Hey, Mr. Kiran,
Thanks for highlighting this before Diwali. Enthusiasts will surely give attention in this.
Do anyone have heard sun powered balloon ?
Sky lantern is called FANUSH in Bengali and there is a house named PHANUSH_BARHI (means sky-lantern house). You perhaps seen that some colorfull sky lantern in different shapes like Kettle, Jokar, TajMahal etc. etc. have been flown in front of Victoria and in Viswakarma Puja at Indian Race Maidan of Kolkata. Those are made by Fanushbari.
This is not very long past and not even a decade. In that house I heard that some mathematician calculate (from ISI) and all family members prepare the Sky Lantern.
I have no news since joining this forum. It's near ChatuBABU-LatuBABU's House as per NEWS Paper. And the favorite Australian Tissue paper (Colored) that can withstand High Temperature, can not found now except White colored one.
Surely in this dewali, some Fanush (Sky-Lantern) I can show you. I prefer to glue all sheets (symmetrical of course) half folded as shown in the pic. (right top side.). A 15 minute in word processor build in drawing gives this, no graphic software.
As shown in the picture, you can make 2-6 or higher stage and hence longer sky lantern.
Moreover, using more radius by more sheets, you can make larger dia Sky Lantern.
But always make bottom round using bamboo stick (for light weight, and fire holder with Iron or Aluminum wire and preferably no SAG, sothat the baloon cannot catch fire.
Good Luck.