This picture popped up in my newsfeed this month. Lord only knows why but this is what the algorithmic gods of chance thought I would be interested in. As always, when I see these things and I have 10 seconds free I will play the game of ‘find the source data’. Almost every time the source data tells a different story and most times it betrays the polar opposite to the headline graphic or story.
So if this graphic was incorrect and a good proportion of China was not undergoing ‘desertification’ then this would be another monumental lie to add to the errrrr…. monument of lies. This is the source: https://earth.org/what-is-the-great-green-wall-in-china/
As the source data is phrased and obscured with nuance and adjustments, and hard to find (it reminds me of the joke reference we used to try to use in stress reports – from books I have read…) I had to go elsewhere.
You would think that desertification would be easy to spot from aerial photographs – deserts consist of sand, non deserts consist of ‘not sand’. A landscape undergoing desertification should therefore consist of part sand and part ‘not sand’ (apologies for my simple topographical theories but I was brought up when men were real men, women were real women and small furry creatures from Alpha Centauri were real small furry creatures from Alpha Centauri. HT Douglas Adams), It follows that a landscape undergoing reverse desertification would also consist of sand and ‘not sand’ but I will give the authors of this report the benefit of the doubt and any land that I found to be trans-desert I would assume to be undergoing the change in line with the assertion of document.
Armed with my V1.0 Human Eyeball and my beta test wetware topographic recognition algorithm applicator (brain) and the excellent aerial photography library that is google earth/maps I took my first pass at an analysis of the hypothesis of the paper reference above.
Imagine my surprise when every area that I checked that was purported to be in the midst of a desertification crisis turned out to be farm land. Not only that, to my largely untrained cranial cellular learning unit a lot of the land in question looked like rice paddies. After querying my offline mobile biological relational database I discovered that rice paddies are one of the dampest things known to man, woman and men who dress as women and still call themselves Ken.
This is an image from one of the regions undergoing desertification
And here is another one
I came to the shocking conclusion that a rice paddy is not a desert and it is not likely to be one soon.
I checked the average yearly precipitation in China, and this is the first reference that popped up: https://tradingeconomics.com/china/precipitation
The powers that be are mystified why there is a steady and significant ongoing erosion of trust in the institutions that purport to represent us. It is clear that they don’t read their own publications and that there is not the most cursory checking for accuracy before these things are ejected in our direction from the data sphincters of our rulers. If an engineer who reports to me presents a piece of work directly opposed to reality in this way I would fire them on the spot.
Of course I am making the assumption that this type of document is a product of extreme yet innocent incompetence. It is easy to make a presumption of the intent to mislead, or lie as we call it in the real world. All the errors are constantly and consistently in the same direction which, I guess, could be an invisible, metaphysical force bending the incompetence of thousands of independent idiots all in one direction. Or could it be that they are mid-wits who are taking money for lying and using the internal justification of being part of a moral cause.
In the end, the reasons do not matter. Any data issued by any official body must be assumed to be incorrect. By that I mean you have to assume that it is not just erroneous but it is likely to be diametrically opposed to the truth and the opposite of the headline summary is more probable.
If you take this inverse approach you can restore reliability and integrity to the output of these government bodies. You just have to take the polar opposite to be true – give it a go and let me know how you make out.
I really don’t like to single out individual programs but this one has long been one of my favorites in terms of impracticality, complexity and sheer chutzpah.
All of what follows is nothing but my opinion with all the normal biases, probable errors and caveats.
Quick configuration level Summary The aircraft is a twin tail, high wing, canard, single engine pusher monoplane.
The wing has a moderate forward sweep and no taper, the canard has a moderate aft sweep and no taper, the twin tails are more traditional tapered and swept and have a significant outboard cant.
There is a horizontal deck between the fins aft of the cabin and the propeller.
Their Youtube channel is here Horizon Aircraft – YouTube and you can see they have a scale model flying in a hover.
General configuration summary (considering conventional forward flight only): It is unclear if any other project has ever combined a canard, a forward swept wing with a laterally spread V-tail. This raises concerns about potential undesired stability and handling characteristics that could be discovered during conventional flight testing.
The lift fans are embedded in the wing and canard. The leading and trailing edges of the wing and canard are movable so the wing can be closed up and present a clean aerodynamic surface for cruise flight.
What happens to a fixed wing aircraft when you add VTOL? When you add eVTOL to an aircraft flight envelope there are two new district phases of flight that you have to manage; hover and transition. In these two new phases of flight you have to be able to control the aircraft in a way that feels natural and logical to the pilot.
For example, aircraft control surfaces only become effective over a certain speed – for most aircraft of this class this is around 40-50knots. (vast generalization, I know)
In Hover and transition, or until you get to the aircraft stall speed in the transition configuration you will have aero or reduced effectivity from your control surfaces.
One way to remedy some of these problems is to put the tail control surfaces in the wash of the propeller, if you can get some moving air over the tail control surfaces independent of the forward velocity of the aircraft you will have pitch and yaw control and two thirds of your problems are solved.
The eagle eyed amongst you will have noticed that the Cavorite X7 with what appear to be elevators on the canard and the widely spaced canted vertical tails have kept the pitch and control surfaces well clear of useful air the propeller generates. This does not mean that they do not have pitch and yaw control in hover and transition, but that they have to design and install additional systems to achieve those same controls.
To paraphrase the redoubtable Bill Lear – the most reliable system is one that you don’t put on the aircraft.
VTOL – how is that going to work?
The total disk area does not look large.
I scaled the plan views of the aircraft and came up with a 310sqft wing area – this is very high (this will translate to a high gust response and a rough ride for the passengers at 250knots).
From this we can estimate further that the fans have a diameter roughly 2.25ft and with 12 of them a total of 47.5sqft total disk area – this gives a disk loading of 5500 / 47.5 = 115.8lb/sqft
Using one of my favorite graphs and assuming some rational partial duct efficiency you get a installed power loading of around 1.5lb/hp
This means that this aircraft will need about 5500/1.5 = 3666HP or around 2.7MW. This number does not look too far out as the AW 609, which also weighs 5500lb (AgustaWestland AW609 – Wikipedia) requires 2 x 1940HP (1.4MW) – a total of 2.8MW, approximately the same power as my scratch calculation. The AW609 looks like it has a higher rotor area and therefore a lower disk loading than the Cavorite X7 which means I am being optimistic for the X7, but lets leave it where it is.
Assuming that the ICE component of the hybrid power system is sized for cruise it follows that hovering will be done from batteries. Assuming an installed weight of 170 wh/kg and a hover of a total of one minute per flight (ignoring all reserves and go around requirements) the battery weight required is around 580lb.
If we assume each motor provides 1/12 of this power this will be 225KW per motor, assuming a motor power to weight ratio of 9KW/kg the weight of each motor will be 25kg or 55lb, as there are 12 motors the total weight of the motors will be 660lb.
If the ICE is required to provide cruise power and the aircraft will cruise at the same speed as the Piper M500 we can assume it will require roughly the same engine (this is not really true as cruise power requirement is less than takeoff power for a conventional aircraft, but the transition thrust requirement for this aircraft will be high – see later section – so we will keep the power the same as the M500) – that is a 500HP Pratt & Whitney PT6A-42A, this will have a wet installed weight of around 310lb.
The ICE engine will need a generator and a motor for the propeller, assuming the same power to weight ratio as the lift motors, the total weight of the generator and the motor for the cruise propeller will be 181lb.
I am going to add 15% of the total motor weights for power electronics and wiring.
I am guessing at the total weight of the single propeller and 12 fans to be 150lb.
Batteries
580lb
Lift Motors
660lb
Generator and Cruise motor
181lb
Power Electronics and Wiring
126lb
ICE Engine
310lb
Weight of propellers and fans (estimate)
150lb
Total
2007lb
That is 2007/5500 = 36.5% of the aircraft gross weight, this website (Horizon Aircraft Cavorite X7 (concept design)) reports the empty weight with fuel as 4001lb, assuming the empty weight without fuel is 3300lb (my guess at 700lb of fuel) the aircraft power system consumes 2007/3300 = 61% of the aircraft empty weight.
From Roskam for ‘legacy’ twin engine fixed wing aircraft of this weight class the typical proportion of the powerplant weight to gross weight is 22% to 26% – this is for piston engines. For a modern turbine single, for example the Explorer 500T (Explorer Aircraft), the weight of the installed engine and propeller is close to 10% of the aircraft MTOW.
Bear in mind that this weight assumes 1 minute of hover per flight. Considering reserves and an aborted landing/go-around capability that one minute of time could easily double or triple and the battery weight double or triple along with it…..this is ignored in the numbers above.
Also, in order for the aircraft to be safe and controllable in hover you require a thrust load above the gross weight of the aircraft, so the total available thrust should be, say 1.2 x the aircraft gross weight. This effect is also ignored.
This means that there is not enough weight in the budget for the rest of the aircraft, especially an aircraft with a wing of this size. There is at least 1000lb of mass that would usually be used for the rest of the aircraft (structures, systems, interiors) that has to be dedicated to the propulsion system. This is not a marginal problem and is a fundamental problem with this configuration. 1000lbs of mass is the equivalent of 5 passengers.
Transition – getting from vertical to horizontal I have worked on a ‘lift fan in wing’ configuration and there is one problem that you don’t realize exists until you sit down and do all the math.
In order to transition you need to get the aircraft moving through the air above its stall speed.
With the upper and lower surface of the wing disrupted by the lift fans your stall speed is higher because of the reduction in wing lift of the broken surfaces.
Because of the higher drag of the aircraft in the lift configuration you require more thrust than you would like. This drag is generated by the geometry of the broken lift surfaces but there is also a drag effect of the column(s) of lift air.
So you will have to fly faster to get to a higher stall speed than a conventional aircraft and you require more thrust to get there quickly enough to keep the battery weight even remotely bearable.
This aircraft has a very large wing for the gross weight so this will help with this problem. I assume they can close sections of the wing skins over the lift fans in sequence to slowly transition lift from fans to wing. However until a wing skin section is closed that section of wing is not really going to generate any lift. So if the LH and RH inboard wing panels close first the rest of the wing (⅔) will need to generate more direct thrust lift per motor and so the weight of the motors will be higher than noted above.
It will be interesting to see how long the aircraft takes to transition and how much forward thrust is required.
This looks to be complex enough that it will have to be controlled by software – there are too many factors to manage for a human pilot so the stability and control of the aircraft in the transitioning state (as well as dealing with failure modes) will have to be software controlled.
Software control of this type, with no consideration of any other costs, generally takes at least $100M USD to develop and certify. Because of the unique nature of this aircraft the final cost of the software could be many times the minimal estimate above.
Lots of moving parts means lots of fun!
The mechanism for the movement of the leading and trailing edges (from one of the patents) appear to be two cogs that operate on the upper surface of a track that I assume has a series of indentations to match the teeth of the cog.
Right away I can see problems and improvements here. This type of design will be particularly prone to jamming due to foreign objects (grit, for example) coming to rest in the upwards facing indentations.
This problem could be partially mitigated by moving the indentations to the lower surface of the track and placing the cog underneath. In addition, wet lubricant would have to be avoided and this could encourage foreign bodies to get stuck even with the downwards facing indentations so a dry lubricant would have to be used.
It also looks impossible to qualify this aircraft for FIKI (flight into known icing) as problems of installing an anti ice system and the potential ice accumulation on these moving surfaces preventing proper operation looks severe.
Power Loss It is not clear what will happen to the aircraft if there is a power failure during hover or transition. Let me correct that, it is very clear what will happen to the aircraft if there is a power failure during hover or transition – it will turn into an expensive non-flying brick. It is not clear what the mitigation is for the power loss scenario.
Tardis? With ICE hybrid power systems you need to provide internal volume and enclosures that satisfy installation, service and certification requirements for all the various components of the system. In addition the Cavorite X7 has no volume for fuel inside the wing. All of this stuff will have to live inside the fuselage volume – The batteries, the fuel, the ICE engine, power generation system and the power electronics. As the aircraft cruises at 250knots (Because of the large transparencies I am assuming that this aircraft is non pressurized, cruising at 250knots at below 8000ft with a wing this large is going to consume a lot of power – but that is another issue) I assume the landing gear will have to be retractable and so the landing gear also has to share this space. As do the 7 occupants.
In addition to this the liquid fuel has to be kept at, or close to the Center of gravity otherwise the excessive pitch caused by the change in fuel mass throughout the flight will require an oversize pitch trim system – and an oversize trim drag which will hurt cruise performance.
The sleek lines of the Cavorite X7 do not give much of a clue where all of this stuff (propulsion, landing gear, people) will fit.
Technical Summary So – mostly bad news.
There appear to be several ‘marginally’ viable technical aspects to this configuration. Considering the power requirements, the weight of the propulsion system is excessive for the gross weight, especially in the context of the desire to carry 7 occupants. This is a configuration that from a mass properties perspective appears to be unachievable.
The total transition sequence is over complex and the thrust power requirements are high. The requirement for software control makes this design very expensive to get to market.
There is no clear mitigation of critical failure modes such as loss of power. In addition the amount of failure modes are very large due to the number of moving surfaces and the number of lift fans. If this is all mitigated by software – yikes.
The fuselage does not appear to be designed with the necessary volume for all of the systems required for the aircraft to fulfill its advertised mission.
Companies with no product on the market making a public offering of their equity is a confidence game in the real sense of the word. The value of the company can only be based on the confidence that the company will end up being financially viable at a later date. The market is showing little confidence that there will be a successful outcome at this time.
In just a month the shares are trading at close to 15% of the original offer price. Not a stellar performance (sarc). To understand the nature of SPACs and their inherent problems this is a good article: SPACs: What You Don’t Understand Can Cost You Money
So – this program is illustrative of the eVTOL ‘boom’. It is complex, impractical and has many, many factors stacked against its eventual commercial success. Horizon has floated on the stock market and as they have not dedicated the large amount of capital and effort needed to buoy confidence on an ongoing basis (Iike Joby and Archer) they have suffered the inevitable consequence.
In order to succeed they will have to invest enormous amounts of capital in the aircraft development and certification and overcome and mitigate all of the problems inherent in their choice of configuration. They will also have to devote additional time, capital and effort into building the confidence that this is possible and they are on the path to achieve their goal.
I saw this article about the FAA hiring people with severe intellectual capabilities in my newsfeed and it came from Fox news. So as always I try to go to the source material.
You know the wheels are coming off the wagon when you read this:
Diversity is integral to achieving FAA’s mission of ensuring safe and efficient travel across our nation and beyond…….Because diversity is so critical, FAA actively supports and engages in a variety of associations, programs, coalitions and initiatives to support and accommodate employees from diverse communities and backgrounds. Our people are our strength, and we take great care in investing in and valuing them as such.
Never mind excellence and competence. Oh well, but I read on. There’s more….
Direct Hiring Authorities
The FAA utilizes Direct Hiring Authorities to provide opportunities to Veterans, individuals with disabilities or other groups that may be underrepresented or facing hardships in the current workforce. These individuals may be hired in an expedited manner upon meeting all relevant requirements. The following Direct Hiring Authorities are utilized by the FAA…
People with Severe Disabilities
For individuals with severe disabilities such as missing extremities, partial paralysis, complete paralysis, severe intellectual disability and psychiatric disability.
I have added the bold emphasis. Let me put this in engineering terms – the FAA is expediting the hiring of Stupid and Mad people.
Thankfully the FAA allow us to deep dive how they’re going to make the best use of their dynamic new staff members:
People with Disabilities
Individuals with targeted or “severe” disabilities are the most under-represented segment of the Federal workforce. The People with Disabilities Program (PWD) ensures that people with disabilities have equal Federal employment opportunities. The FAA actively recruits, hires, promotes, retains, develops and advances people with disabilities.
The FAA meets the goals of the PWD Program through a variety of practices:
Targeted Disabilities
Targeted disabilities are those disabilities that the Federal government, as a matter of policy, has identified for special emphasis in recruitment and hiring. They include hearing, vision, missing extremities, partial paralysis, complete paralysis, epilepsy, severe intellectual disability, psychiatric disability and dwarfism.
On-the-Spot Hiring
A non-competitive hiring method for filling vacancies with Veterans and/or individuals with disabilities. Managers can choose to fill an open position through the On-the-Spot hiring process given they provide the required documentation for doing so.
Expedited, on the spot, non-competitive hiring, promotion, development, advancement of Stupid and Mad people.
Just imagine – the FAA managed the thorough ruination of part 23 before this push to hire people who self identity as stupid and/or mad. What extrapolated brave new world of innovation will we be entertained with now?
Diversity means an unexpected plume of black smoke, a large number of personal tragedies and a carved granite memorial marker in some field in upstate New York that the poor bloody farmer has to plough around for the next 40 years.
It is part of the fairness based approach of adopting a representative range of safety results as we strive to generate more outcome diversity. Sometimes the aircraft lands on the runway, sometimes you get equity.
War is peace. Freedom is slavery. Ignorance is strength. Intelligence is stupidity. Sanity is Madness.
Two aspects of the world are interacting within my professional sphere. I work with very many people from a range of different backgrounds. All creeds and all races.
In one small part of the world two of these groups are at war. Actually in many parts of the world many of these groups and nationalities are at war. However, according to our glorious propaganda/industrial complex only one of them matters. It used to be Ukraine/Russia, it is now Israel/Hamas.
I am sent directly and see on social media propaganda from both sides.
So let’s get some things clear:
This is not my war
In war both sides claim moral supremacy
In war both sides blame the other side
I am sure the suffering is terrible
Life for the rest of the world goes on.
If you want my view, it does not matter who I support and who I want to win. It is not my war. Get it over with as quickly as possible and let the poor buggers on both sides get back to normal life.
If you believe we live in an age of internationalism and globalism, historical claims of indigenous status are absurd. The political establishment as a whole employs both globalism and indigeneity in an act of politically targeted emotional manipulation when it suits them. We must have open borders but we have to ignore the indigenous rights of some groups and not others based on what is the political flavor of the month. You are only indigenous if a politician allows you to be.
None of this makes sense and is used and abused as our ‘leaders’ see fit. Wars based on this are politically incoherent and politically expedient at the same time.
I am not proximal to the conflict but I am proximal to supporters of the two sides. I cannot take and should not take a side in the war but I can take sides when it comes to the supporters.
So the question comes down to which group has done the least to repel me.
Hamas attacked Israel after a prolonged, uneasy ceasefire in a conflict that has been ongoing for over 70 years, and possibly for thousands of years. I will not describe what Hamas did, if you are interested in the details of their conduct they filmed themselves and I am sure you can find the footage online.
Almost immediately cities in the west ‘protests’ started. The initial attack by Hamas on the 7th of October 2023. Israel’s invasion of Gaza started on the 28th of October 2023. There were ‘protests’ against Israel immediately afterwards, here is one from the 10th October.
As Israel’s military response had yet to start it is hard to see what they were protesting. It is hard to say these were protests at all because they look more like celebrations.
On examination of when these events happened and what was being displayed and said, these events were explicitly and obviously celebrations of the actions taken by Hamas.
Over time these organized events have transitioned from celebrations into protests as the response from Israel caused suffering in Gaza.
However at no point have I seen large scale organized celebrations of the killing of Palestinians from the other side.
The moral justice of either side’s remote cause is entirely obscured by the morals displayed by the supporters proximal to me.
Hamas ally with the most extreme left wing political factions in the west.
I see a group allying with a political faction that is openly Marxist with all of the potential for mass killings that ideology brings. They are openly and repeatedly celebrating an act of war whose only aim was to target civilians for indiscriminate killing and torture and are calling mostly implicitly but also occasionally explicitly for genocide.
The war is not proximal to me but the supporters are.
I will go further and state some more things that appear obvious to me.
The Hamas attack appeared to be specifically formulated to cause the most provocation possible to Israel, short of a nuclear, biological or chemical attack. The Hamas attack intended to create the most extreme response. It placed Israel in a political and military position where they would have little choice but to respond at the largest scale possible.
I grant Hamas the intelligence and foresight to fully understand this and I have to believe that not only was the attack intentional but the Israeli response was both predicted, expected and desired.
The allies killed 25,000 people in one night in the Dresden bombing in World War 2. At the time no-one celebrated this. The morals of war are strained and dubious at best. No movement with moral legitimacy publicly celebrates the slaughter of their enemies.
Celebrate the victory when it happens, not the barbaric acts that might eventually win you the war.
Taken from “The Second Coming”, by William Butler Yeats:
The blood-dimmed tide is loosed, and everywhere The ceremony of innocence is drowned; The best lack all conviction, while the worst Are full of passionate intensity.
It will be the best 3 minutes of time you spend today if you read the whole poem.
So having reached the end of the three chapters of the white paper here comes the inevitable conclusion section.
Please take the following as my opinion only, however that opinion is based on watching programs from the inside and the outside for the last thirty years.
It is also based on my historical research of new aerospace programs and new aerospace companies since the start of the industry. We are not shackled to the past but if we do not learn from the past we are condemned to repeat not only the mistakes but learning all the same expensive lessons over and over again.
It is always less expensive to learn from other people’s mistakes, but sometimes you only learn by making them yourself.
Here are the lowlights:
eVTOL companies violate established risk management principles of aircraft development across multiple domains.
The technology is immature, the costing is very optimistic, and the compliance landscape is only just being developed.
There is a compound technical, commercial and compliance risk that make a commercially successful introduction of a viable product to market a practical impossibility.
The problems are too varied and profound to be solvable, no matter the amount of money thrown at them.
eVTOL may represent some value to investors in the form of subsystem IP that may be useful at a later stage in the evolution of UAM or a brand with public recognition.
A return on investment is very, very unlikely.
Traditional aerospace OEM startups suffer from borderline commercial viability without adopting these specific eVTOL multiple critical risk factors.
Adoption of additional enormous irreconcilable risks do not make success more likely. Raising more money does not reduce the risk, it just increases the financial burden on the corporation and gives you the false impression that you have the ability to solve your technical, commercial and compliance problems.
J. R. R. Tolkien: “False hopes are more dangerous than fears.”
Historically successful aircraft startups come to market with the simplest possible product. Starting out with a very complex product as your first project has never been a recipe for success.
We are very grateful to the people who have donated to the technical library over the years. The cost to keep it going is significant and we appreciate every contribution no matter how small.
However, donating is difficult as you are making a cash gift for nothing tangible in return (OK, you get some stuff from the website, but there is a tenuous physical relationship there….)
In order to make it easier for people to support the technical library we have moved from asking for donations to selling engineering related products. You can see what we have on offer here.
Our intent is to make the designs relevant to engineers, unique and amusing where we can.
I have ordered some of the products as samples and I am happy with the quality and the value and am going to treat myself to a number of the ‘bad patent’ t-shirts and sweaters.
We will be updating the range of merchandise and the designs so please do check out the store on a regular basis and if you can make your engineering colleagues and friends aware I am sure they will find something that will amuse and delight them.
As with most business activities, the 2000lb (907.185kg) elephant in the room is the government.
The government has three major impacts across multiple markets in different ways.
These impacts are unique to eVTOL as they are new and unique products. As such they require new regulatory approaches in product certification, operation and pilot licensing. Aircraft that are certified under existing airworthiness regulations (part 23 or part 27) can use existing regulations and avoid almost all compliance risks.
Product Certification Every aircraft must be qualified to a set of product-related regulations that define the design details, reliability and standards of safety that must be inherent in the design of the aircraft.
For eVTOL, these standards are completely new. Not only are they completely new, but they are different across different jurisdictions. In Europe, there is a different set of standards to the standards used in North America. This causes significant difficulties for products developed in Europe gaining exports to North America and products developed in North America gaining exports to Europe.
This is unlike existing regulations for fixed-wing and rotary-wing aircraft which are almost completely harmonized across all jurisdictions across the world. eVTOL regulations are new and unharmonized.
Using existing and time-tested regulations also removes the safety risk of immature regulations. The current regulations have been reformed over time, through repeated updates and amendments spurred by repeated incidents and tragedies. With a completely new set of regulatory standards, these incidents and tragedies have yet to occur, but they inevitably will.
The higher safety risk of using an immature set of regulations will be reflected in a higher incident rate and a higher insurance cost.
Another effect of using new sets of regulations is the eVTOL developers must develop new methods of compliance for these new regulations. This.is very time-consuming and very expensive. It can be seen from the difference in the projected time to market and the actual time to market of almost all eVTOL programs. This effect on schedule and budget has been consistently underestimated by eVTOL developers.
For example, Joby started their program in 2009. It was only in the last year (2022) that they achieved approval for their first compliance plan, the official description of their means of compliance. Having an approved compliance plan means that you can start your compliance activities. 2009-2022, 13 years is a long time to get to an approved compliance plan. This is reflected in the amount of money ($2bn USD) that Joby has raised to get to this stage of their program.
When a program completes a part of its demonstration of compliance, it then must find someone at the regulator or an individual with delegated responsibility, who will sign off on a finding of compliance against a completely new set of regulations via a completely new means of compliance. This will be a challenge. eVTOL OEMs may have discarded risk aversion, but the regulator and delegated individuals will be less accepting of risk.
Achieving eVTOL-type certification has proven to be and will continue to be excessively time-consuming and expensive.
Operational Certification Once a company completes the product certification process, they must put their aircraft into commercial or private operation. This involves complying with a set of operational standards. These standards are also new, or they are adapted from existing standards for conventional aircraft operation.
eVTOL operational standards like product certification standards are not harmonized across international jurisdictions. The FAA in America and EASA in Europe have developed different operational standards for these types of vehicles. Some aspects of the design of the vehicle are driven by compliance with the operational standards. Because of this, intrinsic aspects of the vehicles may create a barrier to export between two major markets. Designs will require significant changes and re-certification to achieve export sales and foreign operations.
A further problem created by operational certification is any regulator may decide that a very conservative approach is required. For example, the FAA has taken the reserve requirements from part 29 large rotorcraft of forty-five minutes for IFR (Instrument Flight Rules) operation and applied that reserve requirement to what they call powered lift category aircraft, or eVTOL. Battery-driven aircraft have relatively low endurance and applying a very high reserve requirement to them will severely degrade commercial viability.
It is worth noting that the FAA operational regulations consist of over 137,000 words, while EASA has opted to consider UAVs and UAM in the same category and has issued an NPA that consists of over 118,000 words.
Every OEM who wants to sell their product in the North American and European markets will have to read, understand, compare, reconcile and demonstrate compliance with these hundreds of thousands of words of differing regulatory standards.
If designing a single vehicle to meet these two different sets of requirements is at all possible it is expensive and onerous. This places additional and unique demands on an aircraft type whose performance is already compromised by the immature technology and low energy density of the chosen energy storage medium.
Pilot Training and Availability The status of pilot qualification has only recently beeen addressed by the regulators. Different eVTOL aircraft have different modes of operation, different flight control software systems creating different pilot feel and different pilot interfaces. In this context, pilot training and qualification is a non-trivial task.
Comparing the difference in pilot interfaces between leading eVTOL projects some of the problems can be seen.
There are two main layout types – ‘single seat two sticks’ and the ‘two seats one stick’.
Joby type Cockpit, two control sticks, single cockpit seat – no space for pilot trainer in cockpit. Layout similar to Lilium, Vertical and Archer
Volocopter type Cockpit, single stick for the pilot’s right hand, space for pilot trainer in RH seat. The layout is similar to Ehang.
Both pilot interfaces are different to conventional fixed wing and helicopter controls, and they are different to each other.
This creates a problem of transferring pilot qualifications from conventional aircraft to eVTOL and between eVTOL types.
Each new pilot qualification for each new type of vehicle will need definition and international harmonization. It will take many years to reach international agreement on the standards and training requirements for private and commercial pilot licenses.
The cost of qualifying as a pilot able to fly commercial service is at least $50,000. The total projected number of eVTOL aircraft in service by 2030 by the OEMs is in the tens of thousands. (In contrast McKinsey estimates the total number in 2030 number to be 1000).
Taking the OEM figures and placing a cap of 10,000 aircraft in service by 2030 the total cost of pilot training will be $500,000,000.
A commercial pilot for existing aircraft types requires about 250 hours flying time. For 10,000 pilots this equates to 2.5M flying hours. If pilot training starts in 2025 and is split over 5 years up to 2030, this is an average of 2000 pilots and 500,000 flying hours per year. We can reasonably estimate that each training or personal aircraft is flown 4 hours per day and is operating 200 days per year. To train the required number of pilots over 5 years 625 eVTOL aircraft will have to be dedicated solely to that task.
There will have to be pilot training instructors, simulators and training facilities made available. There is no indication that the investment is being made at this time, or if investment will be made to support the eVTOL OEM timeline for the number of pilots necessary to support production projections.
Compliance Summary Compared with an equivalent aircraft which is certified and operated under existing regulatory standards, an eVTOL aircraft faces an array of delays and problems.
It is not known if there is a route through type and operations certification that can result in a viable aircraft product.
The pilot qualification route is not defined and the infrastructure is not available to create the numbers of pilots necessary to allow commercial operation of eVTOL at a scale necessary to support OEM business models.
What does this mean? As Rolls Royce is a business and we can assume that they run their business on a rational basis, they have assessed that the risk vs reward balance is negative.
It is negative to such an extent that they are willing to write off the purchase of the business from Siemens and the money that they have invested since the acquisition.
How did the markets react over the last 4 days?
It is early days yet but I would say that in the short term the markets agree.
The advice I have received from within eVTOL startups from the most competent people I know is that you have to develop all of these new technologies in-house.
This is what Pipstrel did with the Velis powertrain and it was the right thing to do.
I am not saying Rolls Royce is particularly bad, but they clearly have a risk tolerance lower than other engine manufacturers. Every risky startup assumes that a risk sharing partner is in the program with them for the long term. When you bring in suppliers who are many times your size, they have a level of acceptable risk. That acceptable risk is always lower than yours. They can walk away from the program at any time if their risk assessment changes, or the rest of their business outlook changes.
As a startup with a single product you are in a do or die situation. Every large supplier you bring into the program is not. For them it is less of ‘do or die’, more of ‘yawn, meh, what do the business analysts say?’ situation.
Startup companies developing new technology can share the risk with larger suppliers but they cannot share the risk tolerance.
You can outsource commodity items and services – seats, sheet metal fabrication, interior liners, wheel, tires, etc.
You can never outsource risk, and indeed, you never should. A supplier’s appetite to accept your risk is always going to be a fraction of your own.
You will have to raise the capital and develop the technology in house. Vertically integrate. There is a reason that in the early years of aviation many aircraft OEMs developed their own engines.
Ironically Rolls Royce was one of the first non aircraft manufacturers to make an aircraft engine (https://en.wikipedia.org/wiki/Rolls-Royce_Limited). In 1914 and only at the request of the British government.
There are external suppliers left in the AAM electric powertrain field. How much appetite for risk do they have compared to Rolls Royce? Will they have the appetite for risk to maintain their involvement in this sector? For how long?
One should not conclude that Advanced Air Mobility has no future. But we can conclude that it was a mistake to take on large, risk averse partners as partners on new technology projects.
If you want to develop an aircraft that depends on a new technology, develop the new technology first.
Pipstrel did.
If you design your own motor you will have an easier set of boundary conditions to meet than a larger risk sharing partner who will want the product to meet a wider range of applications to maximize revenue potential.
If I were a eVTOL developer with a risk sharing partner developing the electric powertrain I would be nervous. I would set up an in-house development group, get the best people, give them a difficult mission with a small budget. If Pipistrel did it, you can too.
Commercial The commercial risk is anchored on the MaaS (Mobility as a Service) business model that almost every eVTOL company relies on for commercial justification for their product.
The Market Sales of the aircraft and the commercial success of the venture are related directly to the market for the service the aircraft creates. The market for the service is related to the relative cost of that service compared to the available alternatives.
To observe the obvious, the higher the cost of the mobility service provided by an eVTOL aircraft the less competitive it is, the lower the demand for that service will be and the lower the demand will be for the aircraft.
The number of aircraft you can sell, or rather the rate at which you can manufacture and sell them directly affects the cost of manufacture. The lower the rate of manufacture the higher the unit cost of manufacture. This is the classic ‘economy of scale’ phenomenon.
If demand for a product dictates that a company manufactures at a lower rate than planned, not only do they suffer a reduced revenue but they suffer a reduced margin.
This is a classic problem for aerospace OEM startups. They reach the market only to find that the demand is not what was projected. The worst case is that the cost of manufacture at the realized lower rate of manufacture is so high that a loss is made on each aircraft. Despite all the time and resources spent to get to market, and despite the excellence of the product, the company will fail after crossing the finish line. There are multiple examples of this outcome, the most notable are Sino Sweringen and Eclipse. Coincidentally, both programs spent a relatively very large amount of money to reach the general aviation market. In 2023 US dollars Sino Swearingen spent over $1.5BN and Eclipse over $2.5BN.
There are several limitations to the competitiveness of eVTOL MaaS. eVTOL aircraft are flying in the same environment as any other aircraft ‘on demand’ service and aircraft design has a limited effect on total aircraft operating economics compared to a conventional alternative. Some costs (insurance, landing fees, crew, etc.) will remain the same or will be higher than conventional alternatives.
The projection of eVTOL operating costs varies, but the approach defined by Robert Mann appears to be universally adopted:
“You can’t sell any of this stuff if you don’t make optimistic projections,” said Robert Mann… R.W. Mann & Company
Mobility Analyst, Asad Hussein writes: “Air taxi startup Lilium has claimed that the cost of a trip from Manhattan to JFK Airport could be $70, or approximately $4.40 per mile. Joby Aviation estimates the operating cost of its aircraft will be $3.80 per mile for a 25-mile trip, significantly below the cost of a $9-per-mile helicopter trip.”
A study commissioned by NASA and carried out by Booz Allen Hamilton obtained the following results:
The results of their study show that an eVTOL aircraft only becomes competitive with a 5-passenger helicopter with (5 occupants) when it carries 4 passengers.
This reveals a small but potentially significant cost saving for operators. This saving is far less than the eVTOL operators claim, making truth of the statement by Robert Mann above.
The same Booz Allen Hamilton report pointed out that up to 60% of further cost savings were possible for eVTOL with autonomy (pilotless flight) and ‘technological improvements’. No timetable for the adoption of these measures was made.
The criticality of projected economies of scale on eVTOL OEM business models cannot be overstated. Archer Aviation has made their investor deck publicly available and their volume production rate is mentioned on slide 44 as >5000 per year, although this is tempered on slide 47 as 2300 per year by 2030. To put this in context, GAMA (General Aviation Manufacturers Association) give global sale records of aircraft types. In 2022 a total of 932 helicopters were sold.
Archer’s business model requires that they sell nearly 2.5 times the entire global 2022 annual helicopter market in 2030.
The over optimistic projection of aircraft demand and production numbers creates a vast overestimation of production rates and reliance on unrealistically low production costs. The reality of higher aircraft operating costs, lower aircraft demand, lower production numbers and higher unit costs in manufacture will sharply contradict the optimistic business models. Company revenue will be reduced by at least one order of magnitude and the profit margin on each unit will disappear.
Reliability & MRO The operating economics of leading eVTOLs rely on aircraft being operated at a very high number of hours per year.
The value used by the FAA for systems safety analysis for large (part 25) commercial aviation is an average use of 3000 hours per year. It is not credible that aircraft operating over much shorter legs can exceed, equal or approach that value.
If eVTOL aircraft are to attempt to reach very high usage rates, the aircraft must have a very high dispatch readiness.
High dispatch readiness is related to both overall aircraft reliability and the ability to rectify, repair and replace whatever is needed to solve problems that arise and quickly return the aircraft to service.
Reliability Aircraft electrical drive systems are often promoted as being more reliable than piston or turbine engine systems because they have fewer moving parts.
This is true (although turbine engines have surprisingly few moving parts) but has yet to be demonstrated.
A statement that is more likely to be true would be something like this. “When aircraft electrical powertrains are fully mature and all common service issues are understood and mitigations and resolutions fully developed there is a very good chance that they will prove more reliable than existing piston and turbine engines.”
The inherent theoretical reliability of a system is only one component of real-life reliability. When aircraft electrical powertrains are first used in service it would be rational to assume that they will be as reliable or less reliable than existing aircraft powertrains.
The potential increase in reliability can be realized over time with experience. We will only understand what this learning curve looks like after the fact.
The same can be said of the software control systems that these aircraft rely on to remain airborne. Development simulations and flight tests cover a subset of combined service conditions, vehicle states and pilot inputs when compared to what may happen in real life.
When these vehicles are first introduced into service the complexity and chaos of real operational conditions will be imposed on the control software. The limitations of the software will be revealed, airworthiness will be affected, and remedies will be required. It should be expected that Airworthiness Directives will be issued as a result and these vehicles will face restrictions and limitations or even grounding for some time.
These likely reliability risks apply just as much to any other component of new technology employed in these vehicles. Unique glass cockpits, control systems servo motors, sensors, et al.
MRO The supply chain for LRUs (Line Replaceable Units) for conventional aircraft has consolidated over decades to the point where there is a commonality of suppliers and components between multiple aircraft manufacturers and aircraft models.
Commonly used aircraft vendor components are kept in stock at MRO centres all over the world and are available in minutes, replacement can occur, and the aircraft returned to service quickly.
This requirement to minimize time out of service typically drives new aircraft to consider the inclusion of as many existing vendor components for their aircraft as possible. There may be a small performance penalty to pay but it has a disproportionate effect on serviceability.
If there is an entirely new class of aircraft and each aircraft in that class employs a set of unique components that are unique only to that model of aircraft, the number of new components that may require replacement, repair or servicing will impose an excessive burden on the capabilities of an MRO organization.
If a set of unique components is required by only one aircraft type out of tens or hundreds of models of aircraft that an MRO centre serves, it is not economical to invest in the inventory and dedicate the warehouse space to keep these items in stock.
These aspects can delay the resolution of aircraft problems to the extent that the minutes required to get an aircraft back into service can extend to days or weeks.
Training the maintenance technicians on correct storage, handling, installation, and quality checking of the new components is a further challenge that must be addressed.
If multiple eVTOL aircraft are brought to market within a short time frame, each with a unique set of new LRUs, at best there will be a lag for MRO operations to catch up. At worst eVTOL may suffer in the longer term until their electrical system and drive components consolidate to the point where broad commonality makes local warehousing practical and enables timely MRO support. This may take decades.
Other Commercial Issues
Insurance The insurability/cost of insurance for eVTOL aircraft is unknown. The risk of a new aircraft type based on new technology will be represented as a comparatively high cost of insurance.
Landing fees The investment necessary to create the vertiport infrastructure for high volume eVTOL deployment will have to be recovered by levying landing fees for the users of the facilities. Landing fees are projected to be as high as $300 per passenger.
Residual Value The appeal of eVTOL aircraft to fleet operators will be affected by the residual value of the product. This is another unknown. The residual value of electric cars may indicate that optimism is not warranted.
Market Acceptance and Customer Psychology A high utilization rate presupposes a high market acceptance amongst potential users. Fear of flying is a problem that can affect a significant proportion of the population:
Between 33% and 40% of all people experience some form of anxiety when it comes to flying.
60% of sufferers experience generalized anxiety during the flight (and leading up to it) that they can easily manage on their own.
Between 2.5% and 5% of the population have crippling anxiety, a genuine fear of flying that is classified as a clinical phobia.
People report their first fear of flying “attack” at the age of 27 on average.
The introduction of a new, small type of aircraft will receive a greater than average phobic response and this will reduce the size of the available market for commercial operations.
Orders Orders with deposits are the greatest indication of demand from operators and confirmation of the commercial viability of the aircraft product. The proportion of overall eVTOL orders that are ‘firm’ is very low.
“While orders represent an important signal of demand, most of them are conditional, non-firm and not requiring any deposits, essentially allowing the operators to walk away from the deals.”
The lack of firm orders from eVTOL signals a lack of confidence from commercial operators.
Commercial Summary The commercial case for eVTOL rests on very high utilization rates. It is incorrect to assume that eVTOL will achieve higher utilization rates than existing aircraft types in similar operations. Low initial reliability and low LRU availability will have a profound negative effect on utilization.
Commercial viability is also likely to be negatively affected by insurance costs, higher than projected landing fees and customer acceptance.
Unknown residual value will make fleet purchasers reluctant to invest in an asset of uncertain value.
A negative commercial outlook is confirmed by the lack of firm orders for eVTOLs.
One of our readers sent me a note after the last newsletter suggesting that I write a piece on AI.
My experience of using AI is relatively limited. I use it to generate artwork, logos, and occasionally for graphic design. I also use it to assist with writing, but in a minor capacity, primarily for grammar and sentence structure suggestions. For instance, I am currently dictating this article to my computer. The way it appears on the screen suggests that there is some relatively advanced real-time processing involved in interpreting my vocalizations and transforming them into coherent English text. I am certain that AI plays a role in this process.
If you have used Chat GPT or Google Bard or any other web based AI. You will have found that it’s like a very fancy search engine. You can ask it a question and it goes and looks at the web and rather than bringing back a set of URLs, websites that may contain the information you’re looking for, it goes to those sites itself and tries to collate the information and presents it as a piece of language in standard English for me, maybe Hindi for you or Japanese.
This is slightly problematic – it represents the results of searching the web as a piece of writing that purports (in terms of its own internal language) to be entirely factual. However, it often is not. When you get a series of URLs in response to your enquiry, you need to apply the appropriate degree of skepticism based on the source and your own knowledge and instincts.
Regardless, this is an interesting use of AI. If we project this forward and the AI algorithms become better at distinguishing fact from error, or phrasing its language to present subjective opinions in the correct context, websites will become meaningless. AI will be able to tell you exactly what you want to know without having to refer you to a website and forcing you to go through the tedious process of clicking on a link and then reading through the website to find the specific information you desire.
Of course, this would completely change the way that we use the Internet and the way we post information. All attribution, branding, and value would be conferred entirely to the AI and not to the source material. This will be problematic as people will stop posting things online, as there will be no point, no credit for doing so, and no potential advertising revenue. The AI bot will have less and less contemporary and relevant information to select from as people stop posting information. There will be some limits placed on AI, and a happy medium will likely be reached.
If you’ve ever tried to use AI in any form, it is very impressive, but its behavior is that of an autistic savant. As an engineer, I empathize with that type of personality, and I’ve worked with many of them, and I am one myself. So, for me, using AI is a relatively naturalistic approach to assembling information.
So what does language AI do?
It does something like this:
There follows ten rewrites of the simple phrase: The dog jumps over the cat. The results of the AI rewrite is used as the input of the next rewrite:
The cat is effortlessly leaped over by the dog as it gracefully jumps through the air.
The dog gracefully jumps through the air, effortlessly leaping over the cat.
The cat gazes in awe as the dog effortlessly soars through the air, displaying its graceful agility and leaping over with ease.
As the cat looks on, it is filled with amazement as the dog effortlessly takes flight, showcasing its exquisite agility and effortlessly clearing the obstacle in its path.
As the feline gazes intently, its eyes widen with astonishment as the canine gracefully soars through the air, revealing its remarkable nimbleness and effortlessly soaring over the hurdle obstructing its way.
As the feline fixates its gaze, its eyes widen in sheer astonishment, witnessing the canine’s elegant flight through the air. The dog’s exceptional agility becomes evident as it effortlessly clears the obstacle blocking its path, leaving the feline in awe.
As the feline becomes fixated, its eyes widen in sheer astonishment, observing the canine’s graceful mid-air glide. The dog’s exceptional agility is unmistakable as it effortlessly overcomes the obstacle obstructing its way, leaving the feline in a state of awe.
In a captivating spectacle, the feline finds itself utterly transfixed, its eyes widening in sheer astonishment. It stands witness to the canine’s mesmerizing mid-air glide, and its exceptional agility is unmistakable. With effortless grace, the dog effortlessly conquers the obstacle that had impeded its path, thus leaving the feline in a state of awe.
The feline becomes completely engrossed, as if under a spell, when it witnesses the captivating spectacle before its eyes. The feline’s eyes widen in sheer astonishment, unable to look away from the canine’s mesmerizing mid-air glide. The canine’s exceptional agility is unmistakable as it effortlessly conquers the obstacle that once hindered its path. With graceful and effortless movements, the dog leaves the feline in a state of awe.
The feline is instantly captivated, almost entranced, by the mesmerizing spectacle unfolding before its eyes. Its eyes widen in sheer astonishment as it becomes utterly unable to tear its gaze away from the canine’s enchanting mid-air glide. The canine’s impressive agility is undeniable, effortlessly overcoming the obstacle that once obstructed its path. With graceful and seemingly effortless movements, the dog leaves the feline in a state of pure awe.
And this is using the same AI to shorten number 10 to a 10 letter phrase
Feline captivated, eyes widened, unable to tear gaze from enchanting canine.
AI, in its freely available form, is good at expanding non deterministic interpretation. It can add complexity in the correct syntax, but any meaning that it adds is both accidental and incidental.
It is much worse at determining the essence of a concept.
From The dog jumps over the cat to Feline captivated, eyes widened, unable to tear gaze from enchanting canine.
It can add complexity and the meaning is generally maintained but in removing complexity the meaning can be lost.
As a process it appears to be creative but it is really entropic as the created material is just the same material spread over a wider area. The total energy level is maintained but not increased.
Is AI going to take your job?
Well, it depends. AI cannot be trusted to tell the truth. If you are a journalist or a politician, I would start to get nervous about future employment prospects.
For the rest of us – as long as you are taking real responsibility for your work then AI will not be replacing you. AI should be not making decisions now, and even if it improves it cannot be held accountable or liable.
This is similar to the problem with autonomous flight. It may be theoretically possible and it may even be safer. However mistakes will happen and people will get hurt and killed. Without pilot error as a liability shield the software OEM becomes responsible for all negative outcomes. This does not end well for the OEM.
If we allow an AI to make decisions the OEM of the AI will face a similar problem.
AI may eventually take the role of a virtual team member, but until we revise our societal legal accountability standards the role of AI in decision making will be advisory only.
What does this mean?
For now we have a useful tool we have not yet learned how to fully exploit so spend time getting familiar with the tool. I would advise not reading too much into the implications for now. It is very hard to predict anything – especially the future.
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