# Bjorn’s Corner: Sustainable Air Transport. Part 5. Fundamentals recap.

By Bjorn Fehrm

February 4, 2021, ©. Leeham News: We did a simple reality check on two high-profile ideas for Sustainable Air Transport last week, the Eviation Alice project and Heart Aerospace’s ES-19.

We now look at energy usage when performing Sustainable Air Transport flights, but it can be timely to recap some fundamentals of such flights before we discuss this.

Figure 1. A simplified aircraft force model. Source: Leeham Co.

##### The forces involved and how these change with mass

I’ve covered this previously, so here’s a recap. In cruise, an aircraft develops lift to counter weight and thrust to counter drag. In a steady-state, these are equal opposing forces (the model in Figure 1 is simplified but serves the purpose).

So to counter drag, we need thrust. Drag is composed of two components (if we ignore minor drags, typically less than 5% for airliners), parasitic drag (drag due to size) and induced drag (drag due to weight).

Figure 2. Drag components as a function of speed. Source: Leeham Co.

Induced drag is at highest directly after rotation and declines with speed (Figure 2). To alleviate it, we need wingspan.

Parasitic drag increases with speed, is low at rotation but high at cruise and descent. The dominant source of parasitic drag is air friction against the aircraft’s wetted area (thus it scales with size).

##### How Sustainable concepts live with drag

All air vehicles live with these forces. In an aircraft design process, a good trade between these is sought.

A troubling fact for the new concepts is the development of mass with flight time, Figure 3.

Figure 3. Aircraft mass for a 200nm flight with Battery vs. Hybrid and Fueled Commuter. Source: Leeham Co.

The figure is to scale and depicts a typical Commuter flight with nine passengers for a 200nm hop (A to B or a-b) with the typical reserves of 100nmm alternate (B to C or b-c) and 30 minutes circling at alternate (C to D, c-d with EASA turbine rules, the US FAA says 45min circling). The principle of the figure is valid for larger aircraft; it’s just the proportion of fuel as a % of the total mass that increases, and thus the amount of change of mass with time.

Mass vs. time for a battery aircraft is at max all the time, including when diverting to an alternate and circling there. The fueled aircraft takes off with less than half the mass and then burns off fuel mass during the whole flight. It lowers the drag and thus energy consumption for the later parts of the flight.

The hybrid is somewhere between these depending on the relation between battery stored energy and gas-turbine generated energy.

The aircraft designer iterates to an optimal trade for the drags by varying wingspan and area so the fueled aircraft has induced and parasitic drag in balance at the midpoint of the typical flight for the aircraft type.

As he designs a battery aircraft, he must upsize the wingarea to reach the more than double lift force at rotation and span to keep induced drag down after rotation. It results in a larger wing, resulting in a larger empennage (to control the increased moments). It increases the parasitic drag (drag due to size) and masses, thus induced drag, which requires more span, which..  . This is called the weight spiral and it’s an art to get it to stop at an optimal point.

So the conclusion is:

• A battery or hybrid aircraft is a larger, heavier aircraft with a higher drag than a fueled aircraft.
• The higher drag remains throughout the flight (batteries) or reduces slower than fueled aircraft (hybrids).
• Energy consumption is dictated by drag force times distance; thus a battery or hybrid aircraft consumes more propulsive energy than a fueled aircraft.
##### The reserves

A major problem for battery and hybrid aircraft is the required reserves for safe air transport. All pilots, my included, have had the bad stomach feeling when your planned flight energy runs tight because of a non-predicted weather change.

Therefore, the regulatory reserves are an ABSOLUTE minimum; all pilots I know add on top. The problem for heavy energy concepts is that as the weight creep hits the projects (as it always does), the only variable is cutting flight range. Reserves are untouchable and stay the same whether the aircraft has an 800, 400, or 200 nm range.

If a project has a 200nm range on the Powerpoint, it will surely have less when flying in the big windtunnel (the reality). The problem with the energy budget is that reserves grow to the flight budget’s size pretty quickly.

##### Reputed aircraft OEM tells the truth

It’s refreshing to see the honest performance summary in Figure 4 of the Tecnam company that makes the P2012 Traveller nine-seater Commuter tailored for Cape Air in Boston (left column). Together with Rolls-Royce, Tecnam projected the P-VOLT battery version of the aircraft (right column, the black % annotations are mine)). To my knowledge, it’s the first passenger battery Commuter that has reached a final specification stage from an experienced company.

I contacted the company about the reserve assumed and got a straight answer; it’s a 30 minutes VFR reserve.

Figure 4. The TECNAM P2012 in fueled and battery versions. Source: Tecnam.

The tables show the reality of where we are today and tomorrow. My conclusion is; if an IFR flight would be required, the P-VOLT is a non-starter as there is no energy for any alternate (it has to come out of the route energy, and this is tight to the point of non-usable).

##### Retrofits of existing aircraft

The above mass realities and drag trades explain why upgrading an existing fueled aircraft with battery or hybrid powertrains results in large payload and range losses. The span and structural strength are not there to compensate for any increases in mass, so the weight increase of an alternative powertrain with energy store will hit the payload.

At the end of the day, an increase in mass hits energy consumption, and it makes a hybrid consume more fuel than the design it replaces. This is only evident when every aspect is covered, and the final mass and drag bill is run in a competent flight model (or a functional prototype).

Typically after about a year or two, the projects go quiet about their initial lofty claims and then follow a total silence, or it seeps through hydrogen is studied.

##### Conclusion

We will model the energy consumption of some typical aircraft in the following Parts. I wanted to do this recap, as we can then avoid the base discussion of why the alternative aircraft consumes more energy than the ones they replace.

For those that think new, ingenious aerodynamic concepts (like multiple propellers) will fix the above, type in ePlane in the search box top right and read from Part 4. None of these concepts helps us; most tax the budget further.

Part 3 of the ePlane series describes the perhaps only propulsive change we can do which will have a positive effect; the Open Rotor. I will cover the CFM RISE project later in the series. Part 3 describes the runup work to RISE.

### 57 Comments on “Bjorn’s Corner: Sustainable Air Transport. Part 5. Fundamentals recap.”

• The problem being, this kills the main commercial advantage of flying vs other transport modes; that being speed.

• Yes, physic drive the design this way. Today for commercial aviation it gets to lock more like the NASA/Boeing Truss Brazed aircraft. We will see if there will be a short range version with electrical CFMI RISE engines with even larger fan for slower cruise speeds than the SAF/Hydrogen burning version. In theory they could integrated a 15MW electrical motor into the reduction gear without too much extra mass added if they go into the 100-400kV range and fire up the engine combustors as battery power is drained and recharge during decent enough to electrical taxi to gate.

• There is a way around the Breguet equation.
1 Operate the aircraft at extremely high altitude, say 50,000ft-100,00ft. This will eliminate parasitic drag and reduce the Cd factor thereby increasing range.
2 Further reduce parasitic drag by using very small wings or a lifting body.
3 Achieve lift by flying at very high speed. The supersonic L/D ratio of the North American XB-70 Valkyrie when in wave rider mode was around 14:1, quite good. EDF can work supersonically, in theory.
An rough analysis of a battery mass fraction of 50% with 400W.Hr/kg battery suggests that there is enough energy (mgh) to achieve the altitude required and accelerate to the supersonic speed required.

• Current generation airliners exceed an L/D of 20.
Go for the Laminar Wing that Airbus ( and others) is working on.
L/D could be increased by 40+%.
go for better propulsive efficiency : open rotor

• Laminar flow will be a big improvement but most of the drag is in the fuselage and that is hard to reduce?

Is 40% improvement in L/D equal to 1-1/1.40 ie 30% reduction in fuel burn?

• Think the Caravelle were around L/D of 20 in the late 1950’s. Today with advanced structures, flow and flutter calculations, CNC machining from 3D CAD models with ARL machines laying prepreg should achive almost sailplane performance when comparing to the resources a sailplane maker like Flugtechnik Leichtbau has. So one would expect Glide ratio of approx 50 for a new commerical airliner.

• Maybe 22 for an B787 or A350 which incorporates all of these technologies.

• numbers are for the complete airplane.
Gliders don’t have engines hanging wayward hampering the airflow 🙂

• @Uwe, nacelles not optimally located can also increase interference drag alot, but nowdays they are pretty slim and with laminar flow for quite a bit (787, A350), I think designing for M0.87 cruise speed and available gate space has a negative impact on glide ratio. It would be interesting to know the 777-9 L/D with wingtips extended at different cruise speeds/altitudes.

1. While I totally agree the logic and explanation given for the sake of an enjoyable discussion I would argue that electric propulsion has characteristics that allow electric aircraft to transcend part of the weight spiral.
For instance large numbers of responsive electric fans or propellers and their redundancy allows thrust vectoring. With relaxed stability & FBW this should allow the elimination of the long tail moment arm empennage and its significant weight and drag.
For instance the LiliumJet eVTOL is a canard. There is no need for an empennage or vertical tail. The fore-plane, unlike a horizontal tail-plane, is a positive lift producing surface rather than at negative incidence producing tail plane with a downward force and drag for no purpose other than stability.
The relatively low stability of the configuration can be removed by the Fly By Wire system and thrust vectoring. Really just an advanced yaw damper.
If we imagine the LiliumJet with its power halved and a proper undercarriage we might get an tailless eSTOL.
Also if we look at the LiliumJet we see the aircraft needs no large wing for takeoff and landing, it can operate at high wing loading or heavy undercarriage. This is another saving. These might apply to a blown wing eSTOL as well.
The strategy behind most eFlight start-ups seems to be to develop an aircraft ready in 5 years and hope that there is a big breakthrough in battery tech to make it commercially viable.
I have been following the technology of electrofuels for 24 years. My view is these will be the future. Production at efficiencies of 60%-65% seems achievable.
EVTOL is a new different market that will transcend the large infrastructure of airport and operate happily at shorter ranges. The uBer elevate White paper suggests 100 miles range is needed for commercial viability.
Elon Musk says that when batteries(Cells?) achieve a density of 400W.Hr/kg that electric flight becomes compelling. I don’t know how he did the calcs but he is also a proponent of having no control surfaces and using pure thrust vectoring Something they use on SpaceX boosters (they did end up with lattice fins for booster trajectory control)

• Most of these saving, if applied will work with fuel based aircraft, They do not have to do much with electrical power.

I think I’ve been looking too long at battery power break through to believe them. Remember speaking at a conference in SiliconV nearly 25 yrs ago..

Sure batteries get better. Pump in tens of billions: a few percent per yr.
Unlike e.g. processor power, or digital memory. Physics & safety..

• First of all a correction. The term I should have used is power vectoring not thrust vectoring (which adjusts a steerable nozzle)
In order for power vectoring to work in a relaxed stability aircraft such that it is capable of replacing an empennage we need:
1 highly responsive engines. Gas turbines have extremely poor response.
2 multiple reliable, cost efficient, maintainable engines to give the redundancy required. Again thermal engines do not meet this requirement.
We’ve just gone through the process of obsolescing 4 engine aircraft because of high maintenance costs, the higher weight of high BPR engines causing aeroelastic issues.
A tailless staggered canard or multiplane which uses power vectoring to do pitch and yaw control would be a nightmare with 6 rotax engines on each wing.

• It wasnt so much high maintenance costs that 4 engines became obscelescent ( the big fans that replaced them have very high maintenance costs too) but the scaled size had a fuel efficiency bonus which is highly desirable on long range routes.
Other features such as timing to market , ETOPS rules ,older technology came to play with A340, A380 and B747-8
The turbo prop is at the other end the smaller scale loses efficiency
faster as the compressor blades and passages become very small. Electric motors changes that

• There are also structural advantages: having the 2 engines close to the fuselage reduces aeroelastic issues(flutter etc) and lightens the wing structure. There are costs: more (larger) rudder authority is required in event of engine out on take-off. Either/or both more excess thrust or runway is the penalty.

Electric motors are essentially zero maintenance for 50,000-100,000 for the roller bearings. A simple pair of temperature sensor and a vibration sensor, integrated in the same housing, will provide an alarm if there is an problem.

Even a light aircraft could afford to have say 5 engines on each wing, say for purposes of blown wing eSTOL and thrust vectoring for yaw to reduce rudder and vert stabiliser size.

One big hope of electric flight is a large reduction in direct maintenance.

• You still have the reduced efficiency of a smaller fan/propeller. simplistic: look at aperture ( controlled airflow ) vs circumference ( aerodynamic interface disturbance)

• If you compare separate electrical motors for each prop vs. composit shafts and gearboxes with central motors at the c.g. I bet the gbx solution wins the weight race. You loose some reduncancy and individual controllability, still weight loss is really important for these UAM’s.

• The history of aviation is full of vast failures of attempts to use combining and power splitting gearboxes. Many more failures, usually spectacular, not any success. Just adding a reducer gearbox means 4 extra bearings, 5 extra grease or lubrication points (bearings plus gearbox sump) lubrication (5), temperature sensors in each bearing and the sump. Flow, pressure sensors and switches. Then there is the coupling and its serious alignment issues.

Plus lots of maintenance. The electric motor will have two bearings with temperature sensors in the bearings and windings to protect it.

Now you don’t only have a maintenance checklist, you have a pre-flight checklist.

I can think of the Heinkel He 177, might have changed the second world war for a while if its gearbox had of worked and the gearbox cut of the Atlantic supply routes, a variety of post war British engines with turbo props and Centaurus engines, the US flying flap jack.

Small electric motors have the same power to weight ratio as large. They are slightly less efficient (maybe 2% if about 75kW versus 1MW)

• You have flap and slat drive systems including shafts with small gearboxes that works pretty well. I agree they have their maintenence costs at heavy checks, but it is not a major cost. You also have the mega power F-35 lift fan drive system including a clutch designed by RR Bristol. So I claim the techology is well known and the trade off for UAM’s is not finally decided yet. One could expect the F-35B drive could be used on airliners to drive “additional fans” to increase bypass ratio when space is limited under wing.

• It’s doubtful that anyone would want to emulate any of the technology used on the F35: the plane isn’t exactly what can be called a success.

Give it a little while and see how many problems materialize with the lift fan drive system.

• And to underscore my point — here’s another, recent screw-up in an impressive list to date:
“Air Force to upgrade F-35A gas tanks to weather lightning strikes”

“In spring 2020, officials banned the F-35A from flying within 25 nautical miles of lightning or thunderstorms after finding that a crucial system may not function correctly if hit by a bolt.

“The Air Force listed the strike as a Class B mishap — one that cost between \$600,000 and \$2.5 million to repair, permanently and partially disabled someone, or sent at least three people to inpatient hospitalization. Seal said the incident is still under investigation and the final repair cost could change.

“It came about a week after lightning severely damaged two Marine Corps F-35Bs to the tune of \$570,000. No Marines were injured. The Marines Corps initially estimated the repair cost at more than \$2.5 million but later downgraded the mishap to the lower-cost Class C, Seal said.”

*********

Not exactly an attractive feature if the plane has to operate in SE Asia (with its various monsoon seasons).

• @bryce – meh to the OBIGGS issue. basically it turns out that a pipe in the system has a sympathetic resonance and cracks fairly quickly.

the repair is basically redesigning the pipe and installing the new one. unfortunately the investigation, redesign, cert & installation costs amortized over the several hundred early build F-35s that need to be retrofitted amortizes out to \$2.5m/per but for new build F-35s the cost is zero as the new part is no more expensive than the old.

would have been good to catch this and figure it out before full rate production, but it took a couple years before they started to fail.

• Those questions seem to imply some dreadful consequence that will ensue while waiting for RISE.
SAF is coming, remember?

• Yes of course, silly me, forgetting that they didn’t really mean it.
Still, if you think this is as far as this oil supply crunch is going to go, be prepared for a surprise.

• Its the purpose of Rise and not Rise.

Rise is an attempted holding action (or hi jack and other advances or more accurately Ultra) to allow GE/Safran/CFM to catch up to GTF.

Even if it happens (about as Likely as me being the US President) its 15 years away.

Its all on paper and we have seen endless open rotor or in this case Turbo Fan over and over again.

In the meantime SF and the GTF continue to advance.

• We know you don’t like — and/or don’t understand — open rotor: after all, you keep comparing it to a propellor rather than an unducted fan.
Perhaps you should leave this project to an experienced industry leader like CFM, and you can instead concentrate on simpler tech, such as cookware 😏

• @Bryce: clever reply, but it’s a personal attack. See Reader Comment rules.
Hamilton

• Sorry Scott, it may be personal, but, TW is that little grain of sand under your big toe while climbing a mountain. Or, a hemorrhoid.

• SAF is far more important than RISE at the moment but RISE and other alternative engine improvements are essential long term because SAF is likely to be more expensive.
Simple flying has a sustainability journalist and one gets all of the SAF publicity flights airlines are conducting.
We now have airlines running SAF from the following sources:
1 SAF Waste Oils
2 SAF from algae
3 Coming this year with Lufthansa (about a barrel/day) will a the first electro SAF fuel made from electracy, air and water. Much more in 2-3 years.
4 Fuels made from municipal and farm waste via bacterial fermentation intoalchols or methane and then transformation to jet fuel.
5 Fuels made from CO2 captured from blast furnace and then combined with hydrogen by bacterial to make alcohols suitable for conversion to jet fuel.
6 The elect fuels.
etc etc etc.

They key is that the public sees every airline running say 1% SAF and then sees it climb to 1.5% then 2% and so on. The SAF will rapidly become cheaper and the improvements in fuel burn may keep costs the same.

That will get the heat of. Production of SAF via electro fuels will be key to showing the public the limitations of renewables at present.

• We have precedence in BioGas development.

initially sought to refine animal husbandry wastes and getting a grip on methane ( and stink ) emmisions.

The industry has left bio wastes by the wayside
and instead concentrate on energy crops.
Devastation to the landscape. ( elsewhere look at (green stamped) palm oil production.)
We still have gigantic amounts of methane and SH2 emissions. no real gain.

I see similar issues with upcoming SAF production. Expand it enough and the climate gains will vanish.

• Hi Uwe, I understand your concerns. The regulations around SAF however make it truly sustainable. They were designed by smart people not the economic illiterates.

SAF stands for “Sustainable Aviation Fuel”. The word “Sustainable” is in there for a very deliberate reason. The fuel will not get certified (by ICAO?) unless it meets sustainability criteria. For this reason it:
1 Must not degrade the environment or land.
2 Must not compete with food crops.
SAF is thus based mainly around wastes. For instance used waste oil.

If oil seed crops are ever grown for SAF they will be special non edible oil seed plants that grow on marginal land of limited use for food crops for instance Camelina (Camelina Sativa)

We are seeing now algae based SAF (recently used by JAL and Turkish airlines)

The same mistakes made by the EU biodiesel subsidies are not being made.

The EU notoriously subsidised purchase of biofuels without guidelines and this lead to loss of rainforest habitat for the orangutan as forest was cleared for palm kernel oil.

The EU people who did this were true idiots because they were warned about the damaging distortions subsides can cause but they did it anyway. The same kind of economic illiterate ideological politician, but now sadly in Germany, is now taxing aviation fuel thereby ensuring German airlines have less money to invest in modern aircraft and can’t buy more SAF (even if the SAF component is exempt). We will see more of this foolishness.
(Incidentally though Australian born and raised I had two German parents so no insult is intended.)

At the moment German farmers are making money by growing sugar beets and throwing them into their bio digesters so that they can make biogas which is burned in internal combustion engines which is sold as electricity at a subsidised green price. This is a very wasteful use of sugar beets, wasteful use of biogas and certainly not agricultural waste.

The ICAO SAF regulations will not allow the silliness of energy crops growing on food grade land.

I suspect Lufthansas supplier of carbon offsets “AirFair” and a PtL electro fuel would probably not accept these sugar beets as a SAF input even though they would easily make jet fuel..

• In the next 10 years RISE is too far away. A new airframe is too expensive. No one can realistically introduce another airliner for 10 years. Sure a prototype can be made but what can’t be done is to replaced the manufacturing system for the B737/A320 or B787/A350. The cost of replacing the production lines and supply chain is too much. Even if it can be done it would take so long to get production rates up it would be impossible to exploit the fuel burn improvements by making enough.

I suspect the LEAP 1 and PW1100 will be improved. The PW1100G will get a improved hot section and maybe increased by pass ratio. We will see big geared turbo fans coming in towards the end of the decade.

We may see a composite wing on the A321.

Boeing may launch an aircraft I think. Maybe it can give the B737 a new wing with taller undercarriage and FBW but sounds unacceptable.

• It sounds like RISE is not just one new engine but also a final testbed for new technology like CMC, Electrical high voltage power maybe integrated into the new reduction gearbox , new compressor and turbine designs, variable pitch system for the fan vanes. One thing is to make it work per per spec, then comes massive cost and weight reductions and finally design of repair schemes

2. Has anyone looked at a battery that could, in stages, dissolve, vaporize while being contained, encapsulated, and disposed (eco-friendly) at destination. It would require staging replacements, so limited routing until infrastructure develops.
Since there isn’t much altitude/power lapse, could electric power be used as a high hot takeoff assist with the above method – a sort of 21st century JATO rack?

• No to the first one, Hydrogen while not making sense makes more sense.

There is a lot of playing around with Hybrid setup aka Prius. It works on cars well, but not on airplanes.

Ford is dropping its F-150 diesel as the combo of the V6 Eco Boost and the Hybrid kick in gives them more torque than the diesel can deliver and better fuel economy.

You might see larger trucks going that route as the diesel torque is only needed on getting going and hills.

• Would you or anyone else please explain why not beyond a simple ‘No’.
I realize it’s outside the box and I am way outside my wheelhouse, but batteries meltdown now. I was thinking of a controlled process that uses the cell’s own power. I realize there is heat and pressure involved. Maybe someone smarter than me (us?) knows the next step. I don’t mind being wrong. I was just trying to put an idea on the table.

• Actually, although he presented it in a characteristically unrefined manner, TW’s passing reference to hydrogen is the answer to your question. Viewed abstractly, hydrogen can be considered as being somewhat equivalent to an externally-stored fuel cell “electrolyte”, whose reaction products dissipate after energy production. In effect, a type of “evaporating” energy storage “battery”.

• Thank you for the explanation. I appreciate it. That still leaves my second question.
Could the hydrogen fuel cell be used to power a disappearing electric JATO rack for hot and high takeoffs, since it wouldn’t lapse much with altitude ?
BTW, I did see a Mexican 727 arrive at ORD with a JATO rack in the mid 60’s.

• JATO rack thoughts:
It would require harnessing the explosive power of hydrogen using many coordinated fuel cells, probably requiring a rocket scientist.
Not good for the fuel cell image.
Chance of certification – zero.
The JATO racked 727 was kind of cool for the 60’s.
Feel free to ignore this thread going forward.
Thanks for all of the help guys

• Hydrogen is doable because it can be made available in quantity.. There may never be enough affordable solar and wind to cover everything but hydrogen can still be made using coal, oil and natural gas with the CO2 pumped underground (old oil wells works) for sequestration storage. This blue hydrogen should only be an interim solution or a supplement to renewable green hydrogen until nuclear or whatever renewable becomes practical.

• Batteries are improving all of the time. There are several ways of protecting them.
Thermal Protection system that releases a chemical that inserts/poisons the reaction when the cell gets hot or mechanically compromised.
Microcapillaries with a wax like material that melts when parts of the cell get hot to carry away heat.
Microchips that measure temperature, voltage and current of each cells and can identify an issue and shut down the battery.
Positive temperature devices that reduces current.
These may all add weight but it’s probably 5%.
The Battery itself will need cooling and thermal and firewalls.
There are batteries which are immune to thermal runaway.
The ‘custom cells’ to be used on lilim jet can operate at 150C so it means air cooling rather than water or heat pump cooling can be used.

• There are battery systems around that hold the energy in the electrolytes: https://en.wikipedia.org/wiki/Flow_battery
One could principally imagine those being “tankered” like hydrocarbon fuels now.

At the moment these systems tend to be unwieldy.

• I made one out of a lemon, steel nail and copper wire when I was 15. It works perfectly. 1.55 volts.

• copper vs iron.
lemon juice just provides ion mobility.

3. Real aircraft builders know they hit the reserves issues and know its a non starter to not figure them in.

The California gold rush types no.

4. Its interesting to see a real aircraft company with a pretty sleek design and the 120 knots vs the Teardrop 9 Pax thing up around Everett that claims 250 knots.

Hype vs reality. That 120 was my best guess, you can trim around the margins a bit but not to the degree the Teardrop claims.

5. Electric locomotives have an overhead line. Such a thing could be very useful solving the battery problem. Over the Atlantic space based solar panels could send focused laser beams on the wings of an aircraft with high energy solar cells.

• This the sort of complete nonsense these sort of stories are trying to debunk.

• One can transmit substantial amounts of power by microwave to small aircraft. Small remotely controlled helicopters and aircraft have been powered this way. The development of AESA active array antenna and their use of gallium arsenide and silicon carbide means electrical energy can be converted to microwaves fairly efficiently. I wouldn’t think it was suitable for anything but small unmanned aircraft. It could keep a communications or remote sensing platform on station.

6. Very, very, very interesting:
“Airbus may make engines for hydrogen fuelled planes, CEO tells paper”

“Airbus (AIR) may make its own engines for its hydrogen fuelled planes, Chief Executive Officer Guillaume Faury told a German newspaper in an interview published on Saturday.
“The planemaker has said it plans to develop the world’s first zero-emission hydrogen fuelled commercial aircraft by 2035.
“Faury told the Welt am Sonntag newspaper that he could imagine equipping those aircraft with electric motors produced in-house.
“”That’s something we could basically do ourselves,” Faury was quoted as saying, speaking of a possible “change of strategy”.”

*****

Makes sense: in the age of de-coupling, it’s better not to be too dependent on others for critical parts — especially when those others are in foreign countries.

7. An ugly side of the BEV industry, which proponents prefer to keep out of the public spotlight:

“Portugal’s government approves lithium mining despite protests, concerns”

“While residents have continuously rallied against the rare metal’s mining — citing huge environmental ramifications — the country’s environment ministry has given the green light to the extraction of the “white gold” in six different parts of the country.”

https://www.euronews.com/2022/02/05/portugal-s-government-approves-lithium-mining-despite-protests-concerns

• No different to any sort of open cut mining.
It’s often the refining of the ores to concentrates that environmental concerns that are real occur.