Dassault’s next business jet to enter service will be the twin-engine 6X, on track for certification and first delivery next year. The third flight-test aircraft, equipped with a full interior, made its first flight on June 24. A fourth and final flight-test 6X will have a production interior and be used for a two-month-long global endurance test.
The large-cabin 6X picks up where the now-canceled 5X left off, taking on the job of meeting the need for a new widebody twinjet after the 5X’s planned Snecma Silvercrest engine suffered development problems (the reason for the 5X's cancellation). Compared to the 5X, the 6X, with a cabin 20 inches longer, weighs more and is powered by Pratt & Whitney PurePower PW812D engines. The added length enables the 6X to keep the unique skylight in the galley area but also the airframe’s 30 larger windows as well as adding more room in the forward galley or crew rest area or more space in the aft lounge.
Notably, the 6X's cabin features the largest cross-section dimensions of a purpose-built business jet—Dassault calls it an “ultra widebody”—with a height of 78 inches (1.98 meters) and width of 102 inches. By comparison, the flagships of competitors Bombardier (Global 7500) and Gulfstream (G700) have smaller cabin dimensions, although they are much longer. The Global 7500 cabin measures 74 inches high and 96 inches wide. The G700 cabin is 75 inches high and 98 inches wide.
Baggage is accommodated in a 155-cu-ft compartment inside the pressure vessel, plus there is another unpressurized compartment of 76 cu ft. Up to 16 passengers can fly on the 6X in three lounge areas. With the increased cabin width, the aisle is five inches wider than earlier Falcon models.
The 6X carries more fuel than was planned for the 5X and thus can achieve a maximum range of 5,500 nm at Mach 0.80 or 5,100 nm at Mach 0.85 with eight passengers and three crew. One significant difference is that the 6X is Dassault’s first business jet with a nitrogen-based fuel pressurization system to lower the risk of fuel tank ignition, although earlier Falcons do have pressurized fuel tanks.
The 6X’s maximum operating Mach number is Mach 0.90 and maximum altitude is 51,000 feet. Powered back to Mach 0.85, the 6X can link Los Angeles and London, New York and Moscow, or Paris and Beijing while maintaining a 3,900-foot cabin altitude at FL410.
Maximum landing weight is 85 percent of the 77,460-pound mtow, making possible short flights followed by longer unrefueled legs. Takeoff distance at sea level and mtow is 5,480 feet. Approach speed at typical landing weights (eight passengers and three crew) is a low 109 kias, and coupled with steep approach capability to 6 degrees, landing can be safely done at smaller airports such as London City, Lugano, and Saint-Tropez.
A feature that facilitates short-field performance is the fly-by-wire flight control system’s use of electrically driven flaps and flaperons. The flaperons act as both flaps (increasing lift) and ailerons (roll control) and are a first for a business jet. With the control surfaces working in tandem, lift-over-drag augmentation improves steep approach visibility, control, and comfort. The 6X’s wing is updated with new structural architecture and a curved trailing edge, adding to the buffet margin and lift/drag ratio to lower the impact of turbulence, according to Dassault.
Nosewheel steering is integrated into the fly-by-wire flight control system “for safer runway handling in strong crosswinds or on wet runways.”
The Pratt & Whitney PurePower PW812D ("D" for Dassault) engines that power the 6X each deliver 13,500 pounds thrust. The PW812D has a 44-inch single-piece fan and 4.5:1 to 5:1 bypass ratio and features the low-emissions Talon X combustor. Specific fuel consumption of PW800s is some 10 percent less than that of current in-service engines, according to Pratt & Whitney.
In a departure from previous designs, Dassault elected to source the nacelle design, integration, and production from Pratt & Whitney sister company Collins Aerospace (formerly UTC Aerospace Systems) instead of developing a proprietary system or working with the engine OEM to deliver the nacelle along with the engine.
On the 6X flight deck, pilots will manage the jet with the latest version of the Honeywell Epic-based EASy III avionics, which also features four 14.1-inch displays, Honeywell’s IntuVue RDR-4000 radar, and the FalconEye head-up display with combined vision system (overlaid synthetic vision and enhanced vision system imagery). FalconEye is standard in the 6X and was developed with Elbit Systems. Dassault expects to receive operational credit approval for use of FalconEye’s enhanced vision system for instrument approaches to 100-foot minimums in the 6X.
FalconSphere II electronic flight bags are mounted in the console. Updated processors and displays make the EASy III avionics power up and down faster than ever.
The widebody cabin extends into the flight deck, giving pilots more headroom and 30 percent more window space and allowing entry and egress to the front seats without having to climb over the center console. Pilot seats also recline to 130 degrees.
Following the flight of the third 6X, Dassault Aviation chairman and CEO Eric Trappier said, “This latest flight is yet another sign of the smooth progress we have been making with the 6X test program. We have been consistently impressed with the flight performance and handling of the 6X and the reliability of aircraft systems.”
5X Support Already Ramping Up
Meanwhile, the French airframer is also preparing to support the business jet’s 2022 entry into service—preparations that began long before the first 6X's first flight on March 10. Key among those preparations is ensuring the reliability of the 6X’s systems and components, according to Jean Kayanakis, senior v-p of Dassault’s worldwide Falcon customer service and service center network.
To do that, Kayanakis said Dassault’s teams and partners are going through intensive equipment testing and screening, including a process the company calls highly accelerated life testing (HALT). Under HALT, components are exposed to extreme conditions such as vibration, temperature, and humidity, or “shake and bake” testing, Kayanakis explained. “If they don’t fail through all of this, they’re a lot less likely to fail in the aircraft.”
Product support staff also are involved in the Falcon 6X test program. The company has assigned seven experienced engineers and technicians to the flight-test aircraft. Their duties vary and include providing line service on the ramp, acquiring and analyzing data, and validating the FalconScan onboard diagnostic system and maintenance documents.
Technicians from Dassault Falcon Service and TAG Maintenance Services (TMS) are also part of that team. Dassault acquired TMS as part of a roll-up of 19 MRO facilities—including Luxaviation’s ExecuJet MRO centers and Ruag maintenance and FBO operations at Geneva and Lugano airports—two years ago.
Additional staff at Dassault’s Falcon Command Center (FCC) in Mérignac, France, are conducting evaluations of raw data from the test aircraft’s FalconScan advanced diagnostic system downloads. Last November, Dassault moved FCC and product support to Mérignac to bring those operations closer to its engineering, production, flight test, and service center there.
Kayanakis said the company has been running failure simulations since April with FalconScan on the test bench to simulate as many fault configurations as possible. “FalconScan monitors 100,000 parameters, so you can easily imagine that this system can track a lot of fault scenarios,” he said.