Leeham News and Analysis
There's more to real news than a news release.
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 12. Hydrogen storage.
By Bjorn Fehrm
March 25, 2022, ©. Leeham News: Last week, we looked at the energy density by mass and volume for hydrogen and regular Jet fuel (Kerosene), Figure 1.
With this information, we now look at how these fuels can be stored in an aircraft.
Figure 1. The Volume and Mass densities of fuels. Source: Boeing.
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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 10. Where Hybrids work.
By Bjorn Fehrm
March 11, 2022, ©. Leeham News: After our articles about Serial Hybrids and Parallel Hybrids showed they were unsuitable for airliners, where do these make sense?
The obvious answer is for our stop-and-go cars (as we then can recover the brake waste energy). Still, there are aeronautical special cases where hybrids can bring advantages. Let’s look into these.
Figure 1. The variable angle of rotor blades. Source: FAA Helicopter Flying Handbook.
Bjorn’s Corner: Sustainable Air Transport. Part 9. Parallel Hybrids.
March 4, 2022, ©. Leeham News: This is a summary of the article Part 9P. Parallel Hybrid, the Deeper Discussion.
We look into the Pratt & Whitney, Collins Aerospace, and De Havilland project to create a Parallel Hybrid propulsion alternative for the Dash 8 turboprops.
The project “targets a 30% reduction in fuel burn and CO2 emissions, compared to a modern regional turboprop airliner” according to the Pratt & Whitney press release.
Figure 1. The Parallel Hybrid components of the project. Source: Pratt & Whitney video.
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 7. Hybrids.
By Bjorn Fehrm
February 18, 2022, ©. Leeham News: Having covered batterie-based electric aircraft in the last three articles, we now move to the next ideas to improve our aircraft’s efficiency and burn less carbon-based fuels, hybrids.
A word of caution first. The words Sustainable, Electric, and Hybrid are, because of their success in ground transportation, virtually a must in any news release from anyone involved in aviation these days. We will unveil what is behind all this and what is real and what’s Greenwashing.
Figure 1. The successful ground hybrid, Toyota Prius. Source; Toyota.
Bjorn’s Corner: Sustainable Air Transport. Part 6P. Energy consumption, the deeper discussion.
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By Bjorn Fehrm
February 11, 2022, ©. Leeham News: This is a complementary article to Part 6. Energy consumption. It uses the Aircraft Performance Model from our Consultancy practice to generate energy consumed data when we fly a typical airline mission for the first aircraft we analyze, the battery-based Eviation Alice and Heart Aerospace ES-19.
These represent what to expect for airliners that have chosen this energy storage principle.
Heart Aerospace ES-19. Source: Heart Aerospace.
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.