Pressure Height: The height above mean sea level as determined fram
pressure measurements used in this work with the
N.A.C.A. Standard Atmosphere.
Section 4. Flight Techniques
The general techniques of preparing and launching controlled altitude
balloons are patterned after those of the smaller radiosonde balloons. The
treatment· of large • manned balloons has been studied. however • and inf'orme.tion
of considerable value has been gleaned; as from the National Geographic Society
. 11.12
reports of the flights of Explorer I and Explorer II , and from the book
15 13. 14
by Upson and Chandler • Fram these and other studies 'and from original
experimentation with General Mills advice, a satisfactory technique of' handling
controlled-altitude balloons has been developed.
A. Infh.tion
The lifting gas used for these lar~e balloons has been helium.
The choice of gas was made on safety considerations. Hydrogen, however,
has several advantages over helium. It will lift ~ more than helium and.
due to its lower specific gravity, requires but 50% of the ballast release
that helium requires to correct for disappearance of superheat at sunset.
Helium, on the other hand, leaks and diffuses at a rate but 70% that of
hydrogen. However • for long flights. hydrogen would prooably have more
over-all economy of ballast.
Inflation has been made through a low-pressure, diffusing manifold,
feeding from a number of' helium tanks simultaneously to the balloon. The
smaller balloons he.ve been inflated inside a .hangar, permitting very exact
weigh-off of the balloon's free lift, thus predetermining the rate of' rise
fairly well. The plastic balloons larger than 15 feet in diameter have
generally been inflated out-of-doors, aa no hangar large enough for interior
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