That all sounds about right, except for the generation part (see below) which is but a minor factor anyway.
Indefinite solar-powered flight is understandably not a goal of Pipistrel for this craft; it will be interesting once it gets to the point where it’s a more commercially feasible design goal.
I love how you rounded up to 1kW/m² to get a nice round number, then multiplied by 13.9!
It’s worth noting on the propeller generation point that it’s going to be more efficient not to use it if you’re trying to maximise range: it will diminish your glide ratio; it’s mostly for when you actively want to go down, and might as well retrieve and store most of the lost kinetic energy. If the Trainer gets 17:1, I’d expect the Electro would get roughly that 17:1 if merely idling, but lower if regenerating; I don’t care to speculate on the numbers—I’m not a pilot or an electric car expert and it’ll take me too long to calculate the actual energy rates involved. But physics more or less decrees that it can’t regenerate more power than it will take to regain the additional lost altitude. (I say only “more or less” because of things like gravity assist manoeuvres, which are fascinating but not applicable to craft like this.)
I was rather sloppy in the way I brought the regeneration up in my earlier comment. It was true, but not relevant because of this last paragraph. I didn’t think it through when I mentioned it at first.
Agreed. It is probably too generous to assume the ideal glide ratio and simultaneously assume generation via the prop.
Depends on a lot of stuff though. It's not a question of energy creation -- the energy of the system includes energy in the air. Generally freewheeling generates more drag than a stationary propeller (google "ESC brake vs freewheel" to see what R/C hobbyists have to say about this). However, you may have an unusual situation where maintaining the ideal glide velocity requires braking, and in such a case it is presumably more efficient to brake via the propeller.
Suffice it to say that even in the ideal case, this particular aircraft would have trouble maintaining flight via solar power, but other aircraft are proving that this is a viable possibility.
Indefinite solar-powered flight is understandably not a goal of Pipistrel for this craft; it will be interesting once it gets to the point where it’s a more commercially feasible design goal.
I love how you rounded up to 1kW/m² to get a nice round number, then multiplied by 13.9!
It’s worth noting on the propeller generation point that it’s going to be more efficient not to use it if you’re trying to maximise range: it will diminish your glide ratio; it’s mostly for when you actively want to go down, and might as well retrieve and store most of the lost kinetic energy. If the Trainer gets 17:1, I’d expect the Electro would get roughly that 17:1 if merely idling, but lower if regenerating; I don’t care to speculate on the numbers—I’m not a pilot or an electric car expert and it’ll take me too long to calculate the actual energy rates involved. But physics more or less decrees that it can’t regenerate more power than it will take to regain the additional lost altitude. (I say only “more or less” because of things like gravity assist manoeuvres, which are fascinating but not applicable to craft like this.)
I was rather sloppy in the way I brought the regeneration up in my earlier comment. It was true, but not relevant because of this last paragraph. I didn’t think it through when I mentioned it at first.