Global Air Mobility and Persistent Airpower Operations

James Michael Snead, P.E.

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As Operation Iraqi Freedom (OIF) highlighted, timely air mobility and sustainment of US military forces continue to require attention. An article in Air Force Magazine addressing early mobility lessons-learned from OIF noted that "demand for airlift far exceeds supply, and senior USAF officers say it is time to expand the fleet. . . . Airlift forces were pressed to their limits. . . . Gen. Tommy R. Franks, commander of US Central Command, was forced to modify his original war plan to live within USAF's 'constrained' airlift fleet. . . . [According to Gen John W. Handy, commander of the joint-service US Transportation Command and the Air Force's Air Mobility Command,] 'I firmly believe we need another Mobility Requirements Study.' "1

In May 2004, the Department of Defense initiated a mobility capability study-called for in the strategic planning guidance of 2004. According to Joint Staff briefing charts, the study will "identify and quantify mobility capabilities required to meet the end-to-end, full-spectrum mobility needs for all aspects of the national military strategy.2 Also of interest, the secretary of defense's goal of being able to "deploy to a distant theater in 10 days, defeat an enemy within 30 days, and be ready for a new fight within another 30 days . . . will be used as a benchmark in the new study."3

This article proposes an approach for leveraging technological and operational innovation in global air mobility that can provide a highly flexible, time-responsive means of globally positioning and sustaining US military forces-not only on the land but also persistently in the air. This approach, embodied in the technological and operational features of an air-mobility concept known as the configu-rable air transport (CAT), offers a new alternative to the force commander for addressing the mobility, sustainment, and airpower-projection needs of twenty-first-century warfare.

The CAT is envisioned as a C-5-sized aircraft that has more than twice the unrefueled range of the C-5 and that carries an interchangeable module in lieu of the traditional fuselage. Thus-like a fighter or bomber-this aircraft can be configured for a particular mission by loading the appropriate airlift or airpower module. Depending upon the mission, the flexible CAT could carry modules for Airborne Warning and Control System (AWACS), missileer, traditional cargo, tanker, Army or Marine fire support (gunship), Navy sea patrol, emergency communications for the Department of Homeland Security, fighting forest fires, or international humanitarian relief, among others. Mission by mission, if warranted, individual aircraft in the CAT fleet could be reconfigured to respond rapidly to changing air--mobility, sustainment, and airpower-projection needs worldwide.

This mobility-system concept should prove attractive for modernizing the aging elements of the current air-transport fleet for two reasons. First, the CAT would provide a modern, global-range aircraft with standardized performance, basing, support, crew, and training that could offer, through the use of missionized modules, a modernization path for many of today's transport aircraft such as the C-5 airlifter, as well as the E-3 AWACS, KC-135 tanker, E-8C Joint Surveillance Target Attack Radar System (JSTARS), C-9 aeromedical-evacuation aircraft, and the B-52 bomber. Second, the use of missionized modules enables the introduction of new mission capabilities without reducing current ones or requiring costly and time-consuming modification of the CAT aircraft. Together, these features provide an attractive acquisition option for developing a new mobility system that would not only replace a broad range of aging aircraft as they reach the end of their economic lives, but would also continue to provide state-of-the-art warfare capabilities through the development and introduction of new or upgraded mission modules.

The article begins by examining an earlier modular aircraft-the Fairchild XC-120. Following a technical description of the CAT and its mission modules, the advantages of using these modules for transporting war materiel are addressed, with particular attention to establishing high-throughput global air bridges, prepositioning forces at regional bases, and rapidly moving air and land forces forward into bare bases. The article concludes with a description of how the multiday endurance capability inherent in such a new global-range transport, when equipped with airpower mission modules, would enable persistent airpower operations to be employed. This would provide new options for flexible and highly responsive global airpower projection similar to that proposed by the Navy in its "sea strike" and "sea basing" concepts. It would also provide new options for homeland security.

Fairchild XC-120 "Pack Plane"

In 1949, shortly after the initiation of production of the C-119 "Flying Boxcar" transport for the Air Force, that aircraft's manufacturer, Fairchild, experimented with a design variation that incorporated a detachable fuselage module (fig. 1). Called the XC-120 "pack plane," the transport aircraft lent itself to rapid reconfiguration in support of a variety of missions. One description of the XC-120 mentions that modules could deliver cargo as well as serve as shops, weather stations, emergency hospitals, and tankers.

Figure 1. Fairchild XC-120 pack plane with detachable module. Courtesy of History Office, Air Force Aeronautical Systems Center.

Figure 1. Fairchild XC-120 pack plane with detachable module. Courtesy of History Office, Air Force Aeronautical Systems Center.

The Air Force ordered production of over 1,100 C-119 aircraft but did not pursue the XC-120. Since then, other approaches for designing a modular air transport have undergone conceptual definition in the United States and overseas. Like the XC-120, these did not attract serious interest by potential government or industry customers. Instead, industry stayed with the traditional tubular fuselage and wing-tail transport design that yielded aircraft optimized for and generally dedicated to a single mission, such as passenger carriage, large-cargo transport, and so forth. Today, as the Air Force assesses future air-mobility and airpower needs and solutions, the idea of a modular transport aircraft deserves renewed investigation.

Configurable Air Transport

The CAT is a C-5-/747-class aircraft that uses a blended-wing-body (BWB) design capable of carrying one interchangeable, missionized module (fig. 2).4 The BWB concept is a modern version of the Burnelli lifting fuselage and Northrop flying-wing concepts of the 1920s, 1930s, and 1940s.5 Since the mid-1990s, the National Aeronautics and Space Administration and the commercial aircraft industry have conducted technical evaluations of BWB designs and identified their potential for signifi-cant improvements in aircraft performance and reduced empty weight.6

Figure 2. Configurable air transport and detachable module. (Prepared by Dennis Stewart and Isiah Davenport, General Dynamics, Advanced Information Systems.)

Figure 2. Configurable air transport and detachable module.  (Prepared by Dennis Stewart and Isiah Davenport, General Dynamics, Advanced Information Systems.)

Using a modified BWB for the CAT offers several advantages over traditional wing-tubular fuselage designs. In addition to having ample volume to carry the quantity of fuel needed for global range-usually 7,000 nautical miles (nm) or more-it also has sufficient volume for stowing the long landing gear required for the modular concept and for installing active self-defense systems, such as air-to-air missiles and directed-energy weapons.7 The central area of the BWB, located behind the cockpit and over the module, can accommodate approximately 100 passengers in a manner similar to the C-5 Galaxy's upper deck. Alternately, one could configure the CAT's upper deck to provide crew-rest facilities for global-range cargo-delivery missions and for the new operational concept of persistent airpower operations, discussed later. Another design advantage is that the flat lower surface of the BWB design facilitates the mating of the large mission modules. Finally, the BWB's top-mounted engines should enhance survivability, reduce noise during takeoff and landing, and enhance multimission flexibility. For instance, this engine location opens up clear lines of sight for sensors and weapons mounted on the module, providing improved flexibility to configure modules to support a broad range of electronic and force-application missions. It also may enable the CAT to conduct amphibious operations, such as combat search and rescue or at-sea replenishment, with an appropriate amphibious landing module.

The conceptual CAT configurations in this article's illustrations reflect sizing to provide the same cargo volume as the C-5 but with approximately twice the unrefueled range. As a baseline for comparison, the C-5 is capable of carrying a maximum aircraft cargo load (ACL) of 178,000 pounds (89 tons) to an unrefueled range of approximately 3,200 nm. It has a maximum peacetime takeoff weight of 769,000 pounds, a wingspan of 223 feet, and a maximum fuel capacity of 51,150 gallons (322,500 pounds).8

Drawing upon a conceptual BWB aircraft design assessed by Boeing for an 800-passenger transport, the CAT concept carries a C-5-equivalent maximum planned ACL of 178,000 pounds (89 tons) to an unrefueled range of approximately 7,000 nm. This payload would correspond to 27 463L pallets, each with an average load of approximately 6,600 pounds. These figures yield an aircraft with a maximum takeoff gross weight of about 820,000 pounds, a wingspan of 280 feet, and a maximum fuel load of about 40,000 gallons (270,000 pounds).9

The BWB-based improvement in unrefueled global range of the CAT, when carrying the same payload weight as the C-5, has significant economic and operational advantages because of the reduced need for air refuelings and en route bases. This, in turn, leads to a reduction in both mission costs and total mission assets required. For example, aerial refueling costs approximately $175,000 for every 10,000 gallons.10 For a global-deployment mission of 6,000 nm, the C-5 requires two KC-135 tankers transferring a total of 28,600 gallons.11 Using the global range of the CAT to replace just one such C-5 air-refueled mission each month yields a mission cost reduction of approximately $6 million per CAT per year-or approximately $300 million for each CAT over its expected 50-year lifetime.

The typical CAT module would measure about 150 feet in length, 30 feet in width, and 17 feet in height. Internally, the module would have a 67-feet-by-27-feet flat floor (1,809 square feet) with a clear ceiling height of approximately 12 feet. The flat floor could accommodate 27 463L cargo pallets or rolling stock, with additional cargo stowage in the nose and tail cones. An unfurnished module would have an empty weight of about 75,000 pounds. Its upper surface would mate to the lower surface of the BWB by means of an electrically powered clamping system. The module's power system, on the order of 2,500 horsepower, would power an air-cushion system providing module -mobility on the ramp and enabling the module to be positioned for mating to the CAT.12 The self-contained power system would also provide auxiliary electrical power and environmental control for the module in flight and primary power when on the ground.

The modules would come in several basic configurations. One intended for frequent use (e.g., day-to-day cargo movement; AWACS; missileer; tanker; passenger transport; and aeromedical evacuation) could be fabricated using conventional methodology for aircraft design and assembly. Such a module would likely have a useful life of 25 years or more. Those intended for the surge transport of war materiel, including modules configured to support bare-base operations, could be built using alternative manufacturing methods and materials when lower production costs and increased production rates are emphasized. The goal would be an "expendable" module design enabling the economical production of hundreds of "war-ready" modules for placement in ready storage during times of peace, while also enabling the rapid and affordable replenishment of modules expended during hostilities.

Cargo Handling and Transport

Cargo handling and transport involve the basic operations of receiving, organizing, loading, transporting, unloading, warehousing, and distributing cargo from the point of origination to the end user. Several approaches have sought to improve the throughput efficiency of this process, starting with the most obvious of increasing the speed of the transportation system. After attainment of the maximum economic cruise speeds, further improvement requires a more fundamental change in the cargo-handling process.

Land-Sea Cargo Transportation Using Standardized
Intermodal Containers

For land-sea cargo transportation, a revolutionary improvement in throughput occurred in the mid-1950s by applying an idea that originated in the late 1930s-using standardized, intermodal cargo containers for both land and sea transportation.13 This approach resulted from recognizing that loading cargo containers from trucks to ships and back to trucks was far more time efficient than the millennia-old manual handling of individual pallets, boxes, bags, vehicles, and so forth. The new containerized approach reduced the nonrevenue-generating time of both ships and trucks by lessening the time spent waiting and finally loading and unloading. Consequently, one needed fewer ships, trucks, and dockside workers for a given throughput and revenue-generating capacity. Because of today's improved material-handling automation, computerized tracking of cargo containers, permanent dockside material-handling equipment, and well-trained personnel, workers need fewer than 50 hours dockside to unload and load a 3,000-container "lift-on/lift-off" cargo vessel. Ship-utilization efficiency-the time actually spent transporting cargo and generating revenue-comes to approximately 85 percent for transpacific use.

Module Loading and Unloading from the CAT

Similarly, the CAT modular concept speeds the loading and unloading of the cargo, thus improving the overall transportation-utilization efficiency of the aircraft and minimizing the required ramp space. Examination of movies of the XC-120 module's unloading operations and a simplified visualization of detaching a module from the CAT suggest that it may be possible to drop a module in as little as 10 minutes following arrival at the designated module-release spot on the ramp. For the one-way transfer of cargo into an air base, the CAT would land, taxi, drop the module, taxi, and then take off without stopping the engines. The total time spent on the ground might amount to only 20 minutes. By way of comparison, the C-5's ground time for unloading cargo without refueling or reconfiguration is 120 minutes.14

Attaching a module to a CAT, however, will be more complex. We could use an automatic mating system on the CAT that precisely locates the module and provides guidance cues so that the pilot can accurately taxi the aircraft into position above the module. After final alignment of the module using the air-cushion system, the actual mating would take about 10 minutes since it would involve the same basic aircraft and module operations used to drop a module-only conducted in reverse.

A preliminary time allocation, consistent with the assumptions above, indicates a total CAT time on the ground of approximately 140 minutes: 10 minutes for taxiing following landing, 10 minutes to drop the module, 60 minutes to taxi and refuel the aircraft, 20 minutes to taxi and position the CAT to pick up the next module, 10 minutes to pick up a module, 20 minutes for anomaly resolution and final checks, and 10 minutes to taxi to the runway for takeoff.15 Without refueling, the total time would approach 80 minutes. If crews could refuel the aircraft and load/unload the module simultaneously by using the mobility of the modules to move them to and from the CAT during refueling, then the total ground time would also come to about 80 minutes. The C-5, for comparison, requires 500 minutes of planning ground time for unloading cargo, refueling, reconfiguring the cargo compartment, and loading cargo.16

Simple Model of a CAT Air Bridge

A first-order system-dynamics simulation of a CAT air bridge identified the number of aircraft needed, based on assumptions for flight frequency and ramp-space requirements at the aerial port of debarkation (APOD). This model simulated a global-delivery mission to a distance of 6,500 nm without air refueling or en route base stops-for example, one way from McGuire AFB, New Jersey, to Qatar in the Persian Gulf. At an assumed departure rate of three CATs per hour, 84 aircraft would establish a constant-throughput air bridge, delivering 72 modules carrying an average of 4,400 tons per day (using a planning cargo load of 61.3 tons) for an airlift capacity of 28.6 million ton-miles per day.17 Using the assumptions stated above for ground operations for nonsimultaneous unloading/loading of modules and fueling activities, one would need seven ramp parking places at the APOD to swap modules, refuel the CATs, and prepare for the return flight. The total round-trip time from departing the aerial port of embarkation (APOE) to departing for the next trip is approximately 31.5 hours. One would also need a minimum of seven ramp parking spaces at the APOE. Turning to the C-5 once again, one sees that the ideal maximum daily cargo throughput for 52 arrivals per day, assuming seven ramp parking places, carriage of the maximum ACL, no reduction for ramp-queuing inefficiencies, no loading constraints, and no en route air refueling or basing constraints, would amount to 3,200 tons.

This simple air-bridge model was applied to the movement of a 5,000-person Army brigade with 12,000 tons of materiel to a distance of 6,500 nm. A planning cargo load of 61.3 tons was assumed, as was the fact that each CAT could also carry up to 100 soldiers in the upper deck. With a 20-minute departure spacing, the 84 CATs completed the movement of personnel and cargo in approximately 95 hours from the time the first aircraft departed the continental United States (CONUS) until the last one returned and had been unloaded and refueled. With a 30-minute departure spacing, 56 CATs completed the needed 196 missions in approximately 127 hours. Focusing on the 10-day deployment goal of the aforementioned mobility-capability study, one sees that each 84-CAT air bridge would be capable of delivering 41,000 tons of war materiel or about three Army brigades.

One criticism of the comparison of air-bridge models of the CAT and C-5 points out that the cargo in the module unloaded from the CAT is not necessarily unloaded, whereas the ideal throughput for the C-5 includes unloading the cargo. This is not actually the disadvantage it appears to be. The primary objective of using modules for moving cargo is to improve utilization efficiency of the transport aircraft. Detaching the module, moving it away from the aircraft parking spaces, and then unloading it all help to ensure a high CAT-utilization efficiency by preventing difficulties in unloading cargo-engines on rolling stock that will not start, jammed cargo restraints, lack of sufficient unloading crews or equipment, and so forth-from interfering with the processing and departure of the CATs. Further, depending on available ramp space, it is not necessary to unload the modules immediately since they provide environmentally protected and controlled storage of the cargo. A ramp area of 2,500 feet by 600 feet at the APOD could store approximately 100 modules containing 6,100 tons of war materiel. Also, with appropriate training, the arriving troops (as in the above example of the Army brigade) could unload their own equipment without the need for large numbers of Air Force personnel. Additionally, the emptied modules could serve as temporary shelter until their return.

Overcoming Limitations on Fuel Availability

Like other large air transports, the CAT requires a secure and plentiful supply of fuel. In the air-bridge example cited above, if the CATs required refueling at the APOD, the daily pumping requirement would reach approximately three million gallons. To meet these needs, the base would require a substantial hydrant-fueling network and fuel-storage capacity. Since forward locations will probably not include such facilities, one approach for establishing high-throughput transport of modules into an area like this would involve flowing the CATs through a network of regional bases (described in the following section) to the APOD. (Andersen AFB, Guam-a potential regional base in a global CAT distribution network-has a fuel-storage capacity of approximately 66 million gallons.)18 The global-range capability of the CATs permits them, unlike the C-5s, to fly 3,000 nm from the regional base into the APOD and return the same distance to the base without either refueling at the APOD or air refueling en route. One could establish APODs to handle a throughput of up to 2,900 tons per day, with a planning cargo load of 61.3 tons, at forward locations that would otherwise not be available due to a lack of aircraft-fueling capacity. A continuous 3,000 nm air bridge from the regional base to and from the APOD, with 30-minute spacing, would require 28 CATs. Moving the Army brigade, for example, would require about five days to complete. Because the aircraft would not have to refuel at the APOD, they would need only three ramp parking spots to sustain this throughput.

Global Distribution Network

One could establish a network of CONUS and overseas regional bases-for example, eastern and western CONUS, Hawaii, Guam, Alaska, Diego Garcia, and western Europe-to support the rapid global delivery of CAT modules to APODs located in most locations of interest (fig. 3). The longest route length, using a great circle, comes to 5,200 nm. The unrefueled global range of the CATs would allow them to move between these bases without en route air refueling. With this operational model, including an overlay of 3,000 nm operating radii from each of the bases, CATs transporting modules would then fly from the CONUS APOE to pick up the loaded module and then to the APOD, using regional bases for fueling and crew rotation. Returning CATs would pick up empty and unneeded modules and bring them back through regional bases to CONUS terminals for reuse.

Materiel Prepositioning and Rapid Delivery

Prepositioning of materiel to support the rapid deployment of military forces has become increasingly important. The CAT modules provide a means to environmentally protect, preload, and securely store the first-entry combat forces' air-transported equipment, supplies, and forward-base facilities in the CONUS and at regional bases without using permanent ware-houses. After activation of such forces, crews could "float" the modules containing stored equipment on the modules' air cushions to the designated module-loading location on the ramp to await arrival of the CATs and initia-tion of the air bridge to the designated APOD.

Prepositioning of preloaded modules integrates well with the global unrefueled range of the CAT. The CATs' ability to fly to an unrefueled range in excess of 10,000 nm (without modules) allows the rapid repositioning of these aircraft with minimal or no demand for en route basing or air refueling. In case of an emergency, designated CATs conducting normal air-mobility missions worldwide would land at a US or allied air base, drop their modules, and refuel. Less than 90 minutes after landing, the CATs would be en route to the designated regional base, where they would pick up prepositioned modules and carry them forward to an APOD or, as discussed later, under-take airpower-projection missions.

CAT Tanker

A tanker module will allow CATs to function as strategic tankers. For mission-assuredness purposes, such a module would have twin, high-capacity refueling booms to support the refueling of large aircraft such as the B-1, B-2, C-17, and C-5, as well as other CATs. The tanker module would have an off-load capacity of approximately 200,000 pounds at an operating radius of 3,000 nm from the CONUS and regional bases (fig. 3). On a shorter-duration mission-radius of about 500 nm-additional fuel from the CAT's wing tanks could increase the off-load capacity up to approximately 350,000 pounds. The KC-135E, in comparison, has an off-load capacity of 101,200 pounds and 10,500 pounds at mission radii of 500 nm and 2,500 nm, respectively.19

Figure 3. CAT module and tanker coverage from the CONUS and regional bases

Figure 3. CAT module and tanker coverage from the CONUS and regional bases

Modules providing tanker capability can be equipped to dispense fuel while parked on the ground. With a storage capacity of approximately 35,000 gallons and a self-powered fuel-pumping system, these modules could store and dispense fuel at forward bases-an important feature since ever-more US aircraft and ground equipment use the same JP-8 fuel. Hence, CAT tankers could use the module to escort tactical aircraft to an in-theater air base and then leave the module to support local air and ground operations.

In addition to the use of tanker modules for dedicated air-refueling missions, all CATs will probably feature permanent, wing-mounted refueling systems to air-refuel fighters and unmanned aerial vehicles (UAV). Installing a lower-capacity boom on one wing and a probe-and-drogue system on the other would permit all CATs, regardless of the transport or airpower-projection mission performed, to serve as emergency en route tankers and permit airpower-projection CATs to "top off" fighter escorts.

Bare-Base Support

The forward deployment of military forces often requires the establishment of operations at bare bases-that is, air bases or commercial airports where the runways, taxiways, and ramps are usable or rapidly repairable but where the supporting capabilities, such as fuel storage and power generation, are either not available or not readily repairable. To support the deployment of military forces into these bases, the Air Force uses prepackaged, transportable bare-base kits called Basic Expeditionary Airfield Resources, assembled at the bare base by Air Force civil-engineering teams.

CAT modules provide a new approach for these kits. Instead of using tents and erectable buildings, base personnel could utilize special versions of the CAT war-ready module for shelter. We can easily visualize the establishment of initial tactical air operations at a bare base using missionized CAT modules (fig. 4). In this example, a delivery rate of up to four modules per hour reflects the circumstance that CATs would not pick up modules for the return flight and that these aircraft do not need refueling. This delivery rate yields a total timeline of approximately seven hours:

Figure 4. Bare-base buildup. (Prepared by Dennis Stewart and Isiah Davenport, General Dynamics, Advanced Information Systems.)

Figure 4. Bare-base buildup.  (Prepared by Dennis Stewart and Isiah Davenport, General Dynamics, Advanced Information Systems.)

]. Time = 0 hour. Initial security forces and base-opening civil engineers arrive via C-130s. Planned module locations have been preestablished, based upon satellite and UAV surveillance information.

. Time = +2 hours. CATs deliver three modules for air base defense, and crews move them on the modules' air cushions to defensive locations away from the ramp. Two modules contain surface-to-air missiles and Phalanx-type air defense guns, while a third contains an antimissile/aircraft laser and target-acquisition radar. Laser defenses would also protect against artillery, mortar, rocket, and similar munitions. Operating crews for these defensive systems, as well as additional Air Force civil engineering teams, fly to the bare base in the upper deck of the CATs that deliver these modules. A fourth CAT, on the ramp (fig. 4, upper right), delivers the first Army module containing more ground-defense equipment.

. Time = +3 hours. Four Army modules (fig. 4, lower left) containing up to 245 tons of equipment and 400 soldiers arrive. After they empty the modules, personnel use them for temporary quarters and protection against chemical, biologi-cal, and small-arms attack.

. Time = +5 hours. Six modules designed to support tactical air operations arrive and are placed at the far end of the ramp. Personnel erect air-supported canopies between the modules to provide shelter for conducting maintenance and weapon loading on the tactical aircraft (fig. 4, lower right). Air Force civil engineers as well as operational-support personnel arrive in the CATs that transport these modules.

. Time = +7 hours. The final four modules containing fuel, water, and munitions arrive, as do the tactical aircraft in preparation for initiating local air operations. Subsequent deliveries replenish these modules and return the empty ones for restocking.

The bare-base CAT modules would be specially designed for this application, providing nuclear, chemical, biological, environmental, acoustic, and ballistic protection for forward-deployed forces. They might also contain active self-defense capabilities, including tactical lasers. The auxiliary power system used to run the air cushion would also provide electrical power and environmental control. The configu-ration of the interior of the modules would incorporate many specialized logistical-support functions that would normally require the erection or assembly of separate facilities-air and space operations centers, secure communication facilities, crew quarters, hospitals, mess facilities, maintenance shops, small-arms arsenals, fuel-storage areas, munitions shelters, recreation facilities, and so forth. Upon completion of the mission, crews would reload the modules on the CATs for return to the CONUS for cleaning, repair, and replenishment. Many of these modules would also prove useful in -humanitarian-relief operations. A key feature of this use of CAT modules is the ability to repack and relocate them quickly. In the example above, four CATs with tanker support could relocate these modules to another base 1,000 nm distant in about 20 hours, thus providing substantial flexibility for repositioning theater air forces as the operational campaign unfolds.

Persistent Airpower Applications

In early 1929, shortly after Charles Lindbergh's famous 34-hour flight in 1927, Maj Carl Spaatz and Capt Ira Eaker of the US Army Air Corps initiated an effort to investigate long-endurance flight.20 In the Air Corps's three-engine Fokker C-2A Question Mark, they, along with Lt H. A. Halverson, Lt E. R. Quesada, and Sgt R. W. Hooe, established an initial endurance record of just over 150 hours, involving 42 air-refueling and resupply hookups. In one of many endurance efforts undertaken later that year, Dale Jackson and Forest O'Brine established a new record of 420 hours in a single-engine Curtiss Robin, increasing the record in 1930 to 647 hours in the same plane.21 Five years later, brothers Fred and Algene Key extended the record to 653 hours (27 days), again in a single-engine Curtiss Robin.22 In this 1935 record flight, the Keys completed 432 hookups to transfer fuel, oil, and supplies and flew a ground track of over 52,000 miles.

Almost 70 years later, one has trouble locating these endurance records in the history books. Contemporary planners regard the 40-hour missions of B-2s as remarkable and assume they are pushing the edge of the envelope of human and hardware endurance. Yet, clearly this is not the case. In fact, this area of potential technology exploitation can lead to the establishment of a new paradigm of persistent airpower operations in which we could fly critical military capabilities into forward air bases. Such capabilities would provide persistent deterrence or force application when land bases are unavailable/threatened or when sea-based forces have not yet arrived. With suitable onboard areas for crew rest and multiple flight crews, persistent airpower operations with CATs would begin to emulate naval operations with a corresponding influence on the types of airpower capabilities used, joint operations undertaken, and Air Force and joint doctrine executed.

In December 2002, Vice Adm Cutler Dawson and Vice Adm John Nathman of the US Navy discussed the advantages of the persistent forward projection of sea power:

Sea Strike is a vision of what we will become as well as the focus of our capability today. It is about far more than putting bombs on target, although the delivery of ordnance remains a critical function. At its heart, Sea Strike is a broad concept for naval power projection that leverages C5ISR (command, control, communications, computers, combat systems, intelligence, surveillance, and reconnaissance), precision, stealth, information, and joint strike together. It amplifies effects-based striking power through enhanced operational tempo and distant reach. It takes U.S. power to the enemy 24 hours a day, 7 days a week, creating shock and awe both immediately and persistently. Sea Strike is what it takes to win in the 21st century.23

Similarly, in January 2003, Vice Adm Charles W. Moore Jr., US Navy, and Lt Gen Edward Hanlon Jr., US Marine Corps, discussed the twenty-first-century advantages of sea basing:

Sea Basing is the core of "Sea Power 21." It is about placing at sea-to a greater extent than ever before-capabilities critical to joint and coalition operational success: offensive and defensive firepower, maneuver forces, command and control, and logistics. By doing so, it minimizes the need to build up forces and supplies ashore, reduces their vulnerability, and enhances operational mobility. It leverages advanced sensor and communications systems, precision ordnance, and weapons reach while prepositioning joint capabilities where they are immediately employable and most decisive. It exploits the operational shift in warfare from mass to precision and information, employing the 70% of the earth's surface that is covered with water as a vast maneuver area in support of the joint force.24

We could realize many of the operational advantages inherent in "sea strike" and "sea basing" through persistent airpower operations involving CATs. Operating from the network of regional bases described earlier, groups of perhaps as many as eight CATs with appropriate airpower modules could patrol designated areas within a 3,000 nm radius of the regional or CONUS base for periods of several days (fig. 5). CAT tankers operating from these same bases would air-refuel the patrolling CATs every 12 to 18 hours. These "air battle groups" would provide the ability to rapidly establish air superiority, demonstrate national resolve, support allies, and, if necessary, project airpower without the need to first establish forward land-operating bases within the theater of operations. These persistent airpower operations would emulate deep-ocean naval operations but with the advantage that the entire surface of the planet would become accessible.

Figure 5. CAT AWACS, cargo, unmanned combat air vehicle (UCAV) flying tender, and direct-fires-support module. (Prepared by Dennis Stewart and Isiah Davenport, General Dynamics, Advanced Information Systems.)

Figure 5. CAT AWACS, cargo, unmanned combat air vehicle (UCAV) flying tender, and direct-fires-support module.  (Prepared by Dennis Stewart and Isiah Davenport, General Dynamics, Advanced Information Systems.)

Such an air battle group might consist of CATs carrying the following types of modules:

. Integrated flight-operations center, AWACS, and JSTARS for battlespace situational awareness and battle-group command and control (C2).

. Airborne laser for missile defense and self-defense of air battle group.

. Standoff-attack module carrying 50 2,000-pound missiles capable of Mach 7 speed and a range of 1,000 nm for rapid, precision strike.

. Ballistic-missile-defense module carrying 40 3,000-pound air-launched antiballistic missiles for defense against theater ballistic missiles.

. Direct-fires-support module carrying twin 155 mm cannons; multiple tactical lasers; and medium-range, precision-attack munitions to provide sustained fires support for special operations forces and to defend US and allied forces, including forward bases.

. UCAV flying tender carrying two Mach 3.5 UCAVs and 400 precision-attack munitions to conduct battlespace surveillance and attack.

. CAT tankers for refueling fighter escorts.

Just as the US Navy puts its carrier battle groups to sea during times of increased threat as a show of force and to increase forces deployed forward, the air battle group offers similar possibilities for airpower. These unique CAT advantages-global unrefueled range, which enables the quick repositioning of CATs; rapid mission reconfiguration using airpower modules prepositioned at regional bases; and multiday endurance with refueling-allow the Air Force to rapidly assemble, project, and sustain airpower virtually anywhere in the world. Within 12 hours or less, if CAT air battle groups are already airborne, the Air Force could provide a first and signifi-cant response to threatening forces or could engage attacking forces with substantial, long-range, precision firepower. Within 24 to 36 hours, we could globally reposition, refit, and send forward 10s of additional CATs to sustain the initial airpower operations and link up with other arriving joint forces. CATs could become core elements of the military's "first-response" air and space force.

The CAT concept would also support homeland defense. CATs flying multiday air-patrol missions could undertake missions such as ISR, ballistic and cruise missile defense, counter smuggling detection, negation of captured airliners or ships, C2, and airborne communications. CAT modules similar to those used for forward bare-base support could be used for post attack support in areas temporarily isolated from ground access and communication. Finally, one could possibly adapt CAT tanker modules to support fighting forest, pipeline, and urban fires resulting from terrorist attack or other causes.

The CAT UCAV flying-tender module (figs. 5 and 6) highlights the flexibility in new operational approaches enabled by the CAT and its modules. In this concept, a CAT serves as the flying tender for two 15,000-pound UCAVs, rearmed and refueled by the tender module. Preliminary estimates indicate that each UCAV could carry four 250-pound precision-guided weapons to an operating radius of 750 nm at a cruise speed of Mach 3.5. Assuming the CAT orbits 300 nm outside "Red's" border, the UCAVs could strike targets and conduct surveillance up to 450 nm inside of Red. At this maximum combat radius, the UCAV would have a mission cycle time of approximately one hour. Each CAT tender and its twin UCAVs could attack eight targets each hour or approximately 200 targets per day. At closer distances, each tender's UCAVs could attack up to 24 targets per hour. The CAT's UCAV tender module would carry approximately 400 250-pound munitions-enough for 100 reloads of the UCAVs.

Figure 6. Left: a CAT's UCAV flying-tender module. Right: an in-flight UCAV rearming. (Prepared by Dennis Stewart and Isiah Davenport, General Dynamics, Advanced Information Systems.)

Figure 6. Left: a CAT's UCAV flying-tender module. Right: an in-flight UCAV rearming. (Prepared by Dennis Stewart and Isiah Davenport, General Dynamics, Advanced Information Systems.)


Figure 6. Left: a CAT's UCAV flying-tender module. Right: an in-flight UCAV rearming.  (Prepared by Dennis Stewart and Isiah Davenport, General Dynamics, Advanced Information Systems.)

The UCAVs on each tender could also conduct 50 or more ISR sweeps within the battlespace during each 24 hours to augment other air and space capabilities. Advanced communication systems, perhaps using direct-line-of-sight lasers, would link the UCAVs and the tender aircraft to provide real-time C2 of the former throughout most of the mission. Further, outbound UCAVs could relay ISR data identifying high-priority targets to the C2 CAT, which could then relay updated target lists to inbound UCAVs, thereby providing a responsive deep-strike capability.

CAT Crisis-Augmentation

The Air Force relies upon the CRAF to augment organic military-transport capabilities during times of crisis. The versatility of the CAT offers a new approach to providing crisis augmentation. A government-owned, contractor-operated fleet of CATs, notionally called Eagle Air (fig. 7) and manned by Air Force Reserve and retired aircrews, could perform the bulk of the day-to-day movement of CAT modules to support peacetime operations of the US military and humanitarian and peacekeeping operations of the US government. For one weekend a month and two weeks each year, the CATs and their Reserve crews would train with the assigned active duty air-mobility units. In times of crisis, these Eagle Air CATs could then quickly activate, integrate into their active duty units, and conduct virtually all of the air-mobility and airpower-projection missions.

Figure 7. A CRAF Eagle Air CAT loading Army rapid-deployment modules. (Prepared by Dennis Stewart and Isiah Davenport, General Dynamics, Advanced Information Systems.)

Figure 7. A CRAF Eagle Air CAT loading Army rapid-deployment modules.  (Prepared by Dennis Stewart and Isiah Davenport, General Dynamics, Advanced Information Systems.)


[We need] a future force that is defined less by size and more by mobility and swiftness, one that is easier to deploy and sustain, one that relies more heavily on stealth, precision weaponry and information technologies.

-President George W. Bush

Transforming the ability to move and sustain US military forces is, as President Bush stated, critical to preparing US military forces for the future and providing the president with the military capability needed to effectively protect and defend the United States and its allies.25 This article has attempted to respond to this need by describing how advanced aeronautical technologies, combined with an innovative modular system architecture, offer the potential to significantly increase the air mobility and sustainment of US military forces. In particular, the article has sought to show how the air mobility aspects of the secretary of defense's goal of being able to "deploy to a distant theater in 10 days, defeat an enemy within 30 days, and be ready for a new fight within another 30 days" may be achievable. Further, the article has tried to demonstrate that this modular-system architecture may provide a cost-effective means of modernizing our aging air-transport fleet with an innovative aircraft system that provides air mobility, sustainment, and airpower-projection capabilities that will significantly enhance the responsiveness and agility of US military forces well into the future.


1. John A. Tirpak, "The Squeeze on Air Mobility," Air Force Magazine 86, no. 7 (July 2003): 23, 24, 25, http://

2. Jason Sherman, "DoD Study May Pit C-17s, Fast Ships vs. Fighters," Defense News, 21 June 2004, 1.

3. Ibid., 8.

4. The CAT is one of 66 futures war-gaming concepts defined and assessed in the Air Force Technology Seminar game conducted by the Air Force Research Laboratory in 2000-2001 in partnership with the Air Force Directorate of Strategic Planning.

5. "Northrop's Flying Wing Airliner," in Glen Edwards and the Flying Wing: The Diary of a Bomber Pilot, The Warbird's Forum, November 2003, paxwing.htm.

6. "The Blended Wing Body: A Revolutionary Concept in Aircraft Design," NASA Facts Online, 24 April 2001,

7. The notional CAT design includes a landing-gear configuration derived from the design of the B-58 bomber of the late 1950s. The B-58 had a high wing-about 7.5 feet-and carried a large centerline fuel pod. Its landing-gear design used a simple structural configuration and fold mechanism that yielded an extremely light landing-gear weight fraction, despite its long length.

8. Air Force Pamphlet (AFPAM) 10-1403, Air Mobility Planning Factors, 18 December 2003, 12, table 3, http://; C-5 Galaxy Fact Sheet, http://; and C-5A/B Galaxy,

9. These estimates are based on aircraft size and performance for a large Boeing BWB conceptual aircraft. See "Boeing Blended Wing Body Large Commercial Transport," Jane's All the World's Aircraft, 14 July 2003,

10. This assumes an average air-refueling cost of $17.50 per gallon of fuel, as reported in "B-52 Re-engining, Financing Plan Endorsed," Air and Space Daily, 8 April 2003.

11. AFPAM 10-1403, Air Mobility Planning Factors, 18, table 11.

12. As an interesting point of comparison, General Motors recently showed a concept car that included a 1,000-horsepower V-16 engine.

13. This idea, originated by Malcolm McLean in 1937, was not put into practice until 1956. His Sea-Land Corporation initiated the concept of commercial, containerized cargo transport. See onthemove/exhibition/exhibition_17_2.html. In 1950 the United States Army developed a similar concept called "CONEX" that saw extensive use in Vietnam; it has led to today's military use of intermodal containers.

14. AFPAM 10-1403, Air Mobility Planning Factors, 14, table 5.

15. This scenario assumes a hydrant system for refueling with two hookups to the aircraft, each with an average flow rate of 450 gallons per minute. Onloading 30,000 gallons of fuel would take approximately 45 minutes.

16. AFPAM 10-1403, Air Mobility Planning Factors, 14, table 5.

17. For C-5 planning cargo load, see ibid., 12, table 3.

18. A1C Claudia Garcia-Strang, "Andersen to Have Largest Fuel Storage Contractor to Turn Over New Tanks Soon," PACAF News, 17 October 2002, http://www2.

19. AFPAM 10-1403, Air Mobility Planning Factors, 17, table 10.

20. "Flight of the Question Mark," USAF Museum History Gallery, postwwi/fqm.htm.

21. Capt Franklyn E. Dailey Jr., USN, retired, Socked In! Instrument Flying in Northern Latitudes, 2002, appendix A, "Aviation Events, 1929-31," flying/flywara.htm.

22. "Curtiss J-1 Robin: 'Ole Miss,' " Smithsonian National Air and Space Museum, aero/aircraft/curtiss_j1.htm.

23. Vice Adm Cutler Dawson and Vice Adm John Nathman, USN, "Sea Strike: Projecting Persistent, Responsive, and Precise Power," US Naval Institute Proceedings 128, no. 12 (December 2002), proceedings/Articles02/PROdawson12.htm.

24. Vice Adm Charles W. Moore Jr., USN, and Lt Gen Edward Hanlon Jr., USMC, "Sea Basing: Operational Independence for a New Century," US Naval Institute Proceedings 129, no. 1 (January 2003), proceedings/Articles03/PROseabasing01.htm.

25. Department of Defense, Transformation Planning Guidance, April 2003, 3, docs/transformationplanningapr03.pdf.

James Michael Snead (BSAE, University of Cincinnati; MSAE, Air Force Institute of Technology) is the lead for Agile Combat Support in the Aeronautical Systems Sector, Plans and Programs Directorate, Air Force Research Laboratory (AFRL), Wright-Patterson AFB, Ohio. He has also served as a science and technology engineer at AFRL, focusing on futures war gaming and future war-fighting concepts. Other positions at Wright-Patterson include lead structures engineer, Aeronautical Systems Center; chief flight-systems engineer/ lead structures engineer, National Air and Space Plane Joint Program Office; and project engineer, Transatmospheric Vehicle Project Office. Currently Mr. Snead is chairman of the American Institute of Aeronautics and Astronautics (AIAA) Space Logistics Technical Committee.

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