Related to the sky lanterns of China and the aerostats of Leonidion, my hot air
balloons are frequently mistaken for UFO's. The term 'fire balloon' is also apt.
From a distance, mine appear as muted orange balls with a bright, throbbing
underbelly (photo below). The fire source is a tight packet of many birthday candles.
It's been nearly 40 years since I was suckered into believing I saw a UFO by some boys flying a dry cleaner bag. I learned to fly those too. Then I discovered I could make really big UFO's out of tissue paper.
My balloons are globe-shaped to maximize lift. The shape is determined by the shape of the individual panels (gores) which comprise the balloon. Having done more than enough computations of gore shape to last me a lifetime, I finally wrote a program to do the calculations for me. It's compiled into DOS. You are welcome to my balloon design program.
Photos
Plans