Peter wrote:
Swappable battery packs are a difficult thing to implement. Not technically but “politically in the field”.They would be extremely expensive – 4 digits at least. So security is a big problem. You are talking about stuff which is very stealable.
Then there is the issue of trading your new one in for a shagged out old one. Nobody would want to do that. It would be like trading a new $10k KI256 for a 1982 one from an extended warranty pool (which is exactly what happens; most of the extended warranty pool is shagged out old crap So the mfg would would have to set up a system where each pack would have a cycle counter on it, and if you traded yours with a count of say 1000 for one with a count of say 3000, the “swap shop” would pay you some compensation equivalent to the 2000 cycles difference. And it would be substantial – 3 or 4 figures. So whoever is running this charging station (which cost them hundreds of k to get wired up) is gonna be really p1ssed off when a load of brand new electric plane owners turn up!
I’m not talking about “trading packs.” I was discussing with the Pipistrel representative the possibility of having two packs for the aircraft, charge one of them while the aircraft was flying and then swapping packs between flight. He recommended strongly against it because of the time and effort it would take to swap packs.
Electric commercial transport may work for small twins on short routes – eg interisland Orkney. Wind turbines to charge the swappable batteries. With present technology.
the possibility of having two packs for the aircraft,
Then you are carrying the weight of a spare pack, no?
I think he means the spare pack stays on the ground being charged – each aircraft ‘owns’ two packs which only it uses.
Useless for A-B but might just work for endless circuit training.
For circuits, the issue I pointed out with mixing up packs isn’t there anyway, because every plane (or more like every school) can have their own pile of packs.
A-B is the problem, indeed.
Peter wrote:
A-B is the problem, indeed.
You can still charge the batteries as usual. A to B is no problem. It’s only a matter of time used and the number of stops. If speed is of the essence, getting from A to B as fast as possible, then this is another matter entirely.
Take the Alpha Electro. Considering Avinor is getting chargers on all their airports, one could fly all along the coast of Norway effortlessly. According to the specs (I think), it will have an endurance of 75 NM at 80 kts. From ENVA to ENBO is about 260 NM. This could be flown in one leg with an ordinary Alphatrainer using 2-2.5 hours. With an Alpha Electro at 80 kts, it would take 2.75-3 hours, but 3 rechargings will be needed at 45 min. Let’s round that to 1 hour at each charge, and the trip will take around 6 h. By car it takes 10-12 hours, so it’s still faster than car. With an electric car? double that 
(not a doubling, but considerably longer).
Anyway, the point is, it can readily be done. There are no show stoppers. And if all I’m going to do up there is to fly around the mountains of Lofoten, taking pictures, does it really matter if it takes 6 hours to fly up there? I mean, I’m flying for the fun of it in any case.
A:B may be a problem for the likes of ourselves. If you were running some sort of commercial, scheduled service it would be OK. In any case, fast charging seems to be getting ever faster.
As Silvaire said, the X57 is experimental (it’s in the name) but I think it still illustrates how a small, short range electric/hybrid aircraft ought to be designed differently. Apparently having the propellers at the ends of the wings reduces wingtip vortices. I can see that it wouldn’t be much fun to fly asymmetrically, but then if you have 12 more propellers to hand you ought presumably to be able to cope in other ways should you need to. Another potential is to use the motors to control yaw/roll to avoid using control surfaces. I have no idea how much this is meant to increase efficiency… but apparently it should.
Graham wrote:
I think he means the spare pack stays on the ground being charged – each aircraft ‘owns’ two packs which only it uses.
Exactly!
LeSving wrote:
I just remembered having read it somewhere. Can’t speak of the reliability, but it say so here. kind of…
That does imply that you can change a pack in less than 10 (5+5) minutes The aircraft has two packs. And the document was dated 2017, while I was talking to Pipistrel in 2019. I guess the only way to know for certain is to ask again.
