Flight 17: Released from Alamogordo, New Mexico, 1647 MST, September 9, 1947
Recovered at Croft, Kansas
On this flight the first balloon made of .004" polyethylene was launched. The altitude controls were a fixed-flow needle valve orifice set to leak at 100 grams per hour and an automatic ballast valve activated by a minimum-pressure switch.
This flight reached floating level shortly before sunset, and the balloon took on superheat which was lost when the sun went down. This cooling necessitated the rapid discharge of ballast to maintain buoyancy. The operation of the automatic ballast valve at this time was satisfactory and restored the balloon to a floating level within one hour. Following restoration a satisfactory floating performance was indicated for as long as radio contact was maintained (Figure 11). The need for a balloon-borne
[figure]
Figure 11: Height-time curve, Flight 17
barograph was demonstrated by this flight which traveled more than 500 miles from the release point.
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