Thanks Nick,
I am trying to design an airplane with powered lift to allow flight at a lower speed only for takeoff and landing. The powered lift would only be used about 5 seconds or so. The efficiency is not important in this case I contend.
This is a lesson I learned when you were discussing the lack of efficiency of the Harrier jump jet. I think a Harrier test pilot said the Harrier only used about 100 lbs of fuel to make a landing. Sure the Harrier is not efficient in hover but that is not the mission. I also watched a C-130 equipped with 8 JATO rockets take off in a short distance and climb briefly very steep. JATO is not efficient for long haul but probably more efficient for just the needed 15 second thrust.
I think the future of personal VTOL aircraft is more likely to be fixed wing with brief powered lift. It's a different mission than a working helicopter that must hover for long periods.