roswell

Example: It a 20-foot diameter balloon~ full were tested at
10
sea level and found to have a leakage rate of 50 gmfiu-. the
leakage rate of a full 2D-foot balloon at sea level would be:
Lt • eo;-{1o)f • 34ol
The leakage of a full 70-foot diameter balloon at sea level in
this case would be:
lf • 50 ~ [tof:g}a]f =7820 GII/HR
Values for leakage at several different altitudes for 20-foot
and 7D-foot diameter ballcons, assuming a leakage of 50 ~r.
for a 20-foot balloon~ full at sea level are:
10
.1 titude (MSL) 0 40,000 ft. 100.000 ft.
2o-ft. diam. 340 r. 83.2 r.
70-ft. diam. 7820 r. 1912 r.
Another consideration is that relationship expressed by the
kinetic theory of gases regarding gases at low pressures. The
kinetic theory states that there is a molecular type of flow
across a thin diaphragm through openings whose dimensions are
of the order of the length of the mean free path of the mole-
cules involved. Mass flow of the gas is then:
where:
L = ~p·A~
120
Jl p : 1s the pressure difference across the film
A = area of the opening
dCJ = density of the gas in question
This. relationship, however, becomes valid ot~ly at extremely
low pressures, and when considering balloon systems at no:nr.al
floating levels the more common fluid-flow relationship will
control the rate of loss of lift through openings in the film.
It would be of little use then to investigate further the leak-
age of gas through openings by means of the relationships in-
volved in the kinetic theory.
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