Where to find pack volume charts?

can anyone point me to a web page that will give canopy pack volumes for different manufacturers? i am looking specifically for the spectre 120 and 135 pack volumes. thanks

thanks for the help levin. blue skies.

Hmmm... a lot of the numbers on the ParaGear chart don't match what the manufacturers' list for pack volume - 321 cu.in. sounds kinda big to me for a 7-cell 120, but what do I know? (not much) Anyway, I'd probably call the manufacturer - at least that way you'll have someone to blame when nothing fits right bsbd, Keely M.

Many of the numbers on the Paragear chart come from the PIA study, where they dumped canopies in a cylinder with the nose exposed, tossed 200 pounds on top, and saw how they settled. These numbers seem consistant with reality, where a 375 cubic inch Monarch has bits hanging out of a 350 cubic inch Reflex bag.

Some of the manufacturers' numbers reflect what could be made to work.

Other numbers were probably obtained using incomplete canopies that didn't yet have all their fabric and/or lines, like Precision's claim of 302 cubic inches (100 foot elliptical territory) for the Monarch 135 (which takes a closing loop 2' longer than a Stiletto 120 which measures about 325 cubic inches).

Historically, canopy makers have exagerated. If you accept some of their numbers, you'll end up with a rig two sizes too small.

Talk to the rig manufacturer and look on the PIA chart if you are curious about an older canopy design.

That's probably about right.

I called Performance Designs. They do not have published pack volumes for any of there newer canopies including the Spectre and Stiletto. The place to call is the manufacturer for the container that it is going in. If a container manufacturer does not have a pack volume for a particular canopy, then they can call the canopy manufacturer for a demo to obtain it. Blue Ones, Levin http://www.flyvertical.com

I think they are written in FantasyLand. Maybe you should check with disney or Micheal Jackson.

It may be not so much that the mfg exaggerates. It may be a difference in climate. Most of the volume measurements are done in humid climates (FL, TN) When you bring those canopies out west, everything will be too tight.

I always send my reserve directly to the rig mfg, to get it sized appropriately AND I ask them to go up one size to account for the arid climates I jump in.

I printed this out thinking it's really cool, then I read it a bit more.

Can anyone tell me why the difference between a Tempo 170 and Tempo 150 is 101 cu.in., while the difference between the 150 and a 120 is only 27 cu.in.?

Blues, Dave

Several years ago, we at Precision Aerodynamics measured the pack volume on every canopy we produced for almost an entire year. We measured every canopy two times: First, the complete airfoil section of the canopy before the lines were installed, and Second, the same complete canopy after the lines were installed. I did a presentation at PIA Symposium where I discussed the details of this massive study.

All canopies were measured by the same person. Pressure and Humidity were not scientifically controlled, but the production area at Precision is air conditioned and were temp and %rh were monitored and documented. After studying pack volume variances for many months, the bottom line was (and is):

Variance in canopy airfoil volume [the fabric portion] of similar models is minimal*. Variance in complete canopy volume (with lines installed) can be huge. By far, the largest variance in pack volume is directly related to three things. The first two things are able to be monitored or controlled, which we did. The third factor is a material function. In order of magnitude, these factors are:

1. Packer (or in this case, the person loading the chamber) Experience and consistency are mandatory. 2. Percent Relative Humidity: Low RH = Big Pack Volume 3. Line Set Bulk: This came as a big surprise in our study, but it was an apparent trend early on in the study. The variance in line set bulk for line sets cut from different lots of the same material (Spectra, Dacron, Kevlar [before Vectran's time]) was staggering.

I have literally reams of documentation containing the details of this study, and those details were a real eye opener to many people in our industry, including myself. Line Set Bulk... Who would have ever thought THAT was the culprit!

*There is one significant exception to the discoveries in this Precision Aerodynamics' study, and that involved canopies which were produced during a certain time window in the 1980s from fabric used by most all parachute makers of the time, and that fabric was sold under the brand name of Harris F-111, a material that hasn't been produced for parachutes now for over a decade (although many people still refer to it generically) That particular era of F-111 production we dubbed as having a 'Mystery Bulk Condition', a tongue-in-cheek reference to certain parachute fabrics during the same era that suffered from a condition known as the 'Braided Warp Condition'.

George Galloway Precision Aerodynamics, Inc.

[snip the rest]

Varying line bulk. I wouldn't have guessed that. Interesting. Any variance related to different colored dyes?

Blue Skies,

Marc

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