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Tonto

Why....

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If 21 cell canopies have 21 cells, and 27 cell canopies have 27 cells, are 7 cell canopies not known as 14 cell canopies and 9 cell canopies not known as 18 cell canopies?

7 and 9 don't multiply by 2. Why do crossbrace multiply by 3?

t
It's the year of the Pig.

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If 21 cell canopies have 21 cells, and 28 cell canopies have 28 cells, are 7 cell canopies not known as 14 cell canopies and 9 cell canopies not known as 18 cell canopies?

7 and 9 don't multiply by 2. Why do crossbrace multiply by 3?

t

t



Um.... because the cross-bracing divides each "normal" cell into 3 smaller cells? :)
That's my guess and I'm sticking to it!
Mike
I love you, Shannon and Jim.
POPS 9708 , SCR 14706

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maybe because in english the same word describes a cell and a "cell".
In french there are 2 words :
cell : cellule : individual chamber
"cell" : caisson : group of individual cells which can be identified by the separation caused by suspension lines

My technical explanation is I think "understandable", and the reason why one or the other is just due to poor vocabulary/poor use of existing vocabulary.
scissors beat paper, paper beat rock, rock beat wingsuit - KarlM

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Because when you get to crossbraced designs, regular definitions suddenly don't apply anymore and you're free to make up new ones? Just my guess...:P

Or maybe it's because cells divided in two are 'regular' and cells divided in three are not...although techically, you could also call it 'quint-cell' since most crossbraced canopies have cells divided into 5 parts...

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I'll take a stab at the question with an educated guess.

Back in the day most parachutes had seven cells, with each cell being split into two chambers. PD developed the first commercially successful cross braced canopy called the Excalibur, with a three way split in each cell. By the standard convention of the day it was still a seven cell parachute, but as a marketing gimmick PD defined that as a 21 cell. When the rest of the industry caught up to PD with cross braced cells they followed the convention of dividing by three. It doesn't make sense, but marketing never really has to make sense.

So, that's my take on the question.
.
Tom Buchanan
Instructor Emeritus
Comm Pilot MSEL,G
Author: JUMP! Skydiving Made Fun and Easy

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since most crossbraced canopies have cells divided into 5 parts...

that kind of makes sense since they already have a 5 cell square. yeah, i know.. not common.. but whatever, names taken. i did not know a 7 cell square is actually a 14 (but i know about crossports and everyth... ok not everything!)
good question though. obviously, i know zeroooo about crossbraced canopies! but can i guess anyway? yay!

maybe they were just smarter about naming crossbraced canopies to avoid confusion in the future as they progressed. you know, call 'em what they are.

that's just my stab @ it... but if i'm wrong, remember both me and mike are both soooo new so be nice. (ok what do i win...:D)

cya t:)
edit of an edit: >Why do crossbrace multiply by 3?
i wanted to check back b4 i left and noticed i missed the last line in your post.
i have nooooooo clue. <<
i didn't lose my mind, i sold it on ebay. .:need a container to fit 5'4", 110 lb. cypres ready & able to fit a 170 main (or slightly smaller):.[/ce

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Would you really pay $2000 for a 7 cell canopy? :ph34r:




Hell no, that is $286 a cell! :P:P:P

In the carpet cleaning business - they say companies that call the work they do "textile restoration" can charge more...

So, what is a fancy word for "Canopy" that can make it more expensive while we are on the topic of marketing!

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Hey,

Well, a traditional 7 or 9 cell canopy has 7 or 9 cells. It's based on the way the canopy is loaded on the top skin. With crossbracing it loads the topskin of the canopy to make it think it has a lineset of a 21 cell canopy without having all the drag of a 21 cell lineset. So, it has a 7 cell lineset, but with the crossbracing the top skin is loaded like a 21 cell, on a 7 or 9 cell the ribs in between lines are not loaded, that's why we call them 7 or 9 not 14 or 18 cells. It's not a marketing thing, just brilliant engineering.

Later,
Isaiah

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But non-crossbraced devides cell into two !! so Tonto's question stands .... 7 cell should be 14 Cell and 9 cell should be 18



By that theory then crossbraced canopies would be 28 and 36 cell canopies.
----------------------------------------------
You're not as good as you think you are. Seriously.

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I thought it had to do with the bolt size of fabric,,old technology,,read it on here somewhere....



The width of a fabric bolr is why ParaFlite went to span construction on canopies like the DC-5 and the MT-1S. It allowed them to make the cells wider and make a 5 cell that had a higher aspect ratio.

Sparky
My idea of a fair fight is clubbing baby seals

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But non-crossbraced devides cell into two !! so Tonto's question stands .... 7 cell should be 14 Cell and 9 cell should be 18



By that theory then crossbraced canopies would be 28 and 36 cell canopies.



Ummmm, there is ONE :P:D:D

Never look down on someone, unless they are going down on you.

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But non-crossbraced devides cell into two !! so Tonto's question stands .... 7 cell should be 14 Cell and 9 cell should be 18



By that theory then crossbraced canopies would be 28 and 36 cell canopies.



Ummmm, there is ONE :P:D:D


And probably just the one, since according to that logic, the others would be 35- and 45-cell canopies.
What a wonderfully confusing thread...

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And just to muddy the water some more: I used to have an Aqutron canopy that was called a seven-cell, but five of the seven cells had two chambers, and two of the seven cells had three chambers. So it was a 7-cell 16-chamber parachute...

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> I used to have an Aqutron canopy that was called a seven-cell, but five of the seven cells had two chambers . ..

Yep. The old Strong tandem 11-cell canopies had two cells per cell for most of the cells, but 3 on the outer ones. So they would really be 24 cell canopies.

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Hey,

Look at the picture of that 7 cell 16 chamber thing....just the top skin. You can see 7 very distinct cells. In between the loaded ribs the top skin just domes up, the chambers aren't doing much other than pulling the bottom skin up with it, now look at the Velocity....in between the line attachments (on the top skin) it doesn't dome up, because the crossbracing is also loaded. so looking at just the top skin you see 21 very distinct cells.

Isaiah

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The old Strong tandem 11-cell canopies had two cells per cell for most of the cells, but 3 on the outer ones. So they would really be 24 cell canopies.



I f I remember correctly, the Set 400 is made that way, but I think two cells on each end are tri chambered.

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