I always wanted to get one of those surplus weather balloons. The power of advertising, I guess. :-)
I bought one once and figured I’d get lift by filling it with hot lawn mower exhaust. At 10 or 11 years, I had no idea how to do any calculations, so it was empiricism all the way. It inflated, but flopped over and wouldn’t even stand up at all. What a huge disappointment that was.
Ha - they still carry ant farms and dunking birds. Either one of those would drive our cats right up the flue. *chuckle*
My mother bought one for us when we were kids. She thought it would be fun to launch a balloon 12’ in diameter. Problem was, no way to fill it with helium so it would go up. We used a bicycle pump and pumped all day only to discover compressed air doesn’t rise. Still, kept us out of trouble for a couple of hours. BTW, in reference to your tag line, my father was a career Army officer and in the late 50’s - early 60’s we were stationed at Poitiers, France.