500 Miles on 10-Percent Plastic Waste

Plastic threatens to choke the world’s oceans, five gyres or “garbage patches” of plastic debris twirling around in toxic profusion.  These plastic bits and pieces, slowly photodegrading into smaller and smaller pieces, also choke the fish and birds that feed on or in the water.  It’s a huge problem that invites grand visions for solutions

In what may at first glance seem a very small attempt to help,”Campaigning Pilot Jeremy Rowsell has made history by flying a light aircraft more than 500 miles from Sydney to Melbourne, Australia, using conventional fuel blended with 10% fuel manufactured by the UK’s Plastic Energy, from plastic waste.”

Jeremy flies a Vans Aircraft RV-9A, which uses a blend of “end-of-life” plastic waste, transformed from a pollutant into a viable jet A1 fuel by a process developed by Cynar PLC, an Irish firm.  That process has been picked up by Plastic Energy SL, a Spanish company.

Jeremy Rowsell with RV-9A, powered by Wilksch three-cylinder diesel engine and fueled by 10-percent plastic waste

Jeremy Rowsell with RV-9A, powered by Wilksch three-cylinder diesel engine and fueled by 10-percent plastic waste

“On Wings of Waste” (OWOW) uses a “’10 per cent solution’ the ‘On Wings of Waste’ team’s campaign to inspire people to recycle plastic waste has taken four years to get off the ground,” according to OWOW’s press release.  We’ve reported on the effort since 2012.

The team promotes a four-stage proposition:

  • Recycle – Persuade the public to support recycling plastic waste.
  • Re-use – Transform plastic waste to a fuel that can be blended with Jet A1.
  • Re-fuel – Adopt a 10-percent blend of fuel derived from plastic waste.
  • Rescue – Slow down and eventually halt pollution of the world’s oceans.

Jeremy points up the stalwart nature of his effort.  “After years of preparation and many ups and downs we’ve finally shown that the eight million tonnes of plastic dumped into the oceans each year can be put to good use.  We blended 10 per cent of fuel manufactured by Plastic Energy with conventional fuel and the flight was a dream.”

Team mate Jo Ruxton, one of the producers of the film, “A Plastic Ocean,” adds, “Plastic breaks up into small particles, mixing with the plankton at the ocean surface. Plankton is at the heart of the food chain and provides us with more than half the oxygen we breathe – our oceans keep us alive  We can’t yet safely remove plastic particles from plankton that lives in the ocean, so we must stop dumping plastic waste in the ocean. There are estimated to be 5.25 trillion particles of plastic floating – mainly at the bottom – of the world’s seas.”

OWOW shows that although an RV-9A might not consume that much fuel, the long-term effects of a 10-percent solustion could be enormous.

Jeremy with fuel. 10-percent plastic fuel could be easily supported with existing infrastructure

Jeremy with fuel. 10-percent plastic fuel could be easily supported with existing infrastructure

“Jeremy’s flight could have a profound effect on the aviation industry. A 747 aircraft on a 10,000 mile flight burns 36,000 gallons of fuel and 33% per cent of airlines’ operating costs are spent on fuel. If 3,600 (UK) gallons of that fuel was sourced from plastic waste it would be the equivalent of 18 tonnes of waste plastic that might otherwise be dumped in the ocean. Factor in the 1200 flights a day that are made from Heathrow, and approximately 21,600 tons of waste plastic would be transformed from pollutant to fuel – every day.”

Plastic Energy converts end-of-life plastic to fuel, getting a 95-percent useable output, with the remaining five-percent “char” used in fuel additives and pigments.  There are no toxic emissions released into the environment, according to Plastic Energy.  Its President and CEO, Carlos Monreal, is happy with the exposure the 500-mile flight has provided for his company’s efforts.  “Jeremy’s flight is a tremendous opportunity to showcase how plastic waste can be put to productive use instead of thrown away to pollute the oceans or despoil the land. We are delighted to be supporting this adventure.”

World renowned Naturalist Sir David Attenborough has backed the OWOW project saying: “The Wings of Waste flight, I hope, will bring the attention of the world to this great solution that is there waiting to be taken if only we can get the support of people to do so.”

Do us and the planet a favor.  Pick up the next discarded plastic water bottle you see.  Recycle it.  Millions of us doing that might contribute to a solution, rather than a problem.

Thank you to Richard Peel, in charge of media for the UK, EU, and USA for OWOW, for the press release and photos.

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How Cheaply Can One Fly?

How low(cost) can you go and still fly?   That question forms one of the pursuits of the Minimalist Airplane Study Group, hosted by William Rich on Yahoo Groups.  He may have found an answer that leads to several intriguing alternative uses for the type of electric powerplant described below.  Use of model aircraft components leads to a low-cost build, and judicious use of off-the-shelf parts from other hobbies keeps costs low and speeds up the development process.

He points to a hack from Laserhacker.com, which uses a motor, controller, propeller batteries and connectors one might find at the local hobby shop.  This assemblage manages to fly a paramotor despite the small size of the motor and the relatively small size of the propeller.

The Laserhacker link shows not only several videos (this has to be the most fun per dollar flying machine), but includes the parts list and pricing for everything but the final battery pack.  Components include 3D-printed items from Thingiverse.com.

Weighing things out, this would be a remarkably light system.  Batteries, for instance, calculated from packs comparable to the listed Zippy’s, would be around 10 pounds.  The Turnigy Rotomax motor weighs 7.8 pounds and the Biela carbon fiber propeller a mere 0.6 pound.  Even with the backpack frame and “Carp Buster” prop ring and net (clever repurposing of off-the-shelf parts) the system should not be over 25 pounds.  This is less of a landing hazard and backache than the up-to-80 pounds of more powerful units.

Such innovations, starting with Csaba Lemak’s first flights with a powered paramotor in 2007, convinced your editor that lightweight electric flight was a practical and economic reality with rigid-wing machines. After all, Eric Raymond had flown across the United States in 2009 with his model-motor-powered Sunseeker, and others had demonstrated limited hops before that.  But the draggy nature of the powered parasail showed that excellent performance might be possible with the units pushing or pulling ultralight aircraft skyward.  Imagine a series of designs that use off-the-shelf model gear (including hybrids) to allow low-budget flying.

January 12 Followup

William Rich included the following in his Minimalist Airplane Study Group discussion yesterday.  It has a link that helps one understand the basic design needs for powered paragliders.

“The tentative requirements are safety, low cost, 5 to10-minutes duration, and 250-fpm minimum climb for a 175-pound pilot (skivvies). Lots of discussion but it all boils down to energy density, efficiency, and work required to achieve the requirements.
“The novelty is learning to love short electric flights to save money and minimize propulsion weight.
“Perhaps someone would be kind enough to set me straight (I fear our SUNNY pilot may weigh 130-pounds!).
“Here is a typical electric discussion thread (of the many) –

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While we wait (with increasing patience or impatience depending on our personalities) for the next round of battery developments to make pure electric airplanes a reality, hybrid possibilities abound.  The definition of “hybrid” might not be as coherent as those used for automobiles.  Some “hybrids in this entry allow extended letdowns following a primary engine failure.  In that case, the added electric motor/generator gives extra minutes to find a safe landing space.  While both motor and primary engine are operational, the system acts much like an automotive hybrid system, both motor and engine combining outputs for added power, or the electrical portion recharging batteries while the engine maintains cruise power.

Some are more like automotive serial systems, an engine-driven generator charging batteries which power the propulsion motor.  Pipistrel, though the Hypstair project, has a 200-kilowatt (268-horsepower) unit ready for test flights in 2017, according to Tine Tomazic, Director of Research and Development.

Several Flying Now

Several years ago, Flight Design in Germany attached a generator/motor setup to a Rotax engine.  The electrical add-on would assist in takeoffs, charge batteries while in flight, and take over as a primary power source if the gasoline engine failed.  This same hybrid approach applies to similar current systems.

Axter Aerospace

Mounted on a Tecnam P92, the Axter Rotax/electric motor combination allows up to 15 minutes of 40-horsepower flying if the Rotax fails.  That should be enough to find a landing area and make a safe letdown.  The Spanish company now markets the powerplant with a variable-pitch propeller.

Ashot Ashkelon

This Israeli system had a brief moment in the spotlight, but seems not to be included in the company’s lineup at this time.  Ashot Ashkelon manufactures many aerospace components, and their hybrid system is shown in coverage of their displays at the Le Bourget Air show in 2015.  The system is markedly similar to Axter’s.

E-Genius’s Hybrid System

e-Genius has been flying with its add-on pod for over a year now, and tests show predictions of 1,000 kilometer (620 mile) trips are doable.  The 20-kilowatt generator burns five liters per hour, and is turned on after e-Genius has gained sufficient altitude to make its added sound level imperceptible from the ground – a practice that seems perfect for a noise-conscious world.

Close to Flight

Equator’s Hybrid System

Both the Equator P2 and e-Genius rely on the Aixro/Engiro hybrid generator-motor system for flight.  Equator’s units include a 60 kilowatt-hour generator powered by an Aixro Wankel engine, and the motor at the propeller puts out 100 kilowatts (130 horsepower).  Thomas Brodreskift and his crew recently fired up the system and all looks well for its eventual flight tests.

Hypstair

As Tine Tomazic explains in an interview with AVWeb’s Paul Bertorelli, This most powerful of hybrid systems, destined to make the modified Panthera a high-performance hybrid.

Under Development

MDC’s Micro-Turboalternator

This micro-turboalternator drives a lightweight permanent magnet generator, which the makers claim consumes only one pound of fuel per hour per kilowatt output.  Its claimed power-to-weight ratio is “1.7 kilowatts per pound, six times the specific power, or 12-15 times the energy density of lithium polymer batteries.”  The design places the power turbine driving the bypass flow at the front of the combustor rather than at the engine exhaust.  A compact recuperator recovers heat from the exhaust decreases fuel consumption.

Given company figures, a 20-kilowatt microturboalternator would weigh under 12 pounds and consume 20 pounds (three gallons) of fuel per hour at full output.   This performance possibly led to the project garnering funding from DARPA and NASA.

DARPA Funds Liquid Piston

Using its High Efficiency Hybrid Cycle (HEHC), The Liquid Piston X Engine has few parts and three combustion events per rotor revolution, resulting in tremendous power density, according to its makers.  One of these coupled to a compact generator may prove useful for ultralight-type aircraft.  Whether fuel consumption becomes an issue remains to be seen at this point.

NASA’s Forays into Hybrid Power

In the video here, Mike Ricci, Vice President of Engineering at Launchpoint Technologies shows off a few of the company’s offerings.  As interviewer Lee Teschler, Executive Editor at Design World points out, Launchpoint is a NASA contractor, apparently involved with several recent projects.

Launchpoint’s portfolio shows extremely light generator sets, using off-the-shelf components from the model aircraft industry as starting points.  With the redundancy inherent in hybrids, less-expensive components could prove to be viable and at least nominally reliable.  Used in pairs or greater numbers, they could be a low-cost answer for light aircraft such as ultralights, self-launching sailplanes or motorgliders.

Promise for Near-term Solutions

Hybrid systems are a possible answer for near-term solutions to making aviation cleaner, if not totally pollution free.  Many entries and their combinations at all power levels make tempting excursions into researching these possibilities an exciting challenge.  We’ll have examples in new entries soon.

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If Santa Lived in a Soho Loft and Built Drones

There is much happening in electric aviation, including this flying Santa Claus, dangling from what is claimed to be the world’s largest homemade drone.

And in this interesting behind-the-scenes video we find that Casey Neitstat either has arms of steel, or a clever harness maker who probably outfits touring companies for Peter Pan stage presentations.  The 16-motor system seems capable of hauling a fairly large human skyward, but some critics think this is a sham of some sort.  Your editor sides with the theory that this is a real drone, since Samsung has seen fit to link its name to the project (and the video evidence seems fairly convincing).  In the interests of full disclosure, though, Casey has pulled some fakery in previous stunts, so take this all with several grains of salt, just in case.

If this isn’t enough Casey and Santa-dragging drones for you, try on the VR headset you got for Christmas and indulge in the full 360-degree treatment.

Casey claims to have given up Vlogging (video logging), but his web site lists four ways to access the fruits of his ever-excited imagination: two YouTube channels, Facebook, Twitter, Beme (the app he sold to CNN), and Instagram.  Like Santa, he is everywhere.

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Flying (Quietly) Like a REAL Bird!

Not Just an Academic Exercise

Justin Jaworski, Lehigh University assistant professor in the Department of Mechanical Engineering and Mechanics, P.C. Rossin College of Engineering and Applied Science, writes, “From antiquity to Harry Potter, owls continue to captivate and mystify us. Perhaps owls’ most mysterious feat is their ability to fly silently, which enables them to both sneak up on prey and hunt on the wing using their ears alone. For over 80 years, silent owl flight has been linked to a set of unique plumage features, but only recently have the mechanisms to suppress the ‘swoosh’ noise from owl wings been addressed in earnest.”

Justin Jaworski with an object of his studies

Justin Jaworski with an object of his studies

This suppression of noise ensures that prey hunted by owls never know what hits them.  The doves that frequent your editor’s deck, for instance, have no such noise-limiting features, and make quite a racket when the door opens for their morning feeding.  Likewise, a pair of Mallard Ducks who’ve decided to blend in with the small songbirds are audible swooping in from over 50 feet away.

Jaworski has made detailed comparisons of the noise levels generated by different birds, and then gone to microscopic detail to analyze how owls achieve their stealthy flight.  Such findings may make neighborhood airports better neighbors, or reduce the number of noise claims by people living near wind turbines.  Researchers explain that finding might apply to reducing “noise created by air seeping through automobile door and window spaces.”

Jaworski notes that many species of owls suppress their noise at sound frequencies about 1.6 kilohertz (kHz) – above the range that can be heard by most humans.  Because of their great success in picking off small rodents and even rabbits, owls must be taking advantage of that quiet approach.

Three key elements of the owl's quiet wing: a serrated leading edge, a downy canopy across the upper surface feathers, and a fringed trailing edge

Three key elements of the owl’s quiet wing: a serrated leading edge, a downy canopy across the upper surface feathers, and a fringed trailing edge

The owl’s wing includes a serrated leading edge, a “canopy” of downy feathers that overlap and direct airflow across the wing’s chord, and a soft fringe along the trailing edge.  Recreating a “velvety” down canopy on a production aircraft wing could be a tough project, Jaworski and his fellow researchers came up with a 3D-printed trailing edge consisting of “finlets.”  After having tried a variety of open-mesh cloths – including wedding veils – the team found that the threads cross-wise to the airflow did not contribute materially to noise reduction.  They created a series of parallel fibers that direct the air across the wing and off the trailing edge and that emulate the sound-deadening effect of the owl’s wing.  The 3D-printed trailing edge can be fitted to existing wings – giving a 10dB reduction sound without harming overall performance.

Streamwise-oriented 'finlets' are installed on a wing or blade trailing-edge to reduce trailing-edge noise by up to 10dB without substantial changes to the aerodynamic performance and over a range of angles of attack. Photo: Nathan Alexander

Streamwise-oriented ‘finlets’ are installed on a wing or blade trailing-edge to reduce trailing-edge noise by up to 10dB without substantial changes to the aerodynamic performance and over a range of angles of attack. Photo: Nathan Alexander

These noise-reducing effects have been known since at least 1932 and documented in 1972 and 1974 papers.  Jaworski and fellow researchers from four universities contributed to two papers, “Bio-inspired trailing edge noise control” in the American Institute of Aeronautics and Astronautics Journal and “Bio-inspired canopies for the reduction of roughness noise” in the Journal of Sound and Vibration.  These efforts not only include more precise measurements than earlier efforts, but led to a practical product for real-world applications.

Siemens’ Owl-like Feathers

Siemens has a totally practical intent for their trailing edge treatment of wind turbine blades.  The company called their owl-like appendage “DinoTail,” soon to be in serial production according to the company.  Siemens credits the need for near-silent operation of wind turbines to make them acceptable for on-shore operation.  Improved aeroacoustic performance should allow wind turbines greater latitude in placement around otherwise off-limits population centers.  The technology can also allow pulling greater production without increasing noise.

Vortex generators on the forward part of the blade, combined with a “combination of serrations and combs” on the trailing edge of each blade, “creates fine vortices at the point where the fast air stream from above the blade profile meets the slower flow from below. As a result, the aerodynamic noise from the trailing edge of the blade is reduced significantly.”

Siemens DinoTail, a bit coarser than Jaworski's trailing edge, but designed for large-scale turbine blades

Siemens DinoTail, a bit coarser than Jaworski’s trailing edge, but designed for large-scale turbine blades

At the Wind Energy Hamburg 2016 trade show, Stefan Oerlemans, Key Expert in Aeroacoustics with Siemens Wind Power, explained, “This structure that was inspired by owl wings does not compromise the aerodynamic performance.”  Since the combed teeth are a second generation of the original DinoTail add-ons, they will replace the original items on onshore wind turbines, and on future new models.

A high level of biomimicry seems like a good way to advance aeronautics and efficient capture of wind energy.  The birds, especially wise old owls, have been doing it right all along.

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EC04 Design Wins 2016 Berblinger Prize

A Big Win for Stuttgart Team

Dipl-Ing Ingmar Geiß, Deputy Project Leader for e-Genius at the Institute of Aircraft Design at the University of Stuttgart, shared this pleasant news:  “I am happy to tell you that our hybrid-electric “ECO4” has won the Berblinger Prize 2016.  ECO4 combines an optimized electric airframe with a modern combustion engine generating electricity. This combination leads to an aircraft which cruises at 120 knots and consumes 40 percent less fuel than comparable state-of-the-art airplanes with conventional propulsion. As a further advantage, a small but powerful battery system enables a silent take-off without the combustion engine running, reducing significantly the noise emissions.”

EC04's configuration is similar to that of Icare, e-Genius

EC04’s configuration is similar to that of Icare, e-Genius

The Berblinger Prize

Gunter Czisch, mayor of Ulm, presented the 23,000 euro ($24,035 US) prize to the team, which intends to invest the amount “directly into the further development of the airplane.”  The prize was founded in recognition of Albrecht Ludwig Berblinger, “the little tailor of Ulm, who tried to cross the river Danube in 1811 with a glider.  Although capable of flying, his glider crashed due to severe turbulence.  A jury of 16 members from aerospace industry, universities, research institutions and representatives of the town of Ulm decide the winner.

Stuttgart team with Berblinger Prize. Ingmar Geiss is front row left

Stuttgart team with Berblinger Prize. Ingmar Geiss is front row left

A Masterful Design

Part of Ingmar’s Master’s Degree program, EC04 represents an expansion of his earlier work with e-Genius, the two-seat, battery-powered craft that won second place in the 2011 Green Flight Challenge.  e-Genius has since been flown by Klaus Ohlmann to set several records and undertake long cross-country flights.  Extending that range, a new pod holding a Wankel engine and generator allows flight up to 620 miles, well beyond the comfort range of most pilots.

EC04 will increase the range to 1,200 nautical miles – with four persons on board (1,800 miles with three up).  EC04 will have a quiet takeoff distance of 600 meters (1,968 feet) and a climb rate of five meters per second (984 feet per minute).  Considering its 45-kilowatt (60 horsepower) Diesel-powered generator, predicted performance is remarkably similar to that of a 180-horsepower Cessna SkyhawkA Cessna 172M at 75-percent power, cruising at 8,000 feet, will burn through its 38 gallons of useable fuel in 4.7 hours, according to the Cessna 172 Guide.  That’s a fuel burn of 8 U. S. gallons per hour.

EC04 has tricycle gear, easy entry to what looks to be a roomy cabin

EC04 has tricycle gear, easy entry to what looks to be a roomy cabin

The EC04 would supposedly represent a 40-percent savings, making its equivalent fuel burn 4.8 gallons per hour, for an economy of 28.75 mpg, or 115 passenger miles per gallon.  Your editor will be happy to be corrected or updated on these back-of-envelope figures, since these seem low compared to what the HY4 and e-Genius manage.

A Strong History

EC04 continues the long-term work of Professor Rudolf Voit-Nitschmann, who developed the motor on vertical stabilizer configuration with Icare 2, a solar-powered craft that first flew in 1996.  E-Genius continued with this configuration.  At the 2011 Green Flight Challenge, the Professor explained to your editor that the propeller’s placement allowed low drag, its blast impinging only on the upper part of the stabilizer and rudder.  E-Genius has proven itself for the last five years with increasingly long flights, the latest powered by a hybrid system similar to that proposed for EC04.

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Compressed natural gas (CNG) has several things going for it.  It is cheaper than gasoline or diesel fuel, has lower emissions, and for a conventional piston-engined airplane, is the equivalent of over 130 octane, far more powerful than 100-octane low lead (100LL) and cleaner burning.

CNG Fuels in England

CNG filling stations are growing across the country as fleet owners take advantage of the economics of converting their vehicles, but are still few and far between in the west, with the exception of California.  There are under 900 stations throughout America.  Alluring as CNG might be for drivers, pilots used to paying $5.50 per gallon for avgas should be charmed by CNG’s price of $1.00 per gallon equivalent.

That is with conventional, fossil-based CNG, basically a storable version of natural gas.  That leads to its less-desirable characteristics.  First, it pollutes, too, and is a source of greenhouse gases.  Second, natural gas has a hard time overcoming its association with fracking, or hydraulic fracturing – the injection of water, chemicals and sand into rock that contains natural gas.  This forces gas from the fractured seams for collection.  But it also leaves the underlying shale or rock formation weakened – possibly leading to earthquakes.  Oklahoma, which has a disproportionate number of CNG distribution stations, also has a recent uptick in temblors.  Beyond that, groundwater pollution is often associated with fracking and natural gas extraction.

Biomethane can be readily added to pipeline supplying CNG's pumps throughout England

Biomethane can be readily added to pipeline supplying CNG’s pumps throughout England

A non-fossil version of CNG would seem desirable.  GNG Fuels in England is working on that, along with a distribution network that takes advantage of existing supply lines.  Claiming to be the UK’s leading supplier of CNG, GNG Fuels now sources its entire production from biomethane.  The company explains, “The biomethane is made from the gas harvested through the processing of waste generated by food production, which is then injected directly into gas pipelines. The gas is subsequently compressed at CNG Fuels’ own high-capacity refueling stations in Leyland (Lancashire) and Crewe (Cheshire).”

We’ve discussed liquid jet fuels made from municipal and farm waste in recent entries, and both United and Alaska Airlines have made flights fueled partly with non-fossil materials even forest slash debris.

Economics and Environment

United Kingdom-based CNG Fuels purveys a renewable biomethane fuel, which they claim to be ”The most cost-effective and lowest-carbon alternative to diesel for heavy goods vehicles (HGVs). The fuel is 35%-40% cheaper than diesel, and emits 70% less CO2 on a well-to-wheel basis. It therefore offers fleet operators the chance to significantly reduce running costs and emissions.”  Several British trucking firms have committed to using the new biomethane fuel for their long-distance haulers.

CNG reports, “The biomethane is independently verified as renewable and sustainable, and approved under the Department for Transport’s Renewable Transport Fuel Obligation (RTFO) scheme.”

At 65 p (pence or $0.83 US) per kilogram, bio-CNG is equivalent to paying 49p per liter ($0.62/liter, or $2.35/gallon US) for diesel.  Compare this to current prices for “diesel petrol,” currently at 117 p per liter ($1.25), or the equivalent of $.84 per U. S. gallon.  This low price is without government subsidies, making the economics even more attractive.  Apparently, the biomethane, made in waste treatment facilities that break down organic matter, is “not supported by the Renewable Heat Incentive or other subsidy schemes.”

Distribution and Economics

England is small enough, and with an established high-pressure gas grid, that adding a network of refueling stations is reasonable and economically feasible for CNG.  Whether operators will find the economics reasonable is another question.  GNG “is targeting operators of high-mileage HGVs, who stand to make the biggest financial savings and carbon impact. Its customers’ vehicles travel an average of 125,000 miles every year, and CNG-powered trucks are more expensive than those that use diesel.

”However, for HGVs covering this mileage, fuel savings can recoup the extra cost within around two to three years. Furthermore, CNG fuel-powered engines meet the latest Euro 6 emissions standards, and are up to 50% quieter than diesel engines.”

Ford has sold a good many CNG/propane vehicles over the past decade, with sales growing annually.  After paying for a $315 factory prep, a customer can take his large pickup to a “Ford Qualified Vehicle Modifier,” who will install the dual-fuel package for $7,500 to $13,000.  Most who own big-rig pickups in commercial operations put enough miles on to justify the conversion costs.

That price differential for storing compressed gas led to Honda’s attempt at a Civic using LNG/CNG to disappear quietly from the market.  Its higher initial cost, indifferent performance, and lower fuel economy did not endear it to consumers.

Natural Gas Airplanes?

Russia’s Tupolev works attempted a hydrogen-powered airliner, the TU-155, in 1988, converted it to natural gas, but dropped the project with the fall of the Soviet Union.

TU-155 went away with Soviet Union

TU-155 went away with Soviet Union

 

Aviat’s Dual-Fuel CNG Demonstrator

Seen at Oshkosh in 2014 outside the Innovation Pavilion, Aviat’s Husky with a large bulge underneath was flown on both 100 low-lead (LL) aviation gasoline and compressed natural gas.  In a recent call to Bill Sullivan, he explained that the airplane had been an “engineering challenge,” but has not been offered for sale since its public display.  He’s flown it on 100LL, and noted that CNG offered the equivalent of 130 octane.  An engine would need higher-compression pistons and other modifications to take full advantage of the added potential of the fuel.  The lack of lead in CNG might also produce great wear in the engine, that “LL” feature in aviation gas necessary for extending engine life.

Questioned about the bulky fuel container, Sullivan explained that was a first-generation tank, and that later improvements had condensed that bulk considerably.  We’re on the fifth generation currently.  Range would be limited to what could be done on that single tank, since other airports in the region might not have GNG available.  An entirely new infrastructure would be required to allow anything other than training flights mostly kept close to the departure airport.  In this respect, CNG trainers would be restricted much like Pipistrel’s Alpha Electro trainer (until better batteries become available).

What to Do?

If GNG can be made even cleaner by adding or substituting biomethane, several advantages accrue, including fewer emissions from the vehicle and less methane being released into the atmosphere from rotting plant matter.  The fuel can be less expensive, but the necessity of modifying the vehicle to take advantage of that can be off-setting.  This may be more easily accomplished in a compact, heavily agricultural land such as England, but harder to pull off in the far-flung reaches of America.

As gas prices rise again (predicted to top $3.00 a gallon again early in 2017), fleet owners and airline magnates will look at economical solutions more favorably.  Given changes in the political infrastructure, we might be surprised at the next turn in our ongoing story.

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SolarStratos Unveils a High-flying Motorglider

Raphael Domjan is an adventurer in every sense of the word.  He’s sailed around the world on solar power, and attempted to paddle his way across the Northwest Passage in a solar-powered kayak. And now, he’s revealed an airplane that could carry him to the stratosphere on solar power.

SolarStratos is a 24.9-meter (81.7 feet) span motorglider shown to the public for the first time yesterday in Payerne, Switzerland.  With stage smoke and rock-concert lighting glittering from the solar cells on its wings and tail, the Calin Gologan-designed craft materialized before the crowd of 400 (according to Calin) gathered in the specially-built hangar.

Raphael Domjan’s stratospheric solar plane was unveiled December 7 in Payerne, Switzerland, to 300 guests, including ambassadors, partners, government representatives and the world’s media. Photograph courtesy of SolarStratos

Raphael Domjan’s stratospheric solar plane was unveiled December 7 in Payerne, Switzerland, to 300 guests, including ambassadors, partners, government representatives and the world’s media. Photograph courtesy of SolarStratos

At a loaded weight of only 450 kilograms (990 pounds), SolarStratos should climb well on its dual motor, a mere 19 pounds itself.  A planned flight time of approximately five hours to take pilot and passenger to the planned 75,000 foot, near-space experience.  On only 42.8 horsepower swinging a 2.2-meter (7.2-feet), four-bladed propeller, this is, outside of the Perlan Project’s sailplane or high-altitude balloons, perhaps the lowest power of any record altitude attempt.

Where Perlan uses a pressurized cabin to protect its occupants and permit them to (we hope) breathe easily, SolarStratos has an unpressurized cabin, but with elbow room to allow movement even with occupants in bulky pressure suits.

Calin further explained that “Our two companies, PC-Aero GmbH (Manned applications) and Elektra-UAS GmbH (autonomous and remotely-piloted flight) merged in Elektra Solar GmbH which is now officially a spinoff from DLR ( German Aerosoace Center), Institute of Robotics and Mechatronics.”

The combination of high adventure and high technology has led to a beautiful aircraft with an ambitious flight plan.  We wish them the greatest of fortunes.

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A New Twist on Retractable Motors

GP Sailplanes in Poland recently partnered with MGM Compro of the Czech Republic to add electric power to its line of small, sleek sailplanes.  Concentrating initially on the 13.5 meter racing class (44.29 feet), GP’s craft provide high performance with light weight and compact dimensions.

A Long Reach on the Antares

Putting a retractable motor and folding propeller into such a tight space required some clever engineering.  Think of the tall mast on the Lange Antares or the Arcus two-seater.  These are large, heavier machines, so the propeller, mast and motor can be accommodated (tightly) in their fuselage.  The video gives a good view of just how close the quarters are on the Antares at about the 3:14 mark.  With a 118-square-foot wing area and 59-foot wing span (the 18T model), the average chord of the Antares is two feet.

Tucking the Motor into a Tighter Space

GP’s aircraft are much smaller, with narrow chord wings, part of their high aspect ratios.  That gives a smaller center of gravity range.  RecreationalFlying.com suggests not exceeding a CG range of 20 percent – less than eight inches on a typical trainer.  For the Antares, that range is less than five inches.  The GP14 SE has a mean aerodynamic chord of about 20 inches, so the CG range is closer to four inches.  Constrained by a need to keep CG travel to a minimum, the designers came up with an ingenious solution, something they label RESLS – retractable electric self launching system.

A Lightweight, Compact Package

Weighing only 374 pounds (170 kilograms) empty and 924 pounds at maximum takeoff weight, the GP14 should perform well with its 25 kilowatt (34.5 horsepower) Rotex motor.  The four kilowatt-hour Sony Li-ion battery pack is 44 pounds of the empty weight, and it’s possible to add four kW-hr or two kW-hr packs to extend endurance.  Since these fit in the wings, the center of gravity is not affected.  Wide-body pilots can fit into the standard fuselage, but those lucky enough to be of lower heft can have a slim fuselage option, making the plane perform even better.

Thanks to Martin Dvorsky of MGM Compro for alerting your editor to this news.

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5X Lithium Sulfur Battery with a Gut Feeling

Bio-mimicry presents itself in aerodynamics, from the emulation of soaring bird’s wing shapes on sailplane’s surfaces to owl-feather-like trailing edges on wind turbines.  We don’t often think of biological equivalents in energy storage (your editor didn’t until now, at least).  But researchers at Cambridge University in England and the Beijing Institute of Technology in China have turned to the small intestine for their breakthrough in battery development.

Tiny cells lining the human intestine inspired these researchers to develop a prototype of a lithium-sulfur battery that they claim could have five times the energy density of conventional lithium-ion batteries.  Dr. Paul Coxon from Cambridge’s Department of Materials Science and Metallurgy says “This gets us a long way through the bottleneck which is preventing the development of better batteries.”

Is That You, Villi?

Structure of villi in the small intestine

Structure of villi in the small intestine

Villi in the gut help process food being digested, trapping nutrient particles in millions of tiny, “finger-like protrusions” which increase the absorbent surface area over which digestion takes place.  In batteries, surface area enables greater electrochemical reaction between anodes, cathodes and electrolytes.

Dr. Vasant Kumar and his Cambridge team created and tested a lightweight nanostructured material with tiny zinc-oxide wires, which they placed on the battery’s electrodes.  According to researchers, “This can trap fragments of the active material when they break off, keeping them electrochemically accessible and allowing the material to be reused.”  This prevents loss of active materials and increases the life span of the battery.

How This Works in a Lithium-Sulfur Battery

A typical lithium-ion battery is made of three separate components: an anode (negative electrode), a cathode (positive electrode) and an electrolyte in the middle. The most common materials for the anode and cathode are graphite and lithium cobalt oxide respectively, which both have layered structures. Positively-charged lithium ions move back and forth from the cathode, through the electrolyte and into the anode. Illustration: Futurism.com

A typical lithium-ion battery is made of three separate components: an anode (negative electrode), a cathode (positive electrode) and an electrolyte in the middle. The most common materials for the anode and cathode are graphite and lithium cobalt oxide respectively, which both have layered structures. Positively-charged lithium ions move back and forth from the cathode, through the electrolyte and into the anode. Illustration: Futurism.com

Different materials determine how much energy can be squeezed into the battery.  Carbon electrodes can take on six lithium ions per carbon atom.  Sulfur can take on many more, making the battery theoretically more energy dense.  At least five times more so, if we’re to believe the Cambridge/Beijing researchers.  That’s where there the electronic villi come into action.

Mimicking Our Inner Workings

During discharge, when we get the stored energy back as work, “The lithium and sulfur interact and the ring-like sulfur molecules transform into chain-like structures, known as a polysulfides. As the battery undergoes several charge-discharge cycles, bits of the polysulfide can go into the electrolyte, so that over time the battery gradually loses active material.”

To emulate the work villi do in the body, researchers “Have created a functional layer which lies on top of the cathode and fixes the active material to a conductive framework so the active material can be reused. The layer is made up of tiny, one-dimensional zinc oxide nanowires grown on a scaffold. The concept was trialled using commercially-available nickel foam for support. After successful results, the foam was replaced by a lightweight carbon fiber mat to reduce the battery’s overall weight.”

Study co-author Dr. Yingjun Liu explained, “Changing from stiff nickel foam to flexible carbon fiber mat makes the layer mimic the way small intestine works even further.”The high surface area exposed on the fingers and its strong chemical bond with the polysulfides allows the material to last longer, and increases the lifespan of the battery.

“This is the first time a chemically functional layer with a well-organised nano-architecture has been proposed to trap and reuse the dissolved active materials during battery charging and discharging,” said the study’s lead author Teng Zhao, a PhD student from the Department of Materials Science & Metallurgy. “By taking our inspiration from the natural world, we were able to come up with a solution that we hope will accelerate the development of next-generation batteries.”

Not So Fast

Alas, as with so many such developments, things done at laboratory scale sometimes take another decade to reach commercial reality.  Talk of Manhattan Project levels of investment and urgency never seem to gain ascendancy for peace-time endeavors.  Let’s hope this and similar efforts find willing investors.

See the researchers’ results in the October 26, 2016 edition of Advanced Functional Materials

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