I got the impression from the article his biggest concern was aluminium frames, rather than the panels......
|Quoting SEPilot (Reply 7):|
I see the advent of CFRP airliners as being almost as big a jump as was the jet engine, and the panel approach (especially over aluminum frames) as being a turboprop. The issue is maintenance rather than weight.
To be honest, I'm struggling to get my head properly around this maintenance issue.
Firstly, I have my suspicions that we're focussing (yet again) on a small part of the subject, and extrapolating it to the whole aircraft.
Over the life of an aircraft, just what percentage of TOTAL maintenance (fuselage skin, other structures, engines, landing gear, wings, tails, control surfaces, electrics, hydraulics, other mechanical systems, electronics/avionics, IFE, etc etc) is attributable to the connection between the frames and the shell?
If it were a submarine, we'd be talking fractions of a percent.
I certainly have no idea for an aircraft, (and I'm nervous that I'm comparing "nautical" engineering to "aeronautical" engineering).
But it begs the question.
Secondly, Airbus are specifying maintenance schedules that match or beat the 787.
I don't subscribe for one second to the notion that this is being done purely as a "me too" exercise, with NO engineering back-up. CFRP/Al structures have been around a long time, as has the issue of their corrosion.
Also, the A380 has them, the 787
has them, and the A350 has them. Other aircraft have them.
Maybe my job makes me somewhat blase about maintenance/corrosion - through the life of a nuclear sub, it has a monumental impact on the product engineering. (and again I'm nervous that I'm comparing "nautical" engineering to "aeronautical" engineering).
But my limited
knowledge leaves me mystified as to why we believe it's physically impossible to engineer a "40 year" aircraft from CFRP and Al.
Might not be easy, and there might be other trade-offs that are required, in other product characteristics.
OTOH, it's obviously something the industry's nervous about.
It's also obvious that it's far easier to sell the concept of "all-CFRP" barrels, and despite the above comments, I would find it easier to accept the arguments for a "similar material" structure, rather than a "dissimilar material structure.
(I personally have my reservations about exactly why S-UH is making his comments, but that's a different matter..)
|Quoting SEPilot (Reply 12):|
I agree with SUH that CFRP frames shouldn't be that difficult to do; I can see no reason why Airbus doesn't use them.
This thought too has occurred to me (surprise surprise). It has to be far easier to develop CFRP frames than the whole barrels.
The only sensible thought that comes to mind is that both Boeing and Airbus have said that, for the CFRP wings, Al ribs make more sense for the highly loaded ribs, and therefore, by extension, all of them.
(An argument in which I have to defer to the knowledge of the builders - given the "hype" over CFRP on this forum, the comments are surprising)
Is this a function of the A350's frames seeing "higher loads" and therefore Al is more suitable, as with the wings?
We (on A-net) seem to have written this off as a given.
What if it doesn't?
Re-reading, all I've done is posed lots of questions.
I guess the biggest question I have is over the cast-iron certainty that we seem to have that the argument is already won...
Is it, I wonder?......