Some interesting reading.
Overview of NASA Electrified Aircraft Propulsion Research for Large Subsonic Transports.
https://ntrs.nasa.gov/archive/nasa/c...0180000361.pdf
GRC3: Integration of Innovative Electrical Systems for Rotorcraft (pages 12 & 13)
http://cleansky.eu/sites/default/fil...eport_2015.pdf
But are helicopters the future?
http://evtol.news
Upcoming lecture by Nick Lappos.
https://vtol.org/news/lappos-selecte...olsky-lecturer
.