The Great Human Powered Aircraft Race -2022

A New Crew of Magnificent Men in Their Flying Machines

Fred To, former head of the British Human Powered Flying Club, has shared a major announcement.

“The Great Human Powered Aircraft Race will take place in June 2022 and is now open for entries. Teams will attempt to cross the Channel from England to France in an aircraft powered solely by the pilot’s pedaling. They will compete for a £50,000 ($68,785) prize awarded to the team that crosses the Channel fastest, with £10,000 ($13,757) for the second fastest team and £5,000 ($6.878) for the fastest female pilot.

“The first and only crossing of the Channel in a human powered aircraft (HPA) was 42 years ago by Bryan Allen in the aircraft Gossamer Albatross designed by Paul MacCready; no successful attempts have been made since.
Human-powered flying remains one of the world’s most exclusive sports, with more people having flown into space than have flown a human powered aircraft. This is largely due to the sheer difficulty flying for any length of time in a HPA. The race will combine extreme engineering with extreme athletic ability.

“The race will mark the 60th anniversary of the first flight of human-powered aircraft by Derek Piggott in the Southampton University student’s aircraft SUMPAC, it will also celebrate the original Channel crossing in 1979 by pilot Bryan Allen. It is kindly supported by Anne Williams, one of the creators of SUMPAC. The race is also endorsed by Marshall MacCready, son of Paul MacCready who designed Gossamer Albatross, the first and only HPA to cross the channel.

“‘Crossing the English Channel in a human powered aircraft — it has been done, once before. Barely. It was one of the most amazing athletic achievements of our time. To think that several international teams are going to attempt the same feat, on the same day, in a race to see who is the fastest, seems almost a bit bonkers. It will be a huge technical and logistical challenge, but most of all a supreme test of athletic and piloting skill. It is going to be fascinating to watch, and thrilling to participate in.’

Alec Proudfoot- HPA Designer.

‘One of the aims of the competition is to use the race to inspire the next generation of engineers and scientists.’

Fred To- Race organizer

“Entrants will have to fly 35 kilometers (21.7 miles) from Folkestone across the Channel to France. All aircraft will take off on the same day to ensure no team has an unfair advantage due to weather though take offs will be staggered to ensure there are no mid air collisions. It is the first human powered aircraft time trial in history with multiple teams in the air simultaneously which will prove incredibly exciting. Prize money will be awarded based on the quickest crossing. Teams will be followed by speed boats with rescue divers standing by in case an aircraft ditches.

“Prospective teams should contact the organizers if they are interested in competing in the world’s first and only time trial HPA race across the Channel. On account of the risk and difficulty teams will have to demonstrate past experience in HPA building to qualify. Teams from all countries are invited to apply.

“‘Flying a human powered aircraft is the most amazing experience: a bit of appropriate nervousness before take off, followed by swift pedaling and the noise of the wheels on the tarmac, and then suddenly it becomes quiet and you are floating, like a magic carpet ride. It’s virtually silent except for your own labored breathing, and the receding excited shouts of your teammates. Magical.’   (Above, we see Alec’s Dash HPA in flight at Moffett Field in 2016, piloted by Craig Robinson.)

Alec Proudfoot- HPA Designer

“The race will mark the 60th anniversary of the first flight of human powered aircraft by Derek Piggott as well as celebrating the original Channel crossing in 1979. It is kindly supported by Ann Williams (one of the creators of SUMPAC, the world’s first human powered aircraft) and Marshall MacCready (son of Paul MacCready, designer of the Gossamer Albatross, first and only HPA to cross the channel).”

“As aircraft are powered entirely by pedaling, HPA racing is one of the world’s most sustainable airsports with each HPA being a miracle of efficient engineering. As humans have a much lower power to weight ratio than conventional engines the aircraft will have to be incredibly light. It is common for a HPA with a 30 meter wingspan to only weigh 40 kilograms (88.2 pounds), less than the pilot. Every gram saved reduces the amount of cycling power that the pilot needs to produce and will be vital to determining whether the aircraft will make it across the Channel.

“It is the largest prize announced for human powered airplanes since the Kremer Prizes were created in 1959 and organizers are hopeful that the race will inspire the next generation of HPA pilots and engineers along with increasing STEM engagement among students.”

Those excited by this announcement have over a year to prepare themselves and their machines for a great challenge and a festive occasion.  Peleton® should add a new category to their trainers.

Since we have compared the Great Human Powered Aircraft Race to Magnificent Men in their Flying Machines, here is a review of that 1965 film, an expensive production with Derek Piggott as the flight chief and more than occasional pilot for all the craft.  Shot in high-grade 70-millimeter with excellent production values, the film, despite its age, holds up well, and the flying is… magnificent.

To contact the organizers and perhaps attain your own glory, here is the contest’s address:

Thanks to Bryan Allen himself for alerting your editor.

Added April 12

Fred To sent along this further recognition from the British newspaper, The Daily Telegraph.  As Fred points out, “Now comes the really hard work.”

Mike Truelove with his human-powered airplane, presumably “Aerocycle 3.”

In the video, Mike Truelove pedals his Aerocycle from the grass, requiring extra effort to overcome drag from the irregular surface.  Imagine gaining altitude and pedaling for 22 miles.


Electrifly-in: Grenchen 2021

Electrifly-in, formerly the Smartflyer Challenge, is on for September 11 and 12, 2021, in Grenchen, Switzerland.  The event, even held in 2020 despite the pandemic, is a compact showing of the latest in electrical aircraft and technology.  Watch as this 2019 video as a Φnix (the Greek letter phi + nix –a clever bilingual pun) takes off, circuits the area and makes a landing – all the time flying with other electric aircraft.

In this flight, you can see the compact airport (including a grass landing strip) and a lovely setting for a great event.  Started as the Smartflyer Challenge* in 2016, the gathering has changed its name to be more inclusive.

Last year, even with travel limitations imposed worldwide, saw a healthy turnout of all-electric flyers, ranging from ultralight electric “trikes” to cross-country tourers.

From 12 to 50 Kilowatts and Beyond

Powering a large number of machines on last year’s flight line, Eck-Geiger Engineering makes a range of motors from 12 to 50 kilowatts in power.  On their web site, the firm lists over 30 different types of small aircraft powered by their motor/controller/battery packages.  These range from the ultralight, hydrogen-fueled La Mouette wing that Gerard Thevenot flew across the English Channel in 2009 to powered balloons and hybrid ultralight aircraft.  Many of these machines have made appearances at previous years’ events, and more are sure to be on hand this year.  Here we see a hang-glider “trike” powered by a 20 kilowatt unit.

And in another example, the Birdy motorglider flown by Toni Roth at last year’s event, the self-launcher flies on a mere 16 kW (21.6 horsepower).  All these and more could attend this year’s Electrifly-in.

Other manufacturers, including Pipistrel with their proprietary line of power systems, YASA, R0lls-Royce, MGM-Compro and others may provide insights into the future of battery and possibly hydrogen aviation power.

Pioneering Pilots and Speakers

Last year, Eric and Irena Raymond showed up in their Sunseeker Duo, Klaus Ohlmann flew a Lange 20e self-launching sailplane, and Bertrand Piccard, co-pilot of Solar Impulse flew an ultralight and discussed   Ten years ago, Eric and Klaus flew the second-place winning e-Genius in the NASA Green Flight Challenge sponsored by Google.  They flew a 200-mile course around northern California and averaged 375.8 passenger miles per gallon, using the energy equivalent of a little more than a gallon of gasoline for the flight.  This kind of energy efficiency and economy will continue to draw attention to the new technology, now becoming entrenched.

Members of the record-breaking Pipistrel Electro Velis team were there for a discussion on electric aviation, just part of a larger symposium that provided a socially-distanced learning experience for all.  Speakers from government, industry and academia filled out the program.  Hangars full of displays and aircraft on the flight line helped make the two-day event a full one.  Your editor wishes he could be there this year, and it’s not too early to start making travel plans.

*The Original Namesake

The people behind the Smartflyer hybrid touring airplane have kept the appellation for the craft, featured at past events on the Grenchen field.  This airplane should be on display at this year’s fly-in, and may have started flight testing by September.

Specifications (from their web site)

  • Cruise Speed 120 knots (138 mph) / 222 km/h
  • Take off Power 160 kilowatts
  • Max Cont. Power 120 kW (161 hp)
  • Seats 4
  • Range 400 NM (460 statute miles) / 750 km
  • Endurance 4 h
  • Empty Mass 1000 kg (2,200 pounds)
  • Take off Mass 1400 kg (3,086 pounds)
  • Battery Mass 160 kg (353 pounds)
  • Range Extender Rotax 914 with YASA (Yokeless and Segmented Armature) Generator

The specifications may change during the construction process.

This year’s Electrifly-in should be even bigger once travel restrictions are lifted.  Again, it seems like two days filled with a glimpse of future, green flight.


Massless Batteries for Aircraft?

What if the weight of the batteries in an electric airplane could virtually disappear?  Researchers at Chalmers University of Technology in Gothenburg, Sweden have come up with an improved structural battery that exceeds the results of earlier research.  So-called “massless batteries,” although not as energy dense as cylindrical or pouch lithium-ion batteries, could be worthy substitutes.

The idea of making airplanes from materials that would provide energy from their inherent properties has been of interest for years.  Your editor wrote an article on “The Grand Unified Airplane” for Kitplanes magazine in 2013 based on the idea of combining solar power, piezoelectric flexing of wings, and structural batteries.  The ultimate goal was to create a machine that would move through the air on the energy of flight itself.  This might seem an unreachable fantasy, but material scientists are bringing us closer to the dream.

Chalmers University points out, “Structural battery composites cannot store as much energy as lithium-ion batteries, but have several characteristics that make them highly attractive for use in vehicles and other applications. When the battery becomes part of the load bearing structure, the mass of the battery essentially ‘disappears’”.  Illustration: Yen Strandqvist

Headlining their report with a rather non-academic boast, Chalmers University promotes its, “Big breakthrough for ’massless’ energy storage.  ”They follow with an intriguing first paragraph.  “Researchers from Chalmers University of Technology have produced a structural battery that performs ten times better than all previous versions. It contains carbon fiber that serves simultaneously as an electrode, conductor, and load-bearing material. Their latest research breakthrough paves the way for essentially ’massless’ energy storage in vehicles and other technology.”

Before getting too excited about that “10 times” claim, recognize that previous structural batteries did not display high energy densities, the property that keeps the Energizer Bunny hopping.  Chalmers notes the new battery has an energy density of 24 Watt-hours per kilogram, only about 20 percent that of comparable lithium-ion batteries.  It’s slightly less than one-tenth that of the best battery packs used in state-of-the-art aerial vehicle.

Chalmers structural battery shows considerably higher strength, energy density than those of previous researchers

Chalmers explains why this is not a total loss.  “But since the weight of the vehicles can be greatly reduced, less energy will be required to drive an electric car, for example, and lower energy density also results in increased safety. And with a stiffness of 25 GPa (GigaPascals equaling 3,625,943 pounds per square inch), the structural battery can really compete with many other commonly used construction materials.”  Depending on the weight of composite materials used, the structure might be no weightier than a more conventional equivalent.

Consider, though, a possible application of such energy-storing materials.  Let’s use the 24 kW/hr materials applied to Calin Gologan’s Solar Elektra One, introduced in 2012.  The plane was a 3/3 machine, 1/3 structure, 1/3 batteries, and 1/3 payload including pilot.  Each third was 100 kilograms (220 pounds).  Imagine being able to replace half the structure with Chalmers’ structural battery material.  50 kilograms (110 pounds of the airframe would be capable of storing 1,200 Watt-hours per kilogram, shaving 4.6 kilograms (10.1 pounds) from the battery weight.  Not a big number, but still 1.5 percent of the total aircraft weight.  Chalmers researchers predict up to three times the energy density for future products, so that would equal a 4.5 percent reduction.  As on the Grand Unified Airplane concept, if those structural panels were also solar collectors, even more benefit could accrue in terms of extended range.

Calin Gologan’s PC Aero One, a 2012 design, light as it is, would benefit from structural batteries.  Greater strength and energy density are coming, according to researchers


Chalmers’ research is linked to earlier efforts by Emile Greenhalgh at Imperial College in London, who was affiliated with work at Volvo to develop structural body panels that would store energy.  Ongoing research was named by Physics World as one of 2018’s ten biggest scientific breakthroughs.

Leif Asp, Professor at Chalmers and leader of the project explains, “Previous attempts to make structural batteries have resulted in cells with either good mechanical properties, or good electrical properties. But here, using carbon fibre, we have succeeded in designing a structural battery with both competitive energy storage capacity and rigidity.”

Doctor Johanna Xu with a newly manufactured structural battery cell in Chalmers’ composite lab, which she shows to Leif Asp. The cell consists of a carbon fiber electrode and a lithium iron phosphate electrode separated by a fiberglass fabric, all impregnated with a structural battery electrolyte for combined mechanical and electrical function. Image: Marcus Folino

The new battery has a negative electrode made of carbon fiber, a positive electrode made of a lithium iron phosphate-coated aluminum foil, separated by a fiberglass fabric, in an electrolyte matrix.  Researchers “did not choose the materials to try and break records – rather, they wanted to investigate and understand the effects of material architecture and separator thickness.”

The samples of Chalmers structural batteries shows different materials used

Further research financed by the Swedish National Space Agency will attempt to enhance the performance of the structural battery.  “The aluminum foil will be replaced with carbon fiber as a load-bearing material in the positive electrode, providing both increased stiffness and energy density. The fiberglass separator will be replaced with an ultra-thin variant, which will give a much greater effect – as well as faster charging cycles. The new project is expected to be completed within two years.”

Leif Asp, leading this project too, estimates that such a battery could reach an energy density of 75 Wh/kg and a stiffness of 75 GPa (10877830 psi) – about as strong as aluminum, but at a much lower weight.  He takes an optimistic view.  “The next generation structural battery has fantastic potential. If you look at consumer technology, it could be quite possible within a few years to manufacture smartphones, laptops or electric bicycles that weigh half as much as today and are much more compact.”

And in the longer term, it is absolutely conceivable that electric cars, electric planes and satellites will be designed with and powered by structural batteries.

Lief Asp concludes, “We are really only limited by our imaginations here. We have received a lot of attention from many different types of companies in connection with the publication of our scientific articles in the field. There is understandably a great amount of interest in these lightweight, multifunctional materials.”

The research team’s paper, “A Structural Battery and its Multifunctional Performance,” can be found in the journal Advanced Energy Sustainability.  Authors include Leif E. Asp, Karl Bouton, David Carlstedt, Shanghong Duan, Ross Harnden, Wilhelm Johannisson, Marcus Johansen, Mats K. G. Johansson, Göran Lindbergh, Fang Liu, Kevin Peuvot, Lynn M. Schneider, Johanna Xu, and Dan Zenkert

Making the Chalmers structural battery at the laboratory level. The processes should be able to be scaled to industrial levels

The structural battery uses carbon fiber as a negative electrode, and a lithium iron phosphate-coated aluminum foil as the positive electrode. The carbon fiber acts as a host for the lithium and thus stores the energy. Since the carbon fiber also conducts electrons, the need for copper and silver conductors is also avoided – reducing the weight even further. Both the carbon fiber and the aluminum foil contribute to the mechanical properties of the structural battery. The two electrode materials are kept separated by a fiberglass fabric in a structural electrolyte matrix. The task of the electrolyte is to transport the lithium ions between the two electrodes of the battery, but also to transfer mechanical loads between carbon fibers and other parts.

The project is run is a collaboration between Chalmers University of Technology and KTH Royal Institute of Technology, Sweden’s two largest technical universities. The battery electrolyte has been developed at KTH.  The project involves researchers from five different disciplines: material mechanics, materials engineering, lightweight structures, applied electrochemistry and fiber and polymer technology.

Funding has come from the European Commission’s research program Clean Sky II, and interestingly, from the U. S. Air Force.


Landing in the Baobab Trees with eHang

eHang, expanding its horizons with its two-passenger EH216 autonomous aerial vehicles (AAVs), has announced a partnership with Italian architecture firm Giancarlo Zema Design Group (GZDG).  GZDG’s eco-sustainable, Baobab tree-mimicking vertiport will act as a landing zone for eHang’s electric Vertical Take Off and Landing (eVTOL) craft.

eHang 216 approaching Baobab-inspired landing site

Basing its design on the Baobab tree, native to Madagascar, Africa, and Australia, GZDG’s structure will fit into urban and rural environments equally well.  The 30-meter (98.4-feet) tower, built of laminated wood and steel emulating the shape of the “Tree of Life,” the vertiport will be topped with a multi-purpose landing deck.  The structure will incorporate a waiting room, café, a 200-square-meter (2,153-square-foot) panoramic restaurant and connecting lift.  Non-slip photovoltaic panels will generate over 300 kilowatts of electric power per day.

Avenue of the Baobabs (UNESCO World Heritage site), Madagascar. Trees are also found in Africa and Australia

GZDG’s vertiport is a green design made of sustainable construction materials, “and can generate energy to recharge the EH216 passenger-grade AAVs.” According to the partner’s joint press release, “Vertiports will play a significant role in the Urban Air Mobility (UAM) market and the new era of flight. When integrated into the existing transportation infrastructure, vertiports can serve as aerial hubs for tourists.”

Plan view for eHang’s Baobab landing zone shows charging modules, central lift

With the first Baobab vertiport being built in Italy, EHang and GZDG aim to enter the emerging global eco-tourism sector, with multiple projects being planned in Europe and Southeast Asia.

eHang is already exploring those projects with a strategic partner based in Hong Kong.

Real-estate company Greenland Hong Kong Holding Limited operates a tourism site called Forest Lake (translated as Yuehu Town) located in Zhaoqing, a popular tour destination city in Guangdong, China.   eHang will provide aerial sightseeing and aerial media shows.  Beyond this site and the first Baobab vertiport in Italy, the partners hope to expand to other locations in Europe and Southeast Asia.

With green building practices and green aviation in partnership, tourism might flourish in a way that is actually helpful for the planet.


Two electric regional commuters are nearing reality.  A Scylax design from Calin Gologan reflects its “clean sheet” origins: the other, derived from an existing Tecnam design, honors its Italian craftsmanship heritage.

Calin Gologan, Rosario De Luca and the Scylax E Series

Calin, designing and building solar-powered aircraft since 2011 , and Rosario De Luca, Co Founder and CEO of EADCO GmbH and EADCO US LLC., and CEO of SCYLAX GmbH, have joined forces to create two small airliners, the Scylax E6 and E10, each enumerating its passenger capacity.  Joined by the airline FLN FRISIA-Luftverkehr GmbH Norddeich, they will begin flying their pure-electric craft soon with existing batteries enabling 300-kilometer (180-mile) trips.  Within the next decade, cell improvements will allow 600-kilometer with the same battery volume and weight.

The pair foresees a five-percent increase in battery capacity every year, making an easy case for ongoing improvements in energy storage, aircraft range, and greater power for safer takeoffs and climbs.

(Of interest in the video, Dr. Frank Anton, leader of Siemen’s electric aviation effort, supports the Scylax program, now allied with Rolls-Royce, which purchased the Siemens program.)

They see their aircraft as environmentally friendly, and with increasingly cleaner sources of renewable energy, yielding not only reduced or neglible emissions by the aircraft – but from the sources for electricity themselves.

The simplicity of electric motors will be a boon to operators, with only a pair of bearings requiring long-term replacement.  Scylax notes, “With no spark plugs, gears, belts, and other traditional mechanical parts that wear, SCYLAX’ electric propulsion systems are refreshingly free from the normal maintenance schedules that aircraft owners have become accustomed to.”

This level of reliability will be essential to safe flights on their Frisian airline’s routes.  These are mostly over water and at relatively low altitudes.  Some flights last mere minutes, but are the safest, quickest way to provide personal and cargo service to North Sea islands.

Frisian islands to be served by Scylax E6 and E10 aircraft

Looking beyond the immediate prospects for sales of Scylax aircraft, the partners project that, “The current market for single / twin engine aircraft is saturated with older legacy models and, due to the fuel savings associated with newer aircraft and models does not justify the cost of purchasing aircraft in the secondary market. The worldwide market volume was in 2018 ~1.740 units per year and USD 2.7 billion revenue. The all electric aircraft could build a real new market replacing the current old fleet with piston engines & turboprop propulsion.

“By leading the way to market and being a pioneer of electric aircraft, the E6 and E10 will be the natural replacement for companies looking to acquire or replace their existing aging small commuter fleet.”

Tecnam, Rolls-Royce and Norwegian Electricity

Building on their partnership in the H3PS Project, Italian aerospace company Tecnam is working with Rolls-Royce and Norwegian airline Wideroe to fly North Sea and West Coast routes.  The craft, based on the Tecnam P-Volt model, “Will be ideal” for those routes and the short take offs and landings necessary for the fields served.  The airplane should be ready for commercial service by 2026.

Wideroe’s route map shows numerous short routes and over-water hops

It’s of interest that similar aircraft will be flying similar missions in similar locations.  Stein Nilsen, Chief Executive for Widerøe highlights the similarities: Norway’s extensive network of short take-off and landing airports is ideal for zero emissions technologies. This aircraft shows how quickly new technology can and will be developed, and that we are on track with our ambition of flying with zero emissions around 2025.”

That timing would be on a fast track, considering that Rolls-Royce and Widerøe announced a joint research program in 2019, “to evaluate and develop electrical aircraft concepts that would fulfil the Norwegian ambition of having the first electrified aircraft in ordinary domestic scheduled flights by 2030 and 80 [percent] emission reduction in domestic flights by 2040.”

Developing clean electric aircraft may help Wideroe “build back better.”  They note that before the pandemic, the airline “offered around 400 flights per day using a network of 44 airports, where 74 [percent] of the flights have distances less than 275 [kilometers] (170 miles). The shortest flight durations are between seven and fifteen minutes.”  Again, the short flights are similar to those flown by FLN Frisia.

Based on the Tecnam P2012 Traveller aircraft, the electric P-Volt will be a short take off and landing (STOL) machine, able to land on grass strips.  Like northern Germany, many hops require takeoffs and landings on unimproved island airports and at least short hops over frigid waters.

Rob Watson, Director of Rolls-Royce Electrical, expands on the hopes for this partnership: “Electrification will help us deliver our ambition to enable the markets in which we operate achieve net zero carbon by 2050. This collaboration strengthens our existing relationships with Tecnam and Widerøe as we look to explore what is needed to deliver an all-electric passenger aircraft for the commuter market. It also demonstrates Rolls-Royce’s ambitions to be the leading supplier of all-electric and hybrid electric propulsion and power systems across multiple aviation markets.”

Fabio Russo, Chief Project R&D and Product Development, Tecnam, adds: “It is incredible to see the interest around the P-Volt, not only coming from regional airlines, but also from smart mobility-based companies. This last year has demonstrated the importance of promoting capillary connections between small communities, while reducing the congestion of the main hubs. The P-Volt, like the P2012 Traveller today, will perfectly fit the scope of this program. We are honored and pleased to see the level of enthusiasm Widerøe and our partner Rolls-Royce are dedicating to this project.”

Between the industrial giants partnering in Norway and the relatively small but no less inspired designers in Germany, electric aviation is finding an immediate need in less-served small airports.  The reliability and simplicity of electric aircraft will be a major factor in the future of air travel in such regions.


Hypoint’s Radical Radial Fuel Cell Solution

Hypoint proclaims, “We make zero emission air transport possible.”  They do this by, “Building a next generation hydrogen fuel cell system that can deliver

  • “Both high specific power:
    • “2,000 Watts/kilogram and high energy density
    • “1,500 Watt-hours/kilogram

Hypoint’s comparison between existing fuel cells, lithium-ion batteries and their new system

Exactly what aircraft designers are looking for.”

These numbers exceed what the best batteries can manage at this time, and according to the company’s white paper, even better performance is on the way.

Batteries vs. Fuel Cells

Hypoint proclaims, “The age of zero-emission aviation is currently being prevented by the industry’s reliance on Li-ion batteries, which have a fundamental barrier at the chemistry level.”  The firm limits cell performance to 200 Whr/kg, although Bye Aerospace claims 260 Whr/kg for their full battery packs, battery management systems and all.

Elon Musk disagrees.  CNBC reports, “Tesla co-founder and CEO Elon Musk has dismissed hydrogen fuel cells as ‘mind-bogglingly stupid,’ and that is not the only negative thing he has had to say about the technology. He has called them ‘fool cells,’ a ‘load of rubbish,’ and told Tesla shareholders at an annual meeting years ago that ‘success is simply not possible.’”

Better Performing, Hotter Fuel Cells

Obviously, the folks at Hypoint are not dissuaded by the negativity.  Perhaps most important in the newest fuel cells from Hypoint, “We are using a next-generation high temperature membrane (HTPEM) instead of a low temperature membrane (LTPEM), which increases the efficiency of a cooling system by at least 300%.”

Raising the temperature to increase cooling efficiency seems counterintuitive.  On an over-simplified level, many low-temperature fuel cells use liquid cooling to disperse heat.  That adds complications and weight, with a “traditional” LTPEM’s cooling system forming 53 percent of the fuel cell’s mass.  Hypoint’s use of HTPEMs and “turbo-cooling” them reduces the cooling system to only six percent of the total mass.  Hypoint claims a 61-percent reduction in total weight for its high-temperature fuel cells.

A Radial Arrangement

Early on, aviation pioneers attempted to lower the mass and size of engines.  The radial engine was one answer, arranging cylinder around a central crankshaft which drove the propeller.  Large cooling fins directly in the cooling blast of air helped keep temperatures in a working range.

Radial engine on the nose of a Stearman biplane. Cooling fins rely on air to dissipate heat

Hypoint has adapted this arrangement with multiple fuel cells around a central fan which forces air over the high-temperature membranes and out from each cell.  This makes for a compact arrangement similar to that of early radial engines, but with far greater efficiency.

This turbo air-cooled (TAC) power system is the first, according to Hypoint, to use both air-cooling and turbocharging.  Arranging the system in a radial fashion works well with their other material innovations.

Hypoint’s arrangement of fuel cells resembles radial engine, uses turbocharged air from central high-pressure fan to cool system

Hypoint’s specialized fuel cell bipolar plates work at 160°C (320° F) rather than the low-temperature cell’s 70° C (158° F), allowing for greater thermal efficiency.  Both are lower temperatures than those found under the cowling of any internal-combustion powerplant. Compressing the air up to three times through turbocharging results in what Hypoint claims is a 70-percent increase in the system’s available power.  Hypoint also claims an operational efficiency of 40- to 50-percent, depending “on the aircraft’s operational mode.”

Hypoint projects drive systems up to two megawatts, large enough to gang for airliners

Compact and lightweight, the system can generate power from lower-quality hydrogen, lowering operational costs.  Systems can be sized from 50 kilowatts to two megawatts, assuming a small portion of the available “real estate” within the aircraft.

Future Plans

Hypoint’s fuel cells are certain to get a thorough workout in close partner ZeroAvia’s test vehicles.  Other makers ready to offer testbeds include Piasecki Aircraft Corporation, developing a variety of unpiloted and piloted Vertical Takeoff and Landing (VTOL) aircraft; Bartini, working on a long-range eVTOL; XTI Aircraft, crafting a long-range eVTOL, and AMSL Aero Pty, an Australian company crafting a long-range air taxi.

If Hypoint fulfills its promises, many of these ambitious designs will be able to achieve their range and speed goals.  That will be good for the whole industry.

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Two Hydrogen-Powered Aerial Vehicles

Two very different hydrogen-powered aerial vehicles have come to our attention, each with a different mission, but both with endurance and range as primary functions.  Both use a fairly straightforward fuel cell/motor arrangement to power their flights.

Vicor/DMI Fuel Cell Drones

Doosan Mobility Innovation (DMI) is a major drone manufacturer, and their largest products push against the FAA’s 55-pound (24.97-kilogram) weight limit.  Their DM30, powered with a DS30 fuel cell and a 10.8 liter H2 tank weighs 21 kilograms and can carry a five kilogram (11 pound) payload.  Carrying a full payload may require using the smaller seven-liter tank.

Alessandro Mascellino, writing in EE Power, describes recent combination of resources that makes long-range drone deliveries possible.  “The first machines built as part of the collaboration can fly two hours on a single charge and have already transported masks and emergency supplies between US Virgin Islands. The drones feature a number of power components by Vicor.”

Partnering with Vicor, Doosan provides the vehicle and the power system, Vicor finesses the regulation of that power.  In the DP30 power pack, two of DMI’s fuel cells deliver a “highly variable output voltage (40 to 74 Volts).”  This Power Delivery Network (PDN) consists of two separate power trains: the first delivering 12 Amps of 48-Volt power the drone’s rotor motors, and the second providing up to eight Amps of 12-Volt power to the stack’s controller board and its cooling fans.

Vicor provides pre-regulator modulation (PRM) via its pre-regulator modulation (PRM) buck-boost regulators and a zero-voltage-switching (ZVS) buck regulator.  The PRMs, “can accept input voltages across the fuel-cell stack’s full operating range, up to its 74-V open circuit voltage (OCV), while providing a tightly regulated 48-V.”

Mascellino report,s “Looking forward, DMI plans to leverage Vicor’s modular approach to diversify product lines by power capacity, introducing other options to the 2.6kW DP30 power pack currently in production, and corresponding drones suitable for each power pack.”  Obviously planning for a range of drone sizes, DMI will produce power packs from 1.5 kW to 10 kW.

Energy density comparison between hydrogen fuel cell and lithium power. Image used courtesy of Vicor

With humanitarian and commercial missions in mind, DMI has flown between the U. S. Virgin Islands, as described above, and delivered Automated external defibrillators (AEDs) to the top of Mt. Hallasan, the tallest mountain in South Korea (1,947.06 meters or 6,388.0 ft).  This ability to haul a large payload to such an altitude is an impressive demonstration of the drone’s capability.

Delft Technical University’s Phoenix

Even longer ranges are possible with hydrogen-powered fixed wing aircraft.  Delft Technical University students are busy building a 1/3-scale model of the Phoenix motorglider they hope to demonstrate this year.  Their introduction video certainly makes that ambition seem plausible.

Before regular readers of the blog complain that the airplane looks a lot like Stuttgart University’s e-Genius, the student team credits that aircraft with inspiring the design for their craft.  In fact, e-Genius was originally Hydrogenius, as presented in 2009.  Originally designed with a range of 375 miles on 9.3 pounds of H2 (roughly equivalent to 4.2 gallons of gasoline).  That would have equaled 178.6 passenger miles per gallon, a creditable achievement.  In reality, during the 2011 NASA Green Flight Challenge sponsored by Google, the craft achieved 375.8 passenger miles per gallon.  It’s since gone on to fly with a rotary-engine range extender mounted in an underwing pod.  TU students think they can do better on hydrogen, though.

“Flying from Amsterdam to Casablanca (Morocco) on one tank of fuel? This can be done until today by not a single engine airplane!”  The roughly-translated idea of traversing 2,327 kilometers (1,446 miles) in a single hop is part of what the AeroDelft team members hope to accomplish on a fairly ambitious schedule.  First, they will fly their 1/3-scale PT this year.  Then, by 2022, a full-size, 18.6 meter span two-seater will take flight on gaseous hydrogen, followed by a liquid-fueled version 2024.

Timeline for Aerodelft’s Phoenix. PT is 1/3-scale proof-of-concept model, FS is full-size

Even the skills of a richly-talented crew are challenged by the tech required for H2 operations.  44 students from 17 countries worked on the project so far.  “The 1:3 scale prototype is powered by a 1500W fuel cell coupled with a battery pack for take-off power and safety. Hydrogen is kept in a cryogenic tank at -253°C and warmed to 0°C using a complex tubing system.  ”The tank is insulated with a 20-centimeter (7.87-inch) thick layer of material to maintain the extreme cold.

One pound of H2 will fly the model for seven hours and as many as 500 kilometers (310 miles).  Scheduled for this spring, the model will serve as a proof of concept for the full-scale aircraft.  As though 700-bar pressurized tanks and complex fueling were not enough, the craft will feature, “boundary layer suction on the wings, consisting of 14 million fine bores… on the upper side of the wing,” which could add up to 14 percent to lift coefficients.

AeroDelft’s Chief Engineer Olga Lubbers with 1/3-scale PT. Hydrogen tank for full-scale aircraft will be much smaller, proportionally

TU students hope to, “Inspire the aviation industry to act on the changes necessary to achieve a global sustainable turnaround in aviation. After two years of dedicated research and manufacturing activities, the first prototype “Phoenix PT” represents an important milestone.”

Even more ambitious, perhaps, students predict the first H2 flight around the world by 2024 and the first flight of a commercial aircraft powered by H2 by 2035.


Defeating Dendrites – Going with the Flow

One thing stalling battery development, dendrites, may have met their match if University of California at Davis researchers have their way.  Jiandi Wan’s research group allowed ions to flow through a microfluidic channel near a battery’s cathode to prevent dendrite growth.  According the group’s paper, this, “…can potentially expand the safety and lifespans of these next-generation rechargeable batteries.”  Their research may lead to safe lithium metal batteries, promising higher power and energy densities, but also struggling with safety issues.

Dendrites can grow to point where they short circuit battery and start fires

Lithium metal batteries might potentially produce twice the energy of lithium-ion batteries, but have greater risks because of the growth of tree-like dendrites on the cathode.  An article in PV Buzz explains, “When they charge, some ions are reduced to lithium metal at the cathode surface and form irregular, tree-like microstructures known as dendrites, which can eventually cause a short circuit or even an explosion.”

Associate professor Jiandi Wan’s paper in Science Advances explains the problem and the fix.  His Department of Chemical Engineering team theorized, according to PV Buzz,”…that dendrite growth is caused by the competition of mass transfer and reduction rate of lithium ions near the cathode surface. When the reduction rate of ions is much faster than the mass transfer, it creates an electroneutral gap called the space-charged layer near the cathode that contains no ions. The instability of this layer is thought to cause dendrite growth, so reducing or eliminating it might reduce dendrite growth and therefore extend the life of a battery.”

Wan’s team, by flowing ions through microchannel, suppressed dendrite growth appreeciably

The apparently uncontrolled and random deposition grows the dendrites in relation to the electrical activity, greater current seems to increase the growth.  Flowing ions through a microchannel reduced dendrite growth by up to 99 percent.   The microchannel consists of two strips of metallic foil.

The bad news – it really is not practical at this point to “directly incorporate microfluidics in real batteries.”  The Chemical Engineering research group is searching for alternative ways to “introduce local flows near the cathode surface” and eliminate the space charged layer thought to be responsible for dendrite growth.

Wan concluded, “We are quite excited to explore the new applications of our study.   We are already working on design of the cathode surface to introduce convective flows.”


Two Ways to Haul 19 on H2

Pipistel and Delft Technical University have introduced hydrogen (H2) powered, 19-seat airliners for the intermediate-range market.  Both are unique configurations with unique propulsion concepts.  Both attempt to lower drag through the use of their propulsive systems.

Pipistrel Miniliner

Pipistrel announced their Miniliner concept as a response to a “significant market potential” for a “zero-emission airplane in the 20-seat size class, capable of operating quietly from runways shorter than 1 [kilometer], including grass airstrips at small aerodromes.”  Seen as a disruptive element in providing service to currently unserved areas within a 200 to 1,000 kilometer (124 to 620 mile) range, the Miniliner could also serve as a microfeeder craft between small airports and large hubs.

Although Pipistrel is somewhat mum about the internal and powerplant details for the craft, the propeller locations seem to indicate a major effort to reduce drag and eliminate wingtip vortices.  The tail, for instance, is very much what Bruce Carmichael, a proponent of laminar-flow designs, proposed for light aircraft for decades.

A major part of MAHEPA (Modular Approach to Hybrid-Electric Propulsion Architecture) for several years, Pipistrel is also “actively performing conceptual design studies in-house, as well as partnering with universities under the also EU-funded UNIFIER19 project.”

This is the only rendering of their Miniliner Pipistrel has released, part of a quiet introduction that avoids details

Pipistrel and two project partners from Politecnico di Milano and TU Delft, “…have laid groundwork, methodology and tools for multi-objective interdisciplinary design and optimization of a brand-new near-zero-emission regional aircraft concept.”

Pipistrel is now working to overcome the “40-year-old designs, powered by fuel-burning, noisy and maintenance-intensive turboprop engines, currently in service.  They hope to be part of UNIFER’s mission of turning out zero-emission craft that will “allow for a Direct Operating Cost (DOC) reduction of 30 to 40 percent on a per-seat metric relative to today’s solutions.  Advanced flight automation technologies will “facilitate single-pilot operations.”

Trans-European Transport Network, with hub airports are indicated as white aircraft silhouette in black circles; airports capable of 20-70 passengers aircraft indicated as black aircraft silhouettes

The company sees an Entry into Service (EIS) of 2028 to 2030, without major large infrastructure investments.  With various European Union and multiple industry partners, Pipistrel foresees regulatory and operational acceptance.

Pipistrel designer Tine Tomazic explained to Flight Global that the maximum take-off weight will be around 8,500 to 9,000 kilograms (18,700 to 19,800 pounds), “slightly above the 8,618kg upper limit for CS-23 aircraft.”  He feels that good relations with regulators, made possible by the successful certification of the Velis Electro, may enable some relaxation of those limits.

Since clean hydrogen production and distribution is a growing factor in Europe, Pipistrel’s Miniliner will benefit from an increasing readiness to service fleets of 19-seat H2-powered aircraft.

Delft TU’s Greenliner

As explained on the project’s web site, “The Greenliner was designed during the Design Synthesis Exercise which is the final graduation project of the Aerospace Engineering Bachelor program at the Delft University of Technology.”  It’s rather astounding to think this was designed by 10 students in 10 weeks.  They received well-deserved high grades and the 2018 Anthony Fokker Prize from The Dutch Aerospace Foundation.

Their 134-page technical report, encompassing the range of disciplines involved, is evidence of the many overnighters they must have pulled putting the design together.

Like the Pipistrel design, the Greenliner uses liquid hydrogen stored inside the fuselage behind the passenger cabin as its fuel.  Fuel cells inside the wings produce electricity which then powers 18 propellers at the back of the fuselage.  This latter feature is part of an approach to boundary layer ingestion (BLI) which pulls the airflow over the last part of the fuselage back into the boundary layer.


The team’s report indicates use of Magnax AXF 185 motors, “[an] 8[kilogram] (15.4 pound) unit with a diameter of 185 [millimeters] (7.2 inches) and peak power output of 100 kW (136 hp).  The company is envisioning the use of these motors in everything from electric motorcycles and vehicles to electric aircraft, and even in large wind turbines when used as generators.”  This total output of 1,800 kilowatts (2,448 horsepower) gives a power loading of only 3.58 kilograms per kilowatt or 6.8 pounds per horsepower.  Compared to a Cessna 150’s 16 pounds per horsepower, this should provide excellent short-field performance and climb rates.  The Greenliner’s specs would be the equivalent of a Cessna 150 powered by 235 hp!

Clean Wings with Gurney Flaps

Greenliner’s wing is a clean design set far back on the fuselage, probably to delay interference drag, but also to compensate for those 18 motors set even further back.  This places the three-abreast passenger compartment over the wing, probably reducing trim drag for varying passenger loads.

“Valdez Cubs” regularly show up at Oshkosh to show off their STOL chops. This trailing edge shows Gurney flap

The students even applied a trick used by Valdez STOL competitors, placing a Gurney flap (named for the great racing driver) on the trailing edge and getting a boost in the lift/drag ratio.

In the video, Marco Delgado Schwartz, a member of the 10-student team that designed Greenliner, explains the reasoning behind the craft and why it is important to the future of the environment.

With a range of 925 km (575 miles), the Greenliner can cover 80 percent of all flights in regional aviation.  Its 19 passengers means it can be certified within both CS-23 or CS-25, European Union regulations that are compatible with FAA requirement.  Its maximum takeoff weight of 6,450 kilograms (14,220 pounds) enables operations from 1,500-meter (4,921-feet) runways, covering a vast majority of smaller airports.

Emitting only water vapor over their routes, these two 19-seat, H2-powered airliners will be capable of delivering passengers to formerly unserved areas and and expanding network of regional airports.  Let’s see similar plans for the U. S. infrastructure.


Joby Aviation’s eVTOL Makes a Quiet Debut

Joby Aviation’s recent debut of a very quiet eVTOL (electric Vertical Take Off and Landing) aircraft has caused a stir in the aviation and financial worlds.

Silent operation, or as near silent as possible, is essential to the future success of the sky taxi ideal.  Toward that end, JoeBen Bevirt, founder and CEO of Joby Aviation, has been working out the many aspects of  eVTOL flight for over the past decade.  Starting with kites that would generate electricity and pass it down their tethers to ground-based substations, he advanced to investigate how tilting wings and tilting rotors could safely carry passengers to their destinations.  He initially recruited a small band of engineers that’s grown to over 700 employees today and created sky taxi that’s drawn the attention of Toyota, Uber, and several venture capitalists.

Selling the Silence

Most makers of eVTOL machines promote their machines through videos that have musical soundtracks covering operational noises.  This is true even for Joby, as this recent promotional video shows.  Such soundtracks might disguise the high noise levels that would otherwise spoil the illusion of silent, effortless travel.

But in a special introduction to the aircraft by JoeBen himself, the new craft seems incredibly quiet.  JoeBen does not have to raise his voice to be heard over the downwash of the six rotors.  (Notice the swirling complexity of the sand around the landing gear).

Large propellers turning slowly is an age-old recipe for low propeller noise, and seeing antique aircraft flying verifies that.  Engine noise is the loudest part of the total sound made by many older aircraft.  As aircraft developed into faster vehicles, propeller noise became more prominent, often the loudest part of the craft’s aural signature.

Computational Fluid Dynamics (CFD) rendering of one of Alex Stoll’s earlier designs with Joby shows complexity of airflow around multiple rotors

JoeBen has been able to recruit over 700 workers in the last few years, and Alex Stoll has been with Joby from near its beginning.  Responsible for many of its approaches to translating power to thrust, his efforts stem from his 2012 Stanford dissertation on the “Design of Quiet UAV Propellers.”  The abstract to the paper notes, “Various noise-reduction techniques and their impacts on propeller performance are analyzed, and reduced tip speeds and increased blade counts are selected as most promising for the chosen conditions. Two propellers of different blade counts designed using this methodology are manufactured to validate the methodology, and static test stands are developed to perform this validation.”  His, and doubtless others’ efforts pay off in a dramatic, quiet demonstration with JoeBen calm and relatively unblown.

Such quietude will be essential in establishing city center locations for air traffic.

Success Breeds Success

Demonstrable silence and the much-patented aircraft itself have helped draw in venture capitalist, Toyota and a company called Reinvent Technology Partners, “a special purpose acquisition company from well-known investor and LinkedIn co-founder Reid Hoffman and Zynga founder Mark Pincus.”  Zynga is an on-line game service, so they may provide in-flight entertainment for Joby passengers – although that’s just conjecture on your editor’s part.

Joby and Reinvent Technologies merge through something called a SPAC, a Special Purpose Acquisition Company, seemingly an important tool in UAV/UAM financing these days.  The move allows the combined firms to “go public” and begin selling stock without going through the normal IPO, Initial Public Offering, introduction to their holdings.

The combined companies have a net worth of $6.6 billion dollars, seemingly enough to allow Joby breathing room for future development and expansion.

Reid Hoffman, co-founder of LinkedIn, explains the company’s willingness to work with what might seem to outsiders to be a risky investment.  He even describes the viewing of Joby Aviation’s machine in flight as “enchanting.”  Future travelers will be anxious to find out for themselves.