BEIJING—Indonesia will pay $10 million to cover 20% of the cost of concept definition of South Korea’s proposed KF-X fighter, and will send 30 researchers to work on the project. Korea Aerospace Industries and missile and electronics systems maker LIG Nex1 are the preferred South Korean candidates for the program, while Indonesian Aerospace will also participate, according to the South Korean Defense Acquisition Program Administration.

Adding to the many decisions to be made in designing a commercial aircraft, the choice of material is becoming more complicated as more choices become available. Yet the issue is as decisive as almost any other, since overly costly construction will burden an aircraft with a competitive disadvantage throughout its life, while an airliner that is cheap but heavy will burn too much fuel for decades ahead—decades in which fuel prices could rise far beyond expectations.

A facial expression hints at the Chinese aerospace executive's concern. “Yes, it is indeed a big challenge,” he says, sounding serious. As he stops to sip his coffee, he begins to look a shade more serious. Maybe the challenge is just too big.