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 The
Xaos-21 (Chaos Twenty One)
Warning!
Minimum of 500 jumps experience is required!
About
our prices: Our price for the Xaos-21 in the 2001
Para-Gear catalog #66 is incorrect because we mistakenly
provided them with the wrong price schedule for
this canopy. The MSRP for all standard sizes of
the Xaos-21 is $2198.
The Xaos-21 is a 21-chamber
cross-braced tri-cell canopy and one of Precision
Aerodynamics' highest regarded ultra performance
wings. We weren't exactly really sure at first what
one rather analytical so-and-so meant when he firmly
uttered "The mysterious paradox is that the
Xaos-21 demonstrates the epitome of recalcitrance
as it rebels against the authority of the laws of
gravity, because it is only through the laws of
gravity that this machine flies at its best,"
but we think he meant "It likes to be loaded."
We have been manufacturing different versions of
cross braced tri-cells for several years, and the
Xaos-21 includes a number of refinements we have
made during our continuing research and development
of ultra performing crossbraced canopies.
You
don't have to be a NASA Pilot in the Space Program
to appreciate the awesome flight of the Xaos-21,
but after you fly it, you will think you are.**
Our
developmental program for the Xaos began in the
summer of 1999 and has continued for two years,
culminating in the most advanced airfoil we have
produced to date. The primary focus in our development
of this 3rd generation cross braced tri-cell airfoil
was to generate a true 3-D wing whose strong suit
centered on high speed swoops with a tremendous
reservoir of lift available to be unleashed during
the landing phase of flight.
Several changes would have to be implemented to
the existing technology in order to achieve our
final goal. Always present in a designer's mind
is the challenge to increase lift and reduce drag
at the same time in order to enhance speed and efficiency,
while paying mindful attention not to sacrifice
the details of pack volume and durability in the
process. The development of a superior flight required
a very detailed evaluation of each and every separate
element in the canopy's construction, with careful
consideration of the effects that any component
may have on the performance of another.
 Stabilizers
Evolve into Stabilribs
We began by evaluating one area has been overlooked
for many years by most all manufacturers, the stabilizers.
What do stabilizers really do? What are they supposed
to do? What do they stabilize? Why are they there?
Take a look at any existing canopy in flight and
ask yourself why the stabilizers aren't just called
"tacked on flappers" or "flailing fabric slider-stop
holders."
The general concept of what a stabilizer panel is
supposed to do was lost back around the time that
the slider was first utilized as a deployment-reefing
device on ram-air canopies. The original concept
for stabilizer panels was to minimize the effects
of wing tip vortices of a canopy, effectively increasing
the virtual aspect ratio for any given design.
That was all fine and good, and stabilizers on early
ram-air canopies did just that, in theory. Then
along came the slider, and while the slider did
get us away from pilot chute controlled reefing
and all of its associated malfunction modes, it
was quickly discovered that the slider could cause
considerable canopy damage if some protection were
not installed between the slider and the canopy.
Voila, along came slider-stops. In the beginning,
slider stops were made from all the old reefing
rings that were now no longer necessary, and they
were abundant, but they were not cheap. They still
cost about a dollar each. As I recall, one enterprising
canopy manufacturer began sewing half-dollars into
the stabilizers to serve as slider stops, thereby
cutting his cost in half. Except for the half-dollars,
stabilizers remained pretty much unchanged for many
years, and to this day the stabilizers still provide
a convenient place for a canopy maker to install
slider stops.
In many instances, however, the shape and attachment
method of stabilizers has historically been a subset
of the preferred placement of the slider stop (and
subsequently the opening characteristics), and less
associated with the canopies flight performance
. Stabilizers on more than 99% of canopies flown
today are installed as a separate piece of fabric
holding the slider stop, and simply tacked onto
the end-cell suspension line, left flailing in the
breeze at full flight and creating significant amounts
of drag.
With the Xaos-21, as well as other Ground Zero canopies,
we have instituted a technology that we refer to
as a "Stabilrib", integrating the stabilizer panel
with the end rib as a solid piece, and attaching
the outboard suspension lines to the bottom of the
Stabilrib instead of the lower surface of the canopy.
By designing and constructing the canopy this way,
several things happen, and all of them are good.
First, the suspended load imposed on the end cell
is evenly distributed throughout the chord of the
wingtip, resulting in better airfoil performance
during all flight modes. Diffusing the end cell
loading throughout the chord also eliminates the
inefficient point loading of traditionally built
canopies, and puts the Stabilrib to work full time,
producing more efficient flight at full glide, creating
a positive control point during quick turns, and
channeling airflow more efficiently across the lower
surface generating a more powerful flare.
 Drag
Reduction, Higher Flight Speed, Dynamic Performance,
and Line Durability...
A Win-Win-Win-Win Combination
Another area of concern in the development of the
Xaos and other Ground Zero canopies was to find
a material to use in suspension lines that would
not only yield a lower coefficient of drag but also
a material that could tolerate the friction of the
slider for the duration without detrimental effects.
For years, parachute designers have utilized a myriad
of synthetic fibers and geometric braids in search
of the elusive perfect material for parachute suspension
lines. Nylon had been used for many years in round
canopies, and it worked well in those designs, but
Nylon is not suitable for use in ram-air canopies
because of its elongation (stretch) properties.
Dacron (polyester) became the fiber of choice early
in the development of ram-air canopies. Polyester
braid is stable, and although it does stretch considerably
during deployment, it has a good memory and therefore
retains its original dimension much better than
Nylon. The only real downside to polyester braid
is that it is relatively bulky when compared to
some of the newer line materials like Spectra and
Vectran.
Spectra became popular as a low bulk option for
some ram-airs, and many tens of thousands of ram-air
canopies have been rigged and jumped utilizing Spectra
braid. Some of the early braids of Spectra, however,
proved to be unsuitable for use in some parachutes
because of the significant shrinkage of Spectra
fiber as a result of the friction of the slider
grommets. This shrinkage is most evident in a canopy's
control lines and end cell outboard suspension lines.
The resulting trim degradation is slow to onset,
and many jumpers do not notice it as any specific
change in performance on any particular jump, but
rather degradation in performance over a period
of time. We have seen some spectra-lined canopies
in need of an entire replacement line set with fewer
than 300 jumps.
Vectran fiber appeared to be a very real option
for parachute suspension lines when it was first
introduced in 1999. The braid geometry was stable,
and the bulk was only a tad bit more than Spectra.
The best part was that Vectran did not suffer from
the friction-induced shrinkage that users of Spectra
had experienced. As a matter of fact, the melting
point of Vectran fiber is high, and Vectran braid
is difficult to cut with a traditional hot knife,
while the same braid of Spectra line can be nearly
be cut with a hot knife when waived over the line
like a magic wand. Early indications in controlled
testing indicated that Vectran would be a strong
replacement for the popular (but unstable) Spectra
braid.
Unfortunately, the results of controlled testing
for durability of Vectran line were not manifested
in Vectran's widespread and common use. On more
than one occasion, a Vectran control line would
snap at the most inopportune time (on the landing
flare) and with high performance canopies, this
is absolutely not acceptable. Users of canopies
with Vectran line must inspect their canopies before
every jump, and monitor the wear of both the suspension
lines and the control lines.
With the Xaos-21 and other Ground Zero canopies,
Precision is utilizing a fiber known as HMA for
suspension and control lines. HMA is an acronym
for High Modulus Aramid fiber. Our experience during
the past two years indicates that HMA line not only
packs smaller, it also tolerates the slider's friction
quite remarkably, while at the same time retains
its linear stability as well as Vectran. Xaos-21
canopies (and other Ground Zero canopies) each contain
three different sizes of HMA line including
352, 440, and 946-pound tensile strengths. The braided
diameter is smaller than either Spectra or Vectran.
Continuous Suspension Lines
We have outfitted the Xaos-21 and other Precision
Ground Zero canopies with continuous suspension
lines. By eliminating the suspension line cascades
we have done several very important things. We have
eliminated a library of malfunctions associated
with cascaded suspension lines, we are able to use
a much smaller diameter suspension line (less drag),
we have minimized the front riser pressure while
enhancing riser flight control on both front and
rear risers.
Lateral Reinforcement Bands
Some
people who have closely inspected the Xaos-21 have
noticed and commented on the addition of lower surface
lateral reinforcement bands. It is interesting to
note that the general impression is that these bands
are intended for opening integrity, and while that
may certainly be true, the real reason for spanwise
lower surface reinforcement bands is flight stability,
especially during radical flight maneuvers. The
spanwise lower surface reinforcement bands allow
the airfoil to retain its proper 3-D shape during
all phases of radical canopy flight.
The Refined Leading Edge
One of the least noticeable, but most significant
changes in the Xaos-21, is the refinement of the
canopy's leading edge. We spent months on this small
but important element of the Xaos airfoil. Take
a close look at the shape of the Xaos leading edge
as compared to other cross-braced canopies available.
While it is not so apparent in full flight because
of typical speed distortion, the refined leading
edge of the Xaos-21 airfoil explodes dynamically
into play throughout the entire landing phase of
flight, while it works in concert with each of the
previously mentioned enhancements (Stabilrib technology,
HMA fiber braided suspension lines, continuous line
geometry, and lateral lower surface reinforcement
bands) to deliver an ultra-performance canopy flyer's
dream... an ultra performance canopy flight that
defies gravity.
Wrap-Ittm
Soft Links
Wrap-It tm
Soft links are standard.
**Warning
!! Minimum Experience Requirement for Xaos-21
The Xaos-21
is one of the highest performance wing we have produced
to date. Please do not purchase or jump this canopy
before you have a minimum of 500 elliptical ram-air
jumps experience within 15% of the manufacturer's
Maximum Operating Weight Limit. Maximum Operating
Weight Limitations for the Xaos-21 are absolute.
Do not exceed these limitations under any circumstances.
Severe bodily injury or death may result in exceeding
these limitations of experience and/or wingloading.
Prudence and good judgment dictate that your chances
for long term survival and happiness under this
canopy require that you observe and follow these
limitations.
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