According to Elon it’s simple, you need to get high really fast! The higher the better.
Elon Musk proposes a vertical take off and landing, supersonic electric jet with gimbaled thrust that can change direction just like a rocket. He envisions a lightweight flying wing design, with high energy density batteries structurally integrated into the craft. He says the battery cells would need to be as light as possible, and have an energy density of at least 400 wh/kg with a high cycle life.
Because air is very thick at sea level, and air density decays exponentially, Elon argues the true benefits of electric aviation will be reaped in the low air resistance of high altitude, where you’ll go faster for the same amount of power.
To Elon, Electric Planes really start to make sense if you can ascend to a high enough altitude where you can cruise without using too much energy. He further posits that for electric aircraft efficiency, you want to have a high bypass ratio and move a large mass of air slowly with a large propeller, so you can reduce the velocity component of kinetic energy.
He argues that jet engines are inefficiently designed because they have to operate at a wide range of altitudes, and the key advantage of electric is that it’s not ingesting air. So it’s not effected by the low air density of high altitudes.
As for a Tesla Electric Aircraft, he’s not ruling it out entirely, but says he’s got a bit too much on his plate right now to tackle the friendly skies.
While Elon Musk might dream of supersonic electric flight, this is likely a long ways off. We investigated in our research based documentary Electric Planes: They Have Arrived
We collaborated with a team of aerospace engineers, NASA scientists, and veteran pilots to sort through the current electric aircraft research and evaluate the most promising new technologies based on performance, practicality, and economics.
We’ll provide a comprehensive overview of electric airplane technology, discuss the benefits and challenges, and then rank the most revolutionary electric planes.