Hi. I have to do 4 hour long flight with breaks for battery change only (under 5 minutes). How many TB47 (smaller ones) I have to have to do it without stress? How many power supply? Flight time will be circa 15 min on one battery (stable shooting like time lapse on one height). Charging time is 80 minutes (let it be 90 min to be sure). Is my math ok if I would have six batteries and four chargers? Flight cycle is 15 min of flight, 90 min charging, 15 min of cooling, then flying again on the same battery. So total time of cycle is 2 hours. Please help Regards!