Aviation Week & Space Technology, Aug. 29, 2011, p. 46

Big Wing

Evidence suggests Northrop Grumman won classified contract to develop new stealthy UAV

BY Bill Sweetman Washington

Classified programs now under way may lead to one of the most capable and expensive airborne intelligence, surveillance and reconnaissance (ISR) and airborne electronic attack (AEA) systems available to the U.S. Air Force in the 2020s. Reports from defense and industry sources, and careful analysis of USAF presentations and other documents, indicate that there is a major "black" ISR and AEA initiative going forward under special access program security rules.

The program was originally reported in early 2008, after financial reports revealed that Northrop Grumman had been awarded a large classified aircraft development contract. At the time, this was thought to be a demonstrator for the Next-Generation Bomber (now known as the Long-Range Strike Platform, or LRSP), but more recent information suggests that the contract is for a large, operational ISR UAV with an unprecedented combination of extreme low observables (ELO) and aerodynamic efficiency.

The Northrop Grumman aircraft is close to its first flight, if indeed that event has not already taken place. Most likely, flight testing is being conducted from a newly built hangar complex at Detachment 3 of the Air Force Flight Test Center at Groom Lake, Nev., and popularly known as Area 51.

To some extent, the program has been hidden in plain sight. Two important Air Force strategic activities—the service's unmanned systems flight plan, issued in 2009, and more recent work on a family of systems for long-range strike, or to deal with anti-access/area denial (A2/AD) threats—have pointed to the need for the aircraft's capabilities. A February 2009 paper by Col. Eric Mathewson, director of the Air Force's Unmanned Aircraft System (UAS) Task Force, refers to the project as MQ-L/O.  

In late 2005, Northrop Grumman proposed a long-range unmanned combat air vehicle much bigger than the X-47B, with a large weapons load. Credit: Northrop Grumman

The UAS road map uses a different name but identifies a relatively near-term system that corresponds to the Northrop Grumman aircraft. The MQ-La ("MQ" for multi-role unmanned, "L" for large and "a" indicating that it is the first of three evolutionary steps) is aimed at "urgent Cocom [component commander] needs" and will have radar sensors—synthetic aperture radar (SAR) and ground moving-target indication (GMTI). The system will "complement the Global Hawk," the report says, and the road map shows it operating alongside Global Hawk.

A 2009 paper by the Center for Strategic and Budgetary Affairs calls for development of a stealthy tactical UAV, "operating in the medium-altitude (15,000-40,000 ft.) regime to accomplish a broad set of missions, from full-motion video surveillance to direct action," and a stealthy regional UAV with a 48-hr. endurance, operating above 60,000 ft.

An October 2010 briefing by USAF Maj. Gen. David Scott, focused on A2/AD and the long-range strike family of systems, referred to two "enabling" capabilities that support all three weapons in the A2/AD battle—the LRSP; existing, new and improved standoff missiles; and a conventional prompt global strike (CPGS) capability. These enablers are "penetrating stand-in airborne electronic attack" (P-AEA) and penetrating ISR.

Since then, Air Force officers have repeatedly referred to these "enablers" in the context of the new bomber, making the point that the use of AEA and ISR assets is key to meeting cost targets for LRSP. "Stand-in" AEA—the use of a stealthy platform to operate close to threat radars, making it possible to blind powerful systems with less power—greatly increases the survivability of a bomber, which will be ELO but will be large and subsonic. Penetrating ISR is essential to standoff missiles and CPGS but also reduces the bomber's sensor requirements by taking on the task of wide-area search with SAR/GMTI.

These missions do not require Global Hawk-like endurance, but the concept of operations is "first in, last out" to cover the attacking force, which calls for a high degree of survivability. Tactically, the Lockheed Martin F-22 could provide this kind of support, but long-range missions—in the Western Pacific, for example—would require either carrier-based support from a platform such as the Navy Unmanned Combat Air System or MQ-L/O.

The Air Force, however, has no program of record for a stealthy UAV, with no visible budget lines for technology demonstration or development. The larger ISR vehicle—rather than a bomber demonstrator—is believed to be the focus of the Northrop Grumman program reported in 2008.

When the Joint Unmanned Combat Aircraft System (J-UCAS) was terminated in the fiscal 2007 budget, it was reported that Air Force funds were transferred into a classified program. During 2007, Northrop Grumman leaders hinted that the company expected to win a major restricted program. A financial report in early 2008 then disclosed a $2 billion surge in backlog at the company's Integrated Systems division.

Since that time, sources in Washington and elsewhere have reported that the company did win a program for a large stealthy platform, and that the program survived the budget cuts announced in April 2009. Also in 2009, a large new hangar was completed at Groom Lake, with 170-ft.-wide doors.

Technologically, the classified UAV may draw on work that was originally linked to the Air Force Research Laboratory's SensorCraft project, aimed at creating a stealthy high-altitude vehicle with extreme endurance and very large radio-frequency apertures embedded into its wings. One Northrop Grumman project under SensorCraft was HiLDA (High Lift-to-Drag Active), a stealth-compatible flying-wing shape that explored the degree of natural laminar flow control that could be attained with such a configuration.  

Located at the Air Force's secure flight-test facility at Groom Lake, Nev., this hangar was probably built to house an emerging classified program. Construction started in 2007. Credit: GeoEye/Google

The new craft, however, is not as large as the nearly 200-ft.-span SensorCraft and does not use its technologically challenging integrated arrays. Instead, the stress appears to be on ELO and aerodynamic efficiency with potential for later upgrades.

Northrop Grumman and J-UCAS documents have suggested that flying-wing shapes, with no surfaces even close to the vertical, can have inherently better LO characteristics than more conventional aircraft, particularly from all aspects and over a wide frequency band. (U.S. reliance on stealth technology has led to a resurgence of work on VHF early warning radars, which can negate some LO technologies, in Russia and China.) It is also possible to apply deep-section radar absorbent structure (RAS) around the entire perimeter of the vehicle.

Another possibility is a version of the "cranked-kite" configuration used on the X-47B UCAS-D. Northrop Grumman engineers have pointed out that the X-47 design family is scalable and adaptable to meet varying requirements, from the pure-diamond X-47A Pegasus (with no outer wings) to a 172-ft.-span X-47C projected in 2005, which would have been powered by modified General Electric CF34s.

Milestones in the development of ELO—representing a clear improvement in radar cross section (RCS) over systems such as the Lockheed Martin F-117, F-22 and F-35—include the late-1990s testing of the Boeing Bird of Prey prototype. More recently, it was reported that Boeing had "a more aggressive program of investments in advanced stealth technology over the last several years than Lockheed Martin" (AW&ST July 7, 2003, p. 20). Northrop Grumman's acquisition of Scaled Composites and the return of B-2 stealth guru John Cashen as a consultant show moves in the same direction.

There are indications that achievable RCS levels have been reduced in recent years. RCS test facilities across the U.S. have been upgraded since the F-22 and Northrop Grumman B-2 were designed: the range at Holloman AFB, N.M., was reequipped to handle bistatic measurements; and a sophisticated airborne RCS measurement system based on a modified 737, designated NT-43A, was delivered in 2001 and remains in use.

One paper—co-authored by a principal in DenMar Inc., the company founded by Stealth pioneer Denys Overholser—refers to the development of a body with an RCS of -70 db per sq. meter, one-thousandth of the -40 db associated with the Lockheed Martin Joint Strike Fighter (JSF).

Computational fluid dynamics—in its infancy when the B-2 was designed—will permit new stealth aircraft to achieve "sailplane-like" efficiency, according to sources familiar with Northrop Grumman technology. The management of complex three-dimensional flows is the key to achieving laminar flow over much of the wing, and designing efficient exhaust and inlet systems that block MQ-L/O is also apparently capable of high-altitude flight—which has been a challenge for flying-wing aircraft, for reasons of controllability. This gives its sensors and jammers a large coverage area, particularly in rugged terrain where shadow areas are a problem for low-flying aircraft, and improves survivability because high-altitude aircraft are less likely to be detected visually by fighter pilots.

The Air Force, meanwhile, continues to deploy the Lockheed Martin RQ-170 Sentinel, nicknamed "the beast of Kandahar" after it was sighted at the Afghanistan base in 2009. The RQ-170 has also been credited with providing overhead imagery of Operation Neptune Spear, the May 1 action in which U.S. special forces killed Osama Bin Laden.

More recent photographs confirm that the RQ-170 is a relatively small vehicle, similar in size to the late-1990s RQ-3A DarkStar. The electro-optical/infrared package—possibly related to Lockheed Martin's Alert, a UAV sensor system that uses components of the JSF's Electro-Optical Targeting System—may not be fitted to all vehicles.

The RQ-170 could be a candidate for the system described on the UAS road map as MQ-Ma. This was described as close in size to Predator but capable of electronic warfare, and "all weather and modular." In the immediate future, however, the pressure on the Air Force UAV community is to add Reaper combat air patrols in Afghanistan, as the drone war in Pakistan continues and the U.S. follows a strategy of substituting technology for troops in the theater.

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