Category: Regulation

Showboating

Thinking that the pressure of global migration will go away if we build a high enough wall, physically or legally, is foolish and doesn’t work.

We have a Minister called Braveman in the UK. Currently the Home Secretary. She has a particular set of views which can accurately be described as of the right of politics. Given recent speeches it may be more accurate to say that she holds views that are of those of far-right political parties.

At a time when the UK Home Office is performing badly, she chooses to spend her time in ways that contribute little to solving problems. Her diagnosis is flawed. At the same time her desire to parade in front of cameras is insatiable. Upstaging her colleagues and showboating are roles that she plays with apparent ease. All this while the Home Office flounders.

In part Braveman’s flawed thinking comes from an overly legalistic grandstanding[1]. Yes, UK Members of Parliament are legislators, but Government Ministers should be leaders and administrators too. The UK Home Office’s challenges can not be addressed by law making alone, or even grandstanding about law making. Fine, policy can be important. In the current predicament timely action and implementation are far more important.

Building walls, forging barriers, imprisoning immigrants are appealing options to hard core isolationism, nationalists, and xenophobes. A long history of experience shows that their impacts are temporary, at best, and the worst extremes are soon entertained. North Korea has policies of that nature. History records the devastation caused by aggressive nationalists’ policies in the 1930s.

Saying that words written in the 1950s are no more relevant is a puny argument. She does not say that the Magna Carta is irrelevant or that the US Constitution is out of date. Braveman picks and chooses likes and dislikes to fit her nasty narrative[2].

At home, the cartoon of the ostrich with its head in the sand applies. Thinking that the pressure of global migration will go away if we build a high enough wall, physically or legally, is foolish and doesn’t work. Demonising those who are in peril is downright criminal.

Yes, immigration must be regulated. National borders must be controlled. A nations administration must be well managed. All of these are vital areas where immediate focus is needed. All of these seem to be ignored by Braveman.

Posturing in front of media hungry think tanks is futile. It’s for show. It’s a Trump like approach to the UK’s challenges and will bring only continued failure. Braveman has ambitions to be a party leader. That frightening prospect hangs in the air like a bad smell. Now, her unfortunate colleagues struggle and fidget when trying to defend her showboating. Let’s hope her time in office is short. 

[1] https://www.bbc.co.uk/news/uk-politics-66930930

[2] https://news.sky.com/story/suella-braverman-hits-back-at-sir-elton-john-criticism-of-speech-as-she-brushes-off-claims-she-is-aiming-for-tory-leadership-12971087

HS2 – again

Travelled on the Elizabeth Line yesterday. It was an expensive project to build. Tunnelling under London and erecting new stations was a costly business. It was called “Crossrail”. Approval was given in 2007 and construction started in 2009[1]. In 2022, one-sixth of the UK’s total rail journeys took place on the Elizabeth Line. The billions spent were a major investment in the future. Over £18 billion in fact. It was a national demonstration that huge civil engineering projects can be undertaken and mastered[2].

As a passenger the Elizabeth Line is a pleasure to use. It’s clean, speedy, and simple to use. Comparing it to the older London Tube lines is like comparing a Tesla with a Ford Anglia[3]. Sadly, a great deal of our national rail infrastructure is trapped in the Ford Anglia era.

So, what of HS2[4]? The wibbling and wobbling that has plagued the project is sucking the energy out of the resolve needed to see through an even bigger undertaking than Crossrail. Some people argue that the billions needed for HS2 could be better spent on other projects. However, the portfolio of transport projects that are suggested as alternatives never seem to materialise.

Talk of cancellations feed the political turbulence over infrastructure investments. The impression this presents goes way beyond the shores of this country. There’s no Global Britain on show here. It’s more signals of dither and lack of determination that are publicly on display. Instability and the short-term outlook is the motif of the current generation of politicians.

If there are superior and smarter alternatives to HS2 they should have come up during the planning phase of the project. What we know about vast engineering projects is that chopping and changing them midstream adds massively to costs. It also diminishes the usefulness of the outcome.

Britain needs a backbone. A rail backbone and a political backbone. The spending on HS2 is large but that spending is in country. It’s jobs and investment onshore for the benefit of the whole country, not just the Southeast of England.

The last few years have seen that banner “levelling up” heralded by Conservative politicians. This slogan will be as nothing if HS2 is wound down or constricted. The signal will be loudly heard that all that talk of levelling up the regions of Britain was shadow boxing.

In the long-term improved connectivity across the country will be a great asset. The Victorians knew a thing or two about engineering great projects. Their legacy should give us resolve.

POST: Still it is good to see the rest of the world getting on with High Speed Rail High-speed Archives – International Railway Journal (railjournal.com)

[1] https://www.timeout.com/london/news/the-new-elizabeth-line-your-crossrail-questions-answered-052322

[2] https://www.theguardian.com/uk-news/2022/mar/13/elizabeth-line-crossrail-opening-london

[3] https://www.autoexpress.co.uk/ford/104979/ford-anglia-105e-and-123e-buying-guide-and-review-1959-1968

[4] https://www.hs2.org.uk/

Upfront

Years of looking at the reliability of aircraft components and structure have given engineers a good understanding of the natural decay of mechanical workings. To that extent even electronic components are mechanical. Materials oxidise (rust), random shocks and vibration take their toll, temperatures cycles from cold to hot and back again a whole range of impacts are relentless. You can say – nothing lasts forever.

Occasionally a discovery adds to the knowledge of how materials behave under high stress. Sadly, that’s what hit the early years of civil jet aviation. The de Havilland DH106 “Comet” was the world’s first passenger carrying jet airliner. It first took to the air in 1949, which I find remarkable.

Catastrophic metal fatigue failure of the aircraft fuselage put paid to this British aviation project but only after several tragic fatal accidents. In 1954, the Comet aircraft were all grounded during an extensive accident investigation. The jets were redesigned and re-entered commercial service in 1958. However, by then the aircraft had a damaged reputation and others were doing far better. Now, those Comet aircraft that remain are museum exhibits[1].

Last week, I walked through the fuselage of a Comet 1A built in 1953 at Hatfield for Air France. It’s fascinating to see what advanced aviation technology was 70-years ago. What was surprising to me was the read across from that first version of a jet aircraft and what we have in-service now.

Automation has removed the place of the navigator and the flight engineer, but the stations of the pilot and co-pilot are familiar. The fuselage is cramped but the seating is generous and spacious. This aircraft must have been a dramatic revolution in flying at the time.

As we look to advance aviation in the coming years, with new ways of flying and new ways of powering flight so the warning of the Comet project should be heeded. We are at a time of extraordinary changes in the aviation industry. Advanced technology can deliver great benefits to society. It’s up to us to make sure we cover all the possible disbenefits as far upfront as we can. If we don’t, they will come back to bite us.

[1] https://www.dehavillandmuseum.co.uk/aircraft/de-havilland-dh106-comet-1a/

Society & Innovation

Yesterday, I drove up the main A303[1] in the stifling last summer heat. It was a windless sticky 30C. I drove past the road sign that says Micheldever Station[2]. By the way, “up” meaning heading towards London. Going “up” to London isn’t an unusual West County way of expressing that trip.

On that busy highway there are few, if any noticeable road signs that point towards a railway station. I’ve often wondered why that one was deemed so necessary. It’s not a tourist attraction, like the Watercress line[3] is in that part of the world. It’s an ordinary everyday railway station.

The small English hamlet known as Micheldever Station is a bit of an oddity. It’s the sort of place that could have been the location for The Avengers or The Saint, the popular British TV series of the 1960s. It’s in the green and pleasant countryside of Hampshire and about 10 miles north of Winchester city. An area that’s as conservative as can be.

Micheldever Station has a curious technological history. In 1895, it was the starting point for the first automobile journey in Britain. At that time a British Act of Parliament required that all self-propelled vehicles on public roads must travel at no more than 4 miles per hour and to be preceded by a man waving a red flag. In 1805, highly sensible. There’s no way that those infernal new machines should be allowed to scare the horses.

Not everyone thinks such thoughts while thundering along the A303 at 70 miles per hour. However, to me, ever since I got my first driving license at the age of 16, it’s been my most familiar of arterial roads. So, much traffic passes that way there’s never a time when it can’t be heard.

Well, we have come a long way in 138 years. Now, we are getting nervous about the safety of driverless cars, and no one even questions having a self-propelled vehicle on public owned roads. If they do, the likelihood of transforming that formula into something else is astronomically small. I can’t think of a bad time to write on the subject of: “Innovation and Its Enemies[4].” In fact, what may have graced a Victorian bookshelf can have some resonance today.

Next year, we will see commercial flights taken in electrically powered air-taxies. Without a shadow of a doubt these flights will arouse some vocal public resistance. We can take that from the history of technology. The airborne version of the man waving a red flag could raise its ugly head. I don’t say throw caution to the wind, but we need to be mindful of the natural propensity to object.

Striking a societal balance will not be easy. It would be a fool who says it will be. Slowly but surely, we will need to become accustomed to advanced new forms of mobility. Sticking a fair balance between the utility of these new machines and any burden they may place upon us will be a mighty tricky job.

I wake-up to the noise of the residential road outside. People commuting to work. The local trains send a rumble through the air. I don’t want to wake-up to the sound of an air-taxi hovering outside my window. Given the research[5] and technology under development, none of us should have to tolerate an increase in noise. Mobility and quality of life shouldn’t always be in conflict.

[1] https://youtu.be/C0sL3_NKPao

[2] https://www.southwesternrailway.com/travelling-with-us/at-the-station/micheldever

[3] https://watercressline.co.uk/

[4] https://global.oup.com/academic/product/innovation-and-its-enemies-9780190467036?cc=us&lang=en&

[5] https://ntrs.nasa.gov/citations/20210014173

RAAC

Reinforced autoclaved aerated concrete (RAAC) is making the News in the UK. An unknown number of buildings are deemed dangerous because of the aging of this material[1]. RAAC has a limited lifespan. It’s inferior to standard concrete but lightweight and low-cost at the start of its life. It was typically used in precast panels in walls, roofs and sometimes floors.

The UK Government says it has been aware of RAAC in public sector buildings, including schools, since 1994. Warnings from the Health and Safety Executive (HSE) says that RAAC could – collapse with little or no notice. This “bubbly” form of concrete can creep and deflect over time, and this can be aggravated by water penetration. So, regular inspection and maintenance are vital to keep this material safe. Especially in a country known for its inclement weather.

It’s reasonable to say there lies a problem. The public estate has been through a period of austerity. One of the first tasks to get cut back, when funds are short is regular maintenance. Now, I am making some assumptions in this respect, but they are reasonable. Public sector spending has been under significant pressure for a long time.

The other dogmatic notion that has hindered a solution to this building problem is centralisation. There was a time when local authorities managed schools. They still do but in smaller numbers. Centralised funding has decreased the power of local people to address problems with the school estate.

Aging buildings have something in common with aging structures in aviation. There’s always a demand to keep going for as long as possible. There’s always the difficulty of determining the safety margin that is acceptable. There’s always a pressure on maintenance costs.

Believe it or not aircraft structures do fail[2]. There’s a tendency to forget this source of incidents and accidents but they never go away[3]. What happens in industries where safety is a priority is investigation, feedback and learning from incidents and accidents. The aim being to ensure that there’s no repeat of known failures. Rules and regulations change to address known problems.

The vulnerability to moisture and the limited lifespan of RAAC should have been a loud wake-up call. No doubt it was for some well-managed, well-resourced enlightened organisations. Central Government has bulked at the cost of fixing this known building safety problem. A culture of delaying the fixing of difficult problems has won.

In civil aviation there’s a powerful tool called an Airworthiness Directive (AD). It’s not something that an aircraft operator can ignore or put on the back burner. The AD can mandate inspections and changes to an aircraft when an unsafe condition exists.

In the schools cases in the News, the impression is given that Government Ministers have dragged their heels and only acted at the last possible moment. Maybe the construction industry and public estate needs a strong regulator that can issue mandatory directives. Known unsafe conditions should not be left unaddressed or significantly delayed.

[1] https://www.local.gov.uk/topics/housing-and-planning/information-reinforced-autoclaved-aerated-concrete-raac

[2] https://www.faa.gov/lessons_learned/transport_airplane/accidents/N73711

[3] https://www.faa.gov/lessons_learned/transport_airplane/accidents/TC-JAV

Learn by testing

Back in the mid-1980s, aircraft system integration was part of my stock-in-trade. Project managing the integration of a safety critical system into a large new helicopter. It was a challenging but rewarding job. Rewarding in that there was a successful new aircraft at the end of the day.

For big and expensive development projects there are a great number of risks. The technical ones focus on functionality, performance, and safety. The commercial ones focus on getting the job done on-time and at a reasonable price. Project managers are in the middle of that sandwich.

Naturally, the expectations of corporate managers in the companies that take on these big challenges is that systems and equipment integration can be done to the book. Quickly and without unexpected outcomes. The practical reality is that people must be well prepared and extremely lucky not to encounter setbacks and resets. It’s not just test failures and anomalies that must be investigated and addressed. Systems integrators are working on shifting sand. The more that is known about overall aircraft flight test performance and customers preferences so technical specifications change.

With cockpit display systems, in the early days, that was often feedback from customer pilots who called for changes to the colour, size or shape of the symbology that was displayed on their screens. What can seem a simple post-flight debriefing remark could then turn into a huge change programme.

That was particularly true of safety critical software-based systems. Equipment suppliers may have advanced their design to a state where much of the expensive design validation and verification was complete. Then a system integrator comes up with a whole set of change that need to be done without additional costs and delivered super-fast. Once a flight test programme gets going it can’t be stopped without serious implications. It’s a highly dynamic situation[1].

I’m writing this blog in reaction to the news coming from Vertical Aerospace. Their VX4 prototype aircraft was involved in an flight test incident that did a lot of damage[2]. There’s no doubt this incident can provide data to feedback into the design, performance, and safety of future versions of their aircraft[3]. Integrating complex hardware and software is hard but the rewards are great.

“Excellence is never an accident. It is always the result of high intention, sincere effort, and intelligent execution.” – Aristotle

[1] https://youtu.be/Gb_eta4mZkc

[2] https://evtolinsights.com/2023/08/vertical-aerospace-identifies-propeller-as-root-cause-of-august-9-vx4-incident/

[3] https://investor.vertical-aerospace.com/news/news-details/2023/Vertical-Aerospaces-VX4-Programme-Moves-to-the-Next-Phase/default.aspx

Even more H2

There’s a couple of Hydrogen related topics that are worth a moment. One is super conductors and the other is fire.

Heavy complex equipment like the magnets for particle accelerators use superconductors[1]. When there’s space and a need for powerful magnetics, materials with special physical properties, at extreme cold temperatures find a good use.

Talk of room-temperature superconductors is far from what it seems. Such a wonderful innovation is a million miles from any practical applications, if it exists at all. There’s no theory of high-temperature superconductivity, but there’s quite a few physicists who would like to find one[2].

Aviation researchers search for high temperature superconductors for electrical propulsion with extraordinary performance is on. The likelihood of success is low, and the timeframes are very long.

When an aircraft is flying at high altitude, the cabin altitude is maintained for the safety and comfort of passengers and crew. Air compressors, valves, sensors, and controllers make sure that cabin pressure remains at equivalent to an altitude of about 8,000 feet, and lower in some cases. So, any kind of simply flammable gasses or materials inside an aircraft cabin are a definite no no. It’s a big hazard.

In flight, the positive pressure should keep leaking gas out of the cabin. That is as long as the sources of fresh air for the cabin are keep well away from potential leaks.

That’s where Hydrogen gas can present trouble. Leaks can be common in dynamic Hydrogen systems. Storage tanks must be very strong to resist pressures and insulated to keep cold, at around –250°C. Escaping H2 gas is tiny. If that’s vented overboard then the risk of explosion or fire is significantly lowered. Knowing the exact flows of liquid or gas is a must.

However, if the gas finds its way into a pressurise cabin that basic option is limited. Not only that but detecting low concentrations of the gas in the first place is mighty difficult. Its odourless but at least Hydrogen isn’t poisonous.

The big safety issue is that the gas has a very wide flammability range (4 – 70% H2 in air mixture)[3]. Yes, H2 needs a spark to ignite. A typical aircraft cabin environment will easily provide that event. Dry air and static electricity will do it even if other sources will not.

To compound difficulties, if H2 does ignite, and not explode, then its flame may not be visible to the human eye. The flame is almost colourless. Certainly, not what most people think of as a gas flame. Gas and flame detectors could be installed in aircraft cabins and baggage compartments. Audible and visual alarms could be generated but what would be the associated crew actions?

All the above requires detailed consideration in aircraft safety assessments. The move away from prescriptive regulatory requirements means each specific aircraft configuration must be addressed. There are no generic lessons to learn from past aviation accidents and incidents.

Although, I think these puzzles can be solved it’s a huge leap from here to there.

POST: Yes, Hydrogen is not for every application. Small scale aviation is better served by electrification Five Hydrogen Myths – Busted. – RMI

[1] https://home.cern/science/engineering/superconductivity

[2] https://www.science.org/doi/epdf/10.1126/science.adk2105

[3] https://h2tools.org/bestpractices/hydrogen-flames

More H2

I think this came at me both ways as a schoolboy. Both from chemistry and physics. In our 1960s chemistry lab, Bunsen burners, flasks and array of hazardous substances were the norm. Physics seemed more cerebral. Still, the hands-on side of teaching still meant some practical experimentation. That’s the part that most engrossed me.

Electrolysis starred in two mostly harmless experiments. The colourful one was about copper sulfate[1] and the other was about splitting water into its component parts. Getting Oxygen (O2) and Hydrogen (H2) gas by electrolysis[2] is mighty simple and one of those wonders of nature.

Electrolysis is a way of producing carbon-free Hydrogen from renewable and nuclear resources. Despite the apparent straightforwardness of the process, it’s quite tricky to industrialise on a large scale. One key factor to the future use of Hydrogen is getting the cost per Kg down[3].

Let’s presume that this is a solvable problem and cheap and plentiful gas supplies will be up and running by 2030. That’s not so far off given its 2023. There will surely be a market for ample supplies given the multitude of applications for Hydrogen. Will it be a global market? It needs to be.

It’s a talking point. Hydrogen fuel is one of the viable fuels for aviation. Generating power and returning it to water in the atmosphere is an attractive idea. The process meets carbon-free ambitions even if it does have lots of complications.

On average, a Boeing 737-800 uses about 5,000 lbs (2268 kg) of conventional fuel per flight hour[4]. Cryogenic Hydrogen has lower energy density. That means much more on-board fuel storage will be needed to go as far or fly as long as a current day common commercial jet aircraft.

Designing an aircraft configuration that can accommodate these facts can be done but what of the space that remains for the payload? As it does today, on-board fuel storage will need to meet stringent safety requirements.

Adding this up, it may not be the technical issues that make this difficult. Although they are difficult the technical issues can be addressed. However, will the overall package that results be economically viable? If costs are increased by a factor of, say 5, will this provide for a commercial air transport system that is like the current one?

We may have to accept that carbon-free flying reverts to the 1960s[5]. What I mean is that, instead of low-cost flights hopping here, there, and everywhere for £100, the future maybe one where long-haul flying is a relative luxury or an expensive business need.

[1] https://www.bbc.co.uk/bitesize/guides/zgn8b82/revision/3

[2] https://www.bbc.co.uk/bitesize/guides/zv2yb82/revision/1

[3] https://www.statista.com/statistics/1220812/global-hydrogen-production-cost-forecast-by-scenario/

[4] http://www.b737.org.uk/fuel.htm

[5] https://www.skyscanner.com.au/news/airlines/the-golden-age-of-plane-travel-what-flying-was-like-in-the-1950s-and-1960s-compared-to-now

ULEZ 2

It’s not the first time I’ve experienced poor air quality. It’s a wonderful city but, on certain days of the year, the air in the German city Cologne is unpleasant. It can be stagnated, stale and dirty when the weather’s hot and there’s no wind blowing.

It was compulsory. You get a fine if you don’t have one. I remember getting a green environmental badge for my car[1]. This is a scheme by which the most polluting vehicles are banned from the central city. Introduced in 2008, initially vehicles were not banned but everyone had to have a coloured badge. These were red, yellow, or green depending upon the type of vehicle. Now, only green environmental badged vehicles are permitted to enter a prescribed city zone.

Yesterday, I drove from Reigate in Surrey to Croydon. Purley Way in fact. That’s a part of the main A23 road in the London Borough of Croydon. I now wonder at my sanity in doing so. The traffic was abominable. Purley Way is a mass of shopping warehouses, tarmac, and suburban sprawl.

What’s visible is the provisions for the introduction of the Ultra Low Emission Zone (ULEZ)[2] at the end of the month. Cameras and signs. This doesn’t ban dirty vehicles from London, but it does charge them a £12.50 daily to drive into or within the ULEZ zone. 

So, here are two different approaches to addressing poor air quality. The German one doesn’t require extensive infrastructure, but it does mean additional policing. The London one is more permissive but at a price. Collecting money from polluting vehicle owners to pay for cameras, enforcement, and publicity. Both require signage to warn drivers of the zone boundaries. Both have their detractors who object to any kind of restrictions.

To me, the problem of poor air quality can not be put on the back burner. You don’t need sensors and precision measurement to know that the problem is huge, real, and persistent. Even in my small Surrey town, the marked difference between days of traffic jams and empty roads is so evident. In the middle of COVID, I walked the High Street of Reigate, and the air was as clear and fresh as a Cornish village in winter. This week, with road works underway the town has been one big traffic jam and breathing the steamy air walking the pavement is not nice. Health suffers and it’s not just the environmental damage.

The utility of the internal combustion engine has seduced our communities. Now, the balance between the benefits of driving and the freedom it once symbolised has tipped. The sheer mass of vehicles in urban environments and their daily impact is so damaging that restrictions must be mandatory. There’s no turning back.

In Cologne, these changes are particularly pertinent. It could be said that the whole ball started rolling in that city. In the district of Deutz there’s a monument to Nicolaus August Otto[3]. He was a German engineer who successfully developed the internal combustion engine.

[1] https://www.stadt-koeln.de/leben-in-koeln/klima-umwelt-tiere/luft-umweltzone/die-koelner-umweltzone

[2] https://tfl.gov.uk/modes/driving/ultra-low-emission-zone

[3] https://www.deutz.com/en/media/press-releases/125th-anniversary-of-the-death-of-nicolaus-august-otto

Electric Flight

Hype has its place. Being positive while buffeted by the inevitable ups and downs of life is purposeful and necessary. What’s not true, and might be the impression, is that electric aviation is easy. When forging ahead to build a future, that is not yet realised, there’s a need to maintain confidence. However, being blinded by the light doesn’t help when it comes to tackling difficult problems. Proof-of-concept is just that.

The big positives of electric aviation are the environmental benefits. Electric aviation is spawning many new types of aircraft and the possibilities of new types of operation. So, there’s no doubt that this is an exciting time to be an aviation enthusiast. What a great time to be in aerospace design and manufacturing. Here we are at the start of a new era[1].

My point is that high power electrics, and their control are not “simple” or intrinsically safe in ways other types of aircraft are not. I know that’s a double negative. Better I say that high power electrics, operated in a harsh airborne environment have their own complexities, especially in control and failure management. Fostering an illusion that the time between having an idea and getting it into service can be done in the blink of an eye is dangerous.

The design, development and production of advanced aircraft power distribution, control and avionics systems is not for the faint hearted. Handling large amounts of electrical power doesn’t have the outward evidence of large spinning mechanical systems but never underestimate the real power involved. Power is power.

The eVTOL aircraft in development deploy innovative design strategies. There’s a lot that’s new. Especially all together in one flying vehicle. Everyone wants fully electric and hybrid-electric aircraft with usable range and payload capacity. So, the race is one. Companies are productising the designs for electric motors of powers of greater than 10kW/kg[2] with high efficiency and impressive reliable. These systems will demand suitable care and attention when they get out into the operating world.

A 500kW motor will go up with one hell of a bang and fire when it fails. The avionics may shut it down, but everything will have to work smoothy as designed every day, not just in-flight but on the ground too. Suppressing an electrical fire isn’t the same as a conventional fuel fire either. To fix these machines the care needed will be great. 1000 Volt connections capable of supplying high power can kill.

Not wishing to be focussed on the problems but here I go. Another major problem is the number of qualified engineers, with knowledge and experience who can work in this area. The companies who know how to do this demanding work are desperately searching for new people to join their ranks.

Educators are starting to consider these demands as they plan for the future. Sadly, there’s not so many of them across the globe who are so foward looking.

The global aviation industry needs to step-up and train people like crazy. The demand for Subject Matter Experts (SMEs) is self-evident. That’s true in design, production, and maintenance. Post COVID budgets maybe stretched but without the big-time investments in people as well as machinery success will be nothing but an illusion.

POST1 : Or 150 kW motors when you have many of them going at once. Rolls-Royce Electrical Testing eVTOL Lift Motor | Aviation Week Network

POST 2: Getting ready Preparing Your Airport for Electric Aircraft and Hydrogen Technologies | The National Academies Press

[1] https://smg-consulting.com/advanced-air-mobility

[2] https://www.electricmotorengineering.com/h3x-new-investments-for-the-sustainable-aviation/