Swiss aircraft manufacturer Pilatus wants to bridge what it sees as a gap in military pilot training with its new "top secret" turboprop trainer, the PC-21.
The new aircraft - which could be offered by candidates in the UK's £15 billion ($21.2 billion) Military Flying Training System (MFTS) privatisation competition - is being designed to take new pilots from basic flight skills into arenas now served only by jet trainers such as the BAE Systems Hawk and Northrop Grumman T-38 Talon.
"We wondered just how far you could stretch a turboprop into that market," says Kevin Smith, Pilatus' managing director for strategic projects and a former Royal Air Force fast-jet pilot. "Our assessment of the market is telling us that the requirements for manipulative skills in pilot training are diminishing because the front-line aircraft are becoming increasingly simple to fly, but the requirement for management skills is increasing massively. When you make that sort of assessment, you ask yourself, what does speed matter?"
The answer, Smith says, is "it does matter, but in a much more limited part of the flying training envelope".
Already a major presence in the trainer field with its PC-7, PC 7 MkII and PC-9turboprops, Pilatus was ready to move on to a new technical level to create what Smith says is "an absolutely clean sheet of paper" aircraft. Once completed, the PC-21 will boast innovations suitable for preparing new pilots for future fighter aircraft that are under development.
Among the innovations are:
A sophisticated avionics suite that can match the aircraft's training capability with the skills required for specific front-line fighters; a canopy, propeller and airframe capable of surviving bird strikes that would prove catastrophic to today's trainers; the capability to fly a navigation exercise at 300kt (555km/h) instead of the usual turboprop speeds of 210-240kt; higher wing loadings that will give turn rates more representative of jet training.
A proof-of-concept aircraft was built from a modified Pilatus PC-7 MkII, with a large engine and shortened wings. Aerodynamic devices were added to the wing to allow high roll rates and provide more jet-like handling. The success of the experimental aircraft, which flew in May (Flight International, 26 June - 2 July) convinced Pilatus it was on the right track to a newly defined market niche.
"We found that the turboprop could be stretched right the way through to take roughly 60-70% of the traditional jet training syllabus," Smith says. "We decided to combine the efficiencies of a turboprop with very sophisticated avionics in an aircraft that exceeds the current range of jet trainers in terms of its ability to train a pilot as a manager. So we're sitting in a segment which is very different to that of the normal flying training aircraft market."
Assembly of the first PC-21 prototype began during the last few months under the heavy secrecy that has so far shrouded the project. The wing structure and rear fuselage are just about completed. The structure is frozen, Smith says, adding that the aircraft has undergone wind- and spin-tunnel tests. Pilatus is now at the stage of integrating systems into the aircraft.
The long-term nature of the ultimate MFTS contract, which industry expects to run for 25 years with a five-year option, dictates an extraordinarily deliberate pace to turn out and show off a product worthy of the job. Under a private finance initiative (PFI) such as MFTS, the contractor bears all risk and responsibility for students receiving the required flying training hours. This involves not only the production and supply of the aircraft, but also spares support and service provision.
"To do that, we're going to make sure the aircraft is as reliable as we can possibly get it. That means we're going to spend more money during the development phase, and more time putting reliability and maintainability into the aircraft than we would do normally," Smith says.
No rush
"We're in no hurry to roll out a prototype, and we don't want to be quick to market now because we know the market is actually a 30-year service provision. If the aircraft is unreliable, it is going to cost us a lot of money over its life. So we're spending more money and more time on making sure this thing is not going to break in service."
The PC-21's Hartzell propeller has five scimitar-shaped blades made of carbonfibre/titanium, the third material Pilatus tested. The first, aluminium, led to problems with shaft bending, "causing us a reduction of life on the engine. Then we went to carbonfibre, which was great, but the stress profiles were unpredictable; it was difficult to test to see whether they would hold up or not," Smith continues.
The new avionics suite incorporates a mission computer developed by Computing Devices and software from Ultra Electronics' Datel Defence. The suite is a source of particular pride to Pilatus. "We have an incredibly powerful avionics system, which is based on open architecture computers," Smith says.
The PC-21 software can be altered and installed "very quickly to match the training capability of the aircraft with the skill requirement for the front line". Since the student pilots will not know, at that point, what specific aircraft they will move on to, the software's flexibility and ability to be rewritten quickly will be especially crucial so that a broad set of training requirements can be emulated.
Fighter weapons
"We have the ability to simulate the weapons loads of frontline fighters so, for instance, if you're flying a [Boeing] F/A-18, we can simulate the symbology and delivery profile that you need to train an F/A-18 pilot," Smith says. He adds: "Our aircraft will be very simple to configure or to flick between different aircraft types."
Thinking even further ahead, Pilatus has modularised the avionics to maximise its potential - possibly in other aircraft. "We are very much looking to offer the avionics system to jet manufacturers to enable them to put it into their jets. The student could then transfer from the PC-21 to the jet and stays in the same cockpit environment," he says.
"That's key," he continues, "because what you're then doing is considerably reducing 'zero value training'. If you hand over a student who has already worked inside a full mission system and keep him in the same cockpit, all you're doing is employing the expensive time on the jet in areas where only the jet will do. And that is the big difference."
Pilatus acknowledges that "tentative" discussions have been held with different jet manufacturers about possible alliances but Smith emphasises that no agreements have been made. "If we were to enter into an alliance that saw us jointly develop some aspects of the cockpit, obviously that would help Pilatus, although we are quite well down the line with the cockpit."
Refined software
One avenue such an alliance could take would be to jointly refine the software. "It may well be that some of our software will not actually reside in the PC-21; it would only go into the jet. We're into doing things that make sense, not just using technology for technology's sake," Smith says.
The amount of glass in the PC-21 is more comparable to the Joint Strike Fighter than to Eurofighter, he continues. ThePC-21 has no analogue instruments at all, but instead features "three big screens with huge mean time between failures", providing "a massive cost advantage", Smith says.
The larger 1,190kW (1,600hp) Pratt & Whitney Canada PT6A-68B engine that will power the PC-21 will admittedly soak up more fuel - and more money - than the 700kW engine on earlier Pilatus trainers. Smith, however, is confident that the added reliability of systems being installed on the PC-21 will lower life cycle costs to the extent that the savings will compensate for the extra fuel.
Despite recent reports from outside Pilatus that the PC-21 would be unveiled later this year, Smith will say only that the aircraft will be rolled out in time to ensure that it is certified for launch customer delivery. "We have the ability to press the programme and get the aircraft out in a reasonably short amount of time. I will not do that unless there is a good reason," Smith says. "I'd rather keep the development going and have a really nice whole life cost profile than have it just-in-time for the customers."
Source: Flight International
