Tom Nicholson, BAE managing director Nimrod, says the initial flights are the next key development stage. "The first few flights prove so many things," he says, such as the new engine installation and the aerodynamic fundamentals. BAE has the first flight software ready and "every subsystem could be cleared for service this year, with all the functionality", he adds. BAE needs to fly around 30h a month to meet the aggressive flight-test schedule, but Nicholson says: "The amount of hours is less of a worry [because Nimrod has] longer flight times. The challenge is to do the right tests and not get too much data." Nimrod acquires a lot of data in-flight, which is recorded in the mission and maintenance systems, as well as the flight-test specific information, all of which needs assessing, along with the evaluation from the 10-man crews.
Testing the Nimrod will be undertaken by joint teams of BAE, RAF and Ministry of Defence personnel, says Simon Dennis, MoD resident project officer. Customer staff working with BAE at Warton, north-west England, include a training systems team developing the aircrew manuals and operational conversion unit (OCU) course; members of the Nimrod Operational Evaluation Unit (NOEU) working as part of the joint trials team (JTT) and who will fly as observers on some flight trials; a Nimrod field team working on the maintenance manuals and considering the support infrastructure and spares needs; and a software development tracking team which will ensure that the RAF can maintain Nimrod code once the aircraft enters service, says Dennis.
Nicholson says talks are under way to have NOEU personnel take part in flight tests so the aircraft's tactical employment can be developed as part of the programme. Defence research company Qinetiq is also providing test pilots and mission specialists from the national test centre at Boscombe Down to advise the MoD on certification as well as assess the aircraft against the requirement, says Dennis. Peter Davidson, BAE Nimrod test and evaluation manager, says there is a 50:50 split between BAE and customer crew, "which is seen as a joint, common pool to fly the trials aircraft".
Flight testing will begin at Woodford, near Manchester, and, once the aircraft is considered "robust and we are over the initial teething troubles", the testing will move to Warton, says Davidson. Flight testing from Woodford is expected to take around three months, although the aircraft will return to Woodford for major overhaul, he adds.
Davidson says the first two aircraft (PA1 and PA2) will fly later this year, with PA3 flying in the first quarter next year. These will be followed by PA4-11, which will be the first seven aircraft delivered by March 2005. Dennis says: "The first seven are delivered pretty rapidly so it will be a challenge to get the [RAF's] capability in place, to get the OCU up and running." Frontline Nimrod crew will take part in the test and evaluation and then become the core of the OCU, he says. After PA11 is delivered there will be a gap as further MR2s are taken out of service for rebuild and so that the MRA4 can be bedded down. Deliveries then begin again in early 2008.
Davidson says PA1, which will have the most extensive flight test instrumentation (FTI), will be used for basic air vehicle and general systems tests. This will include flutter and handling trials, initially with a clean wing and later with underwing weapons. Other key trials will be engine handling and intake compatibility and R-R has a dedicated FTI suite with its own workstations on board. Performance testing will last until early 2004, when natural icing trials are planned along with water-splash trials at the French test centre at Istres. Davidson says an additional, early, water-splash test is being considered in case intake water-ingestion is a problem. This will give time to develop a solution, such as adding deflectors to the nose gear, and retest the aircraft ahead of IOC. He says: "Up to mid-2004, the work is the priority for IOC and where there are high risks, such as intake water ingestion, then we will do post-IOC requirements such as air-to-air refuelling." Other post-IOC tests will be handling and performance at high all-up weights and at centre of gravity extremes. PA1's flight-test programme is expected to cover around 200 flights of 2-4h endurance, says Davidson.
PA2 will be the first MRA4 with a full mission system and will be used for systems and airframe tests, while PA3 will be a dedicated mission systems test vehicle. The two aircraft are expected to fly 160 and 140 6h sorties, respectively, says Davidson. "The large crew gives scope for flexibility on the sorties," he adds. To ensure the best use of flight time, crews will rehearse the flight-test mission on the Weapon System Integration Rig (WSIR) at Warton to ensure the systems are handled correctly in the air, says Davidson. Dennis adds that the WSIR provides a head-start on the evaluation, and some flight testing will be proving that the ground-based rigs are giving accurate results.
PA2 will be "three aircraft in one" says Davidson, as it will be used for flightdeck and environmental trials and as a back-up to PA3. Flightdeck trials will include evaluation of the two-crew concept, autopilot and autothrottle, and the cockpit avionics. Initial hot/cold trials will take place in an environment hangar in the USA, "as early as possible", before the aircraft is taken to real hot and cold conditions. As it has the full capability, PA2's third task will be to share mission system testing with PA3. This will include stores release as the aircraft is fitted with high-speed video cameras. Davidson says sonobuoy release "is a priority and will be done very early on. It's an absolute priority as it opens the way to testing the acoustics system." Release testing will begin on the ground at Warton, where BAE has dug a long drop pit as there was no facility to test releases from the Nimrod's long weapons bay. These will be followed by in-flight releases, initially of weapons-bay stores and then the underwing Harpoons.
PA3 will be dedicated to mission systems and will have a smaller FTI fit dedicated to monitoring the mission system and incorporating databus recording. Initially, the aircraft will be used for lightning strike tests at Woodford, says Davidson, before it is used to test each sensor's performance individually, before testing the MRA4 as an integrated platform. Operational testing will include two periods at the US AUTEC undersea range in the Bahamas, where the aircraft will attempt to find a Royal Navy submarine. The AUTEC trials will be part of the Operational Performance Assessment Criteria (OPAC) work, says Davidson. OPAC is designed to test the aircraft as an integrated whole in realistic operational conditions rather than against specification points.
A static-test wing has been installed in a rig at Woodford and, by the end of last month, calibration of strain gauges had started. Fatigue tests will begin in 2004 at Woodford, using a wing attached to a fuselage reclaimed from the ill-fated Nimrod AEW3 programme. Cook says BAE has 1,000h fatigue clearance to begin flight testing, while BAE has referred to Comet testing for pressurisation data and information on the tailplane and fin.
Source: Flight International
