(This is my first post since the new forum software.)
I watched Tesla battery day on video. Even the battery critic gave the new battery design an A+
I wonder if the brand new Tesla 4680 batteries change the ballgame. Reportedly, they started an assembly line that continuously moves and can manufacture these 20 gigawatt hours of batteries per year in one-seventh the size of factory space. Just ONE serial assembly line, nothing parallell to it. Looked like soda bottle manufacturing in a high-speed assembly line! They could easily scale up to terawatts-hours per year in a decade with what I've seen.
They are planning lithium battery prices planned to fall to $62 per kilowatt-hour by 2030, and about $30 per kilowatts-hours by ~2040. Even with the extra cost of battery packaging and integration, I would not be surprised that it will become sufficiently affordable enough, that at least one or two skydiving dropzones converts an old Caravan to battery during an ordinary engine overhaul. Using, say, a FAA-approved Magnix-like overhaul and go through the right regulatory hoops, and it becomes cheaper than a turbine overhaul in about 10 years. No new airframe needed!
The copper-ends of a 4680 apparently simplifies cooling, since 70% of the heat occurs at the end, allowing a simpler heatsink cooling plate approach (airframe can act as heatsink). They were able to fit 130-kWh of batteries in the same space & weight as 74 kWh, despite only being 5/6ths smaller, because of the way battery cooling was massively simplified, and that the batteries themselves became structural elements of the new Tesla battery pack.
The batteries recharge faster. According to my horsepower math (wattage, weight, etc) and the charging speed of the new Tesla 4680 batteries -- there is apparently enough charge speed for 15-minute full power 1 extra skydiving flight after a 15-minute fast recharge (megawatts-scale recharging). So you could just tolerate and pad the schedule for slower boardings, in order to reap the cost savings. Even aviation fuel powered often loiter that long waiting for stragglers anyway and tandems to get ready on a semi-slow day anyway. You'd cycle less often, but you'd cycle much more cheaply, with a fraction of the maintenance cost and fuel cost. And this is just a shallow cycling (30% to 80% recharge), which is now more than needed for a 13500 feet skydive, given a sufficiently sized battery (at projected circa-2030 capacity).
It might not be till approximately 2030-2040 before this happens, and regulatory makes it easier to do electric-conversions, but it's now within realm of possibility.
The electric Caravans jump planes of the 2030s may carry 2 or 3 or 4 less skydivers, but at much cheaper than petroleum and much cheaper maintenance -- the DZO economics of a profitable $10-to-$15 funjumper jump ticket is quite tempting even if the Caravan capacity is slightly less (10 passengers or 5 tandems). Get an extra jump plane instead to make up the capacity shortfall; the savings actually more than pays the salaries of extra pilots.
The battery of the prototype electric caravans outputs more horsepower, than the turbine motor it replaced; so that compensates quite a bit for reduced capacity -- it can then thus safely haul more weight (its battery) off the runway, reducing the scale of loss of passengers to just a few percent of the plane's passenger capacity.
And still be able to zoom up to jump altitude like a turbine at full throttle while still only eating under 50% battery charge (which can now be recharged in 12 to 15 minutes) -- whee! Shallow cycling can be done 10,000 times, since it's the below-30% and above-80% charges that is the most damaging to a lithium battery (1000 full-charges instead of 10,000 half-charges or maybe 50,000 quarter-charges -- it scales somewhat geometrically to an extent, depending on the specific lithium chemistry). So replacements are rare if you size for shallow cycling, that's how gridscale lithium batteries are designed to last for a couple decades.
Who cares if you gobble 25%-to-50% of battery per skydive, if you can recharge for the next flight in just 12 to 15 minutes (to add back 25%-to-50% capacity) with electricity much cheaper than aviation fuel? More than enough cost savings and profit to tolerate the longer pauses between flights.
Mind you, the huge price drops of lithium batteries has been rather jawdropping.
I now view electric jump plane conversions economically price-realistic by ~2030-2035 since cost projections suggest potential increases DZO profits / reduces jump ticket prices sufficiently enough to have far quicker ROI than a turbine conversion.
Give it a decade. It'll happen to at least a few dropzones after year 2030.