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Document created: 3 June 02
Aerospace Power Journal - Summer 2002
Focus: Unmanned Aerial Vehicles

Unmanned Combat Aerial

Dawn of a New Age?

Col Robert E. Chapman II, USAF

Editorial Abstract: The use of unmanned combat aerial vehicles in the skies over Afghanistan is just beginning to awaken the Air Force to the enormous potential of these aircraft. In this informative article, Colonel Chapman summarizes current developments regarding these vehicles and gives us a glimpse into their possible employment in the future.

The Department of Defense (DOD) has recently accelerated efforts to develop unmanned combat aerial vehicles (UCAV)- aircraft that can launch, attack, and recover without crew members aboard. Advocates contend that an array of technologies has now matured to the point that fielding an operational UCAV is both feasible and desirable. UCAV proponents project significantly lower acquisition costs, as well as operations and support costs. Such projections are particularly attractive in the current fiscal environment, in which all military services urgently need to replace aging capital equipment. Proponents further contend that a reusable vehicle capable of delivering precision munitions could significantly lower the cost per target killed below that of the current generation of standoff weapons.

Background: Why a UCAV?

Over the last decade, the combined airpower of the US military has proved instrumental in favorably deciding military actions in Iraq, Bosnia, and Kosovo. American airpower in all its forms constitutes a unique and decisive military advantage no other nation can match. However, growing concern exists within the national security community that this advantage may be eroding. A number of potential adversaries are pursuing advanced weapons systems that could deny or restrict America’s future ability to project combat power abroad. Of particular concern are increasingly lethal integrated air defense systems (IADS) and mobile surface-to-surface missile systems. Many analysts believe that the United States must develop means to counter those threats if it is to maintain its ability to project decisive combat power abroad. UCAVs could offer one option to combat the worldwide proliferation of these access-impeding weapons.

Potential Advantages

Although airmen have long recognized the promise of UCAVs, thus far they have remained beyond the grasp of developers.1 Recent advances in technology, however, have prompted many national security planners to reevaluate UCAV feasibility.

Cost per Target Killed. Advocates assert that UCAVs employing direct-attack munitions could reduce costs per kill well below that of current standoff systems- cruise missiles, for example. During Operation Desert Fox, a 70-hour joint military operation ordered by the president in December 1998 to destroy military and security targets in Iraq, Navy ships fired more than 325 Tomahawk cruise missiles, and Air Force B-52s launched more than 90 AGM-86C conventional air launched cruise missiles (CALCM).2 These weapons carry warheads weighing 1,000 pounds and 2,000 pounds, respectively.3 Alternatively, proponents argue that reusable UCAVs could achieve the same effect at far less cost by delivering 1,000-pound and 2,000-pound joint direct attack munitions (JDAM) guided by the Global Positioning System (GPS) (table 1). UCAV proponents argue that the cost-per-kill contrast becomes even greater when one considers procurement, operating, and support costs of the associated launch platforms. The cost implications for future military operations will merit examination once detailed UCAV data becomes available.

Table 1
JDAM Unit-Cost Comparison

Tomahawk CALCM  JDAM
Warhead 1,000 lb 2,000 lb 1,000/2,000 lb
Unit Cost  $600,000   $1,160,000 $21,000

Sources: “Tomahawk Cruise Missile,” United States Navy Fact File, 28 November 2000, on-line, Internet, 6 March 2002, available from http://www.chinfo.navy.mil/navpalib/factfile/missiles/ wep-toma.html; and “AGM-86B/C Missiles,” USAF Fact Sheet, n.d., on-line, Internet, available from http://www.af.mil/news/factsheets/AGM_86B_C_Missiles.html. JDAM cost is for tail-kit modification to existing Mk 83 and Mk 84 conventional bombs (response to inquiry, Office of the Secretary of the Air Force, Weapon Systems Liaison Division, 14 May 2001).

Design. UCAV proponents contend that removing the operator from the weapons-delivery vehicle confers design advantages over manned aircraft. First, since vehicle loss does not pose an inherent risk to human life, design margins can be reduced below the traditional 150 percent design load factor traditionally used for manned aircraft.4 Lower design margins lead to reductions in structural weight. Second, the elimination of pilot-support systems, such as egress mechanisms and environmental controls, also reduces weight and complexity. Collectively, these savings can result in smaller vehicle sizes.

Operation. UCAV proponents cite several potential operational advantages over manned systems, pointing out that smaller vehicle sizes yield greater range and endurance. Additionally, smaller vehicles possess inherent survivability advantages because radar cross-section and infrared signatures are reduced. They argue that the absence of the cockpit, typically a large area of radar reflectivity and a significant contributor to radar signature, would further enhance UCAV survivability. UCAV advocates assert that smaller vehicle sizes may have even greater survivability implications in the future as new detection and tracking technologies mature (e.g., long-wave infrared and vortex-generation detection, which exploits airflow disturbances caused by aircraft).

Finally, without the risk of aircrew loss, vehicle attrition becomes less onerous from both a moral and a political standpoint. One could task UCAVs for high-risk, high-payoff missions without attendant risk to human life. As a result, UCAVs could expand the range of coercive options available to both civilian and military leaders.

Potential Contributions to an Air Campaign

UCAV proponents argue that a fleet of low observable (LO) UCAVs could contribute to the success of an air campaign in a number of ways. First, UCAVs could provide a powerful “day one” force enabler by conducting destruction of enemy air defenses (DEAD) and suppression of enemy air defenses (SEAD) missions. DEAD, the physical destruction of known elements of an enemy’s IADS, plays an essential role in the success of a general air campaign by creating a survivable environment for the nonstealthy strike aircraft that comprise the bulk of America’s aviation force structure. Second, UCAVs could be used to supplement deep-penetration strike aircraft, such as the B-2 and F-117, by conducting conventional attacks against strategic fixed targets and enemy centers of gravity. Although the Air Force currently operates LO platforms capable of conducting this mission, the Navy does not. A carrier-based LO UCAV could provide naval aviators with a long-sought, survivable, day-one, deep-strike capability. Finally, operating as part of a general air campaign, long-loiter UCAVs could provide a persistent presence to rapidly strike time-critical targets such as mobile surface-to-surface missile systems or armored vehicles out of garrison.

UCAVs might also play an important role in low intensity conflict or contingency operations. Low observability, long endurance, and the absence of pilot support are ideal attributes for long-duration missions in hostile or contested airspace. Proponents envision UCAVs conducting armed-reconnaissance missions, patrolling the skies over hostile territory, and holding enemy targets at risk in a manner similar to missions currently ongoing over Iraq as part of Operations Southern Watch and Northern Watch.

Additionally, UCAVs might reduce demands on support assets such as combat search and rescue (CSAR) forces. These scarce resources, characterized by DOD as high-demand/low-density assets, are tasked with the hazardous mission of recovering downed aircrew members. In the event of a UCAV loss, CSAR efforts would be unnecessary. Reducing rescue requirements directly lowers the risk of CSAR force attrition. Lastly, UCAVs could enhance a theater commander’s ability to maintain a robust air campaign in the presence of chemical or biological agents because these vehicles would obviate the inefficiencies imposed by aircrew physiological-support requirements in such an environment.

Notional Concept of Operations

The potential application of UCAVs to the DEAD/SEAD mission is of particular interest to the services. The Air Force characterizes this mission, a subset of air superiority, as both high risk and high payoff. Successful destruction or suppression of enemy air defenses is a paramount concern in the execution of an air campaign.

DEAD missions are typically characterized by short-decision timelines and target systems consisting of mobile, relocatable, and fixed components. The DEAD mission is notoriously hazardous because weapons employment typically requires the launching of aircraft to operate within the lethal envelopes of enemy surface-to-air missiles. Frequently, DEAD aircraft must intentionally stimulate enemy systems by placing themselves at risk in order to employ antiradiation missiles.

Most national security analysts agree that the DEAD/SEAD mission is both critical and inadequately addressed. Lt Gen Michael Short, USAF, retired, who served as joint force air component commander for Operation Allied Force and commander of NATO’s Allied Air Forces Southern Europe, cited the need for additional DEAD/SEAD capability as one of the principal lessons learned from the recent Kosovo air campaign.5 Many national security professionals are hopeful that UCAVs will become an affordable solution to the DEAD/ SEAD shortfall.

However, some defense analysts contend that UCAVs will lack the utility and effectiveness of manned aircraft. They question whether these vehicles can provide the same level of adaptive decision making and responsiveness to mission changes that manned aircraft provide. Moreover, UCAV critics raise doubts regarding their affordability, based on still-emerging technology, and question whether their operational value will justify the cost. The Defense Advanced Research Projects Agency (DARPA) has embarked on two demonstration projects that directly address these concerns- the UCAV Advanced Technology Demonstration (ATD) and the UCAV-N ATD, a naval version.

Unmanned Combat
Aerial Vehicle Advanced
Technology Demonstration

The UCAV ATD (fig. 1) is a joint effort between DARPA and the Air Force. Led by DARPA, the program seeks to demonstrate the technical feasibility of a UCAV system that can effectively and affordably prosecute SEAD and strike missions.6 ATD aims to 

Figure 1. UCAV ATD (From briefing, subject: DARPA/USAF Unmanned Combat Aerial Vehicle Advanced Technology Demonstration Program Overview and Status Update, July 2000)

Figure 1. UCAV ATD (From briefing, subject: DARPA/USAF Unmanned Combat Aerial Vehicle Advanced Technology Demonstration Program Overview and Status Update, July 2000)

design, develop, integrate, and demonstrate both critical and key UCAV technologies, processes, and system attributes. Critical technology areas to be explored include adaptive autonomous control; advanced cognitive-aids integration; secure and robust command, control, and communication; and compatibility with the integrated battle space.7 As they pursue specific objectives (table 2), UCAV ATD program officials hope to define the design elements of an operational UCAV system and develop life-cycle cost models that will include 80 percent confidence estimates of acquisition as well as operations and support costs.8

Table 2
UCAV ATD Program Objectives

• Develop and demonstrate a low-life-cycle-cost, mission-effective design for a SEAD/ strike unmanned aerial vehicle (UAV).

• Develop a reconfigurable control station for multiship operations.

• Develop robust/secure command, control, and communications, both within line of sight and beyond line of sight.

• Evaluate human/computer function allocation, dynamic mission planning, and management approaches.

• Evaluate off-board/onboard sensor integration, weapon targeting, and loadouts.

• Demonstrate human-in-the-loop detection, identification, location, real-time targeting, weapons authorization, weapons delivery, and target-damage indication.

• Continue refinement of the operational SEAD/strike UCAV design and assessment of its projected effectiveness and affordability.

Source: Briefing, subject: DARPA/USAF Unmanned Combat Aerial Vehicle Advanced Technology Demonstration Program Overview and Status Update, July 2000.

UCAV System Description

UCAV ATD efforts are focused on maturing and validating technologies that could eventually form the basis of an operational UCAV weapons system. Designers are conducting numerous design trade studies and constructive analyses aimed at optimizing UCAV effectiveness and affordability. To validate design elements of an operational UCAV, program officials are developing a UCAV Demonstration System (UDS)- not an operational prototype but a set of tools to assist in the definition of a suitable operational weapons system. However, it is possible that a number of UDS elements eventually could be iteratively refined and incorporated into an operational UCAV design. UCAV ATD efforts are distributed among three distinct segments: air vehicle; mission control, including communications architecture and operator interface; and supportability, including operator training, vehicle maintenance, and logistics.

Air Vehicle Segment. The demonstration air vehicle, designated X-45, is a tailless stealth platform that designers believe would be suitable for survivable deep-penetration missions. With an overall length of 27 feet and a wingspan of 34 feet, it is smaller than manned fighters carrying comparable payloads. The relatively small size of the vehicle, coupled with its internal weapons carriage, would provide an operational vehicle with a distinct advantage in its ability to avoid detection by threat systems. 

The demonstration aircraft will have an empty weight of approximately 8,000 pounds and will be powered by a single business-jet-class engine (nonafterburning). Designers have selected the Honeywell F124 engine as the power plant for the first two vehicles. Program officials believe that this engine, designed to produce 6,300 pounds of thrust,9 will propel the vehicle to approximately 480 nautical miles per hour at 40,000 feet and provide a flight duration of about 90 minutes. The engine face is fully shrouded by a serpentine inlet for signature reduction. A yaw thrust-vectoring nozzle, derived from previous UAV programs, enhances flight-control authority. Program officials believe that many X-45 design details could transfer directly to an operational vehicle.

Program officials are looking ahead to an operational UCAV optimized for DEAD but possessing the inherent ability to penetrate an advanced IADS and attack fixed targets. This vehicle concept features the ability to carry a variety of conventional payloads. Primary payload options for each of the two internal UCAV Operational System (UOS) weapon bays could include six 250-pound GPS-guided small smart bombs, eight Low Cost Autonomous Attack System (LOCAAS)10 submunitions, two advanced antiradiation missiles, or one Mk-83 1,000-pound JDAM. Loads could be mixed between bays to enhance operational flexibility. Program officials contend that the system’s weapons capabilities will allow it to conduct attacks against 80 percent of projected enemy target sets. An operational vehicle might also incorporate other weapons currently in development. Among these are an information-operations/ electronic-attack payload and a directed-energy payload. Other weapons-bay options include an intelligence, surveillance, and reconnaissance payload; supplemental fuel; or countermeasures dispensers.

Designers also envision that an operational UCAV will feature a robust avionics suite. To accomplish the DEAD mission, the air vehicle will be equipped with electronic-surveillance measures. The components could precisely geo-locate targets of interest by triangulating received signals using time-difference-of-arrival techniques. Program officials believe that a flight of three cooperatively targeting UCAVs will be capable of determining an emitting threat radar’s position to within roughly 50 meters. Using its high-resolution synthetic aperture radar (SAR), the vehicle could then map the area of interest to determine precise target locations. From the resulting SAR image, one could compute coordinates with sufficient accuracy to enable employment of GPS-based weapons. Cooperative operations between both UCAVs and manned systems could occur through ultrahigh frequency (UHF), Link 16, and satellite communications. Finally, to enhance supportability and facilitate long-term storage, designers envision that an operational vehicle’s flight controls and secondary systems would be electrically powered, thus eliminating traditionally maintenance-intensive hydraulic systems.

Mission-Control Segment. Using commercial, off-the-shelf hardware, program officials are developing a reconfigurable mission-control system that could ultimately serve as an integrated command, control, and intelligence node with links to a wide array of national- and theater-intelligence sources. The trailer-based system features both line-of-sight communications and a satellite relay for beyond-line-of-sight mission control. By employing a layered command-and-control architecture modeled after the Internet, designers believe that the mission-control system will eventually provide sufficient situational awareness and decision aids to enable a single operator to control up to four vehicles simultaneously. Transferring the decision-aiding software from ground-based consoles to the air vehicle will be one of the key challenges in the demonstration.

Supportability Segment. The supportability segment aims to minimize both the operating costs and footprint of the system. Central to the program’s design philosophy is the capability for long-term system storage. Program officials project that operational UCAVs, with wings detached, could be housed in their own sealed, deployable storage containers (fig. 2) for up to 10 years. The containers would be powered to allow humidity control and vehicle diagnostics. Networked connections would allow maintainers to monitor vehicle health and configure onboard software. The transportable containers would increase the UCAV’s deployment options beyond system self-ferry, with a single C-17 carrying up to six containerized UCAVs. As part of the demonstration effort, the contractor will construct two full-scale UDS vehicle containers.

Figure 2. Artist’s Conception of Vehicle Storage Container

Figure 2. Artist’s Conception of Vehicle Storage Container (From briefing, subject: DARPA/USAF Unmanned Combat Aerial Vehicle Advanced Technology Demonstration Program Overview and Status Update, July 2000)

Program officials contend that long-term system storage not only is viable, but also is capable of yielding significant life-cycle cost savings. One area of potential cost savings lies in operator-proficiency training. Unlike pilots of manned aircraft, UCAV operators would receive no direct sensory inputs on vehicle performance- the control console would synthetically generate all performance cues. Consequently, program officials believe that modeling and simulation can effectively provide substantial portions of operator training. Virtual proficiency training could substantially reduce the number of actual training flights required, yielding a corresponding reduction in the vehicle’s operating and support costs. Significant savings could accrue from reduced personnel costs, a sizable contributor to operating and support costs. One would need a full complement of unit personnel only when UCAVs operate at wartime flying rates. As a result, program officials are exploring unit-manpower concepts based on up to 80 percent manning by Reserve personnel. Preliminary analysis indicates that a UCAV squadron could achieve a reduction in operating and support costs of at least 75 percent, compared to costs associated with an F-16 squadron equipped with high-speed antiradiation missiles, the Air Force’s current DEAD workhorse.

UCAV ATD Program Structure

Officials contend that the three-phase UCAV ATD program (fig. 3) will allow decision makers to determine the technical feasibility and fiscal prudence of pursuing an operational UCAV weapons system. Each phase contains a series of performance-based milestones that determine the efficacy of proceeding to the next phase. If one can meet these milestones, DARPA and Air Force program officials believe that the UCAV ATD could form the foundation for a follow-on, low-risk engineering, manufacturing, and development (EMD) effort that might yield an operational weapons system.

Figure 3. UCAV Transition Plan

Figure 3. UCAV Transition Plan (From briefing, subject: DARPA/USAF Unmanned Combat Aerial Vehicle Advanced Technology Demonstration Program Overview and Status Update, July 2000; and Department of Defense Report on Unmanned Advanced Capability Combat Aircraft and Ground Combat Vehicles [Washington, D.C.: Department of Defense, March 2001])

Since entering phase two in March 1999, program efforts have focused on UDS design development. As part of that task, Boeing, the prime contractor, will build two demonstrator systems, each consisting of an X-45A air vehicle, mission-control system, air-vehicle container, and associated system-support equipment. The X-45A demonstration air vehicles will be constructed in a manner consistent with the LO design details envisioned for operational vehicles, including external, signature-driven surface characteristics and internal structural layout; however, they will not fully incorporate LO materials, treatments, or apertures. A number of planned simulator, ground, and flight tests will demonstrate system maturation.

Once the flight-test phase begins, initial emphasis will be on validating basic vehicle-control concepts using a single air vehicle with line-of-sight UHF links. Early flight tests will focus on navigation; exploration of operator-interface options; contingency management, such as the loss of off-board communication signals; and distributed control procedures to transfer vehicle control between two noncollocated ground-control stations.11 A second flight-demonstration period will utilize two X-45As to demonstrate multivehicle control for both basic flight and mission tasks. Flight tests are intended to validate intervehicle control using the Multifunctional Information Distribution System/Link 16 architecture. Flight-test period two is scheduled to culminate in a full mission demonstration consisting of preemptive DEAD employment against a simulated enemy surface-to-air missile site.12

If phase two proves successful, program officials hope to enter a third phase of the UCAV ATD, currently forecast to begin in October 2003. That phase would focus on risk reduction and operational evaluation to facilitate a low-risk entry into EMD between 2005 and 2007, depending upon funding profiles provided.13 During phase three, program emphasis would shift from validating technical feasibility to exploring operational utility. Program officials acknowledge that their key technical challenge in this phase will entail achieving higher levels of onboard vehicle autonomy and cooperative targeting by migrating the intelligent, decision-aiding software developed for the mission-control station onto the air vehicle’s mission-management system. From an operational perspective, program officials see their greatest challenge as achieving seamless UCAV interoperability with a strike package consisting of manned aircraft.14

Part of phase three would include construction of a third demonstrator system featuring the X-45B air vehicle, which would incorporate all LO design elements envisioned for the UOS to allow for in-flight signature validation and evaluation of LO maintainability. Additional periods of simulation, ground, and flight test are planned, eventually culminating in a full mission demonstration during which several X-45s will operate in conjunction with manned aircraft as part of a joint strike force.15 If the demonstration proves successful, DOD officials believe that initiation of an EMD effort in 2007 might yield an initial operational capability in fiscal year 2015.16

Naval Unmanned Combat Aerial
Vehicle Advanced Technology

The UCAV-N ATD (fig. 4), a joint effort between DARPA and the Office of Naval Research, seeks to demonstrate the technical feasibility of a UCAV system that can effectively and affordably provide persistent, sea-based SEAD, strike, and surveillance capability.17 The program proposes to extend knowledge gained from the UCAV ATD into the maritime environment and examine aspects of UCAV operations unique to the Navy.

Figure 4. Artist’s Conception of a Naval UCAV on Approach

Figure 4. Artist’s Conception of a Naval UCAV on Approach (Reprinted, by permission, from Northrop Grumman Corporation)

UCAV-N program goals for SEAD and strike are virtually identical to those of the Air Force program. UCAV-N program officials wish to leverage the results of the Air Force UCAV program to avoid duplication of effort. They characterize the interplay between the two programs as “almost a leader-follower relationship” and plan to explore only those areas that are significantly different in their naval applications or those emerging areas that promise advantages to both programs.18

UCAV-N System Description

Like the Air Force UCAV, the UCAV-N will conduct both preemptive and reactive DEAD missions as well as strike missions against fixed, relocatable, and mobile targets. The UCAV-N differs significantly from the Air Force version in three areas. First, it has adopted a 12-hour endurance goal to facilitate both maritime and battle-area surveillance. Second, the system must operate, launch, and recover in the crowded and confined carrier environment. Moreover, it must do so without imposing costly modifications to the ship’s layout or disrupting the well-established routine of the carrier’s operating cycles. Finally, the UCAV-N vision includes daily peacetime flight operations with no provision for long-term, dormant system storage. Again, like the Air Force UCAV, UCAV-N ATD efforts are distributed among three segments- air vehicle, mission control, and supportability.

Air Vehicle Segment. Designs for the demonstration vehicle have not been finalized. Contractor teams are still defining their vision for an operational UCAV-N and designing an appropriate demonstration system. Some general vehicle characteristics, however, are emerging. As in the case of the Air Force UCAV, UCAV-N contractor teams are pursuing tailless, LO platforms optimized for high-altitude, subsonic cruise and featuring an internal weapons carriage. Senior program officials anticipate contractor proposals for an aircraft with an empty weight of 10,000 to 15,000 pounds.19 Weapons payload is likely to exceed 4,000 pounds.

Program officials also anticipate that both contractor teams will propose designs that take off and land from a large-deck carrier in the same manner as conventional aircraft. UCAV-Ns likely will perform catapult-assisted takeoffs and arrested landings, although the teams have considered short-takeoff/vertical-landing options. The program’s goal is for operational UCAV-Ns to integrate seamlessly with manned flight operations. Ideally, UCAV-N launches and landings would be staggered so as to minimize conflict with manned aircraft, but program officials maintain that the vehicle must land and clear the arresting cable within 45 seconds, as manned aircraft must do. Within the Navy, many aviators remain skeptical of the UCAV’s ability to integrate with manned flight operations and have expressed concerns regarding potential disruptions and safety hazards to sailors and equipment on deck. Clearly, service support for the UCAV-N will be predicated largely on the ability of program officials to allay these concerns.

Mission-Control Segment. Carrier integration of the mission-control system represents a unique UCAV-N design challenge. Many elements of vehicle control, particularly tactical control elements such as those required in SEAD and strike profiles, will be common to the Air Force UCAV, but recovery aboard ship is a unique and challenging UCAV-N issue. Notionally, one can achieve basic vehicle navigation, including entry into the carrier’s traffic pattern, using onboard GPS equipment. Once established on final approach, glide slope and azimuth information- necessary for precise, all-weather landings- could be obtained through a shipboard-relative GPS, a developmental system that computes relative carrier motion.

System designers are constructing a number of redundant control nodes intended to ensure that UCAV-Ns will be able to recover aboard a carrier safely. During the final portion of a UCAV-N’s landing approach, cancellation authority would reside in several man-in-the-loop links. UCAV-N operators stationed both in the carrier air traffic control center and the mission-control station would be able to command a wave off, as would the landing-signals officer on deck. Through the shipboard-relative GPS communications link, that officer would be able to monitor a wide array of flight data, including relative vehicle position, velocity, acceleration, glide-slope deviation, airspeed, angle of attack, and sideslip.

Designers are also addressing the challenge of maneuvering UCAV-Ns on deck after a successful arrested landing. Among the available deck-handling technologies, the most promising concept appears to be equipping dedicated UCAV-N maintenance personnel with a wireless, hand-held control device to input real-time commands to the vehicle. Essential system characteristics include positive control and redundant shutdown capabilities, which would protect sailors working on deck.

Supportability Segment. Unlike the Air Force program, the UCAV-N program does not include integrated storage and shipping containers. Program officials envision that UCAV-Ns will fly daily to provide real-time surveillance for the battle-group commander. This operating concept poses a significant supportability challenge- namely, conducting daily flight operations in the harsh marine environment without the need for routine restoration of LO airframe components. Developing LO materials appropriate for the naval environment has impeded previous efforts to field an LO naval aircraft. Even in land-based stealth programs, signature maintenance has imposed a significant supportability burden. Program officials hope to leverage development efforts for the joint strike fighter to achieve an affordable and supportable stealth vehicle.

UCAV-N ATD Program Structure

Much like the Air Force UCAV ATD, the UCAV-N ATD is a three-phase program that, according to officials, will allow decision makers to determine the technical feasibility and fiscal prudence of pursuing an operational maritime UCAV weapons system. Each phase consists of performance-based milestones used to determine the efficacy of proceeding to the next phase. As in the case of the Air Force program, DARPA and Navy program officials hope that UCAV-N ATD success will warrant entry into a low-risk EMD effort that could yield an operational weapons system.

In phase one of the program, begun in July 2000, program officials are refining operational-system concepts; identifying critical technologies, processes, and system attributes; developing a system-maturation plan; and defining demonstration-system requirements. These officials plan to incorporate lessons learned from the Air Force UCAV program and align the program to enable further cooperative efforts.

Planned UCAV-N efforts in phase two entail risk-reduction activities, including designing, developing, and flight-testing a UCAV-N demonstration system. One of the primary objectives of the phase-two trials involves validating the control-and-communication attributes required to launch and recover a UCAV-N on a carrier deck. Program officials seek to maintain a competitive environment by retaining both contractors through at least the end of this phase.

If phase-two efforts prove successful, program officials anticipate entering a yet-to-be-defined third phase- risk reduction and operational evaluation- as a precursor to a possible EMD effort. Although an appropriate decision point for EMD entry remains undetermined, these officials continue to explore potential EMD options. One planning constraint is that the timeline for UCAV-N development is wedded to that of the lead Air Force UCAV program. If the latter achieves its development milestones as forecast, program officials believe it would be possible to begin a UCAV-N EMD effort in 2010, possibly resulting in a fielded system by 2015.20 Additionally, a number of aircraft producers in the United States and Europe are reportedly pursuing UCAV development efforts (table 3).

Table 3
Selected UCAV Demonstration/Development Programs

Program Country Manufacturer Description Empty
Weight (lb)
Defense and
Space Co.
EADS Military
LO surface-attack
9,923 18,078 Internal
carriage of
France Dassault
Subscale demonstrator
of LO surface-attack
77  132 N/A
Sweden Saab
LO surface-attack unknown 11,023 Internal
carriage of
USA  Lockheed
Aircraft-launched, LO
UCAV designed to
attack air defense
unknown unknown

One or two
small bombs
or nonlethal
payloads (e.g.,

Pegasus USA  Northrop
demonstrator to explore
LO UCAV carrier
3,835  5,500 Internal
carriage of
two 500 lb
RQ-1B Predator
USA General
Medium-altitude, armed
 reconnaissance vehicle
for real-time targeting of
armored vehicles 
950 2,250 Two AGM-114
 Hellfire C anti-

  Technical Challenges
and Concerns

Both DARPA and service officials characterize the UCAV and UCAV-N as high-risk, high-payoff programs. Consequently, program officials have instituted a number of measures to monitor and manage risk. Of particular concern to developers are systems-integration issues such as seamless compatibility with other battle-space information systems; a secure and robust communication capability; and adaptive, autonomous operations.

Battle-space integration, pivotal to UCAV success, will require network-integrated software capable of supporting multisensor cooperation, dynamic networking, and autonomy. As an example, both programs intend to incorporate off-board sensor data from highly classified national technical means. Specifically, designers hope to exploit signals intelligence from overhead collectors in real time and use this data to provide tactical cueing for UCAV weapons. This effort is both critical and challenging.

Secure and robust communications represent another key to program success. Jam-proof low probability of intercept and detection (LPI/D) communications links are vital. System developers are working to create a survivable and fault-tolerant network architecture in response to information-warfare threats.

Graceful system degradation- the ability of a system to tolerate faults and retain at least partial functionality- is also a key concern. At a minimum, the vehicles must maintain coordinated flight in the event of communications loss. Failure to fully resolve this issue in previous UAV programs has contributed to UAV accident rates 10 to 100 times higher than manned-aircraft rates.21 Onboard prognostics and health management will be essential to achieving high-confidence fault anticipation and isolation. Similarly, within the mission-control system, fault detection and localization will become key issues.

Finally, within the mission-control system, integration of advanced cognitive aids presents a major challenge. Creating intelligent onboard decision aids to enhance the operator’s situational awareness will be a fundamental requisite if developers are to achieve multiple-vehicle control by a single operator in a dynamic mission environment. Such intelligent autonomy is highly desirable because it avoids the necessity of streaming video and corresponding high-bandwidth requirements.

In solving these technical challenges, designers must devise solutions that permit inter- operability of UCAV operations with manned aircraft. In the case of the UCAV-N, the requirement to develop a ship-suitable design increases the complexity of the task. The technology appears feasible at this early stage, but a myriad of technical details and an unknown number of unidentified challenges remain unresolved.


Accurately projecting the cost of an operational UCAV system is difficult. Both the Air Force and Navy UCAV demonstration projects are still relatively immature and include many unknowns. Cost estimates based on manned-aircraft programs are unlikely to yield satisfactory results based on differences in the design approach and operating concepts. By the end of phase three- risk reduction and operational evaluation- however, Air Force UCAV program officials hope to develop life-cycle cost models that will bound acquisition as well as operations-and-support costs within an 80 percent cost-confidence band.22 The UCAV program’s affordability goal is to achieve a recurring unit-flyaway cost of one-third that of an Air Force joint strike fighter- about $10–12 million- and a 20-year operations-and-support cost of 25 percent that of an F-16 Block 50. Similarly, UCAV-N program officials hope to achieve a unit-cost goal of one-third that of a Navy joint strike fighter- about $11- 15 million- and a 20-year operations-and-support cost of one-half that of an F/A-18C.

At present, cost estimates are imprecise and, in the case of the UCAV-N, proprietary. However, one can draw several conclusions, based upon previous manned and unmanned aircraft programs. First, avionics will represent a significant portion of total vehicle cost. As a result, UCAV unit cost will be particularly sensitive to user requirements for sensor-suite (primarily radar and electronic support measures [ESM] equipment) capability. Accommodation of a surveillance requirement is likely to be a significant cost driver since it will require a more robust radar capability than that required for SEAD and strike missions. Second, DOD’s acceptance of UCAVs will be predicated largely on reductions in total operating costs over those of alternative systems. Contributors to these costs include training, maintenance, logistics, and long-term support. Program officials believe that total operating costs of the UCAV and UCAV-N will be far below those of manned platforms, in part because of their simulator-based operator-training concept. Simulator training would significantly reduce the number of training flights required, yielding significant savings through reductions in costly maintenance work hours and consumables such as fuel, tires, and spare parts.

Procurement Quantity

As is true for any weapon, UCAV and UCAV-N acquisition quantities will be largely a function of their perceived operational effectiveness, survivability, and affordability as compared to alternative systems. Determination of a prudent fleet size requires effects-based analysis, including detailed examination of lethality against anticipated targets and survivability issues such as threat capabilities, threat density, and frequency of engagement. With regard to UCAV and UCAV-N, the present fidelity of performance projections is insufficient to support a production or fleet-sizing decision. However, program officials are generating an array of cost estimates based on sizing excursions of fewer than 300 aircraft of each type.

If the vehicles enter production, one approach entails initially fielding a small fleet of UCAVs and UCAV-Ns, perhaps 10-20 of each, thereby providing users with a limited operational SEAD capability while enabling them to refine requirements and operational concepts. Lessons learned could be incorporated in subsequent block development. This approach resembles the one planned for the Global Hawk program.


If an operationally effective UCAV can be fielded affordably, many people believe it could serve as one of the key building blocks of military transformation. Compared to other power-projection systems, UCAVs have the potential to reduce total ownership costs substantially and perhaps offer one method of easing the impending funding challenges faced by the services in replacing their aging equipment fleets. Additionally, removing humans from a vehicle that maintains the stealth and precision of manned systems could expand power-projection options available to political and military leaders. These characteristics are well suited to combating the growing antiaccess threat posed by rapidly proliferating, advanced surface-to-air and surface-to-surface weapons.

UCAV prospects appear promising, but feasibility, operational effectiveness, and affordability remain unknown. Several critical system attributes, such as adaptive autonomy as well as secure, robust, and networked communications, remain areas of high risk and need resolution. Both the UCAV ATD and the UCAV-N ATD will explore these issues in detail. By the end of the demonstrations, program officials hope to bound these unknowns sufficiently to allow a low-risk entry into a formal EMD effort. However, we cannot yet precisely quantify the cost and schedule risks associated with fielding an operational system. Until we resolve these outstanding issues, any resource and force-structure decisions predicated upon fielding an operational UCAV fleet would be premature.


1. Development of unmanned aircraft began with the “Kettering Bug” in World War I. From 1971 to 1979, DOD attempted several UCAV development projects in the form of the Ryan BGM-34A/B/C. Budget constraints and system-capability shortfalls led to termination of these efforts.

2. DOD news briefing, Gen Henry H. Shelton, 19 December 1998, on-line, Internet, 7 March 2002, available from http:// "http://www.defenselink.mil/news/Dec1998/t12201998_t1219coh.html" .

3. Additional information on DOD standoff weapons is available in Christopher Bolkcom and Bert Cooper’s Missiles for Standoff Attack: Air-Launched Air-to-Surface Munitions Programs, CRS Report RL30552 (Washington, D.C.: Congressional Research Service, 9 May 2000).

4. In this case, design margin refers to the additional load-bearing capability required above the design’s load limit to prevent structural failure. DARPA program officials are designing both the Air Force and the Navy UCAV, subsequently discussed, to a design limit of 125 percent.

5. Lt Gen Michael C. Short, USAF, retired, “Lessons Learned from Allied Force and Implications for the QDR [Quadrennial Defense Review],” lecture, DFI International Aerospace Power Seminar Series, Washington, D.C., 14 November 2000.

6. Management and funding responsibilities will pass from DARPA to the Air Force, beginning in fiscal year 2003. The terms DEAD, destructive SEAD, lethal SEAD, and SEAD are sometimes used interchangeably within DOD. In UCAV ATD parlance, SEAD encompasses both preemptive and reactive DEAD.

7. “Unmanned Combat Air Vehicle Advanced Technology Demonstration White Paper,” final draft (Saint Louis, Mo.: Boeing Corporation, 7 December 2000).

8. Ibid.

9. Frank Bokulich, “TRW Builds PTO [Power Takeoff] for F124 Turbofan,” Aerospace Engineering, June 2000, on-line, Internet, available from http://www.sae.org/aeromag/techupdate_6-00/ 09.htm.

10. LOCAAS is an advanced-development program that intended to develop a technology base for future low-cost laser radar (LADAR) sensor submunitions. As currently envisioned, LOCAAS incorporates an autonomously powered maneuvering airframe with a LADAR sensor and a multimode warhead. The submunition is optimized to perform broad-area search, identification, and destruction of a range of ground, mobile, and fixed targets.

11. “Unmanned Combat Air Vehicle Advanced Technology Demonstration White Paper.”

12. Ibid.

13. Department of Defense Report on Unmanned Advanced Capability Combat Aircraft and Ground Combat Vehicles (Washington, D.C.: Department of Defense, March 2001).

14. “Unmanned Combat Air Vehicle Advanced Technology Demonstration White Paper.”

15. Ibid.

16. Department of Defense Report on Unmanned Advanced Capability Combat Aircraft and Ground Combat Vehicles.

17. As in the case of the UCAV ATD, UCAV-N ATD program officials use the term SEAD to encompass both preemptive and reactive DEAD. Briefing, John Kinzer, deputy program manager, UCAV-N ATD, Office of Naval Research, to American Institute of Aeronautics and Astronautics 2000 Missile Sciences Conference, subject: UCAV-N, 9 November 2000.

18. Ibid.

19. Geoff S. Fein, “Naval UCAV Development Program Progressing in Early Stages,” Inside the Navy 14, no. 2 (15 January 2001).

20. Department of Defense Report on Unmanned Advanced Capability Combat Aircraft and Ground Combat Vehicles.

21. Jefferson Morris, “Despite Rosy Future, UAVs Still Have Some Growing Up to Do, Report Says,” Aerospace Daily, 27 April 2001.

22. “Unmanned Combat Air Vehicle Advanced Technology Demonstration White Paper.”


Col Robert E. Chapman II (USAFA; MS, Embry-Riddle Aeronautical University) is chief of the Saudi Arabia Division, Regional Affairs Directorate, Office of the Deputy Undersecretary of the Air Force for International Affairs, Pentagon, Washington, D.C. He has previously served as a National Defense Fellow, Congressional Research Service; commander of the 33d Operations Support Squadron, Eglin AFB, Florida; and deputy chief of the Senate Liaison Office and F-22 program element monitor, Office of the Secretary of the Air Force, Pentagon, Washington, D.C. Colonel Chapman is a graduate of Squadron Officer School, Air Command and Staff College, and Air War College.


The conclusions and opinions expressed in this document are those of the author cultivated in the freedom of expression, academic environment of Air University. They do not reflect the official position of the U.S. Government, Department of Defense, the United States Air Force or the Air University.

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