Flight 75: Released from Alamogordo, New ~~xico, 1010 MST, July 20, 1948
Recovered at Hollister, California
In order to reach higher altitudes than was possible when 20-foot plastic
balloons were used, a 70-foot, .001" polyethylene cell was flown an Flight
75. To determine the duration of buoyancy of this type of balloon no con-
trols were used. Despite this, the balloon remained aloft for more than 60
hours and successfully withstood the loss of superheat occasioned by at
least two sunsets. From the height-t~e curve of this flight (Figure 29)
the very marked effect of superheat is apparent.
100
,.......__
I YSUNSI:T(IIt)
- \ ~ SUNSETC211d)
\ ,,--- \- I (Srd) SUNSET~
" ~' 1- ........._____
\
\\ .I
.. I ,
'"- "' \, "'=- .,/
; .. ~ .... ,. ....
~
• FLatT 75-BAROIIW"H Rf:GORD·
... 7d 8.M. BALLOON- NO GONTitOI.S
.. Silo•.. Naltlrol Stollllltr Of
0 Baloo• At Hltll AlfltHio
1 RlleiiHd At A~aMtordo,N.M.-- 20.1.48
Rooonrod At Holhltor, Col-Aq. 22,1M8
Elt-.ted fl!lht Durofloe- •o Houn
~ "
I
tz
I I I I I II L Ll UJII I I I I I I I II I II I I I
0 I I I I I I I I I I I I I I'
1100 2200 I 0400 1000 1800
-------J~Y20G-----~•~-·~-------JUU21
TIME-MST
2200 I 0400 1000 1600
•· • JULY 22---
Figure 29
The record of the barograph was not complete since the clock stopped each
night (clearly recording the lowest elevation reached, however) and ran
down completely after 56 hours.
Since the small external appendix with cardboard stiffeners was not
suitable for the large balloon, a new design with aluminum formed stiffeners
(Figure ~0) was used. This type of appendix closer worked well on later
flights, and it is likely that the long duration of this flight may be attri-
buted in part·to satisfactory closing off of the aperture. In addition to
-36-