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Propulsion & Power

The UK must maintain world leadership in aircraft propulsion and power by developing the most efficient systems that lower environmental impact.

The development and manufacture of propulsion systems constitutes around 50 per cent of the sector’s direct economic activity in the UK, concentrated in large high-bypass turbofan engines for widebody passenger aircraft. High-bypass turbofans have delivered the greatest reduction in environmental impact of aircraft over the last 30 years. A diverse UK supply chain produces components and sub-systems for engines in almost market segments for domestic and overseas production and aftermarket services.

Market needs and environmental imperatives demand ever more efficient propulsion and power systems. The UK is well positioned to deliver these. A new generation of turbofan, turboprop and turboshaft engines will enter the market in the next five to 10 years. Electrification offers new routes to further improve environmental performance, ranging from batteries and fuel cells for smaller short-range aircraft and urban air vehicles, through hybrid turbo-electric propulsion for larger short- range aircraft, to electrification of the propulsion system for long-range aircraft.

Ensure the UK is at the forefront of delivering the next generation of low-emission ultra-high-bypass ratio (UHBR) turbofan engines

The next generation of UHBR turbofans will deliver a further 10 per cent in fuel efficiency and reduce noise. The UK must stay at the forefront of these developments to be a market leader, create a sustainable aerospace industry and secure the associated supply chain opportunities.

UHBR turbofans are aimed at making aircraft more efficient and quieter. The technologies to achieve this need to be demonstrated to technology readiness level (TRL) 6, in flight, by 2023 to be ready for market opportunities in the second half of the 2020s. There are formidable technical challenges to overcome in areas such as lightweight low-noise gear-driven composite fan systems, highly efficient multi-stage turbomachinery, lean-burn low NOx combustion, wall-cooled turbines and high-strength high-temperature materials. The aircraft integration challenges associated with these very large engines must also be overcome. These engines need to take advantage of bio and synthetic sustainable fuels when they become available. We will work with industry to secure the necessary capabilities and technologies to underpin this critical area of the UK’s future aerospace industry.

Leading hybrid gas turbine/electric propulsion systems

The UK must secure leadership of hybrid gas turbine/electric propulsion systems that have the potential to usher in the next wave of propulsion efficiency.

These systems have greater potential to reduce environmental impact than pure turbofans. In these systems, gas turbines drive generators which connect to and power propulsors, which can be distributed across an aircraft. This can actively enhance aircraft aerodynamics together with propelling the aircraft. Careful optimisation is required at the system and whole aircraft level to ensure efficiencies are not outweighed by higher weight and cost. For longer-range products, a more electric UHBR turbofan provides opportunities to deliver environmental benefits beyond those of the baseline architecture post 2030.

To make these ideas work, the efficiency and power density of electrical power systems must be improved. They will require electrical power systems to operate at several kilovolts at high altitude, a formidable problem necessitating innovative insulation solutions. Technical innovations are required to address thermal management of high-power electrical machines and power electronics. We will work with the developing UK and international community in this area to support the evolution of concepts, technologies, infrastructure and system level demonstration.

Leading all-electric battery and fuel cell propulsion systems

The UK must secure the new opportunities offered by all-electric propulsion systems through bringing the necessary component technologies together with appropriate research infrastructure to mature and validate solutions.

For shorter-range flight, particularly in cities, there is huge global interest in battery- and fuel cell-powered propulsion.  Battery powered systems are simple and cheap, but are limited by storage capacity, weight, thermal challenges and recharge times. Fuel cells offer potentially better energy density and refuelling characteristics. All-electric systems may involve many propulsors across the vehicle, providing back-up in the event of failure.  ATI will work with other UK initiatives to support technologies for higher power density battery packs, electronics and electrical motors, along with lightweight thermal management systems. In collaboration with industry, the ATI will support the development of technologies, supply chain expansion, research infrastructure, and system level demonstrations for fuel cells and batteries; critical research areas include power density, thermal management, hydrogen storage and electrical power delivery.


Propulsion and Power Roadmap


Reduce Cost: reduce waste, improved manufactoring productivity and better utilisation of resources / skills

Improve Energy Efficiency: improved propulsive efficiency through novel architectures

Meet Operational Needs with Greater Flexibility: resilient and efficently-maintainable propulsion and power systems

Protect the Environment: reducing CO2, NOx, nvPM, perceived noise, material usage and waste

Enhance Passenger Experience: reduce in-cabin perceived noise

Improve Safety: damage tolerance, intrusion tolerance, predictability, quality assurance

Targets (EIS)


CO2 (% margin / fuel burn, 2000 baseline): 20% reduction by 2025, 25% reduction by 2035

NOx (% margin relative to AEP6, 2000 baseline): 55% reduction by 2025, 65% reduction by 2035

Perceived Noise (Propulsion, relative to Chapter 3, LR2 average): 30 EPNdb cumulative reduction by 2025, 36 EPNdb cumulative reduction by 2035

Technology Priorities (TRL 6)

2020 - 2025 2025 - 2030 2030 - 2035+
  • Lightweight, low speed, low noise composite fan system
  • Next generation composite fan system optimised to gas generator
  • High pressure ratio, high efficiency gas turbine core
  • Variable pitch fan systems
  • Lean burn, low NOx combustion system
  • Variable area fan nozzle systems
  • Development of sustainable fuels
  • High stress, high temperature materials
  • Novel, variable thermodynamic cycles
  • Installation of large diameter UHBR system into short, slimline nacelle
  • Powerplant system integration
  • Adaptive control systems
  • Advanced integrated heat exchangers and thermal management systems
  • Integrated hybrid propulsion concepts
  • Advanced integrated hybrid propulsion concepts (BLI, distributed, embedded)
  • UK technology validation facilities for high power hybrid propulsion systems
  • Lightweight cryogenic, superconducting, high power systems
  • High power, high efficiency electrical machines and power electronics
  • Hybridisation of UHBR
  • High voltage electrical systems for operation in high altitude environments
  • Thermal management systems for electrical machines and power electronics
  • Integration of all electric propulsion systems in air vehicle concepts
  • Integration of fuel cell propulsion systems in air vehicle concepts
  • High power density battery power packs, power electronics and electrical motors
  • High efficient, safety critical fuel cell systems for propulsion
  • Lightweight thermal management systems
  • Energy recovery systems
  • Lightweight fan and propeller systems