SMT007 Magazine

SMT007-Feb2022

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8 SMT007 MAGAZINE I FEBRUARY 2022 Nolan's Notes by Nolan Johnson, I-CONNECT007 Feeling the Heat of Rising Input Costs About 10 or 12 years ago, one of the fam- ily activities I engaged in with my children was hot air ballooning. At one point, my son and I even had student pilot licenses for them. My daughter would have had a license as well, but she wasn't quite 14 at the time, which was a requirement to get a hot air balloon pilot license. Most of our time, though, was spent as volunteers on the ground crew. My kids were right at middle school age at a that time, so bal- looning was a grand opportunity to teach phys- ics, especially Newton's laws of dynamics. e typical recreational hot air balloon that you see at festivals and such, with a basket just large enough to hold two propane tanks and three or four people, has the capac- ity to hold about 90,000 cubic feet of air, plus or minus. Imagine that nylon enve- lope holding 90,000 basketballs. At first, that seems like quite a lot of space, all floppy and stretchy. Except those bal- loons are definitely not stretchy. Current designs for hot air balloons were, believe it or not, developed by the U.S. military in the mid-20th century as a potential "silent entry" military use vehicle. Ultimately, the propane burn- ers were too noisy and too bright for night use 1 . But the general structure they developed became the modern hot air balloon. e structure starts with a metal ring, milled out of billet alumi- num, that is about 18 inches in diam- eter. Attached to that ring are a series of fabric straps (like those in your car's seatbelt), which make up the vertical support for the balloon. In fact, the bas- ket will attach to the opposite end of all these vertical trusses. Horizontal straps of the same material will wrap around the balloon, defining the general shape

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