Dreamliner suffers another setback

reply to post by luxordelphi


No, they're done with computer models. Huge difference.

reply to post by luxordelphi

It uses a lot more aluminum and the fuselage composition is completely different

The A350 XWB uses less aluminium than the 787. Both use CFRP fuselages. The biggest difference is that each fuselage section in the A350 is made up of four panels, instead of being a single barrel.

In other words, they're done on paper.

Welcome to engineering. A lot of things are done on the computer or on paper. Also these tests were not done on paper or on a computer, they were done with real hardware, but on a smaller scale than reality.


Also almost all the current problems related to the 787 involve the new electrical architecture or the supply chain, rather than the composite materials. Also if new composite materials come out every several years and need to be recertified, then good. Recertify them.

reply to post by luxordelphi


Because if you have a composite material that uses a lot of plastic, then you add graphite to it, it's a new material. You have to recertify the material because you just radically changed the material. You think aviation is the only industry it happens in? Any industry that changes the makeup of a material has to certify the new material.

As for how long they've been in use Airbus has used a relatively high level of composites almost from the start with their first aircraft.

reply to post by C0bzz


I see that you edited your post but I'm going to reply to the pre-edited version anyway because I think that condensation with ultra-thin copper-aluminum wire is a factor. It is the synergy between the composite and the wire that I'm looking at.

Boeing Shares Drop After Boeing Reported Composite Structural Issues In The 787

Carbon fiber, unlike metal, does not visibly show cracks and fatigue, which has prompted concerns about the safety risks of widespread use of the material the rival Airbus A350 was later announced to be using composite panels on a frame, a more traditional approach, which its contractors regarded as less risky.

In addition, the porous properties of composite materials, which may cause delamination as collected moisture expands with altitude, is a potential issue. Delamination is a mode of failure for composite materials. Modes of failure are also known as 'failure mechanisms'. In laminated materials, repeated cyclic stresses, impact, and so on can cause layers to separate, forming a mica-like structure of separate layers, with significant loss of mechanical toughness.

As far as the aluminum, Boeing versus Airbus, here's what I have:

Boeing versus Airbus Competing Metal to Composite Focus

In comparison, Airbus has increased its use of advanced materials on its A350 to 60 percent (39 percent composite and 21 percent aluminum-lithium alloy). However, in contrast to Boeing, Airbus is using aluminum-lithium for most of the fuselage structure, restricting composites use in fuselage structure fabrication to the rear of the pressure bulkhead and the empennage/vertical tail structure. For Airbus, the primary consideration for this design choice is their belief that there will be less time out of service if aluminum-lithium is used as maintenance teams will be able to use standard repair procedures in an open hangar, while composite repair requires more controlled conditions.

Aluminum Alloy Development for the Airbus A380

The material distribution on an Airbus aircraft structure predominantly remains on aluminum based alloys. The example on the A380 super sized aircraft shows that 61% of the structure is made of aluminum alloys, 22% in composites, 10% in titanium and steel and 3% in fiber metal laminate. Nevertheless, the use of composite materials is continuously growing and the new A380 contains 22% of composite structures compared to 12% on the A340.

787 Dreamliner

Material breakout on 787
Composites - 50%
Aluminum - 20%
Titanium - 15%
Steel - 10%
Other - 5%

As far as a simple explanation of the difference between a composite and an alloy:

Types of Composite Materials

A composite material is a material made up of two or more materials that are combined in a way that allows the materials to stay distinct and identifiable. The purpose of composites is to allow the new material to have strengths from both materials, often times covering the original materials' weaknesses. Composites are different from alloys because alloys are combined in such a way that it is impossible to tell one particle, element, or substance from the other.

From this explanation it starts to become clear that the behaviors of composites are catalogued as they occur. This is not something that lends itself to computer simulation. Therefore, certification based on computer simulation, in this case, is not applicable.

Certification wasn't done by computer simulation. Modeling was done, but final certification was done with live testing. Both the A350 and the 787 had parts that will be/were tested to destruction, as well as tested in labs designed to mimic flight conditions. There is one complete wing, for example, that only exists to be broken. It's required to withstand up to 1.5 times the maximum possible load that the wing will see in normal flight conditions (basically if the plane falls straight down, in clear air turbulence, and loads the wing to 1.5 times the normal load, it will stay intact).

Boeing 787 wing break test:



Boeing has a lightning lab where they put the materials used on the 787 through repeated lightning strikes to test how they would react, as well as to test the lightning protection of the aircraft. The aircraft also went through several lightning strikes during flight testing (not intentional) and passed them all perfectly. There were initial problems with fasteners in the fuel tanks, but the simple change of putting the heads outside the tank where possible, and putting sealant on the ones that couldn't, fixed the problem.

reply to post by luxordelphi


Your sources regarding fuselage composition were for the original A350 which was cancelled because it was uncompetitive. It was largely an upgraded A330 with new engines, a new wing, and slightly more advanced materials such as an Al-Li fuselage. The A350 XWB which replaced it originally had composite panels mounted on a aluminium frame, but that was again ditched to composite panels mounted onto a composite frame.

The A350 XWB’s major fuselage sections are created by the assembly of four large panels each, which are joined with longitudinal riveted joints. One advantage of this approach is a better management of tolerances when the jetliner’s composite fuselage sections come together on the A350 XWB Final Assembly Line in Toulouse, France.

www.a350xwb.com...

The same website, which is the official website, shows 53% composite by weight.

reply to post by Zaphod58


I blame the translation of the instructional manual. You know....Lost in Translation. For example.

On Sears hair dryer:
Do not use while sleeping.

On a bag of Fritos:
You could be a winner! No purchase necessary. Details inside.

On a bar of Dial soap:
Directions: Use like regular soap.

On some Swanson frozen dinners:
Serving suggestions: Defrost.

Printed on the bottom of Tesco Tiramisu dessert:
Do not turn upside down.

On Marks and Spencer Bread Pudding:
Product will be hot after heating.

On packaging for a Rowenta iron:
Do not iron clothes on body.

On Boot's Children's Cough Medicine:
Do not drive a car or operate machinery after taking this medication.

On Nytol Sleep Aid:
Warning: May cause drowsiness.

On most brands of Christmas lights:
For indoor or outdoor use only.

On a Japanese food processor:
Not to be used for the other use.

On Sainsbury's peanuts:
Warning: Contains nuts.

On an American Airlines packet of nuts:
Instructions: open packet, eat nuts.

On a child's Superman costume:
Wearing of this garment does not enable you to fly.

On a Swedish chain saw:
Do not attempt to stop chain with your hands or genitals.

On a toboggan:
Beware: Sledge may develop high speed under certain snow conditions.

On a knife sharpener:
Caution: knives are sharp.

reply to post by C0bzz


Thankyou for that clarification. From the Airbus site:

Innovative Fuselage

lighter advanced metals are used in the A350 XWB's extra-wide fuselage

The A350 XWB's innovative carbon-fibre reinforced plastic fuselage plus aluminium-lithium and titanium alloy components result in lower fuel consumption and easier maintenance.

So not an alloy at all. In any event, not our fathers' alloy. I understand now why they say it's all composite.

TDawgRex
reply to post by Zaphod58

 

I blame the translation of the instructional manual. You know....Lost in Translation. For example.

On Sears hair dryer:
Do not use while sleeping.

On a bag of Fritos:
You could be a winner! No purchase necessary. Details inside.

On a bar of Dial soap:
Directions: Use like regular soap.

On some Swanson frozen dinners:
Serving suggestions: Defrost.

Printed on the bottom of Tesco Tiramisu dessert:
Do not turn upside down.

On Marks and Spencer Bread Pudding:
Product will be hot after heating.

On packaging for a Rowenta iron:
Do not iron clothes on body.

On Boot's Children's Cough Medicine:
Do not drive a car or operate machinery after taking this medication.

On Nytol Sleep Aid:
Warning: May cause drowsiness.

On most brands of Christmas lights:
For indoor or outdoor use only.

On a Japanese food processor:
Not to be used for the other use.

On Sainsbury's peanuts:
Warning: Contains nuts.

On an American Airlines packet of nuts:
Instructions: open packet, eat nuts.

On a child's Superman costume:
Wearing of this garment does not enable you to fly.

On a Swedish chain saw:
Do not attempt to stop chain with your hands or genitals.

On a toboggan:
Beware: Sledge may develop high speed under certain snow conditions.

On a knife sharpener:
Caution: knives are sharp.

The sad part is, they are all on there because someone has tried it before!