Comco Ikarus Flies on Electric Power

Relatively unknown to American pilots, Germany’s largest ultralight aircraft manufacturer, Comco Ikarus in Mengen, was able to announce the first flight of its successful two- seater C42 / CS as an electric version just before the start of AERO, the annual aircraft exposition in Friedrichshafen.

Geiger-powered version of Comco Ikarus C42 CS as shown at Aero Expo in Friedrichshafen, Germany

Comco’s C42 CS forms the basis for the electric version.  The avgas-powered version flies with either an 80-horsepower or 100-horsepower Rotax engine, the electric version with a 32-kilowatt (50 horsepower) electric motor from Geiger Engineering.  Geiger’s power package includes their dedicated controller, control lever, and monitoring instrument.  Four battery packs, 15 kilograms (33 pounds) each, power the prototype, but production versions will have six packs, enabling flight times of up to 90 minutes.

Geiger makes a full array of motor, controller, and battery packages available

The first electric flight was completed by Comco Ikarus’ managing director Horst Lieb on April 15, 2018.  Comco notes, “The complete electrical unit with batteries is only marginally more expensive than the combustion version.”

The aircraft, with a span of 8.71 meters (28.6 feet) and an empty weight of 280.5 kilograms (617.1 pounds), is small and lighter than most Light Sport Aircraft (LSAs), and can carry a 192 kilogram (422.4 pound) payload in its Rotax powered version.  The manufacturer explains the airframe had to be modified for electrification but does not list specifications for the battery-powered prototype.  Battery weight with four packs will be 132 pounds, 30 pounds more than the 17-gallons (102 pounds) of fuel carried in the Rotax machines.  Performance on the 50 electrical horsepower will doubtless be less sprightly than for even the 80-horsepower gas edition.

For those concerned that the machine’s light weight might indicate a certain fragility, consider this video your editor chanced upon, showing a C42 pilot chasing a wing-suit flyer down a perilous mountain slope.  Kids, don’t try this at home!  (Or is this a wee bit of digital trickery?)

Canadian and American sales are handled by the Canadian distributor in Ontario, and it will probably be a while before the electric ultralight/LSA becomes available.  If electric prices stay close to those for the LSA models (below $65,000 US) the airplane might be a popular favorite.  After all, over 1,400 have been sold in Europe, making it one of the most popular light aircraft on the continent.

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Sun Flyer Takes to the Air

Following assorted powerplant and taxi texts, the prototype Sun Flyer 2 prototype took to the air over Centennial Airport (KAPA) south of Denver, Colorado.  Further tests will expand speed, altitude, and endurance capabilities, according to Bye Aerospace.

George Bye, Founder and CEO of Bye Aerospace, enthused, “We are excited about the future and the potential the Sun Flyer family of aircraft has to revolutionize general aviation, providing improved affordability and accessibility.  Lower operating costs are key to solving the student pilot drop-out rate, which is curtailing the successful attainment of badly needed airline pilots. The Sun Flyer 2’s $3 hourly operating costs are 10 times lower than traditional piston-engine flight trainers, with no carbon emissions and significantly reduced noise.”

Such economies have probably contributed to the 121 reservations for Sun Flyers by organizations such as Spartan College of Aeronautics and Technology, where students might be able to avoid taking out loans to obtain their licenses and ratings.  According to Aviation Week, George claims, “Flight schools desperately need this aircraft,” a step into the future from current hard-working trainers.  Those who’ve grumbled about the lack of shoulder room in current side-by-side machines will find relief in Sun Flyer’s 46-inch wide cabin, which can accommodate two 220-pounders.  Occupants will face an Avidyne glass panel, and can avoid fateful smacks on the ground with the full-airplane ballistic recovery parachute.

featuring a best climb rate of 1,150 fpm; normal speed range of 55-120 kt.; maximum endurance of 3.5 flight hours; super-recharge time of 30 minutes; zero emissions and nearly silent operation, as reported by Aviation Week, Sun Flyer will have a lot to offer students and operators.

With only one moving part in the motor, maintenance will be “minimal,” and Bye estimates operating costs at about $14 per hour.

Batteries are not as efficient at producing the energy per pound that gasoline or Diesel fuels manage, but the LG Chem “MJ1” lithium-ion cells installed in the Sun Flyer are capable of 260 Watt-hours per kilogram.   EPS, Electric Power Systems, is contracted with Bye Aerospace to provide a complete energy package on Sun Flyers – both the two-seat 2 and four-seat 4, which will be brought to market soon.  EPS will supply battery modules (packs), battery management units and power distribution units.

Nathan Milleam, Chief Executive Officer for EPS, says, “This partnership aligns with our shared vision to advance all-electric aircraft for commercial aviation applications.  Our Energy Storage System leverages technology developed for NASA’s X57 platform, that enables our Battery Module to meet stringent FAA safety requirements around containment of cells in thermal runaway at a very light weight.”

Charlie Johnson, Bye Aerospace President, “extremely pleased to launch the test flight phase for the Sun Flyer 2 program,” hailed the “fantastic first flight.”  Bye Aerospace notes the Sun Flyer family of aircraft, including the Sun Flyer 2 and the 4-seat Sun Flyer 4 will be the first FAA-certified, U.S.-sponsored, practical, all-electric airplanes to serve the flight training and general aviation markets.

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The Coming Golden Age of Electric Air Races?

An Electric Great Air Race

100 years ago, a great air race – “The Great Air Race” – in fact, was held with competitors flying from Great Britain to the Northern Territories of Australia.  Crews had 30 days to make the trip, and considering the reliability of engines at that time and the primitive nature of aerial navigation, very little time to relax.

Of the six teams that entered, only two made it, three crashing (two fatally) and a fourth team being imprisoned in Yugoslavia as suspected Bolsheviks.  Only two teams finished, and only one received the 10,000 Pound Sterling prize (about 544,577 pounds today – over $775,000), enough to cause the six crews to accept the high risk  involved.

Captain Ross Smith with 10,000-pound prize money – equal to over a half-million today

The winning flight, in a Vickers Vimy WWI bomber, inspired the founders of Quantas to begin regular airline service in the country, with that company, nearly a century later, able to offer transit from Los Angeles to Sydney for under $1,500 (under $100 in 1919 currency).  They have just added non-stop flights from Europe to Australia with Quantas’ great reliability and safety – a far cry from the derring-do of 1919.

“On the morning of November 12 1919, pilots Ross and Keith Smith, along with mechanics Sergeants Wally Shiers and Jim Bennett, took off in their Vickers Vimy G-EAOU from Hounslow aerodrome in West London.

“Over the next 29 days they passed through countries including France, Italy, Greece, Egypt, Iran, Pakistan, India, Myanmar, Singapore and Indonesia before touching down at Fannie Bay, Northern Territory.

“The realization that it was possible to fly from Australia to Great Britain was part of the inspiration that spurred the founding of Qantas, by Paul McGinness and Hudson Fysh, in 1920.”

Richard Glassock, a fellow at Nottingham University, emailed to report on plans to recreate the 1919 race and  even a better-equipped 1934 air race from England to Australia, the MacRobertson Trophy Air Race.

Richard thinks the use of fuel-cell-energized, electric, all composite craft noted in contest rules will be the kind of technological leap that took place in the 15 years between the Great Air Race and the MacRobertson.

His interest in the projected event is echoed by University of NSW Emeritus Professor of physics John Storey, who said the race would help spur innovation in battery technology.

“The heart of the problem is to store enough energy in the batteries without making the aircraft weigh like an elephant,” Professor Storey said.

“The event is technically feasible, but being able to complete the route within 30 days is by no means a foregone conclusion.

“That makes 2019 the right time to stage it: in 2009 it would have been impossible, in 2029 it will be routine. It’s a very happy coincidence.”

An overview of the new and electric Great Air Race can be found here

According to Flight Safety Australia, “The 2019 race  is sponsored by the Northern Territory government, which has adopted a suggestion made by entrepreneur Dick Smith that the centenary of the original race be marked by a similar race for electric aircraft.

The 2019 race will be for three categories of aircraft:

  • Battery electric, which must use batteries, wind turbines or solar power to turn an electric motor.
  • Hydrogen fuel-cell electric, which must use the above methods and hydrogen.
  • Hybrid combustion-engine electric, which must be series hybrid, without any direct drive between the fossil fuel engine and the propeller or propulsion turbine.

Aircraft can be fixed wing, rotorcraft or lighter than air.

 

Middle East Short Course Racing

Some will wonder about the range required for even the shortest legs of the Great Air Race.  Organizers in Dubai are betting their Air Race E contestants will be able to stay in the air long enough for their eight laps around a five-kilometer (3.1 mile) course marked out by pylons, emulating Formula 1 air races seen at Reno, Nevada.

Air Race E course emulates that of Formula 1 racing

Even with throttles to the firewall, competitors should manage the 24.8 mile course, the G-forces of the turns putting a greater strain on pilots than on the motors or batteries.  Conversions of exiting Formula 1 racers or new designs meant to optimize things for electric power should provide plenty of thrills for spectators as the aircraft buzz by, eight at a time.

Less eclectic than the Great Air Race, Air Race E contenders will be limited to electric, battery-powered, propeller-driven craft of a certain weight and size.

Across the Pacific, Electrically

Another event will capitalize on unpiloted craft to make the 4,500 mile jump from Japan to California non-stop.  One competitor has accepted the challenge presented by iRobotics of Tokyo.  Their audacious idea, to fly from Tokyo to San Francisco, seems like something that would challenge most large commercial aircraft using the best generally-accepted technology of our day.  To add that the airplane will be unpiloted and powered by electricity adds a level of difficulty that makes this seem almost ludicrous.

Even iRobotics, in a Red Bull-sponsored web page, sees the almost implausible nature of their dare to others.

iRobotics trans-Pacific drone challenger

“A Japanese drone start-up is throwing out a challenge to all comers for a drone race from Tokyo to San Francisco. It sounds far-fetched, but a lot indicates that the race could happen much sooner than you think. Even if drones taking part will need AI, flight-control software, sensors and batteries that hardly exist today.”

Sabrewings Draco-2, a competitor for the trans-Pacific Drone Race

So far, they have one challenger, Sabrewings Aircraft, headed by Ed De Reyes.  A test pilot, a flight test engineer, and an FAA liaison for small and large companies alike, on various programs and projects. Ed is the Chief Executive Officer and co-founder of Sabrewing.

Both the iRobotics machine and the Sabrewing Draco-2 UAS are reputed to be capable of the 4,500 mile trip, and will feature dazzling arrays of technology and clever design.  For the Draco-2, Sabrewing lists the following:

“The DRACO-2 is designed to fly non-stop and un-refueled for 4,500 nautical miles (8,800 kilometers). It launches from a standard runway, and provides near-real-time video from on-board the air vehicle for the first 150 miles of flight. At cruise altitude, it then switches to high-resolution, low-light, on-board cameras that are updated every 5 seconds and provide a view of the aircraft path and the air vehicle’s location over land or water. Day or night, good weather or bad, the Rapier has the capability of flying for days without stopping or refueling.

“For added safety, the DRACO-2 has a unique, proprietary sense-and-avoid sensor suite that detects objects that may conflict with the air vehicle’s flight path – and can instantly turn right or left, climb or descend – to autonomously avoid anything in its way…even as small as a bird. The DRACO-2 can even fly safely on two rotors – and every essential system on board is redundant to assure mission completion.

“The DRACO-2 is controlled via satellite, and is in constant communication with both the Launch and Recover Element (“LRE” – located at the launch point in Japan) and Mission Control Element (“MCE” – located at the destination landing point of Moffett Field, Mountain View, California, USA). The air vehicle is monitored by two pilots on the ground, in constant contact with Air Traffic Control. The trip is expected to last about 45 hours – and provide spectacular views of the air vehicle and its flight path – both day and night – while in flight.

“The entire flight – from takeoff, climb, cruise and landing – will be available on the Pacific Drone Challenge website.

iRobotics, in tendering its challenge, is fearless in taking on all challengers.  They explain, “It might initially sounds strange, but iRobotics are hoping that giants like Boeing, Airbus, Google and many others will rise to the challenge. The Japanese start-up is not afraid of taking on companies that are easily 1,000 times bigger than them.

“It’s a gamble, of course. However, we feel that the race is a unique proposition that can help develop drones. We are pushing technology, making it capable of solving some of the challenges the human race faces. At the same time, it’s no secret that we’re hoping to make a profit, which I don’t think is wrong. It’s a situation where we’re having fun working on something we’re passionate about, which we believe will have a positive impact on the world, while challenging the idea of what can and can’t be done. It’s pretty much a perfect recipe,” Yoshiyasu Ando (CEO of iRobotics) says.

With three major electric air races with different goals, we might see a new golden age of (electric) air racing in the next few years.  Racing does improve the breed, as great car makers have long known.

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Pipistrel Alpha Electros Come to California

News from Joseph Oldham, founder of the Sustainable Aviation Project, and Michael Coates, United States master distributor for Pipistrel Aircraft, heralds the largest delivery of electric training aircraft to date.  Four Pipistrel Alpha Electro Trainers showed up at Fresno, California’s Chandler Airport, all part of the Sustainable Aviation Project.  Described as “a public-private collaboration to reduce the cost of flight training through the use of all-electric general aviation airplanes,” the Project might become a role model for future electric flight training.

On March 19, two 18-wheel trucks delivered two 40-foot shipping containers.  Each container carried two Alpha Electros, two chargers, and a pair of replacement battery packs for each airplane.  It took a mere two hours for a volunteer crew of up to six to remove the aircraft and chargers from the containers, leaving an X-Alpha simulator to be sent on its lonely way to Cypress College in Los Angeles.

Three of the four Alpha Electros after being removed from their plastic sheaths and assembled

Michael Coates reported, “After removing all the plastic wrapping it took about 10 minutes per plane to install the wings and horizontal stabilizers; the way Pipistrel designed the planes makes installation of the wings an easy process especially with all of our helpers on-hand.

“…Coates… was joined by Sabi Apai, the Pipistrel dealer for California who both helped guide the unloading and assembly process and were a great help!

“The planes had been in the containers at sea for 3 months due to incorrect shipping routing by CMA-CGM (dig intended and no apology from them received) where they endlessly sailed the world’s oceans and yet, the batteries were still at from 43% to 53% State of Charge when unloaded. All aircraft were charged to the recommended resting charge of 60-65% the next day.”

A Flight Program That Allows Cross-Country Electric Flight

Joseph Oldham is a driving force behind this electrification of flight training in the Central Valley.  Aircraft and chargers will be fielded at Reedley Municipal Airport (032), William Robert Johnston Municipal Airport in Mendota (M90), Fresno Chandler Executive Airport (KFCH), and Fresno Yosemite International Airport (KFAT).  This distribution was planned by Joseph and Richard Duncan, manager of Fresno Chandler Executive Airport.  Working with project partners including the Cities of Reedley and Mendota, Reedley College, the Fresno Business Council and the CALSTART San Joaquin Valley Clean Transportation Center, they came up with a plan that allows the admittedly short-range aircraft to leave the traffic pattern, fly to a participating airport, recharge, and return.  Cross-country trips will enable student pilots to gain the full gamut of skills necessary to achieve full certification.

Oldham explains in his press release, “We ended up with a unique public-private collaboration … to prove electric airplanes can dramatically cut the cost of flight training, and venture beyond the traffic pattern. The planes are being used to provide flight training for disadvantaged youth in the San Joaquin Valley with a primary focus on youth from the City of Reedley and the City of Mendota, both rural farming communities with high unemployment levels.  We have set up a new non-profit corporation, New Vision Aviation, that will provide the flight training, operate, and maintain the aircraft on behalf of the two cities and we have just completed our instructor training program after getting our instructors validated on the aircraft.  Now is the time for students to take to the skies.”

The Pipistrel Alpha Electro

Michael Coates explained to your editor that the motor powering the Alpha Electro is a product of their own making, and their Information Pack for the airplane adds that it is an Emrax motor modified by Pipistrel for use in this particular airplane.  The Electro 60 motor and controller puts out 60 kilowatts (80.4 horsepower) maximum power for up to one minute and 50 kW (67 hp.) continuously.  Samsung batteries contained in Pipistrel-made battery boxes and controlled by Pipistrel battery management systems (BMS) allow up to an hour in a traffic pattern with a 20 minute reserve for the Light Sport Aircraft version of the plane.  Cross-country trips can last up to 45 minutes with 18 kilowatts consumed at 75 knots (86 mph) from the 21 kilowatt=hour pack.

The strategic positioning of the airports chosen for this training program allows for safe transit between the fields, with each offering the full-service needs of visiting aircraft.  Chargers enable “refills” of battery packs, and spare, fully-charged packs allow five-minute swaps – not any worse than climbing on a ladder, dip-sticking the tank and performing refueling on a conventional airplane.

Low Operating and Maintenance Costs

From your editor’s own experience, a Cessna 150 can consume five to seven gallons of avgas per hour at a cost of $4.96 to $5.55 a gallon, as reported by 100LL.com.  Locally (Aloha, Oregon), Portland General Electric charges residential users a low of 8.8 cents to a high of 18.1 cents per kilowatt-hour of electricity.  The 21-kilowatt-hour pack on the Alpha Electro would cost $1.85 to $3.80 for a full charge at those rates.

Oldham reports in his blog for the project that 100LL and electricity costs in the Fresno Valley area are among the highest in the nation, with avgas at $6.55 per gallon.  Oldham reviews hours and rates for the following: “The aircraft will fly 4 hours per day and operate 6 days per week.  Each aircraft will be fully charged overnight using off-peak electricity at $.18 per kWh for the first hour of flight @ $2.52.  Hour 2 will be charged using partial peak electricity at $.25 per kWh @ $3.50.  Hour 3 will be charged using peak electricity at $.55 per kWh @ $7.70.  Hour 4 will be charged at peak electricity at $.55 per kWh @ $7.70.  This results in a weekday average cost of electricity for 56 kWh per day of $5.35 per hour.  Weekend flights on Saturday will be a flat $2.52 per hour using the off-peak electricity.  Total weekly cost of electricity is estimated to be $117.18 for 24 hours of flight time which yields an average cost of $4.88 per hour.  This estimate is for summer operations.

Sectional of four project airports shows proximity within Alpha Electro range

“During the winter, there [are] no peak demand costs, only partial and off-peak.  In this case the average should be about $.19 per kWh for the 56 kWh used each day or $2.66 per hour.”  These hard numbers will be hard to beat with fossil-fuel powered equivalent aircraft.  Since the Alpha Trainer with the Rotax 912 UL engine burns a mere 2.5 gallons of 100LL per hour, fuel costs will be around $11.00 or $12.00.  That doesn’t include the higher maintenance costs for the Rotax, though.

Titan Aircraft lists a new 912 UL at $14,337.  Discussions on the web suggest that the UL engine will achieve 2,000 hours between overhauls.  Many rebuilders like Brian Carpenter suggest selling the engine at that point and getting a new one from the factory.  Core engines seem to fetch $2,000 to $3.500, so the replacement ends up costing about $12,000, or $6.00 per hour.  Of course, maintenance, oil changes, spark plugs, etc. run that number up considerably.  As noted above, direct operating costs for a traditional trainer such as a Cessna 150/152 can top $30 an hour just for fuel.

By contrast, Pipistrel’s Electro 60 motor consumes relatively little energy and has two overhaul periods at a TBO of 2,000 hours, and according to numbers from the Pipistrel Alpha Electro Information Pack an overhaul cost of 500 Euros ($616) plus 12 hours of labor.  With a motor life limit of 6,000 hours, replacement will cost about 10,000 euros ($12,320).

If the Sustainable Aviation Project can achieve FAA certification and approval for their aircraft and training program, we could see an inexpensive route to attain private pilot ratings, and once-again busy private fields in rural areas.  This regional approach to flight was envisioned by William T. Piper, and the Alpha Electro could be a worthy successor to the iconic Piper Cub.

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Swiss Movements – aEro 1 and aEro 2

Electric Flying Inspires Bigger Plans

Dufour Aerospace, based in Visp, Switzerland, and within sight of the Matterhorn, has been flying aEro 1, a Silence Twister-based electric aerobatic craft, for the last two years.  Read the pilot report on the surprising performance and the quiet flight experience in the aEro 1 to get some idea of how future flight will be a welcome relief from the noisy today’s noisy passage.  “Electric motors are so incredibly efficient. They have a huge torque and you will take off much faster than with regular engines. Our aEro 1 takes off after 70 meters of runway – at 2/3 of the available power.

“The first real takeoff and flight afterwards was really mindblowing. I set the power, took off, and checked the instruments, especially the engine instruments. And checked the engine instruments again. You hear the slow roll down of the tires as they stop turning. (Have you ever heard that in a powered aircraft?) You hear the wind noise around the fuselage. Flight with an electric aircraft is far quieter: you do not feel the motor running, there are no vibrations and you feel the wind and the air around you. It truly changed my view on electric flight.”

aEro 2 is Under Development

These comments from Thomas Pfammatter, one of the co-founders of Dufour Aerospace, help us understand why he and partners might be intent on expanding into greater horizons for electric aircraft.  Now the company is promoting its sky taxi vision, a simplified form of the vertical takeoff and landing (VTOL) vehicles being developed worldwide.

aEro 2 promises, according to its builders, “An advanced electric aircraft that brings you from your doorstep to nearly anywhere you want over 5 times faster than a car but at the same cost per kilometer.”  That phrase, “per kilometer” is important, since distances by air (as the crow flies) are usually shorter than road distances, with meanderings through rural and urban landscapes.  The example shown below yields a significant distance advantage to the aircraft, and an argument-settling savings in time.  Even an average wage earner would see a cost savings in the Dufour aEro 2’s travel time.

Perhaps a cherry-picked example: mountain roads are certainly more challenging than straight-line flight

The firm has been carrying out detailed simulations of the anticipated flight characteristics and plans on testing a 1/3-scale prototype by October of this year.  Full-scale construction will begin in November, 2019, with initial ground tests taking place by the end of 2020.

Simplicity and Technology

The designers herald several design features that provide beneficial aerodynamics and handling for the craft.  The large, tilting wing provides “constant airflow over the wings, [giving] unmatched stability and control even in very slow flight.”  The large wing surface “makes it less vulnerable to vortex ring state in hover than any other aircraft.”  The wing enables a 12:1 glide ratio if all power fails, and a ballistic recovery parachute can safely bring the entire aircraft and passengers to a safe landing if necessary.

Two motors on each rotor allow interconnection between all four motors, with the airplane actually able to land with only one motor providing power to both rotors.  This is more easily done with electric power than with aircraft relying on mechanical interconnection between power sources.

Using electric power only, aEro 2 can travel 120 kilometers (74 miles) at 180 kilometers per hour (111 mph).  Hybrid power enables 300 kph (186 mph) over 800 kilometers (nearly 500 miles), greater hover times, and instrument flight rules (IFR) capability.

Quiet operation will enable aEro 2’s use in urban settings, and its ability to perform VTOL or STOL takeoffs and landings will give it the flexibility to use a great number of existing operational areas.

Thomas Pfammatter and co-founders Dominique Steffen and Jasmine Kent, have demonstrated their ability to launch a practical aerobatic single-seater with aEro 1.  That airplane is scheduled to receive a doubling of endurance and range with a new battery pack, making it even more practical.  aEro 2 will doubtless benefit from the team’s ongoing search for improved solutions for future flight.

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From Anime to Low-Powered Electric Flight

A team in Japan has flown a low-power electric canard motorglider, and is now building a more conventional, lightweight electric aircraft.  Members of Aircraft Olympos Ltd. on the large island of Hokaido have been instrumental in building and flying everything from a jet inspired by one of Hayoa Miyazaki’s anime productions (Nausicaa (Dove) Of The Valley Of The Wind – 1984) to some fascinating electric aircraft.

Brian Carpenter met Tota Ueno, a worker on the project, and visitor at one of Brian’s maintenance classes in Corning, California.  Brian was selected by the National General Aviation Awards Committee as the recipient of the 2017 National Aviation Maintenance Technician (AMT) of the Year Award.  His classes in ultralight aircraft maintenance and two-stroke engine repair and maintenance obviously draw a worldwide audience.

Beyond that, he has been developing the EMG-6 ultralight, which can be powered by traditional two-stroke engines or one or more electric motors.  He’s been testing a series of motors and recently selected a Rotex package from the Czech Republic as a viable power system.  (More on that in an upcoming blog entry.)

Of course, he’d be interested in Ueno’s work with a highly creative group in Japan.  Beyond the anime-inspired machine, they have built very light, electrically-powered machines that manifest a different kind of flight – slow and elegant.

The team’s SP-1 solar-powered craft is a derivative of their canard glider, or SC-1.  Plans are available from the group, with the .pdf version available for 3,000 Yen (a little over $28 USD).  A1-size drawings are 2,800 Yen each ($26.31), or 69,800 Yen ($656) for the full 36-drawing set.

Note the controllable-pitch propeller and interesting solar fabric on the wings.  Most solar-powered craft such as the Solar Impulse or Eric Raymond’s Sunseekers have rigid panels encapsulated into the structure.  This fabric, as can be seen in the in-flight views, ripples in the airstream.

One wonders if the group, which has been in operation for over 32 years, designed and built their own 2.2 kilowatt motor, or if they chose some industrial design.  The chain drive allows a large propeller to turn slowly, essential to high efficiency.  For the 86-kilogram (189 pound) machine, this combination obviously allows flight in ground effect, with a mere 700 Watts necessary to maintain level flight.  Gunther Rochelt’s earlier solar-powered airplane, Solair 2, was able to maintain level flight on 755 Watts out of ground effect, so this is still impressive performance on what is essentially model-airplane power.

Olympos is working on a more conventional design. The FOP-01 Primary/Electric Motor Glider.  One hopes for their success and that they might share plans for this upcoming design.

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Recent news shows aerial drone delivery of small packages from an Amazon Warehouse or pizza from the nearest Dominos, but such packages are lightweight trifles compared to the 700 pounds Chip Yates promises to drop from the sky.

Such loads are necessary in conflict and disaster areas, where material heavy enough to hold off an enemy or feed hordes of refugees is essential.  Fifty-kilogram sacks of rice or electric generators are necessary for survival, and a heavy-duty delivery system will almost always come in handy.

Chip, head of Yates Electrospace, has gone over 200 mph on an electric motorcycle, taken the UQM motor from that machine, and powered his Long-ESA aircraft to also top 200 mph.  As Aviation Week and Space Technology notes in its March 26-April 8 edition, “It is ironic, therefore, that the first product from his company… should be an unmanned cargo glider.”

Silent Arrow is shipped in the box that becomes the glider which delivers a 700-pound payload

It’s the Silent Arrow, delivered in its own box, which becomes the fuselage for the pointy-nosed delivery drone.  Designed to be dropped from large aircraft such as the CH-53K, MV-22, or C-130, the GD-700 looks a great deal like a military container, or the heavy-duty sound systems lugged about by rock group roadies.  The wings are folded lengthwise in the box as delivered to its user, who merely has to release a series of catches, pull the top up and flip it over to reveal the tandem wings which can flip into flight positions after the newly refilled container is dropped out of a delivery plane.

Flip the top over and put the pointy-end forward to turn the box into a cargo glider.  Wings deploy into full tandem configuration when dropped from mother aircraft

Unlike parachute deliveries, in which the ship carrying supplies must be flown precariously close to a battle or disaster zone, the delivery craft can “stand off” at a distance (23 to 49 miles) at an altitude of 12,000 to 25,000 feet, safe from shoulder-fired missiles or ugly weather or terrain.  When the GD-700 leaves the mother ship, its wings flip out and it can be guided to a landing zone, where it alights with loss drama than it would if coming straight down in a parachute.

Silent Arrow deployment, flight to designated landing zone

A motorized version will enable release at even greater distances from the target, giving a higher degree of safety to the flight crew.  Where the unpowered version is seen as disposable, the electrically-powered ER-700 can be reused.

At about $10,000 for the unpowered version, even a one-time use makes for inexpensive delivery of necessary supplies in hazardous situations.  There is no official word on the powerplant for the ER-700, or what additional costs will apply.  Yates Electrospace is currently working to fulfill an initial order for 10 GD-700s, six of which are undergoing wing-deployment testing with the U. S. Marine Corps Warfighting Laboratory (MCWL) in preparation for full flight tests.

In Other Chip Yates News

Not content for mere 200 mph speeds with the Long-ESA, Chip is developing a VFP (Very Fast Plane) intended to push the electric speed record into the 400 mph range – or beyond.   Chip says the airplane “Looks like a bullet,” and will have four UQM 250-kilowatt (335-horsepower) motors driving propellers (note the plural) from Craig Catto.  According to Aviation Week, two of the new motors have been tested on a custom test stand, driving contra-rotating props “with good results.”  With all four motors running, the VFP will be the first megawatt electric airplane, according to Chip.

Yates test stand testing conro-rotating propeller setup for Jeff Engler’s Wrght Electric airliner

This is possibly the test stand on which motor and propeller testing for Jeffrey Engler’s airliner project has taken place.  Regardless, Chip Yates is not content to let laurels rest easily on his brow, preferring to constantly challenge even his own best efforts.

 

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Zee?  Kitty Hawk? Cora?

Different Names, Different Configurations

Zee, One of two aircraft companies funded by Google founder and CEO Larry Page, has been a highly mysterious business.  Its web pages mostly gave discrete job descriptions for those willing to sign up for a mostly undefined mission.  Occasional glimpses of patent drawings, spy shots of a multi-rotor craft in Google’s Mountain View, California parking lot came into view, and later, in-flight shots of other, different looking craft came from Hollister, California.

Kitty Hawk, the other company funded by Larry Page, seems to have subsumed Zee and produced a 12-rotor, single-propeller aerial taxi about the size of a Cessna 150, but capable of vertical takeoffs and landings and seamless transitions to forward flight.  A white example has flown at Hollister airport and a yellow version at a field in New Zealand.

An Almost Epic Journey

The intellectual, physical and geographical journey of this craft is almost epic, and seems to have resulted in a 13-motored machine that can fly the length of a runway, hover, and alight gently.  The background and changes of corporate identity are a bit daunting, and the story comes to light here.

One of Zee’s original patent drawings

A short form of the story, from the Vertical Flight Technical Society online Electric VTOL News, squeezes the story to three succinct paragraphs:

“The effort began in March 2010, originally under the leadership of Prof. Ilan Kroo of Stanford University. Patent 9,242,738 (priority date July 19, 2011) illustrates a high-mounted series of vertically mounted electric propellers similar to Z-P1.

Looking a great deal like the patent drawing

“The first vehicle, the Z-P1 Proof of Concept (POC) made its first unmanned (self-piloted) hover in Dec. 2011, and in Feb. 2014, completed its first transition. The aircraft demonstrated flights up to 60 mph (100 km/h) with vertical take-offs and landings. The manned Z-P2 aircraft made its first flight in late 2016 or early 2017; in August 2017, the Z-P2 made its first transition.

Z-P2 flight test in Hollister, CA. Note that wing has been added, configuration severely changed

“Testing of the Z-P1 and Z-P2 led to the initiation of the two-seat Cora demonstrator, and the subsequent Zephyr testing in New Zealand.”

White Cora probably flying over Hollister – although both this and yellow version seem to both now be in New Zealand

Sebastian Thrun and Ilan Kroo Initiated Zee

Zee, the first iteration of Google’s drive to bring flight to everyone, was started by Sebastian Thrun, widely acknowledged as the father of driverless cars.  With Google cars and Zee springing from Mountain View, California roots, Thrun oversaw imaginative approaches to making transportation cleaner and safer by land and by air.

Ilan Kroo’s biography on Linked In gives this review of his early and ongoing efforts for what has become Cora.  “Took a leave of absence from Stanford from 2010 to 2015 to start Zee.Aero.   As first employee and co-founder, built a strong team of over 100 aerospace engineers to develop new concepts on personal air transportation.  Returned to Stanford in 2015, but continue to spend time at Zee as Principal Scientist.”  He has also designed the Swift ultralight tailless sailplane, among other accomplishments.  A trip to the Hiller Aviation Museum in San Carlos, California reveals several NASA designs that are products of his fertile imagination and refined engineering skills.

He has initiated and guided the different design efforts from inception in 2010 to the current two-seat prototype and apparently tested a variety of configurations.  Cora has only a glancing similarity to the original patent drawings.

At this point, though, Eric Allison has assumed the position of Vice President of Engineering for the firm and continues flight testing in New Zealand, which has been generous in welcoming Kitty Hawk to the country.   Note that the name has changed to Zephyr Airworks (Kitty Hawk in New Zealand) and that Fred Reid is CEO, with enthusiastic support from the country’s Minister for Research, Science and Innovation.  An apparently open-minded promotion of clean aviation enables unfettered flight testing to go forward.  (Although there are seven test ranges in America that might suffice.)

Interesting Features on Cora

The designers and builders have incorporated some interesting features on Cora.  The 12 “lift fans” seem to be an integrated motor/propeller unit, and are set at varying angles to the horizontal.  The motors are probably axial flux, but also incorporate axial cooling vanes in their perimeter.  The wide fan blades seem to be molded into the top cover for each motor.

Reviewing in-flight pictures of Cora and earlier test vehicles, the fans seem to have different angles in different shots, showing that they probably change position to control lateral or pitch movements of the machine.  This would add a level of complexity to controls not experienced with systems like eHang’s, where the propellers maintain a constant angle to the horizontal axis of the vehicle.

Cora has undergone eight years of development and seems to have a high degree of refinement.  Don’t look for a Cora dealership in your neighborhood soon, though.  Kitty Hawk intends this for use in on-call ride services.  All you will need is a smartphone to call your ride.  The video below repeats some material from the first but provides additional information on the plane’s development.

With Joby Aviation reportedly flying its autonomous vehicle around the California Coastline, eHang testing its one- and two-seat pods with its entire board of directors, Vahana hovering over the eastern Oregon plains, and Autonomous Flight making journeys along the south coast of England, several VTOL systems are openly or surreptitiously taking flight.  Cora seems to be coming out from a long period of only occasional glimpses.  Let’s hope that all these enterprises succeed and prosper.

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The Vertebrate Battery

“Prof. Yuan Yang of the engineering school at Columbia University (New York) modeled, designed, built, and fully evaluated a configuration that emulates the spine of vertebrates, while providing 85% of the energy density of a prismatic Li-ion cell with equivalent volume.” According to Power Electronics.com.

Professor Yang’s 14-member team, working in the impressively-named Center for Precision Assembly of Superstratic and Superatomic Solids, and  inspired by the flexibility of the human spine and its ability to repeatedly endure bending and twisting, designed a battery that emulates the characteristics of what is in essence a structural battery.  We know from experience that our backbones can perform some pretty extraordinary twists and turns – witness the supple routines of gymnasts and Cirque de Soleil performers.

In the flexible spine-like battery, the vertebrae correspond to thick stacks of electrodes and soft marrow corresponds to unwound part that interconnects all the stacks (a). To fabricate the spine-like battery, multilayers of electrodes were first cut into designed shape; then strips extending out were wound around the backbone to form spine-like structure (b). (Credit: Yuan Yang/Columbia Engineering)

Our spines are not rigid assemblies, but a complex construction of solid parts (vertebrae), flexible bits between the vertebrae (disks), and a network of wiring (nerves), which transmit signals from our organs and extremities to the brain and back.  The electrolytes carried in our blood and circulated throughout our body help power the constant brain/body interactions.  This pitifully lay version of things can give only a hint of what really goes on in this marvelously complex system.

In the flexible spine-like battery, the vertebrae correspond to thick stacks of electrodes and soft marrow corresponds to the unwound part that interconnects all the stacks (a). To fabricate the spine-like battery, multilayers of electrodes were first cut into designed shape; then strips extending out were wound around the backbone to form spine-like structure (b). (Credit: Yuan Yang/Columbia Engineering)
Sufficient similarities between what happens in our bodies and what transpires in batteries led research Yang to devise a battery that allows the flexibility of the spine with a resilience that seems surprising, given the explosive characteristics of conventional lithium batteries.  YouTube abounds in videos of batteries being subjected to various forms of bending and poking, with fiery results.

Yang’s YouTube evidence shows his batteries undergoing repeated flexing at high speed without crying “Uncle!” as our own spines might.  This durability would be of great use in wearable electronics, and might have a place in grander mobile structures.

Researchers cut what started as conventional anode/separator/cathode/separator “stacks” into long strips with multiple branches.  They then wrapped those strips around the backbone “to form thick stacks for storing energy, like spinal vertebrae.”  Energy density in this spinal form is a “function of the ratio of the longitudinal percentage of vertebra-like stacks compared to the whole length of the device, and can reach over 90% in theory; the prototype was very close at 85% (242 W-hr/L – Watt-hours per liter).”

To verify mechanical integrity, researchers cut open the post-test battery and found “no obvious cracking or peeling from the aluminum foil, confirming the mechanical stability of the design.  Even better, flexing seems to have caused no changes in the voltage profile during the entire discharge cycle of the battery.

The team’s paper, “Bioinspired, Spine-Like, Flexible, Rechargeable Lithium-Ion Batteries with High Energy Density,” was published in the January 2018 issue of Advanced Materials.  Although the paper is a pay-per-view item, 12 pages of supporting illustrations and the two videos shown here are not.

Flexible and Strong Enough for Aircraft?

If this material will work for watch and FitBit bands, or provide heat for skier’s parkas, would it not be a candidate for use in future aircraft structures?  Your editor has been an advocate for what he calls the Grand Unified Airplane, a vehicle that would pull energy from the air and sunlight through which it flies.  This type of battery could provide energy storage and structure in an all-in-one component – or even a complete airframe.

Thanks to Patrick McLaughlin for sharing the source material for this entry.

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Get Your Flu Shots

Your editor apologizes for the two-week hiatus in blog entries.  He was popped into Intensive Care on Valentines Day with a particularly debilitating flu, and is just now spending more time upright than supine since that event.  Things are happening, so as strength and resolve return, you will be among the first to follow some pretty exciting events.  Thank you for your patience.

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