Bjorn’s Corner: New aircraft technologies. Part 29. Detailed design

By Bjorn Fehrm

September 8, 2023, ©. Leeham News: We described the Preliminary design phase of an airliner development program over the last weeks. Now our project is transitioning into Detailed design.

It’s the most challenging part of the project as we now go from perhaps a thousand people involved at the OEM into tens of thousands and even more people at consultancies and suppliers.

 

Figure 1. A new airliner family development plan. Source: Leeham Co.

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Bjorn’s Corner: New aircraft technologies. Part 28. Alternative Preliminary design

By Bjorn Fehrm

September 1, 2023, ©. Leeham News: We described the Preliminary design phase of an airliner development program last week. One could say this was the classical way that aircraft projects conduct Preliminary design.

There is a different way that Conceptual and Preliminary design can be run. It’s more along the lines of pre-development of functions, as a reader commented on two articles back.

Figure 1. An alternative new airliner family development plan. Source: Leeham Co.

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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.

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Bjorn’s Corner: New aircraft technologies. Part 24P. Single or dual aisle fuselage?

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August 4, 2023, ©. Leeham News: This is a complementary article to Part 24. Single or dual aisle fuselage? It discusses in detail the drag and weight simulations we have done on different fuselage types for the next generation of “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?

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The reality behind the eVTOL industry’s hyperbole, Part 3.

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By Bjorn Fehrm

July 27, 2023, © Leeham News: We look at the promises that the VTOL industry has made in their Investor prospects and what the reality is as they come closer to Certification and present their production-level prototypes. We also analyze whether these capabilities will be the final level.

Today we go through the trickiest part of any electric aircraft or eVTOL, the batteries. They are large, very heavy, and the most difficult part to certify on the aircraft, as the battery is dangerous if not designed, produced, and managed correctly.

Figure 1. The Joby Aviation S4 production prototype. Source: Joby Aviation.

Summary:
  • The battery system of an eVTOL sets restrictions on the operational usefulness of the category.
  • The everyday operational utility of VTOLs is far from the industries’ claims.

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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.

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The reality behind the eVTOL industry’s hyperbole


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By Bjorn Fehrm

July 13, 2023, © Leeham News: We have done a deep dive series on the cost problems experienced by small airliners and how these make life difficult for alternative propulsion projects.

The eVTOL industry also faces problems, but here it’s more its own overinflated promises that rub. It’s the subject of our next deep dive.

We look at what the top OEMs promised in the past and what the reality is as they come closer to Certification.

When it comes down to it, what missions can be flown and what cannot? Are the missions that can be flown enabling a new industry?

Figure 1. The Joby production prototype as presented on 28th June. Source: Joby Aviation.

Summary:

  • Investor prospects promised Total Available Markets (TAMs) as large as $500billion with flights at up to 200 miles per hour to destinations hundreds of miles away
  • The reality is more profane. None of these promises hold water.

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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.

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The Small Airliner Problem, Part 9. Maintenance costs for battery airliners with range extenders

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By Bjorn Fehrm

June 29, 2023, © Leeham News: In our series on fundamental costs factors that make up Cash Operating Cost, COC (Fuel, Maintenance, Airway/Airport fees, Crew costs) for new Green airliners, we have analyzed the energy costs and now move on to the maintenance costs.

For a battery-based airliner with range extenders, it’s a complex mix of battery and gas turbine costs.

Figure 1. The Heart Aerospace ES-30 hybrid 30-seat airliner. Source: Heart Aerospace.

Summary:
  • The maintenance costs for a battery-based airliner are high. It’s the batteries that cost, not the electric motors.
  • Adding range extenders complicates the propulsion system and adds further costs.

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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.

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