An April 2001 collision between a U.S. Navy EP-3E signals intelligence aircraft and a Chinese fighter revived interest in a high-altitude, long-endurance UAV. Various designs were considered, including a V-tailed Lockheed Martin concept called Distant Star (or Penetrating High Altitude Endurance), but great things were expected (at the time) from high-resolution, space-based radar. Consequently, expectations were scaled back, and in late 2001 or early 2002 Lockheed Martin was awarded a contract for a simpler, medium-altitude tactical stealth UAV, which became the RQ-170 Sentinel.
Another late-1990s development that has been significant in terms of current programs was the emergence of the unmanned combat air vehicle (UCAV) concept. In 1999, Boeing won a contract from the Defense Advanced Research Projects Agency (Darpa) to build two X-45A UCAV demonstrators, which were tested in 2002-06.
In the heady transformational days of the Donald Rumsfeld-led Pentagon, the UCAV gathered momentum quickly. By 2002, the Navy was looking at an operational vehicle. By 2003, the UCAV project had become Darpa's Joint Unmanned Combat Air System (J-UCAS) and the first wing was expected in Air Force service in 2010. However, powerful forces were threatening to blow J-UCAS apart.
The Air Force wanted a bigger vehicle than an aircraft carrier could accommodate, on the grounds that persistence was a key advantage of the UCAV over a piloted aircraft. Northrop Grumman responded with successively larger versions of its X-47C design, ending up with two engines and a 172-ft. wingspan.
A further change took place in 2003, as the Air Force defined its J-UCAS as a “Global Strike Enabler.” The service built the UCAV's role around its ability to “go deep and persist,” flying into heavily defended airspace and remaining there long enough for manned strike aircraft to fly in, complete their missions and leave. This would be made possible by the UCAV's stealth, range and endurance—the service was looking for 2-hr. endurance combined with a 1,000-nm unrefueled radius.
Because it was difficult to carry enough kinetic weapons for 2 hr. of defense suppression, the Air Force was particularly interested in airborne electronic attack (AEA) and information warfare systems. The stealthy UCAV would be able to approach closer to an emitter than a manned aircraft and jam it effectively with less power. One Air Force officer noted at the time that the service was “examining various ways to use [information warfare] attack to cause an integrated air defense system to implode on itself.” Information warfare, he added, was “the great equalizer against integrated threats, because it forces them to operate autonomously.” Weapons would include up to eight Small Diameter Bombs (SDB).
Along with ISR requirements and the UCAV project, a third influence on what is happening today was the Air Force Research Laboratory's Sensor Craft program, started in the late 1990s. Sensor Craft took on the main challenge of Quartz—combining efficiency with stealth. Its main thrusts were the maintenance of natural laminar flow control on swept wings, structurally integrated sensors and unusual configurations, including joined wings. At Northrop Grumman, Sensor Craft work blended with its in-house studies of “cranked kite” configurations that were stealthy and offered “sailplane-like” efficiency, in one engineer's words. Lockheed Martin, meanwhile, unveiled its Polecat demonstrator in the summer of 2006, aimed at similar goals.
Also in 2006, the Quadrennial Defense Review terminated J-UCAS. It was openly reported at the time that while the Navy continued with its carrier-based demonstrator (the Northrop Grumman X-47B), Air Force J-UCAS money was going to a classified program. At the time, the RQ-170 was just starting flight tests, and two batches—totaling fewer than 20 aircraft—were ordered. It would serve as a stopgap until the bigger aircraft was ready.
The classified program had a slow start because it competed with Space Radar, which enjoyed high-level support. However, with personnel changes at the Pentagon, the Air Force concept for a long-range, unmanned, combat ISR/AEA aircraft to suppress, destroy and degrade defenses became reality.
It now appears that the large contract awarded to Northrop Grumman in early 2008, which seemed at the time to cover a demonstrator for the Next Generation Bomber (NGB), was a development contract for the armed ISR aircraft. It is believed to be a single-engine aircraft with a wingspan similar to a Global Hawk, and (given Northrop Grumman's enthusiasm for the cranked-kite configuration) it most likely resembles the X-47B, but with larger, more slender outer wings. It has radar, electronic surveillance systems and active electronic warfare equipment and, quite possibly, a weapon bay for SDBs and Miniature Air Launched Decoy-Jammer (MALD-J) expendable jamming vehicles. It may also be equipped to act as a communications gateway for other aircraft, using either satcoms or high-frequency radio.