Airlander 10, the world's longest aircraft, emerged from its hangar in Bedfordshire, UK, last month and delighted the world when on August 17th 2016 it took its maiden flight.
The Airlander 10 is an unusual vehicle. Rigid like a zeppelin but maintaining its shape from internal gas pressure like a blimp, the gargantuan hull is filled with helium and its internal diaphragms are designed to support its longitudinal shape, making it safer than other airships and giving it the capacity to carry loads of some 50 tonnes. Achieving the lightweight strength demonstrated in its first outing does not happen overnight, with composites engineering and manufacturing specialist Forward Composites perfecting the structure of the Airlander 10 prototype over six years.
Technical Director and Co-Owner of Forward Composites Ed Collings knows more about what the Airlander 10 is made from than perhaps anybody else, becoming involved in the project back in 2010 at Lola Composites before it was bought by Forward.
"I know far too much about this," he joked. "It has taken up a few years of my career."
Unsurprisingly for a 92-metre long airship, the Airlander 10 presented some unique challenges for Forward, including tooling and building a robust structure that will fly.
The mission module alone is 22 metres long, and the cost of tooling components of this size would be prohibitively expensive.
"We used some quite novel methods on the tooling manufacture," said Collings. "We manufactured the payload module and we also did the design and FEA (Finite Element Analysis) assembly, so we use techniques that are actually quite common in motorsport."
Engineering systems commonly used in F1 racing were preferable to Collings and the team at Forward not only because of the short timeframes both the Airlander and an F1 project impose, but because Forward has an expert background in motorsport design and technology built on 53 years of Lola specialising in this elite engineering segment.
"The tools we used in FEA and some classical stress calculations are derived from F1 methodology," explained Collings. "A lot of the manufacturing process was very similar to F1 technologies with some alterations due to the size of the structure and the large amounts of material. We used thicker layers of composite material and therefore applied fewer layers to build up the equivalent thickness to obtain the right structural properties, but conceptually it's quite similar to an F1 car."
Right first time
There is such a vast juxtaposition between a zippy F1 racer, zooming around a racetrack like a dragonfly skimming a pond, and the cloud-like sleepiness of an airship drifting across the sky and this comparison was not lost on Collings. But even though the design and engineering techniques and the schedule are very similar or even the same, what is different is the 'get it right first time" culture in aerospace.
"You have to design things right and you design things once, there isn't time to go through various iterations of the design so it requires experienced people to get a full understanding of all the parameters affecting the product and deliver the optimum solution from the outset," Collings stated.
Forward did what it was required to do following this strict schedule thanks to its 'industry benchmark" analysis tools to analyse the composites structure down to every individual ply. Composites, Collings explained, are not isotropic materials that behave differently when pulled in different directions and Forward's analysis tools account for this, allowing the team to truly understand how many layers of material are required at specific points on the Airlander 10.
"I used the same tools I used to use in F1 and with that experience you can actually produce theoretically optimal design in a relatively short timeframe," said Collings.
Big project, big tools
Despite the familiar process, nothing about the development of the Airlander 10 was routine for Forward.
"The scale is vast," Collings stated. "We've got some of the largest facilities within a private composites company and that allowed us to manufacture 7.2m-long components in one piece without any unnecessary joints that would have to be included purely from a feasibility and practical constraint.
"So we can manufacture the moulds, laminate the components and cure them. Full 5-axis CNC machines ensures accuracy and removes any dependency on shimming and fitting on assembly ... and that's fairly sophisticated in the industry to be able to machine something of that size and achieve the fit and tolerances. That was a key challenge for us but one we overcame and it worked very well. As a result, the finished components manufactured here at Forward were fitted to the Airlander within less than a week on-site."
As well as the scale of the Airlander 10, the conditions its structure would have to stand up to posed another new challenge for Forward. The materials themselves are civil aerospace-approved, for aircraft that ascend to much colder temperatures than the Airlander 10, but Collings revealed that this did not mean the team could relax the highly technical process of picking the right resin matrix - an epoxy resin - to suit the process and unusual curing parameters.
"It comes down to experience really. Within our company, to know what materials are available and how they work and to pick the optimum material to suit all the variables is vital," Collings said.
In all, Forward's remit included the rigid structures assembled onto the hull, the cabin and 'universal space', which will be used for demonstrations in the prototype.
"We're a composite partner with HAV (Hybrid Air Vehicles, owner of the Airlander 10) we know their people very well," said Collings.
EPPM spoke to Collings just before the Airlander 10 took its maiden flight and the composites expert revealed that HAV's prospects, which extend from defence and shipping to delivering humanitarian aid to remote areas, rested on a successful launch.
"It's taken 160-something people [to get it to fly]," said Collings. "Personally, I have a lot of pride in having worked on the project and technically at Forward I'm more involved than anyone else here. I'm proud of it and it will be great to see it fly."
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