Why weren't hot air balloons invented earlier?

Building a hot air balloon big enough to hold a person is very difficult and wildly dangerous, particularly when you don't have access to flame-resistant fabrics. At the same time, there really wasn't a lot of practical application to building such a balloon. read more

On June 24, 1784, in Baltimore, 13-year-old Edward Warren became the first person in America to go up in a hot-air balloon. In this picture book, Van Leeuwen lets the boy tell his own story, which focuses more on his passion for flight than on the significance of this moment in aviation history. read more

hot air is less dense than cold air. that is, hot air takes up more space, or, in a given volume, there is less air in it. the denser, cold air tends to push the warm, less dense air up, as for the same volume, there is less air, so it weighs less than if it were cold air. read more