Unmanned aerial vehicles (UAVs) are remotely piloted or self-piloted aircraft that can carry cameras, sensors, communications equipment, or other payloads. The Department of Defense has used UAVs in military operations since the 1950s because they can provide reconnaissance, surveillance, and intelligence of enemy forces without risking the lives of an aircrew. In recent years, interest in the many capabilities of UAVs has been growing among the armed services. At the same time, the services have been having difficulty actually acquiring and deploying the UAVs they have tried to develop. As a result, many of those development programs have been cancelled (see Summary Table 1). The Department of Defense (DoD) hopes to do better with the four UAVs that are now under development or in initial production: Predator, Darkstar, Global Hawk, and Outrider.
 

In this paper, the Congressional Budget Office (CBO) examines DoD's unmanned aerial vehicle programs, reviewing their missions, requirements, and development process. It also focuses on the strengths and weaknesses of the Advanced Concept Technology Demonstration (ACTD) process being used to develop them. Criticisms of the new unmanned aerial vehicles have led some Members of Congress to question whether reasonable alternatives exist to DoD's plans for acquiring and using UAVs. This paper examines five options for the various UAV programs. Those alternatives illustrate other potential configurations of the future UAV force--each of which would have advantages and disadvantages that would differ from those of the current combination of programs.
 

PROMISE AND PROBLEMS IN DoD'S UAV PROGRAMS

Unmanned aerial vehicles make up a small part of the defense budget (DoD currently spends about $600 million a year on all UAV acquisition programs--less than 1 percent of its acquisition budget). Nevertheless, they hold great promise. Military thinkers who contend that warfare is becoming more information-based believe that UAVs can play a key role by providing their users with sustained, nearly instantaneous video and radar images of an area without putting human lives at risk. At the tactical level--the local area of operations--that is a capability that battalion and brigade commanders have not had before. At the longer-range, strategic level, UAVs have some advantages over reconnaissance satellites, such as being able to watch one area for an extended period of time. (Eventually, unmanned aerial vehicles may also be used in combat operations, such as the suppression of enemy air defenses and strike missions, but those developments are still years from realization.)

Because the different military services have various imagery needs at various levels, DoD plans to field a family of UAV systems. The only one currently deployed with U.S. troops is Pioneer, which the Navy and Marine Corps use for a variety of tactical operations, including surveying potential targets and assessing damage from naval missiles and gunfire. Pioneer, which is now 12 years old, is considered outmoded and is due to be retired in 2003. That date may be pushed back a few years, however, while a successor system is developed.

The system that is next-farthest along is Predator, a medium-altitude UAV that has finished its development phase and entered low-rate initial production. Predator is an Air Force system designed to meet the reconnaissance needs of the theater commander in a major regional conflict. The Army, however, would also like its corps and division commanders to be able to use Predator in such conflicts.

The three newest UAVs--Darkstar, Global Hawk, and Outrider--are still at the development stage. Darkstar and Global Hawk, which are being developed together, are both high-altitude UAVs that would be used (in different ways) by theater commanders and national command staff for reconnaissance and surveillance. Outrider, in contrast, is a tactical UAV geared toward brigade and task-force commanders.

In reviewing those unmanned aerial vehicle programs, CBO has identified three issues of concern. Two of those issues relate to the tactical UAVs that the services would put into the field. The third relates to the high-altitude UAVs.

First, Outrider (the tactical UAV under development) may not be suitable for all of its intended missions. Although it is being developed as a joint program for the Army, Navy, and Marine Corps, Outrider will not have several attributes that are important for a Navy or Marine system operating from ships: vertical take-off and landing capability and an engine that can run on heavy fuel such as jet or diesel fuel. (It should be noted that the technical objectives of the Outrider program included a heavy-fuel engine, which was subsequently scrapped, but did not include vertical take-off and landing capability.)

Second, the manner in which the Army is planning to fulfill its corps- and division-level UAV requirements during a regional conflict may not prove feasible. The Army intends to rely on the Predators being bought and operated by the Air Force (at least as of this writing). However, Predator will receive its assignments from the theater commander; thus, the needs of Army field commanders for information that UAVs are intended to provide are not likely to be met if other missions receive higher priority.

Third, there may be overlaps in the capability provided by Predator, Global Hawk, and Darkstar. By various performance measures, such as speed, operating altitude, payload, and range, Darkstar falls between the other two (see Summary Table 2). But Darkstar is intended to be more survivable than either of them because it will have stealth characteristics. However, it is not clear whether a substantial number of stealthy unmanned aerial vehicles are necessary. If not, Predator and Global Hawk might be able to perform many of Darkstar's intended missions.
 

DEVELOPING UNMANNED AERIAL VEHICLES WITH THE ACTD PROCESS

Developing unmanned aerial vehicles has not been easy. Technical challenges and growth of costs have led to a number of unsuccessful UAV programs. Unlike those past efforts, however, the UAVs under development today are using a different process, called Advanced Concept Technology Demonstration. ACTDs are supposed to be small-budget, low-risk demonstrations of a new technology and are usually focused on meeting a specific requirement identified by the technology's intended users. The purpose of having an ACTD program that is separate from DoD's traditional acquisition and development process is to give developers a flexible management environment in which to experiment freely with new technologies and demonstrate their utility on the battlefield to commanders.

The current UAV development programs, however, are technologically ambitious. The Outrider program and the combined Global Hawk/Darkstar program have experienced numerous problems, including delayed schedules, growing costs, and the crash of a Darkstar. Predator, by contrast, moved relatively smoothly from the ACTD stage to low-rate initial production, perhaps because its contractor had an operational predecessor to work with as well as experience in integrating the many components that make up a working UAV system. Outrider, Global Hawk, and Darkstar represent much more difficult development projects. The troubles they have experienced are not atypical of acquisition programs, but those troubles come as a disappointment to people who expected ACTDs to be affordable and relatively quick demonstrations of proven technology.
 

ILLUSTRATIVE OPTIONS FOR DoD'S UAV PROGRAMS

The Congressional Budget Office has constructed five options to address the concerns that have been raised about DoD's UAV development efforts or to take greater advantage of the promise that UAVs appear to hold. Each option deals with a particular problem or aspect of the way the services or the Department of Defense are planning to develop, acquire, and use UAVs. Because they address only one particular issue of the UAV programs and missions, the options are not comparable with one another. Nor do they represent all of the possible ways to improve DoD's UAV programs; there are others that CBO did not consider. Moreover, the options were designed to address specific problems, not to generate savings.

Because many of the UAVs discussed in this paper are still in the ACTD phase and DoD has not yet committed to buying them in quantity, these options cannot be compared with an overall Administration plan. Decisions about acquisition must wait until the end of the UAVs' development and demonstration process. In the absence of concrete plans by the services or DoD to purchase particular UAVs in specific quantities, CBO compared its options--in terms of both cost and capability--with its assumption of what the services or DoD will eventually buy, based on information they provided. Furthermore, that comparison is predicated on the assumption that the UAVs now under development--Darkstar, Global Hawk, and Outrider--will all be ultimately successful and DoD will buy and deploy them.

CBO's options vary widely in their potential costs or savings (see Summary Table 3). The total for each option represents acquisition costs as well as operating and support costs over the assumed 15-year life of the UAVs. Estimates of operating and support costs should be treated with considerable caution, however. Those costs are difficult to estimate for systems that have not yet finished their development and that the services have not had much experience with.
 

Option I: Cancel Outrider or Make It Solely an Army System

The first option focuses on DoD's highest priority for unmanned aerial vehicles: giving the Army's brigade commanders a UAV capability. The option would accomplish that in either of two ways, both of which are alternatives to trying to fulfill Army, Navy, and Marine Corps UAV requirements with Outrider. Outrider has suffered a number of technical problems during its development process, including excess weight, inability to meet the Navy's requirements for take-off and landing distances, and a delay in the development of a diesel engine for the air vehicle until after the ACTD. Furthermore, by design Outrider will not be a vertical take-off and landing UAV, which would be far more suitable for shipboard operations. Consequently, both alternatives under Option I would separate the Army's UAV requirements from those of the Navy and Marine Corps.

Option IA would cancel the Outrider program. In lieu of that system, the Army would use Hunter--which was developed in the mid-1990s and terminated after the production of 56 air vehicles--to fulfill its brigade-level UAV requirements. For their part, the Navy and Marine Corps would buy a UAV with vertical take-off and landing capability and a heavy-fuel engine. (The Navy has been looking at several such systems.) This option would save about $80 million in acquisition costs compared with buying Outrider for all three services, but it would increase costs by a total of about $10 million when 15-year operating and support costs are included.

The primary advantages of Option IA are that it would give Army brigades a more capable UAV system in a shorter amount of time than the Outrider program would, and it would give the Navy and Marine Corps a UAV system better suited to coastal warfare. The disadvantages are that Hunter requires substantially more transport aircraft than Outrider to deploy, and the replacements purchased for UAVs lost through attrition will probably be more expensive with Hunter than with Outrider because Hunter has a larger and more capable air vehicle.

Option IB attempts to address the same problems as Option IA but in a different way: by favoring the Army at the expense of the Navy and Marine Corps. Despite its problems, Outrider appears capable of meeting the Army's brigade-level requirements; thus, Option IB would buy that system solely for the Army. The Navy and Marine Corps would continue to rely on Pioneer for their UAV requirements. This option would save around $140 million in acquisition and operating and support costs compared with buying Outrider for all three services. The savings stem mainly from not buying a replacement for Pioneer.

The advantage of Option IB is that the Army would get the UAV capability that it clearly wants. The disadvantage is that the Navy and Marines would have to continue relying on an old UAV system that requires a great deal of maintenance.

Option II: Use Hunter to Meet the Army's Division and Corps UAV Requirements

Option II is designed to address the problems that might arise if the Army relies on Predators controlled by the Air Force to meet its division and corps UAV requirements. After Hunter was terminated in January 1996, the Army was left without a system to carry out its division and corps UAV missions. The Army proposes relying on the Air Force's Predator. But the Air Force plans to buy only 12 Predator systems, and about half that number would probably deploy in the event of a regional conflict. The Air Force has stated that although it is willing to use Predator to support division and corps commanders, higher priorities could be set by the theater commander or the national command authority that could require most, if not all, of the Predator assets. If the Army sent two corps and seven divisions to a regional conflict--as it did in the Gulf War--it seems unlikely that the average division commander would get a prompt response to his request for a Predator to perform a reconnaissance mission. One possible solution to that problem is to give each division and corps its own UAV capability using the Hunter systems the Army has in storage.

Option II would provide a Hunter system of four air vehicles, two ground control stations, and support equipment to every division and a system of six air vehicles, three ground control stations, and support equipment to every corps. In addition, the Air Force would continue to procure Predator for theaterwide use. This option would cost $250 million more for acquisition than the Army's plan to rely on Air Force Predators (which would cost it nothing). Including operating and support costs for 15 years, the option's price tag would total $750 million.

The principal advantage of Option II is that the Army's corps and divisions would get their own UAV systems. The disadvantages are the cost and the additional logistics required to deploy and maintain those Hunter systems in the field. The Air Force's Predators would deploy to a regional conflict regardless of how the Army plans to fulfill its corps and division requirements. Thus, the logistics involved in getting the Hunter systems to a theater would represent an additional burden over what the Army would require today.

Option III: Buy Tilt-Rotor UAVs and Reduce the Army's Planned Comanche Helicopter Force

Could the Army benefit by deploying even more UAVs than it now plans? That is a difficult question to answer, but the Army Vice Chief of Staff did describe UAVs as a "major combat multiplier" after some exercises in which they played a prominent role. If more UAVs are deployed in the Army force structure, should they come at the expense of other assets, such as reconnaissance helicopters, or should they be in addition to them? As part of the development process for the Comanche reconnaissance helicopter, the Army was directed to analyze the "trade-offs" between the Comanche and unmanned aerial vehicles. While the Army is studying that issue, CBO has developed an option that would substitute tilt-rotor UAVs for many of the helicopters in the Army's cavalry aviation units. This option would save around $3.8 billion in acquisition costs and $700 million in 15-year operating and support costs.

The principal drawback of Option III is that the UAVs substituted into Army units in place of Comanches would not be armed. Thus, this option would sacrifice substantial combat capability. Aside from the money it would save, the advantage of this option is that in some ways the tilt-rotor UAVs are more capable reconnaissance platforms than the Comanche helicopters. They are about 15 percent faster and can watch an area five times longer before needing refueling. However, their line-of-sight communications link limits their radius of action to about 200 kilometers, whereas Comanches can travel much farther. However, UAVs are useful for more hazardous missions because they do not risk the lives of an aircrew.

Option IV: Use Global Hawk UAVs to Substitute for the Reduction of JSTARS

Option IV would provide additional Global Hawk UAVs to supplement the Joint Surveillance Target Attack Radar System (JSTARS) fleet. JSTARS is a joint Army/Air Force reconnaissance system that combines a powerful multimode ground-surveillance radar with command-and-control systems on board a 707 aircraft. The purpose of JSTARS is to detect mobile and stationary targets on the ground and transmit their locations to ground commanders and combat aircraft. DoD had planned to buy 19 such systems to provide continuous coverage of two theaters of combat simultaneously. The recent Quadrennial Defense Review, however, proposed reducing that planned purchase to 13 aircraft (plus one for testing).

In the Quadrennial Defense Review report, DoD argued that a fleet of 13 JSTARS aircraft would be able provide the round-the-clock coverage needed in a major theater war. In the event of a second war, some of the aircraft would have to be redeployed to the second theater, possibly opening gaps in coverage. The Department of Defense plans to "explore the potential for supplementing radar coverage of enemy force movements from long-endurance unmanned aerial vehicles."⁽¹⁾ CBO's Option IV reflects that idea.

This option would supplement the reconnaissance capability of the reduced JSTARS fleet by buying some additional Global Hawks to support the JSTARS mission. The option would cost almost $500 million more in acquisition costs and $700 million in 15-year operating and support costs than the Air Force plans to spend on either the Global Hawk or JSTARS program. But in return for that additional cost the Air Force would get additional capability. In particular, because Global Hawk would not put an aircrew in jeopardy, it could be deployed far deeper into enemy territory than the JSTARS aircraft.

Option V: End Darkstar After the ACTD and Rely on Other Systems

CBO's last option would end production of Darkstar with the three air vehicles left over from the Advanced Concept Technology Demonstration. It seeks to address Congressional concerns about apparent overlaps in the unmanned aerial vehicle programs. Darkstar is a high-altitude UAV that is designed to have low-observable (stealthy) characteristics. It is intended to carry out a particular mission: collecting imagery over highly defended targets before an enemy's air defenses have been suppressed. In addition, because of its stealthy characteristics, it is likely to be useful in supporting special-operations forces.

Other than stealth, Darkstar is expected to be a less capable UAV than Global Hawk but more capable (except for endurance) than Predator (see Summary Table 2). The Defense Airborne Reconnaissance Office and the Air Force have described Global Hawk as a highly capable but moderately survivable UAV, whereas Darkstar is a highly survivable but moderately capable UAV. The chief advantage of buying Darkstar, therefore, is to buy stealthy reconnaissance capability.

Option V would save $600 million in acquisition costs and another $400 million in 15 years of operation and support. In a sense, that is the price DoD and the Air Force appear willing to pay for stealth in an unmanned aerial vehicle. The advantage of this option is that it would save money. The disadvantage is that the Air Force would have only a limited stealthy UAV capability (just three air vehicles). However, other UAVs, such as Global Hawk and Predator, may be able to perform many of Darkstar's missions, albeit at a greater risk of being shot down by enemy air defenses. Furthermore, in light of the less threatening environment that the United States faces today compared with during the Cold War, ending the Darkstar program may be an acceptable risk to take.

1. Secretary of Defense William S. Cohen, Report of the Quadrennial Defense Review (May 1997), p. 45.

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