Leeham News and Analysis
There's more to real news than a news release.
Leeham News and Analysis
- Bjorn’s Corner: New engine development. Part 5. Turbofan design problems April 26, 2024
- Airbus 1Q2024 results: Airbus CEO: “A350 in-service experience drives positive reputation and orders” April 25, 2024
- A350-1000 or 777-9? Part 3 April 25, 2024
- Boeing CEO promises company is turning around…again April 24, 2024
- Solid start for stand-alone GE Aerospace despite cuts to LEAP output April 23, 2024
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.
What’s the Green aviation news at Paris 2023?
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By Bjorn Fehrm
June 22, 2023, © Leeham News: Every announcement from aircraft deals, OEM updates, or supply chain news now has the words Sustainable/Sustainability injected in every second sentence. It doesn’t matter what the subject is; if it’s about a gas-guzzling way of transporting people at supersonic or even hypersonic speeds or at the other end in an eVTOL which is only as fast as your car on a US highway.
What is the real news about making our air transport system less polluting behind this misuse of the buzzwords? You have to search behind the headlines and the announcements that you know will not turn the dial. Let’s tour the Paris Air Show 2023 and look at the real developments in Sustainability.
Figure 1. First flight of Universal Hydrogen’s DH8-300 with a hydrogen propulsion system on the starboard side. Source: Universal Hydrogen.
Summary:
- The waves of Green propulsion solutions with inflated claims have calmed down.
- It’s replaced with operationally usable solutions that deliver tangible emission gains.
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.
The Small Airliner Problem, Part 8. A battery-based airliner
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By Bjorn Fehrm
June 15, 2023, © Leeham News: In our series on fundamental costs factors that make up Cash Operating Cost, COC (Fuel, Maintenance, Airway/Airport fees, Crew costs), we have started analyzing if the size related cost factors also apply to green propulsion airliners and if the trends stay the same or change.
We use the Heart Aerospace ES-30 project as an example of a battery-based airliner with range extenders. Last week we developed the fundamental aero data for the aircraft with our Aircraft Performance and Cost model; now, we fly representative sectors and look at the energy and fuel consumptions compared to a similar-sized turboprop airliner.
Figure 1. The Heart Aerospace ES-30 hybrid 30-seat airliner. Source: Heart Aerospace.
Summary:
- There is a difference between what the theory says about aircraft range on batteries and how you have to fly in practice to keep battery costs down.
- The ES-30 has dual range-extending Turbogenerators. They get going more often and at a shorter range than advertised.
The Small Airliner Problem, Part 7. How affected are Green airliners?
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By Bjorn Fehrm
June 8, 2023, © Leeham News: We have analyzed the costs factors that make up Cash Operating Cost, COC (Fuel, Maintenance, Airway/Airport fees, Crew costs), and how these vary with different size airliners. The aim was to search for fundamental trends and if these disadvantaged a smaller airliner versus a larger one.
We found that a smaller airliner (we analyzed from 190 seats down to 9 seats) has structural cost disadvantages versus a larger model. The analysis was made with conventional gas turbine-propelled planes so as not to complicate the work. Now we introduce airliner types with green propulsion concepts and see if the trends stay the same or change.
Figure 1. The Heart Aerospace ES-30 hybrid 30-seat airliner. Source: Heart Aerospace.
Summary:
- We analyze the fundamental characteristics of a hybrid 30-seat airliner and compare it to the conventional airliners we characterized in the series.
- The negative cost trend for smaller airliners worsens for a battery or hybrid airliner.
Bjorn’s Corner: New aircraft technologies. Part 15. Airframe for lower Induced drag
By Bjorn Fehrm
June 1, 2023, ©. Leeham News: Last week, we examined ways to lower the dominant drag of an airliner, the air friction drag (Figure 1).
Now we look at the second largest drag component, the Induced drag, and how it can be reduced. We go through the fundamentals of the drag to understand how to affect it. Then we look at aircraft changes to reduce Induced drag and if these make sense on an overall aircraft efficiency level.
Figure 1. The drag components on a typical single-aisle airliner at cruise. Source: Leeham Co.
Bjorn’s Corner: New aircraft technologies. Part 14. Airframe for lower friction drag
By Bjorn Fehrm
May 26, 2023, ©. Leeham News: This is a summary of the article Part 14P. Airframe for lower friction drag. The article discusses in detail a Blended Wing Body (BWB) type airframe and how it reduces the wetted area and, thus, air friction drag compared to a conventional tube and wing airframe.
Figure 1. JetZero Z5 250 seat BWB jet concept. Source: JetZero.
Bjorn’s Corner: New aircraft technologies. Part 14P. Airframe for lower friction drag
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By Bjorn Fehrm
May 26, 2023, ©. Leeham News: This is a complementary article to Part 14. Airframe for lower friction drag. It discusses in detail the Blended Wing Body (BWB) type of airframe that shall reduce the airframe wetted area and thus air friction drag.