AEAC Debuts Sun Flyer at AirVenture 2014

Calin Cologan and George Bye staged a joint press event on the Sunday evening before AirVenture started.  Held in the Redbird Tent on Wittman Field, it drew hundreds who saw the Redbird flight simulators and a Diesel-powered Cessna, but were stopped short by the yellow and blue Sun Flyer, a single-seat proof-of-concept version of what will soon be a two-seat battery/solar training aircraft.

Forming a new firm based on the strengths of PC-Aero in Germany, and Bye Aerospace and Redbird Flight Simulators in America, they promise an electric training aircraft for the near future.  Unlike the tandem two-seaters PC-Aero is developing in Germany, American Electric Aircraft Corporation will produce a side-by-side craft, often preferred for communication between instructor and student.

In this Da Vinci Institute presentation, George Bye discusses the keys to performance for his aircraft, which include clean aerodynamics, high efficiency, a light carbon structure, and solar energy.  Nest will come a “big performance step – endurance” – and possible perpetual flight like that demonstrated by the much bigger, less practical Solar Impulse and being approached by Eric Raymond’s Solar-Flight Duo.

Part of AEAC’s strategy is to use proven off-the- shelf components, advanced technology, miniaturization, and emerging aerospace design to bring a complete, modern machine onto the training scene.  The strategy will bring flexible, innovative, and scalable design and manufacturing techniques to the fore, enabled by an experienced team with years of aerospace expertise.

Stealth is Good for Civilian Aircraft, Too

Sun Flyer, as with other electric aircraft, has several aspects that make it commercially-viable for training or unmanned use, including a low heat signature that comes from the lack of  hot exhaust.  Large, wide propeller blades turn slowly, giving half the acoustic signature of conventional small General Aviation aircraft.  The unobtrusive nature of the airplane allows the unmanned version to stay, listen, and watch – highly attractive to the Defense Department.

StratoAirNet UAV with potential military and civilian uses

StratoAirNet UAV with potential military and civilian uses

This leads to a concept developed by Bye and Gologan, StratoAirNet, a persistent network of medium-to-high altitude aircraft that can provide applications in “communications, border patrol and homeland security, maritime search and rescue, visual and thermal reconnaissance and forward air control. Potential civil applications include traffic control, pipeline and power line inspection, aerial law enforcement, wildlife and natural resource monitoring, forest fire detection, weather monitoring and aerial photography.”

Characteristics that allow low-cost surveillance equate to reasonable operational costs for flight schools.  Part of that is the low empty weight of the concept airplane, 150 kilograms (331 pounds), with batteries adding 80 kilograms or 176 pounds to that.  In the surveillance version, this allows a payload of 150 pounds.  For the trainer, LSA-type numbers will prevail, with an empty weight of 280 kilograms (616 pounds) empty weight including batteries, a payload of 200 kilograms (440 pounds), and a flying weight of 600 kilograms (1,320 pounds).  The poster at the Redwing tent showed a power output from the Eck/Geiger HPD-25 motor of 26 kilowatts (34.8 horsepower) continuous and 30 kW (40.2 hp.) peak power for a limited time.

Shari Rossi, a member of the AEAC Board of Directors, shows a light touch on the Sun Flyer

Shari Rossi, a member of the AEAC Board of Directors, shows a light touch on the Sun Flyer

The nine-kilogram (20-pound) motors give twin-motor safety with single-motor operation.  Dual controllers add about two pounds to the power system.  Two throttles can be individually operated, or combined to use the full power of both motors for takeoff or climb.  Since the clean, light airframe requires only six kilowatts (8 hp.) to maintain level flight at 50 knots (57.5 mph), the airplane should be able to stay aloft for over three hours on its 18 kilowatt-hour battery pack at that speed.  At full throttle(s) it can climb 700 feet per minute.  Of course, normal training regimens will include tough-and-goes, maneuvers, and higher-speed operations that will reduce that best-glide-speed type endurance.  Some indicators show a 52-kW (70-horsepower) version of the dual motor may be available, which would certainly enhance climb performance.

To augment that, the airplane has Solar World thin-film photovoltaic cells that can add a maximum of   up to 1.3 kW of energy.  These cells add minimal weight for their 7 square meters (75.3 square feet) of conservatively-calculated area.  According to Calin Gologan, “The cells weigh about 0.5 kilogram (1.1 pounds) per square meter, the layers 0.2 kg (0.44 pounds).”  Wiring adds about 0.1 kg (0.22 pounds).  This totals about 0.8 kilograms (1.76 pounds) per square meter, or about 0.16 pounds per square foot.  The seven square meters of solar cells thus add about 12.3 pounds to the aircraft’s weight.  Since they are 22-percent efficient, Calin calculates them as providing 220 Watts per square meter, or a maximum of 1.54 kW, about 20-percent of the energy required for low cruise. Calculations for endurance are based on the currently installed batteries and their 250 Watt-hour per kilogram performance.  AEAC anticipates having 400 Watt-hour per kilogram batteries soon.

The cells cost about 350 euros ($465) per square meter, two layers of thin glass laminations which form a flexible and protective matrix cost about 660 euros per square meter, and this totals about $1,000 euros ($1,330) per square meter ($124 per square foot). The solar cells add 7,000 Euros ($9,310) to the cost of the airplane, but allow free recharging of the batteries as the airplane is parked, and add to the endurance and range in the air.

Note that Charlie Johnson estimates a price for the two-seat trainer at under $180,000, certainly not out of touch with the market or out of line with other LSA-type aircraft.  AEAC has a truly disruptive card up its sleeve, though – an operating cost of $10 per hour, including an hourly allowance for battery replacement.   Calin, George and Charlie all hope this will lead to a resurgence in flight training and a rebirth of the General Aviation market.  Coupled with new aircraft promised from Airbus and rising interest in electric ultralights, we may soon witness a quiet buzz at our local flying fields.



Ring Around the Tail Boom

Call it Kismet, but three aircraft builders in wide-spread locations have recently announced similar approaches to putting a pusher propeller on the tail boom of three different ultralight sailplanes.  Each enjoys the benefits of mounting a propeller on a rear portion of a pod-and-boom fuselage: streamlining the folded propeller into the wake of fuselage/wing junction, enabling use of a large propeller, and turning the prop slowly to get the greatest efficiency from a small motor.

Moyes Tempest from Down Under

“Bodex,” a pilot in Brisbane, Australia write, “A mate and I managed to acquire two old Moyes Tempests last year. Although they fly well for what they are, we wanted to see if it could be converted to electric in the hope of getting a self-launch from it.

Moyes Tempest is ultralight sailplane that might lend itself to self-launching

Moyes Tempest is ultralight sailplane that might lend itself to self-launching

“Originally the idea was going to mount the motor behind the fuselage under the boom, but ground clearance was a problem. Then we thought nose mounting, ground clearance again…even with a dolly launch idea.

“We then thought about a boom mounted pusher prop…. The idea was to have the reduction pulley mounted on the tail boom using a roller bearing, the carbon prop blades then bolt to the pulley which is driven from the drive shaft below.

Plettenberg Motor drives larger diameter propeller drive mounted on large bearing around tail boom

Plettenberg Motor drives larger diameter propeller drive mounted on large bearing around tail boom

After a two-stroke engine failed to live up to hopes, the builders used an available Plettenberg predator 37 brushless outrunner from an electric trike and within 10 minutes, the airplane was ready for a test run.  The reduction drive was based on the gas engine’s 7,500 rpm to give about 2,600 rpm at the propeller.  The Plettenburg would require 65 Volts to turn over at the appropriate speed, “So I decided on an 18s[eries] lipo pack. I ordered 8x 8s 5800 mah packs from Hobby King and wired them to a [battery management system -BMS] in a 16s4p[arallel] configuration to give me 23.2Ah of usefulness. The pack came out at 7kg (15,4 pounds) and charges and balances through an inbuilt BMS.”

“To control the power I used an Alien power systems 450A speed controller. A linear pot running through a servo tester provides the signal. A [high voltage] contactor provides a safeguard between the battery and controller; two switches on the throttle quadrant control everything in the aircraft. A Vincon battery monitor provides data on power used, current draw, voltage, time to go, etc.”

Two test flights showed that at least after an initial aero tow the airplane could manage a 200 fpm rate of climb, even though full power was not available because of a programming error.  The second flight brought about an overheated controller, so the partners are taking time to regroup.

e-Sirius from France            

The Club d’Ultra Léger d’Alsace,  a group of French enthusiasts in Strasbourg, France, recently announced “A new concept of electric brushless outrunner motor mounted on the motor glider Sirius C with the motor around the tube fuselage and the propeller blades fixed on the outdoor circumference of the rotor.

Ultralight Sirius C motorized by Club d'ultra legere of Alsace, France

Ultralight Sirius C motorized by Club d’ultra legere of Alsace, France

”The advantages of such a solution are:

- Use [of] a large folding propeller

- Minimum drag of all motor and propeller

Similar to system on Australian Tempest, large bearing, folding propeller on Sirius' tail boom

Similar to system on Australian Tempest, large bearing, folding propeller on Sirius’ tail boom

- Good ventilation of the motor and the controller

The batteries are housed near the motor in the very sharp cockpit profiling.”

Unfortunately, the club did not give further details on the motor, controller, or batteries used.

GFW-4 from Germany

Dr.-Ing. Gerhard Friedrich Wagner from Kaiserslautern, Germany has a slightly more sophisticated version of this configuration in his GFW-4, a self-launching ultralight sailplane in the 120 kilogram (264-pound) class.

Three-view drawing of GFW-4 shows the clean design, potential for great ultralight gliding performance.

Three-view drawing of GFW-4 shows the clean design, potential for great ultralight gliding performance.

The rear half of the GFW-4 will include 10 kW outrunner motor, with the three-blade propeller “lay at rest, streamlined in the recesses provided in the co-rotating outer rotor sleeve.”  A “cooling air control,” mounted ahead of the motor, provides “sufficient cooling air.   The battery is in a separate, removable housing.

The fuselage is a sandwich shell made of plywood, foam, glass-reinforced plastic (GRP), and carbon-fiber reinforced plastic (CFRP).  Its 13.2 meter (43.3 feet) wing can enable the 239-kilogram (526 pound) airplane to reach a 34:1 glide ratio, certainly enough to find a thermal with a little electrical nudging.

Construction is well underway, and we’ll look forward to seeing how Dr. Wagner fares with his latest creation – and how similar efforts in France and Australia succeed.  Good luck to all!


Aaron Singer, owner and operator of Seaplane Adventures, San Francisco with his wife Tiffany, gave an excellent assessment of why we don’t see more electric seaplanes in the mix of products coming into play.  Pointing out that most water-borne efforts so far have been ultralights, such as Dale Kramer’s e-Lazair amphibian, he gave examples of the energy necessary to lift off from water and the how that plays in the daily use of a DeHavilland Beaver and Cessna 172 in which his team flies tourists around the Bay Area.

Their web site explains their mission.  “The Singers bought San Francisco Seaplane Tours in January of this year and have rebranded the company as Seaplane Adventures and revamped the operation with a new logo, new energy and 100% passion for flying seaplanes in the Bay Area. We are in the Happy Business – it’s our job to bring to you a safe, exhilarating, beautiful, one-of-a-kind experience flying in a seaplane over San Francisco!”

For an 18-minute version of this video, try this link.

Singer gave a brief history of seaplane flight, showing that seaplanes were prevalent when there were no airports, even though they require more power to overcome the drag of water on their hulls during takeoff. explains the steps in getting a seaplane to lift from water.

The hydrodynamic  drag builds to a “hump” at the apex of power required to break free from the water.  A seaplane goes through four phases in taking off according to

(1) The “displacement” phase,

(2) the “hump” or “ploughing” phase,

(3) the “planing” or “on the step” phase,

and (4) the “lift off.”

Diagram shows engine thrust required to overcome drag of hull or floats on water, with critical "hump" to be overcome before flight is possible

Diagram shows engine thrust required to overcome drag of hull or floats on water, with critical “hump” to be overcome before flight is possible

A displacement hull is simply one that sits in the water, and can be motivated by oars, sails, or some type of paddle-wheel or screw arrangement.  Its speed is limited to a number derived from the hull length (wildly oversimplified).

As a boat, or seaplane hull or floats begin to move forward faster, the airplane develops enough lift to start pulling the machine out of the water, it reaches that “hump” phase, where the greatest power is required.  Once the seaplane’s hull or floats are “on the step” and planing partly above the water like a high-powered speedboat, the airplane accelerates more easily and quickly reaches takeoff speed.   According to Singer, the “hump” is the biggest problem for electrification, requiring 1/3 of the total power used in a flight for ½ the weight that an electric seaplane will carry for the necessary batteries.   An air taxi, such as those he and Tiffany run, would require additional energy storage because of the repeated demands made on their seaplanes each day.

To start on what will probably be a long research study of how much additional power is needed to get a seaplane over the hump, look at this X-Plane’s tutorial on the Froude Number, a non-dimensional figure as important to boats and seaplanes as a Reynolds Number is to the aeronautical design of airplanes.  In fact, the Froude Number can help define the transition from laminar to turbulent flow, a big consideration in airfoil design, for instance.

The need for quick turnarounds would require either battery swapping or fast charging capabilities.  With tourists keeping Singer’s airplanes busy all day, downtime is not an option.  For designers who want to create a personal seaplane, though, such considerations are simplified or even eliminated.  Thomas Brodeskift, for instance, has been designing and crafting a two-seat, hybrid-powered amphibian for several years now, the Equator P2 Excursion.

Whether you decide to head for Mill Valley to ride with Aaron, or want to be the first to fly an Equator P2, seaplane flying brings an added dimension to aerial sports.  Let’s hope that electric power can add further to that dimension.


2X Solid State Batteries?

Applied Materials, located in Sunnyvale, California, designs and makes equipment used in the manufacture of computer chips and other miniature electronic devices.  Your editor worked there on assignment from his engineering firm for six months 15 years ago, documenting and verifying the equipment and control systems for their newest facility.  Even then, miniature was wild understatement, with the company crafting machinery that could produce 0.18 µm lines in silicon chips.  In the last two decades, line widths have shrunk to 0.03 µm, and the number of elements on chips has increased proportionally.  This makes nano manufacturing a highly precise endeavor, and one which seems to defy credulity with lower costs for the ever-increasing number of chips being made.

Toyota's chart showing promise of solid-state battery as interim device between current Li-ion and Li-Air batteries

Toyota’s chart showing promise of solid-state battery as interim device between current Li-ion and Li-Air batteries

It’s this type of manufacturing expertise which makes possible the electronic life we lead today and one that relies increasingly on energy storage technology.  The very things that make solid state computing possible could produce solid state batteries – an advantageous storage medium – if they can be produced in commercially viable quantities at a reasonable cost.  MIT Technolology Reports quotes an Applied Materials scientist on this challenge.  “’The thing that’s holding [solid-state batteries] back is materials processing and the cost,’ says Andy Chu, head of product marketing for energy storage solutions at Applied Materials. ‘We’re addressing these problems. That will allow you to take this to high volume.’”

Such batteries are available, but at high cost and therefore in limited applications. Applied Materials thinks it can make these batteries much cheaper using its manufacturing expertise.  The company’s confidence is interesting, considering that Sakti3, Ann Marie Sastry’s firm, has been forging ahead on the commercial realization of solid-state cells with “robust processes” and scalable production systems, and that Toyota was reporting on its solid-state battery in 2010 – although they’ve only tested one on a small scooter so far.

Solid-state batteries replace the liquid electrolytes used in normal lithium-ion cells with solid ones, which according to the MIT article, “make it possible to replace conventional electrodes with lithium metal ones that hold far more energy.”  Liquid electrolytes help fuel the flames during thermal runaways in conventional batteries, so their absence in solid-state batteries results in greater safety.

Toyota scooter powered by prototype solid-state battery

Toyota scooter powered by prototype solid-state battery

MIT’s article doesn’t specify to whom the tools have been shipped, but notes, “The manufacturing tools shipped so far by Applied Materials, which perform extremely high-precision deposition of materials over large areas, will be used initially for prototyping and demonstrations of solid-state batteries.”

This ability to produce electrode and electrolyte materials “over large areas” is a big challenge.  The process requires depositing layers of contacts, electrodes and solid electrolyte in succession, and without gaps in the electrolyte that would lead to short circuits.  Applied Materials claims to have conquered this challenge, and that un-named customers are now producing batteries with its tools.  The company is also reticent about how much energy these existing batteries can store, how much they cost, or how quickly they can be recharged.  Applied Materials will admit that their solid electrolyte is not yet as conductive as liquid equivalents, and therefore limits power output.  The firm would also like to increase the speed with which their tools can deposit “energy-storing materials” faster, to produce thicker layers that store more energy.

First commercial applications will probably be in wearable items such as watches, or even in the watch bands.  Because the batteries don’t have to fit the cylindrical or pouch-type form factor of more conventional energy storage cells, they could be incorporated in say, wing-shaped areas, or tucked into form-fitting nose cones.

Despite all the caveats and side-steps, MIT suggests that these batteries may be capable of storing twice the energy of existing lithium-ion cells or lasting twice as long in use.  It may not be the promised land of the 10X battery, but it would be a significant advancement for electric vehicles.


No hype, Pipistrel’s Hypstair (hipster) was introduced by Tine Tomazic and Gregor Veble at this year’s Electric Aircraft Symposium.  The attempt to bring the world’s first certified hybrid aircraft to market is a joint venture by Pipistrel with partners Siemens, the University of Maribor, the University of Pisa and MB Vision, a specialist in providing visual information.

Hypstair will integrate batteries and power train into a modified Panthera airframe

Hypstair will integrate batteries and power train into a modified Panthera airframe

Siemens, as might be imagined, is providing an “ultra-light weight integrated drive train” for the aircraft,”  Slovenia’s University of Maribor the HIL (hardware in the loop) evaluation for electric motor control testing and dynamic emulation of mechanical loads, Italy’s University of Pisa for evaluation of hybrid technology advantages, and MB Vision for development and integration of the aircraft’s interior and human machine interfaces that will make the information presented to the pilot ideally selected and intuitively perceived.

Wing-mounted batteries follow spar to distribute load of 5 serial/12 parallel modules

Wing-mounted batteries follow spar to distribute load of 12 serial/5 parallel modules

Far removed from the days when homebuilt aircraft advocates drew a chalk outline of the steel tubing they would weld together on the garage floor, the developing discipline of mechantronics stives to unite mechanical, electrical, telecommunications, control and computer engineering to produce integrated products that function at high levels.  Such an approach will lead to aircraft that perform at the best possible levels, and a piloting experience intended to meld the pilot and the airplane in a thoroughly new and different way.

HMI design will lead to standardized cockpit environments, lower workloads for pilots

HMI design will lead to standardized cockpit environments, lower workloads for pilots

Tine and Gregor focused on the hybrid propulsion system for Hypstair, a serial hybrid drive that would lead to much quieter aircraft with greater fuel efficiency.  Hypstair will allow validation of components, many already integrated into the airframe.  The power system will swing a low-RPM, five-bladed propeller, ensuring low noise.  To make sure the internal combustion engine, electric motor, controller and batteries stay within safe operating ranges, the sleek cowling has three openings, each tuned to its respective need.  A dedicated battery management system (BMS) will actively balance cells in the battery pack, maintaining optimum performance at all times.

Intuitive perception and response to graphics will make flying easier and safer

Intuitive perception and response to graphics will make flying easier and safer

The airplane’s human-machine interface (HMI) will enable a pilot to “fully utilize the benefits” of the on-board systems, while adding to the safety of operation.  Tine Tomazic is leader of the American Society for Testing and Materials International (ASTM) team creating standards for such interfaces.  He noted that “Nobody likes to contribute to standards – but likes it when they’re done.”  This HMI will be a first for hybrid aircraft, and is being designed “To elevate safety and improve user experience.”

Color and perception play a big part in the visual ergonomics and pilot recognition of different situations, both safe and of concern.  Good design here can add to the safety of operation and lower the pilot’s workload.  Hard-to-read avionics can increase the workload, lead to high cognitive stress, and even a hostile cockpit environment.  Tine is working to replace the glut of text and numbers in displays with standardized icons and to introduce a common layer of infographics.

On a fast track for a complex project, Hypstair could be a seminal aviation event soon

On a fast track for a complex project, Hypstair could be a seminal aviation event soon

Couple the perceptual simplicity of the cockpit with true single-lever power control of the total power train with protections for the engine, motor and batteries, and the pilot can concentrate on flying the airplane. The position of the power handle will directly correspond to the airplane’s power output, an intuitive signal to the pilot. High power depends on the battery charge status, for instance, and the system will reduce the rate of power after a set time to reduce high discharge rates, although the pilot can enable overboost to overcome potentially dangerous situations.

With significant advances in structure, powerplant design, ergonomics and human factors, the Hypstair will be more than just a speedy, great-looking airplane.  It may mark the beginning of new ways of integrating the aircraft, pilot and systems into a new and unified whole.

As for a question about the electric version of the Alpha Trainer announced at least year’s EAS, Tine left the audience with a twist of wry: “Development goes at the speed of cash.”



Two Ultralights Promoting Electric Power

Several electric aircraft graced the flight lines and display tents at Oshkosh this year, while several that had flown in previous years stayed home.  It shows a growing market segment – one apt to continue growing as batteries and components improve.  The ultralight area showed the greatest number of new developments, with two aircraft showing how one might achieve battery-powered flight on a budget.

Chip Erwin and the Aviad MG-12 Zigolo

Several have noted the Aviad MG-12 “ Zigolo” (named after a small bird – not as some surmise, a “gigolo”) from Italy has the look of a Mike Sandlin Basic Ultralight Glider, although it also has elements of other early Part 103 machines and carries a complete aircraft kit price of $14,500.  “Complete” includes a two-stroke, single cylinder Vittorazi Moster 185-cc engine.  $1,500 adds a more advanced BRS ballistic recovery parachute, and another $1,500 nets a more complete, more quickly finished kit.  Aviad claims the basic kit takes only 100 hours to complete, so a more finished option would be nearly ready to fly.

MG-12 Zigolo ready to fly - as it did several times during AirVenture

MG-12 Zigolo ready to fly – as it did several times during AirVenture

Imported by Chip Erwin, it is one of a stable of three aircraft, each with a specialized mission: besides the MG-12, Erwin fields the Mermaid LSA amphibian and the SC3D LSA – both made in China.  The Zigolo, though, is intended as  a low-cost way to enter sport flying.

As shown in the video, Zigolo flies like an ultralight, and seems to be very stable and a great platform on which to enjoy the open air and the scenery below.  Pilots are protected by the surrounding structure; an impact skid under the pilot’s seat protects against heavy landings and a Comelli pneumatically-actuated ballistic parachute allows a gentle let-down if things truly get out of hand. A simple twist throttle on the control stick modulates the engine’s or motor’s speed, simplifying control and giving a flying motorcycle feel to the proceedings.

An electric motor option under development will add to the overall cost, but the complete airplane will still be priced well under $25,000.  The Agni motor shown at Oshkosh is no longer available through Electravia, Anne Lavrand limiting her business these days to supplying her popular e-Props.  One can still buy a Lynch or Agni motor (virtually the same motor made in different countries) from various suppliers, and find an appropriate controller and batteries for a true do-it-yourself adventure.  One can also look through the options becoming increasingly available, including one on display in the Zigolo tent.

Don Linebacker's concept motor.  The shaft running through the motor's core slides in and out, pivoting the   mounts for the propeller blades and providing variable pitch

Don Linebacker’s concept motor. The shaft running through the motor’s core slides in and out, pivoting the mounts for the propeller blades and providing variable pitch

Donald Lineback, the motor’s designer, hopes to power many different craft with his creation, suitable for a single push or pull propeller configuration, twin or hybrid. The motor package will include the I. C. E. (Internally-Cooled-Electric) Motor, “A true outrunner with a motor controller,” a smart battery with built-in protection and the claimed lowest available weight-to-Amp-hours ratio; a smart charger which can connect to a generator or AC outlet, and a propeller designed for the pitch adjustment capabilities of the motor.

Now under evaluation to determine its production cost, the axial-flux motor runs at maximum efficiency at any RPM, according to Don.  New lithium air (LiO2) batteries are claimed to deliver three times the power of lithium-ion cells, and Don is investigating that claim.

He notes that, “While [overall] airplane sales were scarce at the show – we found nearly 200 people interested in the potential for electric flight.”

Brian Carpenter and the EMG-6

Brian has been developing the EMG-6 for over two years, building a machine that uses wing and tail components from Quicksilver and a purpose-built fuselage that houses the first of probably several electric motors.  He does all the prototyping at his Corning, California hangar and has come up with unique methods of hand-crafting carbon-fiber fairings, extruded foam gap seals, and battery packs fitted to the contours of the passenger seatback.

Simple configuration with basic fairings.  Builders should familiarize themselves with different regulations regarding different forms of the machine

Simple configuration with basic fairings. Builders should familiarize themselves with different regulations regarding different forms of the machine

Showing videos of his 55th and 56th test flights, Brian drew appreciable and appreciative crowds to presentations in the Honda Forum tents. A constantly changing crowd in the ultralight area viewed the machine, with the motor, controller and battery packs on a table near the two prototypes on display highlighting the light weight and compact nature of the sustainer power system.

Adventure Aircraft sells the basic kit requiring some fabrication and welding for $12,000 and a fast-build kit requiring only assembly for $16,000.  Either provides a low-cost entrée to ultralight, Experimental Amateur Built (EAB) gliding, but neither includes a power system.  As with the MG-12, the EMG-6 would require only about 100 hours to complete a ready-to-fly aircraft.  As Brian finishes work on the power system, those components will become available.

In the meantime, builders wanting to get a head start can download plans  on a subscription basis and rent building jigs for the welded parts of the fuselage to simplify even the most labor-intense approach to getting a completed machine.  Brian claims, “Between 25% to 40% of the aircraft’s total cost could be saved depending on your capability.”

The builder can start construction with “a minimal cost outlay,” and under one plan, purchase components individually or as complete subassembly kits “depending on budgetary constraints.”

EMG-6 battery stack can be as desired - as long as it fits within weight and balance limits

EMG-6 battery stack can be as desired – as long as it fits within weight and balance limits

With machines on the field powered by a variety of electric powerplants and possessing a wide range of sophistication and performance, AirVenture 2014 offered a world of electric flight possibilities.


JoeBen Bevirt, founder and CEO of Joby Aviation, Joby Motors, and related enterprises, has thought long and hard about the financial costs and lost productivity brought about by the daily automotive commute, a 1.6 hour per day ordeal for many in our urban centers.  JoeBen and the Atlantic magazine agree that commuters squander 5.5 billion hours and 2.9 billion gallons of fuel annually, stuck in the fitful despair of slow or unmoving traffic, sharing only frustration and polluted air with their fellow motorists.

JoeBen told attendees at the April Electric Aircraft Symposium that several years before, he had the seeming pipe dream of moving people by air in a single-seat, eight-motorm, vertical takeoff and landing, electric commuter aircraft that would take one 100 miles at 100 miles per hour for one dollar.  The combination of Greg Cole’s Sparrowhawk and electric power focused too much on efficiency, according to JoeBen, and battery technology had not evolved to allow the practical outcome to this dream.  With 250 Watt-hour-per-kilogram batteries now a reality, though, JoeBen thinks he can make some magic, creating a two-seat, 12 pivoting motor craft that could carry two people 200 miles at 200 mph for $20.

As explained on Joby’s web site, “This environmentally-friendly personal airplane requires 5 times less energy than conventional auto transportation at 5 times the door-to-door speed.”  The combination of speed and economy would make this a highly attractive alternative to the daily grind on the ground.

The systems seem more complex than the original Monarch, with 12 motors pivoting individually instead of being mounted to one pivoting wing. In “active development,” the S2 has garnered one of Popular Science’s Invention Awards for 2014, with the magazine listing the potential merits of the design.

“Supercomputer simulations of a full-scale, 1,700-pound S2 suggest it could fly two people about 200 miles (New York City to Boston) in an hour on 50 kilowatt-hours of electricity, or roughly equivalent to 1.5 gallons of fuel used by a typical two-seat airplane—which would make the new aircraft about five times more efficient.”  They add, “Computers adjust motor speed 4,000 times per second to optimize efficiency, reduce noise, and improve flight control.”

In cruise mode, the S2 would take two passengers at 200 mph to their selected destination (Joby Aviation)

In cruise mode, the S2 would take two passengers at 200 mph to their selected destination (Joby Aviation)

Many of the ideas for this aircraft were tested on a three-propeller machine flown above Joby’s Santa Cruz, California development site.  Another outcome of this testing is the Lotus, a long-endurance unmanned aerial vehicle (UAV) inspired by Mark Moore’s Samara.

The split wingtip can add span length and lower wing and span loading when fixed in forward flight, but can turn into an upward-facing rotor blade when powered.  The neat aerodynamic, robotic and power transition tricks involved can be found in the technical paper by JoeBen, Edward V. Stilson, Pranay Sinha, and lead author Alex M. Stoll, who showed much of the technology to your editor at last year’s AirVenture.

Finally, Leap Tech, also developed in conjunction with NASA, has 16 to 20 motors distributed along the leading edge (through varying artist concepts) of its high-aspect-ratio wing, with wide-bladed propeller blades sweeping most of the wing area, and high-lift flaps enabling a coefficient of lift greater than 5 for takeoffs and landings.  Even though the combined motors might not exceed 300 horsepower, the four-seat craft could reach 300 mph and cruise at 200 mph at 12,000 feet. In fact, power required for landing is higher than that required for takeoff, according to the charts in the AIAA paper on the airplane, co-authored by Stoll and Bevirt for Joby, and by Mark D. Moore, William J. Fredericks, and Nicholas K. Borer for NASA Langley Research Center.  This is probably due to the 40° flap deflection for landing compared to 10° for takeoff, and the need to maintain airflow over a more sharply deflected wing.

Mark Moore of NASA and JoeBen Bevirt have collaborated on the LeapTech, a highly-advanced, high-performance four-seater

Mark Moore of NASA and JoeBen Bevirt have collaborated on the LeapTech, a highly-advanced, high-performance four-seater

Computational fluid dynamics (CFD) renderings show the effect distributed thrust has on the wing, allowing only 55 square feet of wing area, compared to 145 square feet compared to a Cirrus SR22.  This gives a wing loading of 55 pounds per square foot, over double that of the Cirrus and similar to WWII fighters.  Its laminar fuselage has about as little wetted area as practicable, further reducing drag.   The high wing loading and sleek shape may work well with higher powered, higher performance derivations of this concept.

JoeBen has also actively been working on motors for more conventional ultralight aircraft.  Mark Beierle of Earthstar Aircraft has a simpler solution to personal flight, his e-Gull 2000 sporting a new 30-kilowatt motor he designed with Thomas Senkel, a German physicist who also participates in development of the e-Volo multi-rotor craft in Germany and redesigned with improvements by JoeBen.  Thomas was the pilot on the company’s first electric multi-rotor machine, proof-of-concept VC-1, balancing atop a “yoga ball” and spinning up the 16 rotors to achieve a one-minute, 30-second flight.

Beirele and Senkel first made an 18 kW motor that Mark flew successfully at the Arlington Fly in in 2010, and for several months thereafter.  After 35 hours of testing, however, the motor showed signs of overheating at maximum power.

30 kW Joby motor shown on e-Gull at AirVenture 2014.  Note cooling exhaust fins

30 kW Joby motor shown on e-Gull at AirVenture 2014. Note cooling exhaust fins

A redesigned, 20 kW motor incorporated improved cooling and was able to run for 130 hours and loft the e-Gull to 9,000 feet at full throttle without overheating.  After flying  the airplane at the Arlington, Washington fly in and AirVenture 2013 after installing a 54 hp. Zero Motorcycle motor and battery, Mark took the Senkel motor to JoeBen, who did a complete redesign. The new, 30 kW motor has improved cooling, is able to climb the airplane at around 500 feet per minute, and seems to have all the characteristics which Mark finds desirable.

Joby’s motors are finding multiple uses, with the high number on any one aircraft (except for e-Gulls) pointing toward at least limited mass production.


A Stanford University team of researchers, including Nobel Prize winner and former U. S. Secretary of Energy Steven Chu and Yi Cui, long familiar to CAFE Blog readers, are using carbon nanospheres to coat lithium electrodes and help them resist expansion problems that formerly fractured them, and to keep elements in the battery’s reactive electrolytes from dissolving them.

Dr. Yi Cui in his laboratory.  He has spoken at several Electric Aircraft Symposia

Dr. Yi Cui in his laboratory. He has spoken at several Electric Aircraft Symposia

This approach has enabled the team to craft a pure lithium anode, with all the promise of high energy density that such an electrode holds.   It’s also stable, a boon to longevity for these cells.

As reported in the news release By Andrew Myers for the Stanford Engineering School, “’Of all the materials that one might use in an anode, lithium has the greatest potential. Some call it the Holy Grail,’ said Cui, a professor of Material Science and Engineering and leader of the research team. ‘It is very lightweight and it has the highest energy density. You get more power per volume and weight, leading to lighter, smaller batteries with more power.’”

(The reference to the Holy Grail has led other reports to call the researchers “the knights of nanotechnology” and “the battery barons.”)

The release explains the historical antecedents and the importance of Stanford’s breakthrough.  “All batteries have three basic components: an electrolyte to provide electrons, an anode to discharge those electrons, and a cathode to receive them.

“Today, we say we have lithium batteries, but that is only partly true. What we have are lithium ion batteries. The lithium is in the electrolyte, but not in the anode. An anode of pure lithium would be a huge boost to battery efficiency.”

Guangyuan Zheng, a doctoral candidate in Cui’s lab and first author of the team’s paper in the journal Nature Nanotechnology, explained that the problem was significantly complex enough that many engineers have given up the search for a solution, failing to overcome three major problems in designing the pure lithium electrode.

Deposition process to coat lithium anode with protective sheath

Deposition process to coat lithium anode with protective sheath.  Lower photos show regularity, nano-size of coating

First, lithium ions expand during charging, gathering on the anode, normally made of graphite or silicon.  Because lithium’s expansion during charging is “virtually infinite” compared to the other materials, its swelling and contraction would cause cracks and pits to form. Such breaks in the anode would allow lithium ions to escape, and they would form “hair-like or mossy growths, called dendrites. Dendrites, in turn, short circuit the battery and shorten its life.”  This first challenge is mechanical.

The second challenge is chemical, lithium being highly reactive with the battery’s electrolyte.  It consumes the electrolyte and shortens its usable life.  The third challenge is one of safety.  Several high-profile aircraft and automotive fires have highlighted the concern.

The researchers attacked all three issues by building a protective layer of interconnected carbon domes (nanospheres) resembling a honeycomb on the lithium anode. This “flexible, uniform and non-reactive film… protects the unstable lithium from the drawbacks that have made it such a challenge. The carbon nanosphere wall is just 20 nanometers thick. It would take some 5,000 layers stacked one atop another to equal the width of single human hair.”

“’The ideal protective layer for a lithium metal anode needs to be chemically stable to protect against the chemical reactions with the electrolyte and mechanically strong to withstand the expansion of the lithium during charge,’ Cui said.”

Stanford’s nanosphere layer, composed of amorphous carbon, is chemically stable, and is strong and flexible enough to conform to the lithium as it expands and contracts during the battery’s normal charge-discharge cycle.  So far, the team has demonstrated 99 percent Coulombic efficiency (the ratio of battery output to current input on charging) after 150 cycles.  Unprotected lithium metal anodes have managed 96 percent, taking them out of contention for commercial viability.

Dr, Cui explains, “The difference between 99 percent and 96 percent, in battery terms, is huge. So, while we’re not quite to that 99.9 percent threshold, where we need to be, we’re close and this is a significant improvement over any previous design. With some additional engineering and new electrolytes, we believe we can realize a practical and stable lithium metal anode that could power the next generation of rechargeable batteries.”

The abstract for Stanford’s Nature Nanotechnology offering provides additional insights:

For future applications in portable electronics, electric vehicles and grid storage, batteries with higher energy storage density than existing lithium ion batteries need to be developed. Recent efforts in this direction have focused on high-capacity electrode materials such as lithium metal, silicon and tin as anodes, and sulphur and oxygen as cathodes. Lithium metal would be the optimal choice as an anode material, because it has the highest specific capacity (3,860 mAh g–1) and the lowest anode potential of all. However, the lithium anode forms dendritic and mossy metal deposits, leading to serious safety concerns and low Coulombic efficiency during charge/discharge cycles. Although advanced characterization techniques have helped shed light on the lithium growth process, effective strategies to improve lithium metal anode cycling remain elusive. Here, we show that coating the lithium metal anode with a monolayer of interconnected amorphous hollow carbon nanospheres helps isolate the lithium metal depositions and facilitates the formation of a stable solid electrolyte interphase. We show that lithium dendrites do not form up to a practical current density of 1 mA cm–2. The Coulombic efficiency improves to 99% for more than 150 cycles. This is significantly better than the bare unmodified samples, which usually show rapid Coulombic efficiency decay in fewer than 100 cycles. Our results indicate that nanoscale interfacial engineering could be a promising strategy to tackle the intrinsic problems of lithium metal anodes.


PADA Lectures Highlight Innovation

The 2014 Personal Aircraft Design Academy (PADA) dinner and awards ceremony, the latter held in the Vette Theater at the Experimental Aircraft Association’s Museum, highlighted design innovation and the possible commercial exploitation of new technology. 

Dr. Brien Seeley, Founder and President of the CAFE Foundation, hosted the evening and introduced your CAFE blog editor, who gave an overview of innovations in aircraft, avionics and powerplants he’d encountered on his daily hikes around Wittman Field.

Dr. Seeley had the honor of presenting this year’s PADA trophy to John O’Leary, Vice President and General Manager of Airbus Americas Engineering (AAE), for the parent company’s development of the E-Fan, a twin-motored personal airplane that has been a highlight of the Paris and Farnborough air shows.  With the flying displays behind it, the proof-of-concept machine will be the basis for two-seat (E-Fan 2.0) and four-seat (4.0) production variants that will bring smooth electric power to private flight.  The two-seater, which can double as a training vehicle, will be in production by the end of 2017.  The larger 4.0 would be introduced two years later.

Airbus VP George O'Leary  holds PADA trophy, designed and crafted by Dr Seeley and son Tim

Airbus VP George O’Leary holds PADA trophy, designed and crafted in wood, metal and stone by Dr Seeley and son Tim

The two-seat E-Fan 2.0 and four-seat 4.0 aircraft will be produced by a new Airbus subsidiary, VoltAir, in a new factory at Bordeaux’s Merignac airport in France. Airbus Group Innovations is developing a “range extender,” a kerosene-fueled generator to charge batteries in flight on the 4.0  and potentially extend endurance by as much as 1.5 hours.

Airbus “believes aircraft prices will be competitive with similar-sized piston-engined aircraft. Operating costs are targeted at one-third of traditional piston-engine light aircraft, with a ground-based charging unit able to bring the aircraft back to full endurance in just 1.5 hours.”

E-Fan 2.0 and 4.0 will have fixed gear, prices competitive with existing aircraft, and twin electric power

E-Fan 2.0 and 4.0 will have fixed gear, prices competitive with existing aircraft, and twin electric power

As reported by Torkell Saetervadet, Executive Editor for the Norwegian magazine Fynytt, O’Leary noted, “Airbus is a fantastic company, but we are also a great company. In a project like this, it is convenient to work with a more compact organization. Therefore, we as recently as a few days ago established the wholly owned subsidiary Voltaire to develop and market the aircraft.”  Gilles Rosenberger and Aerodev will undertake industrial design for the facility and for the manufacturing processes involved with the new aircraft.

O’Leary explained that Airbus will, besides the Bordeaux plant, rely on Powerhouse, a facility near Munich that will develop electric propulsion systems in “close cooperation” with Siemens.

The new aircraft could include electronic control touchpads and morphing wings and control surfaces that would do away with traditional hinged surfaces.

The importance of this award can be measured by the achievements of past award winners.

  • 2003: Dr. Bruce Holmes
  • 2004: Dick VanGrunsven
  • 2005: Werner Pfenninger
  • 2006: Alan Klapmeier
  • 2007: Jerry Gregorek
  • 2008: John Roncz
  • 2009: Burt Rutan
  • 2010: Greg Cole
  • 2011: Barnaby Wainfan
  • 2012: Tine Tomazic
  • 2013: John Sharp

The awards ceremony, highlighted by a trophy designed and crafted by Dr. Seeley and his son Tim, was followed by two detailed presentations on highly innovative new designs.

Oliver Garrow presented the technical details of a new tilt-wing VTOL aircraft—the Elytron.  The fourth iteration of a long-term effort to produce a practical machine that is simpler and better performing on less power than a helicopter, Elytron was on display all week in the Innovation Center as a two-seat, full-size display.  Its pivoting central wing is key to its ability to rise and descend vertically, and according to Oliver, is simple to fly and control.

Oliver Garrow shows the multiple lifting surfaces of his VTOL Elytre

Oliver Garrow shows the multiple lifting surfaces of his VTOL Elytre

Oliver has flown the three preceding generations of craft, in radio-controlled form, on the field at NASA Ames Research Center in Mountain View, California.   The Elytre is both an extension of those designs and a significant change.

Oliver explained the cost breakdown for the original powerplant concept that would have cost over $180,000, with dual YASA motors, engines, generators and batteries.  The final choice of a Suzuki/Habayusa 1.4-liter unit may be a bit controversial, but it is less expensive at under $25,000.  Gearing and power transfer to the large dual propellers should be a daunting task.

With a pivoting main wing and all else retaining its position throughout flight, the aircraft may achieve the simplicity of flight that Garrow seeks to achieve.

Richard Hogan from Commutercraft presented “The Innovator—a New 3-surface Aircraft,” the prototype of which was on display all week near the Homebuilders Hangar.  Richard emphasized that despite folding wings and electric wheel motors, the Innovator is a roadable airplane – not a flying car.  The 120 pounds of batteries and a ground tractable landing gear enable the pilot to “drive” the compact airplane home to a safe spot in the carport or driveway.  It is not meant to take long trips on the ground, but to simplify trips to the airport (no car to park), reduce costs for hangars and make aircraft ownership far more convenient.  It’s a head-smacking (why didn’t we think of that?) elegant solution to an age-old pilot problem.

Richard Homan discusses the benefits of his three-surface flyer

Richard Homan discusses the benefits of his three-surface flyer

The three-surface configuration certainly drew crowds throughout the week, and the tight installation of all components evoked a bit of wonder at the careful planning that went into the Innovator’s construction.  Despite that, Richard assured all that 250-pound Americans would have no trouble fitting, nor would they disturb the center of gravity or payload limits.  The airplane is promised to have excellent performance, handling , range and comfort.

The Prize award, two exceptional lectures on exciting new aircraft, and the opportunity to gain insight into creative minds hard at work – what more could one ask as part of truly experimental aviation?


Chip Yates’ Records Ratified by FAI

With recognition this week of five electric airplane records set by Chip Yates in flights last year, the Fédération Aéronautique Internationale (FAI) and the National Aeronautic Association (NAA) ratified performance numbers that top those of most single-engine high-performance gasoline-powered aircraft from established manufacturers, according to Yates. 

Chip Yates relaxes with Long-ESA at Mojave Air Show

Chip Yates relaxes with Long-ESA at Mojave Air Show

Your editor was on hand for the California Capital Airshow last October to see Chip take his Long-ESA to 500 meters (1,640 feet) from a standing start in only 62.58 seconds, 17 seconds faster than the previous record set by a fossil-fuel burner.

The new records were really set last year between September and November and have just been ratified. They include an altitude of 4,481 meters (14,701 feet), a time to climb to 3,000 meters (9,840 feet) of five minutes, 32 seconds, and maintaining an altitude of 4,439 meters (14,564 feet) in horizontal flight.  Chip achieved two speed records, reaching an average of 324.02 kilometers per hour (201 mph) in four passes over a three kilometer (1.86 mile) course; and averaged 225.88 kilometers per hour (140 mph) in two passes over a 15 kilometer (9.3 mile) course.

Chip sees these achievements as helping overcome the image problem with which electric vehicles have long contended.  His press release explains, “’With these records, we are continuing to show the world that electric vehicles don’t have to be slow and boring,’ said founder (of Yates Electrospace Corporation) and test pilot Chip Yates, who also holds ten world records with the World’s Fastest Electric Motorcycle.  ‘No one imagined just a few years ago that a plane powered by nothing but batteries could go 220 miles per hour and out climb Cessnas and Pipers and those kind of long-standing gasoline airplanes!’”

His Long-ESA’s take-off weight of 1,540 pounds includes Chip, and puts the airplane into the FAI’s “C-1b Group VI” class: Electric Land Airplanes weighing 1,102-2,205 pounds.

Of the five world records, the most surprising, according to Chip, is the “Time to Climb to a Height of 3,000 Meters” result of 5 minutes and 32 seconds, selected by the NAA as the “Most Memorable Aviation Record of 2013.”  The press release explains, “From a dead stop on the runway to the acceleration, take-off and climb to 9,843 feet above ground level (3,000 meters), the electric airplane made use of its 258 horsepower and 400 foot-pounds of torque to produce a sustained climb rate of 2,000 feet-per-minute, which beats the published specifications of any gasoline piston single airplane currently for sale.”

He teamed with Red, a maker of high-definition digital video cameras, to create a stunning record of his record attempts.  We can only hope the full-length version shows up in IMAX theaters sometime soon.

Chip’s Long-ESA uses UQM Technologies’ high-performance electric motor (which also powered his motorcycle), “which does not require oxygen and, in conjunction with an EnerDel advanced lithium-ion battery pack, has demonstrated constant power at 93% thermal efficiency from the ground all the way to 15,000 feet in flight testing to date.  The aircraft is capable of regenerating electrical power during descents with an on-board kinetic energy recovery system (‘KERS’).”

Comparing his Long-ESA with the e-Fan from Airbus Industries, Chip notes his machine has three times the power, is much faster and demonstrates greater performance in all aspects.  He makes the comparison based on the fact that, “We did it all with volunteers and ZERO outside money!  His pride in his all-American, free-enterprise campaign is readily apparent.

Testing at China Lake Naval Air Station showed the U. S. Navy that electric aircraft have low heat and radar signatures. They’ve signed a joint research and development contract (NCRADA-NAWCWDCL-13-246) with Yates Electrospace Corporation to advance the company’s hybrid-electric stealth UAV design known as Silent Arrow™.

Chip’s team continues to work on their mid-air recharging approach, with demonstrations planned in late 2014 or early 2015.  Successful tests will lead to Chip’s attempt at duplicating Charles Lindbergh’s 1927 flight using aerial recharging to help him cross 3,600 miles of Atlantic Ocean.

Named a “Pioneer of Aviation” by the State of California, Chip holds more than 10 patents and a Master’s Degree from the University of Southern California.

A “passionate advocate for Science, Technology, Engineering, and Math (STEM) education and outreach, [Chip} was recently named the National Spokesman for the Conrad Foundation, which celebrates the life and entrepreneurial spirit of astronaut Pete Conrad, the third man to walk on the moon.  He also recently launched to promote his STEM speaking tour to schools, and is writing a book to encourage kids to overcome adversity in pursuit of their dreams entitled ‘The Hoodlum Diaries’ due out in 2015.”

Chip Yates and Long-ESA are probably destined for more records and further investigations of the limits of what can be achieved with electric aircraft.