Happy Velis Electro News from Pipistrel

Taja Boscarol, Public Relations Manager for Pipistel Vertical Solutions, and Michael Coates, Master Distributor for USA, Australia & New Zealand, shared a lot of happy news this week about their Velis Electro.

Electric Outsells Gasoline Powered

Michael puts his news in enthusiastic, all-caps context.  “The US has a new president, Europe is under siege from new Covid varieties, and Pipistrel is adding a SECOND SHIFT TO KEEP UP WITH PRODUCTION!

“Did you know that in 2020 Pipistrel DELIVERED 111 (one-hundred and eleven) of the certified Pipistrel Velis electric aircraft, as well as many more Pipistrel ALPHA Electro aircraft?  In fact, this year for the first time ever, Pipistrel produced more electric aircraft than gasoline powered!”

Pipistrel’s Velis Electro is becoming a popular trainer, especially where quiet operation is a must

More than 70 Pipistrel Velis aircraft are already on 2021’s order books, with many more anticipated through the remaining 11 months of the year.

The second shift essentially means doubling production, and this of course leads to increased demand from suppliers.  Michael adds, “Pipistrel is cooperating with dozens of OEM manufacturers, implementing Pipistrel electric propulsion into their fleets.

“The future really looks good for electric aircraft and the Pipistrel Velis, which is going from strength to strength in both sales and use.”

Mechanics Need Training

Taja Boscarol has two related news items.  With many electric aircraft coming into play, it’s only natural that there will be a big need for newly-trained mechanics for the new technology.  Taja announces, “We are happy to let you know that Pipistrel organized a maintenance type-training course for Pipistrel Velis Electro, for Part-66 licensed aircraft mechanics.”  (Part 66 is the European Aviation Safety Agency’s set of regulations for aircraft mechanics.)

First-time mechanics might have a hard time convincing themselves that IS the motor

This is an historical first, training mechanics for the maintenance of a certified electrically-powered airplane, the Pipistrel Velis Electro.  Pipistrel can thus train “other organizations’ “Part-66 licensed aircraft mechanics for the purpose of maintenance and repair of our Velis Electro (which is at the moment the only certified fully electric aircraft in the world).”

The five-day course had an enthusiastic reception on its first outing, was repeated, and is now going to be repeated for interested parties.

Taja concludes, “Organizing a training course of this kind is a great achievement and honour for Pipistrel. The road to this point was very long and required cooperation of many individuals and institutions, especially the European Union Aviation Safety Agency and the Slovenian Civil Aviation Agency, who stood by our side during the entire process and gave us their help and support.

“Apart from the two organizations, a great credit also goes to the entire teams of the two companies: Pipistrel Aircraft d.o.o., which is the holder of the authorization, and Pipistrel Vertical Solution, which participated in the entire phase of preparation of manual and training program. The teams showed diligent internal cooperation on every step of the process and contributed to the joint success of the project.”

50 Electric Aircraft for Lease

Taja’s next announcement is straightforward and concise.  “We are happy to announce that in order to accelerate the transition of the aviation to sustainable, zero-emission kind and to enable flight schools and clubs to use electric aircraft without a large initial investment, the French organization Green Aerolease, subsidiary of the W3 group, Pipistrel Aircraft company from Slovenia and with the support of the French Federation of Aeronautics, formed a partnership to offer the first 50 Pipistrel Velis Electro aircraft for rent to French aeroclubs and flight schools, from this season onward.”

Ivo Boscarol, Founder and CEO of Pipistrel Aircraft,adds, “I am delighted to see the confidence given to us by Green Aerolease who decided to commit with us to participate in the reduction of the environmental impact of the aeronautical sector.

Green Aerolease can find the use of electric aircraft rewarding.  Europe has over 100 small airports with “severe flight restrictions,” or where flight patterns don’t allow training circuits because of noise.  Pipistrel’s Velis Electro emits only 60 dB of noise, making it welcome at many otherwise touchy venues.  The 50 Velis Elctros headed for France will bring many operations back from the brink, and expansion to 200 trainers in the next three years will encourage further operations in other EU countries.

Charles Cabillic, Founder of W3 and Green Aerolease, said: “We are particularly proud to make this partnership with Pipistrel Aircraft, pioneer of breakthrough innovation in the light aviation sector.”  Velis Electros have demonstrated over 200 hours of reliable service, and enabled next steps into a future of “green aviation.”

“I am convinced that the aeronautical sector has a great future, with the progressive arrival within two to three years, of light electric or hybrid aircraft designed for business travel or leisure aviation, because it will permit to revive the French aviation.”  Let’s hope we can celebrate the same spirit in America soon.


Michael Friend’s Spark Solo

“The Quest for a Truly Practical Electric Touring Motor-Glider”

Mike Friend is not your typical retired aircraft executive.  As Technical Director for Boeing, he oversaw “the first manned fixed wing aircraft powered by a hydrogen fuel cell/lithium ion battery powerplant that first flew back in 2008.”  He’s been associated with green energy projects since then, including work on the Boeing-supported Zunum project, a set of 10- to 50-passenger electric hybrid airliners.  On the personal front, he hopes to design and build the Spark Solo, a single-seat electric motorglider that will enable cross-country flights from his home base of Bremerton (Washington) Regional Airport.

Spark Solo in rendering by Shawn Cvetezar depicting a good soaring day

Working with Gabriel DeVault

Motorgliders make a good combination with battery power.  Their clean lines enable using low power at cruise, and as this video from Gabriel DeVault shows, even a respectable takeoff and climb with power limited to 25 kilowatts (33.5 horsepower) in this instance.

Normally, DeVault’s Sonex would make full use of its Zero Motorcycle motor’s full 52 kilowatts (69.7 horsepower), but this self-limited output puts into perspective the importance a long wingspan’s low span loading.  Being able to fly safely in “econo-mode” would allow longer flights by limiting the battery drain during takeoff.

Shawn Cvetezar rendering shows general layout of motor, batteries. Spark Solo upholds Mike’s support of Stelio Frati’s dictum about beautiful airplanes

Mike was lucky enough to meet Gabriel on one of his outings, and that might have led to his choosing a Zero Motorcycle motor for his projected bird.  Financial considerations play a part, too, with Pipistrel’s 40 kilowatt package, batteries and all, totaling $27,000.  Wrecked Zero Motorcycles can be found for $9,000 or less, giving a prospective builder motor, controller, batteries and even cabling and instrumentation.  The only extra needed is a propeller speed reducer, a simple item designed by Mark Beirele for his Zero-powered eGull.

The Airplane’s Design

 Mike is a self-admitted “fan” of “touring motor-gliders,” machines capable of self-launching and as implied – touring to distant places.  He particularly likes the Schleicher ASK-14, a German craft that used the wings and tail surfaces from the popular KA-6 sailplane.  It used a raspy little four-cylinder Hirth two-stroke engine, which thankfully went silent in soaring mode.  The engine didn’t have an electric starter, so the pilot had to yank on a pull-cord if he or she wanted to relight the motive power.  Two-strokes being what they are, the engine sometimes balked, and forced a landing.  That is what makes electric motors so ideal for self-launching sailplanes or touring motor gliders.  They rarely refuse to go when requested.

Mike has a set of requirements for the craft.  They start with having enough space inside to accommodate a 6-foot, 2-inch person like Mike.  It should allow single-person operation – enabling rigging and de-rigging, and all operations by the owner/operator alone.  One of the off-putting aspects of sailplane operation is the large crew required to assemble, launch and retrieve an airplane.  This would allow flights when the owner desired with no need to coordinate with others.

Practicality reigns in most respects for the Spark Solo.  It can be kept in a standard hangar and operated from a 1,500-foot grass strip.  It will meet FAA glider requirements for maximum weight/wing span squared of less than 3.0 Kg per meter squared, (0.62 pounds per foot squared).  Spark Solo will be registered as an FAA Experimental Amateur-built Glider – Self Launching.

The light wing and span loading will enable an initial rate of climb of at least 1,000 feet per minute, and the electric motor will produce quiet operation.

Base Spark Solo uses Pipistrel wings, tail, Zero motor, controller and batteries. Proposed flight would require recharging at KORS

Mike is adamant that, “The appearance of the aircraft shall comply with the dictates of my hero, Italian aircraft designer Stelio Frati who is rumored to have said – ‘There is no use for an ugly aircraft when a few minutes of thought will produce a beautiful one.’”

Mike is using the wings and tail section from a Pipistrel Sinus Flex, but it would seem that many other standard-class size flight surfaces would work, although they would take different approaches for their assembly into a completed airframe.  Wings and Wheels has on-line classifieds for used gliders and parts.

Economy of Operation

 Time and money are often conflated, and a small airplane can save time at a usually high cost.  Electric aviation may help with that equation, however.  The shortest car trip from Bremerton to Orcas Island, according to Google Maps, runs 118 miles on the most direct route and requires passage over one toll road and a ferry trip.  The fastest automotive passage runs 167 miles, runs north on I-5, and still has toll roads and a ferry trip.  Either takes about four hours.  On the Anacortes to Orcas Island ferry, fees run from $14.50 for a single adult to $34.50 for a compact car and driver and $44.50 for a vehicle under 22 feet and its driver.

Alternative configuration would employ e-Genius approach, probably require different motor from base configuration

Considering an average of $3.00 per gallon for automotive gas, and an average of 25 miles per gallon, a car would use a little over $28 worth of gasoline for the shorter trip and just over $40 for the longer route.  It’s impossible to avoid a ferry trip to the island, for a another $69 for the round trip.  Even Mike’s Aeronca Champion, average 5 gallons an hour, would take about an hour to make the trip and a round trip would consume about $55 in avgas.  In the Spark Solo, with electricity costing about 9 cents per kilowatt hour in Washington (among the lowest rates in the world), the trip would cost around $3.14 for the round trip.

A more shocking comparison comes from looking at charter aircraft rates for the 73 mile trip from KPWT to KORS.  The trip for a single passenger in a chartered Cessna 172 is $1,264.  The price for “premium air charter” in a Cirrus SR22 climbs to $3,828!

See the chart below for Mike’s calculations based on energy usage for this clean single-seater.

Spark Solo Energy Usage – KPWT to KORS and return
Mission Phase Power  Duration Energy Used This Segment Total Mission Energy
(kW) (Hours) (kW-hrs) (kW-hrs)
Taxi from hangar to end of runway at KPWT 5 0.1 0.5 0.05
Takeoff and climb to 500 feet 40 0.017 0.68 0.73
Climb from 500 feet to 2000 feet 30 0.25 7.5 8.23
Cruise at 70 Knots – 73 Nautical miles 8 1.04 8.32 16.55
Descent and Landing 1 0.15 0.15 16.7
Taxi to parking at KORS 5 0.1 0.5 17.2
Taxi from parking to runway at KORS 5 0.1 0.5 17.7
Takeoff and climb to 500 feet 40 0.017 0.68 18.38
Climb from 500 feet to 2000 feet 30 0.25 7.5 25.88
Cruise at 70 Knots – 73 Nautical miles 8 1.04 8.32 34.2
Descent and Landing 1 0.15 0.15 34.35
Taxi to parking at KPWT 5 0.1 0.5 34.85
NOTE: cruise power based on scaled Pipistrel Taurus data, maximum takeoff power limited to 1 mile

Mike is currently working on articles about this promising aircraft.  For the time being, we can see that a well-designed motor-glider can promise grand adventures and reasonable operating costs.


Stemme Goes Electric with its New Elfin

Reiner Stemme designed his namesake sailplane 30 years ago and the overall design and his new Elfin retains the original pop-out nose cone, folding propeller configuration.  The 50:1 glide ratio means this 20-meter (75-foot) span motorglider offers less than 40 pounds of drag at its maximum takeoff weight 0f 1984 pounds.  That is a significant benefit for the new electrically-powered version – which can fly further and save its batteries for retrieval and go-arounds.

In its latest iteration, the Stemme configuration is a totally new airframe being built by a totally new company, Reiner Stemme Aero GmbH.  As explained on the new firm’s web site, “The Elfin design is a complete new development and [is] not base[d] upon the existing S10.  REINERSTEMME.aero GmbH, the present company of Dr. Reiner Stemme, is not connected to STEMME AG.”

A High-Flying Heritage

Earlier Stemme designs have accomplished much in the way of efficient, high-performance flight.  In 2014, Klauss Ohlman accomplished one trans-continental trip from Europe to Asia, followed by the surmounting of Mount Everest in an SV-10T.

That accomplishment is recounted even in the new company’s web site. “A highlight in its history was the successful mission “On Top of the World” in the Himalaya region using an underwing 3D camera system from DLR. We have the ambitious objective to continue this story in a new generation of planes; therein we rely on radical innovations. We cooperate with German research institutes and the industry – so we can best incorporate today’s knowledge in this project.”

New Name, New Propulsion

The REINER STEMME elfin 20.e name represents the 20-meter (75-foot) wing and its electric (e) power system.  A further refinement, the “ex,” has a range extender that will allow flights up to six hours and 1,000 kilometers (540 miles) under power.

Elfin’s battery system, with 21 kilowatt-hours nominal value can provide a flight profile that uses four kWh for three minutes of taxiing and a take-off and climb to 500 meters (1,600 feet).  It could then, on the same charge, fly level for an hour at 130 kilometers per hour (70 knots or 80.5 mph) on another 12 kWh.  70 knots is Elfin’s best glide ratio.  A climb to 3,000 meters (10,000 feet) would require 16 kWh.

Nose-mounted Siemens motor simplifies power train of gas-powered Stemmes, eliminating propeller shaft that ran through cockpit

The liquid-cooled Siemens motor can produce 72 kW peak (96.5 hp) and 55 kW continuous (73.75 hp).  Two 60-kilogram (132-pound) 600 Volt battery packs of three modules each sit behind the cockpit.  Stemme expects 1,000 full cycles from the packs, which can be replaced at a cost of 18,000 euros ($21,700).  With at least 1,000 hours of flight from each cycle, and more in soaring mode, cost of operations would be under $20.00 per hour.

Elfin range extender allows up to 1,000 kilometer flights under power

For those wanting a longer mission profile, the Elfin can be fitted with an auxiliary range extender. The 60 kilogram (132 pound) under-wing mounted internal combustion engine and generator setup can deliver 30-35 kW continuously.  At a normal cruise of 185 km/hr (100 knots or 115 mph) at 10,000 feet, the Elfin can carry its two passengers 1,000 kilometers, or 540 nautical miles – roughly six hours endurance.  Fuel is carried in the center wing and the pod carrying the engine/generator can be mounted or demounted by a single person with a “rigging aid.”  In operation, a single on/off switch enables or disables the range extender.

Comfort and Safety

Pilot and passenger share a wide side-by-side cockpit in front of the wing.  A centrally-mounted instrument cluster and single-lever power control makes operation simple.  A directly-coupled Siemens motor in the fuselage nose turns the folding propeller which neatly tucks in behind a retractable nose cone.  (Current versions use a manual extension/retraction handle, but Stemme says the electric version has automatic operation.)  Your editor has been astounded at how easily the small-diameter prop pulls a large Stemme into the air.

Reiner Stemme has designed a “specific wing airfoil 20e-143 without premature lift plateau, seamlessly optimized over the entire wing span.”  Their long center section, fixed to the fuselage, avoids the problem of separate wings which plug in and have to be taped along their chord to avoid extra drag.  What the company describes as an “ambitious wing-to-fuselage-intersection design with fillets for drag reduction” is meant to overcome at least some of the drag from aerodynamic interference between joining components.  Outer wing sections pivot and allow the large craft to be stored in a conventional hangar.

If all were to go wrong (an unlikely event) the Elfin can be lowered safely be a whole-airplane ballistic parachute.  As an indication that authorities are betting that won’t happen, Elfin can be certified under EASA (European Aviation Safety Administration) or FAA equivalent rules.

We look forward to seeing this latest example of Reiner Stemme’s creativity in the air soon.


Archer Aviation Gets Fiat Chrysler Backing

Another eVTOL?  Among the many battery- and solar-powered entries at this year’s (virtual) Consumer Electronics Show, Archer Aviation has entered the electric Vertical Takeoff and Landing (EVTOL) market with Fiat Chrysler backing.  It’s being discreet about it, however, and reveals little detail.

The company willingly shares its mission statement, though.  “To fix traffic and create a fully renewable transportation solution, we’re designing, manufacturing, and operating advanced electric aircraft that can travel 60 miles at 150 mph, all with today’s technology.”

They present only one picture of their design, a head-on shot on a black backdrop.  We can see the six large rotors blanketing the leading edge of the wing, but wonder how and where the six vertical lift rotors are hiding.

Most used image gives “glamor shot” approach used in high-end car ads, but provides little detail

eVTOL Insights provides more information on the planned craft’s specifications:

  • Aircraft type: eVTOL
  • Piloting: Will be piloted in the beginning and will have autonomous capability in the future
  • Capacity: 4
  • Cruise speed: 150 mph (241 km/h)
  • Range: 60 miles (nearly 100 km)
  • Propellers: 12
  • Maximum takeoff weight: 7,000 lbs (3,175 kg)
  • Windows: Panoramic window spectacular views
  • Wing: High wing
  • Tail: V-tail
  • Safety features: Distributed Electric Propulsion (DEP), provides safety through redundancy for its passengers and/or cargo. DEP means having multiple propellers and motors on the aircraft so if one or more motors or propellers fail, the other working motors and propellers can safely land the aircraft. In addition, the company is increasing the safety of their aircraft by eliminating critical parts, increasing component reliability and designing safe aerial batteries.

(Archer’s wording on “eliminating critical parts” might be reconsidered.  Do they mean eliminating unnecessary parts?)

Graphic explains expected performance with math overlay

Big Money Backing

Fiat Chrysler America (FCA) has announced it is investing in Archer.  The partnership should allow Archer to press forward with its plans to have an 80-percent scale test vehicle flying in 2021.  AINonline.com reports, “In a January 12 announcement, FCA, which makes Chrysler, Dodge, Jeep, and Ram vehicles, did not say whether it will actually manufacture Archer’s aircraft. ‘Archer will benefit from FCA’s low-cost supply chain and advanced composite material capability, and design and engineering expertise,”

“A spokesman for Archer told AIN. ‘We have already tapped into FCA’s extensive design expertise, collaborating with the company on elements of the cockpit design of our first full-scale aircraft.’

Benefitting from expertise of Airbus’s A3 Vahana program engineers and designers, co-founders and co-CEOs Brett Adcock and Adam Goldstein have been accused of “poaching” other talent in the area.  The former “headhunters,” having come from the financial talent recruiting firm they built and sold, know how to attract skilled employees.  According to Forbes, the pair, “Have lured dozens of top engineers away from electric air taxi startups like Joby and Boeing-backed Wisk with rich compensation packages that include signing bonuses of two to three times annual salary and talk of connections to deep-pocketed investors.”

One with particularly deep pockets sees a future in the company.  Marc Lore, Walmart’s e-commerce chief and founder of Jet.com, has apparently invested a substantial but undisclosed amount.  (Emulating much of the rest of the program.)

Coming: A Possible Name Change

Piper Aircraft’s Archer has been around since 1976, giving it seniority in the flying world.  It’s understandable then that Piper would sue this new, upstart company for infringing on its federally-registered trademark name.  AIN reports, “In a case filed in the U.S. District Court in Delaware, where California-based Archer was incorporated, Piper alleges that the use of the name for the four-seat, fixed-wing eVTOL infringes its federally-registered trademark and also its legal rights in the state of Florida, where the longstanding general aviation manufacturer is headquartered.”

Archer has yet to name its eVTOL craft, and we hope this kerfuffle over naming rights abates in time for the first flight later this year.


To the Contrary, Propeller-Wise

Sacramento, California based CR Flight is dedicated to building highly-efficient motor/propeller combinations based on contra-rotation – propellers turning contrary to one another.  Not to be confused with counter-rotation – two propellers driven by two different engines and turning in opposite directions – contra-rotating propellers are driven in tandem by the same engine.  In the case of CR Flight, they are driven by the same electric motor.  Their web site shows a simple animation of the result.  An instructive video provides details about the benefits and drawbacks of the concept.


The firm’s mission statement gives a hint of its character.  “CR Flight™ partners with established industry leaders to design, patent, license, manufacture and provide the industry’s only patented counter-rotating motors to UAV/drone commercial and consumer manufacturers and wholesale distributors.  When you see the CR Flight™ name, know that the CR motor™ is manufactured under tight scrutiny for the highest quality.”

Their web site shows their three current offerings, the V-10, V-20 and V-50.  They have V-100 and V-220 models under development.  Model numbers indicate the pounds of thrust produced by the motor/propeller combination, so the V-50 can lift 50 pounds.  With 100 and 220 pounds thrust units on the way, one can see their use on commuter vehicles, ultralight and even Light Sport Aircraft.

CR Flight V-50 provides a rated 50 pounds of thrust from its two contra-rotating propellers according to the firm.  But it can hit 75 pounds with two 45-inch x 13.6-inch pitch propellers

All models now available run on 24 or 48 Volts and relatively low amperages – no more than 131.  Specifications for the V-50 show it develops a maximum thrust of 75 pounds when swinging a pair of 45-inch diameter, 13.6 inch pitch propellers. For a 1,250 gram (2.76 pound) motor, that’s not bad.  It’s putting out 5.52 kilowatts at the point.

Comparing its performance with that of a Hacker motor (a well-regarded electric model aircraft motor) shows the 1,035 gram (2.28 pound) motor’s performance not up to that claimed for the V-50.  Hacker’s Q80-8M V2 has a best output of 5.62 kW with a 24-inch diameter, 10-inch pitch propeller.  Although Hacker doesn’t list thrust, it will doubtless be lower considering the single smaller diameter, lower-pitch prop.

Contra-Rotation is Not New

Even before your editor’s time, “A contra-rotating propeller was patented by F. W. Lanchester in 1907,” according to Wikipedia.  A variety of craft used such propellers through the years, but World War 2 saw the idea come fully into play.

A cold war British bomber intended to track Russian submarines, the Avro Shackleton employed four 37.6-liter Rolls-Royce Griffon engines driving two contra-rotating, 13.6-foot propellers.  Imagine 48 cylinders powering eight propellers.  Several later marks of Spitfires flew with the engine, as well as other British aircraft.

America used contra-rotating propellers on the Northrop XB-35 flying wing, and Russia developed the Tupolev TU-95 intercontinental bomber with 16-foot propellers.  The BBC reports one drawback from those huge props going supersonic at their tips.  “The Tu-95 is considered to be the noisiest aircraft in current service; it’s even claimed that US submarines can hear the aircraft flying high overhead through their sonar domes while still underwater. Western fighter pilots who shepherded Bears over international airspace have reported being able to hear its turboprops above the sound of their own jet engines.”

Since quiet operation is essential to public acceptance of drones, it will be interesting to see if CR Flight can overcome this problem, especially at their mounts become larger, heavier, and load the propellers more.

CR Flight’s Technology

CR Flight’s web site includes a white paper on their technology.  The firm credits major differences between a conventional motor and their dual-spinning design.  “In a standard motor, the stator is stationary and propellers are
attached to the rotor. Power is transferred through electrical leads to the stator which in turn causes the rotor to spin. A single set of propellers spin to provide lift.”

Driving two propellers in opposite directions from the same motor is a neat design trick

The CR Flight system is a bit counter-intuitive, as well as contra-rotating.  “In the CR Motor, the armature and rotor are free to move independently. Power is delivered through the Rotary Transformer™ to the armature.
The armature sits on a set of bearings, the same as the rotor, allowing both to rotate in opposite directions. When power is transferred to the armature, it applies a force which drives the while the second propeller attached to the
armature is driven in the opposite direction. Both the rotor and armature are anchored to a single shaft, which is fixed to the drone.”

CR Flight claims this approach allows the motors to run much cooler, produce more thrust than conventional motors and last longer.  Their “Made in the USA” status will give them standing in what may become a more patriotic nation, and their apparent quality and time between overhauls will make them favorites with fleet operators.  We will be checking in with them.


MAHEPA and HY4 Go High

MAHEPA (Modular Aproach to Hybrid-Electric Propulsion Architecture) is a European Union project to build emission-free aircraft.  A public flight of Pipistrel’s HY4 hydrogen-powered, four-seat aircraft was the latest demonstration of the group’s progress.

Challenging Objectives

Overall, MAHEPA hopes to accomplish five objectives:

  1. Advancing the fuel-driven serial hybrid-electric Powertrain which uses a lightweight internal combustion engine (ICE), capable of running multiple fuels as the power generation module.
  2. Advancing the reliability of zero-emission serial hybrid-electric powertrain which uses a Proton Exchange Membrane (PEM) Hydrogen Fuel Cell (FC) as the power generation module.
  3. Advancing new airborne qualified, lightweight, high-power density components such as a 200 kW+ electric motor, a 100 kW+ generator and improved power electronics using Silicon Carbide (SiC) technology to increase efficiency of power transmission due to decreased switching losses.
  4. Developing “common building blocks” solutions also for different aircraft configurations, enabling the proliferation of powertrain modules between various aircraft.
  5. Gathering, analyzing and comparing in-flight performance and emission data in order to quantify the advantages and limitations of the hydro-carbon fuel-driven and zero-emission power generation modules.

Horizon magazine reiterates the case for and the issues confronting development of such new vehicles.

An H2 Hackathon

A surfeit of talent is ready to tackle those issues, and the variety of approaches is heartening.  For HY4 as it flies currently,  The MAHEPA consortium includes Pipistrel Vertical Solutions, Compact Dynamics, DLR, H2Fly, Politecnico di Milano, TU Delft, University of Maribor and University of Ulm.

The Big Reveal

Those lucky enough to see the airplane after its Slovenian shakedown flight went to the Stuttgart Airport at the behest of this invitation.  It has, after all, a European-wide permit to fly and we be at the Stuttgart airport until May 2021.

“Dear Sir or Madam, On Friday, December 11th, 2020, the developers and sponsors of the world’s first four-seat hydrogen fuel cell aircraft Hy4 will present the sixth and latest generation of emission-free drive technology to the public at Stuttgart State Airport. The further developed Hy4 recently received a flight permit from the licensing authorities to carry out test flights. In the next ten years, the technology should mature to the point where it can be transferred to 40-seat regional aircraft. Flughafen Stuttgart GmbH, together with Ulm University, H2FLY GmbH and NOW GmbH, cordially invite you to the official presentation of the Hy4. On the occasion of the milestone reached for climate-friendly passenger flights, the Federal Transport Minister Andreas Scheuer (via video message) and the Baden-Württemberg State Transport Minister Winfried Hermann speak. The event will be broadcast live on the h2fly.de website. We look forward to your participation.”

The Long Dance Version

For Those of us unable to make it to Germany for the event, the project personnel thoughtfully made a video for us, a longer visual reprise of the first short video on this blog entry, which at about 1:17:35 dissolves to the current day – evidenced by the face masks worn by all present.  With somewhat extreme social distancing for the camera crews, speakers start Deutsche sprechen at the 1:24:10 mark.  At about 1:53:15, the press conference ends and we get yet another iteration of the HY 4 flying in sunny skies.

MAHEPA’s announcement expanded on the technology and its future possibilities.  “With the renovated and optimized fuel cell system technology developed in MAHEPA and in strong cooperation with multiple national projects, the Hy4 became the most powerful hydrogen fuel cell driven aircraft ever made, directly flying into the next era of air transport. First qualification tests and data dissemination show that the full redundant Hy4 powertrain architecture allows an upscaling of the modular technology.

“MAHEPA consortium of Pipistrel Vertical Solutions, Compact Dynamics, DLR, H2Fly, Politecnico di Milano, TU Delft, University of Maribor and University of Ulm is again demonstrating a pioneering direction towards cleaner air transport in Europe, which will be supported by novel technologies developed in the project.”

In GreenCarCongress’s article, perspicacious reader “SD” comments, “Appears to be 2 Pipistel Taurus self-launching sailplanes put together with a new center wing section with the propulsion system. A somewhat strange and not a very practical aircraft but it was probably a low cost way to get something that would fly. Note that Pipistel builds the Taurus in a battery electric self-launching version with a retracting motor and propeller. They also offer battery electric training and light sport aircraft.”

Questions of practicality aside, designer Tine Tomazic used existing Pipistrel Taurus G2 glider parts to make a four-seat entrant for 2011’s NASA Green Flight Challenge.  Originally powered by batteries and powered by a 200-horsepower motor, the G4 achieved 403.5 passenger miles per gallon equivalent (compared to a conventional fossil fuel load).  His thinking was a bit audacious but clever, NASA’s rules gauging the winner by Passenger Miles per Gallon.

Because of its demonstrated aerodynamic cleanness, it was well suited for adaptation of hydrogen power, and thus began a second career.

Plentiful Resources

The MAHEPA Project provides a bounty of material on H2 aviation.  Their web site includes a 64-page overview, Towards Climate-Neutral Aviation from the European Commission.  Downloads and Results show even more educational material.

MAHEPA seems to be, in an archaic phrase, going full steam ahead.  We look forward to their further successes.


Airbus Goes Modular with Hydrogen Pods

Airbus announced its Zero E program in late September, showing three possible candidates for hybrid hydrogen power.  Zero E, for zero emissions, is a tall order even for one of the world’s two largest aircraft companies.  Now, the company makes yet another announcement – for a novel modular “pod” configuration – “a stand-alone propeller propulsion system powered by hydrogen fuel cells. It consists of the following elements:”

  • A propeller
  • Electric motors
  • Fuel cells
  • Power electronics
  • LH2 tank
  • A cooling system
  • A set of auxiliary equipment

Instead of housing the hydrogen fuel in the fuselage, Airbus creates a more spacious cabin by moving fuel storage to each pod.  Each pod would be identical and modular.  Components could be removed and replaced quickly, and if necessary, the entire pod could be removed for maintenance.  One startling possibility, that of dropping a pod if it caught on fire, would probably not be well received in areas of dry forests or brushland.

Liquid hydrogen and atmospheric oxygen combine in the fuel cells to generate electric current and run the motors.  Eight-bladed composite propellers shaped to “provide added thrust during the takeoff and climb-out phases of flight” would mean high performance and lower “fuel” usage.

Glenn Llewellyn, VP of Zero-Emission Aircraft, explains, “This is one option, but many more will be conceptualized before we make a final selection, a decision that is expected by 2025.”

Addison Schonland’s interview with Airbus Chief Technology Officer Grazia Vittadini sheds light on what the aviation giant hopes to accomplish with H2.  They discuss operating costs, environmental concerns, and other aspects of hydrogen use.  They mention Elring Klinger fuel cell stacks at one point, a possible indication of future suppliers.

Don’t look for this on flight lines any time soon.  Glenn Llewellyn points out, “This is one option, but many more will be conceptualized before we make a final selection, a decision that is expected by 2025.”  This is an idea pursued since at least 2018, when a recently published patent on the technology had its first application.

A Year-end Projection: Where Hydrogen May Go Next

GreenTech Media.com shows us major advances in hydrogen production and applications, something we might not have seen coming a few years ago.  It’s a year-end reminder that the future might really get better – at least in the energy field.


Something to Lighten the Post-Holiday Letdown

Even following Boxing Day, we have a few items to re-gift to our faithful readers, and close out the season with four very light examples of electric aviation.


Felix Ruhle has been improving and refining a basic wing design for over a decade, growing a line of aircraft that range from simple hang-gliders to fairly sleek, self-launching, electrically-powered ultralight sailplanes.  The A-I-R factory/showroom in Halblech, Germany, one of 18 dealerships around the world, fronts a lush green meadow and houses a plethora of ATOS wings.

The ATOS wing, coming in a range of sizes, can be attached to seemingly anything from a simple jump-off-the-nearest cliff hang-gliding rig to refined, electrically-powered ultralight sailplanes.

Under development for the last few years, the ultralight sailplane merits even A-I-R’s enthusiastic approval.  “The newest development of A.I.R. is revolutionary! The foldable electric powered. nearly noiseless ultralight-aircraft is based on the proven Atos hang-gliding wings! With 3-axes-steering, real elevator, retractable landing gear and propeller, as well as a sleek closed cockpit you will enjoy to expand your cross country flights. It can be easily transported on car or in a trailer and built up by one man in approximately 15 minutes like a hang-glider.”

Falling in the 120 kilogram (264.6 pounds) empty weight that allows unregulated flight, the wing is derived from the rigid wing hang glider Atos, and has flaps, spoilers and airbrakes.  Its 14.5-meter (47.6-feet) wing gives a best glide ratio of 1:28 at 75 kilometers per hour (46.6 mph), very close to what older standard-class sailplanes could manage.  A sink rate of only 0.65 meters per second (128 feet per minute) means it can float on the lightest thermal.  It can carry up to a 110 kilogram (242.5 pound) pilot, a good load-bearing ability.

With the advantage of self-launching because of its 16-kilowatt (21.5 hp) Eck/Geiger electric motor, it can take off in only 40 meters (131 feet) and climb at 3.5 meters per second (689 feet per minute), according the A-I-R.

A-I-R recommends the craft for, “Experienced hang-gliding XC-pilots who want to make longer tracks with thermal[s] and the warranty to come back home!”   With an endurance of up to four hours and a range of 320 to 480 kilometers (200 to 300 miles), pilots can wander a long way from home.  The firm adds the plane is right for, “Glider pilots who prefer independence combined with the safety of a self launching glider and a favorable price!”

The ATOS looks to be an ideal craft for those seeking adventures without the need to drag all of ones friends and relatives along for the ride.

Two Electric Quickies

The 2011 NASA Green Flight Challenge had a promised field of a baker’s dozen entrants, although only four made the starting line.  It was a challenge, after all.  One that almost showed was the eQuickie, an electric variant of Burt Rutan’s little speedster.  An unfortunate hard landing damaged the canard’s landing gear and kept the little gem from competing.

One in Ukraine

And now, almost 10 years later, two rebirths of the idea come to light – one, from Ukraine and chief designer Yuri Yakovlev.

Aeroprakt, a successful light sport aircraft maker with over 900 examples of its high-visibility Vixens and Foxbats flying, was started by a young Yuri, who crafted a Rutan Quickie look-alike powered by an inverted two-stroke, two-cylinder engine.  After a 29 year hiatus, Yuri brought the plane back to life with an electric power plant and a six-blade propeller.  Interestingly, the blades are arrayed in two rows of three each.  A video that includes other electric aircraft switches to coverage of the electric Quickie at 1:46.  It provides interesting close-ups of batteries, propeller and motor.  YouTube has yet to provide translations, but the pictures are universally understandable.

Another video gives a glimpse of ground testing.

And another lets us follow the first takeoff and hurried landing.

To see more, check out this Facebook page, but remember to click the “translate” prompt unless you read Ukranian.

Henry Hallam’s Reverse Thrust QuickLi

Equally surprising, your editor discovered that Henry Hallam, part of Joby Aviation’s motor development team, had resurrected a Quickie, installed an Emrax motor, his own silicon carbide (SiC) controller, and as an apparent part of that controller, a propeller that can be literally reversed.

He shows a holiday-festive set of battery packs here.  “First three packs complete(ish). Each is 12s4p Sanyo NCR18650GA, monitored/balanced by an LTC6804-1. N22QE will have 27 packs total for 15.2 kWh @ 235 Wh/kg. This will give about 75 mins flight time.”  His honest energy per kilogram at the pack level is greatly appreciated.

His terse note here explains the noisy sound track: “Constant torque ramp to 5000 rpm (takeoff speed) then idle.”

Accompanying this video, his notes help make sense of the sights and sounds.  “The QuickLi (or Quick-E) is a single-seat electric self-launching motorglider. Based on the Rutan Quickie (Q1) airframe with an Emrax 208 motor (~40 kW takeoff, ~12 kW cruise) and a Catto fixed-pitch composite propeller. The motor is driven by a DIY inverter design using silicon carbide MOSFETs at 99.6% efficiency. Battery packs based on NCR18650GA cells store a total of 15 kWh at a packaged energy density of 233 Wh/kg. The electrical powertrain is designed with a semi-redundant fail-safe architecture that allows safe flight to be completed after failure of any component including battery or inverter, yet all components are used during normal operation to maximize efficiency (no hot spares).”

And Something (Almost) Lighter than Air

French company Voliris set out to win a Guinness award as the world’s smallest airship, and proudly displays the evidence of their success at the end.

Finally, something meditative and serene.  Aerosculpture blends art and technology into items of great beauty.   The firm, based in Montebourg, France, almost due south across the English Channel from Portsmouth, England, hopes to reinvigorate balloon flight in a center once part of that history.

We hope they can succeed, and bring a quiet joy to the skies over France.


Sunseeker Duo Plays Among the Alps

Eric and Irena Raymond took a lovely Sunseeker Duo flight over the Italian alps near their home in Voghera and edited it all into a video.  They designed and built their own solar-powered airplane – Eric’s third.  He flew Sunseeker 1 across the US in 1990 in 21 hops.  A big press conference scheduled for his last landing at Kitty Hawk, NC was a big disappointment since the US invaded Kuwait that day.

Six Minutes of Great Beauty

Their airplane has solar cells arrayed across the wing and horizontal tail, a small battery pack that gets recharged while flying in the sun, and a 22 kilowatt (30 hp) motor on the tail.  Turning off the motor they can soar on winds wafting up the sides of the mountains.  Beeping and electronic noises come from an audio variometer, a sensitive indicator of whether the airplane is climbing or descending.  All the sounds are ambient.  Note how quiet the airplane is, even under power.

They use GoPro cameras on long selfie sticks mounted on the right wing and nose.  Special software allows Eric to edit out the stick itself, but not its shadow.  Eric and Irena are both professional photographers, BTW.  Their work is featured in GoPro TV commercials.

An Inside Look

 In a video made earlier this year, Eric shares background on the design of the aircraft, and gives a tour of the cockpit and the many innovations therein.

A Grand Finale

Eric’s comments for this final YouTube video might help orient the viewer  It might be a real treat on virtual reality (VR) goggles.  “After soaring over the Alps for 2.5 hours, this is a final pass over the ridge before heading home to get warmed up.  Filmed on December 13, 2020, north of Udine, Italy in the Julian pre-Alps. Best viewed on a tablet or mobile phone that can be moved around to see the views.”  This works beautifully even on a conventional computer monitor.

Just like your rear-view mirror, objects may be closer than they appear.  Pivot the view around to a rearward perspective to see how closely the Duo shadows the ridge as it descends.


ZeroAvia Gains Backing at High Levels

“Cannot be more proud and humbled to be a part of this stellar team!”  That’s power train developer Gabriel DeVault’s response to ZeroAvia’s Chief Financial Officer Katya Akulinicheva’s enthusiastic endorsement of Bloomberg LP’s news.  She listed the investors taking an active interest in ZeroAvia, including Ecosystem Integrity Fund, Breakthrough Energy Ventures, the Amazon Climate Pledge Fund, Horizons Ventures, Shell Ventures and Summa Equity.

Already benefiting from a $16.3 million grant from Innovate UK, Aerospace Technology Institute and Department for Business, Energy and Industrial Strategy (BEIS), ZeroAvia will be able to push forward on plans to create a 19-seat hydrogen-powered commuter liner.

According to Bloomberg, “ZeroAvia aims to demonstrate that it can fly a plane 500 miles (804 kilometers) with as many as 20 seats by 2023. It wants to scale up to 1,000 miles with over 100 seats by 2030.”

With individuals such as Bill Gates and Jeff Bezos taking an interest, an aviation blog now feels a little like a financial report.  The $38 million raised from the UK government and private investors will enable ZeroAvia to replace fossil fuel burners with a hydrogen fuel-cell system.

A Full Dance Card

Val Miftakhov, ZeroAvia’s Chief Executive Officer announced that 10 airlines are ready to buy his company’s 20-seat offering when the craft is available by 2023.  That’s an ambitious schedule, and plans to work with British Airways will help push things forward.  Throughout Europe, efforts are underway to decarbonizes domestic flights, so ZeroAvia’s initial small commuter liner will fit that mission profile nicely.

Bloomberg Green reports, “ZeroAvia aims to demonstrate that it can fly a plane 500 miles (804 kilometers) with as many as 20 seats by 2023. It wants to scale up to 1,000 miles with over 100 seats by 2030.”

Greentech Media reports Val Miftakhov explaining that ZeroAvia’s first Powertrain for 20-seater planes fits a neat market niche.  “About 10,000 such planes are operating in the market today, commonly used in hub-and-spoke operations such as air freight, where the planes are returning to a central depot on fairly predictable schedules, he said. Amazon Air, the retail giant’s freight fleet, has around 70 aircraft in operation.”

To power larger craft, ZeroAvia will need higher power density fuel cells.  “The power density is around 3 kW per kilogram for a small [rotor] turbine. For a Boeing 777, that figure needs to be around 10 kW per kg. In the automotive sector today the density is 0.7 kW per kg. As we work on that, increasing it further and further, we get more segments unlocked,” [Miftakhov] said.

“We’re already flying our prototypes. We have the world’s largest hydrogen-electric aircraft in the air,” he said. “So we’re not just making projections or running around with PowerPoints; we’re actually doing it. And we have a pretty good idea how to achieve a big competitive position in three years with an actual commercial product.”

Keeping it Local

Hydrogen is a great fuel except for the lack of local filling stations that can supply it.  California, for instance, has the greatest number of H2 stations, 42.  With 8,980 fuel cell cars owned or leased in all of America, the chance of finding a station is great – if you drive in the Los Angeles, San Francisco bay area, or are on the road to Reno.  Only two other H2 stations exist in the U. S., and they probably don’t have Quickie Marts attached.  There are doubtless even fewer such stations on airports anywhere.

ZeroAvia seeks to overcome that shortage by partnering with EMEC, the European Marine Energy Center Ltd., Enapter, and Aeristech.  At a macro level, EMEC uses wave and tidal action to produce electricity and hydrogen from excess generation on Orkney Island.  The site also hosts small companies that have various systems and devices to produce H2.   Neil Kermode, Managing Director at EMEC, sees great promise in the alliance.  “As well as providing green hydrogen to demonstrate zero carbon aviation, EMEC will develop a hydrogen refueling solution capable of dispensing volumes approaching the speed of commercial aviation. This will be a major step forward for the sector.”

Possibly part of the refueling solution, Enapter is maker of a patented anion exchange membrane (AEM) electrolyzer for hydrogen production from water and electrical energy.  They have reduced the “water splitting” system to a size transportable in a van.  Their modular AEM system can be “ganged” for different sized operations.  All such production will take place on the airport where hydrogen-powered craft will be deployed, obviating the need for transport from distant sources.

Squeezing More Power from H2

ZeroAvia is also partnering with Aeristech, which makes electric superchargers.  Since the motor driving the supercharger is small, light and not directly coupled to the engine, throttle response can be quick, since the 2.5 kilowatt compressor motor can spool up from 0 to 80,000 rpm in 0.3 seconds.  Pushing additional air through a fuel cell will evidently add to the output, like raising the voltage in batteries.  The company, expanding into aerospace, will move into “an advanced facility” in the West Midlands and add “up to 60 new roles, in highly skilled areas such as power electronics and motor drive engineering.”

Aeristech’s advanced motors and controllers may point the way in new power sources while backing the hydrogen project with ZeroAvia.  All players in the enterprise seem to be creative and ambitious.  So many brilliant minds working on a common solution should lead to clean skies and pollution-free transport.