Students, staff, and passersby may have noticed a black sausage-shaped object floating in mid-air outside CVTC’s Business Education Center in Eau Claire on a recent brisk fall day.
The attention-getter was a solar balloon being flown by Instructor Joe Flackey’s college physics class to demonstrate the potential use of energy obtained from the sun. It was the first use of the 50-foot-long balloon in the class, which resembled a black garbage bag.
“The black bag absorbs the sun’s rays and heats the air inside,” Joe explains. “As the inside air heats up, it expands and therefore becomes less dense. Since the air inside the bag is less dense than the cool outside air, it floats.”
Students conducting the exercise, who are enrolled in the two-year Air Conditioning, Heating, and Refrigeration Technology (ACHR) program, got a firsthand look at the use of radiant heat plus a demonstration of thermal expansion, density, and buoyancy.
The concept has applications in alternative energy, such solar heating panel use in warming outdoor pools or in radiant floor heating systems.
While the class’ balloon came from a kit, the same experiment can be done using very thin garbage bags. Students had to unravel it, run with it to fill it with air . . . and make sure it didn’t float too far.
“The balloon is actually large enough to show up on FAA radars,” Joe says. “So caution has to be taken to make sure it doesn’t get away.”
Physics Instructor Joe Flackey, at left in photo, and his students took advantage of a sunny day to fly a balloon energized by the sun.