In the late 1990s, DARPA and the Air Force began pre-acquisition efforts to conduct advanced technology demonstrations to show the technical feasibility of using UCAVs to penetrate deeply into enemy territory to attack enemy targets. Boeing Corporation was selected in 1999 to develop and demonstrate two demonstrator UCAVs designated X-45A.
Enemy nation's air defenses form a greater threat to US warplanes than a decade ago, and will only become more dangerous in the future.
In future strike missions, the UCAV will conduct the most dangerous task, SEAD, while manned fighter-bombers (like the Joint Strike Fighter for instance) will conduct normal strike missions.
The UCAV will cost about one-third of the cost of next-generation fighter planes. Other advantages are more flexable safety requirements, because the planes are unmanned. This eneables the aircraft to be heavier equipped with munitions and systems than manned aircraft, and besides that, they can also be smaller and lighter.
The first prototype, the X-45A, is representative of the requirements set in 1998, which have since changed.
George Muellner, president of Boeing's Phantom Works, explained that, after assessing the X-45A vehicle, the Air Force decided that it wanted a slightly larger payload and different maneuver tactics. The result is the X-45B model. "It [the vehicle] increased slightly, but I don't think it is going to be dramatic," he said. The basic systems are going to be the same, he emphasized.
The overall length of the vehicle increased by 14 percent, and the wing area grew by 63 percent. The larger wing area offers a wider angle-of-attack range and increases the gust margins, noted Leahy. The UCAV has a 19,000/10,000 pound gross/empty weight respectively, a 500-1,000 nautical miles mission radius and up to a 3,000-pound weapons payload. The X-45B is a 'fieldable' prototype, said Leahy. That could happen in the 2006-2007 time frame. The program has been funded to produce 14 X-45B vehicles by 2008.
The program was not funded past 2003, and it had no money to complete the X-45B development, according to Leahy. "We did receive additional funding that allowed us to fully fund the demonstration program and the development building, the in-flight testing of the X-45 B, and additional funding to develop and procure the 14 Block-10 vehicles," Leahy explained. In fiscal year 2003, the program received $91 million. In March of that year, an X-45 performed an unguided weapons release. In April 2003, it launched a satellite-guided bomb at a speed of nearly Mach 0.7 from 35,000 feet.
In October of 2003 the DARPA/USAF UCAV program and the Naval version, the X-47 UCAV-N, merged into the DARPA/USAF/USNAVY J-UCAS program.
The Defense Department recognized the potential for significant synergy by combining the programs. Both UCAVs will be able to operate independently or be fully integrated with manned aircraft (and other UCAVs) operations, and will incorporate next-generation stealth technologies.
More advanced demonstrators were then developed as part of the J-UCAS program: the X-45C and X-47B, they we the next step in the evolution of an affordable operational J-UCAS.
The larger air vehicles will more closely represent the envisioned operational systems, to include two full weapons bays and incorporation of low observable (LO) technologies. External views of the two air vehicle concepts are provided below:
Boeing's X-45B version was simply a larger version of the X-45A:
In April 2003, while Boeing was designing the X-45B version, DARPA asked Boeing to modify its B design to cost effectively meet both the Air Force's evolving need for greater range and loiter capability and the Navy's objectives in their DARPA-led UCAV-N demonstration program.
The B design then became the base for the X-45C version. Especially the subsystems and center body of the X-45B were used for the X-45C, though the planform did change significantly. The C version carries more fuel and has a better aerodynamic shape.
With the increase fuel capacity, the X-45C trippled the combat radius of the B variant, with the same payload.
On June 8th, 2004, Boeing began assembling the X-45C. The C configuration will be approximately 39 feet long with a 49-foot wingspan and cruise at 0.85 Mach.
Despite being only a few feet thick, its maximum payload will be 4,500 pounds and it will carry 8 Small Diameter Bombs, Boeing's newest near-precision 250-pound weapon. This revolutionary combat vehicle will fly at 40,000 feet with a mission radius of 1,300 nautical miles.
The first flight of the X-45C air vehicle was scheduled for early 2006, but the Pentagon decided to cancel the X-45 program, in order to concentrate on it's new long-range strike bomber program.
Three capabilities are essential for the Next Generation Long Range Strike Aircraft program:
So, the technology developed for the UCAV program can still be used for this new long-range strike program. The X-45C could also be modified to compete in the Navy's unmanned carrier-based aircraft program, but it was designed to land only on a runway. It's J-UCAS program counterpart, Northrop Grumman's X-47 Pegasus has the advantage, it was designed from the start to land on an aircraft carrier.
"These programs have been restructured and canceled and resurrected a half dozen times over the last couple of years," chief executive of Boeing's St. Louis-based defense business said. "And I think we'll be in good shape as these programs get reconfigured."
| Version | X-45 A | X-45 B | X-45 C |
| Manufacturer | Boeing | Boeing | Boeing |
| Country | USA | USA | USA |
| Type | Unmanned Combat Aerial Vehicle | Unmanned Combat Aerial Vehicle | Unmanned Combat Aerial Vehicle |
| Powerplant | Honeywell F124-GA-100 (1x) | GE F404-GE-102D (1x) | GE F404-GE-102D (1x) |
| Thrust | 6,300lbs 28kN | 7,000lbs 31.1kN | 7,000lbs 31.1kN |
| Length | 26.3ft 8.02m | 36ft 9.6m | 39ft 11.7m |
| Height | 3.7ft 1.13m | 4ft 1.3m | 4ft 1.3m |
| Wingspan | 33.8ft 10.30m | 47ft 14.3m | 49ft 15m |
| Weight | 12,000lbs 5,529kg (Take-Off) | 36,500lbs 16,556kg (Take-Off) | 36,000lbs 16,329kg (Take-Off) |
| Speed | 0.75 Mach | 0.85 Mach | 0.85 Mach |
| Ceiling | 35,000ft 10,670m | 45,000ft 13,720m | 40,000ft 12,000m |
| Crew | unmanned | unmanned | unmanned |
| Unit cost | $10 - $15 million | $10 - $15 million | $10 - $15 million |
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