PAUL LEWIS / MESA
Boeing's Apache attack helicopter is undergoing a thorough facelift as its market dominance is threatened by such rivals as Eurocopter's Tiger
The Boeing AH-64 Apache has largely dominated the international attack helicopter market since its 1991 Gulf War baptism of fire, racking up a succession of competitive wins in, among others places, the Netherlands, Singapore, the UK and more recently Japan. But Australia's selection last year of the Eurocopter Tiger finally marked the arrival of a new challenger. The Apache and Tiger are now fighting it out in Spain, after which the battlefield is expected to shift to the Nordic countries, with an emerging Finnish and eventual Norwegian and Swedish requirements.
Despite having first flown in 1991, the Tiger has for many years languished in second and even third place behind the Apache and older Bell AH-1 Cobra as the result of protracted development and funding delays by France and Germany. With Australia, France and Germany having collectively committed to 182 helicopters, the programme has established market credibility. Eurocopter's task now is to develop Tiger into a more robust multi-mission weapons system if it is to challenge Apache's strong market lead.
Evolution
The Apache has evolved considerably since the Hughes YAH-64 first flew in 1975. US Army deliveries of AH-64As started in 1984, the year France and Germany signed their first agreement to develop the Tiger. Boeing is now midway though rebuilding 501 machines into AH-64D Apache Longbows, with the effort focused on a sustained modernisation, both for foreign military sales and the US Army, which plans to continue flying the type for another 25 years.
Operation Anaconda in Afghanistan helped lift the cloud hanging over the Apache since the helicopter's unsatisfactory sideline performance during the 1999 Kosovo conflict. Eight AH-64As were deployed in Afghanistan and were called on to provide fire support for US Army ground units engaging with al-Qaeda and Taliban forces in the 10,000ft (3,000m) high Shahi Khot Valley. Five helicopters were hit, including two by rocket-propelled grenades, but all made it back to base - one machine flying for 30min with a dry transmission.
"The Apache is the toughest airframe we've ever built and I've got 10 pilots alive largely because we invested in a very strong airframe," says Maj Gen Richard Cody, commander of the US Army's 101st Air Assault Division. Three years ago Cody commanded the abortive Task Force Hawk Kosovo deployment to Albania and wrote a subsequent report highlighting deficiencies in AH-64 systems and crew training.
Enhancements
Many of these shortcomings are being, or will be, addressed by a Block 2 package of enhancements included in the second multiyear (MY II) purchase of 269 Apache Longbows; deliveries of the first Lot 6 helicopters began in March. Next year's Lot 7 helicopters will feature new ARC-210 radios, video recorders and provision for a 570 litre (150USgal) internal auxiliary fuel tank in the 30mm (1.2in) chain gun's ammunition bay. Next year's machines will also be equipped with new systems, weapons and display processors hooked up to a fibre-optic databus for faster speed and broader bandwidth.
The Lockheed Martin Arrowhead modernised target acquisition and designation sight/pilot night vision sensor (M-TADS/PNVS) will be added from Lot 8, addressing the need specified by the Cody report for a second-generation forward-looking infrared (FLIR) sensor. Arrowhead will significantly cut the AH-64's current $4,365/h cost of operation, of which the current TADS/PNVS is the single biggest driver. Lots 8-10, the last of which is due to be delivered in 2006 completing MY II, include a digital map, improved video transmit/receive capability and helmet-mounted displays.
Another major cost-cutter is the progressive recapitalisation of the US Army's fleet of 741 Apaches, including 240 AH-64As not currently funded for modernisation, which are being passed on to the Army National Guard. The comprehensive list of upgrades includes the overhaul of the Apache's auxiliary power unit (APU), transmission, landing gear, gun turret and main rotor head. Another large package of selected recapitalisation items is being been validated by the Sandia National Laboratories.
Boeing, looking to 2006 and beyond, is lobbying for money on two fronts - for an MY III upgrade of the remaining AH-64As and a third follow-on block of improvements. "When you look at the cost of maintaining a dual fleet in terms of training, logistics and support, it costs more not to modernise than to modernise. These 240 aircraft could remain in service and save the army about $1.4 billion over 20 years," says Brad Rounding, Boeing Apache Longbow domestic business development.
Modernisation
The army is less focused on MY III than on securing funds for a Block 3 modernisation in 2004-09. The yet-to-be finalised package of enhancements would be retrofitted to the AH-64D fleet, starting with Block 1 machines in MY I Lots 1-6. "Based on the [Boeing Sikorsky RAH-66] Comanche being fielded at a rate of 62 a year, the D model is shown staying in service until 2027. You cannot let a high-technology platform like the D model sit around for another 25 years without doing something to it. The question is: what do you want to do?" says Col Ralph Pallotta, US ArmyAH-64 project manager.
The list of options has been broken into five categories and distributed to the operators for feedback. The list will then go to the army's senior leadership for a final decision. The options include:
improved target detection and acquisition - extended range fire control radar (FCR), improved radio-frequency interferometer (RFI), common Comanche processor, image and sensor fusion and Joint Tactical Radio System.
increased situational awareness and survivability - Rotorcraft Pilot Associate, unmanned air vehicle (UAV) control and improved aircraft survivability equipment (ASE).
enhanced performance and reduced operations and support cost - improved rotor, uprated General Electric T700-701C/D turboshafts and drive, Rotorcraft Open System Architecture (ROSA) and advanced flight controls.
maintenance - interactive electronic maintenance manual.
transportability - folding rotor, wing and horizontal stabiliser and collapsible antenna.
It is unlikely the army will get all the money it needs for the full menu of Block 3 items, but it is clear some have a higher priority than others. Cody, a veteran Apache pilot from the Gulf War, says: "I always want to see further than I can shoot. I want to be able to identify the target at the range of the weapon system and I want to be able to know where I am at all times, and where my partners are."
The Lockheed Martin/Northrop Grumman joint venture is working to extend the 30km (55nm) range of the Longbow FCR by around 50%, and some customers are asking for expanded target-recognition sets. The company is also offering to enhance Arrowhead by adding third-generation 3-5µm FLIR. This would give the M-TADS/PNVS a dual-band capability comprising a staring array midwave sensor for long-range and long-wave scanning array for wider field of view and better smoke penetration.
The US Army's Apache fleet is powered by T700-701Cs and older, less powerful -701s, which the army would like to upgrade to a common standard. The choice is between the 1,400kW (1,890shp) -701C, already on some machines, and the 5% more powerful -701D variant in preliminary development for the Sikorsky UH-60M. The cost difference for upgrading a -701 is marginal, with the -701C costing $350,000 and the -701D $425,000. The -701D offers lower support costs because of engine communality with the UH-60M.
The AH-64's next most expensive features are its drive and rotor systems. The army is planning a two-phase improvement to the former, initially uprating the present 2,130kW transmission to 2,535kW. Changes will include near net shape forge gears offering 25% extended life and the use of less expensive and more durable Pyrowear 53 steel. There are plans to move the auxiliary power unit (APU) driveshaft clutch from the APU to the transmission. This provides better clutch cooling and allows the APU to run for extended periods on the ground with the engines off.
Boeing and the US Army have jointly invested in the design of a new composite rotor blade compatible with the 2,535kW drive system. The main advantage is reduced manufacturing and support costs rather than performance. "The goal is a simpler blade, designed for higher structural gross weights and costing 30% less to produce. We expect to get at least twice the life out of this blade at current weights and significantly better life, even up to 19,000lb [8,630kg]," says Larry Plaster, Boeing Apache modernisation manager.
Transportability
Another army priority after the 11 September terrorist attacks is better transportability. The Apache can take 6h to dismantle and, with blade tracking, sometimes up to three days to put back in service. Cody's goal is to move six AH-64s inside a Lockheed C-5 and have the helicopters ready to fly within 2h. A folding main blade has already been developed for the UK's Westland-built Apache AH1s, while the removal time for the horizontal stabiliser has been reduced from 3h to 15min. Boeing has also found a method for removing and storing the Longbow radar on the aft engine bay, eliminating the need for bulky crates.
A major issue for Boeing is keeping pace with new processors, which are frequently obsolete and out of production by the time a helicopter is built. The long-term solution is to go to an open architecture or ROSA. This will allow processors to be swapped for new ones without the need for requalification or software updates. Block 3 could also include some initial features of the Rotorcraft Pilot's Associate (RPA) decision-aiding package already demonstrated on a modified Apache, for tasks such as flight planning, terrain following and action-on-contact pilot cues.
RPA is seen as critical to expanding Apache's interoperability with and ability to control UAVs without increasing pilot workload. As part of the Aviation Applied Technology Directorate's (AATD) planned Hunter Stand-off Killer Team advanced concept technology demonstration,AH-64Ds will team with UAV "wingmen" to improve targeting and situational awareness. "The goal is to have the system fieldable in a set of test aircraft in South Korea in two years," says Plaster.
To improve ASE, the army is trying to reinstate previously cut funding for BAE Systems' infrared countermeasures suite in Block 3, but with improvements to the Longbow radar frequency interfero-meter, the ITT ALQ-210 integrated radio frequency countermeasures suite is less of a priority. New weapon capabilities in the pipeline include long-range precision missiles like the Raytheon Loitering Attack Munition - Aviation and the proposed Low Cost Precision Kill laser-guided upgrade to the venerable 2.75in (70mm) rocket.
Adding an air-to-air missile capability is an option, but in the face of a US Congress-mandated competitive fly-off between the Raytheon Stinger and Thales Starstreak, the US Army is in no hurry to add the capability. "The army has sent a letter to Congress certified by the secretary of the army, saying we're not going to do the test because Starstreak cannot be approved by our safety authorities to be safely fired off an Apache," says Pallotta.
Beyond Block 3
Boeing has already outlined the basis fora Block 4 package of improvements, formerly referred to as AH-64X, for 2011 and beyond. The centrepiece would be an all-new 2,235kW turboshaft which AATD wants to develop under the Common Engine Programme. This in turn would require an all-new 2,980kW-class transmission, but any increase in size will exceed the available space on the Apache.
One solution which has been under study by Boeing and gear maker Derlan for a number of years is a split torque drive. This features two input pinions meshing with upper and lower face gears, producing twice as much contact area and needing no extra space. The challenge is to produce two perfectly ground and aligned face gears ensuring a perfect 50:50 split in upper and lower torque. Boeing has already produced a 2,090kW demonstration transmission, which has been run to 375kW, achieving a 48:52 split. There is now AATD funding for an RDS-21 programme to build a new set of gears and run the transmission at 140%, with the army eyeing applications beyond Apache, such as the future unmanned combat armed rotorcraft.
With the gross weights of the Apache having risen over the years, Block 4 would add a fifth composite blade. Already funded is the high performance landing gear shock strut, which increases the 13m/s crash rating from a maximum mission weight of 6,800kg to 7,950kg. Additional power will also require more strengthening of the Apache's airframe, which is the subject of a $50 million rotary-wing structure demonstration (RWSTD) by Boeing and AATD. "The goal is to develop a composite primary fuselage to replace the current structure that will be 25-30% stronger without any increase in weight or cost," says Plaster.
One of the goals of Block 4 is to strip around 250kg from the helicopter's empty weight, much of which could be realised by switching to a fly-by-wire (FBW) flight control architecture and removing many of the helicopter's heavy ballistic-tolerant mechanical controls. A triple redundant FBW system would permit the full implementation of RPA. The new advanced transmission, RWSTD and FBW taken together are projected to reduce acquisition costs by 35%, and operation and support costs by 50% on average. The bottom line, adds Plaster, is a "simpler and cheaper design".
Source: Flight International
