Here's a fairly in-depth analysis of supersonic electric VTOL aircraft: https://github.com/gusgordon/electric_jet https://github.com/gusgordon/electric_jet tld

Here's a fairly in-depth analysis of supersonic electric VTOL aircraft: https://github.com/gusgordon/electric_jet https://github.com/gusgordon/electric_jet tldr; they become "practical" with a battery specific energy of around 1500 Wh/kg. However, if you just want to do a demonstration, they are practical now (as this post suggests).