Zero emissions propulsion

We are not just witnessing the dawn of a new aerospace era focused on zero-emission flight, at GKN Aerospace we are making it a reality.

We know that no single system or technology will deliver the level of change required to achieve and ultimately surpass global emissions targets. This is why we are working with airports, airlines, aircraft OEMs, academia and supply chain partners to research and develop a suite of bold, game-changing technologies.

Although GKN is not an aircraft OEM, we develop notional aircraft concepts to help us understand and re-imagine structures and systems for future generations of aircraft. We use these concepts to explore the requirements of future aircraft, and use these requirements to drive the development of realistic solutions that will have a lasting impact on our industry and society.

As a major Tier 1 supplier of composite and metal airframe structures, gas turbine technology and electrical wiring systems to name but a few, GKN Aerospace is well placed to understand the potential risks and opportunities that arise with major changes such as the introduction of Hydrogen Electric Propulsion (HEP), hydrogen combustion or associated changes such as ‘dry wing’ architectures that no longer store fuel in the wings.

Hydrogen Electric Propulsion is typically considered a bigger departure from aerospace norms, but fuel cell technology could offer ground-breaking opportunities to achieve zero CO2 emissions, zero NOx emissions and mitigate contrails via smart venting systems. With respect to aerospace propulsion, the technology is in its infancy, but could achieve unprecedented levels of fuel efficiency and enable new system configurations that give OEMs attractive alternatives for how on-board power is generated and managed.

Moving the Dial
Addressing big challenges, such as climate change, requires big ideas and great collaboration. GKN Aerospace collaborates across a diverse ecosystem, and leads major research and development partnerships such as H2GEAR, which is supported by the UK Aerospace Technology Institute. These partnerships are critical for maturing the enabling high-performance technologies that will make our zero emissions aircraft vision a reality.

One key goal for GKN Aerospace is to invest in technologies that really ‘move the dial’ on emissions. Moving the dial means applicability at scale – it is not enough to deliver technology that only works on a small portion of the overall fleet. In order to ensure we are investing in technologies that scale well, we conduct trade studies to understand how different system architectures, subsystem types and operating efficiencies play out over different aircraft size classes and mission profiles.

When we began H2GEAR, we believed a 19 passenger variant would be manageable, but scaling Hydrogen Electric Propulsion technology for larger aircraft would be considerably more challenging. Less than 18 months into the programme, we can see a route to 48 passenger, 96 passenger and potentially larger aircraft within the next two decades.

One interesting concept is a 48 passenger zero emission regional aircraft. Our trade studies indicate that with a GKN liquid hydrogen fuel system, fuel cell power system, optimised electrical network and cryogenic motor drive technology, this 48 passenger concept would have a range of 934 nautical miles (covering about 99.9% of turboprop routes and about 90% of the regional jet market*). The aircraft would have zero CO2 emissions and zero NOx emissions, the only by-product would be water. Contrails, which can form when moisture is ejected from an aircraft, would be mitigated with a GKN smart venting system. A low noise electrical fan module would deliver lower noise pollution compared with an equivalent kerosene powerplant.

One of the key challenges for Hydrogen Electric Propulsion systems is thermal management. Fuel cell based systems are not able to reject the vast majority of waste heat into the exhaust stream in the same way that gas turbines do. Technologies that enable heat to be efficiently dissipated or utilised, without adding excessive drag or mass to the aircraft, are essential.

Improving the intrinsic efficiency of the fuel cells, along with the integration of GKN’s cryogenic motor drive, and cryogenic electrical network technologies, contributes significantly to mass reduction of the overall system.

Trajectory
GKN Aerospace seeks to be the most trusted and sustainable partner in the skies, supporting our OEM customers with world leading capability that will really move the dial on emissions. Our plans for zero emission aircraft technologies will deliver full ground based demonstrations in the 2025-2026 timeframe, with a view to delivering flight demonstration, with partners, shortly after. More will be revealed in the coming months and years.

 Footnote:
*ATI FlyZero Market Forecast & Strategy Report