330-PSA-26-61 (USN 1052544):  U.S. Navy’s Hot Air Balloon Completes Successful Test.  U.S. Navy’s hot air balloon which uses the hot air principle for buoyancy completed a successful test flight in November 1960 over the Stratobowl balloon launching site, Rapid City, South Dakota, the 9,000 foot, 2-hour flight was made by Mr. P. Edward Yost, director and test pilot of the project.  Mr. Yost made the flight while suspended in a swing seat with a backrest and both his feed resting on trapeze bar.  Research on the hot air balloon system is being conducted Raven, under contract to the Office of Naval Research.  Principle advantages of the hot air balloon are economy of operation, greater load capacity, and greater flexibility in ascending and descending without requiring the use of ballast.  A large burner is used to accomplish initial inflation on the ground.  A portable burner fed from propane gas tanks is carried inside the mouth of the balloon.  Varying the burner flame controls the ascent and descent of the balloon.  A high flame sends the balloon, or brings it down.  The lower portion of the balloon is protected with glass cloth.  Another advantage of the hot air system is the ease in preparing for launch.  The entire process required 35 minutes in the test flight.  The balloon presently being used in the experimental manner flights is made of nylon with a nylon plastic laminate.  The balloon is about 40 feet in diameter, measures 27,000 cubic feet and can carry a maximum load of 600 pounds to 15,000 feet.  It is reusable, and more flights will be made with the same balloon. Photograph released January 26, 1961.  (9/15/15).
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