Originally Posted by [URL="http://www.pprune.org/members/270458-scuffers"
Scuffers[/URL]]Look, all well and good, but unless you plan on changing the laws of physics, simply not going to happen.
big as the A380 wing topside is, it's never going to be big enough for anything like a megawatt of power from solar.
Now, at best, solar is ~1,000W/M2, so if you had a mythical 100% efficient solar cell array the size of the A380 wings (some 845 M2) then assuming your A380 is directly beneath the sun, on the equator, you only have some 0.85Mw to start with, and as soon as said plane (it may well be slightly better at 40,000 ft, but not by a massive factor).
So where are you going to get "several megawatts of power" from?
this is not about a technology needing development so much as the physics simply don't stack up.
then consider that the Trent 900 is rated at some 80,000Lbf, which roughly equates to ~95Mw (40,000ft @ Mach 0.85) and the A380 has 4 of them.
Ok, thanks for the numbers. (I'm sorry I didn't look them up myself)
I wasn't thinking about getting an A380 to fly on solar. That's obviously impossible. What I'm imagining is more like a giant flying wing that carries much less, has the same wing span as the A380 but a much deeper wing, e.g. 80m wide, 40m long, carrying maybe 20 metric tons of stuff (maybe less - I'm just guessing things). That gives 3200 m2, yielding 3.2 MW.
This kind of plane would be much slower than a conventional plane, with extremely low wing loading.
What I don't know is, will passengers accept travel times in excess of 24 hours? In conventional planes, space for seats is expensive. In that hypothetical plane, space will not be a problem, weight will be. (And of course, flying through the night... ;-))
Crew block time will be a problem, I'm not quite sure how to overcome that. Fully automatic will be out, since I imagine the plane will need minders, unless you want it to look like a subway car in a poor city after a while. The cost structure will change for sure.
However, the main question remains - can a plane like that be made to fly? I really don't know if that is feasible. Probably not alone.