Leeham News and Analysis
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Bjorn’s Corner: Sustainable Air Transport. Part 41. VTOL mission calculations.
By Bjorn Fehrm.
October 14, 2022, ©. Leeham News: Last week, we defined the phases of an eVTOL mission that shall show us the typical range and endurance of the eVTOLs of a hybrid vectored thrust/lift and cruise eVTOL, similar to a Vertical VX4, Figure 1.
Several parts of the energy consumption calculations are complex, and surprisingly it’s not the vertical parts. We go through why and how we calculate the energy consumed for the mission.
Figure 1. The Vertical Aerospace VX4 in an early rendering with similar looks to the eVTOL we discuss. Source: Vertical Aerospace.
Voltaero’s Cassio hybrid plane is “Mild”
The somewhat different hybrid-electric aircraft
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By Scott Hamilton and Bjorn Fehrm
Oct. 10, 2022, © Leeham News: A French company, Voltaero, is taking a different approach to the plethora of concepts to produce a “green” aerial vehicle.
The Cassio family of aircraft uses a Mild Hybrid to avoid the pitfall of most hybrids, the need for a large battery. Batteries of today and tomorrow are too heavy to serve as the main power source for an aircraft unless it’s a flight around the airport like for trainers.
Voltaero designed a clever hybrid scheme that allows electric flight where it matters and leaves a thermal engine to do the rest. The concept, called a “Mild Hybrid,” keeps the advantages of the electric flight mode without the disadvantages of short-range or an expensive operation.
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.
UPDATED: All-electric Eviation Alice takes 1st flight
By Bryan Corliss
Sept. 27, 2022 © Leeham News: The battery-powered Eviation Alice has flown for the first time.
The nine-seat aircraft, powered by twin electric propeller motors assembled by Eviation’s sister company, magniX, rotated up and took off into a sky hazy from forest fires shortly after sunrise in the Pacific Time Zone, a little after 7 a.m.
After takeoff the plane banked to the right, circled for eight minutes around Grant County International Airport in Moses Lake, then landed safely. The Alice reached an altitude of 3,500 feet.
The dawn flight was an important milestone for Eviation, magniX, and for battery-powered aircraft in general. The Alice appears to be the largest electric passenger aircraft to fly so far, larger than the two-seater Pipistrel Velis, which had its first test flight with passengers in Iceland last month. Tecnam and Rolls Royce teamed up to fly a four-seater P2010 with a hybrid electric engine in February.
Summary
- EIS is still years away, CEO says
- Eviation and magniX need batteries to get better
- Alice will evolve in interim
Bjorn’s Corner: Sustainable Air Transport. Part 38. Piloting the VTOL
By Bjorn Fehrm
September 23, 2022, ©. Leeham News: Last week, we looked into the hardware needed for the Flight Control System (FCS) of the eVTOLs in development.
We could see the redundancy of the FCS had to be extensive as the tricky hover to forward flight transition demanded a full-time Fly By Wire concept with no direct mode backup.
Yet the FCS hardware demands are not the main problem of a safe eVTOL FCS. The pilot interaction is. Not because it’s tricky. Because every project does it their way.
Figure 1. Pilot flying the Joby S4 simulator. Source: Joby Aviation.
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Bjorn’s Corner: Sustainable Air Transport. Part 37. VTOL Flight Control.
By Bjorn Fehrm.
September 16, 2022, ©. Leeham News: We discussed one of the critical systems for an eVTOL over the last weeks, the battery system, its cells, and its management system.
Another critical system for a VTOL is its Flight Control System (the FCS).
Figure 1. The Honeywell UAM FBW (Fly By Wire) triple channel computer. Source: Honeywell.
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.
ICAO report outlines steps to reduce aviation’s carbon output
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By BRYAN CORLISS
Sept. 5, 2022, © Leeham News: Saying the climate crisis now is at “Code Red for Humanity,” the UN-sponsored International Civil Aviation Organization is calling on nations and companies to increase their investments toward techniques and technologies that can reduce aviation’s climate impact.
It won’t be easy, ICAO said in its Environmental Report 2022, which was released in July.
The aviation industry will be one of the hardest to ween off carbon-based forms of energy, a recent report concluded.
“Scaling the production of sustainable aviation fuels (SAF) and other energy sources requires substantial investment and financial support from both fuel suppliers and governments on top of what would be needed for associated infrastructural changes,” the report said. “This is particularly important, considering that the drop-in fuels have the largest potential to reduce the overall emission from international aviation by 2050.”
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Bjorn’s Corner: Sustainable Air Transport. Part 35. Lilium battery cells.
By Bjorn Fehrm
September 2, 2022, ©. Leeham News: This is a summary of the article Part 35P, Lilium battery cells.
It discusses the requirement the Lilium jet principle puts on its battery cells and how this is solved, both with a slightly different cell type and with some operational adaptations.
Figure 1. The final Lilium VTOL configuration with 30 jets. Source: Lilium.
Bjorn’s Corner: Sustainable Air Transport. Part 35P. Lilium battery cells. The deeper discussion.
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September 2, 2022, ©. Leeham News: This is a complementary article to Part 35, Lilium battery cells. It discusses the requirement the Lilium jet principle puts on its battery cells and how this is solved, both with a modified cell type and with some operational adaptations.