Frequently Asked Questions ?
Q: Non-rigid Airships or Blimps.
A:
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, . This figure is on the safe side, and allows for variations
in altitude, temperature, humidity, and also purity of the helium.
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.
How high can it go ? Free from a tether the blimp will travel up out of sight. Our systems are designed to operate either positively or negatively buoyant 0-500 above ground. The FAA has guidelines for operating a " free balloon " ( meaning a positively buoyant object ). Here they are:
Federal Aviation Regulations - Part 101.0 - Moored Balloons, Kites, Unmanned Rockets, and Free Balloons
101.11 Applicability - This subpart applies to the operation of moored balloons and kites. However, a person operating a moored balloon or kite within a restricted area must comply only with 101.19 and with additional limitations imposed by the using or controlling agency, as appropriate.
101.13 Operating limitations - (a) Except as provided in paragraph (b) of this section, no person may operate a moored balloon or kite- (1) Less than 500 feet from the base of any cloud; (2) More than 500 feet above the surface of the earth; (3) From an area where ground visibility is less than three miles; or (4) Within five miles of the boundary of any airport.(b) Paragraph (a) of this section does not apply to the operation of a balloon or kite below the top of any structure and within 250 feet of it, if that shielded operation does not obscure any lighting on the structure.
101.15 Notice Requirements - No person may operate an unshielded moored balloon or kite more than 150 feet above the surface of the earth unless, at least 24 hours before beginning the operation, he gives the following information to the FAA ATC facility that is nearest to the place of intended operation: (a) The names and addresses of the owners and operators. (b) The size of the balloon or the size and weight of the kite. (c) The location of the operation. (d) The height above the surface of the earth at which the balloon or kite is to be operated. (e) The date, time, and duration of the operation.
101.17 Lighting and marking requirements - (a) No person may operate a moored balloon or kite, between sunset and sunrise unless the balloon or kite, and its mooring lines, are lighted so as to give a visual warning equal to that required for obstructions to air navigation in the FAA publication +Obstruction Marking and Lighting+ (b) No person may operate a moored balloon or kite between sunrise and sunset unless its mooring lines have colored pennants or streamers attached at not more than 50 foot intervals beginning at 150 feet above the surface of the earth and visible for at least one mile.(Amdt. 101-4, Eff . 8/20/74)
101.19 Rapid deflation device - No person may operate a moored balloon unless it has a device that will automatically and rapidly deflate the balloon if it escapes from its moorings. If the device does not function properly, the operator shall immediately notify the nearest ATC facility of the location and time of the escape and the estimated flight path of the balloon. Sub . C-1
If the blimp is stored between jobs, how long can you use your blimp before having to refresh the helium ? The envelope membrane permeability is the key here. About once a week, you should go and top off the blimp with a little helium.
Do you see what the Blimp sees? Yes, we transmit a real time video signal and view it on a monitor.
Is the wind a factor ? Yes definitely, relative to the Ultra-light Industry, it you fly ................so will I!!
What factors affect buoyancy ?
EQUATION: VOLUME IN CUBIC FEET = 4/3 (3.14159)(R^3)
TEMPERATURE: TEMP. + LIFT -
THE LOAD CAPACITY CHANGES THROUGH TEMPERATURE INFLUENCE: FOR EACH DEGREE CELSIUS CHANGE, LIFTING CAPACITY CHANGES AROUND 1/273 IN REFERENCE TO TOTAL VOLUME. THE PROCESS PROCEEDS CONVERSELY PROPORTIONALLY, I.E. LIFT IS REDUCED IN HOT WEATHER AND INCREASED IN COLD WEATHER. OR PUT ANOTHER WAY, WHEN THE OUTSIDE AMBIENT AIR TEMPERATURE RISES ABOVE THAT OF THE BUOYANCY GAS, BUOYANCY OF THE GAS IS EFFECTIVELY LOWERED, THUS REDUCING THE CARRYING CAPACITY OF THE AIRSHIP
BAROMETRIC PRESSURE: PRES + LIFT +
WE ASSUME THE LIFT OF HELIUM AT A BAROMETRIC READING OF 760MM MERCURY TO BE 1,1 KG/M^3. ON THE FOLLOWING DAY A PRESSURE OF 770 MM IS READ ON THE MERCURY BAROMETER. THE LIFT OF A CUBIC METER OF HELIUM TOTALS NOW 770/760 - IT HAS BECOME THEREFORE LARGER. SIMILARLY THE LIFT DECREASES IF THE AIR PRESSURE FALLS. E.G. 750/760.
PURITY: PURITY - LIFT -
AN IMPORTANT ELEMENT OF LOAD CAPACITY IS THE PURITY DEGREE OF THE CARRYING GAS. PER 1 % POLLUTION EMERGES ON THE AVERAGE A LOSS OF LOAD CAPACITY A LIKEWISE 1 %.
LOAD CAPACITY: LOAD + LIFT -
THE WEIGHT OF AIR TOTALS ABOUT 1,275 KG/M^3 @ 15 DEGREES CELSIUS AND 760 MM OF MERCURY. THE LIFT ( LOAD CAPACITY)OF GASES IS FOUND WITH A SIMPLE SUBTRACTION OF WEIGHTS, SO FOR EXAMPLE, HYDROGEN 1,273 KG MINUS 0,088 KG YIELDS 1,187 KG LIFT PER M^3.
DENSITY/DIFFUSION: DENS. - LIFT +
THE DENSITY OF A GAS EFFECTS LIFT AS WELL, THE LOWER THE DENSITY THE GREATER THE STATIC LIFT. DIFFUSION TAKES PLACE AS THE AMBIENT HEAVY AIR OUTSIDE PERMEATES THE GAS ENVELOPE AND MIXES WITH THE BUOYANCY GAS, THUS INCREASING IT'S DENSITY AND THEREFORE LOWERING IT'S CARRYING CAPACITY. THE DIFFUSION PROCESS IS ALSO INCREASED WHEN THE AMBIENT AIR HAS A HIGH HUMIDITY, RAISING THE DENSITY OF THE BUOYANCY GAS STILL FURTHER.
ALTITUDE: ALT. + LIFT -
AS AN AIRSHIP GAINS ALTITUDE, THE AMBIENT AIR PRESSURE OUTSIDE THE HULLS DROPS, CAUSING THE INSIDE PRESSURE OF THE BUOYANCY GAS TO RISE. THE GAS EXPANDS TO FILL THE BALLOON ENVELOPE UP UNTIL SUCH A POINT THAT THE ENVELOPE RUPTURES, OR MEASURES ARE TAKEN TO REDUCE THE PRESSURE. THE OPTIMUM CEILING OF OPERATION FOR AN AIRSHIP, WHERE THOSE PRESSURES ARE BALANCED IS KNOWN AS PRESSURE HEIGHT.