Pratt and Whitney’s Michael Winter gave an overview of future plane engines. He noted that lithium ion batteries have lower energy density than goose fat and honey. Rechargable batteries are not that far off in terms of cost for energy compared to fuels.
The near and mid-term is larger and more efficient turbine engines.
Electric planes will require redesigning the airplane with distributed engines and more efficient airframes. A hybrid turbine-electric systems that might use batteries and a single jet engine to generate electricity for the motors.
Further airplane improvements can be expected beyond the 2020s. Dr. Rutherford said, depending on how aggressively the industry adopts other advanced technologies like open-rotor engines, which improve efficiency by eliminating the shroud that surrounds most jet engines, and aerodynamic modifications that smooth the airflow over surfaces to reduce drag.
Distributing the motors around the plane can also bring aerodynamic advantages. The position of the motors on the leading edge results in accelerated airflow over it, which increases lift at the low speeds of takeoff and landing. As a result, the wing can be made narrower, which improves efficiency at cruising speeds by reducing drag. An eventual airplane design using distributed propulsion may have leading edge motors only for takeoff and landing, and a single motor at each wingtip that would be used for cruising.
Small commuter electric planes
Small efficient electric planes with vertical takeoff and landing could be better options to achieve the functions and capabilites of the vision of flying cars. Big planes with turbines need big airports. Small electric planes could takeoff from a highrise, a driveway or parking lot and fly directly to your destination.
SOURCES – AIAA, New York Times