Designated as an “outsize cargo freight aircraft,” like its Airbus A300-600ST Beluga predecessor, the BelugaXL is designed to support Airbus’ production ramp-up and fulfill increasing transport volume requirements for oversized aircraft components beyond 2019.
On June 6, a joint team from Office National d'Etudes et de Recherches Aérospatiales (ONERA) – internationally known as “The French Aerospace Lab” – and Germany’s Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) completed an eight-day course of static ground vibration testing (GVT) on the new model.
The new BelugaXL model is based on the A330-200 freighter and boasts approximately 30 percent more cargo capacity than the original Beluga, enabling it to carry two A350 XWB wings instead of one. The new aircraft reuses an extensive list of existing components and equipment; however, the unpressurized cargo hold incorporates 8,000 new parts and takes three months to mount.
The test results provide Airbus with valuable information regarding the behavior of its aircraft before the first flight takes place later this summer – an important step in the certification of a new giant.
The joint ONERA and DLR team performed the tests in compliance with the challenging technical specifications tests, while providing processed data in near real time. The rapid measurements took only four days for each structural configuration: one with an empty fuselage and one while the fuselage was loaded with a heavy, tunable payload.
ONERA and DLR, with their long experience in aircraft GVT, have formed a joint team for Airbus GVT since 1999, notably performing tests on the A320neo, the A350-900, and the A380.
“We at DLR are proud to have a long tradition of performing ground vibration tests together with ONERA, having already done this for 10 Airbus prototypes. We are aware of the great responsibility attached to the confidence that Airbus has in the two research organizations. Test by test, DLR is providing all its expertise. GVT methods and analytics are being continuously improved within DLR’s aeronautics research program,” said Rolf Henke, DLR executive board member for aeronautics research, during a joint visit to the test site in Toulouse, France.
GVT is a key part of the overall test program for every new aircraft, and a prerequisite to obtaining airworthiness certification. The experimental test data provided by GVT are useful to update the mathematical structural model of the aircraft, predict the vibration amplitudes during operation, and demonstrate freedom from flutter risks – where airframe instability occurs because of an interaction between aerodynamic, inertial, and elastic forces – throughout the flight envelope.
ONERA in collaboration with DLR performed GVT of the BelugaXL over eight testing days using several hundreds of external accelerometers while the aircraft was stimulated by external shakers or seismic exciters. The objective of GVT is to measure the dynamic behavior of the aircraft and confirm theoretical models of various flight conditions; test data also helps clear the aircraft’s flight envelope.
The latest, cutting-edge exciter technologies were used to generate vibrations in the aircraft. ONERA reported that more than 600 sensors, 7,000 meters of cable, and 300 meters of optical fibers were installed on the fuselage, empennage, engines, and wings for the BelugaXL GVT. The team identified 30 different locations for the 80-kilogram shakers for the two- to three-hour tests.
Now in its heavy ground test phase, the BelugaXL’s airframe is undergoing a total of 72 development and certification ground tests, which began with weighing the aircraft at “pitch zero” and then at “pitch nine,” lifting the aircraft’s nose by 3.5 meters to determine the empty weight center of gravity.
Next, the team will perform the standard loads and horizontal tailplane tests, followed by separate evaluations involving the dorsal fin and vertical tailplane. The heavy ground test phase involves carrying out tests on the aircraft that would usually be conducted on a static cell.
“It is unusual for us to perform tests like load calibration using the generalized finite element method of analysis on an aircraft which will fly, as we usually use a dedicated clean aircraft without any systems inside,” explains BelugaXL Aircraft Configuration Leader Arnaud Puyo.
Although the test configuration may be off-nominal, Airbus has succeeded in keeping things on track thanks to early analysis of the requirements and excellent multidisciplinary collaboration between the design office, laboratories, and test and program teams.
Take a look at the Airbus BelugaXL’s special “smiling” livery, selected by Airbus employees.
William Kucinski is content editor at SAE International, Aerospace Products Group.
Contact him by e-mail at email@example.com.
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