Unlocking electric flight

Article by Adam Green, freelance journalist

Not if we fly, but how we fly

A world without flight is no longer feasible. Aviation underpins global connectivity, trade, and culture, and its benefits are too deeply embedded in society to abandon. Aviation accounts for 2.5% of global CO₂ emissions, with emissions rising faster than those from rail, road and shipping since 2000. The International Civil Aviation Organization has established a long-term aspirational goal of net-zero emissions by 2050, which it estimates will cost up to $4 trillion US. But the technologies that will underpin this transition are not yet ready to scale, and rapid innovation is essential to getting aviation targets on track while sustaining global travel networks. The challenge is not whether we fly, but how we fly.

Efficiency through manufacturing complexity is a key element of that challenge, and a cornerstone of Birmingham’s long-standing partnership with Rolls-Royce. This collaboration unites fundamental research with industrial-scale manufacturing capability to fulfil a long-term vision for aviation. With a strong track record of translating research into real-world impact, the University of Birmingham and Rolls-Royce are enhancing the performance of today’s engines and developing the technologies that will underpin future engine architectures, opening pathways toward the decarbonisation of flight.

Professors Nick Green and Paul Withey are focused on strengthening Birmingham’s expertise in the casting of high-temperature materials, a critical area for aero engine performance. The University’s High Temperature Research Centre (HTRC) is a design, simulation, and advanced manufacturing facility dedicated to accelerating product and process innovation in this space. The fundamental research is done through the ARCANE project (Advanced Research into Crystallographic Anisotropy and Nucleation Effects in Single Crystals). ARCANE focuses on lower technology-readiness-level research, representing earlier stages of commercialisation and helping to bridge the gap between science and industrial application.

Enhancing predictive modelling and defect control in single‑crystal turbine casting

The HTRC’s core expertise lies in investment casting, a precision manufacturing process for complex metal components, with the goal of producing turbine parts that can operate more effectively under extreme temperatures. Improving the efficiency of gas turbines is expected to play a major role in unlocking the decarbonisation of long-range flight. This will be through either sustainable aviation fuels or hybrid-electric architectures. In this latter case, engines drive generators to top up electrical energy throughout the flight, which dramatically reduces turbine size. However, both solutions require smaller features to be made, presenting new challenges in manufacturing capability and defect control. Specifically, Professors Withey and Green are addressing these challenges through research into single-crystal casting for high-temperature turbine components. Although these components are small, they contain vast numbers of atoms. If these atoms do not all align then grain boundaries and anomalous structures tend to form. When the material is put under load at high temperature, stress localises and intensifies at these boundaries, accelerating deformation and failure. Eliminating those boundaries is therefore critical.

“If you can eliminate grain boundaries, you eliminate a substantial part of the deformation mechanism that leads to failure during long-term, high-temperature loading,” says Professor Green. “To do that, we need to process the metal from a liquid to a solid in a way that grows a single crystal from the liquid.” Once formed, these single-crystal parts must be complex enough to withstand even higher temperatures, allowing more heat to be extracted and rejected without risking melting.

Currently, predictive tools are not sufficiently advanced to quantify many of these defects during manufacturing; problems are often identified only at the very end of the process. “By the time you discover a blade is scrap, you may already have invested a lot of money in it,” says Professor Withey. By improving the control and prediction of defect formation during casting, researchers at the HTRC aim to reduce scrap, costs and capacity losses. “Small-scale facilities allow us to explore discovery science and proof of concept, but the ambition of HTRC is to get to the point where there are clear pathways to deployment and implementation,” says Professor Green. “The technologies being researched, and the products developed from them, can go all the way up into Rolls-Royce’s flying test bed.”

From innovation to implementation: driving the development of UltraFan

At the end of that pipeline is UltraFan, Rolls-Royce’s demonstrator aero engine, which integrates all the technologies underpinning its future engine architecture. At the hot end of the engine, where energy is generated to produce thrust, the high-temperature research conducted at the HTRC is essential. “Whether we’re talking about decarbonisation through hybrid systems or sustainable aviation fuels, the fundamental challenge is similar,” says Professor Withey. “Engine efficiency depends on how hot we can run the engine without needing excessive cooling. The hotter it runs, the more efficient it becomes.” At present, turbine components operate at temperatures hundreds of degrees above their melting point, in extremely aggressive environments. To survive, they rely on coatings, advanced materials and complex cooling systems. Cooling, however, comes at a cost to efficiency, so the ability to withstand higher temperatures improves engine performance.

Professor Green’s work on novel cooling designs aims to minimise the air required while preventing heat from entering the component in the first place. “The big thrust for future technologies is to stop heat entering the component and reject it back into the hot gas stream before it has a chance to melt the part,” he explains. “This also allows us to make ever more complex and smaller parts that continue to enhance the effectiveness of those cooling systems.” Components used in the UltraFan demonstrator engine were developed and manufactured within the HTRC. This is a measure of the strong commitment and collaboration that exists between the University of Birmingham and Rolls-Royce. “These are some of their most closely guarded and valued technologies, so it’s a great privilege for us, and a measure of the commitment that exists within the partnership,” says Professor Withey.

The partnership spans fundamental research, training, capability acquisition, fast make and demonstrator components, and improving existing manufacturing infrastructure. “The Rolls-Royce partnership really hinges on the ability to do industrially relevant research at pace,” says Professor Green. “It moves from knowledge of what’s going on in the world, to defining future science problems, to research, right through to innovation. It’s very rare to have an environment where you can cover all of those levels.”

Inside the Rolls‑Royce and University of Birmingham Research Partnership

Although Rolls-Royce and the University of Birmingham have been collaborating since 1989, the current phase of the partnership began with funding from the Higher Education Funding Council for England (HEFCE). “To ensure a long-lasting impact, HEFCE required the infrastructure to be underpinned by industrial commitment to show its relevance and value,” says Professor Green. “For every pound they put into a partnership, they expect two pounds to come in from the industrial partner.” Rolls-Royce invested £40 million alongside a £20 million commitment from HEFCE’s UK Research Partnership Investment Fund to establish the HTRC.

“The ambition is to be able to plug in a researcher, a student, or a postdoc and do very early-stage discovery, all the way through to influencing components that Rolls-Royce manufactures,” says Professor Green. “The role of the centre in training the future leaders in these technologies is very important.” The HTRC brings together designers, engineers, and researchers across disciplines including chemical engineering, mechanical engineering, and computer science, fostering open exchange of knowledge between academia and industry. “Rolls-Royce needs technologies that are ready now, but it also knows it can’t afford not to do this fundamental research, because we can’t get technologies for the future without it,” says Professor Withey.

The impact of this partnership has been formally recognised through the award of the Queen’s Anniversary Prize, the UK’s highest honour in education, for its contributions to transforming the aerospace industry, strengthening advanced manufacturing capability, developing world-class infrastructure, and creating highly skilled jobs. “The prize was a major milestone for us,” says Professor Green. “It recognised that the long-standing partnership and training activity extends well beyond our individual labs; it reaches across the wider department, and the breadth and strength of that relationship should be emphasised.”