AIRSHIP
FAQ :
airship (air-ship)
-
Definition :- aircraft consisting
of a cigar-shaped balloon that carries a propulsion system (propellers),
a steering mechanism, and accommodations for passengers, crew, and
cargo. The balloon section is filled with a lighter-than-air gas-either
helium, which is non-flammable, or hydrogen-to give the airship
its lift. The balloon maintains its form by the internal gas pressure
in the nonrigid (blimp) and semirigid types of airships; the latter
in addition has a rigid keel. The rigid type maintains its form
by having a metal framework that holds its shape regardless of the
internal gas pressure; inside the hull are a number of small gas-filled
balloons. The first successful power-driven airship was built by
the French inventor Henri Giffard in 1852. Count Ferdinand von ZEPPELIN
of Germany invented the first rigid airship, which was completed
in 1900. The German airship Hindenburg burned at its mooring mast
at Lakehurst, N.J., in 1937. No rigid airship survived World War
II. Modern blimps are used in antisubmarine warfare, television
photography, and advertising.
Q: What Kinds of Airships are there?
A: There are three main categories of airships, Rigid, Semi-Rigid,
Non-Rigid.
.Rigid Airships
As their name implies, rigid airships have an internal frame. The
rigid structure, traditionally an aluminium alloy, or duralium creates
the form of the airship. The design was also to create a more aerodynamic
shape. In general rigid airships are only efficient when longer
than 120 Meters (360ft.) Because a good weight to volume ratio is
(or was) only achievable for large airships. For a small airship
the solid frame would have been too heavy. The R101 and R100 departed
from traditional lines of following Zeppelin airships, in that they
were far more aerodynamic than the standard Zeppelin pencil type
shape.
Semi-rigid Airships
Semi-rigid airships were more popular earlier this century. They
usually comprise a rigid lower keel construction and a pressurised
envelope above that. The rigid keel can be attached directly to
the envelope or hung underneath it. The airships of Brazilian aeronaut
Alberto Santos-Dumont were semi-rigids. The most famous representatives
of the type were the Norge and the Italia, the airships which General
Umberto Nobile used on his attempt to reach the North Pole. The
British purchased one ship from the Italians - the SR1.
Non-rigid Airships or Blimps
Non-rigid airships, also known as Blimps, are the most common form
nowadays. They are basically large gas balloons. Their shape is
maintained by their internal gas pressure. The only solid parts
are the passenger gondola slung beneath the ship, and the tail fins.
All the airships currently flying for publicity use are of that
type; the Goodyear Airships, The Lightship Airships seen as the
Budweiser and the Metlife Blimps in the USA, and the Fuji Blimp
in Europe. Many of these ships are always remembered and referred
to as their advertising which they carry, and not the manufacturer.
Q: Where does the term "Blimp" come from?
A: The popular story is that during World War II, a military
general visited one of the many airship stations operated by the
U.S. Navy. Trying to find out what material an airship was made
from, he tapped his finger against the fully pressurised envelope
of a non-rigid Navy airship. The general described the sound he
heard, "blimp," and blimps have been called blimps ever since. However
the contrary story is that the "Airships or Balloons" were classed
a "B" category and non rigid, hence "limp". So they were "B"Limp
class.
Q: How fo airships actually Fly?
A: Why airships fly is explained by the Principle of Archimedes:
"Bodies submerged into a fluid receive from it a lifting force which
is equal to the mass of the displaced fluid." (This is the same
principle that explains why boats float on water.) The airship is
filled with a lifting gas (Hydrogen, Helium, hot air or natural
gas). The air in which the airship finds itself has a higher specific
weight than the lifting gas. The envelope filled with the light
gas generates a lift that is equal to the weight of the displaced
air. Like a (light) cork floating in (heavier) water, a helium or
hydrogen filled balloon floats in the heavier air.
Q: What is the Lift of Helium ?
A: As a rule of thumb, 1 cubic meter of hydrogen lifts 1.1
kilogram, 1 m3 of helium lifts 1 kg. These figures are on the safe
side and allow for variations in altitude, temperature, humidity
and also purity of the helium.
Q: Can I get a ride on an Airship at Cardington
?
A: The answer at present is unfortunately usually NO. Despite
all the modern technology used in today's airships they are cost
effective only for advertising and aerial photography purposes.
In relatively small airships, passenger transportation is not profitable
enough unless it is combined with an advertising mission. In the
past, the small number of airship rides which is available has been
given to executives and clients of the advertisers/sponsors of the
blimps. Airship Industries in the UK ran a successful Passenger
scheduled service over London during 1982- 1990.
Q: I want to build an airship. Where do
I start?
A: Airships need to be "housed" and therefore you need to
design an airship which can fit in to and get out of the building
in which you are going to build it in. The recognisable airship
sheds of Cardington, Lakehurst and now Brandt in Germany are some
the largest buildings ever constructed to house the massive ships.
Remember : the size of the airship is dependent on the size of the
building you built it in !.
Q: Where can I find More Information?
A: If you check out the research centre on Airshipsonline.com,
then this should help answer your queries. The Links page to other
sites should give you a huge selection of other websites on the
net which can help. |
