Similarly, helicopters can autorotate, using the unpowered rotor to generate enough lift to make a controlled descent and landing.Д®VTOLs typically rely either entirely or in large part on distributed propulsion systems-many small electric motors driving propellers or fans that together generate lift. An airplane can rely on its wings to provide lift even if it has no operational engines, and in several cases large passenger airliners with multiple engine failures have been able to make controlled long-distance glides to land safely. But none of these eVTOL platforms are yet certified to carry passengers, and as a fundamentally different approach to flight, there are still open questions about safety.ДЄ significant difference in safety that separates many eVTOL designs from traditional aircraft (namely, airplanes and helicopters) is that eVTOLs often don't have a good way of passively generating lift in the event of a power system failure. American Airlines has ordered 250, with an option for 100 more. These concepts and prototypes, representing well over a billion dollars of venture capital investment in 2020 alone, promise that sometime in the near future, point-to-point travel between suburbs and urban centers will happen by air using innovative new flying vehicles that are fast, quiet, clean, and far more affordable than a helicopter. Electric vertical take-off and landing (eVTOL) aircraft for urban commuting are currently under development by more than a dozen different companies.

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