Mr John Leahy Speaks Out About Airbus.

coa747 · Thu Nov 16, 2006 1:04 pm

What would you expect him to say. He and the rest of the bunch at Airbus blew it big time. They sat on their butts and hoped Boeing couldn't pull it off and when the orders started coming in they back pedaled. Then tried to scare everyone with claims of the dangers of carbon fiber. Instead of focusing on their own product line they bashed Boeing. Now they are really in a mess. The XWB still hasn't been launched even though we hear rumors every day of its impending launch. Now after bashing carbon fiber they are speaking its praises. That is a lot of crow to eat, and I can't help but be amused. Airbus has lost its inovative edge and isn't likely to get it back anytime soon.

2wingtips · Thu Nov 16, 2006 1:13 pm

Quoting NYC777 (Reply 107):
Quoting NYC777 (Reply 85):
Look again, I did source it:

Quoting NYC777 (Reply 16):
All those comments are archived on another site (www.fleetbuzz.com, in case you're interested).

Quoting 2wingtips (Reply 102):
You telling me you compiled these on your own and didn't just copy them from Orders/Fleetbuzz?

You needed to source who compiled the list, not the sources for each individual clip.

I never said such a thing. I told you (again) that I got it from Fleetbuzz. Don't start making false accusations against me.

Absolute rubbish. In the original post there was no reference to where you sourced the material. That is where it should have been and that is clearly appropriate. You did not do that. I still can't find the mention of the fleetbuzz reference. Fleetbuzz had permission from the original compiler which at no stage has been mentioned by you.
These are not false accusations,sir. You are very lucky the moderators haven't wiped your post, which I think they should have.

ikramerica · Thu Nov 16, 2006 3:08 pm

Quoting AirFrnt (Reply 74):
Even when Boeing basically had the 757/767 market to itself, it's timing problems kept the plane from being the same runaway success as the 707, 727, 737 or 747.

2000 jets for the 757/767 program. What a failure...

Quoting TeamAmerica (Reply 99):
Use the SUGGEST DELETION button. The mod's are pretty good at cleaning up nonsense like Chiad's post.

You'd think so, but they've ignored this request a few times when it involves an anti-American statement such as this. Including this, as I suggested deletion yesterday.

Now, say anything whatsoever about Arab policies in the middle east, and you'll get your post deleted lickety split...

iwok · Thu Nov 16, 2006 6:10 pm

Quoting NYC777 (Reply 11):
"If the question is: if [Boeing] bring out the 7E7 what are we going to do? The answer is nothing. We are very content to stay with our A330-200." -- Reuters, 17-Dec-03.

Quoting NYC777 (Reply 11):
'[Leahy] said Airbus isn't planning any moves or product changes to compete with the 7E7. "We don't feel that we need to do anything with the product right now." -- Dow Jones Newswires, 24-Mar-04.

Quoting NYC777 (Reply 11):
"We have been listening to the airlines and going through the design loops. Our customers said we should have done this a year ago. But that's water over the dam." -- Seattle Post-Intelligencer, 3-Jun-05.

Absolutely priceless! How come he wasn't ejected with his old crony old noel? Such arrogance, which ceded a good size of the market should have been punished. bomb

I am real curious to see what the 350-XWB-Rev2 finally looks like. I am sure UH will chime in with his "comments"

iwok

autothrust · Thu Nov 16, 2006 7:55 pm

Quoting Scorpio (Reply 5):
Or do you (as I suspect) just slam Airbus out of habit?

Sure what else, thats what A.net is for. banghead

Quoting WINGS (Reply 10):
First of all I would like to express my disappointment in the way this thread has been turned up side down. While many have contributed in a respectful and informative and polite manner, others have done opposite.

Regards,
Wings

I would recommend to not post anything about Airbus in future, all the Airbus haters and bashers will be forced to search a new hobby. Sad

However i'm thankfully for your great and very informative Topic.(as always from you)

Funny how many people are upset with a guy wich only sells planes. Maybe sometime he will make a ludicrous Blog like Randy so you all can express your meanings about his person.

Quoting Columba (Reply 68):
Regarding this thread it is really weird how many people are bashing Leahy on everything he says but believe everything Randy Basler is writting in his blog.

Indeed.

Quoting Ap305 (Reply 24):
Hilarious to see people getting emotional and combative over a aircraft company and its chief salesman.

How true. But i would call this sick obssesion. crazy

Quoting Maperrin (Reply 82):
Don't you uderstand that your obsession against AIRBUS is poluting these forums ? An destroying the insterest we have for this website ? You urgently need a Shrink, guy !

I agree but he is not the only one.

Quoting Laddb (Reply 60):
I read the posts from some Americans and it makes me ashamed. I ask that you don't judge all Americans based on the few bad ones. Some of us respect our foreign friends and realize that all Americans' can trace their ancestors to some other country. Also, we are more similar than different, and that there is "arrogance and pride" in all nations. Just look how soccer (sorry - football) fans from the same country can beat each other up - verbally and physically. Some Americans treat Boeing as our home team and Airbus as the Visitors in this game of aircraft manufacturing. We can and should have heated debates over fact, but leave the mud slinging to the politicians.

Couldnt agree more and congratulate you for your fanatastic and balanced post. Welcome on my RU list. thumbsup

For me Boeing and Airbus are great Manufacturers but what i love from them are the planes and not the hyperbole from both sides.

As Aviation Enthusiast im not so pleased with the idea of Airbus plastic panels and think Boeing is technology leading in a impressive way. However its good they are forcing the A350XBW program and maybe they can gain new experiences for future aircraft with more composites. Both planes 787/350 look fantastic and i cant wait to see them fly.

F4N · Thu Nov 16, 2006 7:56 pm

To all:

An interesting post. However, I find the attempts by some members of this board to sanctify Leahy and absolve him of any blame for Airbus' current difficulties is absurd. The guy was the # 3 or 4 man on the food chain at Airbus for the last decade and as such, had to be fully cognizant of everything that was going on.
In addition, both Leahy and Forgeard were the ones who unhesitatingly and unstintingly took Airbus down the "7E7 ain't shit" road. While our friend NYC777 may have gone a bit far, his compilation of Leahy quotes sort of gives rise to that conclusion and it is difficult to suggest that Leahy's influence was not key to the assumptions Airbus was apparantly making.

I am not taking anything away from the guy's abilities or accomplishments. However, I think he was just as culpable as anyone in Airbus management and should have gotten the gate with his peers.

F4N

RichardPrice · Thu Nov 16, 2006 8:03 pm

Quoting Iwok (Reply 108):
Absolutely priceless! How come he wasn't ejected with his old crony old noel? Such arrogance, which ceded a good size of the market should have been punished.

You think Leahy was the one that took the decision on that? Think again - theres almost certainly a good reason why everyone else has been replaced and he hasnt.

bringiton · Thu Nov 16, 2006 8:15 pm

Given the last few years of Airbus sales and deliveries Leahy would be the last man that would be fired!! He has sold those aircrafts very well and it has more then compensated for some of the illadvised comments that he has made.

eisman · Thu Nov 16, 2006 9:26 pm

Two questions/thoughts:
1. Does Airbus need to increase A320 production rates to increase cash-flow?
2. Is composite panel "black aluminum" construction neccessary to appease labour unions and/or Airbus's financial government backers?

My apologies if this has already been discussed as I'm still working my way thru all the posts.

micstatic · Thu Nov 16, 2006 10:13 pm

Quoting Halls120 (Reply 17):
You have to understand that in the US, being a sales person isn't exactly a respected occupation, no matter what you are hawking.

That's funny. Didn't realize lawyers were up there either?

dl021 · Thu Nov 16, 2006 10:34 pm

Quoting Slz396 (Reply 4):
Although I've not often seen it explicitly, it almost always sounds as if many here would easily label him as and 'unpatriotic traitor', simply because he's working for Airbus!

Nah...the problem is that he spent too much time trashtalking his competition with unsubstantiated and unprovable (and eventually proven untrue) statements. The fact that he's American doesn't come into play. You'll notice that Boeing has spent much less time talking trash about Airbus, while Leahy and Foergard were spending more time speaking very ill of Boeing while ignoring their own mounting problems.

Quoting Slz396 (Reply 4):
hope he'll recover soon from his hart surgery not only for airbus, but also for his family.

absolutely.....no ill wished on anyone's health. He's been very successful and should consider his health prior to anything else from this point onward....there's no point to becoming rich if you don't live to enjoy it.

Quoting Scorpio (Reply 5):
When he admits to having been wrong, and changes his tone completely (pretty much exactly to what people here on a.net said he should change it to) you... SLAM HIM AGAIN and say he's

Quoting NYC777 (Reply 1):
desperately trying to pull his chestnuts out of the fire

Well, that's not really a slam. He is trying to pull his chestnuts out of the fire as they've fallen off the grill and are burning.......He admits it and is back to pushing his own product. I fail to see why some of the Airbus fans out there (who remind me of SEC football fans...'my two favorite teams are Florida and whoever's playing FSU') won't accept that the hyperbole and exaggeration from Airbus hurt them, or that they must change to survive (unless their governments are willing to prop them up) since they only have a slight lead on narrowbodies and are way behind on widebodies. Boeing recognized their deficiencies and instead of ignoring them they went to work and bet the company again on a huge step forward.....

Criticism...when leveled fairly and constructively...is not about making fun or denigrating for the sake of denigrating...it's about showing the way forward and exposing the mistakes of the past so as to avoid the Descartes syndrome.

The airline industry needs at least two healthy manufacturors in order to ensure that prices stay competitive and progress is assured......if it wasn't for competition we'd still be flying dirigibles and double deckers....

TeamAmerica · Thu Nov 16, 2006 11:51 pm

Quoting AutoThrust (Reply 109):
Maybe sometime he will make a ludicrous Blog like Randy so you all can express your meanings about his person.

Ludicrous? I find Randy's blog quite interesting at times. I very much wish Leahy would post a blog. We might get his comments in a more thoughtful manner, with proper context. As it is, he seems to be the lone arrogant American who gets a pass from my European friends. Why is that? Yeah sure

osiris30 · Fri Nov 17, 2006 12:07 am

Quoting AutoThrust (Reply 109):
Maybe sometime he will make a ludicrous Blog like Randy so you all can express your meanings about his person.

That's just an assinine statement. Randy's blog is at least an interesting read. I would rather read it from the 'horse's mouth' than from a likely to misquote reporter.

justloveplanes · Fri Nov 17, 2006 12:08 am

Quoting Katekebo (Reply 7):
From engineering point of view, making a fuselage with composite panels attached to a conventional frame makes little sense. The beauty of composites is that you can build complex geometrical shapes that are fully integrated from the structural point of view, allowinig the designer to achieve greater strength in the desired directions with less material (weight). Using composite panels with bring little (if any) weight savings, but Airbus may be forced to do it to bring the same level of cabin humidity as Boeing.

I agree about the cabin humidity, they have to do this, but gettting it as strong as a single piece is going to be tricky. Obviously, its probably going to be heavier, both on the panels and the frame.

One quick thought, if they make INTERLOCKING panels that are symmetrical (would drive a perfectly round fuselange), like those in a furniture dovetail wood joints, they could lighten things up by passing some of the stress from panel to panel and not just the aluminum. Symmetrical panels would support economy of scale. They would also have a lightning ground path so they may need less metal mesh in the panels as Boeing.

It sounds like the design has a lot of potential, except I'm sure Boeing looked at it and went the one piece way. Surprised that B got blind sided by the lightning strikes, would have thought they knew about that from the B-2.

I'd like to hear Randy Baesler talk about the 787 repair techniques. Those are probably under a secrecy agreement until the last possible minute. The Boeing fuselage might be so tough that repairs from ramp rash will essentially be cosmetic.

khobar · Fri Nov 17, 2006 12:25 am

Quoting 2wingtips (Reply 74):
He poached them from "orders" and then from "Fleetbuzz" and did not source either. He did none of this himself. Very disappointing performance IMO.

Quoting Maperrin (Reply 82):
Don't you uderstand that your obsession against AIRBUS is poluting these forums ? An destroying the insterest we have for this website ? You urgently need a Shrink, guy !

Quoting 2wingtips (Reply 95):
You telling me you compiled these on your own and didn't just copy them from Orders/Fleetbuzz?

You needed to source who compiled the list, not the sources for each individual clip.

Quoting PanAm_DC10 (Reply 101):
He's way out of line, no tick for him sir.

Quoting 2wingtips (Reply 106):
Absolute rubbish. In the original post there was no reference to where you sourced the material. That is where it should have been and that is clearly appropriate. You did not do that. I still can't find the mention of the fleetbuzz reference.

Did Leahy make those statements, YES or NO? If the answer is YES, then the source is Leahy, as NYC777 stated, no further sourcing is necessary, and NYC777 is owed an apology. If the answer is NO, then NYC777 owes us an apology. It's as simple as that.

osiris30 · Fri Nov 17, 2006 3:27 am

Quoting Justloveplanes (Reply 119):
The Boeing fuselage might be so tough that repairs from ramp rash will essentially be cosmetic.

It's either shattered or fine (structurally). The former is much harder than vs. AL.

Areopagus · Fri Nov 17, 2006 5:20 am

Quoting Osiris30 (Reply 121):
It's either shattered or fine (structurally).

I have seen fiberglass gouged or cracked without being either shattered or fine. Why is CFRP different?

Curmudgeon · Fri Nov 17, 2006 6:00 am

Quoting Areopagus (Reply 122):
have seen fiberglass gouged or cracked without being either shattered or fine. Why is CFRP different?

I think Osiris is saying that either its shattered, and requiring a section repair, or its only cosmetic, and requiring the equivalent of a tape job*

*tape is currently used to cover areas of slight damage in aluminium skins.

CFRP is much stiffer than fiberglass, and there is little extra bulk from resin that non-aerospace fiberglass has. Cracking isn't common, and the stiffness tends to distribute impact loads over a wider area, thereby resisting damage.
It is a little brittle though, so some rovings incorporate Kevlar yarn to improve puncture resistance. I don't know if the "CFRP" being used in the 787 is purely carbon or incorporates other fibres.

2wingtips · Fri Nov 17, 2006 6:13 am

Quoting Khobar (Reply 120):
Did Leahy make those statements, YES or NO? If the answer is YES, then the source is Leahy, as NYC777 stated, no further sourcing is necessary, and NYC777 is owed an apology. If the answer is NO, then NYC777 owes us an apology. It's as simple as that.

Rubbish again. The list of Leahy quotes was first put on the "orders" forum some time ago, then it was put on "fleetbuzz" with permission. To post it here with no referencing is wrong. It's an open and shut case. The acknowledgement should have come prior to the quoted list. To later acknowledge it from "fleetbuzz" is also wrong and the original posting on "orders" should have been the referenced source.

astuteman · Fri Nov 17, 2006 6:31 am

Quoting Baroque (Reply 117):
I remember Astuteman commenting how getting rid of overlaps could reduce weight on a welded Al-Li fuse. So how will the plates be joined?

With welded metal skin, there are two areas of saving over a "fastened" structure.

The first is the aforementioned "overlaps".

The second comes from the fact that, where the metal is perforated, it is by definition weaker than the parent plate. Hence it has to be thicker than if it wasn't perforated........hence the entire plate has to be thicker, as the plate will invariably be uniform thickness.

A "fastened" CFRP structure would to my understanding still need "overlaps" of some sort, but you WOULD be able to tailor the thicknesses of the panels so that you only had the re-inforcing thickness where you needed it.

From memory, back in the summer, FI ran a "special" on the Spanish Aerospace industry, and we followed that with a fair debate on how the tail-cone of the A380 (produced in Spain) was manufactured. (I seem to recall eating humble pie too blush

, but I digress Smile

).

From memory, the CFRP tail-cone on the A380 is essentially automatically laid-up CFRP panels rivetted or bonded to an Aluminium sub-structure.
There were some comments in the article that the spanish proved the business case for adopting this methodology for the tail-cone through the weight saved over a "conventional" Al construction.

How that compares to a) the original intent for the A350XWB (i.e. welded Al-Li - we assume) and b) what's actually intended for the A350XWB now (as opposed to a few tidbits dropped by JL), I don't know.

Regards

flysherwood · Fri Nov 17, 2006 7:04 am

Quoting Thorben (Reply 61):
Thorben From Germany, joined Sep 2005, 1310 posts, RR: 2
Reply 61, posted Wed

I just saw that Boeing posted a 15ea. 777 order! Yikes!!! How many widebodies have they sold this year? How many has Airbus? Like I said earlier. Prepare yourself to be cheerleading for an "almost ran"!

khobar · Fri Nov 17, 2006 7:47 am

Quoting 2wingtips (Reply 124):
Rubbish again. The list of Leahy quotes was first put on the "orders" forum some time ago, then it was put on "fleetbuzz" with permission. To post it here with no referencing is wrong. It's an open and shut case.

So, do you have a link to the "orders" forum where you say this list originated? If someone there is claiming copyright...

2wingtips · Fri Nov 17, 2006 8:08 am

Quoting Khobar (Reply 127):
So, do you have a link to the "orders" forum where you say this list originated? If someone there is claiming copyright...

Do you get it? Copyright is not the issue. Proper decency and acknowledgement is the issue. This should have been accompanying the initial post.
So, you say it's fine to swipe stuff if it isn't copyrighted and not acknowledge it? That's the way it sounds to me.

khobar · Fri Nov 17, 2006 10:15 am

Quoting 2wingtips (Reply 128):
Do you get it? Copyright is not the issue. Proper decency and acknowledgement is the issue.

Your comments are based on your personal feelings rather than facts. Yes, I do get it.

Quoting 2wingtips (Reply 128):
So, you say it's fine to swipe stuff if it isn't copyrighted and not acknowledge it? That's the way it sounds to me.

Swipe doesn't apply here.

Mr. Leahy did, in fact, make the claims quoted, and the material is, in fact, properly attributed.

NYC777 · Fri Nov 17, 2006 10:20 am

Well Let's put an end to this bickering:

Khorbar, thank you for your support. I appreciate it.

2wingtips, let's just agree to disagree and move on to discussing the issues and topics raised in various threads.

Agreed?

osiris30 · Sat Nov 18, 2006 1:15 am

Quoting Curmudgeon (Reply 123):
I think Osiris is saying that either its shattered, and requiring a section repair, or its only cosmetic, and requiring the equivalent of a tape job*

Basically yes that is why I'm saying. CFRP isn't going to suffer the minor dents and dings that affect AL skins. It may have a minor scrape or scratch or a much much larger issue. Perhaps shattered was the wrong word and splintered would have been better.

Quoting Curmudgeon (Reply 123):
Cracking isn't common, and the stiffness tends to distribute impact loads over a wider area, thereby resisting damage.

Exactly. A corner impacting AL might tear through the AL, but would require significantly more force to punch through the CFRP. For all the extreme examples folks are showing here, they are not the norm for aircraft. Things like wheels up belly landings should never happen and if they do the repairability of the plane is secondary to determining why it happened in the first place and prevent it in the future.

FINALLY, if there is a slightly higher attrition rate of in service craft due to EXTREME accidents, that is likely to be offset but aircraft staying in the fleet longer due to higher cycle limits, so at worst it's a wash for the airlines from a dollars and cents perspective. (although I would have to say in all honesty it works out much much more in favor of the airline)

Quoting Curmudgeon (Reply 123):
It is a little brittle though,

That's largely dependant on the design of the component. I would argue that Airbus's proposed CFRP panels are likely to be significantly more brittle than Boeings 1 piece contruction due to the nature of where stress will and won't be loaded.

halls120 · Sat Nov 18, 2006 1:24 am

Quoting Micstatic (Reply 114):
Quoting Halls120 (Reply 17):
You have to understand that in the US, being a sales person isn't exactly a respected occupation, no matter what you are hawking.

That's funny. Didn't realize lawyers were up there either?

Hell, my profession is probably LESS well regarded by the public.

At least we don't try to sell you something based on hype, smoke and mirrors. Wink

Quoting TeamAmerica (Reply 116):
Quoting AutoThrust (Reply 109):
Maybe sometime he will make a ludicrous Blog like Randy so you all can express your meanings about his person.

Ludicrous? I find Randy's blog quite interesting at times. I very much wish Leahy would post a blog. We might get his comments in a more thoughtful manner, with proper context. As it is, he seems to be the lone arrogant American who gets a pass from my European friends. Why is that?

I've wondered about this as well. With a blog, you get to but your message out under your control. You talk to a reporter, you run the risk your comments will be twisted way out of context.

Quoting Baroque (Reply 117):
Equally, anyone as apparently "bad" as Leahy must have something good going for him.

He's a great salesman - no one can contest that. It's the manner in which he operates that draws criticism. Are you suggesting that because he is a good salesman, his methods ought to be immune from scrutiny and comment?

Shenzhen · Sat Nov 18, 2006 1:55 am

Quoting Astuteman (Reply 125):
The second comes from the fact that, where the metal is perforated, it is by definition weaker than the parent plate. Hence it has to be thicker than if it wasn't perforated........hence the entire plate has to be thicker, as the plate will invariably be uniform thickness.

The entire plate (skin) is not the same thickness (uniform). Skins today are much thinner in the areas where it is not attached to underlying structure.

cheers

baroque · Sat Nov 18, 2006 1:55 am

Quoting Halls120 (Reply 132):
He's a great salesman - no one can contest that. It's the manner in which he operates that draws criticism. Are you suggesting that because he is a good salesman, his methods ought to be immune from scrutiny and comment?

Certainly not, just keep it above the belt and don't keep hitting the same place. One blow will do and then pass on to a new fault!

Otherwise you will get the Saddam syndrome! bigthumbsup

Shenzhen · Sat Nov 18, 2006 2:15 am

Quoting Osiris30 (Reply 131):
Exactly. A corner impacting AL might tear through the AL, but would require significantly more force to punch through the CFRP. For all the extreme examples folks are showing here, they are not the norm for aircraft. Things like wheels up belly landings should never happen and if they do the repairability of the plane is secondary to determining why it happened in the first place and prevent it in the future.

FINALLY, if there is a slightly higher attrition rate of in service craft due to EXTREME accidents, that is likely to be offset but aircraft staying in the fleet longer due to higher cycle limits, so at worst it's a wash for the airlines from a dollars and cents perspective. (although I would have to say in all honesty it works out much much more in favor of the airline)

If an airplane is struck by a ramp vehicle, and lets say two frames and 4 stringers are damaged (along with the skin), an airline could simply splice in the underlying damaged structure and install a patch (flush or scab) to the airplane, as is done today. There would probably be an unique inspection interval added to the airplanes scheduled maintenance, but they certainly wouldn't need to replace an entire barrel section, as some are aluding.

Mr. Leahy is playing to every airlines fear, that an airplane is suddenly grounded with unscheduled maintenance due to ground damage. I'm surprised that he isn't stating that Boeing composites are prone to a signifcant increase in unscheduled maintenance during the worlds holidays.

Cheers

[Edited 2006-11-17 18:23:06]

astuteman · Sat Nov 18, 2006 2:28 am

Quoting Shenzhen (Reply 133):
The entire plate (skin) is not the same thickness (uniform). Skins today are much thinner in the areas where it is not attached to underlying structure.

Grandmothers and eggs........

Don't dispute that. It's why I said "plate" and not "skin". But if metal's your material, in order to increase thickness in way of the underlying structure, you have to "overlap" your "thin" plate onto a "thicker" one in way of the underlying structure.

(Pretty much in the same way rivetted ships were built for a century or more, never mind "today". You think the SS Great Britain's "skin" is all one thickness? ... Smile

)

Metallic plates (steel OR aluminium) do not, in my experience, come from the mill with varying thicknesses on one plate.

But with a CFRP panel, you can vary the thickness on the same panel to suit the duty, something IMO that's impossible with a single piece of metal, without joins.

Regards

Shenzhen · Sat Nov 18, 2006 2:43 am

Quoting Astuteman (Reply 136):
Metallic plates (steel OR aluminium) do not, in my experience, come from the mill with varying thicknesses on one plate.

Skins are chemically milled and have varying thicknesses on one part number. There are only a few overlapping (lap) splices, that run the length of the fuselage. All other skin splices would butt up against one another.

Cheers

ikramerica · Sat Nov 18, 2006 2:44 am

Quoting Astuteman (Reply 136):
(Pretty much in the same way rivetted ships were built for a century or more, never mind "today". You think the SS Great Britain's "skin" is all one thickness? ... )

I spent the night on the Queen Mary this summer (original) and put my head out the porthole. I was surprised to see just how much overlapping of panels there was, and how thick the overlaps were. I was so used to seeing the smooth cruise ships of today that it was really cool to see just how rough and crude the old designs really were...

hb88 · Sat Nov 18, 2006 2:52 am

Quoting Osiris30 (Reply 131):
That's largely dependant on the design of the component. I would argue that Airbus's proposed CFRP panels are likely to be significantly more brittle than Boeings 1 piece contruction due to the nature of where stress will and won't be loaded.

and...

Quoting Katekebo (Reply 7):
From engineering point of view, making a fuselage with composite panels attached to a conventional frame makes little sense. The beauty of composites is that you can build complex geometrical shapes that are fully integrated from the structural point of view, allowinig the designer to achieve greater strength in the desired directions with less material (weight).

Greetings. True to a point (leaving aside the assumption that the 350 will include a conventional frame). But I wonder whether mandrel spun structures actually have more limitations in terms of layout (ie fibre orientation) and thus less structural flexibility than laid-up laminates. Using your words, the "desired directions" are more limited due to the physical limitations of the component spinning process itself. Spun CFRP is more suited to components with a high degree of axial symmetry in terms of loads - drive-shafts, fuel tanks, pressure vessels etc. While the fuselage is for sure a pressure vessel, it also has to withstand significant heterogeneous load distribution - not something which is ideal for a generally load-symmetric CFRP piece as you may need to build in additional structure where it's needed.

I see also that people have been writing off the panel approach as too expensive and somehow inferior. I'm not sure that's correct. I think discrete panel components are perhaps a more mature composite fabrication technology and maybe more resilient to manufacturing errors. If you get halfway through building a co-cured stringer/mandrel barrel component and stuff it up, that's significantly more expensive and difficult to retrieve that if a single panel is found faulty.

Of course I'm basing this on guesswork and I'm sure there's a loads/structures dude out there who can correct me. Personally, I find the panel thing a quite inelegant solution and the Boeing solution neater, but there might be more to the Airbus approach than meets the eye.

osiris30 · Sat Nov 18, 2006 2:59 am

Quoting HB88 (Reply 139):
Of course I'm basing this on guesswork and I'm sure there's a loads/structures dude out there who can correct me. Personally, I find the panel thing a quite inelegant solution and the Boeing solution neater, but there might be more to the Airbus approach than meets the eye.

Well I don't think Airbus's solution is horrible. I also don't think it's as good as Boeings. The simple fact of the matter is (at least in my view) there are going to be significantly more load/pressure bearing areas with the panel approach than the one piece approach.

The entire point of the one piece approach is that loading is equally and evenly distributed as there are no joint to bear the brunt of the force. This hold true regardless of the type of material that is being used. Connection points are stress points. The more connection points you have the more areas you have that can fail. Because you have more of these points and they bear the brunt of all the stresses you have to over build them so they do not fail.

That's the true shortcoming I see with the panel design. Not that composite panels are bad, just that single piece construction is better.

astuteman · Sat Nov 18, 2006 3:05 am

Quoting Shenzhen (Reply 137):
Skins are chemically milled and have varying thicknesses on one part number.

I stand corrected and educated, Shenzhen. Many thanks indeed checkmark

With welding the norm, and the thickness changes so large, chemical milling is something we just wouldn't do in shipbuilding, and I've never seen done (on structure anyway).

Quoting Ikramerica (Reply 138):
I was surprised to see just how much overlapping of panels there was, and how thick the overlaps were. I was so used to seeing the smooth cruise ships of today that it was really cool to see just how rough and crude the old designs really were

It's incredible, isn't it?
But weren't they magnificent? bigthumbsup

PROPER ships, not floating apartment blocks..... Smile

Regards

hb88 · Sat Nov 18, 2006 3:42 am

Quoting Osiris30 (Reply 140):
The entire point of the one piece approach is that loading is equally and evenly distributed as there are no joint to bear the brunt of the force. This hold true regardless of the type of material that is being used. Connection points are stress points. The more connection points you have the more areas you have that can fail. Because you have more of these points and they bear the brunt of all the stresses you have to over build them so they do not fail.

That's the true shortcoming I see with the panel design. Not that composite panels are bad, just that single piece construction is better.

True. I agree that introducing any form of joint is a bad thing - especially in a pressure vessel. Single piece is always better. But I wasn't really talking about interface or joint loads (leading to rupture damage). I was more referring to planar loads which will vary significantly around the fuselage.

For example, side loads due to side aerodynamic forces, twisting loads, asymetric gust loads, landing gear loads etc. My vocabulary is probably all wrong, but the loads from these forces and many others have a reaction component in the plane of the skin. So, if you have a fibre axis which is constrained due to the spinning process (ie, the fibres run 'around' the fuselage, or alternating slightly in the z direction in an offset), it means that the skin will be weaker for loads which have a component parallel to the axial direction of the fuselage.

Think of it like this: a classic flat laminate panel with uniaxial composite fibres has a highly non-isotropic load character - ie great in one direction, very poor in the other - this gives you the flexibility of designing the 3-d ply orientation to suit the specific anticipated loads. Curl that uniaxial flat panel into a cylinder perpendicular to the fibre axis. It will be an excellent pressure containment vessel, but attach levers (wings) at right angles to it. Twist them, and uh oh..

Maybe there are helical spinning techniques which can run the fibres significantly more parallel to the axis of the fuselage and ways of designing in very localised fibre orientation to take into account local loads - it would be interesting to see. But I doubt you could 'tune' your in-ply loads as easily as you could for a composite panel made the much less sexy conventional way. Alternatively, perhaps the spun barrel is simply so strong that load variation isn't important. I'm not sure.

ikramerica · Sat Nov 18, 2006 3:45 am

Quoting Astuteman (Reply 141):
PROPER ships, not floating apartment blocks.....

Agreed. I have a great picture taken from the porthole down the length of the ship.

that's a modern Carnival ship docked perpendicular, using the Long Beach terminal which is inside the dome that the Spruce Goose used to be exhibited.

You can see from that photo the concept of overlapping sheets and the inherent inefficiencies it would present even when done in a modern way. Being able to sculpt a ship or a plane out of fewer pieces, as from clay or molded of plastic, would lead to better structural optimization and lower weight.

As for the old style cruise ships...
The Disney ships are the only large new ships I know of that aspire to the classic aesthetic. They try to hide the apartment block shape while still offering balconies for most staterooms. Even inside, there are some "throwback" staterooms that aspire to the style of 80 years ago. I think they are called the Navigator staterooms.

http://disneycruise.disney.go.com/dcl/en_US/home/home?name=HomePage

[Edited 2006-11-17 19:51:25]

osiris30 · Sat Nov 18, 2006 4:04 am

Quoting HB88 (Reply 142):
True. I agree that introducing any form of joint is a bad thing - especially in a pressure vessel.

Ok.. one down LOL..

Quoting HB88 (Reply 142):
But I wasn't really talking about interface or joint loads (leading to rupture damage).

Damn I knew it wouldn't be that east LOL.

Quoting HB88 (Reply 142):
a classic flat laminate panel with uniaxial composite fibres has a highly non-isotropic load character - ie great in one direction, very poor in the other - this gives you the flexibility of designing the 3-d ply orientation to suit the specific anticipated loads.

Agreed.

Quoting HB88 (Reply 142):
Maybe there are helical spinning techniques which can run the fibres significantly more parallel to the axis of the fuselage and ways of designing in very localised fibre orientation to take into account local loads - it would be interesting to see.

It would seem possible, but I do not know the specifics of the process as I'm not working with it.

Quoting HB88 (Reply 142):
But I doubt you could 'tune' your in-ply loads as easily as you could for a composite panel made the much less sexy conventional way.

This I will agree with, but I would assume some of the loading is transfered to the frame on the panel approach (yes I know skins are load bearing these days Wink

) . Similarly I would assume some of the loading on the 787 (from items such as wings and landing, gear, etc.) is transfered through non-fusalge (non-barrel) structures. Just because there is a single piece fusalge body component doesn't mean it can't and isn't being reinforced with additional load bearing members where needed to stiffen/strengthen the overall design (wingbox, hardened connection points, etc).

I would be very surprised if there aren't additional components that are added after the fusalge is spun to reinforce it in various ways.

Quoting HB88 (Reply 142):
Alternatively, perhaps the spun barrel is simply so strong that load variation isn't important. I'm not sure.

I think it's a combination of the two. I think the barrel itself is probably stronger than a bolted together approach. From a rigidity standpoint I would take it as a given. Additionally, as I said you can add reinforcing members where necessary to deal wtih additional stresses. These reinforcing structures need not add much weight, and can likely be more finely tuned than those in a more traditional frame (due to the better starting point in terms of structural stability).

Basically I'm saying either approach will need some additionaly structural support. I'm also calling the additional support a wash between the two approaches. That leaves the inherent inferiority of a patch work model when dealing with a pressure vessel. To me that means the 787 approach 'wins'.

PS: It's always a pleasure to discuss things with you (please overlook any typos/spelling mistakes I'm at the office and rushing my post LOL). Sorry if this isn't my most coherent post ever.

hb88 · Sat Nov 18, 2006 4:16 am

Quoting Osiris30 (Reply 144):
This I will agree with, but I would assume some of the loading is transfered to the frame on the panel approach (yes I know skins are load bearing these days Wink ) . Similarly I would assume some of the loading on the 787 (from items such as wings and landing, gear, etc.) is transfered through non-fusalge (non-barrel) structures. Just because there is a single piece fusalge body component doesn't mean it can't and isn't being reinforced with additional load bearing members where needed to stiffen/strengthen the overall design (wingbox, hardened connection points, etc).

I would be very surprised if there aren't additional components that are added after the fusalge is spun to reinforce it in various ways.

So would I. I'd actually included something along these lines in my original draft post, but yanked it as it was getting too long Smile

I'd expect more internal structure in areas where a perhaps metal fuse wouldn't need it. I think I prefer the spun fuse approach if there aren't too many downsides in terms of the added structure and just as importantly in the industrialisation capability and in-service/manufacturing reliability. If you get that 100% right, it'll be sweet. For these reasons, to me it's perhaps not as evident that the Boeing approach wins hands-down. I personally think the panel approach is a conservative, but reliable and quick approach to including more composite in an aircraft and building a cfrp fuse. Remember, Airbus do have pretty fair long-standing experience in panel composites and bonding techniques have come a long way. So perhaps the interface issues might not be as problematic as one might intuitively think. Anyway, it'll be interesting to see how they compare over the life of the a/c and in service - assuming that the 350 is approved for launch of course!

Quoting Osiris30 (Reply 144):
PS: It's always a pleasure to discuss things with you (please overlook any typos/spelling mistakes I'm at the office and rushing my post LOL). Sorry if this isn't my most coherent post ever.

Likewise! It's a pretty coherent post to me - but then it's friday and my brain is making the long slow wind-down to the weekend.

Stitch · Sat Nov 18, 2006 4:27 am

I wonder if Boeing's technique "counter-layers" the CFRP so that rigidity in one layer is designed for certain loads while the next layer is designed to take other loads, and so on. Building-up on each other so that the whole is designed to take whatever loads in whatever directions are imposed upon it.

osiris30 · Sat Nov 18, 2006 4:32 am

Quoting HB88 (Reply 145):
If you get that 100% right, it'll be sweet.

Well you see that's where I'm confident Boeing has gotten it right. Being the first company to try this they knew they couldn't make mistakes. I expect the 787 will get even lighter over future generations. I'm guessing Boeing has way overdone certain areas to be safe.

Quoting HB88 (Reply 145):
Remember, Airbus do have pretty fair long-standing experience in panel composites and bonding techniques have come a long way. So perhaps the interface issues might not be as problematic as one might intuitively think.

Perhaps not, but I can guarantee that any bonded joint (regardless of method of joining) will require inspection over time, while I don't think the single piece skins of the 787 will. So this, again to me, is the winner.

Quoting HB88 (Reply 145):
Anyway, it'll be interesting to see how they compare over the life of the a/c and in service - assuming that the 350 is approved for launch of course!

Agreed and who knows. Maybe Airbus is right here, but frankly everything I ever learned, in school or from other engineers tells me the Boeing approach is the 'right way' at the end of the day.

Quoting HB88 (Reply 145):
but then it's friday and my brain is making the long slow wind-down to the weekend.

Lucky SOB. I get to manage a boys hockey team on weekends LOL

osiris30 · Sat Nov 18, 2006 4:34 am

Quoting Stitch (Reply 146):
I wonder if Boeing's technique "counter-layers" the CFRP so that rigidity in one layer is designed for certain loads while the next layer is designed to take other loads, and so on

I'm not sure that wouldn't create more issues with internal sheering than it would solve. But again I don't know the specifics of their process to truly comment.

Stitch · Sat Nov 18, 2006 4:42 am

Quoting Osiris30 (Reply 148):
I'm not sure that wouldn't create more issues with internal sheering than it would solve. But again I don't know the specifics of their process to truly comment.

Nor do I. I am aware that many CFRP composites are very strong when stressed in one direction, yet very fragile when stressed in another. Formula One wishbones, for example, can take amazing vertical loads thanks to the orientation of the fibres but even a light shunt that inputs minimal lateral loads shatters them into a million pieces.

hb88 · Sat Nov 18, 2006 5:02 am

Quoting Osiris30 (Reply 148):
Quoting Stitch (Reply 146):
"I wonder if Boeing's technique "counter-layers" the CFRP so that rigidity in one layer is designed for certain loads while the next layer is designed to take other loads, and so on"

I'm not sure that wouldn't create more issues with internal sheering than it would solve. But again I don't know the specifics of their process to truly comment.

If you can't do this, you lose one of the big advantages of designing with laminates, isotropic load tailoring for panel load dissipation. I guess it depends on the helicity of the fibre application and how discontinuously the process could be run. If you can do a 0 degree layer, then a +/-45 degree (or whatever layer), then you could make a skin with something like the 'usual' macro laminate structure. But the barrels are pretty short from memory and your fibre application mechanism would have to make some fairly sharp diversions.

Actually, I just checked and seems that they can lay individual tows at essentially any angle on the barrel by starting, stopping and cutting the laid tow discontinuously as the barrel is spun. So that may be how local load tailoring is done as the impregnated fibre bands are laid.

Areopagus · Sat Nov 18, 2006 8:07 am

Quoting HB88 (Reply 142):
Maybe there are helical spinning techniques which can run the fibres significantly more parallel to the axis of the fuselage and ways of designing in very localised fibre orientation to take into account local loads

There is a movie of automated tape laying for the 787 available at
http://a825.v81539.c8153.g.vm.akamai...om/media/wmv/2005-01/15818092.wmv. In the clip depicting flat layup, the tape applicators are seen to swivel and move in various directions. In the section showing layup on the 787 fuselage mandrel, the applicator is holding nearly steady while the mandrel turns, so that the fibers are laid circumferentially. This is the best direction for pressurization loads. But for a long tube supported by a wing in the center, the sagging loads run along the length of the fuselage, particularly on the top and bottom. I'm sure they run the tape applicators longitudinally. And again, to counter sag, they must also be laying fibers diagonally as well.

There is additional structure built into the barrel. The mandrel has slots for stringers that are laid in. Mike Bair said (reported in Flug Revue):

“First you wind it round, then you insert the stringers, then you wind it some more, then finally everything goes into the oven and is baked for eight hours like a turkey. Window and door openings can then be added afterwards, rather like cutting out biscuits,” Bair enthuses, rather like a chef. Only the frame assemblies are mechanically inserted at the end.

So, while the barrel ends up as a single part without fasteners, it contains components (also CFRP) that are made separately and then integrated into the structure and cured into it.

osiris30 · Sun Nov 19, 2006 3:02 am

Quoting HB88 (Reply 150):
Actually, I just checked and seems that they can lay individual tows at essentially any angle on the barrel by starting, stopping and cutting the laid tow discontinuously as the barrel is spun. So that may be how local load tailoring is done as the impregnated fibre bands are laid.

Sounds like they are way ahead of us LOL. If they can really pull it off, they are miles ahead IMHO. You know some guys lost a lot of sleep over these issues we idly debate Smile

Poitin · Sun Nov 19, 2006 3:25 am

Quoting Astuteman (Reply 136):
Don't dispute that. It's why I said "plate" and not "skin". But if metal's your material, in order to increase thickness in way of the underlying structure, you have to "overlap" your "thin" plate onto a "thicker" one in way of the underlying structure.

Quoting Astuteman (Reply 136):
Metallic plates (steel OR aluminium) do not, in my experience, come from the mill with varying thicknesses on one plate.

Quoting Shenzhen (Reply 137):
Skins are chemically milled and have varying thicknesses on one part number. There are only a few overlapping (lap) splices, that run the length of the fuselage. All other skin splices would butt up against one another.

While chemical milling of aluminium skins was first used on the B 29, the A380 uses good old mechanical milling. The Discovery Channel did an hour long show on the making of the A380 wings in Wales. A 90 foot long AL-LI plate comes in, and dropped in a vertical surface milling machine with a lengh of about 40 meters, and it then precision mills the skins down to the nearest hundredth of a millimeter. Once that is done the skin is "cheep formed" in a autoclave.

The big breakthrough for the wing is the development of laser welding which permits the welds to be as strong or stronger than the metal itself.

Can't take anything away from Airbus or the people in Wales. They know what they are doing. If you get a chance to see the show, so so. It is a part of a three part series they did a couple years ago.

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