roswell

will cause the balloon to descend. Third, as a consequence
of the previous limi te.tion, the maximum floating period
of a balloon with thiw control system is 24 hours, achieved
when launching is at sunset.
~ben any or all of the above objections prohibit the
use of this simple control system, more complex ballast
dropping devices may be used. Figure 9 shows in schematic
form the servo or demand type control which has been used
to maintain balloons at a constant pressure level, with
high ballast efficiency and without harmful sunset effects.
Figure 10 is the ballast reservoir assembly which is used
with this type control. A more detailed discussion of
this servo-control is given in Techncial Report Number 2
of the Balloon Project, New York University.
c. Flight· Termination Gear
When a balloon loses buoyancy by the loss of lifting gas,
it sinks slowly to earth. To prevent the balloon from
remaining in airplane traffic lanes for a long period
of time, a flight termination device is added to the
equipment train. This device, shown in Figure 11, con-
sists of a pressure-actuated switch and rigging to tear
a large hole in the balloon when it descends to some
predetermined height. A pressure pen is held above
its commutator by a short shelf (see Figure 12). After
passing an altitude corresponding to the end of the shelf,
the pen falls onto the commutator. Upon subsequent
descent to 20,000 feet, it closes an electrical circuit.
When this circuit is closed, a squib is detonated in an
aluminum "cannon" (see Figures·l3 and 14) driving a pellet
through the main load line. As the line is severed,
the weight of the load is suddenly taken by a rip line
which extends nearly taut {about 2 feet slack) up the
side of the balloon to a point about 10 feet below the
balloon crown. At this point, two small holes about
18" apart have been made, and the rip line is passed from
the outside into the balloon through the top hole, then
down the inside and out the bottom hole. Both holes are
securely taped with t:~cetate fiber tape. About 6 inches
of slack line is left inside the balloon. ~ben the main
line is cut, a large hole is made in the fabric by this
rip line as it pulls out of the balloon. After the in-
struments have fallen about 10 feet and the rip is made,
they are caught up by a snub line and the load is again
taken to the load ring. The ruptured balloon then acts
as a parachute for the load, descer.ding at about 1000
to 1500 feet per reinute.
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