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 13. March 14, 2025
- Rolls-Royce’s remarkable turnaround March 13, 2025
- NASA hit by DOGE layoffs, office closures; Boeing’s X-66A R&D continues for now March 11, 2025
- Boeing faces three labor contracts expiring this year March 10, 2025
- Bjorn’s Corner: Air Transport’s route to 2050. Part 12. March 7, 2025
Bjorn’s Corner: Sustainable Air Transport. Part 20. Dimensioning the Fuel Cell system
By Bjorn Fehrm
May 20, 2022, ©. Leeham News: Last week, we looked at the principal parts of a Fuel Cell-based propulsion system. We need a fuel cell that converts hydrogen to electric power and then an inverter and electric motor that drives the fan, Figure 1.
The fuel cell system is the complicated and heavy part of this setup. Let’s look at how we size such a system.
Figure 1. The principal parts of a fuel cell propulsion system compared with other electric motor-based systems. Source: Leeham Co.
Bjorn’s Corner: Sustainable Air Transport. Part 19. Fuel Cell propulsion systems
By Bjorn Fehrm
May 13, 2022, ©. Leeham News: Last week, we looked at advanced developments for hydrogen-burning gas turbines.
Now we look at the alternative hydrogen-based propulsion system, which uses a Fuel Cell to convert the energy in hydrogen to electric power that drives motors to spin propellers or fans, Figure 1.
Figure 1. The principal parts of a fuel cell propulsion system compared with other electric motor-based systems. Source: Leeham Co.
Bjorn’s Corner: Sustainable Air Transport. Part 18. Advanced Hydrogen Gas Turbines
By Bjorn Fehrm
May 6, 2022, ©. Leeham News: Last week, we looked at how we create the shaft power for the thrust device we discussed before. We described the basics of a hydrogen-burning gas turbine alternative.
When we have liquid hydrogen as fuel, several advanced developments are possible. It’s what we look at now.
Figure 1. Airbus ZEROe hydrogen gas turbine concepts. Source: Airbus.
Bjorn’s Corner: Sustainable Air Transport. Part 17. Gas Turbine Propulsion
By Bjorn Fehrm
April 29, 2022, ©. Leeham News: Last week, we looked at the thrust generating device that aircraft propulsion systems use. We could conclude that independent of how we create the shaft power, we can choose different thrust technologies with desired characteristics. A propeller, open fan, or fan in nacelle covers different speed ranges and efficiency profiles.
Now we look at how we generate the shaft power for these devices. We start with the hydrogen-burning gas turbine alternative.
Figure 1. Airbus ZEROe hydrogen gas turbine turboprop concept. Source: Airbus.
Bjorn’s Corner: Sustainable Air Transport. Part 14. Propulsion system requirements.
By Bjorn Fehrm
April 8, 2022, ©. Leeham News: Last week, we discussed the architecture of a liquid hydrogen fuel system. We now start looking at the propulsion system of a hydrogen aircraft.
Before discussing how a propulsion system is done, we must understand what power requirements different airliner types have and the importance of these types in the market.
Figure 1. The World Jet market forecast for the next 20 years. Source: JADC.
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.
Bjorn’s Corner: Sustainable Air Transport. Part 11. Hydrogen and SAF.
By Bjorn Fehrm
March 18, 2022, ©. Leeham News: In our series, we have now seen the major limitations batteries as an energy source impose on an airliner and that hybrids work but don’t bring any advantages for an airliner.
The alternatives are to use an energy source with a higher energy density and combine it with an efficient propulsion system. Sustainable Aviation Fuel, SAF, has the same high energy density as today’s Jet fuel and hydrogen’s density is three times higher than Jet fuel.
Figure 1. The Volume and Mass densities of fuels. Source: Boeing.
Bjorn’s Corner: Sustainable Air Transport. Part 9P. Parallel Hybrid. The deeper discussion.
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By Bjorn Fehrm
March 4, 2022, ©. Leeham News: This is a complementary article to Part 9. Parallel Hybrid. It uses Leeham Company’s Aircraft Performance Model from our consultancy practice to analyze the design of a Parallel Hybrid aircraft for regional operations.
Our design brief is to make turboprop upgrade packages for De Havilland DH8-200,-300, and-400 aircraft. By using a Parallel Hybrid we could “target a 30% reduction in fuel burn and CO2 emissions, compared to a modern regional turboprop airliner” according to Pratt & Whitney Canada. Time to check if we can reach these levels.
Bjorn’s Corner: Sustainable Air Transport. Part 8. Serial Hybrids.
February 25, 2022, ©. Leeham News: This is a summary of the article Part 8P. Serial Hybrid, the deeper discussion.
We take an ES-19 type of battery aircraft and add a range extender to avoid the inadequate range we found in Part 6 and 6P.
Initially, it seems a good idea. We can use the benefits of the battery and then complement it with energy from the range extender. As you systematically work through the concept, the problems surface.
Figure 1. Serial Hybrid works for cars (Toyota Prius pictured), but not for aircraft. Picture: Toyota.
Bjorn’s Corner: Sustainable Air Transport. Part 6. Energy consumption.
By Bjorn Fehrm
February 11, 2022, ©. Leeham News: In a sister article, Part 6P. Energy consumption, the deeper discussion we use Leeham’s Aircraft Performance Model from our consulting practice to generate the aeronautical energy consumption for aircraft like Eviation’s Alice and Heart Aerospace’s ES-19.
This is the energy needed to combat the drag of the airframe during flight (Figure 1). We then add the losses in the chosen propulsion system to arrive at the energy drawn from the energy source.
Figure 1. Simplified force model for an aircraft. Source; Leeham Co.
