Dassault's fly-by-wire Falcon 7X long-range business jet is a ground-breaking design manufactured in a radically new way. But can it outsell its North American rivals?
Timing is everything when it comes to launching a new aircraft. Not only must the market conditions be right, but the manufacturer must be ready. Available technology, internal resources and the desire to replace or complement existing products are among the many factors that must be satisfied to minimise the risk inherent in launching a major new programme.
For Dassault, the announcement at the 2001 Paris air show that it was to go ahead with the all-new Falcon 7X long-range business jet ended years of speculation about its plans for the top end of the market. The existing Falcon 900EX trijet and the twin-engined Falcon 2000EX have held the fort admirably and continue to sell well. But competition from North America, with Gulfstream pushing its G450 and G500/G550, and Bombardier with the Global 5000 and Global Express, meant Europe's only major business-jet manufacturer would have to come up with an answer.
Dassault has so far amassed more than 55 orders for the new Falcon – the best sales performance at this stage of the programme of any of its aircraft and a clear indication that the company has got the timing as well as the offering right.
The offering is radical, to say the least. Not only has Dassault taken a revolutionary approach to the design, manufacture and support of the Falcon 7X, it has made the aircraft the platform from which all of its future business jets will spring. "The Falcon 7X represents the success of the radical transformation Dassault has been through," said Dassault Aviation chairman and chief executive Charles Edelstenne at the roll-out on 15 February.
The 7X, which made its maiden flight on 5 May, is the largest, longest-range Falcon to come out of the Dassault stable, seating up to 16 passengers in a cabin 20% bigger than that of the Falcon 900EX, with four more windows and many comfort-improving changes. Its 10,500km (5,700nm) range, while less than that of either the Global Express or the G550, is nevertheless sufficient to reach all major US West Coast cities from Paris, with Tokyo reachable to the east.
Olivier Villa, Dassault senior vice-president, civil aircraft, says the last 5% of range "is needed by only a very few customers – we find most prefer a break halfway through a very long flight to go shopping or change crews".
The launch of the Falcon 7X presented an ideal opportunity for Dassault to use two of its major assets – the Catia three-dimensional computer-aided design system developed by sister company Dassault Systèmes, and a fly-by-wire (FBW) flight-control system. FBW has been a feature of Dassault combat aircraft for several years, but this is the first time it has been incorporated into a business jet. Together, the above systems have allowed Dassault to optimise the design of the 7X as never before (see P93 and P97).
Other Falcon 7X innovations include a completely new wing; carbonfibre-reinforced plastic fin; four curved instead of six flat windshields; a 35% larger horizontal stabiliser (which remains all-composite) ; new Pratt & Whitney Canada PW307A engines; increased cabin pressurisation, to the equivalent of 6,000ft (1,830m) altitude instead of 8,000ft; and a new trailing-link main landing gear from Messier-Dowty.
Also, Dassault has worked hard on reducing cabin noise to significantly less than that in the 900EX, without substantially increasing weight. Another first is the provision for a crew rest area for flights longer than 12h.
"Our choice was to work on finding the maximum improvements, but only where they were cost-effective," says Villa. "Twenty years ago, technology didn't win customers, so efficiencies weren't the driving factor in business jet design. Now that fuel accounts for 40% of direct operating costs and taxes are based on weight, technology has become a major issue. Today, we have to be able to tell our customers they're getting the most comfortable and most efficient aircraft, along with high resale value."
The philosophy with the 7X was to incorporate technologies that would yield the most efficiencies without entering risk areas. Using Dassault's own Catia system for the "paperless" design of an aircraft was a non-issue. At a stroke, this eliminated an entire stage in the manufacturing process – the need for an engineering model – or prototype. "We've made a huge step forward in the industry," says Edelstenne. "This is the first aircraft ever designed and built in an entirely virtual environment. We've started an industrial revolution that will take us through the century."
The "revolution" is illustrated by one astonishing statistic: assembly of the first Falcon 7X took half the time it would have taken for a Falcon 900. "We expect this to be reduced still further as we get into production," says Robert de Rocquigny, Dassault Falcon division vice-president for industrial operations. "Not only that, but the 7X was launched as a full production aircraft from day one. Previously, changes have been incorporated as production experience has been gained, which meant changing part numbers, and differences between all the early aircraft. Now they are all identical from the start, which saves a huge amount of time and resources."
Digital flight control
The use of a fully digital FBW flight-control system was also virtually risk-free because Dassault has incorporated it in all its military aircraft since the original Mirage 2000. In the 7X it contributes not only to improving safety by providing flight-envelope protection, but makes it possible to optimise the design of the new wing. Falcon 7X pilots will also enjoy the replacement of the main control column with sidestick controllers, releasing space in front of them for a slide-out table.
In terms of fuselage structure, the Falcon 7X remains little different from its Falcon 900 forebear. It is the same diameter – 2.34m – but 3m longer, providing an extra 1.9m internal space. Windows are located about 40mm higher to improve visibility and have 40% more area, but keep the same width to fit between the fuselage frames, which retain the same spacing as in the Falcon 2000 and 900 series.
The main manufacturing change is that, instead of being constructed in vertically sliced sections, the centre fuselage section is assembled in top and bottom halves, while the nose and rear sections are constructed as complete units. "This was more efficient because the top half is built from aluminium panels, whereas the bottom half contains the fuel tanks and is more complex," says Villa. The change results from "years of testing aimed at simplifying construction processes", he adds. Minor changes have also been wrought to accommodate the increase in cabin pressurisation.
The top fuselage section is built by EADS Socata, with Dassault responsible for the lower half. The complete nose section is built by Dassault at its Argenteuil factory, and the complex rear section by Latécoère in Toulouse. The nose is built vertically and requires no assembly jig because the component parts need no adjustment to fit together. The same is true of the wing box. "Now, because everything fits perfectly from the beginning, we can build the box in less than a month, whereas it took months before," says de Rocquigny.
The Falcon 7X wing also benefits from the use of Catia-based manufacturing software to design the creep-forming tools used to shape the upper wing planks, manufactured at the Saclin plant. This is the first time Dassault has introduced creep forming of a major component. The panels are integrally milled complete with stringers to minimise internal stresses and are mounted vertically in the milling machines to reduce the time to install and remove the billets.
It is more than 30 years since Dassault designed a new business-jet wing from scratch, the Falcon 900 and 2000 wings having been derived from that of the Falcon 50 – one of the most efficient wings around at the time. The incredible power of modern supercomputers now allows the entire airflow over the wing to be visualised and understood – in all three dimensions.
The results have been tested in low- and high-speed windtunnels in France and the Netherlands, more than satisfying Dassault's exacting requirements for efficient high-transonic performance coupled with good low-speed capability. Testing has shown, for example, that at Mach 0.85 the Falcon 7X has a 15% improvement in lift-to-drag ratio over the 900EX at M0.80.
The decision to remain with an all-metal wing rather than move to composites was "a close call", says Villa. He adds that, although Dassault already builds all-composite wings for its Rafale multirole fighter, "the realities of a combat aircraft are very different from those of a high-performance business jet. In the end it came down to a simple fact. We can get more fuel into a metal wing, and we have new high-speed machining tools which keep manufacturing costs significantly lower than for composites."
The Falcon 7X wing looks, and is, big. It has 44% more area than that of the Falcon 900EX, with inboard sweep increased to 34°, and to 30° for the outboard section, against 29° and 25° respectively for the 900EX. The 7X will climb directly to an altitude of 41,000ft (12,500m) and will cruise at 49,000ft on longer flights, with a maximum altitude of 51,000ft. Low-speed performance will be the same as for the smaller Falcon 900EX – landing at 104kt (190km/h) and requiring just 715m of runway (at sea level) with eight passengers.
At its maximum range, Falcon 7X passengers will be spending almost 13h aboard the aircraft, so Dassault has made a major effort to improve interior comfort, with particular emphasis on reducing noise.
As with the Falcon 900, the cabin is split into forward, main and aft sections, measuring 2.03m, 5.61m and 2.33m in length, respectively, against 1.54m, 4.82m and 2.13m for the 900. The aft toilet is also slightly larger and there is a new forward toilet, so that for the first time there is the possibility of separating the rear and/or main cabins totally from the forward section.
Seating (including divans) has to comply with the latest 16g crash-resistance criteria and every possible cabin configuration has to be dynamically tested to that level – a significant task for a business-jet manufacturer offering several different cabin configurations.
A third crewmember seat is provided as standard, which can swivel through 180°, and all three crew seats now recline to 137° (against 120°). A crew rest area is an option on the 7X, although fitting it into the aircraft has been "quite a challenge", admits R...mi Bachelet, director of aircraft specifications and design. US Federal Aviation Administration regulations call for a crew rest area on flights exceeding 12h, "and that means a sleeping volume of at least 1m3 [35ft3] with adjacent free space", he says.
To accommodate this, Dassault has relocated the main galley to the left-hand side, losing 0.55m of main cabin length and one window frame. Negotiations are under way with the FAA to allow a reclining seat to be used for crew resting instead of a dedicated area, "although we will still offer a rest area if customers want it", he adds. So far, only one customer has specified a crew rest area, however.
Reduced noise levels
After seven years of research into materials, damping technology and noise transfer paths using the latest finite-element analysis techniques, Dassault says it will achieve not only a 4dB SIL reduction in sound levels compared with the Falcon 900EX (in logarithmic terms about 50%), but also a 100kg (220lb) weight saving on materials.
"This took a huge effort," says Oldrati. "In the past we would have had to use far more damping material to achieve the same kind of noise reduction." Much of the work was carried out together with Dassault's Little Rock completion centre in Arkansas, USA, with the inevitable help of the virtual design system.
Working with Rockwell Collins, Dassault has also designed a new all-digital cabin management system that includes high-quality audio and video channels and a global communications system, using a Firewire databus delivering up to 800Mbytes/s, again saving weight.
The first ground test of a complete Falcon 7X took place on 1 February, marking the beginning of an extensive ground and flight-test programme, culminating in European and US certification and first deliveries in late 2006. Flight testing will involve three production aircraft, which will build around 1,200h of flying time by the third quarter of 2006. A fourth airframe has begun static testing and will be taken to 1.5 times limit load and will accumulate around 40,000 flight cycles, or twice the expected airframe lifetime.
Testing has taken place throughout the programme to date, however, with unprecedented emphasis on the relationship between the fly-by-wire flight-control system, the EASy flightdeck and aircraft performance. The work centres on two simulators at St Cloud: the Falcon simulation bench for testing flight-control laws and the Falcon global bench for equipment – hydraulics, electrics and so on. At first both simulators were used independently, but at the end of last year they were linked, enabling software glitches to be ironed out long before the first flight.
The emphasis is now on production, with the initial build rate set at three aircraft a month. This is due to rise as more customers come on board. "We'll decide whether to increase the rate in the next few months," says Oldrati.
At the 7X roll-out on 15 February, guests were treated to a spectacular display of imagery in which virtual three-dimensional images of the 7X were projected onto the real aircraft, enabling visualisation of the internal systems and the passenger cabin, complete with virtual figures. It was a powerful reminder of the state-of-the art in aircraft manufacture, and of Dassault's leadership in it.
Source: Flight International