[dcb]

re: 140 miles
per FAR 91.151, planes cannot take off without 45 minutes reserve flying time beyond their destination at night (30 @ day but we should look at worst case). That is for VFR. So assuming the lower limit of 90 minutes flight time (@ 70mph) you should plan on being at your destination within 45 minutes of flying, even if you are landing where you started. So that you could go 26 miles out and 26 miles back if you leave late in the day. Even if you assume 30 minutes reserve for daylight and VFR, that is still 60 minutes on the inside of flying time or 35 miles out and 35 back. Forgive my hyperbole of 10 miles.

I understand the local applications of this, and there is certainly some envelope of operation where it could make sense, but it is competing directly with potentially more efficient/affordable ground transportation at these distances, not for commuting in the general sense certainly.

But I am very concerned that john Q. public (and the folks looking for startup money) will not understand those limitations and think that we are on the verge of replacing all liquid fueled aircraft with batteries. 99.9999% of the public thinks of airliners when they think of airplanes, and of closing large distances in a small amount of time, because that is what they use when they buy passage on an airplane.

I also appreciate the reliability/durability concerns, and I hope that brushed motors are not on the table for the same reason. But a turboshaft could close the gap fairly well too and still offer high energy/weight and high energy/volume, both of which equate to more payload for way more miles.