, writing for the University newsletter, reports Paul C. W. Chu, TLL Temple Chair of Science and founding director and chief scientist of the Texas Center for Superconductivity at UH and colleagues physicists Zhifeng Ren and Shuo Chen, have created a catalyst “Cost-wise… much lower and performance-wise, much better.”  The quote comes from said Zhifeng Ren, M.D. Anderson professor of physics and lead author on the paper. The catalyst has operated more than 20 hours and 10,000 cycles in testing.

Other researchers involved in the project include postdoctoral researchers Haiqing Zhou and Fang Yu, and graduate students Jingying Sun and Ran He.

Illustration shows procedures for growing ternary molybdenum sulfoselenide on the porous foam; b-c, images showing surface roughness of the nickel diselenide foam grown at 600 degrees C; d-e, morphologies of ternary molybdenum sulfoselenide particles on porous foam, grown at 500 degrees C.

Their paper, “Highly active catalyst derived from a 3D foam of Fe (PO3)2/Ni2P for extremely efficient water oxidation,” published in the Proceedings of the National Academy of Science, explains that their catalyst is made of ferrous metaphosphate grown on a conductive nickel foam platform.

Common and not Noble

The ability to use common materials rather than the noble metals (such as iridium, platinum, or ruthenium) usually associated with such catalysts helps keep costs low.  Ren explains, “In this work, we discovered a highly active and stable electrocatalyst based on earth-abundant elements, which even outperforms the noble metal based ones.  Our discovery may lead to a more economic approach for hydrogen production from water electrolysis.”

Testing determined that the hybrid catalyst required 69 millivolts from an external energy source to achieve a current density of 10 milliamps per square centimeter, which the researchers said is much better than many previously reported tests. In this case, the current “splits” the water, converting it to hydrogen at the cathode. Achieving the necessary current density with lower voltage improves energy conversion efficiency and reduces preparation costs.

UH reports, “A platinum catalyst required 32 millivolts in the testing, but Ren said ongoing testing has reduced the hybrid catalyst requirements to about 40 millivolts, close to the platinum requirements.

“Testing determined that the hybrid catalyst required 69 millivolts from an external energy source to achieve a current density of 10 milliamps per square centimeter, which the researchers said is much better than many previously reported tests. In this case, the current “splits” the water, converting it to hydrogen at the cathode. Achieving the necessary current density with lower voltage improves energy conversion efficiency and reduces preparation costs.”

Splitting water into hydrogen and oxygen requires two separate reactions, each requiring a separate electrode.  One produces a hydrogen evolution reaction and the other an oxygen evolution reaction.  Both reactions are necessary to produce the desired hydrogen.  The primary byproduct “when clean energy is produced,” is water from the recombining of oxygen and hydrogen.  Hydrogen, however produced, can be easily stored, according to the researchers.

Most hydrogen is currently produced through steam methane reforming and coal gasification.  Thus, there are carbon offsets for the clean energy produced by burning the hydrogen, sometimes reducing H2’s desirability.  Other methods involving solar-powered water splitting, have been tried, but are too inefficient, according to Houston researchers.

An Alternate Approach

Daniel Nocera, formerly with Harvard University, and now with the Institute of Chemical Technology (ICT) in Mumbai, India, worked with Pamela Silver of the Harvard Medical School to create an “artificial leaf.”  The leaf used sunlight to convert water to hydrogen and oxygen, reportedly more efficiently than real leaves could manage.  He became disenchanted with the slowness with which new developments such as his gained financial backing in America, and left for India.

He thinks a “renewable energy revolution will take place” in the country.

“I have no doubt about it. The revolution in renewable energy will happen in India. When you look at places in the developed world like the US, you are looking backwards, meaning that’s what it used to be like (coal, oil and gas) and the emerging countries have a decision to take: Do they want to build something looking back or do they want to do something different?

Whether the big breakthrough in H2 production comes from America or India, the benefits will be universal.  Challenges still await those who want to tackle the problems of packaging and distributing the cleanest of energy sources.

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Cartivator, a startup with seemingly boundless energy and endless ideas, hopes to use its Skydrive single-person “flying car” to light the Olympic flame in 2020.  The compact vehicle, claimed to be the smallest flying car in the world, is a tricycle which can traverse roads efficiently.  When confronted by hazards or traffic jams, it can lower its propeller guards and hop over the inconveniences along the way.

Toyota volunteers conceived and are building Skydrive “flying car”

Cartivator Resource Management (CRM) describes itself as “mainly young engineers and venture parties” volunteering, “To carry out the development of the flying car” with the aim of lighting the torch at the Tokyo Olympic Games and Paralympic Games opening ceremony of 2020.  The team pledges, “We will work to accelerate the further technology development.”

One of Cartivator’s promotional videos shows a couple using the vehicle to dodge fallen trees, narrow roads, and allow grandma to visit the grandkids in a distant valley.  Rural roads in Japan are tough going.

The second gives a brief overview of Cartivator’s development and ends with a vision of the planned flight to start the Olympics.  The height reached in this video seems greater than the 10-meter ceiling stated by the designers.

At 2.9 meters (9.5 feet) in length, the Cartivator Skydrive is 1.3 meters (4.26 feet) in width and only 1.1 meters (3.6 feet) high, looking beetle-like as it zooms along a roadway at a target speed of 150 kilometers per hour (93 mph).  This would seem pretty exhilarating for the driver, with his or her posterior only inches above the asphalt.  In flight mode, Cartivator is relatively sedate, moving at a maximum of only 100 kilometers per hour (62 mph).  No weight is given.

The web site lists three features, including the vehicle’s small size, its ability to take off from a public road, and its ability “to be controlled by intuitive operation.”  The latter will be a great leap forward, since many of the team’s videos show their creation flipping over or crashing.  Maintaining stability in flight is obviously not a trivial pursuit with these machines.

Having managed early phases through crowd funding efforts, the group recently received a 40 million yen ($274,000) contribution from Toyota Motors.  That should spur the team to even greater acceleration of their technology development.

We wish the group well, and look forward to a spectacular opening for the 2020 Olympics.

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Imagine a battery that reduces the overall number of structural parts in an electrical vehicle and the volume taken up by the battery.  That’s the concept behind EMBATT (chassis embedded battery), which functions as structural energy storage.  It can cut the volume occupied by a battery in half, with serendipitous outcomes for lightness and structural efficiency.  This is similar to NASA-backed research on cubesat walls that also function as energy storage structures.

IAV, Krupp and Fraunhofer team up to produce EMBATT laminated battery

IAV is a German firm that provides consultation and partnerships with leading automotive companies.  It specializes in synergistic concepts and system-level thinking.  The company, working with Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden, and Thyssen Krupp System Engineering ,“Want[s] to use our experience from automotive development for renewable energies and decentralized energy supply.”  It sees strong links between these endeavors, and works to combine technologies that will enable greater efficiency.

Cylindrical cells, no matter how tightly packed, leave lots of space that does not store energy

Think of a Tesla battery pack, composed of individual cells connected in series and parallel to get the desired Voltage and Amperage necessary to make the wheels turn.  Because the large, underfloor pack uses cylindrical cells (originally 18650’s – 18 millimeters in diameter and 65 millimeters long), there is space around the contiguous cells.  EMBATT makes the battery layers that would normally be wound up “Tootsie Roll” style in a cylinder, flattens them out and makes them the actual floor of the vehicle.

IAV explains the consequences of that approach.  “Today’s lithium batteries… consist of a wound or stacked structure that is inserted into cylindrical or prismatic cell housings or sealed in a pouch. The energy density falls to 40 to 60 percent of the value at cell level merely by packaging cells individually and additionally installing the cells in the system. As a result, today’s battery systems only reach between 140 and 300 Wh/l (Watt-hours per liter).”

Comparison of EMBATT characteristics with other cells. The dark blue is Energy density per cell; light blue represents the share of active material per cell volume; Dark orange. Energy density per system; and light orange, Share of cell volumes per system

Fraunhofer explains that, “…Electric cars are equipped with hundreds to thousands of separate battery cells. Each one is surrounded by a housing, connected to the car via terminals and cables, and monitored by sensors. The housing and contacting take up more than 50 percent of the space. Therefore, the cells cannot be densely packed together as preferred. The complex design steals space. A further problem: Electrical resistances, which reduce the power, are generated at the connections of the small-scale cells.

EMBATT is a planar battery, and it essentially becomes the floor of the vehicle.  IAV battery system developer Michael Clauss says that such a setup of bipolar electrodes with a surface area of two square meters (21.5 square feet) “make it possible to to break up the conventional cell and module boundaries and integrate the energy storage system as a component into the vehicle chassis.”  Integrating the batteries into the vehicle’s underfloor “can double the share of active storage material up to 80 percent of battery volume.”

Up 850 Volts can be delivered currently (no pun intended), and up to 1,200 Volts in the future, enabling ranges up to 1,000 kilometers (620 miles).

The EMBATT bipolar battery consists of cells which are stacked in a stack-type manner such that the arrester of the negative electrode of a cell represents the contacting of the positive electrode of the next cell.  Thus, two electrochemical cells are connected in series – the one side of the bipolar electrode serves as an anode in one cell and the other as a cathode in the next cell.  The larger and thicker the electrodes are, the higher the capacity of the battery.

Production of the bipolar electrode on a pilot scale.

Most important in this battery, the bipolar electrode – a metallic tape that is coated on both sides with ceramic storage material – has two large, flat sides.  One side becomes the anode, the other the cathode.  Dr. Mareike Wolter, Project Manager at Fraunhofer IKTS, explains, “We use our expertise in ceramic technologies to design the electrodes in such a way that they need as little space as possible, save a lot of energy, are easy to manufacture and have a long life.  One of the core competencies of our institute is to adapt ceramic materials from the laboratory to a pilot scale and to reproduce them reliably.“  The partners hope to be able to demonstrate full-scale batteries in cars by 2020.

Certainly the ability to reduce battery size while retaining gravimetric energy density is a desirable goal.  Even more desirable is a smaller, lighter battery with greater energy storage capabilities.

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A Swan among the Ultralights

At this year’s Aero Friedrichshafen, Modern Wings showed off their Swan Ultralight, a nicely packaged machine that can fly on either fossil fuels or electricity.  Of course, we’ll feature the electric version here.

Dimensional drawing of Swan’s compact form

The Swan E115-22 is an electrically-powered airplane of 115 kilograms (253 pounds) empty weight powered by a 22-horsepower motor.  That empty weight puts it solidly into U. S. FAR Part 103 territory and SSDR (single-seat deregulated) requirements in Great Britain, and a 120 kilogram (264 pound) version complies with Regulation 120 in Germany.  Maximum takeoff weight is 300 kilograms (660 pounds), heavier than the 524 pounds Part 103 allows, and possible legal depending on how local FAA inspectors view batteries as part of empty or total weight.

Designers chose a high-wing, tractor-propeller configuration to help keep newcomers out of trouble, and crafted a nicely streamlined pod and boom with neatly faired landing gear.  This helps enclose the pilot, “…For smooth, pleasant flights without a heavy and expensive helmet and eases flights in low temperature weather conditions with no need of a sophisticated costume.”  Pilots sit on the center of gravity, allowing for a variety of sizes and shapes, with no adjustments required other than to seatbelt and shoulder harness to go aviating.  The airplane can accommodate those up to two meters (six feet, six inches) tall.  Cockpit comfort is given a high priority, with cooling ventilation for warm days and an optional heater available for cooler climes.  The video shows the Swan at the 2015 Aero, but disappointingly shows only the gasoline-fueled version.  Curiously, coverage of the Swan starts at 50 seconds.

Swan can manage four positive G’s and two negative, its lightweight carbon and aramid fibers and high-strength aluminum carefully chosen for each segment of the structure.  Flaperons are 25-percent of the wing chord and cover much of the trailing edge.  They move up a negative five degrees, enabling a cruise speed well above Part 103 maximums, but well within European limits.  Downward travel of 30 degrees slows landing speeds to well within Part 103 parameters.

Swan at 2017 Aero, featuring Eck-Geiger motor, E-Prop by Anne Lavrand’s French company

Power on the model displayed at Aero is an Eck/Geiger 16-kilowatt (22 horsepower) single-rotor unit which has a controller and battery packs well suited to the ultralight market.

When more such airplanes become available at prices more in line with people’s budgets for recreational flying (much like Chip Erwin’s Personal Sport Aircraft), we will see greater sales, especially if regulatory constraints are reasonable.  A craft such as the Swan would be an attractive vehicle for weekend adventurers, and group ownership might expand such opportunities to the larger community.

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Qinetix Motor at E-Flight Expo

QinetiX GmbH in Germany manufactures a motor and controller combined in one case to lower weight and simplify installation.  Their QPD-40, shown at the Aero Friedrichshafen E-Flight Expo and on their web page, seems to exemplify those goals.  Its 12 kilogram (26.4 pound) weight and 40 kilowatt (53.6 hp.) output gives it a power-to-weight ratio of 3.2 kilowatts per kilogram (2 horsepower per pound).

QuinetiX power system combines motor, controller in one case

Running on 60 Volts at a maximum 680 Amperes, the motor produces 212 Newton-meters (156.4 foot-pounds) of torque, swinging a propeller at only 1,800 rpm, allowing for quiet operation.  The liquid-cooled stator and power electronics will require some form of heat exchanger, but probably with fairly low cooling drag overall.

Only 90 millimeters (3.54 inches) thick and around a foot in diameter, the motor should fit neatly into streamlined propeller spinners.  Other uses in automobiles and wind turbines present hopeful potential applications for this neatly-packaged motor.

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SolarStratos Makes First Flight

SolarStratos, a feather-light 450 kilogram (990 pound), solar-powered airplane, lifted off for the first time on May 5 in Payerne, Switzerland.  Considering its 24.9 meter (81.69 feet) wingspan, the airplane shows designer Calin Gologan’s ability to squeeze performance from every gram of structure.  It flies nicely, too, with test pilot Damian Hischier enthusing, “The plane is very nice to [fly].  [Its] reactions are healthy, and we see that it was well designed.”

Liftoff and steady climb belies 32 kW (43 hp) motor

Sharing Payerne Airport with Solar Impulse, SolarStratos represents a different kind of adventure, ready to make five-hour flights to 75,000 feet (two hours up, five hours down).  Such flights can carry a pilot and scientific measuring equipment, or for those lucky enough to have the price of admission, a passenger.  Passengers on this high stratospheric journey will need to wear a pressure suit, and undoubtedly undergo hours of training on how to behave at such altitudes.

The Pulse reports, “Until now, reaching the stratosphere has required large quantities of energy or helium.  (Editor’s note: now it will only take a sunny day.)

“Reaching an altitude of 25,000 meters (82,000 feet) will pose huge technical and human challenges, SolarStratos points out on its website.

(Editor’s Note: Calin Gologan, the plane’s designer, supplied this longer video this morning, May 6.  It is in French, but most readers will get the idea.)

(He also sent this link, which includes this additional video.)

“The plane and pilot will also be subject to temperatures as low as -70 degrees Celsius (-94 degrees Fahrenheit), it said.

“And for weight reasons, the aircraft will not be pressurized, forcing [Raphael] Domjan to wear a spacesuit, meaning he will not be able to get out of the plane using a parachute in the case of an emergency, SolarStratos said.”

SolarStratos explains, “With this step completed, we can look forward to the next adventures with peace of mind. Of course, the road to flying at very high altitude is long, but we are confident of getting there. The intention is to get there step by step with confidence.”

Even in subdued sunlight, SolarStratos makes fine progress

Raphael and his co-pilot, Thierry Plojoux, will perform more flight tests, “so that we can demonstrate the aircraft’s flight capabilities at a major event in Quebec in June.”

The CEO of SolarStratos Roland Loos, appreciates the progress his team has made. “We are particularly pleased to have reached this crucial stage in the development of our project.”

Raphael Domjan has excellent solar eco-adventure credentials, having helmed PlanetSolar, the largest solar-powered boat in the world, around the world.  His enthusiasm for saving the planet matches that of his Payerne neighbors, Bertrand Piccard and Andre’ Borschberg, pilots of the Solar Impulse.  The sun shines brightly on that corner of Switzerland, indeed.

(Addition; May 8, 2017.)  Calin wants us to know that The manufacturer of The aircraft is Elektra Solar GmbH ( Elektra-solar.com) a Merger of PC-Aero and Elektra-UAS , and at same time A spin-off from DLR ( German Aerospace), Institute of Robotics and Mechatronics.

He adds, “We work very close together with The DLR for Autonomous flight, payloads and flight simulation.  There is also a bilateral frame Agreement between our company , DLR and SolarXploreres SA.”  Calin’s a busy man: “I’m at the same time The CEO of Elektra-Solar and a Shareholder of SolarXplorers SA in Switzerland.”

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Lilium Flies Short Demonstration

A German vertical takeoff and landing (VTOL) machine made a surprise test flight recently, seemingly too early in its development to be airborne.  Lilium, its name derived from that of Otto Lilienthal, flew its full-sized, two-seat prototype in April, at a partially-disclosed location – somewhere close to Munich.  Awash in technology, the craft looks well adapted to its role as an urban cruiser, lifting its passengers above the earthbound fray and flying them at the speed of a Formula One racer to their destination.

Its 36 motors drive ducted fans grouped in threes.  24 motors fan out along the wings and 12 cluster along the nose.  Lilium calls their power plants electric jet engines and groups three engines in one “flap” – essentially a rotatable block of three.  Designers distribute four flaps along the canard nose and eight along the trailing edge of the wing.  Rotating the blocks down produces upward thrust and vertical flight.  Rotating them forward produces forward thrust and high speed (up to 300 kilometers per hour or 186 mph) forward flight.

Lilium flaps, essentially blocks of three motors, act as vertical lift devices and forward thrusters

Lilium claims this approach simplifies the normally complex mechanisms for achieving VTOL flight, requiring only tilting the flaps to go up, down, or forward.  Differential thrust in horizontal flight controls direction and does away with a vertical tail.

Obviously, all this requires a powerhouse software suite, actuators, and motor controllers.  Nobody we know has flown this many power plants without software assistance.  Even a B-36 had only six reciprocating engines and four jets (six turning and four burning), and required highly-skilled pilots.  If Lilium were manually controlled, it would be particularly dicey in transitions from hovering to high-speed flight, for instance.

Even three motors out still allow control of the aircraft

Lilium reduces the white-knuckle experience, though.  “As the engines always maintain attached flow on the surface of the flaps, the Lilium-Jet is highly maneuverable in any flight condition. It can do climbing, curves and high-rate sinking in any phase of a transitional flight. This feature is highly important when flying in narrow corridors in urban areas or for avoiding unexpected objects during a transition flight.”

“Ultra redundancy” allows control even with multiple failures, and since the machine is a consumer product, designers have built in safety systems to allow safe landings regardless.  Further, “…the system has a built-in flight envelope protection: meaning that even if the pilot requests a dangerous maneuver, the computer does not exceed safety limits of speed, roll, and pitch.”

Lilium electric jet engines are small, with unspecified rotational speed or output

Even with 36 spinning turbines, these are so small and contained that they produce little vibration, according to Lilium.  The machine is also reportedly low in noise, although the test flight video overlays a music sound track to cover any untoward frequencies.  They are shielded in such a way as to prevent a ‘cascade effect” if one motor tosses turbine blades, for instance.

The “several thousand Lithium-Ion cells” in the battery pack are “built with many independent parallel strings of cells ensuring multi-redundancy also on the energy supply.”  The battery pack is also designed to “contain” a thermal runaway of even several cells and still maintain flyable power.

As a final measure, every Lilium has a full-aircraft parachute.  A “water resistant” carbon fiber structure provides security if the descent happens over a lake or ocean.

The biggest hurdle might be range, claimed to be 300 kilometers, or one hour of flight.  Perhaps that’s why initial flights are shown within fairly tight boundaries, competing with ground-bound taxis, but at much lower prices.  Doubtless, the flight vehicle will cost more than a Prius or Hyundai hybrid, so will low costs for electric charging make up for the initial price differential?

Map compares times, costs for Lilium vs. ground transportation

The test flight as shown is short and involves no passengers.  The rapid development schedule slows a bit for that event, with first people-carrying trips not until 2019.  In the meantime, this complex craft will probably be well sorted out and refined.  Several million dollars and DLR (the German space agency) assistance have helped bring this about.  Will it be part of Uber’s network, or a worthy competitor when it comes to market?

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A scad of news about electric aircraft hit the internet and newsstands last week.  Even USA Today reported on the Uber Elevate Summit in Dallas, Texas.

First flight of Aurora’s eVTOL aircraft on April 20, 2017. Photo:
PRNewsfoto/Aurora Flight Sciences

Big news came from Uber’s announcement that it intends to offer electric VTOL (vertical takeoff and landing) air taxi service in Dallas and Dubai by 2020.  Bigger news for SAS participants is that it is partnering with Pipistrel and Aurora Flight Sciences.  Jeff Holden, Uber’s chief product officer, said Bell Helicopters, Brazil’s Embraer, and Mooney Aircraft will also provide “concepts and technologies” for the near-term launch.

According to Aviation Daily, “Aurora has already flown a quarter-scale model of its concept, using elements of the electric propulsion system flown in the subscale demonstrator for DARPA’s XV-24A LightningStrike high-speed VTOL aircraft.”

Aurora’s concept for Uber is a two-seat eight-rotor (for vertical lift) and tail propeller (for forward propulsion) aircraft weighing around 1,500 pounds.  Derived from the company’s XV-24A X-plane, Aurora’s Uber vehicle will use components from existing craft – the autonomous flight guidance system from its Centaur optionally-piloted aircraft, the collision avoidance system from the AACUS program, and the battery-electric propulsion system from the XV-24A demonstrator.  John Langford explains, “The Uber Elevate mission is all about low noise, high reliability, and low cost.  By drawing on our nearly 30 years of successful autonomy and robotic programs, Aurora is well positioned to deliver on this urban solution. We have already built and flown the first proof-of-concept aircraft and we’re excited to partner with Uber in accelerating the eVTOL initiative.”

Bell Helicopters left this editor wondering what will come from this experienced purveyor of vertical lift machines.  They allude to a hybrid-electric VTOL, but only shared repeated dream-like images suggesting what may be.

Embraer CEO Paulo Cesar de Souza e Silva says the company is interested in designing, operating and maintaining e-VTOL aircraft, and also in air traffic control. The initial project will be conducted by Embraer’s new Business Innovation Center in Melbourne, Florida.

Pipistrel, already a leading manufacturer of electric fixed-wing light aircraft, will develop e-VTOL vehicles to be used in a flight demonstration in 2020, said CEO Ivo Biscarol.  His presentation to the Summit is shown in full below.

Mooney has experience with rapid prototyping of composite light aircraft and has teamed with CarterCopter to develop a larger platform with four to six seats based on the hybrid aircraft/helicopter configuration developed by Jay Carter’s company.

The Carter Copter/Mooney collaboration will have much of the Carter Copter’s configuration, hold up to six passengers

According to the Aircraft Owners and Pilots Association (AOPA), downtown Dallas will host the first four “vertiports,” now being designed by property developer Hillwood, led by Ross Perot, Jr.  One vertiport will be near the Dallas Cowboys team headquarters, 21 miles from Dallas/Fort Worth International Airport.  A 21-mile flight between the two will take six minutes (vs. one hour, 10 minutes for a ground-bound Uber car) and cost about $1.32 a mile, according to Uber’s Jeff Holden.

Aviation Week further reports, “Perot said vertiports are then planned at the American Airlines Center arena in Dallas, the existing heliport at the Kay Bailey Hutchison Convention Center in downtown Dallas, and another in downtown Fort Worth. Hillwood also owns Fort Worth Alliance Airport, which Perot said could be a manufacturing and training center to support UberAIR.”

In Dubai, Uber is working with Dubai’s Roads and Transport Authority to jointly study pricing models, VTOL routes, network optimization and identify vertiport locations.  They hope to launch demonstration flights in time for the World Expo there in 2020.  Hillwood also operates in Dubai.

Chargepoint, reputedly the largest electric-vehicle charging network in the world, will develop a special charger that will enable rapid turnaround of the e-VTOL aircraft.  It will be interesting to see if their design will allow compatibility with other electric aircraft on the horizon.  Plug variety continues to be an issue for electric car owners.

UberAIR operations will begin with piloted aircraft, but move over time to optionally piloted and eventually fully autonomous flights.  Holden says Uber’s initial goal is for flying in its e-VTOL aircraft to be twice as safe as driving a car.  Initally, all flights must have a pilot on board, perhaps creating a flight school bonanza.  This may be a problem for Uber, according to Bryant Walker Smith, a “transportation tech scholar” with Stanford Law School.  He thinks regulations and added costs may leave Uber in an economic quandary.  “It’s FAA’s way, or no way,” he’s quoted by the (San Jose) Mercury News.  Smith accepts the technology, but wonders if Uber has taken pilot pay and maintenance costs into consideration.

Regardless of cautions and cavils, with former NASA innovation leader Mark Moore heading up Uber’s efforts, it will be an exciting three years as commercial introduction of sky taxis (much better phrase than “flying cars,” don’t you think?) nears reality.

 

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