Leeham News and Analysis
There's more to real news than a news release.
Leeham News and Analysis
- A321neo continues upward market share; good luck hitting rate 14/mo for the A220 January 20, 2025
- Bjorn’s Corner: Air Transport’s route to 2050. Part 5. January 17, 2025
- What’s the future of the Boeing 787-8? January 16, 2025
- FAA understaffing affects air operations oversight; NTSB falls short, too January 13, 2025
- Bjorn’s Corner: Air Transport’s route to 2050. Part 4. January 10, 2025
Bjorn’s Corner: New engine development. Part 16. Compressor air use.
By Bjorn Fehrm
July 19, 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 a compressor and how these achieve power-to-air-pressure conversion efficiencies of over 90% by using advanced 3D airflow modeling. Now, we look at the users of the air from the engin’s compressor.
Figure 1. The gas turbine cycle and its parts. Source: Rolls-Royce: The Jet Engine.
To what extent can the A321XLR replace the Boeing 757, Part 3
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By Bjorn Fehrm
July 11, 2024, © Leeham News: We are comparing the Airbus a321XLR to the Boeing 757 to understand to what extent it can replace the 757 on the longer routes it operates for major airlines like United, American, and Delta.
We have looked at the development and operational history of the aircraft, their Apples-to-Apples capacity and range. Now, we use Leeham’s Aircraft Performance and Cost Model (APCM) to compare the operational costs of the aircraft.
Summary:
- The Boeing 757-200 has the same passenger capacity as the A321LR/XLR and a larger cargo capacity.
- Its range can compete with the A321LR but not the XLR. Both beat the 757 on operational economics.
Bjorn’s Corner: New engine development. Part 14. The compressor problems.
By Bjorn Fehrm
July 5, 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 covered the basics of how a compressor works last week. Now, we look at the challenges in compressor design (there are plenty).
Figure 1. The gas turbine cycle and its parts. Source: Rolls-Royce: The Jet Engine.
Bjorn’s Corner: New engine development. Part 13. The compressor.
By Bjorn Fehrm
June 28, 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 need for the axial speed of the core air to decrease and increase depending on the needs of the core engine’s sections. Now, we will start to look at the different parts of the core in more detail. We start with the compressor.
Figure 1. The gas turbine cycle and its parts. Source: Rolls-Royce: The Jet Engine.
Trent 7000 reliability under the spotlight
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By the Leeham News Team
June 24, 2024, ©. Leeham News: The Rolls-Royce Trent 7000 is the exclusive engine for the A330neo and the seventh in Rolls Royce’s Trent series.
Having entered into service in early 2019, the engine has already surpassed one million flying hours.
The powerplant – which is the Trent 1000 but with bleed air features vs the electrically-based Trent 1000 – features efficient hollow Titanium fan blades enabling a fuel burn improvement of 14% per seat compared to previous iterations of the A330.
Launched by Airbus in July 2014, the A330-900 Neo is powered exclusively by Trent 7000 engines. Credit: Airbus
However, there have been issues relating to the reliability of the Trent 7000 which have complicated the A330neo’s early years of service.
Industry insiders have told LNA that operators of the A330neo faced lower than expected time-on-wing for the powerplants, as well as a lack of spares that has impacted maintenance and return to service.
Experts say the protective coatings on the engine’s turbine blades have reportedly been a factor.
But RR strongly denies there have been any reliability issues with the engine.
A RR spokeswoman said: “Our fleet of Trent 7000 engines is performing exceptionally well, and has delivered industry-leading levels of reliability to our customers over the last 18 months.” Read more
Bjorn’s Corner: New engine development. Part 11. Core cycle.
By Bjorn Fehrm
June 14, 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 main thrust-generating device, which we can call a propeller, fan, or open rotor, depending on the application. To drive the main thrust device, we need a lot of shaft power, which is provided by the core. We start with how the core, which is a gas turbine, generates power.
Figure 1. The core cycle compared to a piston engine cycle. Source: Rolls-Royce, The Jet Engine.
A350-1000 or 777-8? Part 2
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By Bjorn Fehrm
May 16, 2024, © Leeham News: We are doing an article series comparing the capabilities of the Airbus A350-1000 and the Boeing 777X. We have looked at the A350-1000 versus the 777-9 and started comparing the history and capabilities of the 777-8 versus the A350-1000 last week.
Now, we use our Aircraft Performance and Cost Model (APCM) to fly the aircraft on a typical route and compare their performance.
Summary:
- The A350-1000 and the latest 777-8 definition is a closer payload-range match than the A350-1000 and 777-9.
- Passenger and cargo capabilities are similar. The economic comparison will be determined by maintenance costs for the engines.
A350-1000 or 777-9? Part 4
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By Bjorn Fehrm
May 2, 2024, © Leeham News: We are doing an article series comparing the capabilities of the Airbus A350-1000 and the Boeing 777-9. We looked at the development history of the aircraft and then their capability and fuel economics.
We could see that the 777-9 is trailing the A350-1000 in payload range, partly because we compare the base version of the 777-9 with a further developed A350-1000. Now, we investigate what the 777-9 performance would be should we include a typical future development of the Maximum TakeOff Weight (MTOW).
Summary:
- The A350-1000 has a clear payload-range advantage over the standard 777-9.
- With an in-service Maximum TakeOff Weight (MTOW) development like the A350-1000, the difference is reduced.
Bjorn’s Corner: New engine development. Part 5. Turbofan design problems
By Bjorn Fehrm
April 26, 2024, ©. Leeham News: We do an article series about engine development. The aim is to understand why engine development now dominates new airliner development when it comes to the needed calendar time and risks.
To understand why engine development has become a challenging task, we need to understand engine fundamentals and the technologies used for these fundamentals.
We discussed geared versus direct-drive turbofans last week. Now, we’ll examine some design problems for these engines.
Figure 1. The Pratt & Whitney PW1100G geared turbofan, with its unique aluminum fan. Source: Pratt & Whitney.
A350-1000 or 777-9? Part 2
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By Bjorn Fehrm
April 10, 2024, © Leeham News: We are doing an article series comparing the capabilities of the Airbus A350-1000 and the Boeing 777-9. The A350-1000 has not been a hot seller, and a lot of analysts asked why. Is there a capability gap or what is the reason?
At the same time, the reworked Boeing 777X had reassuring initial sales at the November 2013 launch at the Dubai Air Show, where Emirates ordered 150 777-9 out of a total show orderbook of 259 aircraft for Emirates (150), Qatar (50), Lufthansa (34), and Ethiad (20). The orders have since grown to 481 as of late 2023.
The A350-1000 has had a recent resurgence in orders and switches from the A350-900 orders, whereas the 777–9 has seen several delays due to engine and certification problems and is now scheduled for 2025 delivery instead of 2020.
Does the 777-9 or the A350-1000 hold the upper hand in a long-term race between the largest widebodies after the Airbus A380 and Boeing 747-8i stopped deliveries? We use our Aircraft Performance and Cost model to compare the two to understand their present performance and potential for upgrades.
Summary:
- The Boeing 777-9 is a larger and heavier aircraft with a 12% higher passenger capacity.
- Does an advanced wing and later generation engines compensate for an older and heavier fuselage structure?
