Technology Update
Oven-ready Airbus
 The 300-ton autoclave being readied for relocation. |
High technology in aerospace engineering does not always equate to miniaturization and light weight. An example of that is the 300-ton, 40-m long autoclave—believed to be the largest of its type in Europe—that will be used in the "creep-forming" process to manufacture the aluminum wing skin panels for the forthcoming double-deck Airbus A380 at Airbus UK's production facility in North Wales.
Creep forming is the technique used to shape and strengthen aluminum sheet. The flat skin is formed over the surface of a shaped tool before being placed inside an autoclave and subjected to a heat-treatment cycle, which induces a combination of complex stress relaxation to achieve the required shape. But the size of the autoclave needed for the A380 required some innovative engineering by Aeroform. The challenge was to design an autoclave capable of processing a high-mass component over 30 m in length and of varying shape and thickness. It was clear that the traditional method of axial heat flow would not be effective in this particular creep-forming process, so Aeroform developed a circumferential airflow system modeled via fluid dynamics and finite-element analysis.
 Aeroform has developed a circumferential airflow system for its 40-m long autoclave used for creep forming wing panels for the Airbus A380. Click to enlarge |
The Circumferential Airflow Technology System achieves hot air impingement directly to the wing skin surface in a series of individually controlled zones. Each skin is processed under heat and pressure for up to 18 h, during which time the temperature fluctuation in the component must be maintained at ±2°C or more. Maximum temperature reached is 220°C.
The system incorporates Aeroform's patented, gas-fired radiant tube technology and achieves optimum heat transfer with the aid of nine separately controlled fans. Heat input and fan power for each zone can be varied individually, and each zone has its own water-cooled heat-rejection capability. The company claims the result is a totally software-programmable, individually controlled environment allowing the heat input to the component to be accurately profiled along the entire length of the skin.
- Stuart Birch
New landing gear test facility
 Photo-elastic testing of Airbus A340-600 main landing gear is done at Messier-Dowty's new test facility. |
Messier-Dowty, a Snecma Group company, has inaugurated a new landing gear test center in the UK. The facility is 60% larger than the former test center used by the company. Its biggest test rig has a mass of about 250 t, is 10 m high, and has a 30-m2 template with a loading capacity of 1000 t force. The specifications allow for critical strength and fatigue tests, where the landing gear is subjected to loads well in excess of those likely to be experienced in real life.
Forces similar to a fully loaded Airbus A340 can be applied in pre-determined sequences to simulate extended periods of operational use. Also, new rigs are being installed that are designed to test entire landing systems, adding door movements and other subsystems to landing gear deployment and retraction.
 Testing at the new facility includes a strength test on the main landing gear of the RAF's new anti-submarine reconnaissance aircraft, the Nimrod MRA4. |
Photo-elastic testing and hydraulic component and seal development can be carried out at the center, which is fully networked, facilitating data review and analysis throughout the 3000-m2 building.
Dowty developed the internally sprung aircraft wheel and the fully retractable landing gear for both commercial and military aircraft in the 1930s. In 1995, Messier-Dowty was created as a joint venture with Snecma Group, linking test centers in the UK, France, and Canada. Snecma became sole owner of the company four years ago.
- Stuart Birch
