which get their shape only in cause of the pressure of the lifting-gas
inside the envelope are called
airships of the non-rigid type. All extensions, like the fins and
the control car, are attached to the envelope.
The driving elements are attached to the gondola/control car.
airships have a long tradition and were never totally droped out of
sight.(especially in USA) The
first blimps, which had been really suitable and do also exist in
'modern' versions in the present, were
invented by August von Parseval. (click
here for more information about Parseval-Airships)
One of the
most important elements of a non-rigid airship is the ballonet-system.
A ballonet is an airbag (one
or two of them) inside the envelope, which provided with air from
a blower or direct over ducts
from the propellers of the engine unit. The air could be removed from
the ballonet through valves.
The ballonets are used for:
lifting gas increases its volume in cause of higher temerature
or a lower airpressure, also decreases
its volume in cause of lower temperature or higher
airpressure. If an airship (without a
ballonet) is full of gas and also tight, which must be or
it won't be suitable, on the ground and
starts now, increases its altitude, so the lifting gas inside
the envelope will increase its volume
in cause of the lower airpressure in a higher altitude.
The envelope will burst or the gas
will leak through an overpressure valve. If you are going
to land this airship, the gas will
decrease its volume and the envelope will get slack and
there's no chance to control this
airship. Therefor you use ballonets filled with air inside
the envelope to regulate the changing
the airship has a front and aft ballonet you can also steering
the hight of an airship. For
example, if you fill the aft ballonet with more air (leak
some air out of the front ballonet),
the airship will become heavier in the rear part of the
envelope (air is heavier than helium),
the ship gets an inclined position (nose up). In cause of
the dynamic (from the engines),
the airship will increase its altitude.
airship can also be trimed through a front and aft ballonet.
elevation of the Parseval-Airship "PL VI", 1910
are the ballonets inside the envelope)
controling via front and aft ballonet, blimp (newer type)
is the air/ballonet in the front and the aft section)
advertising-blimps here in Germany today were build by the Westdeutsche
m.b.H. (WDL Luftschiffgesellschaft m.b.H.) at Mülheim/Ruhr
(near Essen). The WDL is building two
different types of blimps. (Information
about these types)
The ships are rented by companies (normally for one or two years)
and will be painted with the comercial logo.
At night there's the chance to make Night Sign - advertising. Therefor
are about 10,000 coloured lamps
attached to the envelope and controled by computer. (Only airship-type