We visited the Bombardier Mirabel facility in May, where we were introduced to their CSeries mockup made from wood. More than a few of the assembled media people smirked about this – after all, are we not in the 21st Century?
But it turns out that this idea is not so outlandish after all. We toured Airbus’ A350XWB plant in Hamburg in July. Guess what? Airbus, using aluminum and steel, also has a physical mockup.
The story and rationale for a physical mockup is essentially this. A computer, even when working with the latest software that projects components in 3D, might limit what a mechanic has to go through in working on the airplane. A digital mockup can check virtually everything. But physical mockups are useful for debugging and maturing complex systems and components prior to first flight. For example, a physical mockup allows for aircraft factory workers to practice assembly, airline mechanics to practice maintenance and operational checks. Working with a physical mockup can sometimes also identify small issues that can be fixed.
A visitor to an aircraft factory making the parts for the next generation airplane would find himself overwhelmed by robots and accoutrements of today’s modern aircraft factory. An interesting problem is that after the machining of the latest materials with fabulous accuracy driven by lasers and multi-axis machinery; people still have to get the parts to fit together. Humans manage and monitor this process. Airbus’ A350 wing weighs 2.5 tonnes (each side) and fits in a jig, and it is humans who guide the crane and ensure the wing fits into the jig just right. This human component drives the value of creating physical mockups.
Bombardier want to great pains to explain how useful they found the wooden mockup to be. Count us among the initial skeptics, but not anymore. Airbus has an “aircraft zero” in Toulouse where it is testing all the flight systems. In Hamburg it has “cabin zero”, where all cabin-related system functions are tested on 15 benches plus a physical mockup. When asked why they have such a thorough program, it was explained with a smile, that Airbus has learned lessons from the A380. One of the lessons is that you had best replicate the cabin as close to reality as possible. Airbus believes that doing this could save between 25%-30% of the flight test time. This confirms what Bombardier has indicated; through use of its CIASTA, enables them to run tests in parallel to save significant and flight test time, and compress the development schedule.
The similarities in approach and philosophy between the Airbus and Bombardier approach have left us with an entirely new perspective on the need for physical mockups in a digital world. Modern aircraft are high-tech devices and systems checking and testing go on continuously. There are so much software controlled systems, and digital mockups benefit from analogue mockups. Physical mockups help to debug and mature, even improve, complex systems and components prior to first flight. Besides, software updates come frequently and these need to be checked. The updates are not only specific to aircraft controls, there are also IFE and other communications software.
An airplane consists of many highly intricate parts – and many of these could conflict with one another because they are software driven. On the A350 the controllers and other electronics bays under the flight deck looks identical to what you see in an IT co-location site. Airbus runs at least weekly software updates between “aircraft zero” and “cabin zero”. This close cooperation is matched by the Bremen facility which tests the doors (A350 are doors made by eurocopter in Donauwörth, Germany) having a real time connection to Hamburg’s “cabin zero”.
An appreciation of the complexity involved with making a next generation airplane was underscored by noting that once Airbus has the core design down they then tweak it for “head of version”. “Head of version” is a term that describes the first customer version of an airplane. Airbus (and other OEMs) test the head of version extensively because it is the benchmark airplane for other airplanes of the model type for that customer. Airbus tests new functions, new features and combinations of these to ensure no conflicts and perfect harmony system-wide.
Aircraft manufacturers have learned the lessons and costs of delays, and new programs benefit substantially from the use of physical mockups. Even in the 21st Century a physical mockup is very useful.