PAUL LEWIS / FORT WORTH & MESA
Plans for the US Army's Apache and Comanche helicopters have been in a spin
Planning for the future shape and composition of the US Army's attack and scout helicopter fleet has proved a fickle business in recent years because of shifting budgets and protracted development schedules. The latest volte face calls for the combat-proven Boeing AH-64D Apache Longbow to remain the army's principal heavy hitter for a further 25 years, with the Boeing Sikorsky RAH-66 Comanche providing its eyes and ears on the battlefield.
The Comanche programme has now gone full circle. The RAH-66 dates back to the mid-1980s and the US Army's LHX requirement for an armed reconnaissance machine, when it was envisaged to build 2,096 machines at $8.9 million apiece. This was then cut to 1,292 helicopters and later, in a move to shore up the requirement, it was repositioned as successor to the Apache. Last year the programme was restructured for a fifth time and a Defense Acquisition Board (DAB) review halved the planned purchase to just 650 helicopters.
"Comanche was really designed to be a reconnaissance vehicle and then it became armed reconnaissance and then a light attack vehicle," says Chuck Allen, Boeing Sikorsky RAH-66 programme director. "I think by design and direction of the secretary of the army, we're getting back to reconnaissance and saying we'll never be the type of heavy-attack, tank-killing platform that Apache is. It was not designed to do it."
The money cut from production has gone into development. As a result, the engineering and manufacturing development budget has more than doubled from $3.2 billion to $6.5 billion to cover work though to the planned Block 3 version due to be deployed in 2012. The initial operational capability date for the first of 73 Block 1 machines has been pushed back from the end of 2006 to September 2009. This will be followed by 106 Block 2 machines, starting in 2011, and finally Block 3.
To ensure the programme adheres to this latest revised schedule, the Boeing Sikorsky team and the US Army have instigated an earn-value system to track progress closely and quickly highlight any potential delays.
The programme is now in the final throes of critical design review of the complete air vehicle system, with the exception of the Longbow fire-control radar (FCR) and low observable design features, such as airframe chines and covers for the rotor cuff attachments. A shortage of funds has delayed this until next year.
Production of the first aft tailrotor fan shroud has begun at Boeing's Philadelphia plant, and work on the forward fuselage will start in August at Sikorsky's Bridgeport factory, which will also be the site of final assembly. The programme still faces a number of critical challenges, including the need to cut weight to achieve a growth margin of at least 10% on the specified empty weight of the heavier Block 3 version. Reducing the machine's projected $32 million price tag is another major goal, made more difficult by the fact that the cost of weight loss averages $1 million per 0.5kg (1lb) saved.
US Army RAH-66 programme manager Bob Birmingham views the Comanche as ultimately a good fit for the Apache, particularly once the army deploys its planned new common missile, which promises to provide twice the stand-off range of the 8km (4nm)-class Lockheed Martin AGM-114 Hellfire anti-tank missile. "Comanche low observable signature will allow it to get in close and send back targeting information to Apache, which will be able to carry 12-14 missiles and reach targets at longer range," says Birmingham.
The army continues to press for the full 819 RAH-66s it says are needed to equip the future Objective Force. In the meantime, plans are moving ahead to further upgrade the Longbow Apache to a new Block 3 configuration, which Boeing believes will help see the machine through to 2030. As part of its RAH-66 review last October, the DAB diverted $600 million in funding earmarked for Comanche in the years 2006-9 into the Apache upgrade.
This leaves the army $700 million short of fully funding the Block 3 upgrade planned for 284 older Block 1 AH-64Ds over about five years. The critical fiscal year for funding is 2005, with the army still looking for about $50 million in development seed money. Boeing hopes to begin work on the first machine at its Mesa, Arizona, plant by October 2007. This leaves a 14-month gap in the line from the time the last of 501 Block 1-2 AH-64Ds is delivered in July 2006.
"If we don't get funding in 2005, we get into an even bigger gap than 14 months and we can't guarantee we can close it," warns Brad Rounding, Boeing Apache Longbow manager business development. The company hopes to fill the hole mainly through foreign military sales, with major campaigns under way in Spain and Taiwan. Boeing has not totally given up on putting some or all of the remaining 240 AH-64As through the Apache Longbow remanufacturing process, and many have cascaded down to the Army National Guard. Short of Congress allocating extra funds, this seems an increasingly remote possibility.
The Block 3 upgrade is primarily designed to ensure the Apache Longbow is compatible with the Objective Force being designed around the Future Combat Systems (FCS). For this purpose, the rotorcraft will leverage off systems already in development for the Comanche as well as help to mature technology for the new helicopter. "In many ways we'll be reducing the risk for their programme," says Larry Plaister, Boeing Apache modernisation manager.
Plugging Apache into the army's network-centric force of the future will be the Cluster 1 Joint Tactical Radio System (JTRS). In May 2005, the AH-64D will be the first helicopter to demonstrate the airborne element of the new software-programmable communications system and will be one of the first platforms for the system in 2008, when it is installed for the initial Lot 11 Block 3 machines.
As well as integrating into a single system, Apache's legacy radios, such as SINCGARS, Have Quick and ARC-220, along with Link 16 and the Enhanced Position Location Reporting System now on Block 2, JTRS will provide much greater throughput thanks to its Wideband Networking Waveform (WNW). "This is really the backbone for future data communications," says Jon Rogers, programme manager, Apache modernisation programmes. "It opens the door to networked sensors, shooter and command elements."
The Comanche programme office has been asked to look at accelerating the introduction of WNW, which is an unfunded Block 4 item. Providing it can start work in 2005 and the FCS programme can provide the extra $150 million needed for integration, Boeing Sikorsky says the system could be fielded on the Block 2 version of RAH-66.
Need for processing power
The addition of systems such as JTRS and Cognitive Decision Aids, formerly known as the Rotorcraft Pilot's Associate, has driven the need for ever greater processing power and the move towards open system architecture (OSA). Apart from reducing weight and support costs, OSA provides a building block for further capabilities. An addition to the Apache's mission will be level 4 control of unmanned air vehicles to allow crews to control and exploit off-board data.
Apache has previously conducted a teaming demonstration with a Northrop Grumman/Israel Aircraft Industries Hunter unmanned air vehicle using a wing-mounted C-band radio, and a more complex exercise is being planned for next year in South Korea. Boeing claims that in the future it should take only 1h to reconfigure an Apache with a UAV tactical control datalink, which entails the installation of a mast-mounted directional antenna, a modem in the avionics bay and RF antenna and receiver.
Level 4 UAV control has also been made a requirement for Comanche, but the programme office is leaving the pioneering work to Apache. "The Comanche guys want us to get a UAV capability as soon as possible," says Col Ralph Palotta, US Army Apache programme manager, "so that a TCDL is demonstrated and developed and they know they are heading in the right direction, which will save them money, or a significant amount of money if it proves to be the wrong direction."
Already in the development pipeline and running ahead of Block 3 is the retrofit to the AH-64A and AH-64D of the Lockheed Martin Arrowhead Modernised Targeting Acquisition and Designation Sight/Pilot Night Vision Systems (M-TADS/PNVS). The new system's main improvement is a second-generation forward-looking infrared (FLIR) imager for extended-range positive target identification, and second similar 8- 12µm pilotage FLIR providing higher resolution imagery for low-level nap-of-the-earth flying. Arrowhead also has an image intensification TV and the option to add a second, third-generation 3-5µm FLIR to the TADS for longer range. The army appears to have neither the funds nor the inclination to go for the latter mid-wave system, which it says does not have a wide enough field of view for piloting or clarity in smoke, unlike a long-wave system.
M-TADS/PNVS draws heavily on technology being developed by Lockheed Martin for the Comanche's Electro Optical Sensor System (EOSS). Like Arrowhead, both the lower Electro Optical Target Acquisition Designation System (EOTADS) and the upper Night Vision Pilotage System (NVPS) use a second-generation FLIR with Standard Advanced Dewar Assembly I integrated IR detector array/cooler. While Apache relies on a monocle helmet-mounted display, the RAH-66's NVPS and image-intensified TV are displayed on a binocular helmet.
The main external difference with EOSS is the low observable design of the nose-mounted turret. EOTADS includes an aided target detection mode, which will be a growth option for Arrowhead. Image fusion of the M-TADS FLIR and image-intensified TV is also planned for Lot 12 of Block 3 Apache Longbow onwards, while later versions of Comanche call for fusion of the FLIR and the Longbow FCR to automatically identify and prioritise targets.
Cross leveraging
There is also a high degree of cross-leveraging between the Longbow radar being developed for Comanche and FCR improvements planned for Block 3 Apache. The RAH-66 radar will be repackaged into a low observable mast-mounted housing, which compared with the Apache Longbow will provide a 30dB reduction in signature and weigh half as much. The Block 3 upgrade to Longbow will provide extended range, a littoral mode for target classification and faster processing by adopting the same radar electronic unit as is planned for the RAH-66.
The list of other improvements planned for Block 3 is fairly long and includes efforts to address the helicopter's operational and support costs. These include the General Electric T700-701D engine common with the Sikorsky Black Hawk, a new composite four-blade main rotor with a redesigned swept tip, a 3,400shp (2,530kW) improved durability gearbox. Other planned additions include a new dual-mode laser, the BAE Systems ALQ-212 Suite of Integrated Infrared Countermeasures, embedded diagnostics and improved maintenance manuals. Plans to fit a new fly-by-wire flight-control system have proved too costly and have been deferred, possibly to a follow-on Block 4 Apache upgrade.
The future of Block 4, which could include a new 3,000shp engine, new composite airframe structures and even directed energy weapons, hinges on the development of Comanche, on the capability of systems such as the Unmanned Combat Armed Rotorcraft, and on whether there is scope for a joint programme, with the US Marine Corps looking eventually to replace its Bell AH-1Zs.
"Maybe one day Comanche can grow and then you can have a common reconnaissance and attack helicopter fleet," says Palotta. "In the meantime, you have to continue with the Apache programme and in another five years, we'll look at Apache and where Comanche is and if it can grow, and then make a decision on another Block or if Comanche can do the job."
Source: Flight International
