Up, up and away!

Model Airplane News, Apr 2005 by Baier, Karen

AN RC HOT-AIR BALLOON TAKES FLIGHT

THE PLEASURE IS IN THE JOURNEY for Dave Milliard. After working as a machinist and parttime drafter at a steel mill in Butler, PA, Milliard-president of the Butler Area Radio Flying Society-fills a chunk of his retirement hours by blending his skills, tools and love of RC model airplanes to create one-of-a-kind flying machines.

"My big hobby is RC airplanes, but 1 like to draw them and build them more than fly them," he admits. His latest creation, though, is a 1Ascale hot-air balloon. After seeing one fly at a festival in New York state, he was intrigued. Since there's nothing he likes better than developing a concept's specifications and drafting them into a hand-crafted finished product, Milliard knew he _ would enjoy whatever came next.

By chance, he came to possess the rip-stop nylon material of the decommissioned "Silent Sea"-a full-size balloon that was 85 feet tall and 65 feet wide when fully inflated. He decided that he wanted his balloon to be 15 feet in diameter, and he used a photo of the original as a guide to its design. On the nylon, he measured equidistant horizontal segments from the bottom rim to the top along the perimeter. Arriving at a 22:1 ratio, he calculated the dimensions needed to create a balloon that would be 21 feet high and 15 feet wide, fully inflated. He drafted a pattern for the shaped vertical segments and cut 12 of them out of about 85 yards of fabric. The next step-sewing the pieces together-was time-consuming but not difficult. Hilliard used a regular sewing machine bolted to a worktable that he designed and built to support the nylon's weight, which increased as the balloon took shape. Turning his attention to the gondola (the basket that hangs beneath the balloon), Hilliard again used the pohoto as a guide to design a scale version. In his hands, twine and bamboo kabob skewers became basket-weaving materials.

Then it was time to concentrate on the mechanics of the project: heating the air. Working from the details of a full-size burner, Milliard drafted and machined the parts he needed. "The air and gas mixture has to be just right. It took me a whole day of drilling holes to produce an almost invisible blue flame." Fueled by propane from a 2-pound, "short, squatty cylinder," his burner can produce a jet of fire that's 8 inches wide and 3 feet high. He controls the flame with his radio with only two positions-burner off and burner on-just like the controls in the full-size apparatus. One tank provides about a 12-minute flight. "It roars just like the real thing," Hilliard says cheerfully. From a weed-whacker, he salvaged a gasoline engine I that powers the blower. Although the blower can fill the bag, cool air won't stand the balloon upright. Because he wanted to heat the air that enters the balloon in a different way, Hilliard devised a hand-held propane burner with a 3-foot-long wand and the same tip as the burner affixed to the basket.

At the flying field, Hilliard prepares his model by following the same steps as pilots of full-size balloons take. When the balloon is inflated, he switches to RC and ignites the burner to make it ascend. "It gets there in a hurry," he laughs. "If I didn't tether it, it would be in your view for about only 30 seconds." Instead of allowing the balloon to use all 150 feet of its tether, Hilliard prefers to maintain an altitude of about 10 to 20 feet so that spectators can see how it works. How often does Milliard's crowd-pleasing balloon lift off? "Whenever someone wants to watch," he says with a grin. Judging by our enthusiastic response, that must be quite often!