Agree with a lot of it but it is not all doom and gloom death and destruction with CFRP.
Fire tests etc are conducted on panels which could be in normal (in service outside of the bounds of a crash gone bad), lightening tests are also conducted on structions which have the possibility of a lightening strike, composites have been flying for long enough for people to know what to do and there is enough comman sence around to try and isolate fuel bladders and tanks from bolts which may have some lightening strike on them but yes all these things are probably yet to be fully tested.
The epoxies used on these types of structures may not turn to liquid at 220C (temperature alone by the way as you know is not the only key thing) but yes composite structures do tend to lose structural integrity beyond the Tg and people are usually very careful about all this.
If the CFRP is in a “Hot” area, they use BMI. That can stand 450 deg F. Main structures are not BMI.
There is no fuel bladder in a large commercial Jet. Fuel is in direct contact with the skins and spars and sealing ribs. As I said, you’d better pray that all the bolt tails have been PERFECTLY walnut-whipped. The testing is ongoing as the damn things are being built, that’s why all 7 of the A400’s pre-production batch are all fundamentally different. And EIS is different from set 7. And there is already a mountain of Change notes on the EIS. 787 is turning out to be the Nightmareliner, with spectacularly incorrect designs, choice of fasteners etc.
CFRP is cooked in an autoclave at 220F for about 6 hours. OK, the resin changes it’s structure slightly after the cook, may even get a few 10’s of degrees out of it. Take a look at the Airbus that caught fire on the runway a few years back, the empennage (CFRP) is a black soot pile.
The lightning tests on A400, A350 and 787 are not looking too good at all. The large horizontal surface peppered with metal bolt tops is a serious problem. The h-stabs that have been carbon in the past contained no fuel. The lightning strikes they received left a concerning amount of surface burn.
Large and small military platforms have used CFRP for wings and main structures but they used a bond as the primary join and backed it up with fasteners. This is not good enough for large floppy airliner wings supporting pax. Military folk have a “Mummy!” handle and a parachute. The fighters in particular have a very stiff wing, usually 5 spars in it.
“Careful” is an understatement. But the pressure on industry to make a platform out of CFRP is immense. Pressure which is perhaps forcing the race.
The things I mentioned have not been solved, despite the best brains in the industry working on them. They will be solved, at massive weight and cosst penalties. The pax want’s flights to NY for £99 etc. Plastic airliners are not going to assist in this permanent price war.
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