It’s not reinventing the wheel, just how the wheel gets put on

 - October 2, 2007, 10:41 AM

Over the past decade or so, Dassault Aviation has raised the eyebrows of some business aircraft industry analysts. Why, some asked, didn’t the French airframer follow Bombardier and Gulfstream in the charge to develop an ultra-long-range corporate jet? Why, others wondered, hasn’t Dassault matched the offerings of Cessna and Raytheon in the ever-expanding small and midsize business jet sectors? Sure, Dassault has progressively enhanced its existing Falcon family, but does it have a long-term product development plan in the executive aircraft marketplace?

The answer to these questions doesn’t betray any lack of initiative or ambition on Dassault’s part. It is simply that the group has opted to exercise its energies and capital in other avenues. And after largely keeping its efforts under wraps, Dassault is now starting to show the world just how serious it is about business aviation by heralding the arrival of its all-new Falcon 7X trijet.

The $37 million trijet, announced at the 2001 NBAA Convention, will carry eight passengers up to 5,700 nm with NBAA IFR reserves. As such, the aircraft is positioned between, at one end of the spectrum, Dassault’s existing Falcon 900EX (which can fly 4,500 nm), the Gulfstream 450 and Bombardier’s new Global 5000 and, at the other, the longer-range Global Express and Gulfstream 500/550.
According to deputy program director Vincent Oldrati, Dassault has no qualms about the 7X going up against the established long-range jets from its North American rivals because, according to its market research, G500/550 and Global Express customers hardly ever use the 6,500-nm range their big airplanes can deliver.

Flying eight passengers nonstop out of New York at Mach 0.80 (85-percent wind reliability, NBAA IFR reserves), the 7X will reach anywhere in North America, South America and Europe, as well as just about all of Russia and the Commonwealth of Independent States, most of the Middle East and about two-thirds of Africa. Its maximum operating speed is Mach 0.90 and typical cruise speeds are envisioned at Mach 0.85.

The 7X will retain the Falcon family’s low-speed performance, offering a landing speed of 104 knots. Carrying eight passengers, the new model is expected to need just 2,350 feet of runway to land (sl, ISA).

“This is more than just a new aircraft,” said Olivier Villa, Dassault Aviation’s head of civil programs. “The Falcon 7X has been a real design challenge and a chance to go back to zero.”

Building Smarter
In essence, Dassault’s goal hasn’t been to offer a new Falcon that will fly farther, faster or fuller than any other business airplane. Rather, its endeavor has been driven by the desire to fly smarter than rival jets that have reached the marketplace sooner. The company has also been determined to ensure that the 7X is built smarter through a fully digital development and production program founded on the most advanced iteration of the Catia 3-D design software from Dassault Systèmes.

When the 7X makes its anticipated international debut at the Paris Air Show next year, the world will finally have the chance to see what Dassault has been keeping up its sleeve since launching the program in fall 2001. The most striking feature will be an all-new wing, but inside the cockpit visitors will find business aviation’s first full-blown fly-by-wire flight controls, as well as the new EASy flight deck based on Honeywell’s Primus Epic avionics suite.

The 7X will also boast a new powerplant in the shape of Pratt & Whitney Canada’s 6,100-pound-thrust PW307A turbofans and a new all-composite fin box–developed by Dassault’s Biarritz plant in the southwest corner of France and providing higher strength and reduced weight.

The next few months will be critical in determining whether Dassault’s faith in the efficacy of the Catia “virtual plateau” design concept has been well founded. Dassault factories around France, as well as those of program partners, are now cutting metal, making composite structures and assembling airframe sections.

The design data, which started being released to production plants late last year, is proving to be so accurate that the pre-drilled sections are fitting together perfectly, eliminating costly redrilling and reworking. Essentially, the production engineering phase of the program has been completely banished.

By next month, the first production aircraft (there will be no prototypes) will start undergoing final assembly at Dassault’s main Mérignac factory near Bordeaux as the aircraft is prepared for a first ground run before year-end. The first flight is scheduled to occur during the second quarter of next year, and certification and first deliveries are due to be achieved “during the second half of 2006.” The design has been frozen since December.

Common Design Database Key
The key to the program’s precision is the common design database that the 7X design team established from the outset. At the peak of the design process, almost 400 engineers from Dassault and 27 partner companies (from seven countries) were working alongside each other at the airframer’s St. Cloud headquarters in the suburbs of Paris.

Once the common design database, which is accurate down to the last rivet, had been created and the design was well under way, the partners were able to move back home, continuing their work through real-time interfaces with the “virtual plateau” design. By safeguarding the integrity of the common database, the team could keep working on detailed facets of the design without compromising the precision with which everything would come together at the production phase.

Using a virtual-reality software suite at St. Cloud, Dassault and its partners have also been able to validate the entire manufacturing process, avoiding the need for a physical mockup to be made ahead of full-scale production. The team has also been able to evaluate issues such as system accessibility for maintenance.

The designers even went so far as to introduce digital mannequins modeled on the actual physical dimensions of real Dassault test pilots to test factors such as the alignment of cockpit equipment and the size and location of airframe access points.
“For the first time, absolutely everything has been included in the design database,” explained Falcon 7X design manager Jerome Camps. “The whole team can be sure that every interference [between parts] and every dimension in the design is absolutely real and accurate.”

Faster Manufacturing, Same High Quality
Dassault expects to get the same standards of production quality on the first 7X that it now has on the existing Falcon 900EX. The company has been coy about overall program savings from the use of all this 3-D design technology–perhaps because they are not yet fully quantified. However, Dassault has estimated that the greatly reduced tooling and production engineering requirements alone will probably save about 50 percent of these costs found in earlier programs.

The first central wing-box sections have been made in less than a month, compared with the “several months” required for existing Falcons. Similarly, whole lower-fuselage sections are now being produced in about three months, compared with the six-month standard cycle.

The jigs required for 7X production are much simpler than those normally required, since the airplane is built directly from the digital model rather than from the dimensions of the jigs themselves. For instance, the T12 cockpit and front fuselage sections now being assembled at Dassault’s Argenteuil factory can be simply hung vertically while technicians work on them. Similarly, greater automation and simplicity have been achieved in the milling process at the company’s Seclin plant in northern France.

At several of the Dassault parts, robots are being used for some of the manufacturing and assembly tasks, and these machines receive their instructions directly from the digital design. The 3-D models and other Dassault Systèmes software are used to verify the dimensions of parts produced. The robot riveting process is already proving to be about 30 percent faster than the same process for the Falcon 2000.

Virtual reality may be in the ascendancy these days at Dassault, but the 7X will have a real iron bird. By the end of next month, Dassault will start integrating all the 7X systems on this unit at St. Cloud. This iron bird will be used mainly for checking hydraulic and electrical controls, which will be coupled to flight controls using a mathematical model. Essentially, the purpose of the iron bird for the 7X program is to verify the integrity of the interface between the digital flight controls and the hydraulic, electrical and backup systems. With artificial power sources for all three engines, the iron bird can be run at full operating speeds.

The first complete 7X wing is due to be delivered from Marignas to nearby Mérignac on September 15, in time for first ground runs by year-end. Wind-tunnel tests were conducted between April and September last year, largely confirming aerodynamic expectations and allowing for some design calculations to be modified.

The PW307A engine has logged more than 80 flight hours on a testbed aircraft since last July. At press time, the fully integrated powerplant system was set to take to the air. Including ground testing, the new turbofan has logged in excess of 1,200 hours.

State-of-the-art Technology
The main driver of the 7X’s performance is a brand-new wing, 44 percent larger than that on the Falcon 900EX at 761 sq ft and enabling a lift/drag ratio that is 30 percent more aerodynamically efficient. According to Oldrati, the new wing has been optimized for transonic performance and for the effects of aeroelasticity (wing-bending). The 7X will be able to climb directly to an initial altitude of 41,000 feet and will generally cruise at 49,000 feet on longer flights. It is expected to operate up to 51,000 feet and its maximum speed will be Mach 0.90.

The other main feature that will set the 7X apart from an operational point of view is its fly-by-wire (FBW) controls. Dassault is the only business aircraft manufacturer that also makes high-performance fighters, and it has funneled this experience into an FBW system that–combined with Honeywell’s intuitive EASy flight deck–promises to reduce pilot workload greatly, especially in safety-critical situations. The system is based on three main dual computers and three secondary dual computers with a fully independent electrical backup.

Villa admitted that there has been a lively debate about the extent to which the technology can impinge on a pilot’s ability to fully control the aircraft. “Some pilots see FBW in terms of limits on them rather than protection,” he said, arguing that the system actually gives crews greater latitude to fly the airplane out of trouble.

“For example, when you limit the angle of attack or bank angle, you reassure the pilot that he can’t go out of the flight envelope,” explained Villa. “If pilots know that they themselves have to stay inside the envelope, they tend not to fly the aircraft to the limits. But they know they can with FBW.” The controls will give flight crews the certain knowledge that they cannot overstress the airframe by exceeding the safety limits of the flight profile.

The consensus among those pilots who have experimented with the Falcon 7X flight-deck simulator is that the FBW controls are a blessing, giving them greater peace of mind about safety-critical situations, while also making the aircraft more stable and maneuverable. While the controls do limit pitch angles, they do not limit bank angles, as is the case for the FBW system used on Airbus airliners.

The FBW systems have been extensively tested in a Falcon 7X test-bench cockpit simulator. The flight-control system has been entirely developed within Dassault, using the same methodology it has applied to its current Mirage 2000 and Rafale fighters.

Cabin Comfort
At 76 feet 1 inch, the 7X will be about 10 feet longer than the Falcon 900EX. It will have the same 6-foot 2-inch stand-up cabin, but with eight feet more cabin length and a width of 7 feet 8 inches it offers a significantly more spacious cabin volume of 1,500 cu ft, allowing greater comfort and flexibility for the longer-range missions it will undertake. (The 900EX’s cabin volume is 1,250 cu ft.)

The new cabin is expected to be markedly better in terms of natural light, with 40 percent more window area from the 28 panes that line the fuselage. The move to a windshield consisting of four curved windows, rather than the six flat windows on previous Falcons, is the main difference in terms of external appearance.

The program is currently backed by firm orders for 40 aircraft, which were placed soon after the fall 2001 launch. About two-thirds of these orders came from existing Falcon customers. Dassault now intends to develop other new Falcons from the technological foundations laid by the 7X program.

According to Villa, the process of bringing the Falcon 7X to life has changed Dassault “profoundly” as a company. In what he characterized as “an industrial revolution,” Dassault is “learning to listen more and to give its partners more independence, because we now realize that there is more than one way to build an aircraft.” All the 7X partners are sharing the program’s risk on the same terms as Dassault–investing when Dassault invests and getting paid when Dassault gets paid.