So why give them weapons bays if they're never going to be used? As a technology demonstrator, the X-47B was designed to mimic the flight characteristics of an armed, unmanned combat jet. And the Navy does indeed plan to create an unmanned, carrier-capable combat jet. It will be developed through a program called UCLASS, or the Unmanned Carrier Launched Airborne Surveillance and Strike system (not to be confused with UCAS, which is the X-47B technology demonstration program). The ordering of the words in that title are no mistake; the Navy wants a stealthy, long-range jet that can launch from carriers primarily for use as an intelligence-gathering and surveillance tool. But the Navy also wants something that can penetrate enemy air defenses and deliver precise strikes (say, on a nuclear facility or a missile launch site) in situations in which sending manned strike aircraft might result in pilot casualties. It's the X-47B's job to prove out the technologies that will lead to such an aircraft (the Navy hopes to have that future UCLASS aircraft operational by 2020). The X-47B is designed to be as much like a future combat aircraft as possible, right down to the inclusion of weapons bays in its design. But under the Navy's current plans it will never use them.