Flight 92: Released !'rom Alamogordo, New Mexioo, 0911 MST, August ;51, 1948
Recovered at Ft. Stockton, Texas
On this flight an automatic ballast valve (with ballast meter) was used
to support a 20-toot, .001" polyethylene balloon. The automatic ballast valve
operated properly for about six hours, and 3000 grams of ballast was ex-
hausted soon after sunset. In this case (Figure 41) the floating level of the
10
40
I
10 ..
ll
~I
~·
10
10
0
0100
r
I
1100
CILIJIIID eta.& I I ~ ........ ,...DID --' I ....
-- "'T r-. 1'-.I
·-·-·-........·-- ~
I I I I I .
FLIGHT 92
Rele...S at AJanllltDidD.NM
Allg. 31,1948- 0911 MSI
AeCCMNdcf Ft. 91ac111Dn,k
1100 - nao - 1100 1100 0100
T--MSI
GM20' Saloon with AIDnallc BciiCIIt Yalvt
Figure 41
balloon was not seriously affected by sunset as wa~ the case in Flight 90,
since the balloon had already descended to the activation level of the auto-
matic ballast valve. This descent followed about three hours of relatively
stable flight during which time no ballast v~s released. The 50oo-foot de-
scent represents the delay in operation caused by the activation of' the aneroid
capsule by a minimum-pressure ~itch, added to the lag of the aneroid itself.
Following the initial activation at about 38,500 feet, small oscillations were
introduced into the flight pattern by the action of the automatic ballast valve.
Flight 92 provides a good example of the control of a balloon's altitude
by the use of a pressure-set automatic ballast ~lve. In such a flight there
is no tendency to rise to higher and higher levels. The adulteration of the
lifting gas with ~ir reduces the buoyancy of the balloon, and through the
ball~.st-valve control, the load is diminished to the same extent so that
equilibrium is maintained at the activat~on pressure of the automatic be.llast
valve's aneroid. In this flight the altitude constancy achieved was the best
of all flights made to date. For seven hours and 35 minutes this balloon was
held within 1000 feet at 38,000 feet MSL. (At this altitude 1000 feet corresponds
to a pressure difference of 10 millibars.)
-50-