Leeham News and Analysis
There's more to real news than a news release.
Bjorn’s Corner: Sustainable Air Transport. Part 49P. eVTOL production costs. The deeper discussion.
Subscription required
By Bjorn Fehrm
December 9, 2022, ©. Leeham News: This is a complementary article to Part 49, eVTOL production costs. It discusses the typical production costs of a certified eVTOL when produced in large quantities.
eVTOLs will be produced under aeronautical production certification conditions, using aeronautical grade material and system. Our production cost model predicts such costs, including learning curve effects for each material type.
The Economics of the 767 and A330 at Seven and Eight abreast
Subscription Required
By Bjorn Fehrm
Introduction
Dec. 8, 2022, © Leeham News: In a previous article, we started speculating what an NMA type of aircraft would look like based on a Boeing 767 cross-section. An airliner’s cross-section decides the design of a large number of parts in an airplane.
In essence, a fuselage is a tube with a constant cross-section where the constant parts are repeated framewise to form the fuselage. It’s finished with a tapering forward cockpit and a rear tapering empennage.
We now look at what could have been a passenger version of an NMA that would have used the Boeing 767 cross-section with adaptations. To understand its economic impact, we make a comparison where we take a standard 767-300ER, then modify it to an NMA type fuselage and compare it to the competition in the size class, the A330-200 and -800.
As before, we do this by flying the world’s busiest long-haul route, London Heathrow, to New York JFK.
Summary
- An NMA based on an improved 767 fuselage cross-section would have been a very competitive airliner
- I would be the ideal replacement for the Boeing 757, 767, and 787-8.
Bjorn’s Corner: Sustainable Air Transport. Part 40. VTOL mission.
By Bjorn Fehrm.
October 7, 2022, ©. Leeham News: Last week, we discussed the reality of mass fractions for certified aircraft. There is an abundance of statistics on projects that have gone through the arduous development and certification phase, which always turns out heavier than projected.
Using such statistics, we have a base from which to fly a typical hover and cruise eVTOL design and see what we get in terms of energy consumption and range.
Figure 1. The Vertical Aerospace VX4 in an early rendering with similar looks to the eVTOL we discuss. Source: Vertical Aerospace.
Bjorn’s Corner: Sustainable Air Transport. Part 36. Battery Management.
By Bjorn Fehrm
September 9, 2022, ©. Leeham News: Over the last weeks, we have discussed the cells that make up the battery system for an eVTOL.
The battery system has 10,000 cells or more. All these must, on an individual level, be managed to ensure they operate inside their allowed values. The Battery Management System, BMS, has this responsibility. It’s one of the most critical safety systems in an eVTOL.
Figure 1. The Battery Management System and battery packs from EP Systems. Source: EP Systems.
Bjorn’s Corner: Sustainable Air Transport. Part 33P. eVTOL batteries. The deeper discussion.
Subscription required
August 19, 2022, ©. Leeham News: This is a complementary article to Part 33, eVTOL batteries. It discusses the trickiest system on an eVTOL, the battery system.
While Lithium Ion batteries have come a long way since the electric flight ideas took off in 2015, the battery system is still the biggest challenge for eVTOL designers, not only for total energy content but for a range of parameters.
Bjorn’s Corner: Sustainable Air Transport. Part 32. Mixed architectures, Part 2.
August 12, 2022, ©. Leeham News: Last week, we looked at two eVTOLs that don’t fit the terminology we use; Multicopters, Vectored thrust, or Lift and Cruise, the Vertical VX4, and the Archer Maker. We look at Airbus’ CityAirbus NG this week, a Lift and Cruise design like no other (Figure 1).
Figure 1. The Airbus CityAirbus NG. Source: Airbus.
Bjorn’s Corner: Sustainable Air Transport. Part 25. High Temperature Fuel Cell-based 70-seat airliner
By Bjorn Fehrm
June 24, 2022, ©. Leeham News: Last week, we discussed how a High Temperature Fuel Cell (HTFC) could improve the installation of a propulsion system in our 70-seat airliner. We now add this variant to the systems we examined for installation effects and efficiencies.
The deeper discussion is in the sister article, Part 25P. High Temperature Fuel Cell-based 70-seat airliner.
Figure 1. The ATR 72-600 70-seater turboprop. Source: ATR.
Bjorn’s Corner: Sustainable Air Transport. Part 25P. High Temperature Fuel Cell-based 70-seat airliner. The deeper discussion.
Subscription required
June 24, 2022, ©. Leeham News: This is a complementary article to Part 25, High Temperature Fuel Cell-based 70-seat airliner. It adds the masses and efficiencies of a High Temperature Fuel Cell system to our 70-seat airliner fuel cell variants.
Bjorn’s Corner: Sustainable Air Transport. Part 23. Fuel Cell-based 70 seat airliner
June 10, 2022, ©. Leeham News: Last week, we looked at the different fuel cell systems that can go into a 70-seat airliner like the ATR 72. In this week’s Corners, we implement these in the aircraft and look at installation effects and efficiencies.
The deeper discussion is in the sister article, Part 23P. Fuel Cell-based 70-seat airliner.
Figure 1. The ATR 72-600 70-seater turboprop. Source: ATR.
Bjorn’s Corner: Sustainable Air Transport. Part 13. Hydrogen fuel system and APU.
By Bjorn Fehrm
April 1, 2022, ©. Leeham News: Last week, we looked at how to store hydrogen in an aircraft. We could see the gaseous storage of hydrogen is too heavy other than for demo systems and extreme short-haul. For practical airliners, liquid hydrogen is the solution.
Now we look at what this means for the aircraft fuel system and how to configure a suitable Auxiliary Power Unit, APU.
Figure 1. Typical placement of hydrogen tanks. Source: Leeham Co.