Click here to read our main story: Secret New UAS Shows Stealth, Efficiency Advances.

In December 2011, Iran proudly displayed on state television a stealthy U.S. unmanned aircraft it claimed it had downed while conducting reconnaissance overflights. The trophy was a Lockheed Martin RQ-170 Sentinel, an aircraft publicly acknowledged by the U.S. Air Force two years earlier.

Even before, the existence of the RQ-170 had been a poorly kept secret. The unmanned aerial system (UAS) was operating out of Afghanistan and flying over Pakistan and Iran for an undetermined period before it was photographed at Kandahar AB, Afghanistan, in 2008. Later, in 2011, it was involved in the raid in which Osama bin Laden was killed (AW&ST Dec. 12, 2011, p. 19).

The Pentagon played down that embarrassing loss of the UAS. One reason may now be clear. Defense and intelligence sources say the Sentinel was the result of a quick-reaction project designed for specific missions, and not with an eye toward an enduring presence in the fleet. That position was reserved for a new, secret UAS—Northrop Grumman’s stealthy RQ-180.

To fully understand this new UAS, one must view it in the context of the larger “family of systems” the Air Force envisions to include long-range strike and intelligence, surveillance and reconnaissance (ISR) platforms. A 2010 presentation by the Air Force’s director of operational requirements at the time, Maj. Gen. David Scott, made that connection.

Emergence of the RQ-180 allowed the Air Force to reduce requirements for what was once called the Next-Generation Bomber (NGB), a program terminated in 2009 because of its high cost. The follow-on Long-Range Strike Bomber (LRS-B) is a less-expensive option that will rely on interoperability with the RQ-180 and other systems in the family.

In 2008, when Northrop is believed to have won the contract to develop the stealthy penetrating UAS, the Air Force was facing criticism from then-Defense Secretary Robert Gates that it was falling short in supporting ISR requirements for the wars in Iraq and Afghanistan. But behind the scenes, defense planners and the intelligence community were worried about a lack of information on some well-defended locations such as North Korea and Iran.

This was also in the wake of the Air Force and Navy’s divorce over the effort to jointly develop a single stealthy UAS capable of ISR collection and striking from land or sea. The Joint Unmanned Combat Air Systems (J-UCAS) program was terminated late in 2005. The Navy, in search of carrier-based ISR, proceeded with the X-47B UCAS demonstration and now plans to buy a follow-on called the Unmanned Carrier-Launched Airborne Surveillance and Strike (Uclass) system. The Air Force directed its funding and technology to a classified program, likely the RQ-180.

Despite heavy pressure on defense spending, the RQ-180 is moving forward. Cuts to classified budgets are “relatively proportional” to those for white-world programs, says acting Air Force Secretary Eric Fanning. “This is the first time I’ve been in the Air Force where we’ve taken a really close look on the classified side to make sure the investments are closely aligned. We are not missing opportunities there to take cuts on the unclassified side...There were some shifts, [but] nothing overly major at this point.”

Because of war requirements in Iraq and Afghanistan, where coalition air forces could operate with little threat from the ground, the Air Force had poured funding into ISR collectors without stealthy characteristics such as the Beechcraft King Air-based MC‑12W Project Liberty and Blue Devil 1 intel platforms.

“For a decade now we have built the most incredible permissive ISR capacity and capability that anybody has ever seen,” Air Combat Command’s chief, Gen. Michael Hostage, said in September. “We are being forced to build a capacity [with the Reaper] I know I can’t sustain, and I know I don’t need based on the national strategy,” which calls for operating in heavily defended airspace, as well. He says Pentagon officials are sorting through what is needed to handle the more challenging threats. “We are talking about the entire ISR construct—how much in permissive, how much in contested and how much in denied” is needed.

Not since the Mach 3 SR-71 program ended in 1998 has the Pentagon been able to overfly targets in hostile airspace to collect intelligence. The proliferation of longer-range and integrated air-defense systems, coupled with its high operating cost, banished the Blackbird to museums. And in 1999, the Pentagon terminated the RQ-3 DarkStar UAS, a potential successor under development by Lockheed Martin and Boeing as a stealthy adjunct to Northrop Grumman’s RQ-4 Global Hawk, after it encountered flight-stability problems. These developments left unanswered a Pentagon Joint Requirements Oversight Council mission-need statement for an aircraft capable of operating in defended airspace for long periods.

Though satellites are capable of peering behind borders, they lack the persistence and flexibility of aircraft. Satellites are limited by slant ranges, a problem that aircraft can mitigate by altering their flight paths. Also, adversaries can predict when a spacecraft will fly overhead and adjust their operations accordingly.

High-speed platforms continue to be evaluated, such as Lockheed Martin’s hypersonic SR-72 concept (AW&ST Nov. 4, p. 18), but planners leery of acquisition foul-ups and higher-risk technology opted for stealth in order to field a system as soon as 2015.

The expectation that the RQ-180 will be fielded soon has helped to cement support for the Air Force’s abrupt change of heart on the Northrop Grumman Global Hawk high-altitude, long-endurance UAS—once the centerpiece for the service’s ISR development plans. The Block 30 Global Hawk was eyed as a replacement for the manned U-2 for stand-off ISR collection, in which aircraft just loiter outside hostile airspace peering into enemy territory to gather images and signals. Though not able to fly as high (50,000-60,000 ft. versus the U-2’s 70,000 ft.-plus), the Global Hawk could loiter for a day or longer and not expose pilots to the health hazards of prolonged missions at extreme altitudes, a problem during long flights supporting operations over Afghanistan.

Despite deeming Global Hawk critical to national security in 2011, the Air Force less than a year later proposed terminating the Block 30 version, citing the high operating cost it had once defended. The Air Force also cited lackluster performance of the Block 30’s electro-optical and radar-sensor suite, despite earlier assertions that these issues were manageable (AW&ST June 13, 2011, p. 35).

Now the more advanced, stealthy RQ-180, capable of penetrating an adversary’s airspace, has superseded the Global Hawk. The Air Force is now standing behind the U-2, with some cockpit and sensor upgrades, as its workhorse stand-off intelligence collector, with the RQ-180 poised to take on the penetrating mission.

In a high-level roles-and-missions trade, the Air Force assumed authority for developing a stealthier, longer-range, land-based UAS capable of penetrating the most defended airspace, guarded by advanced surface-to-air missiles and jammers. Meanwhile, the Navy, is mired in a debate over how stealthy to make its Uclass air vehicle when a high degree of stealth would push costs higher. With the Air Force operating the RQ-180, the Navy would have the option to cut its costs on Uclass.

Perhaps indicative of the debate, the Navy has been coy on the requirements and design specifications for Uclass. The Office of the Secretary of Defense and the Joint Staff are pushing for Uclass to operate only in “contested” airspace—the Pentagon’s word for areas that are defended but not with the most advanced weapons systems. But Navy officials are hoping for a more survivable—though more expensive—design capable of operating over the best-defended areas or “denied” airspace, in Pentagon parlance.
Furthermore, the Air Force plans to retain its MQ-1 Predator and MQ-9 Reaper UAS for operation in uncontested or lightly contested airspace. The so-called MQ-X, which was to be a Reaper follow-on, disappeared from Air Force long-range planning in 2012, another sign its UAS planning was refocusing around the RQ-180.

If the RQ-180 can prove itself operationally, the Air Force will have addressed its need for a high-altitude penetrator. The next big challenge in rebalancing the service’s ISR fleet will be to define the future of the Predator and Reaper and their potential successors.

See an illustrated heritage of stealthy UAS here.