AIRSHIPS AND HOT AIR BALLOONS
1. Object Sizes Airships and hot air balloons are frequently mis-reported as UAPs, probably because their appearance in the UKADR is still relatively rare in some parts of the country, and the fact that they are at low altitude. However, ballooning is a growing sport and an increase in false alarms from this source can be expected. Both UK-produced and imported balloons can be expected in UK airspace, including balloons of novel shapes (e.g. cylindrical). The situation is enhanced by the fact that balloons are often silent for long periods, and airship engines are relatively quiet. Table 1 shows a selection of typical parameters for airships. Balloon diameters are typically 22m with a height of 26m. The use of gas burners at night is a particular source of reports of ‘glowing spheres’, particularly in Southern England.
2. Report Incidence If a number of design proposals proceed, the incidence of both cargo and passenger airships can be expected to increase; however, their appearance will still be relatively rare to most observers, compared with other familiar air-objects such as aircraft and gliders.
3. Meteorological Balloons These are described at Working Paper No 14.
4. Tethered Balloons While tethered balloons are less likely to be mis-identified as a UAP, by stationary observers, an observer in a moving vehicle may catch a glimpse of a tethered balloon in the appropriate weather and lighting conditions and submit an event report. In the UK, tethered balloons of up to 20ft in diameter may fly up to 200ft AGL, without tether streamers (the presence of streamers would almost certainly have eliminated many false reports).
5. It should, however, be noted that the presence of a tethered balloon may, in fact, attract an atmospheric UAP which is seeking an attracting electrical potential, since a charged mass of air may be attracted to the balloon or it’s tether.
6. Tethered balloons may remain in one position for up to 10 days.
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