Xaos-21
The
Details
The
Xaos-21 (Chaos Twenty One)
Warning! Minimum of 500
jumps experience is required!
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.
**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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