A European-based consortium of academic and industrial groups take a very old idea, add a plasma system that seems to be nearly science fiction, whip them together and create quiet, efficient, vector-controlled flight.  That’s the promise, although it seems a bit much to take in all at once.  But the folks at the ACHEON (Aerial Coanda High Efficiency Orienting-jet Nozzle) project seem to think they have a potential winner here.  ACHEON represents two other acronyms, so let’s define those first.

The original idea for the project was part of H. O. M. E. R., not of the Simpsons, or even of epic Greek poetry, but of the “High-speed Orienting Momentum with Enhanced Reversibility” variety.  Combine that with P. E. A. C. E., the “Plasma Enhanced Actuator for Coanda Effect” with a low moving-parts count, and you get a method for enhancing flow, increasing thrust and vectoring that thrust for smoother, quieter rides and better maneuverability.

Aerospazio Campania thinks the key strengths of ACHEON “are the absence of moving elements, … control simplicity, a high precision, a very fast response, a consistent reliability and the possibility to work with any fluids (gases, liquids and mixes).”

“The result – summarizes Prof. Antonio Dumas, project supervisor – will enable [directing thrust flow] with an angle that can be adapted to any flight condition in a prompt and dynamic way, with very reduced response time ([hundredths]of a second). The possible implications for aeronautics are clear: vertical take-off and landing, reduction of spaces for airport operations, a better maneuverability, the elimination of traditional aerodynamic appendages, a better aerodynamic efficiency and low [fuel] consumption would be achieved by means of using the ACHEON device”.

Henri Coanda's 1910 cold jet-powered airplane was a demonstration of his named effect.  Unfortunately, it crashed and burned on its first flight

Henri Coanda’s 1910 cold jet-powered airplane was a demonstration of his named effect. Unfortunately, it crashed and burned on its first flight

Going back to the beginning, Henri Coanda was a Romanian inventor who probably owed his life to not wearing a seat belt.  “It was on 16 December 1910. I had no intention of flying on that day. My plan was to check the operation of the engine on the ground but the heat of the jet blast coming back at me was greater than I expected and I was worried in case I set the aeroplane on fire. For this reason I concentrated on adjusting the jet and did not realize that the aircraft was rapidly gaining speed. Then I looked up and saw the walls of Paris approaching rapidly. There was no time to stop or turn round and I decided to try and fly instead. Unfortunately I had no experience of flying and was not used to the controls of the aeroplane. The aeroplane seemed to make a sudden steep climb and then landed with a bump. First the left wing hit the ground and then the aircraft crumpled up. I was not strapped in and so was fortunately thrown clear of the burning machine.”

“Jet blast” seven years after the Wrights’ first flights may seem an anachronism, but Coanda was 30 years ahead of Frank Whittle, the British designer widely credited with the first jet engine.  It seems even odder that the airplane he crafted for the flight was all wood, beautifully crafted plies wrapped around the tubular fuselage.  The heat would have come from the exhaust of the 50-hp, four-cylinder engine driving the compressor.

The Coanda effect, named for the intrepid attempted flyer, has to do with that simple science experiment we show kids in grade school.  Its definition seems simple enough. Coanda Effect: A moving stream of fluid in contact with a curved surface will tend to follow the curvature of the surface rather than continue traveling in a straight line.

Water flowing around spoon is simple visualization of Coanda effect

Water flowing around spoon is simple visualization of Coanda effect

Beyond Coanda’s initial attmpts, others have attempted to use the underlying phenomenon in aircraft.  Otto “Pete” Bartoe in the 1970s created the Ball-Bartoe JW-1 “Jetwing,” now hanging in Denver’s Wings Over the Rockies Air and Space Museum.  The airplane, powered by a Pratt & Whitney JT-15D1 turbofan engine, could reach 400 miles per hour, and hang in the air at around 40 mph.  Harold “Fish” Salmon, Lockheed’s famous test pilot, flew the airplane, with Bartoe flying chase at lower speeds in his Piper Super Cub.

Ball-Bartoe JW-1 hovering above floor at Denver's Rocky Mountain Air & Space Museum

Ball-Bartoe JW-1 hovering above floor at Denver’s Rocky Mountain Air & Space Museum.  Slotted, heavily-flapped wing took advantage of Coanda effect

What made this 10:1 speed ratio possible?  70-percent of the wing was “blown” by the jet exhaust, neatly ducted to flow over its upper surface and under a small augmentor wing.  The upper wing helped draw air through the resulting slot and increase lift, while the Coanda effect over the highly flapped main wing allowed slow speed under control.

Because Coanda’s 1936 patent showed an inverted bowl being lifted by air blowing around the circumference of the bowl, several attempts have been made with “flying saucers,” including an Avro Canada vehicle notorious for its appearances in newsreels of the late 1950s.

The idea was good, but the execution was flawed.  “The Avro Canada VZ-9 Avrocar was a VTOL [Vertical Take Off and Landing] aircraft developed by Avro Aircraft Ltd. (Canada) as part of a secret U.S. military project carried out in the early years of the Cold War.  The Avrocar intended to exploit the Coandă effect to provide lift and thrust from a single “turborotor” blowing exhaust out the rim of the disk-shaped aircraft to provide anticipated VTOL-like performance. In the air, it would have resembled a flying saucer.”

Flight testing revealed problems with thrust and controlability, leading to the machine’s ungainly appearances in numbers of newsreels.

C-17 III lifting off in 2010 on 50-50 mix of jet fuel, biofuels consisting of half rendered beef tallow and half Fischer-Tropsch liquified coal or natural gas

C-17 III lifting off in 2010 on 50-50 mix of jet fuel, biofuels consisting of half rendered beef tallow and half Fischer-Tropsch liquified coal or natural gas.  Jet blast goes over significant portions of upper surface of flaps.  Photo from www.makebiofuels site

More recently and successfully, the Boeing (formerly McDonnell-Douglas) C-17 Globemaster uses “blown flaps” that exploit the Coanda effect; they were “developed by a team of researchers at NASA Langley Research Center in the mid-1950s. The ‘externally blown flap’ or ‘powered-lift system’ enables the airplane to make slow, steep approaches with heavy cargo loads. The steep approach helps pilots make precision landings with the aircraft, touching down precisely in the spot desired on limited runway surfaces. This was accomplished by diverting engine exhaust downward, giving the wing more lift. In the flap system, the engine exhaust from pod-mounted engines impinges directly on conventional slotted flaps and is deflected downward to augment the wing lift. This allows aircraft with blown flaps to operate at roughly twice the lift coefficient of that of conventional jet transport aircraft. “

Not to be outdone, the Russians fielded the smaller, but agile, AN-72 and AN-74, even more apparently “blown wing” aircraft.”  Their ability to fly from short fields is enhanced by their high-lift, contributed to by the Coanda effect.

In the next segment, we will look at the Acheon Project itself, with the promise that modern electronics can add to a 105-year-old technology.  How might this blend of old and new contribute to aircraft that will make pocket airparks a reality?

{ 0 comments }

Reported widely late last year as a “Junkyard Wars” contraption, University of Toronto researcher Illan Kramer’s spray rig for coating just about anything with a thin film of colloidal quantum dots (QCDs) offers the potential for making Kramer’s hopes come true.  “My dream is that one day you’ll have two technicians with Ghostbusters backpacks come to your house and spray your roof.”

Junkyard Wars look belies use of supercomputer, finished product one-atom thick

Junkyard Wars look belies use of supercomputer, finished product one-atom thick

Kramer is a post-doctoral fellow with The Edward S. Rogers Sr. Department of Electrical & Computer Engineering at the University of Toronto and IBM Canada’s Research and Development Centre.  His spray equipment, composed of a “spray nozzle used in steel mills to cool steel with a fine mist of water, and a few regular air brushes from an art store,” manages to spread colloidal quantum dots with the precision usually found in atomic layer deposition managed in laboratory or carefully-controlled manufacturing conditions.

He admits to the unaesthetic look of the setup, but notes that the $1,000 sprayLD system (a play on the manufacturing process called ALD, or atomic layer deposition), can take the place of expensive batch manufacturing processes normally used to coat materials.

His sprayLD ” blasts a liquid containing CQDs directly onto flexible surfaces, such as film or plastic, like printing a newspaper by applying ink onto a roll of paper. “    The solar-collecting QCDs “could be used to coat all kinds of weirdly shaped surfaces, from patio furniture to an airplane’s wing. A surface the size of your car’s roof wrapped with CQD-coated film would produce enough energy to power three 100-Watt light bulbs—or 24 compact fluorescents.”  The implications for an airplane, with its large wetted area covered with the film include range extension for an electrically-powered aircraft, or all-day soaring for a motorglider.

Kramer has reported his progress in papers in the journals Advanced Materials and Applied Physics Letters, showing “that the sprayLD method can be used on flexible materials without any major loss in solar-cell efficiency.”

CBC reports,  “’As quantum dot solar technology advances rapidly in performance, it’s important to determine how to scale them and make this new class of solar technologies manufacturable,’ said Professor Ted Sargent (ECE), vice dean, research in the Faculty of Applied Science & Engineering at University of Toronto and Kramer’s supervisor. ‘We were thrilled when this attractively manufacturable spray-coating process also led to superior performance devices showing improved control and purity.’”

The University reports, “In a third paper in the journal ACS Nano Letters, Kramer and his colleagues used IBM’s BlueGeneQ supercomputer to model how and why the sprayed CQDs perform just as well as—and in some cases better than—their batch-processed counterparts.”

The Canadian Broadcasting Company (CBC) reports that the spray-on’s efficiency is not quite the 10 percent needed to become commercially viable.

“’We’re close,” Kramer says. Their best measured efficiency is 8.1 per cent.  So, we’re getting there.’”

{ 0 comments }

Ken McKenzie, listed as Deputy Chairman of Airbus US, has served as Vice President for Airbus Customer Services and as Chief Operating Officer for Airbus Americas, Inc.  This high-powered individual comes across as a relaxed, congenial soul, though, and led attendees at the ninth annual Electric Aircraft Symposium through an overview of developments in light electric aircraft to come from the aviation giant.

The e-Fan is the most visible effort for Airbus’s electric aircraft work so far, but the company is intent on carrying out a full E-aircraft program as part of its commitment to the European Commission’s Flightpath 2050 program,. which bullet-points these important goals for the next 35 years:

“1. In 2050 technologies and procedures available allow a 75% reduction in CO2 emissions per passenger kilometer to support the ATAG (Air Transport Action Group) target10 and a 90% reduction in NOx emissions. The perceived noise emission of flying aircraft is reduced by 65%. These are relative to the capabilities of typical new aircraft in 2000.

“2. Aircraft movements are emission-free when taxiing.

“3. Air vehicles are designed and manufactured to be recyclable.”

McKenzie explained that the Airbus Group is composed of three divisions: Airbus, which builds airliners and is responsible for development of the electric flight program; Airbus Defense and Space, and Airbus Helicopters.

In trying to meet future demands for environmentally-friendly aircraft, Airbus sees several benefits.  Electric airplanes tend to be clean, quiet, efficient, compact and reliable.  That compactness is scalable, though, and lessons learned from light aircraft can be applied to larger variants.  The quietness allows airports to stay open later without disturbing neighbors.

Penalties, though, include problems of energy storage, weight and cost, and an uncertain certification path.  Carrying a large battery weight per person reduces the commercial viability of an aircraft, and dotting all the “i’s” in a certification program can be fraught with “gottchas” that end up being detrimental to long-term success.

Using light aircraft for development efforts helps side-step some of these difficulties.  The smallest example was the Cri-Cri, designed by one of the Concorde’s engineers, and which flew originally with small chainsaw engines on the stalks protruding from the plane’s nose.  Airbus’s electric version used four each 5.5 kilowatt motors, two per stalk – one pushing and one pulling.  The tiny airframe’s size allowed flights of airshow demonstration duration.

The "Green" Cri-Cri may seem a strange airplane on which to start in electric aviation, but its four 5.5 kW motors provided data at low-budget costs

The “Green” Cri-Cri may seem a strange airplane on which to start in electric aviation, but its four 5.5 kW motors provided data at low-budget costs.  Note the four “throttles” on the left side of the cockpit used to control the four Rotex motors

A Super Diamond hybrid went through two iterations, showing off a Siemens motor and Wankel-type internal combustion engine to provide fuel economy and extended range.

The e-Fan is the first purpose-built electric aircraft from Airbus, and can be seen as a technology demonstrator for what is to come.  Its e-Thrust propulsion includes a well-monitored and regulated battery system, telemetry to keep the pilot and ground-based support personnel informed, e-FADEC (Full Authority Digital Electronic Control), and a landing gear driven by 100-kilometer per hour (62 mph) electric motors.  McKenzie pointed out that these provide for taxiing without the use of the fans and help accelerate the airplane during takeoff.

The battery management system can isolate individual four-Volt cells from the 120-cell packs to allow continued operation even with the failure of one or more cells.  This kind of control also reduces the possibility of thermal runaways.

The e-Fan can cruise at 160  mph with a  noise level less than 60 dB.  Its lift-to-drag ratio of 16:1 helps conserve energy and after 78 test flights totaling 38 hours, the airplane has been trouble-free and given test personnel loads of useable data.

New assembly facility in Pau, France will resemble e-Fan canopy

New assembly facility in Pau, France will resemble e-Fan canopy

McKenzie shared that one sale to Delta of a large Airbus makes more money than all sales of all e-fans will in 20 years.  In spite of this apparent neglect for the bottom line, their use for development and research will be invaluable to the company.  Airbus is looking at e-Thrust distributed propulsion with Rolls-Royce, for instance, for much larger aircraft.  The firm is working on electric helicopters and as noted, commercially viable electric airliners.

Immediate goals for the two e-Fans under development include a reduction from a 30-minute recharge time to only five minutes.  This will be essential to using the two-seater as a trainer, since time on the ground does not make the flight school any money.  American trainers need to be in the air 11 hours a day for student work, according to McKenzie.

The 4.0, four-seat general aviation craft will be hybrid with up to five hours flight duration, enabling long-range cross-country flights.  The e-Fan will need to be certified under FAR Part 23 rules, necessary to allow its use for flight training in the U. S.

Assembly facility can accommodate almost the first year's anticipated production at once

Assembly facility can accommodate almost the first year’s anticipated production at once

To reduce costs and expedite production, much of the airframe for these craft will not be carbon fiber, but less expensive fiberglass.  Airbus is working with partners to answer battery questions, even examining aluminum –air batteries.  The company is partnered with Safran (already having assisted with electric landing gears for taxiing airliners), Zodiac and Evtronics.

Airbus has formed Voltair SAS, located in Bordeaux France, with an assembly facility to be built in the town of Pau.  Look for the 2.0 to be flying by 2017, with the 4.0 making its debut shortly thereafter.

Ken McKenzie electrical propulsion needs to find a market to make it work.  It seems that Airbus is willing to seek that market, even with loss leaders on the light aircraft side.  That will surely lead to the development of efficient, well-proven components that will find their way into the general aviation market in time.  That is surely something for which Airbus deserves our thanks.

{ 1 comment }

HZB Makes H2 With Fool’s Gold

Hydrogen, two atoms of which are in every molecule of water, is wildly abundant, but elusive to extract for our transportation needs.  Common means of pulling the H2 from the H2O used fossil fuels, and thus negate the good intentions for its use.  Several people have tried cleaner means of “splitting water,” including Daniel Nocera of MIT and Harvard, and researchers around the world, including those in the Netherlands and Germany.  One notable recent accomplishment at the HZB (Helmholtz Zentrum Berlin) Institute for Solar Fuels involves a new composite photocathode that generates H2 “with high quantum efficiency” using sunlight.

The Institute says, “The photocathode consists of a thin film of chalcopyrite produced by HZB/PVcomB coated with a newly developed thin film of photo-resistant titanium dioxide (TiO2) containing platinum nanoparticles.”

Layering of HZB artificial photosynthesis photocathode

Layering of HZB artificial photosynthesis photocathode

Of course your editor, who wishes he had taken better notes in chemistry class, Googled the unfamiliar term.  A University of Michigan note on CuFeS2 – Copper Iron Sulfide explains, “Chalcopyrite was the mineral upon which Bronze Age civilizations were built. Within the last century, it also became the mineral foundation for our modern electrical age. Our primary source of copper, chalcopyrite’s name comes from the Greek words ‘chalkos’ and ‘pyrites’, which respectively mean ‘copper’ and ‘striking fire’. With its metallic luster and bright golden color, chalcopyrite can fool people into thinking it is gold. It is one of two minerals, the other being pyrite, that are commonly known as ‘fool’s gold’”.

With its pricey components, the layer covering the chalcopyrite film protects it from corrosion and acts as a catalyst, speeding formation of hydrogen and acting as a photodiode showing “photoelectric current density and voltage comparable to those of a chalcopyrite-based thin film solar cell.”

Electrodes used in splitting water, such as platinum or platinum-iridium alloys, are usually from the pricier side of the periodic table.  Despite the platinum nanoparticles in the coating over the chalcopyrite, the “fool’s gold” photocathode helps keep the price of these devices in a moderate range.

The polycrystalline TiO2 film contains a small amount of platinum in the form of nanoparticles, and produces “under sun light illumination a photovoltage of almost 0.5 volts and very high photocurrent densities of up to 38 mA/cm2; secondly, it acts as a catalyst to accelerate the formation of hydrogen, and finally, it is chemically protected against corrosion as well.”

The coating, developed by Anahita Azarpira during her doctoral studies in a team headed by Assoc. Prof. Thomas Schedel-Niedrig, uses a chemical vapor coating technique (sprayed ion-layer gas reaction/Spray-ILGAR) developed and patented at the HZB Institute for Heterogeneous Material Systems (EE-IH).

To make the coating , “titanium dioxide and platinum precursors are dissolved in ethanol and converted to a fog using an ultrasonic bath.”  As shown in the video, the “fog” spreads over the heated chalcopyrite substrate and “grows” a thin film in time, coating the substrate and embedded platinum nanoparticles.

Azarpira and her colleagues varied the amount of platinum in the precursor solution to optimize the properties of the novel composite photoelectrode device, finding best performance with about five-percent platinum (H2PtCl6) in the precursor solution   Schedel-Neidig reports, “ More than 80 percent of the incident visible sunlight was photoelectrically converted by this composite system into electric current available for the hydrogen generation, ” losing little light and attaining a high quantum efficiency.

That means little light is lost and the quantum efficiency is virtually very high. A recent article reports the composite shows high long-term stability over 25 hours and reveals large photoelectrocatalytic activity of about 690 hydrogen molecules produced per second and per active center at the surface under illumination.

As with all such research, much remains to be done.  1.8 Volts required between the composite photocathode and a platinum counter electrode still comes from a battery. Hence the solar-to-hydrogen efficiency has to be clearly improved.

Schedel-Niedig remains optimistic, saying the team “demonstrate[d] the feasibility of such future-oriented chemical robust photoelectrocatalytic systems that have the potential to convert solar energy to hydrogen. “ Working with a company in Schwerin, the team developed and tested a demonstrator device for solar hydrogen under the Light2Hydrogen project.

The team reports on their research in their paper, “Efficient and Stable TiO2:Pt-Cu(In,Ga)Se2Composite Photoelectrodes for Visible Light Driven Hydrogen Evolution. “ in the journal, Advanced Energy Materials.

Authors include Anahita Azarpira, Michael Lublow, Alexander Steigert, Peter Bogdanoff, Dieter Greiner, Christian A. Kaufmann, Martin Krüger, Ullrich Gernert, Roel van de Krol, Anna Fischer, and Thomas Schedel-Niedrig.

The abstract for that paper reads: “Novel thin film composite photocathodes based on device-grade Cu(In,Ga)Se2 chalcopyrite thin film absorbers and transparent conductive oxide Pt-implemented TiO2 layers on top are presented for an efficient and stable solar-driven hydrogen evolution. Thin films of phase-pure anatase TiO2 are implemented with varying Pt-concentrations in order to optimize simultaneously i) conductivity of the films, ii) electrocatalytic activity, and iii) light-guidance toward the chalcopyrite. Thereby, high incident-photon-to-current-efficiencies of more than 80% can be achieved over the full visible light range. In acidic electrolyte (pH 0.3), the most efficient Pt-implemented TiO2–Cu(In,Ga)Se2composite electrodes reveal i) photocurrent densities up to 38 mA cm−2 in the saturation region (−0.4 V RHE, reversible hydrogen electrode), ii) 15 mA cm−2 at the thermodynamic potential for H2-evolution (0 V RHE), and iii) an anodic onset potential shift for the hydrogen evolution (+0.23 V RHE). It is shown that the gradual increase of the Pt-concentration within the TiO2 layers passes through an efficiency- and stability-maximum of the device (5 vol% of Pt precursor solution). At this maximum, optimized light-incoupling into the device-grade chalcopyrite light-absorber as well as electron conductance properties within the surface layer are achieved while no degradation are observed over more than 24 h of operation.”

{ 0 comments }

Singapore Firm, Boeing Team Up on Hydrogen

EV World reports that a Singapore-based company, Horizon Energy Systems, has test flown the world’s first hydrogen powered quadracopter, a small UAV that is claimed to fly for hours, instead of the minutes a lithium battery pack would provide.

The report asks that tantalizing question for all who suffer from range anxiety, especially while in flight.  “What if you could increase flying time by a factor of ten? Instead of half-an-hour, you could keep the UAV flying for five hours, and then charge it in a couple minutes time? That’s what Singapore-based Horizon Energy Systems is promising. They have developed micro fuel cells that can be fueled by three types of hydrogen storage systems from small compressed gas cylinders to ‘on-demand’ hydrogen generation chemical cartridges rated at 700 Watt-hours per kilogram (Whr/kg), significantly higher than the best lithium batteries.”

Horizon's Hycopter can fly for hour on a dollop of hydrogen

Horizon’s Hycopter can fly up to four hours on a dollop of hydrogen

Horizon’s Hycopter micro UAV quadracopter stores 120 grams (0.26 pounds) of hydrogen in its structure, equivalent to three kilograms (6.6 pounds) of lithium batteries. According to EV World, “Since the Hycopter has less weight to lift, it can fly longer: the company claiming up to four hours of flight time.”

As noted above, Horizon Energy Systems produces three different approaches to storing H2:

  1. Gaseous fuel storage of compressed hydrogen. This option costs $1 per hour for 200 Watts, and offers the least system complexity if there is enough room in the airframe to accommodate the tanks.
  2. “On demand” hydrogen generation using liquid chemical cartridges. This option offers the same energy available but in half the volume of the tanks of compressed H2.  It’s also slightly lighter and “loses” the weight of fuel as it is consumed.  This, of course, would be important in a small UAV, which might weigh no more than a few pounds.
  3. “On demand” hydrogen generation using solid chemical cartridges. Horizon explains that there are no catalysts required, and the chemicals offer unlimited storage duration.

From their specification sheet, we see that a one kilowatt AeroStak system, complete with controller, would weight 2.25 kilograms, or 4.95 pounds.  The system also requires an external 36 Volt power supply. Stack size of the 50-cell unit is 252 x 126 x 190 millimeters (9.92 x 4.96 x 7.48 inches).  Advertised as “10 times lighter and smaller than other Horizon fuel cells,” how do Aerostaks stack up against lithium-ion batteries?

Your editor chose to make a 10 kW stack as a comparison unit for the Eck-Geiger lithium-ion battery pack used in many ultralight motorgliders, such as the Swift.  10 one-kW stacks could be arranged as a block about 10 x 15 x 7.5 inches, or possibly in a string that could be 100 x 5 x 7.5 inches, or in other configurations that would fit into an airframe.  We’ll stick with the first arrangement, since that comes close to the Flytec’s battery module size.

Using Horizon’s ratio of 0.26 pounds of hydrogen equaling 6.6 pounds of lithium batteries (energy density unspecified), it would take about 2.16 pounds of stored H2 to equal a Flytec 100 Amp-hour battery pack weighing 25 kilograms (55 pounds), according to Flytec’s 2015 listings.

This would give over an hour’s flight, based on Gerard Thevenot’s flight across the English Channel in 2009.  His La Mouette hang glider used the Eck-Geiger HPD-10 motor and consumed 550 grams, or about 1.3 pounds of hydrogen per hour.  2.16 pounds of H2 would have provided 1.66 hours of flight, a comfortable margin for that 22-mile trip.

It’s hard to judge whether the Horizon systems would give a 10-fold increase in endurance over batteries – the numbers don’t seem to indicate quite that, but the system does allow clean running, even though at this point, possibly higher operating costs than lithium batteries.  Their quoted $1 per hour for 200 Watts would equal $50 per hour for the full output of a 10 kW motor.

Such stacks and their attendant hydrogen-generating systems could be used as the sole means of powering an aircraft, or possibly in conjunction with a conventional battery pack as a range extender.  Depending on unit cost and availability, Horizon Energy Systems’ packs may provide an alternative worth exploring, although one may be tempted to find a cheaper fuel source.

Boeing thinks it’s worth exploring, although in a context where expenses may not be a primary concern.  As these things become more common, costs will probably come down, and that will be a benefit to all of us.

{ 2 comments }

Salting the Battery

Ideally, battery materials should be abundant, cheap, and safe.  NaCl (salt) seems to manage three out of three of these, but can it manage the energy and power density of less abundant and more expensive materials such as lithium?

Faradion, an English enterprise specializing in “advanced energy storage solutions,” thinks that the salt of the earth may indeed be part of the secret sauce in their new battery.  Initial applications will probably be in large energy-storage systems associated with renewable energy, but forward-looking statements (we used to call them predictions) show the potential for lighter, smaller batteries that could compete with lithium-ion cells.

Faradion foresees energy and power densities competitive with the best lithium-ion batteries

Faradion foresees energy and power densities competitive with the best LiFePO4 batteries

Since the introduction of new technology does not usually come from a single source, Faradion is partnered with co-funders Innovate UK, the UK’s innovation agency; Williams Advanced Engineering and the University of Oxford.

The group is building 3 Amp-hour prismatic cells “containing Faradion’s novel cell chemistry, and are being incorporated into battery packs by Williams.”  This will require no major changes in existing battery manufacturing lines.

Faradion’s chairman, Chris Wright, explains.  “Sodium‑ion does everything lithium‑ion does, but cheaper,” he says. “If a manufacturer already has a lithium‑ion plant, there is no incremental capital cost because it uses the same equipment. According to Argonne National Lab’s BatPaC data model, a 16kWh sodium‑ion pack is 30% cheaper.”

Faradion 12-cell module with battery management system (BMS)

Faradion 12-cell (3 Ah each) module with battery management system (BMS) designed by Williams Advanced Engineering

In Faradion’s PowerPoint presentation on Na-ion batteries, lithium forms about 0.005 percent of the earth’s crust, while sodium constitutes about 2.6 percent (the sixth most abundant element – even though it never appears naturally as an element), and can be produced from simple drying of seawater (Lewis and Clark left a drying cairn in Seaside, Oregon where they produced salt for their animals and themselves). Because of this relative availability, a carbonate form of lithium costs about $7,000 per ton, while an equivalent weight of sodium carbonate costs less than $200.  But, sodium has an ionic radius about 1/3 bigger than that of lithium, and because of that size cannot use inexpensive graphite as an anode in Na-ion batteries.  Even with that limitation, material costs end up being lower overall.

Again, the manufacturing end retains all the techniques used in lithium batteries.  Best Magazine reports, “’If someone wanted to convert a line to sodium‑ion there is literally nothing that needs to be changed apart from the materials used,’ says Chief Technology Officer Jerry Barker. ‘The technicians running the line wouldn’t notice any difference.

“’We double‑side coat the anode and cathode; layer the materials step‑by‑step with a separator, we electrolyte‑fill for the porosity in the electrodes and separator; there are two or three formation cycles; we degas; then we make the final seal.

“’We could jelly‑roll for 18650 cells or use a Z‑fold arrangement of a continuous layer of separator instead of individual stacks with a square separator, but whichever process we would choose it is exactly the same process as for lithium‑ion.’”  This ability to use existing process lines is similar to the use of existing semiconductor chip manufacturing lines by Sakti 3, and will enable quick startups and technology transfer.  The same techniques used in their NaCl batteries will work with improved lithium iron phosphate (LiFePO4) batteries, for which Faradion has also developed chemistries.  Their manufacturing techniques will lower costs for these cells, according to the company.  Lower prices will come from the lower costs of primary materials, and the ability to use existing facilities with little or no modification.

Test e-bike with large Faradion battery modules (for ease of manufacture on prototype)

Test e-bike with larger-than-necessary Faradion battery modules (for ease of manufacture on prototype)

Getting into a market, though, presents some difficulties.  The firm explains that entry into the automotive market might be slowed by problems of obtaining licenses and clearing regulatory hurdles, so it’s looking at starting in cargo e-bicycle power packs, and domestic solar energy storage for homes and communities.

With a readily available non-volatile material, Na-ion batteries seem to have a future in battery development.  The leaders at Faradion think they can reach energy densities that would make their batteries attractive to EV developers.  We wish them luck.

{ 0 comments }

EAS IX: JoeBen Pulls off a Hat Trick

JoeBen Bevirt, founder and head of Joby Aviation and Joby Motors , is obviously a workaholic, and not only gave a talk at EAS IX, but had an example of his Lotus unpiloted aerial vehicle at the AUVSI (Association for Unmanned Vehicle Systems International) conference in Atlanta, Georgia on the same weekend.

Joby's Lotus UAV showing split-tip wing that transforms into a large tip rotor

Joby’s Lotus UAV showing split-tip wing that transforms into a large tip rotor

Two weeks before that, his demonstration wing for the LEAPTech program was speeding across the desert at NASA’s Armstrong Flight Research Center (AFRC), Edwards Air Force Base in California. JoeBen told Symposium attendees all about his S2 personal aerial commuter and LEAPTech, a joint development with NASA.

Part of the LEAPTech program has included building a truck platform for testing the 18-motor wing.  This is a fascinating bit of engineering in itself.

YouTube does not yet show a test run with the truck and wing, but this news item includes it here.

LEAPTech (Leading Edge Asynchronous Propeller Technology) is a NASA Team Seedling Award under the Convergent Aeronautics Project of ARMD (Aeronautics Research Mission Directorate). The team is made up of LaRC, or Langley Research Center (lead design), AFRC (lead integration), ESAero (Data Acquisition and Instrumentation) and Joby Aviation (Truck Design/Fabrication, wing design/fabrication, motor design and system power).

The S2 is a two-seat vertical takeoff and landing (VTOL) aircraft that seems like an expansion of Joby’s earlier Monarch, a single-seat machine. Its 12 rotor/propellers would carry the occupants on an up-to-200-mile, autonomous flight to destinations of their choosing.

Joby Aviaton's S2 in high-speed cruise

Joby Aviaton’s S2 in high-speed cruise

JoeBen describes heliports as expensive, noisy, and perceived as dangerous by the general public. For those reasons, they are often rejected by city and neighborhood planners. But he claims his VTOL electric aircraft could be 100 times quieter than a helicopter, and benefit from its rotor blade tip speeds in hover of 350 feet per second, well under the supersonic threshold.

Making a direct comparison, JoeBen says the S2 has a higher disk loading and higher mass than a Robertson R22,but also a higher cruise speed and a lower, much less noisy, rotor tip speed. With its 12 motors, it would be safer than a helicopter, with extreme redundancy and fail-safe systems.

Such a machine would appeal to air taxi operator, and maybe even offer transportation alternatives like Uber a vehicle that could expand its operations to 70 to 250 mile hops. With an operating cost of 2.00 per mile, operators could be profitable at today’s taxi rates. Comparing rates, a taxi ride from San Francisco International Airport (SFO) to Fremont, California is around $55.00 for the 32.8 mile ride by the most direct route, and will take at least 38 minutes. Bay Area Rapid Transit charges $11.25 for the same trip, but takes over an hour and 40 minutes. A direct, air-miles route is 28 miles, costing $56.00 in operating costs, and taking less than 15 minutes. People will be willing to pay a modest premium for the convenience and speed of the trip.

These advantages would grow on longer routes, where the airplane’s high speed would enhance point-to-point times. With Dr. Seeley’s on-airport pocket airparks, the convenience level would be as great as that of finding a ground taxi, or probably greater than fighting one’s way to a mass-transit stop. With all these projects progressing rapidly, JoeBen and his team including Alex Stoll and Edward Stilson, among others, are helping define aviation’s future. It should be a green, quiet future.

{ 0 comments }

Getting Sideways in SI2

Any pilot who’s had to land an airplane at its crosswind limit knows that each airplane has a point where its controls cannot overcome the sideways force, and one cannot perform the final level, straight-down-the-runway touchdown.  Usually, pilots do a go-around or find a more wind-oriented runway.  Solar Impulse’s explanation under the video tells why this is almost impossible under deteriorating conditions with a craft as huge and slow as SI2.

Take note of the control inputs test pilot Marcus Scherdel makes in the final moments of the August 30, 2014 flight.

The Solar Impulse team released this video in the last week, perhaps to explain why the crew is waiting for a positive “weather window” before embarking on a planned five-day epic voyage from Nanjing, China to Hawaii.

“Solar Impulse was still in flight test phase when Markus Scherdel, the experienced test pilot, was put to a challenge by strong crosswinds during landing. Si2 returned from a flight to Payerne Airfield and performed a planned low approach before landing. A go around and subsequent approach takes on average 20 minutes, during which the winds increased significantly and unexpectedly to 4 knots (4.6 mph) crosswind component. The pilot had no other option but to land despite the situation as the weather was rapidly deteriorating. Right before landing, the pilot got gust from the side, blowing the plane off the runway to the right. He then needed to correct back to the center line. Markus never lost his smile, although he was imposed a great work load, trying to avoid landing next to the runway or losing balance. This demonstrates how Solar Impulse is sensitive to turbulences.”

{ 0 comments }

EAS IX: Phil Barnes Double Header

Phil Barnes, aviation consultant, opened each days’ sessions at this year’s Electric Aircraft Symposium: on Friday with a talk on dynamic soaring as taught by the birds, and on Saturday on regenerative power to keep a dynamic soaring aircraft in perpetual flight without any outside energy source other than the sun.

Phil has 31-years of experience in the performance analysis and computer modeling of aerospace vehicles and subsystems at Northrop Grumman. He has been to Antarctica twice to photograph and study the flight dynamics of the Albatross, lessons he applies to the ideals of dynamic soaring and energy retrieval in flight.

His Friday morning talk, “How Flies the Albatross,” discussed the flight mechanics of dynamic soaring, that mode of maintaining or gaining altitude from horizontal wind gusts, something the albatross uses to fly huge distances searching for food for itself and its family.  From the observations of well-known naturalists, he showed the bird “could soar against strong winds without a beat of its wings (Jacques Cousteau), something elaborated on by David Attenborough and first attested to by Isaac Newton (1725) and Lord Rayleigh (1883).

Barnes reports on his web site, “The albatross travels overall downwind faster than the wind. Indeed, the albatross circumnavigates Antarctica several times per year, in as little as 46-days per trip. Only with dynamic soaring can the albatross fly so fast and far.”  Going into the wind, the Albatross ascends into an increasing headwind, the essence of dynamic soaring.  With the boundary layer over the ocean an estimated 250 feet thick, these birds have more than enough “ceiling” in which to explore dynamic exploitation of the vertical gradients of a horizontal wind.

Others are thinking along the lines Phil Barnes discussed in his EAS talk.

Others are thinking along the lines Phil Barnes discussed in his EAS talk.  Oceanographer Phil Richardson created this “conceptual illustration of a robotic unmanned aerial vehicle soaring over the ocean, taking advantage if the same physics that an albatross does to fly fast and efficiently.” Photo: Phil Richardson, Woods Hole Oceanographic Institution

Barnes illuminates the physics of dynamic soaring with a simple explanation – riding with a model airplane in a car with a sunroof.  “Let’s say we are driving our car at 90 km/hr with the moonroof open. Just beneath the moonroof we hold a model airplane. Although the model at this point is traveling at 90 km/hr it has no airspeed, and thus no usable kinetic energy, relative to the air in the car. Were we to let go of the model it would fall to the floor of the car. If, however, we were to raise the model just above the moonroof, it would suddenly gain 90 km/hr. of airspeed and the corresponding amount of kinetic energy. Once released, the model would convert its newfound kinetic energy into potential energy by climbing high in the sky.”

He uses dynamic soaring force diagrams, showing direct quantitative proof of Lord Rayleigh’s qualitative descriptions of the phenomenom, and explains the three orthoganal accelerations showing that Newton’s laws are applied in the bird’s soaring flight.  Including factors such as turn rate and modulated thrusts adds up to a complicated nine factors that help determine the success of the bird’s efficient exploitation of horizontal wind currents.

An albatross deals with this complex math and does something that would have driven our flight instructors wild – it holds its head level with the horizon, keeping its “sensor platform” constant with the plane of the horizon.  Phil notes that his simulation program (which readers can try out on Phil’s web site) keeps the head of his idealized bird level, something of which he is quite proud.

Phil concludes that wind gradients, not waves; and airspeed, not groundspeed, make dynamic soaring possible.  This type of soaring makes net progress in any direction – something the Albatross has mastered in its 50 million-year journey to perfection.

In the second-day opener, Phil was back to show the strong relationship between his studies of Albatross flight and the potential of regenerative flight, something that would enable nearly perpetual flight using electronics technology similar to that used on cars such as the Toyota Prius.

Phil Barnes Regenosaur, taking inspiration from the Albatross and the Toyota Prius

Phil Barnes Regenosaur, taking inspiration from the Albatross and the Toyota Prius

His Regenosaur comes from observation of Albatross flight, simulation of dynamic soaring and the thoughts of aerodynamicists such as Hermann Glauert and Paul MacCready, including Glauert’s early thoughts on wind turbines and ridge lift, and MacCready’s speculations on the possibilities of regenerative flight.

Barnse’s windprop combines the functions of a propeller and a wind turbine, and must be carefully designed to work in pinwheeling mode and derive the most thrust from a propeller based on the “Betz conditions,” named after A. Betz, who theorized minimum energy losses from lightly-loaded propellers as early as 1919.  The windprop would have eight blades carefully set for blade twist to satisfy Betz conditions, and drive a brushless motor/generator that could provide thrust, and then feed energy back to the aircraft’s batteries through a “six-pack” inverter-rectifier designed for efficient regeneration, actually amplifying the effects of the windprop.  These ideas are more fully explained in Phil’s presentation on his web site.

As always, Phil Barnes gave a thorough and challenging analysis of how to learn from nature and apply those lessons to a promising approach to perpetual flight.

{ 0 comments }

Goshawk Goes Electric

The GosHawk was conceived as an electric aircraft and technology has FINALLY caught up with it, according to designer Greg Cole. Its sailplane-like proportions allow it to fly with the smallest of power inputs, and real soaring is possible with the electric propulsion system completely shut down, Greg says.  This author finds it suits its namesake with a sporty nature and a natural beauty.

Flowing lines of Goshawk show strong design heritage from Windward Performance

Flowing lines of GosHawk show strong design heritage from Windward Performance, even in unfinished form.  Photo courtesy of Greg Cole

The GosHawk is also planned in two additional versions with internal combustion engines. The HKS 700E engine is a fuel-efficient two-cylinder unit seemingly ideal for motorgliders or touring gliders. His airplane with this engine’s 56 horsepower available can attain a 100 mile per hour cruise at a fuel consumption of 100 miles per gallon, or 200 passenger miles per gallon (pmpg). Greg also plans on using the ubiquitous Rotax in 85 BHP form.

Its empty weight of 510 pounds with the HKS powerplant shows the skills Greg’s company, Windward Performance achieves with pre-impregnated carbon fiber layups. Greg has crafted a 50.8 foot wingspan aircraft that weighs about 220 pounds less than a 65-hp Piper J-3 and still retains sailplane load limits (+5.3g / -3.0g). Part of this is due to the use of a modified version of the DuckHawk wing, designed for dynamic soaring in this single-seat high-performance sailplane. In two-seat service with a motor and batteries, it’s still stronger than a utility-class General Aviation craft.

GosHawk’s high never-exceed velocities (depending on model) demonstrate its excellent strength and verify its high-speed capabilities.  Its 38:1 lift-to-drag ratio at 46 knots (52.9 mph) and 130 feet per minute minimum sink rate at 46 knots (52.9 mph) highlight its aerodynamic cleanness.

Greg says, “We plan to retain the V, SV, and VNX designation started with the DuckHawk. V would be the very lightest (perhaps the most interesting) and with lower speed limits (120 KEAS* Vne, or l38 mph). The SV would have a 200 KEAS Vne and higher gross weight limits. The VNX would push the Vne up to 225 KEAS.”

Projected rate of climb at 700 pounds is 1,200 feet per minute at 85 knots (97.75 mph), a nice cruising climb while still clearing obstacles. On the other end, Goshawk’s stall speed of 42 knots (48.3 mph) enables short-field landings, especially with its low total mass.

Its side-by-side configuration makes it a good training platform, and its soaring capabilities will allow thermal, slope, and wave exploration. The motor can be restarted at altitude for self retrieval if required.

Greg’s electric propulsion system will enable the same performance and an hour’s endurance using currently-available batteries. The airplane is nearing completion at Windward Performance’s workshops in Bend, Oregon, waiting installation of its environmentally-friendly motor system.

Greg plans to offer three battery capacities in increments of 5 kilowatt-hours (kW-Hrs). Endurance with 5kW-Hr is 30 minutes, making GosHawk more of a self launching sailplane. Greg explains, “The full battery capacity, or load if we can say that, will dig into performance and add 180 pounds (90 pounds per 5 kW-Hr) to the weight but give it an almost usable range. Gross weights of the SV and Vnx versions will be 1,150 pounds. It is likely that the weight of the 5kW-Hr capacity version will equal that of the HKS-powered aircraft.”

Weights and performance numbers are based on currently available batteries, which are projected to improve with time. We look forward to seeing the new motor installation and Goshawk’s first flights.

*KEAS: knots equivalent air speed – calibrated airspeed corrected for atmospheric properties at the particular altitude.

{ 0 comments }