The Syensqo company, comprising the solutions, activities and markets represented in the article below, was spun off from Solvay group in December 2023.
Composite materials are building the aircraft of the future
Composite materials have been used in aerospace as a replacement for metal for more than half a century. But for a long time, their use was limited to high-end applications such as military vehicles, for which top performance took precedence over all other criteria, including economic ones.
But times have changed. Commercial sectors – whether established ones like mainstream air travel or emerging ones such as urban air mobility – are now leveraging everything that composites have to offer, driven by two complementary trends: the urgency to upgrade their sustainability profile, and the largely improved accessibility of composite materials both from an economic and technical point of view.
Increasing the use of composite materials in aviation
The sustainability aspect is quite straightforward. Because they weigh so much less than metal, composites allow aircraft to burn less fuel and therefore reduce their emissions. “Since the early 2000s, lightweighting has come into the general focus of the industry for fuel efficiency reasons”, confirms Stephen Heinz, Vice President R&I for Solvay’s Composites business unit. “Considering the fuel burn of a plane represents more than 95% of its carbon footprint, any impact on its consumption has a big effect.”
Simultaneously, the total cost of ownership of composites compared to metal has decreased over the years. Today, with the barrier of cost lowered, their adoption boils down in large part to adapting manufacturing processes. “As composites become used to replace more and more metal parts, new applications are opening that need to be addressed,” explains Stephen. “But there is still a lot to do in order to proliferate composites.”
The key question here is manufacturing rates. In the early 2000s, when twin-aisle commercial aircraft programs such as the Airbus 350 or Boeing 787 started switching to composite materials on a massive scale (for lightweighting purposes, but also for reasons of easier maintenance and better longevity compared to metal), they overcame the technical challenges this involved and progressively reached a proportion of up to 50% of composites in these models. This meant no longer using metal for crucial structural parts in the fuselage and wings.
But these planes are manufactured at relatively low rates of a dozen units a month, and unfortunately, the technology used isn’t scalable for smaller, single-aisle aircraft and their rates of 50 to 60 planes per month. Manufacturers aim to raise to 100 planes per month over the next decade to answer rising demand from the global air travel industry.
Single-aisle planes are currently made of approximately 15 to 20% of composites, excluding major structural parts such as wings or fuselage, However, to increase this proportion to 50% or more, a complete rethinking of their entire manufacturing process is required. “To do this, the industry needs to come together to work on design, materials and manufacturing jointly,” says Edoardo Depase, Solvay’s Head of Marketing and Business Development for Aerospace. “Each of these pillars influences the others, so collaboration is key to find the best solution. This of course includes materials providers such as Solvay.”
Having an efficient aircraft that reduces operational costs by consuming less fuel will continue to be more and more crucial for the aviation sector.
Composite materials are a key enabler for urban air mobility
In the case of urban air mobility, it’s not a matter of changing processes or replacing materials. In this brand-new field, composite materials are quite clearly the way to go. This is an entire industry about to… well, take off, as manufacturers of battery-powered air taxis and delivery drones gear up to populate the skies of congested cities with zero-emissions flying vehicles.
And they need composites to be able to do that. “At current battery performances, lightweighting by means of high performance materials is crucial to reach range or payload targets,” explains Edoardo. “The weight of the vehicle’s structure, of its batteries and its payload all compete with each other for energy consumption. If you can lower structural weight through composites, you can gain more range or extra payload.”
Composite materials: the path to achieving net-zero aviation
Though issues such as the carbon footprint of raw materials and recyclability still need to be addressed, there is no doubt that the wider adoption of composites in aerospace is a necessary step towards its decarbonization. The aviation sector announced its aim to reach net zero-emissions by 2050, and is therefore looking at many ways to reduce its carbon footprint, including alternative propulsion technologies like hydrogen or electricity.
The adoption of sustainable aviation fuels (SAFs) will likely be the main contributor to that objective. “Everyone agrees on that, so there is a strong push to accelerate capabilities here,” says Stephen. “However, one thing is clear, no matter the vehicle or technology, composites will play a major role as lightweighting is critical for all.”
All in all, even if you set aside the quest for increased sustainability, working with more efficient aircrafts will continue to be an objective for this industry. “Lowering operational costs by consuming less and less fuel will always be a priority,” concludes Edoardo. “Also, improved aircraft designs will help increase efficiency even more; and in many cases, these designs are enabled by composites.”