Mitsubishi unveils major changes to MRJ programme *drops carbonfibre for aluminium*, page 1

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Topic started on 9-9-2009 @ 04:18 AM by Harlequin

www.flightglobal.com...

Mitsubishi Aircraft has introduced a stretched variant to its MRJ regional jet family and unveiled extensive design changes, including using aluminium instead of carbonfibre composites for the aircraft's wings.

and

With the aluminium wings, the company moves away from its earlier aim of using significant amounts of composite materials for the airframe. The result is that the only remaining composite parts will be the empennage, horizontal tail and vertical tail, amounting to 10-15% of the total airframe

i wonder how much of this is related to boeings disasterous experiences with the 787?

[edit on 9/9/09 by Harlequin]

reply posted on 9-9-2009 @ 06:02 AM by RichardPrice

Originally posted by Harlequin
www.flightglobal.com...

Mitsubishi Aircraft has introduced a stretched variant to its MRJ regional jet family and unveiled extensive design changes, including using aluminium instead of carbonfibre composites for the aircraft's wings.

i wonder how much of this is related to boeings disasterous experiences with the 787?

[edit on 9/9/09 by Harlequin]

Its worrying that the major contractor that is supplying Boeing with composite wings for the 787 has switched to non-composite for its own aircraft - Mitsubishi should have excellent experience with composite wings and parts these days.

I wonder whats up.

reply posted on 9-9-2009 @ 12:42 PM by kilcoo316

Originally posted by RichardPrice
I wonder whats up.

CF is not close to achieving what the PR people state.

Tons overweight compared to a modern metallic wing.

Airbus know it, Boeing know it, Bombardier know it, Embraer know it and so do Mitsubishi...

The former 3 know it from what they've done to date, but have proceeded or are proceeding anyway (although one of them *may* be thinking about a reversion) Embraer have refused to commit to it.

Mitsubishi so far are the only crowd to listen to the engineers and allow them to say "no, CF is not ready for the bigtime" and it is listened to above the cries of the PR bunch who say composites are now necessary to sell planes.

Its a f**king ridiculous state of affairs to be honest.

reply posted on 9-9-2009 @ 01:07 PM by RussianScientists

reply to post by kilcoo316

Sorry kilcoo 316, but carbon fiber is a lot lighter and stronger than aluminum.

The problem with carbon fiber for wings is stress cracks from the engines and lightening strikes. The delamination of the interwoven carbon fiber takes considerably longer to repair and to inspect.

Lightening strikes on the carbon fiber wings blows holes into the wings, unlike aluminum wings which don't need repair from lightening strikes because the electrical shock is spread out over the aluminum skin.

Stress cracks and lightening strikes on the wings take a lot longer to repair and inspect with NDI (Non-Destructive Inspection) when its carbon fiber than when its aluminum to repair; which means a lot less flight time when a plane lands or takes off in a lightening storm and gets struck by lightening.

reply posted on 9-9-2009 @ 02:12 PM by kilcoo316

Originally posted by RussianScientists
Sorry kilcoo 316, but carbon fiber is a lot lighter and stronger than aluminum.

Not when you need nearly isotropic properties it is not. Nor when your design allowables are absolute rubbish because manufacturing tolerances are absolute rubbish.

As an academic exersize, composites are brilliant. In the hard light of day, when safety factors built on manufacturing repeatability, FAA confidence and LVI damage are added... they are not.

As well as that, there are the maintenance issues you mention.

BTW - I'm not basing my arguments on theories, I'm basing them on numbers I'm seeing, others I'm getting first hand, and yet more I'm getting second hand from people working on the things (ALL of them).

Right now, there is not a commerical aircraft manufacturer in the world that could not build a lighter metallic wing (for civil aircraft) compared to their best composite one.

[edit on 9/9/09 by kilcoo316]

reply posted on 10-9-2009 @ 03:44 AM by Harlequin

i would like to add one thing;

the wing box stringers were showing failure at 120% load > to actually be certified they need to get to 150% >> 120% isn`t even limit load and could and does happen during regular flight!

were now into september with no real progress on the issue - with the fix being aluminium or titanim , i think boeing themselves are realising that CF is not the way to go

reply posted on 10-9-2009 @ 06:10 AM by RichardPrice

Originally posted by Harlequin
the wing box stringers were showing failure at 120% load > to actually be certified they need to get to 150% >> 120% isn`t even limit load and could and does happen during regular flight!

Uhm, by definition 100% is the limit load, and 150% is the ultimate load. An aircraft should never experience > 100% in its life, and most aircraft never exceed 80%.

reply posted on 10-9-2009 @ 08:06 AM by Harlequin

reply to post by RichardPrice

my aplogise for adding a word there - it failed at 120% way down on the FAA certification of 150%

seattletimes.nwsource.com...

reply posted on 11-9-2009 @ 02:03 PM by HatTrick

As an aside - Mitsubishi makes one of my favorite planes - the MU-2.

I'd like to see that go into production again.

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