FireFly Balloonstm are made at The Balloon Works in Statesville, North
Carolina. More of a craftsman's workshop than a factory, The Balloon Works is
where all aspects of a FireFly Balloon are designed and crafted. It's a place
with the earthy, friendly smells of wood shavings, leather and wicker.
Everything that bears the Balloon Works name is made there and the engineers
still design the products in-house to ensure they're built to the exacting
standards that have been progressively developing since 1972.
Over 1200 separate inspections take
place during the construction of each balloon. Every piece - valves,
hoses, ropes, panels - whether fabricated in the workshop or not,
undergoes a rigid incoming first-piece inspection. Every fuel tank is
pressure-checked. Every roll of fabric is tested for tensile and tear strength,
porosity and color variations, and flaws in weaving, before it's labeled
airworthy. Each panel is inspected as it's sewn into its gore, and each
completed gore is again inspected as it moves from one sewing station to
another. Sewing machines are calibrated twice a day, every day, to ensure
consistent conformity with their sewing specifications. When each balloon is
finished, it's inspected again, fully assembled and inflated on the test field,
under flight conditions. This almost fanatical attention to detail results in a
quality-control program that is unrivaled in the ballooning industry.
Concepts Behind The FireFly Balloon
An Overview
The successful design of a modern
Hot Air Balloon is an engineering problem that must combine three distinct
components - an envelope, an engine and a carriage - into
an integrated, functional whole that is both safe and practical in its assembly.
The Balloon Works, with its trademark FlexNet Envelope, Mirage Burner and
Triangular Carriage has created the intelligent solution to this
problem - The FireFly Balloontm.
The Triangular Carriage
The Balloon Carriage is the most
complex structure of the entire system and presents the most challenging design
problems because of the variety of functions it must serve.
- It must provide a structure strong enough to carry its Certified static
and inertial loads safely.
- It must provide secure accommodation for the pilot and passengers during
the entire flight experience, particularly during landings.
- It must provide secure, logical and convenient locations for instruments,
fuel, plumbing and burner.
- It should provide a safe and secure storage area for maps, strikers and
tools.
- It should be flexible, lightweight and well-balanced.
- It should be easy and inexpensive to maintain and repair.
- It should be aesthetically pleasing.
The equilateral triangle is the
most stable shape in nature and The Balloon Works has chosen it as the basis for
many aspects of their product. Most apparent is the Triangular Carriage which is
unique to The Balloon Works. For any given floor area, the triangle provides the
most stable base and longest sides. The three 60 degree angles provide maximum
floor space for pilot and passengers while storing the fuel cylinders, hoses and
instruments safely out of the way in the recessed corners. The ingenuity evident
in its construction is unsurpassed. The 9-ply birch hardwood floor is actually
cradled in a net of six aircraft ropes certified to lift 18,000 pounds. Securely
fastened to a central tie-plate by eye splices and protected from abrasion by
super tough plastic tubing, the suspension ropes run through hardwood skids, up
through the floor, up the carriage structure and out the burner supports to end
in an ultra-strong loop used to fasten the toggles at the end of the envelope
suspension ropes. The wicker carriage is woven with a tight, vertical weave,
well suited to resisting entanglement in branches or power lines. Horizontal
weaves can easily snag. A finishing urethane coating inside and out ensures the
wicker will resist drying out and becoming brittle or rotting from prolonged
exposure to moisture. This maintains the wickers ability to flex, absorbing and
distributing any bumps during landings.
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The Mirage Burner
The engineers at The Balloon Works, balloonists amongst them, developed
a set of criteria by which they would design their burner system.
- Burner Reliability - Both the primary liquid vaporization system and
the pilot burner must be highly dependable to minimize malfunctions and
flame-outs.
- Burner Output - To increase flight safety margins, the absolute
burner output must be extremely high.
- Flame Characteristics - The flame must be efficient and clean
burning, giving off a minimum of soot and radiant heat. The flame should
be shaped to minimize scorches and burns to the envelope.
- Mounting - The burner should be mounted so that the flame can be
precisely directed, it cannot tip over or pose a danger to the people in
the basket and it must be self-centering when the handle is released.
The fuel lines should be isolated to prevent catching on branches or
power lines. Passengers should be prevented from using them as support
during landings.
- Safety and Convenience - The burner should be comfortable to use and
fully operational with one hand. It requires a fast on-off response time
to reduce the likelihood of fabric damage during inflations and
landings. It must not permit the flame to wash back onto the pilot or
passengers.
- Redundancy - In the unlikely event of a major failure in the primary
burner, there must be an equally efficient back-up auxiliary system that
is powerful enough to climb, arrest a descent and allow a controlled
landing.
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The result is the Mirage Burner. It has the highest heat output certified for
balloon engines in the world - over 32 million BTU's at 240 psi tank
pressure. Propane is forced through thirty-three feet of vaporizing coil, enters
the flow guide to combine with air in a 60 to 1 ratio and is ignited upon exit
by three pilot lights producing a long intense, nearly invisible blue flame.
Pilot lights have their own pressure regulated fuel supply and the pilot flame
burns deep inside pilot burner stacks making it next to impossible for air
turbulence to extinguish them. Fire II was made more powerful and integrated as
the auxiliary engine with its own separate plumbing, valves, withdrawal lines
and burner outlets. Mounting on the uprights in a suspended tripod fashion
places all the burner controls in the center of the carriage, equidistant from
all sides or corners. Not surprisingly, the Mirage Burner and Fire II have
become two of the reasons for the popularity of FireFly Balloons.
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The FlexNet Envelope
Many modern Hot Air Balloons
employ a system of horizontal and vertical load tapes into which the stresses of
flight are transferred. Since these structures are rigid, the fabric panels of
the envelope carry some of the load. This is known as a skin-stressed envelope.
While not necessarily bad, it demands that heavier fabrics be utilized to
maintain the integrity of the system for safe flight. Manufacturers of this
envelope type tend to use nylon for its availability in heavier weights and its
initial strength. They also favor using folded seems to join panels to each
other and to the load tapes. The
Balloon Works opted for a different school of thought. There is an obvious
correlation between the volume of a balloon and its load lift capability. The
system itself, of course, comprises part of that load and the difference between
the system weight and its lift capability is what's left for the
payload. The best way to understand
a FireFly Balloon is to picture an orange with the segments running vertically.
In balloons, these segments are called gores and the joints between them are
called gore seams. In skin-stressed construction, a heavy web tape with adjacent
panels sewn to it forms this seam. It's called a load tape because the carriage
is suspended from it and the fabric stresses are hopefully transferred to
it.
The FireFly Balloon employs
the use of a pocket running the vertical length of the gore seam. Inside
the pocket, they've put a very strong and light rope, or load cord, which
is free to move up and down inside the pocket. The rope is shorter than
the seam and is attached at the top to the top girdle and at the bottom to
the bottom girdle. The girdles are structural members in that they receive
and transfer loads. Making the ropes shorter than the seams accomplishes
two things. It provides the beautifully rounded gore shape and it ensures
that the loads cannot be placed on the fabric panels. So, the only
function of the fabric envelope is that it holds the air and provides a
lifting
surface. | When
it came to the task of sewing each fabric panel to its neighbour, The Balloon
Works looked to a method of window construction that was used when glass was
rare and expensive to replace. The mullions in a window today tend to be for
aesthetics, but the original reason for this construction method was to isolate
individual panes of glass. If breakage occurred, it would affect the panes
individually and maintain the integrity of the whole, reducing the extent of the
damage and hence the expense of
repair. With Hot Air Balloons,
restricting the extent of damage is a matter of safety so the Balloon Works
developed the FlexNet Envelope Systemtm. In the
system, each fabric panel is surrounded by a strong tape and adjacent panels are
sewn into one side of the tape and not to each other. The tape acts as an
isolating member, as a mullion in effect, and if a tear occurs, it may travel
only as far as the tape before it either stops or is deflected back into the
panel. With damage thus minimized, the pilot may be afforded more time to make a
safer emergency landing.
The FireFly Envelope Valve
As a means of balloon deflation, the FireFly Envelope Valve, or
parachute valve as it is often called, is by far the most ingenious approach to
date. Its normal resting position is closed and it only operates by deliberate
and continuous action. It is automatically re-sealable, irrespective of how many
times it has been used, and no action is required to accomplish its closing
other than letting it alone. It's capable of proportional valving, releasing
huge amounts of air for deflation or small amounts for adjustments to vertical
flight. Its position at the top of the envelope prevents its dislocation from
snagging. How does it work? First, they put a hole in the top of the balloon
with a stiffener around it to act as a seal. Next, they fill the hole with a
fabric disc that's slightly larger than the hole. Attached to the perimeter of
the disc is a set of lines that connect to each other at a focal point below,
inside the envelope. This point is then attached to a rope which extends down to
the carriage to act as the control for the valve. Another set of lines connected
to the disc, are in turn connected to the envelope at the gore seams to limit
the downward distance of the disc. To prevent the valve from popping out the top
of the balloon, the load cords in the envelope (the ones sliding inside those
pockets) extend past their attachment at the top girdle and connect to a central
steel ring. The valve is held against this rope net with the push of the heated
air inside the envelope. By using some simple laws of physics, the valve
provides a venting capability and versatility superior to anything used before
it in ballooning.
Click here To learn more about FireFly Balloons.
FireFly, Mirage and FlexNet
are registered tradenames of The Balloon Works. The Balloon Works and FireFly
Balloons Logos are registered trademarks and are used here with the
permission of The Balloon Works of Statesville, North Carolina USA.
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