Istres in southern France, close to Marseille, has always been a special place in French and European aviation. This is where famous airplanes such as the Rafale fighter and the Airbus A380 are flight tested and finetuned during development and certification. It is a large military airbase with active units such as KC-135 tankers operating, but also has civil ramps and hangars for the flight test departments of French companies such as Dassault.
The usually sunny weather, more then enough special use airspace, and a location close to the Mediterranean Sea amongst purple lavender fields make it a great place for flight testing. I was quite happy to go there when Dassault Aviation invited me recently to fly the new Falcon 7X.
The introduction to the 7X began, however, at Dassault’s headquarters in Paris St. Cloud. Bruno Rolland, Vice President Falcon Programs and his staff spent an afternoon to brief us on the status of the 7X program. In 2001, Dassault announced at the Paris Airshow that it would design and build the first all digital flight control (fly-by-wire) executive aircraft ever. Since then, the aircraft has received FAA/JAA certification in April 2007, and since June 2007 the first aircraft have been delivered to customers. The 7X is the largest aircraft in the Falcon fleet and competes with the Gulfstream 550 and Canadair’s Global Express. It offers a range of 5950 nautical miles (with 8 passengers at Mach 0.80 and NBAA fuel reserves) and a comfortable cabin with a low sound level and a volume of over 1500 cubic feet. The cabin altitude is only 6000 ft at the maximum cruise altitude of 51000ft, the initial cruising altitude after takeoff at maximum weight (69000 lbs) an impressive 39000 ft. An innovative air distribution system controls the temperature evenly throughout the cabin to a degree.
The challenge for Dassault was to build a long range executive aircraft that would offer low direct operating costs through advanced aerodynamics and structures and maximum comfort for intercontinental flights that could extend over 12 hours or more. The French manufacturer achieved this goal by extending the 900EX cabin by 7 ft (1.8m), attaching a new transsonic wing with winglets and controlling the aircraft with all digital fly-by-wire flight controls.
The flightdeck features the very much advanced EASy glass cockpit based on Honeywell EPIC architecture. The EASy cockpit is available current Falcons with conventional flight controls as well, but fly-by-wire enabled engineers and test pilots to go all the way with their philosophy of flight path control.
Very early the next morning we flew from Paris to Marseille on Air France and drove the 45 minutes to nearby Istres on the Western coast of the Etang de Berre, a large bay near Marseille. While Air France certainly made this flight pleasant, as always the humilitating procedure of belt and sometimes even shoe removal at the Orly security checkpoint made it quite clear why anyone who can afford it flees public airline service in favour of an executive jet.
After passing several guarded gates at the Istres air base we finally arrived at the flight test ramp. Dassault’s 7X F-WFBW, serial number 1, was waiting for us in its distinct and colorful livery. Senior chief test pilots Philippe Deleume and Philippe Rebourg, whom I had met at an earlier 900Ex Easy flight already, introduced me to their new baby and invited me to take the left seat.
This being the flight test department, a test order had been prepared that we would follow throughout the flight. Even though the 7X is certified and already in commercial service, serial number 1 is still a test aircraft with a full suite of testing equipment and telemetric data transmission and communication systems installed. The interior is decidedly non-executive with just two passenger seats and several water tanks to simulate weight distribution.
I settled in the comfortable seat and found the cockpit spacious and the windows large. Dassault has done away with the typical Falcon look of five smaller cockpit windows, the four new large windows give exceptional visibilty. Rudders and the vertical position of the seat could be adjusted electrically, forward and sideward motion manually. I placed my left arm on the lower arm rest, putting my hand in a comfortable position to operate the fly-by-wire sidestick. Four large displays, two PFDs (Primary Flight Displays) and two MFDs (Multifunction Displays) organize all navigation, performance and systems information. Two CCDs (cursor control devices), one for each pilot, are used to move between the displays and to enter and select data.
As on other EASy cockpit jets, we began to feed the flight management system with the data for this flight. Our takeoff gross weight was 51500 lbs (23400kg) including 12000 lbs of fuel. Philippe Deleume guided me through the pre-start procedures from the right seat, as Philippe Rebourg observed from the jump seat. The easy and intuitive operation of the Easy cockpit made our task quick as the cursor jumped from required data entry field to the next. We used the two CCDs on the center pedestal to complete our task.
After starting all three Pratt&Whitney Canada PW307A engines with APU power, we went through the electronic checklist to get ready for takeoff. Unlike in earlier versions of the EASy cockpit, the 7X requires the use of the electronic checklist which is displayed on the lower MFD. Paper checklists are not acceptable anymore. Dassault realizes, however, that operators have different philosophies guiding their normal procedures. Therefore, through a third party provider, electronic checklists can be customized without a change of certification being necessary.
The checks did not take long. The flight control check is especially neat, since it is done fully automatic and the pilots do not have to touch the sidesticks to perform it. Dassault’s digital flight control system (DFCS) is a fly-by-wire system that feeds sensor data such as air data and IRS (Intertial Reference System) information as well as pilot commands to two flight control computers, MFCC and SFCC (Main and Secondary Flight Control Computers). Each of these FCCs has three channels and sends signals to hydraulic servo actuators on the wings and empennage through an ACMU (Actuator and Control Monitoring Unit). Hydraulic power of three 3000 psi systems is then used to operate the flight controls. And to test all this before flight, you just press a button and observe.
A similar help is available to check the circuit breaker panels: Since all CBs have been moved outside the flightdeck, a dedicated CB page monitors CB status and can also be used to reset some of them.
The electrical system layout of the 7X is very robust, as electrical power is the life blood of this aircraft. In addition to three 500 Amp engine driven generators two lead acid batteries supply the 28V DC system. A RAT (Ram Air Turbine) is deployed to generate electricity from the airstream if all other generators fail. The digital flight control system has its own permanent magnet generators on each engine, independent of the electrical system.
Even air data are transmitted electronically. Four Smartprobes combine sensors for dynamic and static pressure, temperature and angle-of-attck with air data computers mounted right to the probes. The resulting data are distributed electronically and RVSM compliant, even if one probe fails.
With all checks complete, we taxied to runway 33 to take off into the Mistral which was blowing from the north with up to 30 knots. There is no nosewheel steering tiller, pilots use the rudder pedals, which are mechanically linked to eachother, to control the aircraft during taxi. Brakes are very effective and require a light touch.
Slats and flaps were set to SF2, we advanced the throttles to full take-off thrust and released the brakes. The Falcon 7X accelerated impressively, and full aft movement on the sidestick brought us into the air swiftly. After gear and flap retraction, Philippe Deleume gave me an introduction to the 7X flight controls as we climbed to 15000 ft over the Mediterranean.
Pilots fly the 7X by requiring a flightpath with roll rate and pitch rate commands through the use of two independent sidesticks. In case both pilots operate the sidestick at the same time, the inputs are added algebraically. But dual inputs should be avoided, therefore an aural warning “DUAL INPUT” sounds, and, another great Dassault idea, the sticks vibrate to provide a tactile feedback. Each stick has four pushbuttons for Priority and A/P (autopilot) disconnect, oversteering the autopilot (TCS), radio PTT and HUD (Head-up-Display) adjustment. The priority logic is used if one sidestick fails, pushing the priority button for more then 30 seconds latches the priority to this sidestick.
Fly-by-wire, well established in military aircraft and airliners such as the Airbus A320 and the Boeing B777, allows designers to improve aerodynamic characteristics such as induced drag by relaxing stability (bringing the CG aft) and therefore lowering the required downforce on the stabilizer. While neutral stability will not be certified in civil aircraft, an aft CG reduces fuel burn considerably and is especially important for longrange aircraft. Fly-by-wire also allows the pilot to react with full control inputs in critical situations such as terrain avoidance and windshear recovery. The flight control computers will allow maximum performance while making sure that the structural limits of the airframe and aerodynamic limits such as overspeed and stall are not exceeded, resulting in a better net flightpath for most pilots. Another benefit of fly-by-wire is the ability to create a similar control feel over a family of aircraft. If Dassault chooses so, upcoming executive aircraft could probably be designed to allow a common type-rating for crews with the ensuing savings in scheduling and training.
During the entire climb and speed-up, I never had to trim the aircraft. The digital autotrim works in all three axes and took care of that. Actually, the autotrim is so reliable that it is used to compensate for assymetric thrust if an engine fails and to lower the certified VMCG (minimum control speed ground).
At 15000 ft Philippe demonstrated a special feature of this test aircraft: the ability to fly in alternate or direct law at will. Normally, the digital flight control system operates in normal law. This gives full aerodynamic and structural protection. The aircraft will not stall, since slats are extended automatically and the nose is lowered if a stall approaches. The aircraft will not overspeed, since the nose is pitched up in that case. And it will not exceed a load of 2.5g.
However, there is a 1:100.000 chance that the aircraft will revert to Alternate Law. This might be caused by a sensor error or similar. Philippe simulated this failure with a special switch on this test aircraft, and I flew the aircraft just as comfortable as before. The only difference was that the protections mentioned above were no longer available, but the aircraft flew just as stable as in Normal Law.
Philippe was not done yet. There is a 1:10.000.000 chance that Direct Law will apply. He flipped a second switch to simulate this situation as well. Now the autotrim was missing. The aircraft flew still very stable and comfortable, but just like a normal airplane, small corrections had to be made to the flightpath constantly.
This would be enough to safely certify this aircraft, but Dassault has even installed a back-up system on top that bypasses the flight control computers and controls the actuators electrically. All this shows the significant experience in fly-by-wire flight control systems that Dassault has aquired through its work on military fighters such as the Rafale and Mirage. It should be noted that even the wiring for the flight control system is distributed over the airframe to prevent failures, and the computers are also mounted in different locations.
After Philippe restored normal flight control laws, we climbed to 39000ft. With ease and comfort I did some 60 degree steep turns, demonstrating that there is no roll limit imposed on the pilot.
To get back to Istres airport, we initiated a simulated emergency descent. I reached back behind the throttles to the conventional airbrake lever and selected AB2. With descent rates of up to 10000fpm we quickly arrived at the coast and set up for a first approach to runway 33. The cabin pressure controller did a marvellous job during the steep descent, I never felt the need to equalize pressure in the ears.
Even though the headwind was strong and the air quite bumpy, the 7X was extremely stable to fly. We extended the gear and selected slats/flaps to SF3. After reading the electronic final checklist we flew down to the runway. At 100ft, Philippe called “go-around”, and I pitched up and advanced the throttles to full thrust. In a sharp left turn we joined the downwind leg again, this time with the HUD flipped down.
As I adjusted my vision to the HUD, we turned base and final. By just placing the flight path symbol on the runway beginning, it was very easy to steer the Falcon back to a final landing. After a smooth touchdown of the main gear, I lowered the nose . Braking started at about 80 knots, and by the time the center engine spooled up to reverse thrust we had almost achieved taxi speed.
As we parked the aircraft and then walked over to Dassault’s private restaurant for a delicious lunch and some good red wine with the pilots and engineers to celebrate this flight, I thought that Dassault had probably designed one of the best flight control systems I had flown. And the 7X itself is a very strong competitor in the large intercontinental executive jet market with low direct operating costs and a lot of operational flexibility. Since the maximum landing weight is 90% of maximum takeoff weight, it is possible to combine a short hop with a long intercontinental flight with no refueling in between. The 7X’s three engines provide peace of mind over water and deserts, and improved performance in difficult airports such as St. Moritz (Switzerland) and Aspen, CO. And a slow approach speed of 104 knots gives access to runways that are less then 3000 ft long.
As aircraft number 66 is currently in the assembly line in Bordeaux Merignac and production has been ramped up to a stable four aircraft per month, Dassault is working on further improvements to the 7X. Certification for the Collins EFVS (Enhanced Flight Vision System) is under way as well as CPDLC and ADS-B modifications for the future air navigation system. GPS based WAAS approaches and a synthetic vision option with high resolution digital images of terrain and obstacles displayed on a new PFD are also under development. A RAAS (Runway Alert and Advisory System) which provides aural warnings to pilots about the runway they are on and an automatic descent in case of sudden loss of pressure are also options that may be ordered in the future.
None less then Charles Lindbergh recommended Dassault’s Mystere 20 to then Pan American Airways Chairman Juan Trippe as an executive jet in the 60s, enabling the success of the Falcon series in the United States. Looking at the beautiful Falcon 7X, it is safe to say that the famous aviator was right in his appreciation of the French manufacturer.
