DARPA competitively awarded an agreement to Boeing for the DARPA/Air Force UCAV program in 1999. This agreement was to build the X-45A, a small demonstrator aircraft of only about 12,000 lbs take-off gross weight and only 29 ft wingspan. The X-45A was designed strictly as a demonstrator, with its avionics loaded upon a pallet in its bomb-bay and a minimum life expectancy of its airframe. Though it would be the first of its kind - the first aircraft designed from the ground up as a UCAV and not merely a UAV - it would in fact be destined to spend most of its life as a software development tool for the remainder of its family.
Part of the X-45A's unique design was driven by the desire to store the aircraft for long periods in transportable containers. This concept was aimed at reducing the operating and support costs for the vehicles. The containerized UCAV was to have been deployed only when needed for high threat conflicts - perhaps only twice in a ten or twenty year period. All training was to be done via simulation. The containerized UCAV was to be shipped via transport to the area of the fight, where it would deploy at airfields near the scene of action.
The X-45A first took to the air on May 22nd, 2002. Two X-45As were produced and as of 2004 were still in use today at NASA Dryden Flight Research Center. Along with a T-33 surrogate platform, they continued to provide the tools for software development - and continued to break new barriers in unmanned flight. This included the first demonstration of "4-D navigation", the precision control of not just trajectory but timing of the vehicle's movements through the tactical environment - a must for integration of J-UCAS into the mixed manned/unmanned strike packages of the future.
The UCAV Program is on a maximum acceleration schedule that can be defined as a series of overlapping and interrelating spirals. In Spiral 0, Boeing fabricated two X-45A demonstrators and their container and mission control console. We are proceeding through multiple blocks of progressively maturing software and functionality needed for the UOS vision. Block 1 completed initial flight testing, demonstrating the ability to fly and control a single vehicle.
Block 2, which was the summer of 2003, did flight demonstrations of the core of what makes UCAV transformational: multivehicle, coordinated control. Demonstration of that capability culminated in a graduation exercise highlighting the technical feasibility of all aspects of the preemptive SEAD mission. It isn't UCAV until the Block 2 multivehicle operations are demonstrated in flight. That's the heart and soul of what makes the UCAV and why we began this journey of discovery. It is the key enabler for both this program and the other DARPA unmanned systems programs.
The Air Force did a series of tests to show multivehicle, coordinated flight with the T-33 surrogate, proving the ability to bounce control off a satellite from Edwards back to Seattle, to communicate using Link 16, and ton send an update to dynamically retask one of the X-45A vehicles. Finally, the Air Force demonstrated that the vehicle can fly into a zone, take a real emission, react to it, make the maneuvers necessary to obtain a synthetic aperture radar (SAR) image, send that compressed SAR image back, and get authorization from an operator to put a weapon on a target. With the completed demonstration at the end of Block 2, the Air Force had shown the technical feasibility to prosecute the preemptive SEAD mission.
Block 3 started to migrate into the air vehicles themselves intelligence that until then had been only in the ground control station. In the Fall of 2003, in Block 3, the Air Force conducted the first flight demonstrations in the evolution of intelligence from ground to air. The graduation event was two air vehicles hunting for a known target in an unknown location. Working together-without aid from an operator-they will cooperatively found and prosecuted the target, proving the ability to autonomously handle predicted events in unpredicted time. The operator, of course, was still in the loop to interject and override in a supervisory role if necessary. But this demonstrated the first critical step in moving the smarts onto the air vehicle. It was crucial to the end concept that the vehicles themselves have the ability to go in and work together to prosecute and attack. Parallel with that, the Air Force started the next turn of the spiral, Spiral 1.
During a combat air patrol mission to provide airborne coverage over an exercise area on 04 February 2005, two Joint Unmanned Combat Air Systems (J-UCAS) X-45A air vehicles successfully demonstrated basic autonomous reactive suppression of enemy air defenses functionality, concluding Block 3 software testing. Block 3 testing, which began in October 2004, helped to demonstrate a number of the key capabilities required when unmanned combat air vehicles conduct operations in dynamic environments. A single X-45A was commanded to taxi from a parking location to the active runway for takeoff. Along the way, it autonomously stopped itself and executed a pre-takeoff test to verify that its systems were functioning correctly. It then continued to the active runway and waited for the operator to command takeoff. A single X-45A was commanded to taxi, as in the single vehicle autonomous ground operations. Once in place on the runway, the operator cancelled the mission and the vehicle was commanded to return to park in an alternate location. Two X-45A vehicles were commanded as in the single vehicle dynamic taxi, but once on the runway, the operator cancelled the mission. While being redirected and rerouted off the runway, the two vehicles communicated with one another and taxied in formation about the airfield, maintaining a constant safe separation distance from each other. A single X-45A was launched from Edwards Air Force Base/NASA Dryden Flight Center under the control of an operator located at the local mission control station. While in flight, control of the vehicle was handed to an operator in a Seattle mission control station via a beyond-line-of- sight UHF SATCOM link. To verify command and control, the Seattle operator ordered a number of maneuvers and then passed control back to the local Edwards operator for landing.
The Multiple Vehicle Distributed Control demonstration was similar to the single vehicle distributed control demonstration but had both X-45A vehicles airborne when command and control was passed via line-of-sight communications from one mission control station at Edwards/Dryden to a separate mission control vehicle, also located at Dryden. The Reactive Suppression of Enemy Air Defenses demonstration, also called the "Peacekeeping" mission, had two X-45A vehicles patrol separate areas and detect computer-generated pop-up threats. Based on relative vehicle ground speeds to the threat's location, and vehicle weapons load and fuel state, the vehicles made a determination on which vehicle had a better "shot." The operator reviewed the attack plan developed by the system and approved the simulated attacks prior to execution.
Block 4 demonstrations had the X-45A vehicles continue to expand the operations envelope and function more autonomously by "hunting" for enemy threats and charting their own course to avoid the threats while moving into position to attack them. The aircraft will also demonstrate initial cooperative engagement functionality by deciding which vehicle has the optimal position to evaluate or to take action against a target. The J-UCAS program is developing an integrated system incorporating multiple unmanned combat air vehicle platforms and a Common Operating System that are seamlessly linked to achieve shared, interactive control of worldwide operations. The software used and tested on the X-45A may be offered as a candidate for functionality in the development of the Common Operating System.
After completing more than 60 flights, the Joint Unmanned Combat Air Systems (J-UCAS) X-45A flight test program concluded August 11, 2005 with the successful completion of a preemptive destruction suppression of enemy air defenses graduation demonstration. During this demonstration, the two X-45A air vehicles flew the most complex mission scenario to date. The significant tasks completed included: detecting multiple simulated threats; determining which targets were off-limits and which had the highest priority; avoiding simulated "pop-up" threats; replanning attacks when the operator altered target priorities; and performing coordinated multi-ship attacks on multiple targets. After successfully demonstrating each of these capabilities, the two air vehicles safely returned to base.
This foundational program claims many firsts, but one result stands out over all others - the X-45A team did it all safely, completing 64 ground-breaking flights without a mishap. Not many unmanned aerial vehicle programs can make that claim - this team set a new standard.
The X-45A team had been making history in the desert for several years. Under the careful oversight of NASA's Dryden Flight Research Center, Edwards AFB, Calif., and with the Air Force Flight Test Center's continuing assistance, the J-UCAS team had risen to the challenge of achieving the Defense Advanced Research Project Agency's very aggressive goals for these first unmanned combat air vehicle (UCAV) demonstrators.
Since the X-45A first took flight in May 2002, the flight test program has continued to advance the state of the art in unmanned aviation, demonstrating a number of capabilities necessary for successful mission operations. Many also rank as first-of-a-kind in aviation history, including:
- Weapons Release Demonstration, April 4, 2004 - deployment of a GPS-guided weapon from a UCAV;
- Multi-Vehicle Operations Demonstration, August 1, 2004 - operation of two X-45A UCAVs by a single operator;
- Multi-Vehicle Distributed Control Demonstration, July 14, 2005 - in-flight transfer of operator control of two air vehicles to another control station nearly 900 miles away during beyond-line-of-sight flight operations;
- Multi-Vehicle Reactive Suppression of Enemy Air Defenses Demonstration, February 4, 2005 - two X-45As autonomously respond to simulated "pop-up" threats and, with operator consent, engage those threats, including simulating weapons release and battle damage assessment against the targets.
Throughout the early portions of the Air Force UCAV program, missions were studied and refined. The highest priority mission was the suppression of enemy air defenses through lethal and non-lethal means. The X-45A's planned offspring, the slightly larger X-45B, was on its way to being a relatively short range, highly survivable vehicle which could kick the door down for manned strikers.
The next generation of UCAV demonstration systems are the Boeing X-45C and the Northrop Grumman X-47B. These air vehicles, when with combined functionality provided by the J-UCAS Common Operating System, will allow for a robust Operational Assessment to begin in the spring of 2007. The software used and tested on the X-45A may be offered as a candidate for functionality in the development of the program's Common Operating System.
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