roswell

The pen drops off the shelf at a safe distance below the ex-
pected pressure altitude and ballast then flows until the
preuure pen reaches the insulating section of the commutator.
In order to prevent the-overshoot mentioned as one undesirable
feature of the automatic ballast system, the high pressure
end of the insulator may correspond to the expected maximum
altitude of the balloon, any loss of lift due to impurities
or escape of lifting gas will cause the balloon to level off at
a ceiling within the ballast-dropping range. Continued ballast
dropping will result in the rise of the balloon. Thus, an over-
estimation of the ceiling is not as critical as in the case of
the previous system.
(3) Rate-of-Ascent Switch
Wit·h the displacement-switch control just described there re-
main the problems of ballast waste and balloon oscillation re-
sulting from discharge of ballast during rises of the balloon
after a descent has been checked. To eliminate this, a ballast-
control .witch acting on the rate of rise of the balloon is
put in series with the displacement ~itch to close the ballast
flow circuit only when the balloon is coming down or floating
below pressure altitude. When it is rising, no ballast flow is
permitted. This "rate-switch" is seen in Figure 12.
Wax
/Capillary
/ Tube
Volume
Chamber
Figure 12. Rate-of-ascent nitch.
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