The Composite Cycle Engine (CCE) concept incorporates piston engine technology into the core of an aircraft turbo engine. Assuming an entry into service in 2050, fuel burn improvements up to 50% relative to year 2000 turbofan technology (11% relative to year 2050 advanced GTF technology respectively) can be reached.

The piston engines increase thermal efficiency by using non-stationary isochoric-isobaric combustion, which enables higher peak pressures and temperatures within the core engine. In the current design, the piston engine is connected with the high pressure spool and powers the axial-radial high pressure compressor (dark blue). The low pressure system is similar to a conventional geared turbofan (GTF) architecture. This way, the outstanding power to weight ratio of low pressure turbines can be fully utilized and an ultra-high bypass ratio is realized.

System Details

  • Ultra-high bypass ratio Composite Cycle Engine technology
  • Piston engine powers high pressure shaft
  • No High Pressure Turbine
  • No power- and bleed-offtakes
  • Slim line nacelle design
  • Buffering volumes to reduce interaction of stationary operating turbo components and non-stationary piston engine

Geometry and Weights

Fan diameter        
Engine length     
Engine weight      
Piston engine weight    
Stage count        
Number of Fan blades        
Gear Ratio (Fan)       
Number of pistons        
Gear Ratio (Piston)     
Piston bore               
Piston stroke             
Piston vmean             
Piston Compression Ratio
2.87 m
5.88 m
7.27 t
2.45 t
0.2 m
0.2 m
18 m/s


Engine Design

Operating conditions 
Thrust (@TOC-MCL) 
TSFC (@Cruise)     
Burner exit temp. (@TOC-MCL) 
OPR (conventional)        
Peak pressure (@Take-Off)
Overall efficiency           
Intake mass flow rate

M0.82 / ISA+10 / FL350
49.7 kN (11.2 klbf)
11.5 g/kN/s (0.406 lb/lbf/hr)
1700 K
30 MPa
48.2 %
1100 kg/s





General Assembly Drawing

Simplified General Arrangement Sketch



The research leading to this Mock-up has received funding from the European Union's Horizon 2020 research and innovation programme under agreement No 633436, Project ULTIMATE (Ultra Low emission Technology Innovations for Mid-century Aircraft Turbine Engines).

Further Reading

Paper: A Composite Cycle Enginge Concept for Year 2050
Sascha Kaiser, Hagen Kellermann, Markus Nickl, Arne Seitz