Reserve and Main

[hurrikanejae 0]

I just got into the sport about 5 weeks ago, and now that i have bought my own gear, i was wondering...what exactly makes a "reserve" chute, a reserve? is there any physical differences between my main canopy and the reserve itself, or are they identical?

Blue Skies Filled with Birdies,
Jeremy R. Marston

[phoenixlpr 0]

Quote

is there any physical differences between my main canopy and the reserve itself, or are they identical?

There was a time, where sport canopies were equal. There is some canopies can be used as reserve or as main, but latest designs has specialized a bit.

Most of the mains are made from ZP material with 9 or 7 cell with a bridle attachment point.

Reserves are made from low-cf material only with 7 cell only and without bridle attachment point. Reserves are having more reinforcement and the main design goal is open fast, on heading and pack small. They are not designed for having several hundreds of jumps.

[DrewEckhardt 0]

Quote

I just got into the sport about 5 weeks ago, and now that i have bought my own gear, i was wondering...what exactly makes a "reserve" chute, a reserve?

It was tested acording to FAA protocols for strength, maximum opening time, maximum total speed and descent rate in the deployment configuration, etc. and has a label carrying the TSO (Technical Standard Order) it conforms to with maximum suspended weight and deployment speeds listed.

Quote

is there any physical differences between my main canopy and the reserve itself, or are they identical?

Although some parachutes have been marketed as reserves and mains (Precision Raven and Falcon) there are big differences between contemporary reserves and mains.

AFAIK reserves are all currently built with rectangular planforms, which are less likely to have opening issues than tapered/elliptical designs. Most modern mains have tapered planforms which can turn quicker and have lower stall speeds so they're more fun to fly and land.

Nearly all are low-aspect ratio seven cell canopies which open more reliably; although Precision's 9-cell Falcon is certified for use as a reserve. Higher aspect ratio canopies have a flatter glide which will get you back from a longer spot.

Nearly all are made of low-porosity fabric which performs as well as ZP when it doesn't have a lot of pack jobs on it (PD reserves must be sent in for inspection after 40 pack jobs or 25 uses), although Precision makes reserves with a ZP topskin. Higher performance canopies (the PD Excalibur) made of 0-3 CFM fabric and flown at contemporary wing loadings were only good for a few hundred jumps; while you can get thousands out of ZP fabric as long as you replace the lines periodically.

Modern reserves all have spanwise reinforcing tapes which keep the canopy from completely separating during an over-speed deployment (I saw one older reserve spin in after it split into 2 and 5 cell chunks and was pleasantly surprised that the skydiver survived). Some newer main designs especially in higher performance classes (Katana, Samurai, and I think Brian includes them on the Lotus) have span-wise reinforcing tapes to make for a rigid wing but most main canopies and older reserves don't.

[hurrikanejae 0]

thanks so much for both of your detailed and helpful comments. after 69 jumps, i still dont know what my reserve looks like, but after flying my main and reading your comments, i dont want to fly the reserve until i absolutley have to!

thanks again!

Blue Skies Filled with Birdies,
Jeremy R. Marston

[berchtoldaj 0]

but after flying my main and reading your comments, i dont want to fly the reserve until i absolutley have to!

[riggerrob 643]

Hint: borrow a Triathlon - the same size as your reserve.
That will give you a pretty good idea of how reserves glide, turn, flare, etc.

Also, ask your local rigger if you can look at an unpacked reserve.

[relyon 0]

Quote

There was a time, where sport canopies were equal. ...

... They are not designed for having several hundreds of jumps.

This appears to be in contradiction.

To my knowledge, the design (7 cell), airfoil, planform, material (F111), lines, and even trim for the PD reserve canopy series was identical to the PD main canopy series while the main series was still being manufactured. PD mains were used for hundreds of jumps, and while the reserves were/are used decidedly less, it's not that they couldn't be because of a basic design limitation.

I know plenty of CRWdogs who have 30-40 reserve rides on the same reserve who notice no difference whatsoever in flight characteristics or flare from the first jump to the most recent.

Bob

[DrewEckhardt 0]

Quote

To my knowledge, the design (7 cell), airfoil, planform, material (F111), lines, and even trim for the PD reserve canopy series was identical to the PD main canopy series while the main series was still being manufactured. PD mains were used for hundreds of jumps,

At wingloadings under 1 pound per square foot which few experienced skydivers do these days.

Quote

I know plenty of CRWdogs who have 30-40 reserve rides on the same reserve who notice no difference whatsoever in flight characteristics or flare from the first jump to the most recent.

30-40 is a lot less than "hundreds" and the wing loadings there are usually still moderate (1.3-1.4) by contemporary standards.

[relyon 0]

My point was that the statement that F111 7 cell reserves were "not designed for having several hundreds of jumps" is misleading. There is nothing about the basic canopy design (airfoil, planform, lines, material, etc.) that cannot accomodate that many jumps. I gave the PD main/PD reserve canopies as an example; there are others. Whether one wants to jump that kind of canopy that much is very different than whether or not it can be.

How a canopy is wingloaded in practice is an entirely different issue from what the canopy as a whole was designed for. All the F111 mains (and the reserves mentioned) beyond student status I'm aware of were loaded above 1.0 but below 1.5. All flew and landed just fine - repeatably.

Quote

At wingloadings under 1 pound per square foot which few experienced skydivers do these days.

As has been the topic of numerous posts, this could be a problem. While admittedly, reserve wingloadings less than 1.0 may be unnecessarily low, they can easily get too high as well. Trade a 79 sq ft 9 cell ZP pocket rocket loaded at 2.0 for a 99 sq ft 7 cell F111 reserve loaded at 1.6? A broken femur (or worse) following a "sucessful" save is embarassing ... at best. I'll pass.

Bob