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Aviation History
2003
2003 - 1463.PDF
Technical description i ensure Aermacchi achieves its goals, safety, reliability and maintenance specialists have been integrated alongside other engi neers for the first time on an Aermacchi programme, "to ensure the requirements are embedded into the design and not bolted in at the end. It is a parallel, not series approach," says Trombetta. When M346 design work started in January 2000, it also marked the first use of an integrated project team at Aermacchi, he adds. The Italian ministry of industry is financing development of the aircraft. As a result, the company has to meet schedules and targets, which are checked annually. Aermacchi also has to repay the govern ment, which will receive money from every M346 sale. The industrial programme comprises six risk-sharing suppliers of the principal sys tems. These include Teleavio, which is responsible for the flight control system, including integration of the BAE Systems North America flight control computer; Microtecnica, providing the hydraulics; ASE, responsible for the electrical system; Martin Baker's Italian subsidiary SICAMB, providing the ejection seat; and Honeywell, teamed with Fiat, which is sup plying the powerplant. Seven partial risk-sharing partners - such as Liebherr, which is contributing the nose landing gear - nine component and subsystem suppliers and 45 vendors are also on the programme. Aircraft responsibility For the three prototype aircraft, Italian companies are responsible for 50.6% of the aircraft with US organisations contributing the second largest slice - 30.2%. This could change for production aircraft, as Aermacchi is aware it will have to meet national offset needs in future competi tions. "There are no rigid agreements with suppliers and we have the freedom to rearrange industrial participation to cope with local industrial offset requirements," says Lucchesini. The programme schedule calls for the first flight of M346 P01 at the end of November. This aircraft was due for roll out on 7 June and will now undergo exten sive ground trials. Aircraft P02 is due to fly in the late third quarter or early fourth quarter of next year, with the third proto type to follow 12 months later. Although P03 will be assembled in the experimental shop, it will be the first built to production standard. Two struc tural test articles will also be manufactured to the same standard as P03. The first pro duction M346 is due to fly in January 2007. Initial operational clearance for the aircraft is planned for late 2006, with full clearance scheduled for the following year. This timetable allows Aermacchi to meet MFTS and Eurotraining schedules, accord ing to Trombetta. Aermacchi's M346 performance predica tions include a thrust-to-weight ratio "close to one" at half fuel load, while the aircraft's sustained turn rate is "close to that of operational fighters", says Trom betta. Landing and take-off performance are better than that of existing trainers, with the landing run achieved without the requirement for a brake chute, which is "an operational cost". The low-speed performance is achieved with leading-edge flaps and double-slotted, constant chord trailing-edge flaps. Stall speed is below lOOkt (185km/h), with the high lift devices lowered. A knock-on effect of the low landing speed is that the brak ing system dissipates less energy, which increases system life. The maximum Mach operating number of Ml.2 has been verified in windtunnel tests and will be confirmed in flight tests. Trombetta says that the M346's perfor mance sits between that of today's advanced trainers and fighters, although he points out that the latter achieve much of their improved performance through use of afterburning engines. Much of the performance is due to the twin F124-200 turbofans, which as well as a high thrust-to-weight ratio also have a throttle response "representative of mod ern fighters", says Trombetta. The engines are also dressed identically, allowing any engine to be put in the left or right hand bay without requiring additional prepara tion work. The aircraft is also designed to allow ground operations with only the starboard engine running. The 207bar (3,0001b/in2) hydraulic sys tem is split, with the No 1 system supply ing the flight control system only and the No 2 supplying the flight controls and util ities. Trombetta says the system has growth potential and includes two emergency accumulators for the undercarriage. Because of the 1 x 106 catastrophic failure requirement, the aircraft will be recoverable after a double failure. The Microturbo Rubis auxiliary power unit (APU) is to be cleared for in-flight restart and will supply hydraulic power as well as energise the aircraft's bat teries. The Rubis will supply the electrical and environmental control systems, provid ing 5kW and 7kg/s (151b/s) at 4.4bar respec tively. It will be cleared for airstarts up to 20,0O0ft (6,100m). The flight control system is divided between primary and secondary controls. The former, comprising the ailerons, eleva tors and rudder, are protected even in the event of a double failure. The secondary The safety requirement "drives the architecture and functional choices of hardware and software design". ELIGIO TROMBETTA, DEPUTY PROGRAMME MANAGER controls comprise the leading and trailing edge flaps, and the dorsal-mounted air brake. The variable camber wing results from the leading edge flap being "continu ally tuned" by the flight control computer, says Trombetta. Carefree handling is a function of the air craft's aerodynamics and the flight control system's control law design. Control and stability augmentation is provided through out the flight envelope. The autopilot is also part of the flight control system. Failure modes are available for training missions "to expose the student to failure conditions", but in a real failure the system will automatically reconfigure, says Trombetta. The FCS is integrated with other systems through dual 1553B data- buses. Dual 1760 buses are used in the weapons system, while radar, electronic countermeasures stores management and forward looking infrared (FLIR) sensor information are also carried on a common bus. A basic avionics bus integrates the communications, navigations and cockpit display functions. "Quadruplex, fully digital fly-by-wire is a significant effort in the M346 development and certification programme," says Valerio Cioffi, flight control systems chief engineer. Tailoring training FBW also offers the potential to allow the training organisation to "tune" tuition, increasing the difficulty level as a trainee becomes more experienced. To maximise the M346's mission efficiency, it will be able to continue with a training mission despite a failure. If a mission is scrubbed before completion, it has to be reflown, incurring additional costs. At the heart of the FCS is a BAE North www.fliqhtinternational.com FLIGHT INTERNATIONAL 10-16 JUNE 2003 97
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