[3.0] The E-8 Joint-STARS (2024)

v1.1.1 / 3 of 4 / 01 jun 02 / greg goebel / public domain

* The Grumman Mohawk was a major step forward in battlefield surveillance,but it was limited in range, endurance, and sensor capability. The RC-7carries much better systems, but it was designed to provide moderatecapability at moderate cost.

However, even before the RC-7 was conceived, the US Army was already workingwith the US Air Force to develop a much more powerful surveillance asset thatcould provide military commanders with a "God's eye view" of an entire battletheater. The result of this collaboration was the "Joint Surveillance &Target Acquisition Radar System (Joint-STARS)". This chapter provides ashort description of Joint-STARS.

[3.1] JOINT-STARS ORIGINS

* In the 1970s, US military interest in more sophisticated and powerfulsurveillance systems led to development work towards an advanced SAR systemnamed "Pave Mover" by the US Defense Advanced Research Projects Agency(DARPA) and the US Air Force (USAF). The Army was also considering abattlefield surveillance system based on the Sikorsky H-60 helicopter anddesignated the "Stand-Off Target Acquisition System (SOTAS)".

Costs of SOTAS soared, and the Army was forced to abandon the project.Shortly afterward, in 1982, the Army and the Air Force merged their programs,and spent the next two years combining their requirements. The result wasJoint-STARS.

Joint-STARS was intended to provide an all-weather battlefield surveillanceplatform that could detect, locate, identify, classify, track, and targetenemy assets on the battlefield, and pass this information on to US commandand attack elements on land, sea, or in the air over data links. The Armywas to obtain data from Joint-STARS through truck-mounted AN/TSQ-178 "GroundStation Modules (GSM)", which would be attached to headquarters organizationsto give ground commanders a window onto the battlefield.

Grumman's Melbourne Systems Division in Florida won the contract in 1985, andbegan development of two "E-8A" prototype Joint-STARS platforms, based on"used" Boeing 707-320C jetliners obtained from commercial operators. Initialflight of the first E-8A was in 1988, with both E-8As available foroperational test during the Gulf War in 1991, where they proved remarkablyuseful, even though they were not production-specification machines.

In the meantime, a contract was awarded for single production prototype E-8Cin 1990, which would fly in March 1994, followed by award in 1993 of a "lowrate initial production (LRIP)" contract for five E-8Cs, with deliveriesbeginning in 1995.

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[3.2] JOINT-STARS DESCRIBED

* The Boeing 707-300 series of airliners on which Joint-STARS is based is a"stretched" derivative of the original 707-100 series airliner, intended fortrans-Atlantic passenger and cargo operations. There were a number ofdifferent subvariants in the 707-300 family, including all-passengeraircraft, and aircraft that could be "quick-changed" by the users to anydesired mix of passengers and freight. The 707-300 is the most heavilyproduced of all 707 variants, with at least 545 built. The most visibleexternal feature is that all but a few early-production 707-300s lack theventral fin of most other 707 variants.

As the 707-300 is no longer in production, all Joint-STARS platforms arebased on used machines, but the Boeing 707 is a robust aircraft, theairframes have plenty of life left in them, and the "used" market for the 707is good. It is unclear if any one 707-300 subvariant is preferred forconversion to Joint-STARS configuration, though the E-8A conversions werebased on the 707-323C "quick change" subvariant.

Other aircraft platforms, including new-build 707s with modern CFM turbofanengines, Boeing 757 or 767 airliners, or the McDonnell-Douglas MD-11airliner, were considered, but the cost of new aircraft was simply too high,and basing Joint-STARS on used aircraft hopefully would reduce delays inreaching operational service. The new-build 707s had been seriouslyconsidered and in fact were to be the basis of an "E-8B" Joint-STARS, butBoeing finally shut down 707 production completely.

Some observers have suggested that the Pentagon made a foolish bargain instaying with used aircraft, producing analyses that show on a full"life-cycle" basis, the costs are not really lower, but the capability is.However, this dispute is impossible to resolve from the sidelines.

* Outside of the extensive fit of electronic systems, few changes have beenmade in the 707-300 aircraft itself. One obvious addition is aboom-refueling receptacle behind the co*ckpit, not a common fit on commercialaircraft. The co*ckpit layout remains much as it was in commercial service,with no update to modern "glass co*ckpit" standards.

Most significantly, the aircraft retains its original Pratt & Whitney JT3D-3Bturbofan engines, known as "TF33s" in military service. They are reliableand effective engines, but by modern standards noisy, dirty, and inefficient.It would be desireable to update Joint-STARS platforms to modern CFMInternational F108 turbofans, which burn cleaner and quieter, and offersubstantially more power and greater endurance, but the money doesn't seem tobe there.

* Of course, the electronics fit is something the original designers of the707-300 could have barely imagined. The interior is fitted with two rows ofdisplay and control consoles, while the fuselage prominently displays a 7.3meter (24 foot) long "canoe" fairing mounted behind the nosewheel, whichaccommodates the antenna for the Norden-built "APY-3" phased-array multi-moderadar.

The antenna mechanically tilts from side to side for elevation scanning, butazimuth scanning is performed electronically through phase-interferencetechniques. The radar system provides at least three operating modes:

• Wide-Area Surveillance / Moving Target Indicator (WAS/MTI): This is the radar system's primary operating mode. It tracks moving ground targets in a target area 512 square kilometers (200 square miles) in size. The target area can be "radar referenced", meaning it moves with the aircraft; or "ground referenced", meaning it remains fixed to one set of ground coordinates for as long as possible.

  WAS/MTI gives battle commanders a "big picture" of what's happening on the battlefield. Targets are color-coded on the operator display to targets whose nature is known; targets that have not been identified; and targets that have come to rest, as opposed to those that are still moving.

  WAS/MTI provides a number of interesting features, such as the ability to discriminate wheeled vehicles from tracked vehicles from the fact that the bottom of a track is motionless relative to the ground, while the top is moving twice as fast as the vehicle itself. A threshold can be set so that the MTI ignores vehicles moving above a certain speed, allowing the operator to focus on slow-moving tanks and not fast-moving automobiles. WAS/MTI also has a maritime mode, and has demonstrated the ability to target fast-moving helicopters.

• Sector Search Mode (SSM): SSM is essentially a "zoom" or "spotlight" mode that focuses in detail on a target area of about 30 x 30 kilometers (18 x 18 miles), with a radar revisit time of 60 seconds.
• Attack Planning Mode (APM): APM is a "high resolution" zoom for final determination of targets to attack, focusing on a 12 x 12 kilometer (7 x 7 mile) area. Revisit time is 6 seconds.
• Synthetic Aperture Radar / Fixed Target Indicator (SAR/FTI): The SAR/FTI mode is used to produce detailed photographic-quality maps of the battle area. It builds up such "mosaic" images from multiple radar sweeps.

  In SAR mode, the radar has a range of 175 kilometers (110 miles) to either side of the aircraft from operating height. During a single eight-hour sortie, a million square kilometers (386,000 square miles) can be mapped.

All reconnaissance data is stored on board and can be displayed on operatorconsoles, or dumped to a fast laser printer. Data collected over a period oftime can be displayed in a "movie" format so that a battle commander canobserve the evolution of the combat situation.

Communications to external stations is through a "Surveillance & Control DataLink (SCDL / Skittle)". The data is picked up by the truck-mounted GSMs,which have two display consoles and a laser printer, and GSM operators canaccess Joint-STARS data without intervention from the operators on board theaircraft.

The GSMs include a telescoping antenna that can be jacked up to a height of30 meters (100 feet), and tow a generator to provide power. The GSMs alsoinclude a "Global Positioning System (GPS)" receiver to allow them topinpoint their own locations using the GPS navigation satelliteconstellation. There is no real limit to the number of GSMs that can link upto Joint-STARS, though obviously bandwidth becomes a problem as the numbersof GSMs increase.

Joint-STARS is also fitted with two "Joint Tactical Information DistributionSystem (JTIDS)" datalinks, one of which is used to relay targeting and otherdata to strike aircraft, the second of which is dedicated to communicationswith an "Airborne Warning And Control Systems (AWACS)" aircraft, presumablyan E-3 Sentry, cooperating with Joint-STARS to control the battle.

In addition, the two E-8A Joint-STARS prototypes were fitted with a smallfairing on the belly just behind the wings and in front of the little SCDLantenna. This fairing housed the antenna for the "Flight Test Data Link(FTDL / Fiddle)" and, as its name implies, was intended solely fordevelopment flight test purposes.

* The E-8A prototypes were fitted with a variable number of operatorconsoles, depending on the progress of development activity, and alsoincluded at least one test console. The production E-8C includes 17 operatorconsoles, plus a "defensive systems" console. The defensive systems includewarning sensors but no active countermeasures as of yet, and certainly nodefensive armament.

The standard mission crew count is 21, and includes both Air Force and Armypersonnel. Seating is provided for takeoff and landing, and there are sixbunks and a rest area. Up to 34 crew may be taken on long-endurancemissions, with the aircraft kept in flight with mid-air refueling.

 E-8C JOINT-STARS: _____________________ _________________ _______________________ spec metric english _____________________ _________________ _______________________ wingspan 44.4 meters 145 feet 9 inches length 46.6 meters 152 feet 11 inches height 13 meters 42 feet 6 inches empty weight 77,600 kilograms 171,000 pounds max loaded weight 152,400 kilograms 336,000 pounds maximum speed 1,000 KPH 620 MPH / 540 KT service ceiling 12,800 meters 42,000 feet endurance (unrefueled) 11 hours _____________________ _________________ _______________________

[3.3] JOINT-STARS IN SERVICE

* The two E-8As were sent to Riyadh, Saudi Arabia, to participate inOPERATION DESERT STORM, the offensive to drive the Iraqis out of Kuwait. Thetwo aircraft arrived on the night of 11:12 January 1991, and were performingthe first of 49 combat sorties on 14 January, two days before the start ofthe air war. They were supported by six GSMs, and protected in the air byfighter "barrier" combat air patrols.

Although this deployment was in principle simply an operational evaluationand the aircraft were only fitted with about ten operator consoles, the twoJoint-STARS aircraft proved valuable combat assets, targeting Iraqi combatelements, particularly during their hasty and disastrous retreat from Kuwait.Joint-STARS sensor imagery mapped out the movements of Iraqi vehicles on the"Death Highway" and pinpointed them for attack. One senior USAF officercommented on the Joint-STARS service in DESERT STORM: "Moving targets didnot stay moving for long."

The formal planned Joint-STARS operational evaluation did not actually beginuntil 1995, with stateside tests leading to deployment of one of the E-8Asand the first E-8C to Germany to support OPERATION JOINT ENDEAVOR, the USpeacekeeping mission to Bosnia. The second production E-8C was also deployedlater. Joint-STARS flew missions over the Balkans from December 1995 throughMarch 1996.

This exercise was to lead to full-scale production, but results were notentirely satisfactory. The old JT3D-3B engines simply weren't powerfulenough to allow operation at specified maximum operational altitude andrequired long runways, and system reliability was not up to specification.

The first E-8C went into formal USAF operational service in June 1996, to befollowed by the second in August 1996. Full production of a total of 19operational Joint-STARS aircraft, including updates of the two E-8As to fullE-8C configuration, was authorized in September 1996.

A total of 12 E-8Cs had been delivered as of early 2002, and five more arein various stages of construction. It is unclear if the final two will bebuilt.

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[3.4] REFINEMENTS

* As Joint-STARS has gone into service, improvements have been added. Radarsystem software has been updated to provide enhanced capabilities, such asimproved target identification, and the ability to "underlay" various classesof map data on the operator displays.

Communications capabilities have been improved as well, including addition ofa new "Link 16" datalink system, a superset of JTIDS, to improvecommunications with strike aircraft; an "Improved Data Modem (IDM)" forcommunications with Army air assets, particularly AH-64 Apache gunshiphelicopters; and receivers to allow Joint-STARS to pick up intelligencenetwork broadcasts.

The 11th E-8C was the first "Block 20" aircraft, which featured twocommercial Compaq "Alpha" processors that replaced the five mil-standardprocessors fitted on the earlier "Block 10" E-8Cs. The two Alpha processorshave substantially more total processing power than the five older processorsthey replace, and are based on open architectures that are easier to expandand modify.

The Block 20 E-8C also featured new workstations, provided by Compaq; a newradar signal processor provided by General Dynamics; and a fiber-opticnetwork for system interconnection on the aircraft. The earlier Block 10E-8Cs will be brought up to Block 20 specification.

The most ambitious upgrade planned for Joint-STARS was the "Radar TechnologyInsertion Program (RTIP)", which was to provide the platform with a much morecapable radar system. However, RTIP proved to be the "thin entering wedge"for where the entire concept of US battlefield surveillance was going, andwent off in a number of directions. The status of RTIP is discussed indetail in the next chapter.

* Ground systems have been improved as well. The AN/TSQ-178 GSM was phasedout in 1999, being replaced by the more sophisticated AN/TSQ-179 "Joint-STARSCommon Ground Station (CGS)". Like the GSM, the CGS is truck-mounted andhighly mobile. The CGS has secure direct radio and satellite data links tocommunicate with Joint-STARS and other assets, and can display and processJoint-STARS data for relay to field forces.

The CGS can also obtain intelligence data from other assets, such as the RQ-1Predator and Shadow 200 UAVs; the RC-12 Guardrail; the RC-7B ARLM; the EC-135Rivet Joint SIGINT platform; the EH-60 Advanced Quick Fix ELINT helicopter;and the new sensor-laden RAH-66 Commanche scout-attack helicopter.

CGS can perform "fusion" on multiple inputs to provide better intelligenceoutput. CGS output is relayed to field units through a truck-mounted"Tactical Operations Center (TOC)". The Army plans to obtain 96 CGS systemsby 2002, and the Marine Corps plans to obtain three in the same timeframe.

A simplified "man-portable" Joint-STARS terminal, the "Joint Services WorkStation (JSWS)" is also in use with the USAF and the US Navy. The JSWSallows access to a subset of Joint-STARS data. The Army is also looking atan improved "Distributed CGS", to begin delivery in 2006, to allow uniformaccess from the level of the battlefield commander with a workstation, tothat of a squad leader with a portable computer.

* There has also been consideration of upgrading the aircraft's engines,which have inadequate power for full-gross-weight flight operation.Upgrading to CFM turbofans, which would be the technically optimum solution,is regarded as too expensive, but there has been a push towards a more modestfix: replacing the original 707 JT3D turbojets with JT8D turbofans.

This is replacing a 1950s engine with a 1960s engine, which may seem like aweak solution, but the JT8D is quieter, cleaner-burning, more fuel efficient,incrementally more powerful, and much easier to maintain than the JT3D.Refurbished JT8Ds and spares are widely available at low cost, and a JT8D canbe swapped with a JT3D with minimal aircraft modifications.

Pratt & Whitney formed a partnership with a San Antonio, Texas, based companynamed "Seven Q Seven" in the late 1990s to explore the possibilities for aJT8D upgrade for the various 707-based military platforms in service aroundthe world. The partnership led to the flight of a 707 demonstrator withthree JT3Ds and one JT8D in July 1999.

The effort went quiet for a while, but was revived when the Air Force issueda requirement for reengining their Joint-STARS aircraft. This led to theinitial flight of a 707 demonstrator with four JT8D-219 turbofans on 9 August2001. The aircraft is expected to receive FAA certification sometime in2002.

Northrop Grumman is also competing in the USAF program. The Air Forceexpects to lease the engines and award the winner a contract to performmaintenance for the duration of the lease. Modern turbofans have not beencompletely ruled out, but it is likely that cost will drive the selection tothe JT8D.

P&W / Seven Q Seven see a potential for re-engining up to 70 militarized 707swith the JT8D, and are open to the idea of re-engining commercial 707s aswell. Price of an upgrade is estimated at $20 million to $25 million USD.

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