Aerospace designers have cunningly employed the term ‘unobtainium’ to refer to exotic or costly materials - or even when researching the development of a material that is perfect for their needs in every respect - except that it doesn’t actually exist! Unobtainium can also be applied to those materials that are capable of withstanding the extreme the temperatures required in the latest jet engines. Often, designers will daydream of designing an aircraft which requires components with the strength or resilience beyond that of available materials. Meanwhile, titanium continues to remain the industry’s metal of choice, and whilst its unique high strength-to-weight ratio properties, and corrosion and temperature resistance ensure it has consolidated its future as a firm favourite, other non-metallic materials like carbon fibre reinforced plastics have eroded the metallic dominance within aerostructures. However, exacting safety demands mean we’ll always be faced with arduous material certification requirements. Imagine a giant version of the Scales of Justice, where on one side you have a finished aircraft, and on the other a huge pile of documentation. The upshot being that the aircraft won’t fly until the documentation is the same weight as the aircraft! For whatever story might unfold, designers live in hope that somehow base metal can eventually be turned into gold. They continue to look for that sweet spot; they’re still eager to tap into that mother lode at the end of the runway. Mike Richardson, editor
