Three rates, and only the slowest one matters
Put the default numbers in — six packs, nine minutes of flying each, four minutes on the ground between flights, twenty minutes of cool-down, forty-five minutes on charge, two charger channels — and the page prints three rates that have nothing to do with each other. The flight line could turn round 4.62 flights an hour. The fleet could support 4.86. The charger can manage 2.67. The charger is the day.
The useful part is what that implies about spending. A seventh pack raises the fleet rate to 5.68 an hour and changes the session by nothing at all, because the charger was never waiting on packs. A third and fourth channel raises the charger to 5.33 and the day becomes flight-line limited instead. Same money, completely different outcome, and no way to tell which from the flight log alone.
The warm start is worth more than it looks
Six charged packs at the start of a session is six flights that owe nothing to the charger. At the default figures the page counts 11 flights in three hours; the steady-state charger rate of 2.67 an hour over three hours is 8. The extra three are entirely the packs that were charged the night before, which is why the page simulates the session rather than dividing the length by a rate.
It also means the fleet size matters most for short sessions and least for long ones. A two-hour outing is nearly all warm start. A full day is nearly all steady state, and the fleet is just a buffer feeding the charger.
What never waiting would take
The line calls for a fresh pack every 13 minutes. A pack is out of circulation for 74 — nine flying, twenty cooling, forty-five charging. Six packs is exactly the 5.69 that rounds up, so the fleet is sized right. The charger is not: 45 minutes a pack across a 13-minute demand needs 3.46 channels, so four. Two channels is less than half of that, and the page says so rather than issuing any verdict about it.
Cool-down is the quiet part of the 74 minutes. It is 27 percent of the time a pack spends unavailable and it produces nothing. If that figure came from the pack maker then it is what it is. If it came from habit, a thermometer settles it in one afternoon.
What the page does not know
It assumes packs are interchangeable, that a charger channel runs at full rate whatever else is plugged in, and that you launch the moment a pack and a machine are both free. Real sessions lose time to weather, to a card that will not mount, to people wanting to talk to you, and to the last flight of the day that nobody hurries. Cheap chargers also share a power budget across channels and slow down when several run at once, which this does not model — if yours does that, put the slowed figure in the charge time field rather than the datasheet one.
Charging on a generator or an inverter at the field brings its own limit that is not one of the three above. The energy block at the bottom prints the continuous watts the whole bank asks for, which is usually the number that decides how many channels you can really run.
Questions people ask
How many LiPo packs do I need for a flying session?
Enough that the fleet rate is not the slowest of the three. A pack is unavailable for its flight plus its cool-down plus its charge, and the flight line asks for one every flight-plus-turnaround, so the count is the first divided by the second, rounded up. At the default figures that is 74 minutes divided by 13, which is six. Buying past that changes nothing unless the charger can keep up, which at two channels it cannot.
Why does the page count more flights than the rate suggests?
Because you start with every pack charged. Those first sorties do not wait for the charger at all, so the session runs at the flight-line rate until the charged packs are gone and only then settles to the slowest rate. The shorter the session, the more of it is that warm start — which is also why fleet size matters most for a two-hour outing and least for a full day.
Should I buy more packs or another charger?
Read the three rates. Whichever is lowest is the only one worth money, and the page names it. At the defaults the charger runs at 2.67 flights an hour against a fleet capable of 4.86, so a seventh pack does nothing and a third channel does a great deal. Adding to the wrong one is the most common way to spend money on a flying day and get the same number of flights.
What cool-down time should I enter?
Whatever the maker of that specific pack states, or your own standing practice if you have one. This page does not have a figure to offer and will not invent one — it is an input, and 20 minutes is sitting in the field as a placeholder to replace. It matters more than people expect: at the defaults it is 27 percent of the time a pack spends out of circulation.
Does this account for charging at the field on a generator?
Only in the sense that it prints the continuous wattage the whole bank draws with every channel running, which at the defaults is 261 W. Whether your generator or inverter holds that is a question about your equipment. If the supply cannot feed all the channels, run fewer channels in the form — that is exactly the situation the charger rate is there to expose.