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Aviation History
2003
2003 - 1810.PDF
Cover story CLEAN SHEET Pilatus believes its PC-21 turboprop is a new breed of basic trainer capable of blurring the boundaries between the training phases STEWART PENNEY / STANS Pilatus has just begun the third of four PC-21 flight-test phases and is aiming to certificate its newest turboprop basic trainer at the end of next year. The PC-21 has been flying since 1 July 2002 and, by the end of June, Pilatus had concluded the second of four phases in the flight-test programme, the stage being used for envelope expansion and "proof of design" work, demonstrating the feasibility of a high-performance turboprop. Phase 3 will "tune" the aircraft for its training role, while phase 4, to begin in the second quar ter of next year, will focus on certification. By the end of June the aircraft had com pleted 160h in 135 flights. Initially, certification will be to civil visual flight rules (VFR), but will be extended by mid-2005 to instrument flight rules (IFR). Pilatus had only planned VFR clearance, but the substantial changes in civil airspace management now mean it is appropriate to clear the PC-21 for IFR from day one. The PC-21 is the latest in a long line of Pilatus trainers. The Stans, eastern Switzerland-based company has sold more than 520 PC-7/PC-7MkIIs and 262 PC-9s, the latter also being the basis for the Raytheon T-6 Texan, winner of the US Joint Primary Aircraft Training System (JPATS) competition. Around 780 T-6s are expected to be ordered by the US forces. Despite the continuing sales of the PC-7/9, Pilatus managing director strategic projects Kevin Smith says the company elected to start its next product with a clean sheet. "We did look at a jet as well as the high-end turboprop," he says. Pilatus also built a high-performance proof-of- concept (PoC) aircraft - a PC-7MkII with the wingspan reduced by 2m (6.6ft) and spoilers added to increase the roll rate. Engine power was also more than doubled, from 750shp (560kW) to l,600shp. These changes gave the PoC aircraft a "Euro- fighter-like roll rate and very fast accelera tion to 200kt [370km/h]", says Smith. The PC-21 roll rate is 1807s using the spoilers. These also allow shorter span ailerons, which means the flaps are large enough to reduce stall speed to 80kt. The ailerons are still powerful enough to con trol the aircraft if the spoiler system is inoperative. Bill Tyndall, PC-21 project pilot, says the pilot does not notice the spoilers in the air. Aileron buffet caused by the spoilers was an issue with the PoC aircraft, but "it's not an issue now", Tyndall says. Bruno Cervia, engineering director new aircraft projects, says the spoilers only deploy after 5° of aileron has been applied. Tyndall adds that this eliminates any over-control around the mid-stick position. The PoC aircraft also removed risk from the high-performance turboprop concept, says Smith. It first flew in November 1997 "We're small so we have to stay ahead. We can't be a 'me too' company, we have to be out in front" KEVIN SMITH, PILATUS and had completed 21 Oh by December last year when its test programme ended. The PoC aircraft was used to test PC-21 software in the air before the latter flew and was instrumental in clearing the new aircraft for first flight soon after roll-out, says Smith. The combination of the PoC tests and market studies led Pilatus to the conclu sion that it had to be an innovator or leave the market, says Smith. This provided the impetus for a November 1998 decision to fund development of a new - rather than derivative - turboprop trainer, at the time known as the PC-XX. Unlike many aircraft development pro grammes, the PC-21 is self-financed by priv ately owned Pilatus, says Smith. The pro gramme is budgeted at SFr200 million ($150 million). Smith says: "We write off the dev elopment costs on an annual basis against profit. There is no goodwill charge either." This amortisation of development funds against existing products such as JPATS licence fees and the PC-12 utility aircraft meant that in 2002 Pilatus reported profits of SFr25 million on sales of SFr481 million. Profit would have been SFr66 million with out the R&D spending. "We spent SFr41 million on R&D. We're small so we have to stay ahead. We can't be a 'me-too' company, we have to be out front," says Smith. The PC-21 will improve training effi ciency "through the intelligent use of tech nology, not using technology for technol ogy's sake", says Smith. The PC-21 is designed to meet a specification so tech nology is used "where it gives substantial and tangible benefit". Training efficiency As it is cheaper to operate a turboprop than a jet, training efficiency is boosted by using the former for more of the syllabus. If mis sion management is a key part of pilot train ing, then the turboprop should be equipped with suitable avionics. It can then be used for handling and systems management training while the jet trainer is used for advanced training, says Smith, noting that the Swiss air force has retired its relatively new BAE Systems Hawks and now uses two- seat Northrop F-5s for high-energy manoeu vring training and other work outside the PC-7's performance envelope. There is now a fundamental question - where does the jet replace the turboprop, if at all, in the syllabus? These requirements, driven by cost and the changing nature of combat-aircraft operation, require new thinking in air forces and aircraft manufac turers, says Smith. PC-21 design drivers include low through-life costs, coupled with "driving up" user value. Acquisition and life-cycle costs must not exceed Pilatus's turboprop benchmark. As a result, the PC-21 is faster, 32 15-21 JULY 2003 FLIGHT INTERNATIONAL www.fliqhtinternational.com
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