June 14, 2011
By Alyssa J. Miller
On a calm evening at AOPA headquarters at Frederick Municipal Airport in central Maryland, Aviation Explorers Post 320 learn the basics of assembling, testing, lifting off.
With 9 million Btu per hour spewing from this double-can burner during a test, Aviation Explorer Albert Coyne gets a sense of the intensity that heats air inside a hot air balloon for flight.
Sixteen Kevlar cables and four aircraft-certified carabiners connect the envelope and 275-pound basket, supporting a load up to 1,800 pounds.
Putting their weight into it, these Aviation Explorers learn that the envelope of a hot air balloon is heavier than expected. Including the envelope and bag, they're lifting 260 pounds.
A 5-hp fan with a 24-inch propeller inflates the 90,000-cubic-foot envelop two-thirds of the way with ambient air. Just like an aircraft, this fan doesn't perform as well on hot days.
While the 60-foot-tall, 59-foot-wide envelope inflates, Ben Eve holds the crown line to ensure that the envelope is controlled and stabilized during inflation.
With a tap of the burner, three students can lift the hot air balloon and both of its occupants with a light touch—a nice break after lugging the 275-pound basket and 260-pound envelope container.
What goes up must come down. Hot air balloons inflate and deflate similarly; with the envelope partially inflated, it moves diagonally from the horizontal to vertical positions (and vice versa).
Ben Eve helps fold the fabric onto itself, assisting with releasing the 90,000 cubic feet of air through the deflation port at the top of the envelope.
Air is quickly pressed from the envelope, taking about five minutes (and a few muscles) to deflate and secure it with straps.
Bunsen burners might bore some high school students, but when 18 million Btu per hour is rushing from what looks like two giant Bunsen burners, that’ll capture any teen’s attention—that along with the sound and radiant heat from the 10-foot-tall plume of fire it produces.
Three members of the Aviation Explorers Post 320 recently learned how to prepare a hot air balloon for flight. AOPA hosts the Aviation Explorers at its headquarters in central Maryland every other week to help the teens further their interest in aviation. In some cases, they can even take flight. The association supports the program, reinforcing its goal to help boost the pilot population and interest youth in aviation.
While the Aviation Explorers learn about different types of aviation during these events, they focused on hot air balloons for this hands-on lesson, helping assemble, inflate, deflate, and pack a 1996 Aerostar RX-8 hot air balloon, which has a 90,000-cubic-foot envelope. It didn’t hurt that they got to test a couple of giant burners during assembly either.
AOPA Director of eMedia and Online Managing Editor Alyssa J. Miller has worked at AOPA since 2004 and is an active flight instructor.
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