The entire wing program was executed under a rapid prototyping process. And while there was concern about void content (air bubbles or empty spaces), Chu acknowledges that worry is present whenever composite materials are used. “While some out-of-autoclave material systems can have higher void contents, the wing is sized to material properties that account for void content. We did not run a full characterization of void content, but photomicrographs showed void content consistent with the aerospace standard of 1 percent or less,” he says.

Boeing hopes the Phantom Eye will usher in a new era of unmanned airborne surveillance with its ability to stay aloft for four days, eventually 10, at 65,000 feet. “While 16 months might seem like a long time in human terms, it represents a short time span to design and fabricate a wing, which is one of the largest structures ever created using OOA materials. We could not find anyone who says they have built a larger structure,” says Chu.