Main & reserve canpoies

[freefaller76 0]

This may seem like a stupid question, but what is the difference between main and reserve canpoies? Are they built differently? Could you use a reserve canopy packed in your container as your main? The reason I ask is because reserves seem to be cheaper than mains. What's the diff?

[Samurai136 0]

Reserves are built from F111 nylon material and they're all 7 cell canopies.

Most main parachutes are built from Zero-porosity nylon (ZP). The zp material is impregnated w/ a substance similar to silicone which keeps air from passing thru the material. This allows the designers to build a higher performance modern canopy.

Main canopies come in all shapes (7-cell/ 9-cell/ tapered, etc) and performance ranges. Some people are satisfied jumping a Raven reserve for a main but there are so many other choices out there. Why limit your self?

Ken

"Buttons aren't toys." - Trillian
Ken

[icutaway 0]

Ask yourself this question.

What would you like to drive more, a model T ,or a corvette?

Scroumptious P.O.L

[ZigZag 0]

Nice start to your question, right.
One would think that you'd get some decent answers
from your instructors, so do ask them, but here goes:
Most reserve canopies these days are seven cell
canopies built of low porosity fabric with a permeability of 0-3 CFM ( cubic feet per minute ), which is the fabrics qualility to pass air through its weave (simplified). Most people refer to this fabric as F-111, which was a trade name given to a fabric mfg'd by the Harris Mill some years ago. At this time there are still some 5-cell reserves in use, such as the Swift
by Paraflite, and also some 9-cell designs like the Predator (Chute Shop, South Africa). Most 9-cell designs used in the U.S. are tandem reserves.
You certainly can jump a reserve as a main, as was big fashion with the Raven series canopies by Precision Aerodynamics during the 80's and 90's. Some folks still do. Bear in mind that the Ravens, back then, were supplied with a bridle attachment point.
Tempo (PISA) reserves also were sold as mains for some time, the bridle attachment being custom added.
There is however the question of what kind of performance you are looking for. You can still buy low porosity (F-111) canopies, that are optimized as
mains, as the PD 9-Cell or even 7-Cell. But are you really going to get the most bang for your buck?
Enter Z-P fabric and designs on the cutting edge of technology (not to say that reserves haven't gotten better). Zero-P or Z-PO refers to fabric that is coated with urethane or other substances to make it impermeable. This improves pressurization of the airfoil, which results in better dynamics, especially when flaring in the landing phase. Z-Po will also last considerably longer, since the coating helps to inhibit UV degradation; nylon is the base material in both main and reserves, which is susceptible to UV. Generally you can buy 7-Cell or 9-Cell main canopies, of which there are crossbraced variants that enable designers to create stiffer and flatter airfoils with better performance characteristics,
kinda like a Formula 1 racing car.
You may want to consider buying a used Z-P canopy
that has been thoroughly checked by a rigger.
Often the used canopy may require a new line-set, depending on the number of jumps put on the canopy, but it would still represent a good investment
if the fabric and related components are in good nick.
Hope that gets you started.
Ziggy

[freefaller76 0]

Thanks, a big help! But for the newbie enquiring mind, answers inevitably lead to more questions! Why then would 7 cell F-111's be the most popular choice for reserves? Is it becuase they are cheaper to make and easier to pack? (I've heard that ZP canopies are harder to pack).

As for ZP, thanks for the info. I've only ever jumped student canpoies (Manta/Laser) which I believe are F-111. I hope to jump a ZP sometime soon and see what the difference is.

[gmnisson 0]

First the why 7 cell part. In general the wing shapes that are closer to square as opposed to a long rectangle are less subject to some malfunctions. The second about f-111 fabric. Reserves as opposed to mains must meet rigorous certification requirements. Those requirements as to load and speed at deployment make it harder for z-po fabrics that trap more air to both open quickly enough and maintain structural integrity.

“How are Maxwell House coffee and skydivers alike? Well; their both good to the last drop.” - George

[BlindBrick 0]

Quote

Reserves are built from F111 nylon material and they're all 7 cell canopies.

Most but not all. The Raven -MZ came with a ZP topskin and I've packed more than a few 9 cell reserves(the LAser 9 comes to mind).

-Blind

"If you end up in an alligator's jaws, naked, you probably did something to deserve it."

[phoenixlpr 0]

I think theres no benefit having ZP material in a reserve. They are not fequently used so they are near ZP anyway.

Reserve canopies have different requirments like open in 100m where both vertical and horioztal speed is 0 m/s.

There was a time when there were such canopies that used for both main and reserve like Maverick.