Bombardier’s specification for the Global 7000 must be among the most ambitious yet attempted in business aircraft design. The Canadian airframer is creating an aircraft capable of carrying eight passengers and four crew 7,400 nautical miles at Mach 0.85, yet certified as standard for steep approaches into airports exemplified by London City.
At the top end of its performance range, Bombardier says the Global 7000 will reach Mach 0.925, although operators will be more interested in its typical Mach 0.9 cruise at an initial 43,000ft cruising altitude, rising toward the 51,000ft maximum operating altitude.
New-generation General Electric Passport engines and an advanced transonic wing are major factors helping Bombardier achieve this rare combination of range, speed and airfield performance. Global 7000 pilots will also appreciate the aircraft’s extensive avionics fit, integrated under Bombardier’s Vision system, along with fly-by-wire controls and “the security of the industry’s most complete flight envelope protection”. Meanwhile, passengers will relax or work efficiently using the aircraft’s standard Ka-band connectivity, while streaming high-definition content onto the Global’s large screen TV system.
It’s a configuration the related Global 8000 will share. Shorter by 9ft, the Global 8000 promises the longest range of any business aircraft ever, but although it appears to have survived rumors of cancellation, it is not yet subject to a published development timeline. Steve Patrick, director, flight test operations and safety, Global 7000 Flight Test Team at the Bombardier Flight Test Center (BFTC), is taking on the challenge of preparing the extraordinary Global 7000 for service.
The first Flight Test Vehicle (FTV1), manufacturer’s serial number 70001, registered C-GLBO, completed the type’s maiden flight, from Toronto’s Downsview airport, on November 4 last year. Describing the sortie, Patrick says, “The flight was dedicated to testing basic system functionality and assessing handling and flying qualities. It lasted approximately 2 hours 27 minutes, during which all flight controls were exercised. The pilots reported that the systems and aircraft performed as expected.
The flight crew conducted a climb to 20,000ft and the aircraft reached a planned test speed of 240kts.”
A Global 5000 business jet flew ‘chase’ on the maiden sortie, capturing air-to-air photography and video. It also enabled visual inspection of the Global 7000 in flight,
a vital function checking for lose panels or other structural irregularities.
First flight was the culmination of a long process of definition, design and ground test. The Global 7000 program’s primary driver is the requirements of its customers, as Patrick explains: “Customer feedback throughout the Global 7000’s development is important to Bombardier. Even before putting pen to paper, our industrial design team worked closely with our engineers and customer representatives to understand what defines a truly exceptional cabin experience.”
Subsequent testing included a plethora of techniques. “Computer modeling and simulation are used in many areas of aircraft design. Aerodynamic modeling is the basis for developing the flight control laws, which are further tuned on test rigs prior to flight.””Computer models also allow us to assess the vibration characteristics of the structure in order to avoid flutter. Noise is predicted using acoustics models to assess the aircraft noise footprint. Thermodynamic modeling is extensively used to predict temperature in enclosed spaces and assess potential failures, such as duct ruptures. Ice accretion models are used to predict the size of ice build-up on unprotected surfaces. System simulation models are used extensively to assess behaviors in failure conditions.
“We used a series of wind tunnel tests to validate the Global 7000’s aerodynamic configuration. These included low-speed, high-speed and high-lift testing, as well as icing tunnel tests. The trials allow us to fine-tune the key aerodynamic parameters of lift and drag. They also provide valuable loads information that’s used to design the structure.”
Ground-based rigs were used in an extensive trials campaign that informed aircraft configuration development, validation and optimization in the years preceding first flight and, according to Patrick, will support subsequent certification flight tests.
He notes, “Ground-based testing is aligned with modeling and simulation of components, and embedded within the product design and development processes at Bombardier. It ranges all the way from details at structural component level to highly integrated rigs that accurately represent the entirety of multiple aircraft systems, including avionics, systems such as electrical and hydraulic power, primary and secondary flight controls, and many others.
“Ground-based trials on the FTVs, for example, include high-intensity radiated field/electromagnetic interference, fuel system calibration, and cold and hot weather testing. In addition, ground-based testing is an important part of the certification program, with many of the ground rig tests contributing information used to certify
Patrick says the Global 7000 test rigs and simulators played a crucial role in crew preparations for first flight: “Bombardier Flight Test Center crews make extensive use of simulators and test rigs prior to flight testing. The Reconfigurable Engineering Flight Simulator [REFS] allows for development and preflight validation of control laws. The System Integrated Test Simulator [SITS] enables more specific testing of individual systems and their compatibility with other systems; for instance avionics, powerplant and fuel can be assessed simultaneously. Finally, the Engineering Simulator (ESIM) is a fixed-base platform combining a fully representative aircraft cockpit, actual aircraft components and software, and aerodynamic flight models with a state-of-the-art visual system. It allows every mission to be pre-flown, if required, with the aircrew completing the premier mission on the ESIM prior to actual first flight.”
Each of the five FTVs is being configured to suit its primary mission. “This includes operation stations, equipment racks, fixed and transferrable ballast, and controls for external measurement devices–trailing static cones, liquid water content icing probes, and so on,” Patrick says. “Every test aircraft has extensive instrumentation configured to suit its primary mission. This will involve analog and digital parameter measures on airframe, engines, systems, electrical, avionics, air systems, pneumatics, hydraulics, fuel and any other system under test. Digital video cameras are used to oversee cockpit activity, with a series of external cameras used to view landing gear, wing leading edges, engine inlets, tail, etc.”
Global 7000 power comes from the General Electric Passport turbofan, installed as an integrated propulsion system in a Nexelle nacelle. Although designed to suit the particular range and speed requirements of the Global 7000 and 8000 models, the Passport also leverages technologies proven in the manufacturer’s own GE90 and GEnx commercial engines, and the LEAP turbofan created with Safran.
GE announced the Passport’s FAA certification on May 23 last year, after an extensive test program that began in November 2013 with its ground running of what it calls the ‘First Engine to Test’. April 2014 saw icing certification testing before flight trials on the port inner-engine pylon of GE’s Boeing 747-100 testbed, between December 2014 and April 2015.
At the time of the certification announcement, GE said the engine had “accumulated more than 2,400 hours and 2,800 cycles in ground and flight testing. By the time the Passport enters into service, it will have accumulated the equivalent of 10 years of flying for a Global 7000 or Global 8000 aircraft operator with more than 4,000 hours and 8,000 cycles.”
On November 21, 2016, FTV1 flew to the Bombardier Flight Test Center in Wichita, Kansas. Patrick confirms the move was ahead of schedule, but declines to comment on the subsequent test timeline: “For competitive reasons, we are not disclosing further milestones in the flight testing program. We’ll communicate all relevant milestones upon their completion.”
Bombardier will achieve those milestones through a program of carefully designed and performed individual flight tests, explains Patrick: “Each flight follows the ‘recipe’ developed over the years by BFTC personnel and includes lessons learned from the recent testing and certification of the C Series airliner. Early on the morning of the test, the team assembles for a short ‘configuration briefing’ to confirm that the aircraft is set up as requested and no new items need to be considered. The crew then steps to the aircraft and the engineers go to telemetry if the flight is being monitored in real time. Mission durations vary based on operational requirements.
“With the flight completed, data is passed to the maintenance and engineering teams; they discuss the test results and complete their initial data review. Some data is analyzed in real time via telemetry or onboard test personnel. On completion of the debrief session, the teams move on to preparations for the next flight, including reviewing the test card. Each aircraft has multiple crew members who stagger their activities such that testing can be supported every day if required.”
Patrick is also happy to reveal details of trials planned to take the Global 7000 FTVs away from Wichita: “The test aircraft will deploy for several reasons, including hot and cold environmental testing, runway performance, natural icing, high-altitude airport compatibility, and ‘route proving’, which we refer to as ‘function and reliability’ testing. Many of the deployments are in the USA and Canada, but international deployments can also be expected.”
Speaking in mid-January, he added, “We won’t disclose the length of the flight test program, but it’s progressing very well and we have a robust schedule planned. We’ve accomplished 18 flights and more than 54 hours of flight time. We remain focused on meeting the program’s development and certification schedule and the aircraft’s entry-into-service in the second half of 2018.”
Paul E Eden is a UK-based freelance writer and editor specializing in the aviation industry.
This article was also published in the March 2017 issue of Aerospace Testing International magazine.