The military has flying tankers to “recharge” fighters, so why not flying batteries to recharge flying electric taxis?
IIRC, you lose approximately 20% of the power applied to charge a battery as heat. Then you lose another 20% when you use that power to charge the air taxi battery... Your power density is already low, and you’re going to throw away a large portion of it as waste heat. Also, the faster you charge that battery, the more waste heat you get, and the shorter the battery life. NRTZ was the code we used in the USAF for Not Economical To Repair... This idea is NRTZ!
Maybe if we ever manage to make & perfect superconductor capacitors... But chemical storage batteries just aren’t up to the demand.
“why not flying batteries to recharge flying electric taxis?”
That’s a novel thought, but it doesn’t pass the “quick smell test.” It takes ten to fifty times longer to recharge a battery as it does to recharge a liquid fuel tank. The shorter recharging times require huge amount of electricity delivery.
Where would you get such large amounts of electricity in a “battery tanker”? Either it would carry huge amounts of very heavy batteries or it would have an on-board charger. The “battery tanker” itself would probably be powered by JP4, so you would be burning up fossil fuels in the air to deliver a recharge to an in-flight electric airplane. Or the “battery tanker” could have an on-board engine/generator set producing power in the plane (perhaps tapping off one of the main engines on the wing). But what would be the energy source for that engine/generator? JP4, of course.
Sorry, it doesn’t pass the smell test.