tjh8402 wrote:While I get what you're saying, I do think composites are a poor example, as commercial builders are concerned with the economies of scale and mass production, whereas high end military products can be boutique buys and usually involve smaller pieces. It's much less of a production challenge to build composite empennages for F-15s than it is for planes the size of a 787, much less the 777 (recall that supposedly one of Boeings challenges for the 777x was designing an autoclave large enough to make the wings).
I'd also point out that military aircraft made primarily of composite structures are still relatively new. From what I can tell, the first mass produced (so no F117s or F22s) military jets to be made primarily of composites were 4.5 generation planes like the Euro canard twins, and those only entered service this century, even if their first flights were a long time before. As best I can tell, the F-35 is actually the most ordered composite military aircraft and is currently the third most produced behind the Typhoon and F-22 Raptor.
There's also a huge difference between mastering something groundbreaking like composite construction and a mechanism and action that's been in regular use since the second world war.
Perhaps appropriate to this discussion (or perhaps not), but Boeing did composite, folding replacement wings for 200 A-6 Intruders in 1985.
http://www.globalsecurity.org/military/ ... grades.htm says:
The Boeing Company had begun to design a new wing under a Navy contract that was awarded in 1985. With a carbon fiber-epoxy resin torsion box, light alloy control surfaces, and some titanium components, the new wing was much lighter and designed for four times the fatigue life of the existing wing. The composite wing was retrofitted to about 200 A-6E aircraft, which significantly increased the aircraft's capability, safety, and operational life. In addition to becoming a retrofit for the A-6E fleet, the wing was also intended for a new, advanced version of the A-6 to be known as the A-6F. The A-6F was later canceled in the prototype stage when the Navy decided to replace the A-6 fleet with the stealth A-12 aircraft.
They also did the composite wings for the F-22.
I agree the military space is different, but it shows that the basic tech is in place.
mjoelnir wrote:The folding wingtip will come with the 777-8/9 and there is no reason it should not work. If they do not fold on arrival the frame will need an A380 gate or remote stand. I assume the frame will be able to fly with the tips folded. If the failure rate is similar to inoperable flaps it should be good.
I think there is no reason to worry that Boeing will not solve all technical problems regarding such a system.
Assume, you say? Again, my earlier reference from Boeing's VP for the 77X says a wingtip failure will ground the aircraft.