
Electric Airports - lochieferrier
http://lochief.com/2015/12/05/electric-airports/
======
chroma
This post seems completely divorced from reality. There are many overlooked
issues:

\- To hover, you need a thrust/weight ratio >= 1. Taking off vertically
requires an even higher thrust/weight ratio. A modern Boeing 737 has a
thrust/weight ratio of 0.15. So a comparable VTOL aircraft is going to need
engines ≈7x more powerful than current ones. But those don't exist. The most
powerful jet engine in the world (the 777's GE90-115B) can't lift a 737
straight up. An electric version? Forget about it. The best production
electric motors are almost two orders of magnitude less powerful than the
GE90-115B.

\- Hovering and vertical takeoff are fraught with safety issues. With multiple
engines, any failure creates a deadly thrust imbalance. You also have to avoid
vortex ring state. And while VTOL craft like helicopters can autorotate, it
takes a skilled pilot along with the right combination of velocity and
height.[1]

\- Landing on skyscrapers means you'll have to deal with higher winds than
near the ground. While you can orient the craft in any direction, wind is not
constant. Gusts and swirls from the skyscraper will make landing difficult.

I could see VTOL electric craft replacing helicopters, but passenger jets are
not going away any time soon. The physics just don't work out for larger VTOL
aircraft.

1\.
[https://en.wikipedia.org/wiki/Helicopter_height%E2%80%93velo...](https://en.wikipedia.org/wiki/Helicopter_height%E2%80%93velocity_diagram)

