roswell

the same time that ballast is normally required in flight. T.his
system simulates the effect of rising and falling in the atmosphere
and indicates the effectiveness of the controls which have been app~d.
In order to simulate flight, it is necessary that three conditions
be mainta·ined within the system. The first is that a leak of air
into the bell jar is pennitted at a rate of pressure increase which
has been observed during balloon descent. A large lag chamber is
connected into the bell jar to supply the second condition which
is a delay similar to that inherent in the control action on an actual
balloon flight. It is •necessary to properly adjust the vo!ume of
such a lag chamber to obtain the desired magnitude of control action.
A third requirement is that the response of the vacuum pump must
correspond to that response which has been observed when a balloon
system drops ballast. In order to measure this, the control me-
chanism has been allowed not only to switch the vacuum pump on and
off but also to actuate the standard ballast-flow equipment. This
system may be adjusted so that the amount of pressure change which
a single period of pumping produces accurately represents the amount
of ballast thrown off during flight.
T.he barogram shown in Figure 18 is e.n example of such a test. On
this test the re.te-of-ascent ballast switch v.ras added to the displace-
•Hours •
Fhaht Samahtude Record Of Pressure
A- Oasplacement Swatch
OperatanQ.
B- Oaspl. a Rate Of Ascent-
Swatches OperahnQ.
Figure 18. Sample barograph record.
ment switch after the latter had operated for a period of six hours.
The combination of the two is seen to have effected a reduction in
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