787 - Composite Development route

[NWSRG]

With Boeing having stated that the 787 will carry additional composite structure in some areas to offset the fears of some airlines about 'ramp rash', will Boeing reduce the additional structure over time?

Presumably, the aircraft will be over-engineered, composite-wise, as it is a 'first'. Will Boeing review the 787 structure during the aircraft lifetime, with a view to stripping away the excess material as knowledge of composite in service improves?

I have seen some information suggesting that the 787 fuselage will have virtually no weight benefit over a similar sized aluminium fuselage initially...maybe the 797 (whatever that will be) will be the first aircraft to fully benefit from composites.

[IHL]

I don't think that there ever has been an airframe that got lighter over time. I severly doubt that future [ serial number wise] 787 will get lighter.

[Wander]

We had those nice chaps from Seattle gives us lowly charter boys a brief on the 787 a while ago. They are pushing the strength of the composities in a major way; video of people hitting a section with a hammer and comparing it with aluminium!
They say it'll be 20% lighter than an equivalent traditional a/c. Hence the extended ranges they are quoting; Australia from LGW in one go! They have included some items to help assess damage around the cargo loading bays and doors. Essentially they're electrical circuits embedded in the fibre. How hard the a/c is smacked by, say, a truck dictates how much of the circuit is broken and consequently what level of warning is received in the cockpit.
How on earth you repair that sort of stuff i don't know! I'm not at all sure how you assess fatigue on carbon fibre, just ask Pete Goss!!

[NWSRG]

I know one of the designers who worked on the A380 wing...and he was telling me that the first task after engineering the initial design would be to review the whole wing to remove weight from subsequent units.

Would the same not happen with a fuselage? I still wonder if Boeing might make a number of step changes to the composite structure over time, as they gain knowledge (and operator 'comfort') with the technology...

[barit1]

A famous engineering manager of 50 years ago admonished his troops "If it works right the first time, it must be overweight. Go back and remove weight until it breaks!"

[jet_fumes_junkie]

what NWSRG refers to may be some counterarguments from a-bus, they're not happy with so much composites (45%, 35% more than 777), an "untested" material being used....
boeing claims composites have 30% higher stw ratio than aluminum in a lab, translating into 15 in real life.
weight wise, they say it's 10,000 lbs less than had al been used (take that haneda landing fees:D no wonder ana was launch customer).
the biggest thing is supposed to be corrosion - nonexistent - that is supposed to save 30 percent on maintenanace over lifetime, really starting to make a diff after 12 years, especially around galleys and lavs.

and it was the composites that enabled 6,000 ft cabin instead of 8, also 30% larger windons (11x19 inches)

still, it's gonna be a cattle-hauler in economy !:ok:

[wowpeter]

Composite will be much superior then Al because it does not fatigue. So that's why maintanence interval of the 787 will be much longer then comparable Al aircraft. I think from what I read from Flight International, Boeing claims that 787 will have 30% less maintanence check then a Al aircraft... Also, I don't think Boeing will over engineer the aircraft because airlines might worry about the use of this relatively new materials, if they over engineer their aircraft it will make the 787 not competitive over A350...
What Boeing is doing though, is that they are going around to different airlines and doing many demonstration to prove to the airlines that composite is tougher then Al... They are also showing airlines quick repairing methods is possible... But one of the things to be work out will be moisture within the composite structure... especially on honeycomb composite structure (on the tail)... as you can see from the vertical stabililizer falling out from the A300... once water manage to get into the composite stucture, it will soak it and weaken it very quickly... but I am sure smart engineers at Boeing will work that out for sure :O)

[MiG82]

CFRP does get fatigue cracking. If you have heard that it doesn't fatigue then it must be only under certain circumstances.