Semi-rigid
airships are airships, which are a hybrid between a rigid airship
and a blimp. Because of
the keel construction below the envelope they are also known as keel-airships.
There are many parallels to the basic design of non-rigid airships,
but some advantages of rigid airships are also used in this hybrid
construction.
The main
characteristics of these airship types are:
- The
envelope, which contains the lifting gas, has also ballonets
inside. (Like a blimp)
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- A
rigid structure, build as a keel, runs mostly below the envelope
as a gangway (so you can walk over the mostly or completely
length of the airship) and is also used as a depot for freight,
ballast and fuel / oil.
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- The
gondola for crew and the passengers is attached to the rigid
structure, also the engines, which can be build into extern
engine gondolas
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- The
control elements (the fins with rudders and elevators) are
also fixed to the rigid keel, if possible.
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Because
of the possibility of a more specific attachment, for example of the
engines, there can achieved a more effective poweroutput. The gondola
is nearly vibration-free and the whole style of the airship is much
more rugged.
Examples
for semi-rigid airships are:
The
military-airships type "Groß-Basenach"
The
military-airship "M II" (1909-1912)
The
expedition-airships "Norge" and "Italia"
The
italian airship "Norge" ("Norway") masted in Oslo (1926)
The
italian airships "Norge" and "Italia", build by General Umberto Nobile,
were used for expeditions to the North Pole. The airship "Norge", build
in 1923/24, started its arctic expedition on May 11th, 1926. They
crossed the Pole - aboard was also the very famous polar explorer R.
Amundsen. The airship "Italia" started its flight on May 24th,
1928, but this trip went wrong. In a dramatic rescue operation some
of the crewmembers have been saved.
Characteristics
of the airship N1 "Norge"
Lenght
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348
ft (106 m)
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max.
Diameter
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64
ft (19,5 m)
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Volume
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671,000
ft³ (19.000 m³)
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Engines
/
Performance
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3
Maybach-engines /
245 HP each
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max.
Speed
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60
knots (113 km/h)
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The
adevertising airship of the Raab-Katzenstein aircraft-factory
&
the Parseval-Naatz-Airships
The
assembling of the "Trumpf"- Airship R.K.27 of the Raab-Katzenstein-
factory
at Kassel. Really nice to see is the gas filled envelope and
the
keel with the gondola and the engines. (1929)
The
airship R.K. 27 ,and also the airships D-PN 28, D-PN 29 & D-PN 30
are direct (but semi-rigid) followers of the Parseval-Airships,
which have been designed by Dipl.-Ing. Naatz.
The
"Odol"-Airship D-PN 30 of the type "Parseval-Naatz" in flight. (1932)
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