How to construct a model dirigible
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Title (Dublin Core)
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How to construct a model dirigible
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Article Title and/or Image Caption (Dublin Core)
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How to Construct a Model Dirigible
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extracted text (Extract Text)
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THE model herein described is a
dirigible of the cylindrical type,
having semi-spherical ends. The ma-
terial used to construct the envelope is |
varnished silk. Its length is 6 ft. and
its diameter 13 it. The silk should be
coated with a thin varnish on the inte-
rior and exterior surfaces to increase
its gas-holding property.
The constructional details of the
cylindrical part of the envelope should
present no special difficulty. It is
best to build the cylindrical portion
of this model upon light cardboard.
Of course, it is essential at all times to
make allowances for overlapping when
cutting up the silk, both on the cyl!
inder and the strips making up the
ends. The semi-spherical ends may
be readily constructed by those famil-
jar with the development of curved
surfaces. For amateurs unfamiliar
with _pattern-drafting, the following
solution is offered.
The radius of the envelope being
9 in. and the plan being to employ
six strips to an end, we get the max-
imum circumference equal to approx-
imately 56.7 inches. Dividing the
circumference into six parts, we get
the base, AB, of each strip. These
measurements are laid out to scale
on pasteboard. Dividing the circum-
ference by two, we are enabled to get
the height, CD, of each strip. The
height is divided into nine equal parts,
as shown in the figure, and lines drawn
parallel to the base. The actual
length of the lines may be readily
ascertained by multiplying the deci-
mals in the figure by the length
of the base. Twelve similar strips,
with allowances made for joining, are
cut from the silk, using the paste-
board strip as a pattern. The envelope
being completed and permitted to dry
thoroughly, it is inflated with an air-
pump to ascertain whether any leaks
exist.
Assuming that it is intended to
inflate the model with hydrogen, which
has a lifting capacity about twice
as great as coal-gas, it is advisable
to procure a tank of the gas under
pressure. The metallic tank is return-
able, and the cost of the gas very
small. If coal-gas is used, it may be
necessary to obtain a small force-
pump to get sufficient pressure. A
small valve should be inserted at one
extremity of the envelope for purposes
of inflation.
In a dirigible of this size a high rate
of speed is impossible, and for ordinary
purposes undesirable.
As shown in the accompanying
illustration, the motor consists of two
twisted rubber skeins fastencd to a
spruce nacelle. The nacelle, which
should combine lightness with strength,
is made from spruce, although other
woods may be substituted. The na-
celle is slotted throughout its entire
length, as shown, to reduce its weight
‘without unduly decreasing its strength.
The thin guy-wires or threads should
be strung as shown to afford the most
efficient means of propulsion,
The propellers may be fashioned
from light wood or metal. They must
be arranged one in front and one
behind, both being securely fastened
to the nacelle by a pair of aluminum
guides. Since the actual speed of the
dirigible has nothing to do with the
model sustaining itself in air, the pro-
pellers should be large, though light,
and should revolve slowly. It is sug-
gested that they be constructed of
thin steel wire and varnished silk to
secure maximum lightness. They must
be of opposite pitch, and of the same
weight and size. The bead bearings
should be frequently oiled to reduce
friction.
As is the case when air resistance
must be taken into account, all of the
parts must be neatly and smoothly
finished to give the most satisfactory
results. —HERMAN NEUHAUS.
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Contributor (Dublin Core)
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Herman Neuhaus (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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1919-04
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pages (Bibliographic Ontology)
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124-125
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Rights (Dublin Core)
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Public domain (Google digitized)
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Archived by (Dublin Core)
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Davide Donà
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Marco Bortolami (editor)
Popular Science Monthly, v. 94, n. 4, 1919
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