9 Jun 2009
An Impossible Dream
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‘An Impossible Dream’ – will be published later this year. Draft text of the book is here presented for comment. Copyright applies.
o
About all composite aircrafts.
‘An Impossible Dream’ presents an in depth review of the application of plastic composites in aircraft, in particular all-composite aircraft presently developed by Boeing – 787 Dreamliner – and by Airbus – A350 XWB. Composites do not provide the expected weight savings and the safety of all-composite aircraft can be seriously questioned. These aircraft will never attain the safety standards set by aluminum aircraft – not even near. It is therefore difficult to understand why Boeing and Airbus engage themselves with such projects. The book presents a detailed review of the development of these aircraft, reflects on history and discusses the pros and cons of composites in some detail – an alternative approach is put forward.
Introduction
1. Aiming for complete control of the market
About an entertaining relationship
2. Lessons from history
About ignorance
3. Front runner
About Dreamliner 787
4. In comfortable second position
About A350
5. Pro and con and so on
About composites
6. Not suitable
About damage tolerance
7. All things considered
About aluminium reinforced composites
All composite anatomy
References
Appendix – Comet accident
Appendix – Concorde accident
Appendix – Columbia accident
and designed by 
I got the link to your site via TUDelft. A very thorough overview on the current developments at A&B, some solutions can be so simple… Though knowing the organisation and balance of powers at Airbus (you will have read some pages on the acceptance of FML within Airbus in the book from Ad Vlot), your back-up solution for A350 might not be as straight-forward within Airbus. Your contacts at TUD might be able to give a better insight on this part of the story
Groeten uit Hamburg
Frederik
June 15th, 2009 at 23:42permalink
Dear Hans,
All sincere congratulations upon your draft book, very timely and well done. I am a Composites engineer and agree with most of your thoughts and comments and have been in touch with FAA often re FST hazards on 787 and would your consent to prepare some comments for your draft book. I presume that you were or are involved with GLARE in the Netherlands and I have had a series of technical debates on technical matters such as potential CTE issues with engineers re GLARE.
All congratulations again
With Best Regards,
Derek
Derek
June 23rd, 2009 at 21:12permalink
Sir!
Your statement: “the safety of all-composite aircraft can be seriously questioned…” can be seriously questioned.
As long as you can demonstrate compliance with all requirements, an all-composite aircraft is as safe as made out of any other material, if it has been designed to meet the same requirements. I don’t believe that the AA will certify an aircraft not meeting the rules.
About Airbus design there are four teams in four different nations, France, Germany, Spain and UK.
About A380 The complete rear end is composites. From the pressure bulkhead to the end, not only most of the vertical tail; but the full horizontal tail plus the last 9+7 meters of fuselage.
You can check your sources.
Regards, Luis M. Fernandez
Anonymous
June 25th, 2009 at 23:56permalink
I’m not qualified to comment on the engineering aspects, but I think some other sections could be improved:
“The target weight had been exceeded by some 5,500 kg (~12,000 lbs) – the equivalent of 55 passengers – regardless enormous effort, but the composed structure was a success and still saves considerable weight – it would have been impossible to fly the A380 without composites”
Comparing the weight to equivalent passengers is useless. Extra weight primarily causes problems for cargo and range. Especially if the MTOW is raised, range will be the only problem. It is also worth mentioning that in this case Airbus delivered on fuel burn *despite* being overweight, even if your point is about composites – not every aspect needs to succeed at exactly 100%.
This should be kept in mind for future models as well: despite being above target weight on the XWB, Airbus already reduced engine thrust requirements once, and then raised them to be either the same or still lower depending on model. This means that low speed aerodynamics are overperforming. The same may apply to the 787, especially if some of that extra weight has been put into a more aerodynamically efficient structure.
I would compare weights in %. 5500 kg means nothing to me given the size of the aircraft, and the other aircraft aren’t even the same size as each other, let alone the A380.
The wiring problem is indeed interesting, but your title should make it clear that the problem wasn’t with the aircraft itself, let alone composites (”A380 – a giant airplane causing giant problems” – MISLEADING given your book’s topic).
Your description of the other problems borders on scandal seeking: “However, soon the A380 disappointed the world at large. In a shock announcement Singapore Airlines warned that when you have the privilege to share one of the private cabins in front of the plane provided with airborne double bed with your secretary, inappropriate activity is not allowed for.”
Disappointed the world at large? Really? Because one airline says you’re not allowed to have sex in its luxurious beds? Come on. Not only is being too silent a simple “problem” that can be remedied in future models, but everyone will just get around it by having sex quietly. Turn this paragraph into an (more?) obvious joke and it’ll be good.
The shower incident is more interesting, but it was Emirates who were stupid enough to want showers. Even if Airbus custom designed the system itself and failed, that’s still unrelated to the success of the A380 program or composites. Besides, how does this support the point you’re making? The cabin section was flooded of all things, but the aircraft still landed safely and needed relatively little maintenance based on the downtime. Seems to me that’s a good thing!
(Had the aircraft crashed due to the nude muslim woman hindering male help, by the way, that would be an excellent Darwin award candidate
.
Your comment about AA587 is downright stupid: “The structure fulfilled its duty because the vertical tail has been loaded above ultimate, i.e. outside the certified load envelope, but it might be speculated how a structure out of aluminium reinforced composite would have behaved.” Quite obviously imho, a different material would have had a different weight, but still be designed to 150% in order to minimize it and also failed. If you have more insight into this than I do, explain what you mean.
The A300 doesn’t have flight envelope protection anyway, making this argument pointless.
Anon
June 26th, 2009 at 12:50permalink
Dear Hans,
as an independent thinker, you should always question everytingh and this is what I do. However, I’m sure you will agree with me that, certification rules can be seen as a consequence of accident analysis. Today, they are a big collection of the different limits encountered along the comercial aviation history.
The independent thinker will ask; have we encountered all the limits? Obvious answer; no, or, we don’t know. So Certification is not a waranty of 100% safety.
Once said that I have a look to your parragraph on “Certification – although…” and desagree with the use of “often”. If I look at statistics, structural failure is not the more frequent cause of them, and within them due to new material or design flaws are much less than due to bad maintenance/repair practices. Also getting out of the normal flight enveloppe, extrange piloting practices take part of it. To give you two especific examples. One case of a failure of a flap-track in fatigue at less than 1/20 of the expected life. The finding was a few pilots maintaining cruise level more than per plan. Then diving for a quick descent, selecting full flap, letting the “q” limiter to self retract if max placard speed was exceded. Consequence the number of flap cycles per flight went from one to more than 30. Thanks god, no accident that time. Second case, use of a long range, high capacity aircraft in short routes between big, overcrowded cities. Intencional increase in the diferential pressure to improve? the confort to the “compressed” passangers. Consequence failure in the pressure bulkhead, loss of the aircraft and loss of lives.
With respect to the 150% Limit Load used for analysis and test of composite structures. There is a big in service experience to support. A310 VTP full composites started service flights don’t remember the exact date; but was latest 70s or early 80s (Initial design was metallic, changed to composites at that date). A320 VTP and HTP both full composites, started to fly in 1987.
For lightning protection. Inside those HTPs and VTPs there are very limited electronic equipment, shielded with a few grams of Al foil and/or copper mesh; but there is some and without any known lightning problem (I assume that with the statistics of the number of lightnings hitting aircraft per day they must have received hundreds).
Increasing complexity all HTPs of A330, A340, A380 serve as fuel tanks, like wings. They are protected with a few Kilos of bronce mesh. Again no known problems (in all cases local burned spots without tank penetration).
I don’t know if this gives you any feeling about faraday cage; but gives me some confidence that it might work. What do you think about cars being a faraday cage with the big windows not being metallic?
Crashworthines, I dont have the slightest idea of the behaviour of a complete fuselage. All I’ve seen is impact test with steel, aluminium, carbon, glass and kevlar rods. Here, depending on the design, the more efficient in energy absorbed per kilo of structure was the carbon rod. Of course, different design will yield different results.
I don’t know the specifics about the A380 wing test failure; however I can tell you that the load in a wing in real flight come from a continuous air pressure and load distribution; whilst in a test is a stepped distribution of load. As a consequence when designing a test set-up, any responsable test engineer will ensure the local test load to be above the corresponding air load. So if AA approved that test without repetition, I can imagine they have checked that the load at the failure section was on the safe side.
Jumping into the application of a totally new material, without in service experience is the foolish thing an engineer can do. Today I don’t believe this is the case with composites. Besides those experiences I’ve mentioned above, there are other components like 10 sets of upper VTPs that were flying in DC10s for about 10 years, plus additional components flying in other types and subject to frequent inspections to gain experience, not to mention all military aircraft.
In conclusion I see more the danger comming from a lot of small details than a change in material, when the design is done properly. Design flaws can always ocurr; but full scale tests are there to catch them. I’ll be totally affraid the day the so called “virtual testing” is accepted as compliance means (if ever).
I must admit that still haven’t read the complete draft of your book. Once I’ve finished, I’ll come back to you if I have any comment.
Hope this long mail makes any sense to you, regards,
Luis
Luis
June 27th, 2009 at 01:18permalink
Happy to see you speak out about issues with plastic airplanes.
Here is what I wrote on the 787 in July 2006:
http://www.boeing787skeptic.blogspot.com/
And 5 or 6 years before that, Aluminum vs. Composites:
http://www.aerotalk.com/index.cfm?action=view&ForumID=8
Keep up the good work.
Stan
Stan
June 27th, 2009 at 15:54permalink
Hans,
I recently ran across your prerelease on composite aircraft and believe you have gone out there a bit to the extreme. Composites can be superior, it just takes far more finesse, competence, and design skill to make them work. And hence the biggest reason for the failure of composite designs to be competitive is the lack of talent doing the designs. In case you are not aware, most of the aircraft industry has gone to an integrated project team type organization where engineers are just a widget in a plug and play system, with any one of them being basically considered of the same caliber as the next. Likewise with subcontractor input and parts. What this leads to is management having no clue as to how good the performance is and where or who has any expertise to excel and get the best results. The answer of one engineer is just as good as another. One subcontractor is just as good as the next. Under this type of organization the design gets mired in mediocre output just when the use of composites demands excellence.
I am a very experience structure analyst that has worked on many composite aircraft, everything from the B2 to the most recent being the Global Hawk. The use of all composites for the Global Hawk wing for instance gives results that one could never achieve with metals. It uses high modulus fibers that provide the stiffness the wing needs to make the wing very long in span to maximize its lift potential at a much lower weight than can be achieved with metals. And most of the wing is just glued together to minimize the costs of its assembly. This is just one example of many.
My point is that from what I have read, you are making statements in your book that are a little too pointed or extreme and you may want to consider toning them down or better define them instead of generalizing to the degree you seem to be doing. The key to success with composites as with all things is judicious use of them by skilled engineers — not widgets doing the work.
Admittedly, I have not read all of your book, but will if I get time. From what I have skimmed however, this is my response.
Good Luck, I know how much work doing something like this is.
…Bryan
Bryan
June 27th, 2009 at 20:33permalink
Hans,
A review of your book has been posted on Plane Talking.
http://blogs.crikey.com.au/planetalking/2009/06/28/dreamliner-an-impossible-dream/
I think it has made an important contribution to public discussion about future issues that may arise with high composite airliners.
However I think you should disclose any involvement with any of the interested parties in this issue, should this be the case, in the interests of full transparency.
We need to know more about you.
Ben Sandilands
June 28th, 2009 at 04:12permalink
The dream IS possible.
The problem with Boeing’s Dreamliner is relatively transparent,
Boeing simply wanted too much at once:
- New logistics (production scattered all over the world,
assembly in Everett),
- New technology without previous know-how and experience
(composites, mixed composite-metal constructions and their
bonds and so on),
- New maintenance scheme (an aircraft which measured and
self diagnosed by its board computers all the time, finding all
the possible problems before they lead to failure).
All this can be resolved, but it requires very much time and it
signifies a steep learning curve on the development as well as
on the production side.
The impending failure of Boeing’s Dreamliner has the following reasons: Boeing wanted to catch up with Airbus in one single giant leap forward. But Boeing underestimated the difficulties involved. Boeing had nearly no foreknowledge about distributed production, about composites, composite-metall constructions and their bonds and also about self diagnosing
engines.
This is, why Airbus will succeed with the A350 XWB. Because
Airbus already has all the foreknowledge required. Airbus
already uses all the logistics and technologies involved to a
lesser degree in its existing products, especially in the A380.
Airbus has a solid fundament of knowledge and experience in
these fields, on top of which it can build up.
There is much more time available for the difficult finesses,
for ingenuity based on time consuming experiments.
To get the required results during development of a new
product, a certain serenity and sobriety is needed.
All this is not possible, if you must start everything from
scratch, if you are in a constant hurry, always teetering
on the brink of overchallenge.
Evin Ormond
June 28th, 2009 at 12:09permalink
Hans,
I have been a structural engineer for over 30 years and have been exposed to many different types of composite structures.
Stated simply, I cannot understand the almost religious obsession with the aircraft industry and composite materials. I have witnessed numerous failed structures as well as programs due to this obsession.
I will not bore you with details now. I just wanted to touch base with you since I just learned of your website Lonely Scientist. I am looking forward to studying you work and would like to follow you in your journey.
I too would someday like to write a book on this topic… who knows, maybe I will.
Should you ever send out information to followers via email, please include me on your list.
Sincerely,
Martin
Martin
July 2nd, 2009 at 13:56permalink
Hello Hans,
No comment or so, but only some language problems. Do with them what you like.
chapter 3
Other special conditions
Recent research by the FAA shows that aluminium fuel tanks behave indeed very differently from aluminium fuel tanks 245).
I think first word aluminium has to be composite:
What’s left is improved flying experience
is applied – horizontal gust horizontal gust suppression is already applied with the 777 and the 787 is also
I think horizontal gust is double
Take Care
Moreover, the 787 is a fist ‘more electrical plane’ and that might play havoc
fist???
With kind regards,
Anonymous
July 5th, 2009 at 01:30permalink
Your comment about Airbus ‘initial success coming from its engineering is interesting. There is an interesting lesson in F1 at the moment – with the significant rule changes it seems that the teams with the best technical directors have been the most successful at implementing the changes, whereas when the rules were being modified slightly, budget played a bigger part because it was about having the money to be able to perform endless iterations.
Airbus started from scratch (albeit with significant experience in the founding UK, French and German companies) and so had a freshness to its design that Boeing didn’t have. Now both companies have significant expertise in metallic aircraft design, but they are at a ‘rule change’ that makes the F1 rule change pale into insignificance. This rule change from metallic to composite primary structure in the aerospace industry calls for brilliant engineering solutions, not iterations of a structural design philosophy that has hardly changed since the Boeing 707. It seems to me that both Boeing and Airbus are producing ‘black metal’ versions of metallic aircraft, because they have spent so long iterating the metallic designs that they have forgotten the first principles, and evolved their current design rather than taking a fresh look at things. Certainly if you were to look at a digital mock up of an A350 wingbox and an A330 wingbox you would be hard pressed to see any significant differences. So, money is being poured down the drain because both the industrial behemoths are relying on their previous experience to build a metallic aircraft made out of composites, rather than recruiting Burt Rutan style engineering brilliance to design a truly composite aircraft. Like the big F1 teams they will get there eventually, but they probably won’t get produce a truly successful composite aircraft until the next generation of single aisle aircraft, which from what I have seen appear much more innovative. That is if they don’t have their fingers burnt too badly on their 787/A350 programs….
Finally, you mention the engineering expertise in Germany and France behind Airbus’ intiial success. You should note that the wings are designed and built in the UK and are extremely aerodynamically efficient and weight efficient compared to the Boeing wings. The wings are the most technically challenging structure on the aircraft, and therefore I would argue that, in terms of the structure, the UK has produced the most innovative and successful structural items for Airbus.
I’ll get on and read the rest now. Having worked on Airbus A400M and now A350 since 2002 it initially looks like you are talking a lot of sense, but I’ll reserve final judgment until I have finished!
Andy
July 10th, 2009 at 22:42permalink
Dear Luis,
Thank you for your comment. Of course my statements must be questioened, that’s why I took the unusual step to publish the draft text on the web for comment.
More specific to your comments. I am not sure whether it is important at all whether you believe or not believe AA certification. As I state in my book ‘Certification – although recognized to be of utmost importance – is in this respect a relative idea since every commercial aircraft that crashed in the past was certified and flaws in design and unknowns including wrong choice of construction materials or different then expected material behaviour were often found afterwards to be the cause of accidents including a number of fatal accidents – some described in detail in appendices of this book’. It is also not relevant that four different nations are involved and that applies also for the application of composites with an aircraft that is just in the air.
My request is therefore to more specific. For example how do you know that the 150% safety margin applied with testing of aluminium aircraft does also apply with all composite structures – engineers that designed the Comet deemed 200% enough, four planes crashed and hundreds died because of ignorance. What do we know about crashworthiness of the 787 other than some verbal ‘assurances’ from Boeing and that applies also – even more so – to lightning strike protection. Do you really belive that a couple of hundred of pounds of copper wire mesh in the composite provides a Faraday cage – prove it. And what about electromagnetic shielding with hardly any metal left. My book discusses many of such issues and again – come with specifics.
Having said that I believe that the A380 is a great plane that paves the way for composed aircraft. However, safety has to be awaited. Personally I don’t feel comfortable with the wing test that broke some 3% short. The rules of the game – as I understand them – are that when you strengthen the part, the test has to be repeated. Be very careful with CATIA when composites are involved.
I would very much appreciate to receive more specific comments – hope that you do.
Regards,
Hans
Hans van der Zanden
July 10th, 2009 at 23:19permalink