So is it possible that an airship could actually fly using a steam engine? For example a blimp like airship that could carry a dozen or so people, as well as coal for a fuel source, and obviously a steam engine onboard or would fall that be too heavy? Once airborn I was thinking it could use air currents to save on fuel. Curious about the possibilities, pros and cons of a steampowered air ship.
After a second thought, I think I will post my comment as an answer.
A steam engine requires: a high-pressure boiler, lots of water, and plenty of fuel (coal, usually). All of those things are heavy. The boiler usually is a massive bulk of stainless stell, you need several tons of water for a small-to-medium boiler, and a similar amount of coal. Normally, that's heavy enough to be impracticable. In real life, airships only developed after the internal combustion engine was developed (much lighter engines with much lighter fuel, and no water at all).
Even with some handwavium about the boiler's size and weight, the problem with steam engines is that the power output of the engines depends on the steam. You need a lot of steam or a extremely hot steam to produce a powerful output. A lot of steam needs a lot of water, while a very hot steam needs a lot of fuel and a extremely strong boiler (and so, bulky and heavy).
It's not actually that bad
What people forget is that the steam engine has also had significant improvements in the technology over the centuries. It's a lot lighter and more efficient than the early engines. It's also important to note that the low torque high speed rotation of a propeller is an entirely different beast from a railway engine.
Consider the Keen Steamliner, it's an oil burning steam powered car, on the outside it looks like an ordinary small sports car (I can't testify as to its handling). The biggest problem is the water cycle, if you don't have a good condenser then you're going to have a lot of water losses and that means carrying a lot of water, you must have a closed cycle engine. Luckily airships and condensers have one important factor in common: A large surface area.
Coal is harder to handle as a fuel than oil and the energy density is significantly worse, but you're not asking the impossible