Leeham News and Analysis
There's more to real news than a news release.
Leeham News and Analysis
- Boeing defends 787, 777 against whistleblower charges April 17, 2024
- Dissecting Boeing CEO’s statement next new airplane will cost $50bn April 15, 2024
- Bjorn’s Corner: New engine development. Part 3. Propulsive efficiency April 12, 2024
- A350-1000 or 777-9? Part 2 April 11, 2024
- Pontifications: Boeing “transparency”–not so much. April 9, 2024
Bjorn’s Corner: New aircraft technologies. Part 23. Efficient flight speeds
By Bjorn Fehrm
July 28, 2023, ©. Leeham News: We touched on efficient flight speeds in Part 21, but it was focused on fuel efficiency and how new technologies require the airliner to fly at new altitude-speed combinations to maximise the fuel efficiency gains.
We now look at how to fly the airliner cost-efficiently, which is slightly different from how to fly it fuel efficiently.
Figure 1. The difference between lowest fuel burn speed (Mmr) and long-range cruise speed Mlrc. Source: Airbus.
Bjorn’s Corner: New aircraft technologies. Part 22. Engine characteristics.
By Bjorn Fehrm
July 21, 2023, ©. Leeham News: Developments in engines and airframe technologies require that future airliners are flown differently to maximize the technology benefit.
After looking at the consequences of new developments for the airframe, we now analyze what engine developments mean for how they will be sized and flown.
Figure 1. The RISE engine from CFM. Source: CFM.
Bjorn’s Corner: New aircraft technologies. Part 21. Changed flight profiles
By Bjorn Fehrm
July 14, 2023, ©. Leeham News: Developments in engines and airframe technologies require that the aircraft are flown differently to maximize the benefits.
We start by locking what changes in parasitic and induced drag mean for how airliners fly.
Figure 1. A Truss Braced Wing airliner shall fly higher. Source: Boeing.
Bjorn’s Corner: New aircraft technologies. Part 20. Efficient flying
By Bjorn Fehrm
July 7, 2023, ©. Leeham News: We explore different technologies in the series that can make our next-generation airliners more efficient and, thus, less polluting.
We have discussed developments of engine and airframe technologies, such as Turbofans versus Open Rotors and different airframe configurations to minimize drag and, thus, energy consumption.
When utilizing these developments to increase efficiency we must fly the aircraft in a different way depending on the technology.
And how we fly the aircraft is not only influenced by the factors we have discussed. We must consider factors at the airplane level, at the airliner operational level, and finally, at the airline fleet level.
Figure 1. The NMA concepts included dual aisle airliners. Source: Leeham Co.
Bjorn’s Corner: New aircraft technologies. Part 19. Supersonic drag
By Bjorn Fehrm
June 30, 2023, ©. Leeham News: In our discussions about the drag of an airliner, we now cover the most complex drag type, Wave drag, or the drag created when the air goes from subsonic to supersonic flow.
We will focus on the physical understanding of what’s happening as the math behind the drag calculation is complex.
Figure 1. The Concord is designed for low Wave drag. Source: BAC and Aerospatiale.
Bjorn’s Corner: New aircraft technologies. Part 18. Minor drags
By Bjorn Fehrm
June 23, 2023, ©. Leeham News: In our series about technologies that influence the efficiency of a new generation of airliners, we have covered the dominant drag of an airliner, air friction drag, and the second largest drag, induced drag, and what can be done about them. Now we look at Pressure drag and Interference drag.
We will finish with Transonic drag next week, which requires a full Corner to explain well.
Figure 1. The drag types that affect our airliners. Source: Leeham Co.
Bjorn’s Corner: New aircraft technologies. Part 17. Airframe with lower induced drag
By Bjorn Fehrm
June 16, 2023, ©. Leeham News: This is a summary of the article Part 17P. Airframe with lower induced drag. The article analyzes Boeing 737 MAX 8-sized airliners with Truss Braced Wings versus wings with folding wingtips and the standard MAX 8 wing. We use our Aircraft Performance and Cost model to get the drag data and overall efficiency improvement for the concepts.
Figure 1. Boeing concepts of a next-generation airliner with Truss Braced Wing. Source: Boeing.
Bjorn’s Corner: New aircraft technologies. Part 17P. Airframe with lower induced drag
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June 16, 2023, ©. Leeham News: This is a complementary article to Part 17. Airframe with lower induced drag. It discusses in detail the simulations we have done on a Truss Braced Wing, using our Aircraft Performance and Cost model to compare it to today’s wings and alternative future concepts.
Bjorn’s Corner: New aircraft technologies. Part 16. Airframe with lower induced drag
By Bjorn Fehrm
June 9, 2023, ©. Leeham News: This is a summary of article Part 16P. Airframe with lower induced drag. It discusses the Truss Braced Wing type of airframe that increases the practical wing span of an aircraft and thus reduces induced drag.
Figure 1. Boeing concepts of a next-generation airliner with Truss Braced Wing. Source: Boeing.