Leeham News and Analysis
There's more to real news than a news release.
Leeham News and Analysis
- The BWB has a long way to go before flying passengers, freight May 12, 2025
- Bjorn’s Corner: Air Transport’s route to 2050. Part 21. May 9, 2025
- Does an A220-500 need a new wing and engines? Part 2. May 8, 2025
- Embraer downplays tariff impact on 2025 results May 6, 2025
- JetZero readies effort for private equity fund raising May 5, 2025
Bjorn’s Corner: Air Transport’s route to 2050. Part 1.
By Bjorn Fehrm
October 18, 2024, ©. Leeham News: In Corners over the last years, we have covered new airliner technology and engine developments that would apply to the next-generation airliners in the largest segment of the market, the single-aisle segment, or as we like to call it, the Heart of the Market segment, as it’s not sure it will be a single-aisle aircraft.
The series has assumed this generation will be hydrocarbon-fueled gas turbine-propelled airplanes. Therefore, it has not covered the current state of alternatives to gas turbine-based hydrocarbon propulsion.
We will cover this now. We are now 10 years into the discussions and work of reducing Air Transport’s reliance on hydrocarbon fuels, which started in earnest when Airbus flew the E-Fan battery-electric aircraft at the Farnborough Air Show in 2014, Figure 1.
How are we doing?
Figure 1. Airbus E-Fan at Farnborough Air Show 2014. Source: Wikipedia.
Bjorn’s Corner: New engine development. Part 28. Wrapup.
By Bjorn Fehrm
October 11, 2024, ©. Leeham News: We have done an article series on why engine development takes longer than airframe development. Part of the reason is that advancements in engine technology can deliver considerably higher fuel consumption reductions than airframe advancements.
The change of engines for the A320 series and 737 MAX delivered a 15% improvement in engine efficiency. In contrast, the airframe improvement was less than half, mainly by stacking cabin seats closer together.
Figure 1. The 4:1 gear ratio Utrafan demonstrator in the Rolls-Royce test cell. Source: Rolls-Royce.
Bjorn’s Corner: New engine development. Part 26. New versus old, Trent 1000 vs. XWB
By Bjorn Fehrm
September 27, 2024, ©. Leeham News: We do an article series about engine development and why it has longer timelines than airframe development. It also carries larger risks of product maturity problems when it enters service than the airframe of an airliner.
In our look at examples of recent developments with problems and these put in a historical perspective, looking at the reliability and durability of its predecessor we compare the Rolls-Royce Trent 1000 for the Boeing 787 to the Trent XWB for the Airbus A350.
Figure 1. The Rolls-Royce Trent 1000 with its wide cord hollow titanium fan. Source: Rolls-Royce.
Bjorn’s Corner: New engine development. Part 25. New versus old, CFM56 vs. LEAP
By Bjorn Fehrm
September 20, 2024, ©. Leeham News: We do an article series about engine development and why it has longer timelines than airframe development. It also carries larger risks of product maturity problems when it enters service than the airframe of an airliner.
In our look at examples of recent developments with problems and these put in a historical perspective, we compare the CFM56 to the LEAP, comparing their reliability and durability.
Figure 1. The CFM56 with its mid-span shrouded titanium fan. Source: CFM.
Bjorn’s Corner: New engine development. Part 24. New versus old, GTF versus V2500
By Bjorn Fehrm
September 13, 2024, ©. Leeham News: We do an article series about engine development and why it has longer timelines than airframe development. It also carries larger risks of product maturity problems when it enters service than the airframe of an airliner.
We have covered the engine’s different parts and their technology challenges. We now look at some examples of recent developments with problems and put them in a historical perspective.
Bjorn’s Corner: New engine development. Part 23. Development risks.
By Bjorn Fehrm
September 30, 2024, ©. Leeham News: We do an article series about engine development and why it has longer timelines than airframe development. It also carries larger risks of product maturity problems when it enters service than the airframe of an airliner.
We have covered the parts of an engine that involve challenging technology and which decide its reliability (dispatch consistency) and durability (time on wing). Now, we discuss why modern engine design is more challenging regarding these parameters than airframe design.
Figure 1. The Pratt & Whitney GTF in cross-section, one of the new engines. Source: Pratt & Whitney.
Bjorn’s Corner: New engine development. Part 22. High Turbine technologies.
By Bjorn Fehrm
August 30, 2024, ©. Leeham News: We do an article series about engine development and why it has longer timelines than airframe development. It also carries larger risks of product maturity problems when it enters service than the airframe of an airliner.
We reached the turbine part on our way through the engine, where we last looked at high-pressure turbine temperatures. It’s the most stressed part of the engine and, in most cases, decides its durability. To understand why, we look closer at turbine technologies.
Figure 1. Our example engine, the LEAP-1A, is in cross-section with booster to compressor bleed valve area marked with a red circle. Source: CFM.
Bjorn’s Corner: New engine development. Part 21. The High Turbine.
August 23, 2024, ©. Leeham News: We do an article series about engine development and why it has longer timelines than airframe development. It also carries larger risks of product maturity problems when it enters service than the airframe. We discuss why.
In our journey through an engine, we have reached the turbine part, where we will dig deeper into the high-pressure turbine. This is the most stressed part of the engine and has a major influence on engine performance and durability.
Figure 1. Our example engine, the LEAP-1A cross-section with the high-pressure turbine marked. Source: CFM.
Bjorn’s Corner: New engine development. Part 20. Temperatures.
By Bjorn Fehrm
August 16, 2024, ©. Leeham News: We do an article series about engine development. The aim is to understand why engine development now has longer timelines than airframe development and carries larger risks of product maturity problems.
To understand why engine development has become a challenging task, we need to understand engine fundamentals and the technologies used for these fundamentals.
We have covered the different areas of a gas turbine except the exhaust (Figure 1). Before we go to the exhaust and the different outputs from a gas turbine Core, we look at the temperatures and how to cope with them in the different sections of a gas turbine.
Figure 1. The gas turbine cycle and its parts. Source: Rolls-Royce: The Jet Engine.
Bjorn’s Corner: New engine development. Part 19. Turbines.
By Bjorn Fehrm
August 9, 2024, ©. Leeham News: We do an article series about engine development. The aim is to understand why engine development now has longer timelines than airframe development and carries larger risks of product maturity problems.
To understand why engine development has become a challenging task, we need to understand engine fundamentals and the technologies used for these fundamentals.
We have covered the problem areas of (Figure 1) compression in the compressor and combustion. Now, we look at the power-generating section, the turbines.
Figure 1. The gas turbine cycle and its parts. Source: Rolls-Royce: The Jet Engine.