May 26, 2008
Bill Sweetman/Minneapolis
NGB demonstrator may be a twin-engine aircraft resembling an X-47B. Initial version will be piloted, but an unmanned endurance version is a probable follow-on.
Is Northrop Grumman building a secret bomber prototype? In late April, the company revealed first-quarter financial results. Data indicated $2 billion in new "restricted programs" contract awards at Integrated Systems, the aircraft division. This almost certainly confirms what DTI first reported earlier this year: Northrop Grumman has a classified, sole-source contract to build a demonstrator for the U.S. Air Force's Next-Generation Bomber (DTI March, p. 30).
USAF budgets show no funding for the Next-Generation Bomber (NGB) itself in 2008, although documents show money for technology work in Fiscal 2008-10. Northrop Grumman CEO Ron Sugar said last year that Integrated Systems had made strides in black programs and identified restricted projects as the top new-business opportunity. Taken together, the evidence points to a single, very large contract win. Northrop Grumman also acquired Scaled Composites in 2007, a company that can develop large prototype aircraft quickly.
The $2-billion contract casts new light on the decision in January by Boeing and Lockheed Martin to reveal their year-old collaboration on NGB. (Boeing, Lockheed Martin and Northrop Grumman declined interview requests.) Hailed as an NGB "dream team" combining Boeing's bomber experience with Lockheed Martin's stealth technology, the teaming now looks like an effort to catch up with a rival that has a lead in the next major U.S. combat aircraft program.
It is likely that the prototype will build on technology under development for the Navy's X-47B Unmanned Combat Air System Demonstrator (UCAS-D), putting within reach USAF's goal of a 2018 initial operational capability date for the bomber. Industry and USAF sources have talked about a competition in 2010, leading to the start of systems development and demonstration in 2011. But it would be Northrop Grumman's to lose.
Events since 2000 placed Northrop Grumman in pole position. USAF interest in a replacement bomber was rekindled after 9/11, but USAF Secretary Jim Roche and Chief of Staff Gen. John Jumper focused on the Lockheed Martin FB-22, seeing it as a low-risk solution that bolstered the case for the embattled F-22.
The departures of Roche and Jumper in 2005 coincided with a change in thinking. In October, USAF defined a three-stage Next-Generation Long-Range Strike program. Phase I would keep the force effective until 2018, with upgrades to aircraft. Phase II would be a new "2018 bomber," while Phase III encompassed hypersonic concepts. This was the end of the road for the FB-22, since nobody envisioned the F-22 remaining in production long enough to dovetail with Phase II.
Late in 2005, at a conference on unmanned combat air vehicles in London, there were signs of convergence between the bomber requirement and the Joint UCAS project. J-UCAS had been kicked off as a major effort three years earlier, but USAF was interested in a platform larger than the Navy could accommodate.
Northrop Grumman J-UCAS Program Manager Scott Winship said at the time that the company had proposed completing a third prototype as an X-47C with a 172-ft. wingspan and 10,000-lb. payload. J-UCAS leader Mike Francis stressed an advantage of the unmanned vehicle: an inherently lower radar cross-section (RCS) than conventional tailed aircraft.
Despite the tension in J-UCAS, it was a surprise when an early-2006 high-level Pentagon review killed it, splitting resources into a white-world Navy effort and a classified USAF program, while endorsing a plan to field a bomber in 2018.
It's now apparent, however, that USAF had already picked a primary approach to the NGB, and that the next two years of work, starting with the remaining Fiscal 2006 J-UCAS funding, are intended to validate that choice.
This approach emerged from J-UCAS, and particularly from Northrop Grumman, which anticipated the J-UCAS split and was prepared to respond. The company believed that the basic 42,000-lb. J-UCAS was better suited to the Navy than to USAF, had focused on the carrier-based J-UCAS demonstration and picked a design that offered high lift and a simple wingfold.
Northrop Grumman's proposal for a bigger X-47C also preceded -- and may have inspired -- USAF's switch to a larger long-range bomber. This meant, too, that the NGB program could get a running start because it would use aerodynamics and stealth technology that were in the works for J-UCAS.
The X-47B was much more advanced, in aerodynamic terms, than it appeared (see sidebar), and the same is likely true of its low-observable (LO) qualities. The aircraft is one of the first to combine a highly blended tailless configuration with new materials developed since the 1980s. The NGB will be the same, if not more so.
Northrop Grumman has stressed the "all-aspect, broadband" stealth inherent in the X-47B. Tailless shapes don't have the "bow-tie" RCS pattern, with the smallest RCS on the nose and tail and peaks on the beam configurations, which characterizes conventional aircraft. They are stealthier against low-frequency radars -- including updated, active-array VHF radars marketed by Russia -- because they do not have shape features which are so small that their RCS in the VHF band is determined by size, rather than shape or materials. It may be significant that John Cashen, leader of the B-2 signatures team, returned in 2006 after 10 years in Australia and is now a consultant for Northrop Grumman.
RCS test facilities across the U.S. have been upgraded since the F-22 and B-2 were designed: USAF's range at Holloman AFB, N.M., was reequipped to handle bistatic measurements, and a sophisticated airborne RCS measurement program based on a modified 737 was delivered in 2001.
How low can LO go? One paper, co-authored by a principal in DenMar Inc., the company founded by Stealth pioneer Denys Overholser, refers to the development of fasteners for a body with an RCS of -70 dB./sq. meter -- one-thousandth of the -40 dB. associated with the JSF, and one-tenth that of a mosquito. DTI queried RCS engineers who don't believe such numbers are possible; but then, when mention of a -30 dB. signature leaked out in a 1981 Northrop paper, nobody believed that either.
Concept Image: Jozef Galtial for DTI
Source
http://www.aviationweek.com/aw/generic/story_generic.jsp?channel=dti&id=news/DTI-Bomber.xml&headline=Ultra%20Stealth
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