roswell

VIII. ANALYSIS
During and following the flight it is customary to analyze the
behavior of the balloon. Two curves are usually drawn when
data is available for their preparation. The first of these
is a time-height curve which gives the altitude of the balloon
at all times with respect to sea level. On this curve also
it is customary to plot tne temperature data and ballast flow
data when such has been recorded. In some cases it has been
found useful to plot a profile of the terrain over which the
balloon is passing. The second diagram usually prepared is
the trajectory of the balloon, and again it may be prepared
with respect to the terrain over which the balloon was passing.
That is to say, it is plotted on an aircraft map of the area,
with positions and heights plotted every ten minutes. Fig-
ures 38 and 39 show sample p.lots.
IX. GENERAL MILLS 7-, 30-, AND 70-FOOT BALLOONS
The altitudes reached and loads which may be carried by the
General Mills balloons other than the 20-foot cell are shown
in Table 4, Appendix II. Graph 3, Appendix II may be used
for interpolation of the tabulated values to give the re-
lationship between floating altitude and gross load, and Graph 4
shows the altitude sensitivity at various heights. It has
been assumed that helium is the lifting gas. Graph 1, Ap-
pendix II is useable for all of these balloons to determine
the amount of free lift which .is needed to give a desired rate
of .rise.
To launch a 7-foot balloon, it is not necessary to utilize
the elaborate technique of the larger balloons. A can of sand
is made to weigh the same amount as the required gross lift
(equipment weight plus free lift), and attached to the load
ring. Inflation from a single tank may be made insX8 any
building with relatively large doors and when the balloon just
lifts the inflation weights it may be attached to the equip-
ment line, carried outdoors and released. In light winds the
equipment may be released with a hand-over-hand paying out of
the line. If there is too much wind for this method, the
equi~ent is laid out downwind and the balloon released so as
to pass over the pieces of gear and pick them up while rising.
A 7-foot balloon being inflated is seen in Figure 40. The
appendix which is shown is made of a flattened 2-foot length
of inflation tube, from a 20-foot balloon, without stiffeners.
Such a balloon has been sustained with a fixed ballast leak
-71-