Basejumper.com - archive

Definition: Skirt sag: the distance midway between reinforcement tapes to skirt reinforcement tapes to skirt.
What is:
The size of your PC(s):
Small or big mesh?
Skirt sag?
Me first.
Size: 36"
Mesh: small
Sag: 0.7"

The idea of this post is to get an idea of the norms.
Please do not post the name of the manufacturer.
I will play with this in MSexcel and post the results.
Thanks in advance,
take care,
space

why all the interest in PC sizes and stuff lately?
Are you trying to figure out something about the poor soul who lost his life recently at the ITW?

I was wondering if had something to do with large parachute in smaller(ish) container? And very tight pin tension because of the larger pack volume?

Just some thoughts?

Rest IN Peace Bro.

My interests in PCs go a long way back. I was the 1st one to have zero-p for BASE PCs. Digging thru PD´s dumpster for scraps because they would not sell any.
I´ve witnessed BASE 8-9000 jumps and saw what crappy PCs can do. Also experienced it first hand.
It is my nature to pass on what I have learned.

As for the incident you speak of, this is not directly related other than he had a PC. Also, it was not tight pins that contributed to the incident.
Take care,
space

Nice.

Much appreciated.

What might your theories be on the ITW incident, was it maybe a crappy PC?

Post your skirt sag in return please.

From the "incidents" on this forum I wrote this:
"We could not find the "smoking gun". By this I mean that we were not able to recreate the scenario that led to the fatality. The most obvious thing from the police photographs was that the bridle shrivel flap was compressed. This is normally used in conjunction with wingsuiting. Manu was doing a tracking jump with a wingsuit modified bridle."
Being a connoisseur of pilot chutes, I do realize that I find many PCs in a despicable state of construction and/or attachment. How much leeway in skirt sag and stability we simply don't know. The fact stands that no one has died from too big of a PC. (correct me if needed). Not only, was I friends with # 10 on the list, (36" PC on a 500fter) I have another friend jumping a 46" on jumps between 100 and 1800m. Sub-Terminal to Terminal openings and has not had a prob. Center cell strip? Happens on every opening with a PC or PCA. skydiving pods, tailpocketed or free packed.
Not a prob, just an excuse IMHO.
Hope this helps.
Post your skirt sag.
take care
space

 
36" ZP vented, big mesh, 6 load tapes, low jumps (<20)

3 measurements at different locations:

1 1/4"

1 3/4"

2"

Okay, I worked hard today packin rigs (2) and measuring my arsenal of 2 spoke PCs (5) while kids were blasting me with supersoakesr at my apartment’s playground.
What I found was quite interesting. Big mesh has 2 big sags and 2 little ones. One was just totally freaky.
In the MSExcel file I have attached, I took the average of 4 measures between the reinforcement tapes and sag. Then divided it by the radius and multiplied the diminutive to the finished size giving the “ Has drag like a” value.
Disclaimer: These are spur of the moment calcs. And as you can see from PC #3 symmetricality is not taken into account. If any one has a better calculation let me know.
Take care and know your gear
space

Size
# spokes
Mean Sag
All large mesh

38" ~125 jumps
2 spokes
3.5" (8.9cm)

42" ~50 jumps
3 spokes
1.75" (4.4cm)

42" ~75 jumps with several water jumps
3 spokes
1.75" (4.4cm) (max 2" (5.1cm) / min 1.5" (3.8cm) - I expected more variation from the water jumps but it looks pretty good)

48" ~40 jumps
4 spokes
2.25" (5.7cm)

52" ~10 jumps
2 spokes
2.75" (7.0cm)

In addition to average sag, I'd be interested to hear the difference in sag between sectors.

Teaching now, but I'll try to measure a few (or more) of my PC's later this week.

Sag range was <.75" for all. It was very consistent.

Here's my current stable (measured in 2-3 different places for each one):

Size: 32" (ZP, 6 spokes, vented, new)
Mesh: large
Sag: 1.5" everywhere

Size: 32" (ZP, 6 spokes, vented, 50 jumps, same mfg as above)
Mesh: large
Sag: 4" to 4.75"

Size: 38" (ZP, 4 spokes, 50 jumps)
Mesh: large
Sag: 3.25" to 3.75"

Size: 42" (F-111, 6 spokes, 50 jumps)
Mesh: large
Sag: 1.5" to 2.25"

Size: 42" (ZP, vented, 6 spokes, 25 jumps)
Mesh: large
Sag: 1.75" to 2"

Size: 42" (ZP, vented, 6 spokes, 25 jumps, same mfg as above)
Mesh: large
Sag: 2" to 2.25"

Size: 48" (F-111, 8 spokes, 50 jumps, mostly S/L)
Mesh: large
Sag: 1.5" to 3.5" (double-checked this, but it seems to be accurate)

Size: 48" (ZP, 8 spokes, 10 jumps)
Mesh: large
Sag: 2" to 3.5"

Michael

Did you ever come to any conclusions with this info?

yes. Block constructed PC sux by 30% drag. orbiting pc doesnt pull it 100%. it is tangential. example test;pull a car straight up. then pull 45 deg off the line. I speak with experience. Maybe I can get the police to publish my reports. 2 out of 3 were due to pc issues.
ask more. or better, google it.
tcs

Have you gotten your hands on the squirrel pc? How do you think it would compare?

No squirrel PC exp. But i have done a lot research in this area meaning that i have jumped nasty PC. I have been playing with differing planforms for pc.I maybe the reason that one does a sym check onthe pc.
I preached this. Game on means no bridle twists.
I must go now away. I do some supersonic rigging for the st leonhardy
tcs

We had some prototypes here this summer, but I haven't yet seen the production version. I'm very interested to see how the final product turned out.