topband@contesting.com
Edmund balloons; questions
I've been using the 3 ft Edmund balloons, with
moderate success - when the wind lets up. These
are called weather balloons, and are said to be
designed to burst when they reach a certain altitude.
I filled one to 4 ft, and it behaved much better in the
wind. (The lift increases by a factor of 2.37, while
the wind load area increases by a factor of only
1.78.)
1. What is the designed bursting altitude?
2. What is the designed bursting size?
3. What is the safe inflating size?
4. I also have an Edmund 8 ft balloon which I haven't
tried yet. I'll try inflating it to only 5 or 6 ft at first.
(Compared to 3 ft, at 6 ft the lift increases by a factor
of 8, while the wind load area increases by a factor
of only 4.)
Has anyone used these 8 ft balloons?
5. The simple wind load area calculations ignore the
balloon shape. Can someone calculate the wind load
correctly?
6. After 2 days aloft, a 3 ft balloon shrunk down to 2
ft. This is a loss of 70 % of the helium in 2 days. Is
that normal?
7. Are there better balloons available?
73,
Mark, K5AM, DM62ni, k5am@lascruces.com
Mark Mandelkern
Las Cruces, New Mexico, USA
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