Cool, here is a kind of balloon that combines hot air and helium. https://en.wikipedia.org/wiki/Rozi%C3%A8re_balloon https://en.wikipedia.org/wiki/Rozi%C3%A8re

Cool, here is a kind of balloon that combines hot air and helium. https://en.wikipedia.org/wiki/Rozi%C3%A8re_balloon https://en.wikipedia.org/wiki/Rozi%C3%A8re_balloon