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Title (Dublin Core)
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New planes for ocean travel: steamship weather reports to aid skyliners
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Article Title and/or Image Caption (Dublin Core)
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Title: New planes for ocean travel: steamship weather reports to aid skyliners
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extracted text (Extract Text)
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Three new flying boats, designed for
nonstop service between New York and
Lisbon, Portugal, will take to the air
soon for test flights. Commercial counter-
parts of the Navy's “Flying Dreadnought,”
they have been built for a new company in
the transatlantic flying field—American Ex-
port Airlines.
‘When they are put into service next year,
world conditions permitting, these planes
will fly with the advantage of more com-
plete knowledge of weather conditions over
the ocean than has heretofore been avail-
able. This is because the steamship com-
pany of which the air line is a subsidiary,
American Export Lines, is already at work,
in codperation with the U.S. Weather Bu-
reau, making daily observations of weather
conditions over the sea.
The new planes, designed by Igor Sikor-
sky and built by the Vought-Sikorsky Divi-
sion of the United Aircraft Corporation, are
smaller than the 42-ton Clippers of Pan
American Airways, weighing only 25 tons
with a normal load. Capable of carrying
40 passengers on short hauls, the VS-44's,
as they are known, will have sleeping ac-
commodations and living quarters for 16
passengers on the 20%%-hour New York-to-
Lisbon run.
The weather apparatus which the steam-
ship company has installed on its three ships
plying between New York and Lisbon, the
Exeter, Excalibur, and Excambion, is simi-
lar to that used previously at land stations
of the Weather Bureau, and by the Navy, to
study air conditions in the upper levels. Its
installation, however, marks the first time
that such observations have been available
to the Weather Bureau from ships at sea
on a daily basis. The equipment itself is
supplied by the Weather Bureau, but the air
line supplies the meteorologists who use it.
The most important piece of this equip-
ment is known as a radio “sonde” or sound-
ing machine. Actually, it is an accurate
weather observatory and radio transmitter
combined, which weighs only two pounds.
In use, this device is first placed in a
conditioning chamber on the bridge of the
ship, where it is tested to see that it is
functioning properly, and calibrated so that
its recordings of upper atmospheric condi-
tions will be in proper relation to conditions
at sea level. Then it is attached by a cord
to the bottom of a helium-inflated rubber
balloon, five feet in diameter and six feet
high. Balloon and sonde are then released.
As the balloon rises, the transmitter, pow-
ered by a dry-cell battery and connected to
three recording devices within the unit,
sends out a steady stream of signals on
a wave length of 72.5 megacycles. These
signals are picked up by a receiver on the
ship, which automatically records the infor-
‘mation on a graph.
The signals continue to reach the ship
until the balloon has risen so high or has
drifted so far laterally that they become too
weak for the receiver to pick up. Recordings
have been made successfully from as high
as 68,000 feet, and over distances of 75
miles. In ordinary practice, however, 60,-
000 feet is about the maximum effective
range of the sonde, while the lateral dis- |
tance is controlled by atmospheric condi-
tions. It may take an hour for the sonde
to reach the point where its signals fade out.
The instruments within the sonde measure |
temperature, humidity, and height. For the
first condition, a thermocouple is used. This
is a device consisting of two strips of differ-
ent kinds of metal, fastened together in
such a way that temperature changes set
up slight electric currents between them.
The currents generated by the thermocouple
control one set of signals.
Human hair, preferably from the head of
a blonde female, is used to measure humid-
ity. This type of hair has been found to be |
more responsive than any other kind. When
the humidity increases, the length of the
hair increases; when the air becomes drier, |
it contracts. This expansion and contrac-
tion controls another set of signals.
The third instrument is a barometer.
This measures atmospheric pressure by ex-
pansion and contraction of hollow metal
wafers inside of which a vacuum has been
created to make them more responsive to
pressure changes. Since atmospheric pres-
sure is directly related to height, becoming
less the higher you go, a third set of signals
controlled by the barometer, interspersed
‘with the others, tells at what height each set
of recordings was made.
‘When the last of the soundings has been
received, the meteorologist takes the infor-
mation from the graph in the receiver and
sends it by radio to the Weather Bureau,
where it becomes available to anyone. This
work, therefore, will aid ocean-flying planes
of other lines as well as those of American
Export Airlines.
Radio sonde observations are at present
made once a day from each of the ships at
sea, usually about midnight. Then at noon
each day, a “pilot” balloon, three feet in
diameter and carrying no instruments, is
released. This is watched from the ship
with a theodolite, an instrument for measur-
ing horizontal and vertical angles, as it
rises. From the observed angles the meteor-
ologist can compute the wind direction and
velocity at various levels. This information
is also radioed to the Weather Bureau.
‘When a radio sonde is used over land, a
silk parachute is attached to it so that it can
be recovered and used again. When used at
sea, however, a complete instrument cost-
ing about $40 goes to the bottom as the
price of each set of observations.
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Contributor (Dublin Core)
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David M. Stearns (article writer)
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Language (Dublin Core)
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Eng
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Date Issued (Dublin Core)
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1941-11
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pages (Bibliographic Ontology)
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81-83
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Rights (Dublin Core)
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Public domain
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References (Dublin Core)
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VS-44
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Archived by (Dublin Core)
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Sami Akbiyik
Popular Science Monthly, v. 139, n. 5, 1941
