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eVTOL UPDATE PART 2
YESTERDAY IN PART 1, we looked at “The Battery That Flies,” Ben Ryder Howe’s article in The New York Times, April 16, 2022. Today in Part 2, we do a high soar (i.e., an aeronautic deep dive) of electric Vertical Takeoff and Landing aircraft in “Electric Planes: They Have Arrived, posted by Electric Future at YouTube, April 28, 2021.
ePowered Sailplanes. The image shows a modern ePowered sailplane, a perfect application of electric propulsion: Sailplane construction is super-light. And all the power that’s needed is a gentle takeoff and brief hunt for soaring thermals.
This reminds me of a Gmax project of mine, the 1938 Luton L.A.3 Buzzard. It was an ultralight, powered by a second-hand 35-hp V-twin Anzani from a Morgan trike.
eAviaton Basics. The Electric Future’s 43-minute YouTube “Electric Planes: They Have Arrived” is replete with tidbits from a wide variety of sources.
For example, it cites the tradeoffs of electric-propelled aircraft: There’s the inherent simplicity of an electric motor, especially when contrasted with the complexities of internal-combustion engines, piston or turbine, and their rigors of maintenance and inspection. Plus, compared with internal combustion operation, electrics are essentially silent.
Alas, there’s also the paucity of electric energy storage versus that of fossil fuels. A typical modern lithium-ion battery offers about 1 megajoule/kg of energy. Jet A fuel contains around 43 megajoules/kg.
Another contrasting tidbit: The combustion of fossil fuel lowers aircraft weight (and thus enhances range). A drained battery weighs as much as a fully charged one.
On the Other Hand. Electric Future cites a Rolls-Royce study of overall economics, including fuel costs and powertrain efficiency.
According to this study, the efficiency of an electric motor more than overcomes its price per kWh.
A VTOL 747? Electric Future offers an interesting VTOL tidbit: The Concorde SST had four engines producing a total of 152,200 lb./thrust in providing its Mach 2 cruising speed. By contrast, according to Electric Future, equipped with this power capability a Boeing 747 could lift like a helicopter.
The Future of eAviation. Cited by Electric Future, Norway has promised that by 2040 all its domestic flights must be electric. Forbes, March 11, 2021, amplified on this with “Norway’s Widerøe Could Fly This Rolls-Royce Electric Plane by 2026.” David Nikel wrote, “Powered by Rolls-Royce technology and designed by Italian firm Tecnam, this 9-seat aircraft is perfectly suited to the unique requirements of aviation in Norway.”
“Very short flights of 15-30 minutes,” Nikel says, “are commonplace in the Scandinavian country due to the mountains and fjords that dominate the landscape and make ground transport slow.”
Precisely the environment for eVTOL. ds
© Dennis Simanaitis, SimanaitisSays.com, 2022
Simanaitis Says 
Electric aircraft are in the same class with lead balloons. The energy density of batteries is almost two orders of magnitude smaller than jet fuel. That won’t change much, under the most optimistic projections.