Leeham News and Analysis
There's more to real news than a news release.
Bjorn’s Corner: New aircraft technologies. Part 26. Airliner development program
By Bjorn Fehrm
August 18, 2023, ©. Leeham News: We started last week to look at how to make the development of a new airliner family more efficient.
First, we describe how development projects are phased and how many people with what competencies are engaged in each phase. Then we can start the discussion of what changes can be made and what would be the consequences.
Figure 1. The JetZero Blended Wing Body that USAF partially funds to prototype. Source: USAF and JetZero.
Bjorn’s Corner: New aircraft technologies. Part 25. Efficient development
August 11, 2023, ©. Leeham News: We have described a number of technological advances that can be used to make the next-generation airliners more efficient and, thus, more environmentally friendly.
Part of developing more efficient next-generation aircraft is to change the development process to be more efficient. The last Boeing aircraft, the 787, took 7.5 years from launch to entry into service, and Airbus A350 took 8.5 years.
The target is to reduce this by up to 50%, but how?
Figure 1. The Airbus A350 development schedule. Source: Airbus.
Bjorn’s Corner: New aircraft technologies. Part 24. Single or dual aisle fuselage?
By Bjorn Fehrm.
August 4, 2023, ©. Leeham News: This is a summary article to Part 24P. Single or dual aisle fuselage. It summarizes the drag and weight simulations we have done on fuselages for the next generation Heart of the Market airliners. When it comes to drag and weight for a 250-seat airliner that shall replace today’s Single Aisle, is a Single Aisle fuselage lower in drag and weight than a Dual Aisle fuselage?
Figure 1. The drag components of a Single Aisle airliner at 35kft and M0.78. Source; Leeham Co.
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.