A version of this article first appeared in the August 2019 edition of our free newsletter, to subscribe click here

Over a year ago we published a white paper. This white paper was an attempt to codify a method for risk assessment method for aerial urban mobility development projects.

We made this assessment, and the accompanying spreadsheet tool, to try to make sense of the multiple configurations that are in play and make an honest attempt to determine which would have a chance of becoming an archetypal product: A product that would be a commercial success and define the market. The DGI Phantom of the manned urban mobility world..

One year on and the field of battle looks similar. Some projects have departed the field and some new contenders have entered the fray. Many are still diligently working away improving their concepts, looking for investment and building prototypes..

We have used our risk assessment spreadsheet tool to create a ranking chart for the projects currently in play.

These risk assessment scores are purely for civil certification and the manned civil marketplace. These designs may fare much better, or much worse as military or unmanned vehicles, these aspects have not been included in this assessment.

Also note that the assessment is based on two aspects only. Certification risk and market risk.

These two factors are judged to be the two most significant factors in the commercial success of an aircraft project – assuming technological feasibility.

The duration of the certification program is the greatest cost driver for the program. The more unique and complex the concept, the longer it will take to shephard through certification and the greater the overall development cost will be.

Market acceptance is the greatest driver for revenue (assuming you reach the market) and historically, the aircraft market has been famously conservative.

Program success and risk is entirely predicated on the potential of making a profit for the investors.

The more exotic the design the longer it will take to get through the certification process (e.g. AW609 tilt rotor) the greater the cost will be, and the greater market resistance when it finally gets there, no matter how great it looks (e.g. Piaggio Avanti).

High development costs and low sales – bad

Low development costs and high sales – good

That may come across as patronizing, but it is surprising how many projects lose sight of these fundamentals.

Any Innovation introduces these factors and risks. They have to be acknowledged, measured (if possible) and managed.

Some important notes:

• If you are connected to a project in the chart and you disagree with the ranking you have received, please download and read the white paper that defines the methodology, if you want to know how I have applied the scoring system feel free to contact me. I will not change the rankings but I will explain the outcome to you.
• Just because something is possible to make and fly it does not mean that it is affordable to get it through the certification process or that anyone will buy it.
• Just because a project has 10,000 advance orders it does not mean it will make it through certification and reach the market.
• And just because a project achieves type certification and has 10,000 orders  it does not mean that they will sell at a high enough margin to make a profit.
• The ranking given in this study may have some correlation to projects that succeed. However, the devil lives in the details and the execution of a project is critical, therefore the results of this study are idealized and simplistic
• We applaud anyone who has the initiative to design, make and fly a unique air vehicle and go through the hard work of chasing investment. It is a difficult, risky, all consuming pursuit and all of you are doing your best to advance the industry and improve lives. We wish all of you success. The rankings are a measure of relative potential success. This is not an absolute measure – all may fail or all may succeed…..and of course we could be completely wrong.
• I have had informal communication and commercial relationships with many of the projects or people involved in these projects. I have tried my best to remove my personal bias or hopes from the assessments made to create the rankings. Where I have had an advisory or technical relationship with any particular project I will highlight it where relevant

Data

The projects and some of the data has been taken from the excellent http://evtol.news website. It must be made clear that evtol.news have no part in generating these rankings and I have only used them as a very useful resource.

As per the http://evtol.news website I have broken down the projects into the following categories:

Vectored Thrust

An eVTOL aircraft that uses any of its thrusters for lift and cruise.

Lift + Cruise

Completely independent thrusters used for cruise vs. for lift without any thrust vectoring.

Wingless MultiCopter

No thruster for cruise – only for lift

Hoverbikes

The general class of hover bikes or personal flying devices with the primary differentiation being that the pilot sits on a saddle or is standing, or something similar. All are multicopter-type wingless configurations

Electric Rotorcraft

An eVTOL aircraft that utilizes a helicopter frame

Each of the above categories are plotted relative to each other and the data of the individual category graphs are shown relative to the field of the overall data.

I have not listed all of the projects referenced from the  http://evtol.news website. Where the project was listed as defunct, was clearly an amatuer student project, was clearly very preliminary or had few useful details the project was omitted.

Our intent is to update the rankings on a semi-regular basis and projects come and go and projects refine their designs.

Results

For each category of UAV we have created a graph. This graph represents the certification and market risk. The further the trace is to the upper right hand corner the better the overall score, the closer to the bottom left hand corner the lower the overall score.

For each category we have listed the top 50% of the projects highest score first.

For the overall list of projects we have listed the top 30 and feature the top 5 in a little more detail.

The full spreadsheet of all the results is available on request.

The spread of scores for the 130 projects used for this study is as follows:

This spread of results shows a normal type distribution (bell curve), the mean score is 0.05 and the standard deviation is 0.26.

Vectored Thrust

Comment:

The vectored thrust projects occupy the range from the very low scoring to the very high scoring. This is due to the range of concepts on offer.

The better scoring concepts have limited mechanical complexity. 

Simplicity is good for certification and the market. Complexity is poor for certification and the market.

Top 50% Vectored Thrust Projects

Lift + Cruise

Comment

The lift and cruise category tend to moderate the range of design concepts on offer to ones that appear more conventional and this results in an overall better market score.

However the range of complexity on offer creates a wide spread of certification scores.

Top 50% Lift + Cruise Projects

Wingless MultiCopter

Comment

Wingless multicopters tend to have low mechanical complexity and this results in generally high certification scores.

However, the non conventional multirotor configuration makes these aircraft a difficult sell in a conservative marketplace

Top 50% Wingless Multicopter Projects

Hoverbikes

Comment

Hoverbikes are generally simple, and carrying only one person and having a lower gross weight makes them more suited to the certification process.

The low carrying capacity reduces the size of the market and the potential for making a profit on these projects is limited.

Top 50% Hoverbike Projects

Electric Rotorcraft

Comment

Some Electric rotorcraft have high market acceptability as they resemble traditional helicopters, the more exotic concepts

Top 50% Electric Rotorcraft Projects

Results Summary

Top 30 Overall Projects

Conclusion and Round-up

The top rated projects are as follows

1. TranscendAir

This placing of this project came as a surprise to me – but it is clear why they have placed at number one in the list. The aircraft has only two lift rotors and is largely similar to the V-22 configuration.

Certification abhors innovation and the familiarity of this design concept will serve it well with certification and the market.

2. Dufour aEro 2

Dufour is another twin lift propeller, tilt wing. It looks conventional but has VTOL capability. The tail mounted propeller gives additional motive power for horizontal flight.

Simple, almost conventional. Low risk

3. Flexcraft

Fixed wing with embedded lift fans and pusher propeller for level flight. This is a simple approach and looks conventional. Similar to the Ryan Vertifan this concept is relatively low risk and benefits in both the certification and market metrics.

4. DeLorean Aerospace

DeLorean combine a relatively conventional configuration (tailless canard) with great looks thanks to project lead Paul DeLorean. Two lift fans that also serve for level flight. 

In the interest of full disclosure, I am an advisor to the DeLorean project. They have been quiet recently but I expect we will hear about some progress in the near future.

5. Samad Aerospace Starling Jet

Samad Aerospace Starling Jet is a personal favorite of mine. I was privileged to be their acting CTO from 2018-2019.

An attractive classical design (reminiscent of the old Handley Page Victor – thanks to the multi-talented Norman Wijker) paired with relative simplicity makes this a high scoring configuration.

Conclusion

My experience, and the historical record, shows that simplicity and convention do well in the certification process and the market.

If we are about to see a paradigm shift the future could look quite different. Has the psychology of the regulator and the market shifted to the degree where success of these new types of aircraft is now possible? Or are we limited to moving forward in small, low risk increments?

Will the world’s emerging economies and societies with their ability to embrace change, be the environment where these certification and market innovations are possible?

Or will the FAA and EASA lead the way?

We have just hit 7000 downloads of our free Aircraft Structures Engineering Manual. You can download the third edition for yourself at this link

We have created a unique reference resource that is linked to every reference text cited and all methods shown link to hundreds of free analysis spreadsheets.

We host all of the reference materials and spreadsheets ourselves and we ensure that the links are permanent and persistent.

We are working on a fully online version of the book and hope to get that live on our website within a couple of months.

This essential reference manual is the centerpiece of our technical library which passed the benchmark of over one million downloads last month.

Thanks to all of our users and supporters – we could not do this without you.

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A version of this article first appeared in the June 2019 edition of our free newsletter, to subscribe click here

I have been thinking about what to do about the removal of data from the public domain and the unjustified de-validation of the remaining public domain data.

Part of the problem is that we are relying on older and disparate sources of information. As they get older the FAA are getting more nervous about them (even though the materials and fasteners are made to the same standards)

I have started a second book – a companion volume to Analysis and Design of Composite and Metallic Flight Vehicle Structures. 

It will be a compilation of all of the material and fastener allowables from every credible source. It will cover metallic materials, composite materials (Mil-Hndbk-17, AGATE and NCAMP data) and fasteners.
The hope is that collecting them in a referenceable volume it will retain accessibility and credibility. 

We will make the book available for free for everybody.

In the last month I have digitized all of the Mil-Hndbk-5H mechanical joint data (I was sleeping too much anyway), for each set of fastener strength data I created a graph.

The reason for this was to help me spot my errors in data entry. I always like fastener strength data presented like this – I find it much more intuitive.

I have not included the fastener limit strengths – would that be useful? Let me know by contacting us

In the process of doing this I found several obvious errors in the data.

In the book we issue, these will be highlighted and corrections suggested to keep to the shape of the curves consistent for the fastener in question.

My aim is to continue with this until I have all of the public domain data collected and presented in a more intuitive format than we currently have.

I intend to cover all standard hardware and include all of the useful data from the specifications so there is no need to go hunting for the specification sheet to figure out which grade of steel that particular washer is made from.

I already have about 300 pages completed with all standard public domain specification rivets and all Mil-Hndbk-5H fastener strengths.

Next – Metallic material strengths!

A version of this article first appeared in the June 2019 edition of our free newsletter, to subscribe click here

We have some new spreadsheets to release. We have been working with the Indian multinational  Dynamatic-Oldland Aerospace. Part of the work we have been doing is to develop some in house stress analysis methods for them.

We have developed two spreadsheets for them which are unique and Dynamatic-Oldland have graciously allowed us to release them on our website for free as a collaboration between Abbott Aerospace and Dynamatic-Oldland.

These two spreadsheets use the same method to develop load distributions for bolts in lap shear joints or bolted doublers.

The paper the method is based on (AFFDL-TR-67-184 Analytical Design Methods for Aircraft Structural Joints) is co-authored by W.F. McCoombs who also wrote the best parts of Bruhn and the supplement to Bruhn. The method has the same grace and simplicity as the rest of McCoombs work.

The spreadsheets use a little visual basic routine to force the re-run of the iterative solver each time any cell is changed. This means that these spreadsheets are more sensitive to changing and adapting them to your own format. This limitation is a small price to pay for the functionality they offer.

You can download them here:

AA-SM-290

AA-SM-291

Enjoy! (Courtesy of Dynamatic-Oldland Aerospace)

A version of this article first appeared in the May 2019 edition of our free newsletter, to subscribe click here

I was visiting a client and discussing the situation with the FAA’s management of the certification process, the regulations and the body of data that companies rely on to get through the certification process without reinventing the wheel.
 We agreed that over time there are more and more barriers appearing in the certification process.

It cannot be the case that these barriers are intentional and part of a larger strategy. It must be that they are incidental consequences to the general FAA strategy. A strategy that is meant to make certification easier.

Like all negative changes that drift into our society, they arrive very slowly in the guise of improvements or efficiencies.

Let’s go through the changes that have occurred since 2005. The reason for this will become clear.

The gradual erosion of public data.
You may have noticed that over time a number of critical data sets are being dragged behind paywalls. I have no objection to paying for good data but this is a little different.

We are being forced to pay for data that has mostly already been paid for by the public purse.

For example, the FAA will no longer accept a reference to Military Handbook 5 and you have to reference MMPDS – US$919 hard copy, US$719 Digital. The vast majority of the data in the MMPDS is unchanged from the data in Mil-Hndbk-5.

You have to pay for the MMPDS. Mil-handbk-5 is free.

Military Handbook 17 – the formerly public domain composites source reference is now rebranded as CMH-17, is owned by the SAE and costs US$872 for both the print and digital versions.

Many fastener standards which used to be in the public domain are now behind a paywall (SAE Fastener Standards, US$340, 2009 Incomplete). Testing standards, material standards, washers, sleeves, bushings, bearings. (ASTM Complete book of Standards US$13,168)

How long will it be before the FAA will no longer accept reference to a MS rivet spec and will only allow commercial NAS (AIA Individual standards between US$50 and US$70) or SAE standards (Over 2900 standards related to part 23 aircraft certification on the SAE web store, about US$80 each)?

To add insult the injury the great and the good have decided to slowly ‘sunset’ the MMPDS data.

I have written about this before. This means that after a period of time test data is assumed to ‘go bad’ and will no longer be available. A contact of mine has brought it to my attention that the honorable Battelle Memorial Institute will continue to include data only if you (not they) pay for the testing – and you have to pay them to carry out at least 25% of the testing.

So let’s get rid of public data that we have no reason to believe is erroneous (That nevertheless we have put behind a paywall to the benefit of a large private organization) and force you to pay the same organization to replace the data that it got for free (and you pay to use) so you can continue to pay them for data that you paid them to recreate.

The Battelle Memorial Institute may be a not-for-profit. However, it is run by cut-throat genius’s who have convinced the government and the industry to give them a license to print money. But it is definitely not for profit – just to be clear that no one is making a lot of money out of this.. Corporate net income is not profit as long as you invest it in the right things.

When you pair this with the new ‘consensus standards’ – you take the existing advisory materials and special conditions, developed with public money, and license them to another not-for-profit (note: the right kind of wealth is not profit). Remove the substantive data and details from the new regulations and reissue them as a functionally useless hollow shell.

Like the MMPDS data, it is not mandatory to use it, just like it is not mandatory to use the ‘consensus’ standards. It is just impossibly impractical and unfeasibly expensive not to use either.

So you have to pay your money and help these deserving not-for-profits see significant increases in their definitely not-profits. Presumably to fund their not-wages and not-bonus packages for their executives.

What is the outcome of these changes?

• We have unavoidable additional cost imposed on the aircraft developers
• We have legal jeopardy imposed on aircraft developers – how far does fair-use of these copyrighted materials go. Can you use excerpts of anything behind a paywall in your in-house reports? Can you distribute those reports outside your organization? Can you give presentations in public or private including that data?
• We have uncertainty in the part 23 certification process. Rather than an incremental change, we have quite a shift in philosophy away from ‘prescriptive’ regulatory requirements to, in many cases, more detailed and more prescriptive ‘standards’. But don’t worry, the standards are not mandatory, there is just no other way to certify your aircraft.

The abdication of responsibility for developing new standards and improving old standards

The new ‘consensus’ standards have a very unwelcome side effect.

As can be seen with the new draft regulations for Electric VTOL aircraft, the new structure for the regulations make it easier for the certifying authorities to cover new types of vehicles. Awesome. However the regulations avoid almost all specifics as the authorities now leave it up to the industry to develop consensus standards.

You won’t be getting those prescriptive standards from the regulator anymore. We just have to…….make them up? Wait for our vaunted industry bodies to come up with them and then pay to find out if they may or may not be useful?

The result of all of this slow grind of degrading a once functioning system is that it is more expensive and more difficult to certify existing type of aircraft and the government has shrugged off all responsibility for developing the details of the certification standards for new types of air vehicles.

In addition to this there is now a group of organizations that have been given the license to generate large amounts of non-profits.

The withdrawal of direct FAA involvement

The FAA is moving away from direct technical involvement and encouraging the use of Design Approval organizations.
This is causing a lack of direct technical experience and knowledge at the FAA as the organization moves out of the technical and into the purely administrative. So they are reducing the staff they recruit or retain with practical technical knowledge.

My experience and the experience of those who share their stories with me is that direct technical interactions with the FAA are becoming more protracted, antagonistic, time consuming and therefore more expensive.

To Summarize

On the face of it, the FAA is abdicating responsibility for updating existing standards, developing new standards and divorcing itself from direct technical involvement in aircraft development. You would think they must be able to save a lot of money – right?

(https://nataspolicyplaybook.wordpress.com/2015/02/05/the-faa-budget-request-for-fy2016/)

So we are paying the FAA more to do a whole lot less while they force the industry to pay for once public data.

There is something wrong with this picture. So what can we do about it? Some ideas on that next time.

A version of this article first appeared in the April 2019 edition of our free newsletter, to subscribe click here

This is the article I intended to write for last months newsletter, until I got side tracked by a Forbes magazine article. You can read that article here.

This article is about the personal conflict of interest that occurs within Design Approval Organizations. This a conflict that arises from the dual loyalties of technical and certification and the company commercial side. It also occurs for consulting delegates to a lesser extent.

Any conscientious engineer will feel this conflict at some point in their career but delegated individuals in the DAO are definitely at the pointy end of the stick.

The balance between the commercial and the theoretically perfect product is ever present in engineering development.
As you refine your product further (it does not matter if it is an aircraft or a toaster) each successive improvement costs incrementally more. We all know this as ‘diminishing returns’

This can be applied at any level of the development process to any aspect of the process. Producing a perfect drawing or stress report, creating the perfect quality system that is 100% fool-proof, writing the perfect maintenance manual.

The good engineer has to have an instinctive feel for cost, or when you have hit the magical point of ‘good enough’. This is not taught in college (or at least it was not when I went to college) and it is hard to teach as a general sense – because it depends on the product, how it will be used, the warranty you offer and what the legal and social expectations are.

No one expects a toaster to last for 40 years but people do expect an aircraft to remain in service for that amount of time. The point of ‘good enough’ is very different when comparing a vacuum cleaner or pocket calculator to a transport category aircraft.

The regulations are our most important guidance for ‘good enough’, the regulations, or more importantly the interpretation of the regulations, are a direct driver on cost. Because of diminishing returns and how far up that curve the aircraft development process already is, if the regulatory goalposts move just a little bit there can be a very large increase in cost.

So the pressure falls upon the delegated individual who makes a finding of compliance or recommends a finding of compliance to the regulatory authority. Their decision of when the standard has been met and therefore when they can make a finding of compliance can have a disproportionate effect on the overall cost of a program.

This presents a potential conflict of interest with their employer.

Having said that, the view from the other side, the side of the employer is sympathetic. The aircraft developer wants the best product possible and seeks actively to avoid failure of their product in service so there is a large convergence of interest with their delegated individuals.

When using consulting delegates I have seen aircraft companies engage in the practice of delegate shopping. They will start a program and select a delegate or group of delegates to assist in the compliance side. If cost becomes an issue part way through the program, working with a delegate who has an inflexible standard (or not flexible enough standard) for a finding of compliance can be expensive. There are options when it comes to consulting delegates, so companies can shop around to find a delegate who will make a finding of compliance at a lower standard and cost. I have seen this happen – it is not always bad. Delegates can be unreasonable at times. Some companies regard any delegates signature as good as any others and this can lead to ethically questionable methods to get a finding of compliance.

The abuse of consulting delegates can be problematic, but each delegate is an independent checker and reporter to the regulatory body and if a delegate has been replaced, and is concerned about any airworthiness aspects, they have a direct route to the regulatory body and can voice their concerns. This limits the abuse of the system.

The best approved design organizations therefore must have delegates with compete technical and commercial freedom that live outside the regular organizational structure.

We work on a semi regular basis with a well known part 23 OEM. Their internal design approach organization arrangement is, in my opinion, ideal. The ODA unit member has compete autonomy and no commercial responsibility. He is allowed to be diligent and at times he can even be reasonable……and as difficult as getting our work approved can be I have no concerns that compliance standards have not been met. I do not agree with all of his decisions and that is just fine.

So this brings us around to the Boeing 737 max problem. Boeing are an approved design organization and to me it is inconceivable, considering all of the checks and balances that should be in place, that this could happen.
From what I have read and heard from my contacts in the industry it appears the following has now been established

• The 737 max has software control in (at least) the pitch circuit of the flight control system.
• The purpose of this software is to make the aircraft behave like the previous versions of the 737 to minimize pilot conversion training.
• The level of criticality of this system was incorrectly classified at a lower criticality than was correct.
• The incorrect classification of the final system design was due to the system being modified part way through development to give it greater authority than was originally envisioned.
• The pilot training on the specifics of how they system operates was not adequate

If this is correct there are two specific failings:

1. The impact of the change to the system was not assessed correctly and in the conduct of all subsequent qualification and compliance activities this change in criticality was not acknowledged or addressed
2. The authority of the system as designed and the effect on the extent of pilot training was likewise not addressed at every stage between the design change the implementation of the training program.

If this is the case and this was a small company where maybe one or two truly qualified and experienced engineers would be responsible, this outcome may be conceivable, even probable. 

If a company the size of Boeing where many, many engineers would be involved it is almost impossible to conceive that multiple flags would not be raised during the development process.

How many engineers with quiet reservation signed off on design documents, system safety assessments, test plans, test reports, compliance reports? How many technical managers who could clearly see the impact of the system at the aircraft level bit their lips in meetings or deleted an email calling the approach into doubt before it could be sent?

All engineers know the pressure. The group dynamic is at times, irresistible. The ability to compromise your ethics is not black and white. There are more than 50 shades of grey. Morals are binary – there is good and bad. Ethics are a balance between what we know to be moral and the real-politik of commercial reality.

Ethics are the internal rules on a sliding scale between perfection and the compromises you make to continue and advance your career.

A good project manager I used to work with told me the following:

“It is ethical if you come out of a meeting and you are comfortable that everything you just discussed can appear on the front page of tomorrow’s newspaper”

What do you do when the project group you work within starts to drift off track? At what level of ethical discomfort do you speak up? Do you speak up at all? Do you stay? Do you leave?

I don’t know what the development environment was like for this project at Boeing but something happened. A group of professional, competent people delivered something that was flawed. We can all think that it could not happen if we were on the project, but given the right conditions, even the most diligent people can fall prey to a sophisticated ‘go along to get along’ mentality.

So keep your standards high and if the worst comes to worst sometimes you just have to walk away.