roswell

An electrically operated needle ~lve was included in the order,
however it is to be ca~celled as the mechanical valve appears more feasible
to the manufacturer.
As the motor switched modulator ~us already i~ experimental
state of manufacture for the Signal Corps and Evans Signal Laboratories
an order was placed for 3 of them with these characteristics:
To have a motor-driven commutator to contain 4 contacts alternately
switching two different temperatures, pressure and a reference. Rate of
switching will complete one cycle per minute. To report pressure accurately
between 150 and 500 mb. with a pressure resistor to be of such a valve that
with a large r~diosonde frequency variation for a small change in pressure.
To have an adjustable contact variable between '50 mb and 400 mb
with a factory adjustment of 300 mb. When the pressure arm reached this
contact, a squib will cut a thread that holds the ballast diaphragm open.
The first mechanical dribbler vras received on 20 J..pril 1947 anci is
undergoing modification and tests before being flown on Cluster Flight #2.
If it is successful, an order for improved models will be placed.
Another method maintaining a balloon at constant altitude
is by replenishing the hydrogen in the non-extensible envelope as it is
valved or a.s it diffuses. This might be accomplished by use of liquid
hydrogen but not by use of chemicals. due to their great weight relative
to the small volume of hydrogen generated. The liquid hydrogen method
is being investigated with a long range view. It does not seem too
feasible, however, due to the difficulties of keeping the rate of eva-
poration of the liquid hydrogen low at the high altitudes, without ex-
tensive ani heavy guard llasks of ljquid air.
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