Acentiss is a German engineering and consulting firm specializing in medicine, aerodynamics, and recently, the creation of two small electric motors for light aircraft. Located almost symbolically between Robert Koch Strasse (Nobel Prize in Medicine) Max Plank Strasse (Nobel in Physics), and EinsteinStrasse (Nobel in Physics) in Ottobrunn, the company not only provides design services for wind turbines and their components, assistance with process flows for the manufacture of medical equipment and devices, and consultancy services for the automotive and aeronautical industries, but has created components for use on light aircraft and unpiloted aerial systems.
Acentiss dual-rotor unit as shown at 2016 Aero Expo at Friedrichshafen
Their motors, developed with assistance from Geiger Engineering, look a great deal like the HP-25D from that company, often seen flying on PC-Aero aircraft. The two motors, both 218 millimeter (8.6 inches) in diameter, produce a maximum of 32 kilowatts (42.8 horsepower) or 40 kW (53.6 hp). The smaller motor can produce 25 kW (33.5 hp.) continuously at a leisurely 1,950 rpm, and the larger (thicker) motor can generate 32 kW at 2,200 rpm. Both motors run at 58 Volts, meaning a high amperage helps create the torque to turn a propeller at low rpms. Many think low voltages will provide greater safety for operators.
The less powerful motor weighs 8.9 kilograms (19.6 pounds) and the more powerful 11 kilos (24.2 pounds). This light weight, coupled with the weight of the recommended dual motor controllers from Geiger Engineering that weigh only one kilo (2.2 pounds) each
Tandem rotors on both power plants can run independently, the same as those on the Geiger HP-25D, enabling economical flight on one rotor, or a “get-home” mode at half power that will at least stretch the glide in the event of one rotor or controller failing.
Elias, Acentiss’ modified Elektra One, showing electric retractable landing gear
Acentiss is flying the motor on a modified PC-Aero Elektra One, but one which mounts Acentiss’ retractable tricycle landing gear. For surveillance operations, The Acentiss Elias pulls the gear inside the fuselage for the nose wheel, and inside the wings for the main wheels, making an unobstructed view for belly-mounted cameras and sensors. The gear weighs only 22 kilograms (48.4 pounds), a creditable weight for something that allows higher performance for an already clean airframe. Solar cells can extend the airplane’s range and endurance.
11-meter span is readily apparent in this view
The 11-meter (36-foot) span, 320 kilogram (704 pound) craft can carry batteries sufficient for 1.5 hours’ endurance, and significant test gear that can be monitored by an Acentiss Ground Control Station (GCS). Depending on whether a pilot is on board, the system can monitor and control, by visual or data transmissions, the mission based on pre-set plans or manual over-rides. It can check the multi-spectral, high-definition sensors on board Elias and record their output.
Beyond the interesting pair of new motors, Acentiss, with its many fingers in many technological pies, may pull out a surprising number of plums in the near future.
Solar Ship, located in Toronto, Canada, builds solar-powered triangular, blimp-like flying machines that could serve as lifelines to the world’s most remote places. Solar Ships range from an 11-meter wide (it’s hard to call it a wingspan) envelope to a projected 100-meter (328 feet) wide monster that could carry up to 30,000 kilograms (66,000 pounds) for a minimum of 2,000 kilometers (1,240 miles).
The blog reported on Solar Ships three years ago, when their few flying examples were testbeds for the possible future development of practical load haulers. Combining buoyancy with aerodynamic lift allows large payloads and great short-field performance, making their craft viable “bush” planes. That the company can now build larger craft will demonstrate their concept to a wider audience.
With operations based in Ontario, Canada; Cape Town South Africa; Lusaka, Zambia; Kampala, Uganda; and Shenzen, China, Solar Ships is located near many already isolated spots which have the potential to become even more cut off. The craft’s “lifting capacity of a truck and the performance of a bush plane” make it well suited to rescue and supply efforts by the humanitarian organizations that will use these unique machines.
Manaf: Serving up to 400 Million People
Manaf explains its mission this way: “Located in Nairobi, Bukavu and Bujumbura, Manaf uses bush planes to service the interior of Africa, an area with a population of 400 million people and rapid growth. Flying into remote areas in the DRC, South Sudan, Uganda, Rwanda, Burundi, and Tanzania, Manaf works with local entrepreneurs, UN agencies and NGOs to bring food and medical supplies to people who do not have regular access to cargo services.”
Solar Ship prototypes in hangar, showing innovative approaches to basic configuration
This week’s purchase of two Caracal and two Wolverine aircraft will give the Solarship/Manaf venture extremely short takeoff and landing (XSTOL) capabilities, allowing them to use areas as small as soccer fields. These will “be used for cargo delivery and disaster relief in remote areas in East and Central Africa,” according to Manaf. The joint venture, Peace and Freedom Services, will be able to haul small loads with the Caracals, while the two Wolverines can carry a 20-foot shipping container with a minimum payload of five tons.
Manaf CEO Fred Nimubona sees an existing need based on the harsh conditions in the regions served in conflict zones. “The need for Peace & Freedom Services is immediate in our region. Many lives are being lost and our joint venture promises to improve the quality of life in regions that have, up until now, been inaccessible or diminished by war.”
Prototype Solar Ship in flight, showing inflatable wing which adds buoyancy to aerodynamic lift
Being able to drop that amount of cargo into a constrained space expands the scope of what relief services can accomplish. Combining the airships with the two DC-3s purchased by Manaf gives a full range of capabilities and the ability to retrieve cargo from a reasonable distance for the older cargo aircraft, deliver it to a central airport, then disperse it to otherwise unserved points in East and Central Africa. Bringing “critical cargo: food, clothing, medical supplies, and basic necessities” to hard-hit regions could aid thousands who might otherwise suffer privation and even death.
With solar-powered missions of mercy already part of Solar Ship’s future, perhaps a broader use might come from commercial hauling, with the potential to lower freight costs and speed deliveries, even at their leisurely cruise speeds. As part of their outlook on “innovative disruption,” the company sees applications in service to environmental and scientific work. Those willing to look beyond the ungainly appearance of these fat delta-winged hybrids might be well rewarded for their choice of an unusual approach.
Solar Gamera, an extension of the human-powered helicopter that achieved the longest HPH duration flight in 2013, just made the first solar-powered helicopter flight. In 2014, a group of undergraduate students at the University of Maryland turned Team Gamera into Solar Gamera, “to test the feasibility of applying solar power in achieving human helicopter flight.”
Ph.D. student William Staruk, a member of the original HPH team, reflected, “Today you are seeing the first successful flights of the Gamera Solar-Powered Helicopter. You are seeing aviation history being made in the history of green aviation and rotary blade aviation.”
Gamera’s lattice-work framework, 100-foot square with extremely large rotors at the ends of four beams, carried materials science major Michelle Mahon on two short flights. The best effort lasted nine seconds and gained an altitude over a foot.
Staruk explained, “It’s just a matter of drift before [Solar Gamera] gets longer flights. It’s easier to trim than human-powered helicopter thanks to electronic controls.”
Note the mechanical complexities in the original human-powered version, including the “lost-string” technique pioneered by Paul MacCready. The electric version is less mechanically extreme, with software taking over some of the functions originally managed by a Rube Goldberg arrangement.
The flight had students and advisers extolling the virtues of the project. Distinguished Professor and Gamera faculty advisor Inderjit Chopra beamed. “This is about inspiring and educating students, that’s our product here. No one thought that solar energy could lift a person [via helicopter].”
Gamera 2015-2016 team lead Anthony Prete (B.S. ’16) said, “When I started this, I had no idea what I wanted to do with my engineering degree. This experience focused me into something, design.”
The project has been active form more than six years and involved more than a hundred students from across the Clark School in a project most would never have envisioned in their high-school years.
“’This project has come a long way in the past six or seven years from human-power to solar-power,’ added Staruk. ‘So we are breaking barriers of all sorts in aviation with this one airframe and we are very proud of that work here at the University of Maryland.’”
Competition from Toronto
In 2013 AeroVelo’s “Atlas” won the prestigious $250,000 Igor I. Sikorsky Prize from the American Helicopter Society by reaching an altitude of 3.3 meters (10.8 feet) under the pilot’s (Reichert’s) own power, and hovering for 64 seconds. Although Gamera missed the gold, it achieved several subsequent records as noted above.
A Proud Cinematic Heritage
Cinematic superstar Gamera may soon re-appear on the big screen
Gamera is named after a movie-star turtle, a large, pugnacious, flying, fire-spouting testudine created by Daiei Studios to compete with Toho Studio’s ever-popularGodzilla. Gamera turned out to be less destructive than the competition and even protected children in his films. A note of hope for Japanese rubber monster fans: a new version of Gamera is scheduled for release soon.
Dipl-Ing* Ingmar Geiß, Deputy Project Manager for e-Genius with the Institute of aeronautical engineering at Stuttgart University shared the news that e-Genius flew with its range extender for the first time on September 15. He notes that while the battery-powered airplane can manage trips up to 300 kilometers (186 miles), the hybrid engine/generator pod will enable flights up to 1,000 kilometers (620 miles). This would equal a trip from Stuttgart to Barcelona, Spain, according to the e-Genius web site.
e-Genius with engine/generator pod on right wing. Pod is easily attached and detached to allow flight as pure battery-powered craft
As the school explains, “With [the] e-Genius hybrid most flights of a typical user case can be done in the cost and energy efficient battery mode – for all longer flights the range extender can be used.
Generator system control requires no pilot input, everything being done automatically. If the pilot wants to set down at the end of a trip with a certain amount of battery energy on board, e-Genius has an ingenious “look-ahead” feature to modulate the battery to achieve the desired level at the end of the flight.
Quiet and Efficient
Already recognized as one of the quietest aircraft on record (56-62 dBa in the 2011 Green Flight Challenge), the hybrid craft takes off on battery power alone and switches the engine generator on when the airplane achieves cruise altitude. This type of strategy makes e-Genius a good neighbor. As Ingmar reports, “The system left an excellent impression – additional noise in the cockpit was barely hearable. So we could still enjoy our silent electric aircraft and didn’t have to use headsets.”
e-Genius climbing out on pure battery power. Internal combustion engine is turned on at altitude to avoid disturbing people below (not that they would notice any additional noise)
The blog described the hybrid engine/generator pod last year, a compact Wankel engine powering an equally compact generator while consuming only five liters per hour of fuel. Cruising at over 100 mph, the airplane would use only one liter per 20 miles at about 75-percent power (for the engine/generator), or 1.3 gallons per hour. Fuel consumption would doubtless go down at lower generator outputs.
Because Wankel engines tend to be thirsty, estimable reader Howard Handelman sent an excellent critique of last year’s entry, including compromises in battery-pack size, different approaches to controlling fuel usage and getting the most out of a hybrid-package.
e-Genius hybrid schematic. Pilot does not notice changes in operation, software combining outputs from alternator and batteries automatically to run motor
A Ground-based Equivalent
Another German product, the BMW i3, has a range extender that allows one to run beyond low battery range. One owner apparently does a lot of local driving and uses only battery power for most of his commuting. “However, I have to admit, I thought I’d need to use the range extender more than I actually have. Of my 56,000+ miles, only 1,925 miles have been with the range extender running. I’ve bought 50 gallons of gas (I kept records) and averaged 38 miles per gallon while the range extender was running, just slightly less than the EPA rating of 39 mpg.
Tom Moloughney’s 1,000 mpg BMW 13 Rex. It used less fuel than he drinks in coffee per month, and less tan his gardner’s tractor burns mowing his two-acre lawn each year. Charging at home comes from the solar roof on his house
“But just how little gas is that? Well, as I’ve said, I’ve owned the car for 27 months now, so that averages out to me needing to refill the tiny 1.9 gallon gas tank about once every month — I drink more coffee than that in a month! However, refueling hasn’t been nearly that regular. I’ve gone stretches of four or five months at a time without needing to buy gas. But I’ve also taken the car on a couple of road trips of two or three hundred miles where I needed to refuel three or four times in the same day to complete the journey. In fact, the majority of my REx miles were accumulated on long trips. These trips simply wouldn’t have been possible in an i3 BEV, as charging infrastructure is only now becoming available along the routes I’ve traveled.”
Such strategies will be the source of endless speculation and controversy until batteries become energy-dense enough to allow what drivers consider “normal” trips without recharging. Aircraft designers and builders will then have access to power sources that will allow long flights and great performance – something fairly elusive thus far except for rare aircraft such as e-Genius.
The e-Genius fuel tank holds 100 liters, so at 5 liters an hour, 16-hour flights (with reserve) would be possible – too much for any rational need other than record breaking.
*Dipl-Ing (Diplom-Ingenieur (German equivalent of M.S. degree, according to Free Dictionary.com
Airbus and its partner Local Motors have just finished a successful design challenge for delivery drones that can carry things like emergency medical supplies to selected destinations. Recent announcements and the release of a patent drawing show Airbus is doing serious work toward delivering humans to their selected destinations in a scaled-up version of such drones. Many brilliant people have tried to combine the benefits of ground and air transport over the years, including Molt Taylor, designer of the rightly famous Aerocars. The example at Seattle’s Museum of Flight causes docents to lower their voices out of respect for the accomplishment.
Airbus’s quadrotor-like commuter, a hybrid platform for avoiding traffic jams
Recently, Airbus formed a group in California’s Silicon Valley called A3, or A Cubed. The group earned a patent on a large quadrotor, passenger-carrying machine which could well be an aerial Uber-type vehicle. That certainly fits its Airbus parentage. A3’s web site contains this mission statement:
Unicorns and Jackalopes
“We are the Silicon Valley outpost of Airbus Group, the parent of Airbus (the leading maker of large commercial aircraft), Airbus Helicopters (the world’s largest supplier of civil helicopters), and Airbus Defense & Space (which makes satellites, drones, and military aircraft, and provides cyber defense capabilities). The mission of Airbus Group is to make things that fly. Our aim is to define the future of flight.
“We believe that the future is created through episodic disruption with intervening periods of incremental innovation. Our mission is to build the future of flight now, by disrupting Airbus Group and its competitors before someone else does.
“We solve big problems by employing world-class experts and by developing fertile partnerships. Our projects are built on rigorous analysis, novel insights, and commitment to unreasonable goals. We fly in the face of risk and deliver with maximum speed. We are A³ by Airbus Group.”
A combination of jackrabbits and antelope, jackalopes are often seen on tavern walls in the American West
Willing to take big risks to achieve unreasonable goals, it follows that a typical executive in the group would be a different breed, because he or she would lead a unicorn organization – a Silicon Valley startup worth over a billion dollars (at least at the parent company level). Airbus describes a project manager like Jane Jackalope, a mythical creature leading a rare company. “You are a jackalope of all trades. You are that rare creature at the intersection of a dreamer, a project manager, a chief engineer, and an evangelist. You are the world’s leading expert in your domain. You have an idea that will disrupt it. And you are passionate about bringing this idea to life.”
One would expect a big leap in technology from a company that sponsors the Perlan Project, with their patented design for their commuter – a multipropeller City Airbus vehicle – looking a great deal like the future in the film The Fifth Element (in which Bruce Willis played an aerial cab driver, but the cab was more Checker-like than aerodynamic). There won’t be a driver on these sky taxis, though, everything guided by programming similar to that being devised for a pilot test program in Singapore.
Drone delivery system planned by National University of Singapore (NUS) may prove a model for Airbus’s human transport
A Competitive Link
With 425 entries from their recent Cargo Drone Challenge, Airbus has a great deal of corroborating evidence that they are headed in the right direction, like minds tending to take similar paths. Given the mission, an electric, human-carrying pod will look a great deal like the smaller drones – with a hybrid drive system to provide the necessary full-weight lift and usable range in horizontal flight.
The patent specifies an “Aircraft Capable of Vertical Takeoff” with wings to allow horizontal flight. There are four rotors on the drawing, and a tail-mounted propeller to provide forward flight. As the video shows, rotors would hide inside outer pylons when the propeller and wings take over to provide high-speed transit.
An internal-combustion engine driven generator would keep things charged, with the engine also powering the forward-facing propeller.
A twin-engine version would have two forward-facing propellers to increase speed or allow a larger payload. Because electric power allows motors to be scaled to required sizes, the airplane could be scaled down to drone size or up to large cargo aircraft size. The patent seems to indicate at least a two-passenger configuration, probably a good starting point to allow inexpensive operation, but limiting in getting the family from the airport to the destination amusement park.
The Airbus A3 group seems to be willing to leap tall buildings with their imaginings, and their products may soon compete with e-volo and eHang 184 in scooting passengers efficiently over the gridlock below.
Richard Glassock, a long-time contributor to the blog and now a Research Fellow in Hybrid Propulsion Systems for Aircraft at the Institute for Aerospace Technology, the University of Nottingham, England, shared this news about an Airbus-sponsored contest for cargo drone designs.
Zelator, first place winner of the Airbus/Local Motors Cargo Drone Challenge. It also took third place in the Cargo Category
Local Motors, well known for its 3D-printed automobiles, and Airbus Group, well known for its range of commercial and military aircraft, just completed a design contest that drew 425 entries. Rewards were significant for the top three places in the competition, with a main award First Place prize of $50,000, a trip to the Farnborough Airshow in England, and a “1-of-a-kind Cargo Drone Flight Jacket with personalized patch.” Second place earned the winner $20,000 and third place $10,000, with garnering each a trip to the Farnborough Airshow. Airbus executives judged the entries and decided winners.
Design criteria included required capabilities and characteristics:
Vertical takeoff and landing (VTOL) and efficient forward flight.
Hybrid design between multi-rotor and fixed-wing aircraft.
Two flight modes: hover and flight.
Modular payload system.
Weighs less than 25 kilograms.
Single, fixed cargo bay suitable for payloads of three to five kilograms (6.6 – 11 pounds).
Easily accessible and interchangeable cargo bay which is impossible to jettison in flight
Cruise speed of at least 80 kilometers per hour (49.6 mph), and a maximum speed of 194 km/h (120.3 mph).
Secondary prizes for cargo and “community” (as judged by the Local Motors community) had fewer prize dollars, with first, second and third prizes in each category. Nine prizes were available and five competitors took them all. Harvest Zhang from Mountain Valley, California, harvest three: second place in the Main Prize, second in the Cargo Prize, and third in the Community Prize.
1st: Alexey Medvedev from Omsk, Russia for ZELATOR
2nd: Harvest Zhang from Mountain View, California (United States) for Volans
3rd: Dominik Felix Finger from Aachen, Germany for Minerva
1st: Finn Yonkers from North Kingstown, Rhode Island for SkyPac
2nd: Harvest Zhang from Mountain View, California (United States) for Volans
3rd: Alexey Medvedev for ZELATOR
1st: Frédéric Le Sciellour from Pont De L’Arn, France for Thunderbird
2nd: Finn Yonkers from North Kingstown, Rhode Island for SkyPac
3rd: Harvest Zhang from Mountain View, California (United States) for Volans
Volans, which took second place in the Main Prize, second in the Cargo Prize, and third in the Community Prize categories
Jay Rogers, Local Motors CEO and co-founder, sees the promise in the contest results. “Phase I of our partnership demonstrated to Airbus the power of community-based creation and open innovation, Phase II of our work together will now demonstrate Airbus’ commitment to the community. The results will be nothing short of game changing and I could not be happier to continue our journey into the world of UAV, built on an open system, with Airbus.”
Jana Rosenmann, Head of UAS (Unmanned Aerial Systems) with Airbus Group, shares Jay’s enthusiasm. “We are excited to expand our experience with co-creation and the community to the realm of software and services. We are optimistic that Phase II of the project will lead to challenging prevailing technologies and business models in the world of drone services.”
The two companies have created a digital distribution platform for drone-based apps and services, including a store that sells drone-based services designed and developed by an open-source community, part of the Local Motors corporate philosophy, apparently. Services will be delivered by Airbus Drones.
Mark Zuckerberg, founder and head of Facebook, met with Pope Francis yesterday. The Pope, a known follower of high-technology innovations, has declared the Internet a “gift from God,” and emphasized the importance of building a connected society that is “healthy and open to sharing.”
As Digital Trends.com reports, Zuckerberg is the latest representative from Silicon Valley to be granted a Papal audience. He follows Apple CEO Tim Cook, Alphabet chairman Eric Schmidt, and Instagram CEO Kevin Systrom, but unlike them, brought a gift, a scale model of Facebook’s Aquila solar-powered drone soon to be carrying the Net to remote areas of the world.
The smiles on their faces indicate a happy meeting between the Pontiff and the programmer
Digital Trends reports that Zuckerberg took to Facebook (of course) to report on the meeting, explaining there are “parallels between the Pope’s mission of ‘communicating’ with people around the world and his company’s goal of providing internet access to underserved regions.”
Zuckerberg told his Facebook followers, “Priscilla and I had the honor of meeting Pope Francis at the Vatican. We told him how much we admire his message of mercy and tenderness. It was a meeting we’ll never forget. You can feel his warmth and kindness, and how deeply he cares about helping people.”
Priscilla Chan, Mark’s wife, had Facebook thoughts to share. “Mark and I had the honor of meeting Pope Francis and discussing our shared mission of reaching and serving all of those in need.
1 Billion and counting, Facebook hopes to extend Internet coverage to place that don’t yet have electricity
“It was also a special experience to connect with him in his native language of Spanish.
“I feel inspired and blessed to continue making our impact at the Chan Zuckerberg Initiative.” The inititative is a long-term educational effort to spread learning worldwide. As Priscilla and Mark declare on the Initiative’s web site, “The only way that we reach our full human potential is if we’re able to unlock the gifts of every person around the world.”
It’s not unreasonable to think that Facebook’s drones could play a large part in that mission, technology in this case enabling the fulfillment of a spiritual goal.
Boron nitrite nanosheets (blue and white atoms) act as insulators to protect a barium nitrate central layer (green and purple atoms) for high temperature energy storage in sandwich battery. Apparently, the sandwich layer can be rolled into a cylindrical cell. Illustration: Pennsylvania State University
Penn State University materials scientists have achieved the goal of making a “polymer dielectric material with high energy density, high power density and excellent charge-discharge efficiency for electric and hybrid vehicle use.” Their battery resembles the sandwich construction of modern aircraft shells ranging from ultralight sailplanes to 787 Dreamliners. The “sandwich-like structure that protects the dense electric field in the polymer/ceramic composite from dielectric breakdown,” according to researchers.
Rather than relying on the often-used BOPP – Biaxially Oriented Polypropylene Films – the Penn State team turned to a sandwich structure nanocomposite, termed SSN-x, in which the x refers to the percentage of barium titanate nanocomposites in the central layer.
Outstanding Electrical Properties of SNN-x
SNN-x, according to the researchers, has several times the energy density of BOPP and essentially the same discharge energy at 70° C (158° Fahrenheit), BOPP’s upper operating limit. SSN-x can thrive in 150° C (302° F) environments. This allows “the elimination of bulky and expensive cooling equipment required for BOPP.”
Energy and Power density benefits make for a more compact battery package, while the potential to incorporate the SNN-x battery into an EV structure might springboard real design advances.
Team leader Qing Wang, a professor of materials science and engineering at Penn State, sums up the significant differences . “Polymers are ideal for energy storage for transportation due to their light weight, scalability and high dielectric strength. However, the existing commercial polymer used in hybrid and electric vehicles, called BOPP, cannot stand up to the high operating temperatures without considerable additional cooling equipment.”
Materials make up one part of the Penn State achievement, but the physical structure of the battery adds considerably to its long-term performance.
Strong electric fields tend to leak energy in the form of heat, which interferes with battery stability and charge-discharge efficiency. Researchers tried to overcome this dichotomy in two-dimensional form by using different materials to balance competing properties. They still faced the breakdown of the battery structure as temperatures elevated.
The sandwich’s top and bottom layers block charge injection from the electrodes, allowing the central layer to contain all the high diaelectric constant ceramic/polymer filler – barium titanate – that enables high energy and power density – usually two competing desirables. The outer boron nitride nanosheets in a polymer matrix are excellent insulators.
Wang claims, “We show that we can operate this material at high temperature for 24 hours straight over more than 30,000 cycles and it shows no degradation.”
Self-repairing Structural Characteristics
Not noted in the Penn State writeup, a characteristic of the boron nitrite sandwich facings might have immense importance in creating actual structures with this material.
Looking forward to possible commercialization of the process, the team is performing studies on larger scale, reasonable cost approaches to making the materials. Wang says, “We have demonstrated the materials performance in the lab. We are developing a number of state-of-the-art materials working with our theory colleague Long-Qing Chen in our department. Because we are dealing with a three-dimensional space, it is not just selecting the materials, but how we organize the multiple nanosized materials in specific locations. Theory helps us design materials in a rational fashion.”
“The demand for a new generation of high-temperature dielectric materials toward capacitive energy storage has been driven by the rise of high-power applications such as electric vehicles, aircraft, and pulsed power systems where the power electronics are exposed to elevated temperatures. Polymer dielectrics are characterized by being lightweight, and their scalability, mechanical flexibility, high dielectric strength, and great reliability, but they are limited to relatively low operating temperatures. The existing polymer nanocomposite-based dielectrics with a limited energy density at high temperatures also present a major barrier to achieving significant reductions in size and weight of energy devices. Here we report the sandwich structures as an efficient route to high-temperature dielectric polymer nanocomposites that simultaneously possess high dielectric constant and low dielectric loss. In contrast to the conventional single-layer configuration, the rationally designed sandwich-structured polymer nanocomposites are capable of integrating the complementary properties of spatially organized multicomponents in a synergistic fashion to raise dielectric constant, and subsequently greatly improve discharged energy densities while retaining low loss and high charge–discharge efficiency at elevated temperatures. At 150 °C and 200 MV m−1, an operating condition toward electric vehicle applications, the sandwich-structured polymer nanocomposites outperform the state-of-the-art polymer-based dielectrics in terms of energy density, power density, charge–discharge efficiency, and cyclability. The excellent dielectric and capacitive properties of the polymer nanocomposites may pave a way for widespread applications in modern electronics and power modules where harsh operating conditions are present.”
Fixed wing drones have advantages – even though rotary-wing craft are in the spotlight these days. Your editor recently saw two quadrotors in a few days: one at a state park, its operators capturing the weekend crowd ogling a spectacular waterfall; and the second at a wedding, photographically memorializing a happy event.
Given the increasing capabilities of civilian drones like those, one wonders where the military and government agencies, without the budget constraints of the average private citizen, can take this trend. John Brown, President and CEO of Silent Falcon, was on hand at the 10th annual Electric Aircraft Symposium held in the San Francisco Airport Marriott Waterfront hotel. His talk explained the array of hardware, software and unique uses for the 14.4-foot wingspan flyer.
Originally conceived by George Bye as part of Bye Aerospace, the airplane spun off into Silent Falcon UAS Technologies, and is now rebranded with a new logo and web site.
Small and quiet enough to avoid detection even when passing overhead, yet large enough to carry a three kilogram (6.6 pound) payload that can fit into its 230-mm-(9 inches) long, 140-mm-(5.5 inches) wide and 200-mm-(8 inches) deep cargo bay, the Silent Falcon can perform a variety of Intelligence, Surveillance and Reconnaissance (ISR) missions.
Payloads can include four different electro-optical/infrared (EO/IR) sensors, which can offer enhanced visualization in the visible and invisible light spectra; a gas imaging Midwave Infrared (MWIR) camera. a hyperspectral camera, spectrometer, and three different mapping payloads.
Multispectral imaging can reveal hidden aspects of an otherwise common scene. The video from NEON, the National Ecological Observatory Network, shows the civilian applications of the different types of sensors which Silent Falcon can carry, but at a far lower cost than that of a twin-engine turboprop.
It will have greater range than a multi-fan VTOL machine, because the long wing allows low power settings in cruise, while a quadrotor, for instance, has to lift its total weight continually.
The Silent Falcon might actually have greater endurance than the twin, with solar panels on the wings extending flight times and allowing greater persistence for military and law-enforcement missions. Most fixed-wing UAS’s are limited to a five-to-15 kilometer (3.2-to-9.6 mile) out-and-return mission: the Silent Falcon can do 100 and spend five to seven hours in the sky at a stretch. This can be of great service to officers looking for a lost hiker or a fleeing felon.
Easing requirements for a ground crew, Silent Falcon’s autopilot system can maintain a pre-planned flight path, Brown referring to human pilots as “weak servos.”
For future development and enhancements, the open-interface bus architecture on board allows easy inclusion of new systems. Considering currently available sensors and recording devices, we might be making medical sweeps of neighborhoods in the near future.
What happened to Solar Impulse 2’s batteries on those long five days and nights over the Pacific? It took months of enforced downtime in Hawaii to have new batteries made, sent from Korea, installed, tested, and flown again. Could the plane have completed the flight on the original batteries?
Full-scale testing of SI2 battteries after addition of cooling system and before its departure from Hawaii
Kokam, manufacturer of the airplane’s cells, has released new information that provides details of the drive system and relieves a few lingering anxieties. An over-riding concern was that batteries overheated on the Japan to Hawaii part of the mission, topping out at 50 degrees Centigrade (122 degrees Fahrenheit) – above their design temperature. Your editor has thought deeply about what Andre’ Borschberg must have gone through every day of the five over the Pacific, seeing the temperatures on the four battery packs climbing as he pointed the airplane’s nose up in its saw tooth flight profile.
Borschberg explained that stress in a comment on SI2’s blog. “”I feel exhilarated by this extraordinary journey. I have climbed the equivalent altitude of Mount Everest five times without much rest. The team at the Mission Control Center in Monaco was my eyes and my ears. The MCC was battling to give me the possibility to rest and recover, but also maximizing the aircraft’s energy levels and sending me trajectories and flight strategies simulated by computer. This success fully validates the vision that my partner Bertrand Piccard had after his round-the-world balloon flight to reach unlimited endurance in an airplane without fuel.”
Kokam’s Z-fold construction would add surface area to allow more interaction of active materials
Concern, intense monitoring and precise directions enabled the pilot, craft and the four 38.5 kilowatt-hour battery packs to make it through five days and nights of high tension. Kokam’s “Ultra High Energy NMC battery packs” one per motor gondola, have a total of 154 kilowatt-hours of energy storage. The 150 Amp-hour cells made 17 flights totaling 26,744 miles (43,041 kilometers), fed by the 17,248 silicon solar cells on the wings, fuselage and horizontal stabilizer. Those cells produced 11,000 kWh of electricity during the around-the-world voyage.
The lithium nickel manganese cobalt cells produce high energy, sometimes associated with a propensity for thermal runaways. If the cobalt would lead to that, the manganese seems to act as a butter to prevent such problems, and NCM chemistry has a good safety record. The cells’ 96-percent efficiency keeps helps reduce temperatures during charging, and the pouch-type configuration provides a larger surface area to disperse heat than that available to prismatic or cylindrical cells..
Solar Impulse technicians decided to remove the battery packs when the airplane landed in Hawaii. Testing in Germany, where the batteries are packaged for use in SI2, found the cells were undamaged even after exposure to higher than normal temperatures, and had lost only that capacity they would have in more normal circumstances.
Large area presented by pouch cell allows battery to act as large heat sink
Andre’ Borschberg explained the SI2 team did not blame the batteries for the mid-journey hiatus. “When you are designing an experimental aircraft every additional system is a potential source of failure, and that is why we had not initially integrated a cooling system. As we had the time in Hawaii to replace the batteries, we decided to integrate the cooling system to give the airplane more flexibility, especially in very high temperature environments. The overheating problem was in no way related to any issue with Kokam’s batteries, which have delivered excellent performance for Solar Impulse 1 and on every leg of the flight with Solar Impulse 2, supporting our record- breaking circumnavigation of the globe.”
SI2’s batteries were subjected to extremes of temperature and multiple days of uninterrupted charging and discharging, and still managed to perform at high levels of performance and reliability. This in itself should provide encouragement to others now designing future electric aircraft.