The invention of relatively light burners fueled by bottled propane made it possible for the balloonist to re-heat the air inside the balloon for a longer flight.

Yost patented further refinements he made to the hot-air balloon, including nonporous synthetic fabrics, maneuvering vents, and deflation systems for landing.

[3] In October 1955, Yost developed and flew the first prototype of the modern hot-air balloon in a tethered flight.

Raven was founded in 1956 by Paul Edward Yost, J. R. Smith, Joseph Kaliszewski, and Dwayne Thon, while working in the General Mills scientific balloon program.

Headquartered in Sioux Falls, SD; Raven was contracted by the US Navy's Office of Naval Research (ONR) to create a reusable, lightweight balloon that would carry a pilot to 10,000 feet and fly for three hours.

On October 22, 1960, Yost lifted off from Bruning, Nebraska, on the first-ever free flight of a modern hot-air balloon.

[4] In November 1960, Yost made a second flight with an improved balloon from the famed Stratobowl, near Rapid City, South Dakota.

Raven Industries sold their first civilian hot air balloon in November 1961, launching a new sport in the process.