Leeham News and Analysis
There's more to real news than a news release.
Leeham News and Analysis
- Bjorn’s Corner: Air Transport’s route to 2050. Part 25. June 6, 2025
- New RISE powerplant benefits from decades of GE research and development June 5, 2025
- Engine makers emphasizing durability, reliability June 4, 2025
- Boeing CEO: Lessons learned are key to certification of 737-7/10 and 777X June 2, 2025
- Digital twin is a key to JetZero’s hopes for Blended Wing Body entry June 2, 2025
Bjorn’s Corner: The challenges of hydrogen. Part 25. Auxiliary power
By Bjorn Fehrm
February 19, 2021, ©. Leeham News: Last week we discussed hydrogen aircraft propulsion and found a shaft power producing gas turbine was considerably more weight-efficient than a fuel cell powering an electric motor. Both had the same 55% shaft power efficiency.
Will a gas turbine APU burning H2 be the best choice for auxiliary power as well?
Figure 1. The Honeywell 131-9 APU for the Airbus A320. Source: Honeywell.
Bjorn’s Corner: The challenges of hydrogen. Part 24. Propulsion choice
By Bjorn Fehrm
February 12, 2021, ©. Leeham News: After covering the basics of fuel cells last week in our hydrogen airliner series, we now look at what type of system to choose for aircraft propulsion and onboard systems power.
We analyze the propulsion side this week.
Figure 1. A SAFRAN concept for a low emission airliner from its Clean Sky 2 presentation. Source: SAFRAN.
Bjorn’s Corner: The challenges of hydrogen. Part 23. Hydrogen fuel cells
By Bjorn Fehrm
February 5, 2021, ©. Leeham News: Last week, we started the discussion around fuel cells as a source of electric energy in airliners. We went through the principle and asked some vital questions.
Now we look at different types of fuel cells and for what applications these are suited.
Figure 1. The principle of a hydrogen fuel cell. Source: Airbus.
Bjorn’s Corner: The challenges of hydrogen. Part 22. Hydrogen fuel cells
By Bjorn Fehrm
January 29, 2021, ©. Leeham News: Over the last weeks, we looked at Center of Gravity (CG) problems with rear fuselage liquid hydrogen tanks as used in Airbus’ ZEROe turbofan airliner concept. We can conclude that the CG shift is manageable for a short-range aircraft (range below 2,000nm).
Now we spend the next Corners diving into hydrogen fuel cell technology and how it can benefit a hydrogen-fueled airliner.
Figure 1, The principle of a hydrogen fuel cell. Source: Airbus.
Bjorn’s Corner: The challenges of hydrogen. Part 20. Hydrogen airliner weight shift
By Bjorn Fehrm
January 15, 2021, ©. Leeham News: In last week’s Corner, we looked at how hydrogen consumed in the rear fuselage tanks of Airbus’ ZEROe concept affect the airliner’s efficiency.
Now we look at other aspects of the rear placement of the tanks.
Figure 1. Airbus ZEROe turbofan airliner. Source: Airbus.
Bjorn’s Corner: The challenges of hydrogen. Part 19. Hydrogen airliner weight shift
By Bjorn Fehrm
January 8, 2021, ©. Leeham News: In our Corner before Christmas we discussed the hydrogen tank placement at the rear of the aircraft for Airbus’ ZEROe concept turbofan aircraft.
We now calculate how the weight transfer when emptying the tanks in the rear affects the ZEROe’s efficiency.
Figure 1. Airbus ZEROe hydrogen turbofan airliner. Source: Airbus.
Bjorn’s Corner: The challenges of hydrogen. Part 17. Hydrogen airliner program
By Bjorn Fehrm
December 11, 2020, ©. Leeham News: We use this Corner to define the time table for our hydrogen airliner program and for what areas we need to conduct risk-reducing research before we embark on an actual design.
As we said in last week’s Corner, we aim to develop a hydrogen airliner for the heart of the domestic market after the COVID-19 Pandemic. It’s a 160 to 180 seat single-aisle turbofan driven airliner, using liquid hydrogen as the fuel.
Figure 1. Airbus ZEROe hydrogen-fueled airliner concepts. Source: Airbus.
Bjorn’s Corner: The challenges of Hydrogen. Part 16. A Hydrogen airliner
December 4, 2020, ©. Leeham News: To dig a level deeper into the challenges of hydrogen airliners, as a next step we design such a plane (on a high level), now that we have covered the basics.
It will make us traverse the fundamental design tradeoffs of such a design. Reflecting on what we discussed in Part 3, “The Application Space for a Hydrogen Airliner,” we focus on the single-aisle short-haul domestic market, Figure 1.
Figure 1. CO2 emissions per aircraft type and range flown. Source: EU Hydrogen Powered Aviation report.
Bjorn’s Corner: 737 MAX ungrounding, ANAC’s and EASA’s decisions
By Bjorn Fehrm
November 27, 2020, ©. Leeham News: After the lifting on the grounding order by the FAA, ANAC (Brazils regulator) followed in the week, and EASA issued its plans for public comment.
What are the differences in the ungrounding conditions, and what are the reasons for any differences?
Figure 1. Circuit Breaker placement for the 737 NG and MAX. Source: Leeham Co. and Flightdeck737.be
Bjorn’s Corner: 737 MAX ungrounding, the technical background
By Bjorn Fehrm
November 20, 2020, ©. Leeham News: This week’s big news is the lifting of the grounding of Boeing’s 737 MAX.
I wrote about the changes made to the MAX Wednesday and why I believe it’s safe. Let’s use our Corner space to walk through what I wrote about, but with a more technical angle.
Figure 1. 737 MAX nacelles (right) compared with 737 NG nacelles (left). Source: Boeing and Leeham Co.