Although a one-off, aircraft AA-1 has validated what the JSF team calls the “digital thread” – the electronic design database that runs from engineering through to manufacturing, and beyond. Constantly updated, this database of Catia three-dimensional solid models defining the F-35 stitches together the partners and suppliers around the world.
“AA-1 proved out the manufacturing processes using the digital thread – all of us using the same electronic master model,” says Edward Linhart, Lockheed Martin vice-president F-35 production operations.
“It went together better than anticipated – less than 10% off anticipated manhours. And that was mainly waiting for parts – we won’t make that mistake on the second one.”
The digital thread allowed manufacturing engineers to get more closely involved in the design, and to get an early start on developing numerical-control programs from the Catia models for automatic tape-laying and high-speed maching, resulting in a better first-time product.
“When parts went through we did not assume 100% yield – but it was over 70%, which is phenomenal for a first-off aircraft,” says Tom Fillingham, BAE Systems F-35 programme manager.
This design thread also reduced suppliers’ scrap and rework levels to a “historic low”, says Janis Pamiljans, Northrop Grumman F-35 programme manager. “This helps cut costs and helps affordability. We’re also seeing all the results of this hard work in terms of flow targets, which are beating all expectations,” he says.
Bobby Williams, air vehicle team lead, says: “Drawing release using the digital thread proved to work quite well, but we can do better and we are rolling [the improvements] into the design process to minimise the cost and schedule for the first STOVL.”
“AA-1 was quite well designed and machined, but we learned a lot that we are putting into BF-1,” says Fillingham. “We refined our manufacturing technologies, and with BF-1 we are getting even better quality and really seeing the benefits coming through.”
The digital thread joining the partners was tied tightly during the intensive effort to reduce the weight of the STOVL variant. The revised design came about through close work between the three team members, which share the practice of using key employees as “best athletes” to lead certain tasks irrespective of their parent company.
“We have Lockheed Martin and BAE people who will lead an integrated product team here and to this day you still have IPTs where a Northrop Grumman employee leads an Lockheed Martin or BAE team,” says Pamiljans.