By now, unless you have been spending your time in an abandoned mine or something, you have heard about the saga of the “Balloon Boy” in Colorado. A spate of breathless news stories (like this one from CNN, via YouTube) reported that a six-year-old boy, Falcon Henne, had gotten into a balloon (which was sometimes referred to as an “Experimental Aircraft”) that was moored in his back yard, had managed to release it from its tethers, and was flying across Colorado.
The early reports described the craft as a “hot air balloon”. One of the reports showed a picture of the craft (in the backyard, presumably) with a person standing next to it. From that picture, it was obvious that the “hot air balloon” story was, well, hot air. The smallest hot air balloons capable of carrying a person (without a gondola or any other equipment) have an envelope containing more than 20,000 cubic feet of hot air; from CNN’s size estimates, the Balloon Boy’s contained less than 1,600 cubic feet, not nearly big enough to lift even a child. For comparison, a typical hot-air balloon used to give rides for 3-4 people at festivals, fairs, etc., has an envelope volume of about 100,000 cubic feet.
Later, the report was updated to say that the balloon was actually filled with helium. This would, of course, allow the use of a much smaller envelope, because the difference in density between helium and air (mostly nitrogen and oxygen) is substantially larger than that between hot air and cold air. The “GeekDad” blog at Wired has a post on this, in which he calculates that an envelope holding 1,571 cubic feet of helium could provide enough lift to carry a 50-pound child. However, as he points out, the aircraft is a balloon, not a dirigible (which has a rigid structure), and there is no evidence in the photos that the shape of the envelope was deformed at all by any weight it was carrying.
Now it is suggested that the whole thing was a hoax, created by the Henne family in an attempt to get a gig on a “reality TV” show. It’s also another disappointing demonstration of the gullibility and scientific ignorance of many members of the media.
The whole phenomenon of so-called reality TV seems to me, on one level, to be pretty weird. When I’ve asked a few people why they liked these programs, the answer was something along the lines of, “Well, I’m interested in people.” In some cases, I am reasonably sure that the person in question would only sit at an actual sidewalk cafe (say, Les Deux Magots in Paris) and watch actual people — you know, what we used to call “reality” — if “persuaded” at gunpoint. Evidently watching a bunch of amateur actors being paid to be followed around by TV cameras supplies something that reality lacks.