03 September 2010

Pentagon Bomber Evolution Underway

03 September 2010

X-wing bomber concept (image : Josef Gatial)

The latest analysis of future long-range strike needs by the Pentagon will be submitted in time for its recommendations to be reflected in the Fiscal 2012 budget.

Few people, least of all advocates of an active, nonvintage bomber fleet, expect exciting news. Service-centric politics, a joint-service construct under which ground forces heavily influence the study and pressure on procurement budgets (from overruns in the Joint Strike Fighter program) will result in modest recommendations.

The most likely include the endorsement of a long-range, nonnuclear ballistic missile capability, although the time­scale and budget remain uncertain. The conventional prompt global strike (CPGS) concept is a favorite of Marine Corps Gen. James Cartwright, vice chairman of the Joint Chiefs.

Expect some backing but little money for two other concepts: a joint-service, long-range cruise missile, launched from Virginia-class submarines and B-52s, and the Navy’s Unmanned Combat Air Vehicle (UCAV-N), which may be termed a means of extending the range of a carrier air group. Both systems may be linked to another joint-service study defining a future “air-sea battle” and focused on matching China’s growing power in the Western Pacific.

As for a future USAF bomber, conventional wisdom—i.e., views acceptable to Cartwright and Defense Secretary Robert Gates—is that the idea merits study, over and above several dozen studies carried out in the past decade. In June, Lt. Gen. Philip Breedlove, Air Force deputy chief of staff for operations, plans and requirements, was quoted as saying the word “bomber” can no longer be spoken in the Pentagon and requirements “trickling down from the highest levels” call for a much smaller aircraft. Some sources believe Cartwright is pushing the idea of a USAF variant of UCAV-N.

Air Force Chief of Staff Gen. Norton Schwartz and Secretary Michael Donley have not taken up the cause of a new bomber. The only four-star to support the bomber has been Strategic Command leader Gen. Kevin Chilton.

With little high-level support, bomber advocates are doing what they have done before: changing the name to “reconnaissance-strike.” Lt. Gen. David Deptula, in his last press briefing before retirement, reiterated his view that intelligence, surveillance and reconnaissance (ISR) and attack missions are no longer separate. A penetrating ISR platform that cannot be armed makes little sense.
Industry and service studies of a new ISR and strike platform appear to be converging, driven by technological developments, likely operational requirements and fiscal realism.

Technologically, one factor that has arisen in the past few years is the successful demonstration of extremely low-observable (ELO) technology, with wideband, all-aspect signature reductions of -40 to -50 dB. or more, under one or more covert test programs. One step in this process may have been Boeing’s Bird of Prey demonstrator, with a radar cross section (RCS) so small that visual signatures became dominant. A consultant on that project was stealth pioneer Denys Overholser, who has been involved with projects envisioning RCS levels to -70 dB.—the size of a mosquito.

ELO mandates an all-wing or blended-wing body and tailless, subsonic configuration with buried engines. Advances in the computational analysis of the complicated airflows over such shapes improve aerodynamic efficiency and permit simpler inlet and exhaust systems, putting unrefueled ranges of 5,000 nm. within reach for a “demi-B-2”-sized aircraft. Northrop Grumman mentions an unrefueled range of 5,600 nm. for UCAV-N, with new engines based on advanced commercial cores.

The demonstration of reliable, long-endurance, autonomous operations is important. Many bomber advocates agree that a new ISR/strike aircraft should be optionally piloted. If it acquires a nuclear mission, a crew is likely to be mandatory, and crewing would ease mixed-use airspace concerns. On the other hand, the aircraft would be inherently capable of operations beyond human endurance, and an unmanned mode could avoid sending crews beyond the reach of search-and-rescue assets.

Northrop Grumman concepts for an advanced unmanned ISR/strike system list a range of autonomous functions—threat awareness and avoidance, electronic and lethal countermeasures, and cooperative defense. Onboard sensor fusion and target recognition would be combined with the ability to match imagery with terrain, passing high-grade target information to other assets.

Bomber advocates are monitoring laser weapons in the 100-kw.-class, considered adequate to kill an incoming missile. Combined with ELO, this could give a bomber the ability to survive against current and projected threats.
A survivable aircraft with a large and diverse payload has advantages. It can prosecute targets of uncertain location, and its range is a hedge against antiaccess and area-denial strategies. Unlike the smaller UCAV, it carries a mix of weapons.

The biggest challenge to the bomber is price. Procurement cost in the $500-million range is likely, equivalent to 4-5 JSFs, but carrying 4-5 times the warload five times farther. The total investment in a force of 100 new bombers would be about the same as the cost of replacing Trident submarines. But, as enthusiasts suggest, the bombers would deliver similar or greater longevity and more flexibility. (/Bill Sweetman)


(Aviation Week)

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