Just think of the extra weight!
The steam-powered locomotives of the 19th and early 20th centuries capitalized on the inefficient, yet powerful, nature of the steam engine. The combustion engine wasn’t popularized until Henry Ford made it the latest technology for personal transport. Even after automobiles had revolutionized industry, there were many who longed for the days when steam power was king.
Inventors had been making various steam powered contraptions for centuries (the first was in the 1700s), but it was only during the 1930s that the concept of a steam engine airplane came into its own. The Besler Brothers, inventors of various planes, designed the only steam powered airplane to have ever successfully taken flight. The Besler plane combined elements of both car and train models of the era.
In this British Pathé newsreel its called a wonder, but there are quite a few good reasons to not use steam power for airplanes, like weight. The steam engine, boilers, and condensers added about 400 pounds to the small biplane. But, the craft could commit to short landings because of its reversible engine which could propel the plane backwards in the blink of an eye. Have a look in the video below.