Bjorn’s Corner: Sustainable Air Transport. Part 26. VTOLs.

By Bjorn Fehrm

July 1, 2022, ©. Leeham News: Last week, we finished our discussions around Fuel Cell-based airliners using hydrogen as fuel.

We could see the technology has true zero emissions, but the maturity of the many parts needed (hydrogen tank and fuel system, multi-MegaWatt class aeronautical fuel cells, motors, and controls) are not there. We are in the crawling before walk stage with sub-MegaWatt systems to make their first flights over the next years.

Another area claiming Green credentials is the VTOL space. Because these are based on electric technology, VTOLs are claimed as environmentally friendly and a good way to transport people.

We will analyze this industry and its claims of being an efficient, environmentally friendly way of transportation.

Figure 1. Joby S4, the VTOL project that has come the furthest. Source: Joby Aviation.

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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.

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Bjorn’s Corner: Sustainable Air Transport. Part 25P. High Temperature Fuel Cell-based 70-seat airliner. The deeper discussion.

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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.

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Bjorn’s Corner: Sustainable Air Transport. Part 24. High Temperature Fuel Cells

By Bjorn Fehrm

June 17, 2022, ©. Leeham News: Last week, we looked at the installation effects and efficiencies of the fuel cell systems we discussed in earlier parts of the series.

We could see the variants were significantly heavier than the propulsion system they would replace for an ATR72 size aircraft. The discussion assumed classical PEM fuel cells, also called Low Temperature PEM Fuel Cells. Now we look at if High Temperature PEM Fuel Cells can improve the installation situation.

Figure 1. The ATR 72-600 70-seater turboprop. Source: ATR.

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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.

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Bjorn’s Corner: Sustainable Air Transport. Part 23P. Fuel Cell-based 70-seat airliner. The deeper discussion.

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June 10, 2022, ©. Leeham News: This is a complementary article to Part 23, Fuel Cell-based 70-seat airliner. It analyses the masses and efficiencies of a 70-seat airliner equipped with the fuel cell-based propulsion systems we analyzed last week.

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Bjorn’s Corner: Sustainable Air Transport. Part 22P. Fuel Cell system efficiency and mass. The deeper discussion.

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June 3, 2022, ©. Leeham News: This is a complementary article to Part 22, Fuel Cell system efficiency and mass. It analyses the power, loss, mass, and efficiency consequences of the different fuel cell architectures described in the main article.

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Bjorn’s Corner: Sustainable Air Transport. Part 21. Fuel Cell system design

By Bjorn Fehrm

May 27, 2022, ©. Leeham News: Last week, we looked at the power levels we need in a fuel cell and electric motor system. We listed the required powers and durations for takeoff, climb, and maximum continuous power levels for a 70-seater turboprop.

Now we go deeper into the fuel cell system design, looking at system powers and thermals.

Figure 1. The principal parts of a fuel cell propulsion system. Source: NASA.

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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.

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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.

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