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Safety of CFRP-constructed 787?  
User currently offlinerevo1059 From United States of America, joined Mar 2006, 132 posts, RR: 0
Posted (3 years 3 months 2 weeks 1 day 9 hours ago) and read 7590 times:

Let me make this perfectly clear, this is NOT a dig at BOEING at all.


I love flying and have never been fearful of it.......but.......

The 787 is a completely new way of making a plane and what it is made of. With the current metal planes having been around for as long as they have most of the kinks have been worked out. A CF passenger plane does make me a little wary of how it will hold up long term and how it will tolerate various stresses.

One thing that comes to mind is the Southwest plane that lost some skin or the UA plane that blew out part of it's fuselage. Metal stresses differently, it can actually bend, stretch and give signs before it fails. I don't believe CF can do that. It's either intact or in a million pieces. Experts have decades of real world data on how todays planes react as they age and that has come from some hard lessons learned.

I'm not afraid (way too strong of a word)per se, and when I have the chance to ride the 787 I will gladly take my seat, but with such a new way of building a plane and the materials used, it does make me wonder just a little bit........

80 replies: All unread, showing first 25:
 
User currently offlineStitch From United States of America, joined Jul 2005, 30922 posts, RR: 87
Reply 1, posted (3 years 3 months 2 weeks 1 day 9 hours ago) and read 7508 times:
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Well we've had large composite structures in military planes for some time and they seem to hold it together, so I'm not going to worry about it. CFRP, Al or wood and fabric, it's out of my hands, anyway.  

User currently offlinepar13del From Bahamas, joined Dec 2005, 7152 posts, RR: 8
Reply 2, posted (3 years 3 months 2 weeks 1 day 9 hours ago) and read 7338 times:

Well that's one less person to ride on the A380, my chances have improved.  

You do know that prior to the 787 the largest piece of composite material was in the A380 right, and no it was not involved in the QF incident.


User currently offlineXT6Wagon From United States of America, joined Feb 2007, 3401 posts, RR: 4
Reply 3, posted (3 years 3 months 2 weeks 1 day 8 hours ago) and read 7093 times:

you have been riding in planes that would crash with the failure of thier composite structures for decades now.

Vertical and horizontal stabilizers have been composite for quite some time.


User currently offlineJBirdAV8r From United States of America, joined Jun 2001, 4489 posts, RR: 21
Reply 4, posted (3 years 3 months 2 weeks 1 day 7 hours ago) and read 6920 times:

Quoting revo1059 (Thread starter):
Metal stresses differently, it can actually bend, stretch and give signs before it fails. I don't believe CF can do that. It's either intact or in a million pieces.

That's not exactly true.

Carbon Fibre Reinforced Polymer, while never used to the extent that it is on the 787, has been used by Airbus, Boeing and most other aviation manufacturers for decades on more critical parts than the fuselage. You find them in jet fighters that can easily take many times the loads ever expected in a commercial jetliner--and they've been in service for many years.

In my experience (maybe it's just me) people think of CFRP the same way they think of fiberglas. And this is most definitely NOT fiberglas.



I got my head checked--by a jumbo jet
User currently offlinenomadd22 From United States of America, joined Feb 2008, 1858 posts, RR: 0
Reply 5, posted (3 years 3 months 2 weeks 1 day 7 hours ago) and read 6830 times:

There's a reason they've been torturing two test frames. The static frame held up to more than any plane will ever see short of crashing and they'll continue to abuse the fatigue frame until it's had more bending and stretching than Joan Rivers' face. They don't just pick a new hull and start flying passengers on it.
And your logic is a little peculiar, since both incidents you referred to are proof that you often have no warning whatsoever of aluminum failure.



Andy Goetsch
User currently offlinegoblin211 From United States of America, joined Jun 2010, 1209 posts, RR: 0
Reply 6, posted (3 years 3 months 2 weeks 1 day 7 hours ago) and read 6819 times:

Quoting JBirdAV8r (Reply 4):
. And this is most definitely NOT fiberglas.

If it was, I sure as heck wouldn't risk my life on it, not that the FAA would even approve such a thing.
Think of it this way revo1059, if it wasn't safe the FAA wouldn't approve of it and there wouldn't be any testing.



From the airport with love
User currently offlinemrskyguy From United States of America, joined Aug 2008, 1214 posts, RR: 3
Reply 7, posted (3 years 3 months 2 weeks 1 day 7 hours ago) and read 6757 times:

I don't mean to rain on the OP's parade, but isn't this thread just a bit of a step in to the ridiculous? The 787's up to 1,266 flights and 3,501 hours. The A380's been flying since April of 2005. And decades before that, CFRP has been used in many applications in aircraft.


"The strength of the turbulence is directly proportional to the temperature of your coffee." -- Gunter's 2nd Law of Air
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 8, posted (3 years 3 months 2 weeks 1 day 7 hours ago) and read 6604 times:

Quoting revo1059 (Thread starter):
The 787 is a completely new way of making a plane and what it is made of.

It's only new for commercial aircraft...the material and style of construction is decades old.

Quoting revo1059 (Thread starter):
A CF passenger plane does make me a little wary of how it will hold up long term and how it will tolerate various stresses.

The 777 uses exactly the same materials in its tail (one of the more highly loaded structures on the plane) and floor and is going on 15 years. It's "new" that the material is now being used for fuselage skin but, to some extent, stress is stress so the material properties and aging are *very* well characterized by now.

Quoting revo1059 (Thread starter):
One thing that comes to mind is the Southwest plane that lost some skin or the UA plane that blew out part of it's fuselage.

That's actually a type of failure that's nearly impossible to have in composites.

Quoting revo1059 (Thread starter):
Metal stresses differently, it can actually bend, stretch and give signs before it fails. I don't believe CF can do that. It's either intact or in a million pieces.

CFRP can bend and give signs before it fails. It does stretch, but elastically. The major difference between CFRP and aerospace alloys is that CFRP has a very small gap between yield strength (where it starts to permanently deform) and ultimate strength (where it breaks). But, since all aircraft design is done assuming that you never go above yield strength in the life of the aircraft, there shouldn't be any noticeable different in material behavior in normal use. It's only *after* you overstress the airframe that the differences show up.

Quoting revo1059 (Thread starter):
Experts have decades of real world data on how todays planes react as they age and that has come from some hard lessons learned.

This is equally true of CFRP as it is for alloys. From a pure materials standpoint, the GLARE on the A380 is more risky than the CFRP on the 787 or A350. I'm *not* suggesting there's anything wrong with GLARE, just that's it's got a much smaller history in aviation use than CFRP.

Tom.


User currently offlineFX1816 From United States of America, joined Mar 2004, 1400 posts, RR: 4
Reply 9, posted (3 years 3 months 2 weeks 1 day 6 hours ago) and read 6571 times:

Quoting revo1059 (Thread starter):
or the UA plane that blew out part of it's fuselage.

Do you mean the UA 747 that had a hole rip open in it after departing HNL? If so I don't really believe that the type material the fuselage is made of would matter at all in this case given that an electrical short caused the door to open up in mid flight and that is why it ripped a hole in the plane.

FX1816


User currently offlineEASTERN747 From United States of America, joined Oct 2006, 541 posts, RR: 0
Reply 10, posted (3 years 3 months 2 weeks 1 day 6 hours ago) and read 6493 times:

We have to remember the very first aircraft were wooden timbers held together with wire......the next generation, I believe was a wood frame covered in canvass.....then on to tin and eventually steel aluminmum etc. I'm always amazed that everytime I board an aircraft, I look at the door frame and see how thin the skin really is. I believe it's time to move on and search for new products that mean greater safety and economics.I remember in the 50's-60's-70's having to buy a car every 5-6 years because they broke down, rusted, etc. I now drive an 02 car without a single spot of rust. The paint looks brand new and it still has had no problems. (knock on wood). My point is these new aircraft will carry use to the middle of this century, and with that point change... is good.

User currently offlinesoon7x7 From , joined Dec 1969, posts, RR:
Reply 11, posted (3 years 3 months 2 weeks 1 day 4 hours ago) and read 6237 times:

Last month I was given two wingtips from the horizontal stab of a very popular regional jet to topcoat as these were new replacements for eroded carbon fibre older flown ones. I was shocked at the level of leading edge erosion on the used components, almost 80% penetration. Had these leading edges had metallic leading edges I would not have been requested to topcoat new replacements. The closest eroded metallic ecquivalent I have seen was from a 30 year old US Air DC-9 30...not a 5 year old N/G regional. While I highly regard Tdscanuck responses I beg to differ on CFRP's ability to warn of failure...that is the one undesirable characteristic of the material is that when it fails it is usually catastrophic and immediate. While the material has been used in many forms over decades to my knowledge it has never been used to create the torque box of a major transport aircraft such as the 787. While jet fighters, military hilos and various heavy transport aircraft utilize the material, the load demands of a main wing are far different than vertical fins, tail cones,...etc. As much as I love the science of composites, I still believe that over time we will learn once again the limits of certain material applications. By the way...fibre glass is still widely used in the production of transport aircraft. Epoxy is the binder...not polyester resins. One more point...an International council exists that has an annual meeting and produces a book annually that focuses on the limits of fabrication with CFRP's. I purchased the book...much$$$,...I understand about 30% of it as I am not a physicists. Still trying to sort through it but the base concern is that the industry recognizes the materials shortcomings in predictability...in short.

User currently offlineStitch From United States of America, joined Jul 2005, 30922 posts, RR: 87
Reply 12, posted (3 years 3 months 2 weeks 15 hours ago) and read 6130 times:
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Well if CFRP is not safe, the 787 and A350 are going to cause Boeing and Airbus a great deal of grief.

But if both of them liquidate, at least we'll have United Aircraft Corporation to pick up the slack and deliver good ol' aluminum airliners.  


User currently offlinesoon7x7 From , joined Dec 1969, posts, RR:
Reply 13, posted (3 years 3 months 2 weeks 10 hours ago) and read 6047 times:

I recently read an article in Aviaition Week regarding the production of a Chinese regional jet...the type and name escapes me as I must find the article as some will demand I show" references"...however, the article went on to state that the producers have opted for conventional alloy construction over composites as the weight penalty was neglagable, the production would be easier and less expensive and faster. No doubt that this RJ will have composites in its design but not as primary structure...according to the article. Don't get me wrong...I champion composites as the process is an engineering marvel. What other product takes spools of filament, rolls of fabric, impregnates them with liquid and Bingo!...an aerodynamic, thermal resistent structure that can and will endure incredible punishment. I just believe the product has a limit that no one has quite put their finger on yet, regarding cycles, mass, etc. As primary structures CFRP's in heavy Iron, Uh...heavy plastics, is sort of in its infancy relatively speaking.

User currently offlineStitch From United States of America, joined Jul 2005, 30922 posts, RR: 87
Reply 14, posted (3 years 3 months 2 weeks 10 hours ago) and read 6030 times:
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Quoting soon7x7 (Reply 13):
I recently read an article in Aviaition Week regarding the production of a Chinese regional jet...the article went on to state that the producers have opted for conventional alloy construction over composites as the weight penalty was neglagable, the production would be easier and less expensive and faster.

Probably the Comac ARJ21. And the Comac C919 narrowbody will also be made mostly of aluminum. And for a "new entrant", it makes sense to stick with "known technologies" and not take additional risks with new materials.


User currently offlineSEPilot From United States of America, joined Dec 2006, 6899 posts, RR: 46
Reply 15, posted (3 years 3 months 2 weeks 5 hours ago) and read 5954 times:

I believe that CFRP will, if anything, improve crash survivability. Formula 1 cars have incorporated a safety cell made largely of CFRP, and it has proven quite effective. The point is that CFRP will absorb a large amount of energy, and then shatter without significant defomation, while metal will deform to absorb energy and more likely than not crushing any occupants.


The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlinesoon7x7 From , joined Dec 1969, posts, RR:
Reply 16, posted (3 years 3 months 1 week 6 days 18 hours ago) and read 5901 times:

Quoting Stitch (Reply 14):
and not take additional risks with new materials.


Yes, the article stated that having witnessed the "problematic forward motion of major contractors development progress"...they will opt for "conventional alloy construction".

Quoting SEPilot (Reply 15):


In an unfortunate way...it will be interesting to see how your theory plays out in the future...One of my clients currently flies two models from one manufacturer and their pilots state that when landing, the CFRP airframe has a much more pronounced contact with the runway while the alloy airframe is softer. They note that the contact force travels through the entire airframe suddenly rather than softly being absorbed by the conventional airframe (aluminum).

Quoting SEPilot (Reply 15):
while metal will deform


You mean..."the Mercedes Crumple Zones?"...another word for..."we're using thinner guage metals!...I love the spin...   


User currently offlineSEPilot From United States of America, joined Dec 2006, 6899 posts, RR: 46
Reply 17, posted (3 years 3 months 1 week 6 days 6 hours ago) and read 5800 times:

Quoting soon7x7 (Reply 16):
One of my clients currently flies two models from one manufacturer and their pilots state that when landing, the CFRP airframe has a much more pronounced contact with the runway while the alloy airframe is softer.

How much of this is influenced by the fuselage material, and how much by the landing gear design? I'm not saying that the fuselage might not have the effect you describe, but the landing gear tuning might also have a substantial effect. And this does not really mean anything in terms of the performance in a crash.



The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlineaklrno From United States of America, joined Dec 2010, 934 posts, RR: 0
Reply 18, posted (3 years 3 months 1 week 6 days 5 hours ago) and read 5779 times:

Quoting SEPilot (Reply 15):
I believe that CFRP will, if anything, improve crash survivability. Formula 1 cars have incorporated a safety cell made largely of CFRP, and it has proven quite effective. The point is that CFRP will absorb a large amount of energy, and then shatter without significant defomation, while metal will deform to absorb energy and more likely than not crushing any occupants.

The CFRP tub that the driver sits in neither deforms nor shatters if things go correctly. That is the whole point. The energy is lost by the deformation and then departure of nearly everything attached to the tub. There have been several well publicized crashes of Ferrari Enzos which are built the same way. The drivers walked away. The car was collected from the surrounding area and sent to the dump in small pieces.

Quoting soon7x7 (Reply 16):
Quoting SEPilot (Reply 15):
while metal will deform


You mean..."the Mercedes Crumple Zones?"...another word for..."we're using thinner guage metals!...I love the spin...   

Instead of cynicism, try leaning a little engineering. The crumple zones work beautifully . In the old days when thicker steel was the norm, the death rate was much higher. The car was often repairable by the late driver's estate. As in my comment above, the current idea is for as much energy as possible to be absorbed by the frame. To insure this, the frame has areas where members are intentionally weakened by a bit of accordion folding so that the engineers can choose where the deformation occurs. Thin steel may save some money, but it also allows the crumple to work better.
The car is easily totaled, but more passengers survive.

The lighter steel also makes everything else in the car lighter, making everything cost less and reduces driving costs. Lest someone say that lighter cars are more dangerous, please note the death rates are lower because of things like crumple zones.

Too bad that doesn't work well for airplanes. Too much energy for the amount of frame and a lot of fuel.


User currently offlinebikerthai From United States of America, joined Apr 2010, 2107 posts, RR: 4
Reply 19, posted (3 years 3 months 1 week 5 days 15 hours ago) and read 5673 times:

Quoting revo1059 (Thread starter):
Southwest plane that lost some skin

The Southwest plane lost some skin because of improperly drilled rivet hole that failed and caused propagation of the failure along the fastener line. With the 787, there are fewer fastener lines to fail and in CFRP cracks do not propagate.

1) Cracks that starts in the matrix usually stops at the fiber/matrix interface.
2) Cracks that breaks a fiber doesn't do a whole lot because in the nature of the composite, the load is sheared into the matrix and around the broken fiber to the other side. (this is why composite is almost immune to fatigue crack propragation)

The one thing you have to worry about is potential delamination and propagation. Specially for bonded stiffeners. This will be proven out the next few years.

The other things that CFRP designer needs to worry about is the corrosion on any aluminum component mating up with CFRP parts. But as other here have noted. This is a known issue and is being addressed through proper galvanic isolation.

bikerthai



Intelligent seeks knowledge. Enlightened seeks wisdom.
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 20, posted (3 years 3 months 1 week 5 days 8 hours ago) and read 5594 times:

Quoting soon7x7 (Reply 11):
While the material has been used in many forms over decades to my knowledge it has never been used to create the torque box of a major transport aircraft such as the 787.

777 vertical and horizontal fin, A300/310 (and I think most of the subsequence Airbii) empennage. All primary structure torque boxes. And the loading on the horizontal fin is exactly the same as the wing from a stress point of view.

Tom.


User currently offlineStitch From United States of America, joined Jul 2005, 30922 posts, RR: 87
Reply 21, posted (3 years 3 months 1 week 5 days 8 hours ago) and read 5592 times:
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A significant part of the A380's wingbox is also made from CFRP. I've stood next to one and it's powerfully impressive (doubly so when they rolled an A320 wingbox up next to it).

User currently offlinebikerthai From United States of America, joined Apr 2010, 2107 posts, RR: 4
Reply 22, posted (3 years 3 months 1 week 4 days 11 hours ago) and read 5475 times:

Also, composite floor beams seems to be the norm now for large aircraft.

bikerthai



Intelligent seeks knowledge. Enlightened seeks wisdom.
User currently offlinePolymerPlane From United States of America, joined May 2006, 991 posts, RR: 3
Reply 23, posted (3 years 3 months 1 week 4 days 11 hours ago) and read 5471 times:

Quoting soon7x7 (Reply 11):
Last month I was given two wingtips from the horizontal stab of a very popular regional jet to topcoat as these were new replacements for eroded carbon fibre older flown ones. I was shocked at the level of leading edge erosion on the used components, almost 80% penetration

The leading edges of 787 will be metal

Quoting soon7x7 (Reply 13):
I recently read an article in Aviaition Week regarding the production of a Chinese regional jet...the type and name escapes me as I must find the article as some will demand I show" references"...however, the article went on to state that the producers have opted for conventional alloy construction over composites as the weight penalty was neglagable

That is only true for smaller aircrafts. IIRC McNerney admitted as much when discussing the 737 replacement.

Quoting SEPilot (Reply 15):
I believe that CFRP will, if anything, improve crash survivability. Formula 1 cars have incorporated a safety cell made largely of CFRP, and it has proven quite effective. The point is that CFRP will absorb a large amount of energy, and then shatter without significant defomation, while metal will deform to absorb energy and more likely than not crushing any occupants.

F1 survivability is related more to the honeycomb structure than the materials itself. CFRP might enable the honeycomb structure production, but the source of the strength is not CFRP



One day there will be 100% polymer plane
User currently offlineSEPilot From United States of America, joined Dec 2006, 6899 posts, RR: 46
Reply 24, posted (3 years 3 months 1 week 4 days 6 hours ago) and read 5428 times:

Quoting PolymerPlane (Reply 23):
F1 survivability is related more to the honeycomb structure than the materials itself. CFRP might enable the honeycomb structure production, but the source of the strength is not CFRP

I'm not so sure. I see it as a major advantage that CFRP will shatter rather than deform; this enables it to absorb and dissipate energy without collapsing the survival space of the occupants. How many car and aircraft crashes have caused the death of the occupants because they were crushed inside the passenger compartments? With CFRP the structure itself will not be deformed to the point of crushing the occupants; it will shatter instead. The occupants may still be killed by debris, by the force of the collision, or by other means, but I hold that they will have an additional chance of survival.



The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
25 aklrno : I'd like to hear from an engineer who is up to date on crash protection before believing that is correct. The number of pieces that result from the i
26 SEPilot : On a frontal collision this is usually correct. However, other accidents T-bone and rollovers in particular, often do involve crushing the occupants.
27 tdscanuck : After carbon fiber cracks, *lots* more energy can be absorbed. The "shattering" process is really the disbonding of bazillions of fiber/matrix interf
28 bikerthai : From my previous experience, composite (including honeycomb) does absorb a lot of energy. However, the point of failure is really unpredictable (larg
29 soon7x7 : I compared the Vertical fin loads to Main wing loads...not to H/stabs. However,...H/stabs with their smaller relative area would be better suited for
30 XT6Wagon : One of the reasons it hasn't been used earlier is that a skin that can take the abuse that wings take... from fueling and other servicing means a ski
31 bikerthai : We all know the efficiency of CFRP, but one thing that has kept CFRP from achieving their touted efficiency on a commercial airline wing is the inabi
32 rheinwaldner : But where do the shatters go? Clouds of razor baldes shooting through the cabin may negate the bonus of the "softer" impact.... I think of the Turkis
33 justloveplanes : I am still curious about the ability of an all composite airliner to withstand lightning strikes as my primary area of potential concern. I have heard
34 tdscanuck : They don't really go anywhere..."shatter" isn't the right word. What happens is the matrix comes apart and generally ends up nearly powdered, and the
35 Post contains images soon7x7 : The entire focus of why major transports are currently transitioning to CF structures has only one goal. To create a fuel efficient machine that can t
36 Starlionblue : soon7x7, I understand your viewpoint. However I have two comments: - Certification requirements are tougher than ever. I doubt a 707 or a 727 would be
37 tdscanuck : No doubt about it...you couldn't certify a 757/767 as-is today. Tom.
38 Post contains images Starlionblue : OMG they're deathtraps!
39 Stitch : That goal has been in place since the dawn of commercial aviation. It's why we make airliners today out of light, thin sheets of aluminum that crumpl
40 Starlionblue : I think at that point the material becomes pretty academic.
41 Post contains links and images XaraB : http://www.youtube.com/watch?v=cJrXViFfMGk&feature=related Have a look at how effective "thicker steel" is compared to crumple zones. Note the dif
42 TSS : Interesting. Once I got past the idea that someone would purposely trash a '59 Chevrolet that appeared to be in remarkably good shape, I couldn't hel
43 justloveplanes : Safety is a huge selling point in today's airliners. The latest gen airliners (777, 340, 767, 380) are much much safer than your ride to the airport.
44 SEPilot : But the safety that sells is aircraft that don't crash at all. Seeing as how many recent airliners have gone well over a decade before the first one
45 Post contains images Starlionblue : So basically we should give the Mythbusters a 787, have the fill it with pig carcasses, and take a road trip to Edwards AFB.
46 Post contains images SEPilot : Not a bad idea at that.... But seriously, no matter what we can theorize about, the question will only be answered when the first survivable crash of
47 aklrno : And we could fill some of the fuel tanks with barbeque sauce for a tasty treat after the test. Maybe it is time for dinner.
48 Starlionblue : Thanks for that image... Eeeeeewwww.
49 JayinKitsap : The OP is basically taking the position that New is Bad, and that the testing that goes into certification means nothing. It also discounts the fact t
50 Starlionblue : You are completely correct about Chinese quality control. The industrial/corporate culture necessary to produce this kind of component is simply not
51 bikerthai : Maybe you should add Japan into the exception of countries capable of fielding a modern blue water navy. I suspect Korea can also field one if they w
52 bikerthai : Japan and Korea has both. bikerthai
53 Starlionblue : You are of course correct. Just to be clear, I was in no way implying that the West is somehow superior. Just that China does not currently have thes
54 Post contains links Wingscrubber : Actually, HIRF testing on composite airframes is much more stringent than metal airframes. More conduction paths to think about, no faraday cage prot
55 Post contains links tdscanuck : Absolutely agreed. I wasn't trying to suggest that it's easy, just that the engineering does work and we've had composite airliners hit by lightning
56 SEPilot : The safety record of Cirrus aircraft has little to do with the composite construction. The crashes that have killed people would have likely had the
57 bikerthai : As for China, I agree with you on how the culture impacts the product. To see this for your self, visit your local Chinese grocery store, Korean groc
58 nomadd22 : Aluminum airliners are not "Faraday cages" The windows are far larger than the wavelengths of the high frequency stuff they worry the most about now
59 Post contains images bikerthai : Unless you treat the windows with EMI protections. There are various way to do that. Graphite can be good at EMI protection. The trick is to get cond
60 Post contains images Starlionblue : Agreed. I live in Hong Kong so am quite "exposed" to Mainland Chinese products. The tainted food scandals just keep on coming... Many expats simply j
61 rwessel : Not actually true of the 767 (first flight on 9/26/81, Lauda 004 on 5/26/91).
62 Wingscrubber : You sound like you must have certified a lot of components for composite airplanes... I'll concede to your greater wisdom. Then I shall demystify: Hi
63 nomadd22 : I remember thinking that the often quoted story that the CFRP skin increased in weight because engineers "discovered" they needed to add the mesh for
64 tdscanuck : It's an excellent conductor, but the resistance is too high to effectively dissipate lightning currents without damage...hence the mesh. Any time you
65 Post contains images bikerthai : Also consider that a typical carbon fiber weave or fill consists of many very small strand. With copper bundles, it is OK because the strands are tou
66 nomadd22 : Thanks. That answers a few questions about charge buildup within the stuff. Not enough conductivity to keep voltage differences down in high current
67 Raptor1090 : IM and HS carbon fibre composites are 7x stronger, 2x stiffer and 1.5x lighter than 6061 Aluminium (Grade of Aluminium usually used to make fuselages
68 Post contains links dynamicsguy : Ummm, no. Try 2024 for the fuselage of airliners, going back to the 707, and 2524 with 7150 stringers for the 777 (Source). You'll find various 2000
69 Raptor1090 : Well yes, you are right. But my point was to show the contrast between the two. The source I got it from had 6061 alloy as the comparison, and I didn
70 PITingres : Is there a link or non-metallurgist's explanation of the various alloy series and their contents / properties / differences for the curious layman?
71 Post contains links tdscanuck : MMPDS-01, METALLIC MATERIALS PROPERTIES DEVELOPMENT AND STANDARDIZATION http://www.everyspec.com/FAA/FAA+-+G...FAA-AR-MMPDS-01-JAN2003.024102.pdf (fo
72 bikerthai : The interior side paneling are not structural and do not contribute to the strength of the fuselage. In fact, the side panel installation are design
73 TSS : As I had suspected, considering the number of misaligned or loose interior side panels I've seen on various aircraft over the years. There was even a
74 Post contains images bikerthai : I just bring my own ear plugs and over ears head phones. And if it gets really bad, I turn up the volume. Most of the times, it's just a few screws a
75 Raptor1090 : Agreed. But what I meant is that they help in crash survivability, not that they are part of the fuselage. Just that they have a capacity to absorb i
76 bikerthai : Depending on what type of impact you are talking about. The panel would protect the passenger from hitting their head against the metal frames and st
77 Post contains images Raptor1090 : Hmmm... well you can't really predict that, but may sure be a possibility. If a composite fuselage, it'll fail in a brittle manner, so IMO, I don't t
78 larshjort : If the panels aren't attatched anymore, as the srews has been teared out, how will the panel absorb the energy if it isn't connected to anything? /La
79 Raptor1090 : In a hypothetical crash, the impact force direction would be from the fuselage to the panel. It's being pushed towards anything that's on the inside.
80 bikerthai : I guess we are getting confused with the mode of failure. The fuselage failure I was thinking is the typical fuselage break cause by over bending or
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