Forums: Skydiving: Gear and Rigging:
Packing volume tolerances + / -

 


ScoopUK  (A 105948)

May 22, 2013, 12:22 PM
Post #1 of 16 (1426 views)
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Packing volume tolerances + / - Can't Post

Hi,

I'm turning to the community as I haven't yet got a response from my container manufacturer (pre-empting the smart arse stock reply). Hopefully they are busy building my gorgeous rig rather than answering stupid e-mails Wink

I've read many times that as a rough rule of thumb you can generally go up or down a size of canopy (assuming its a like for like type of canopy).

My container is sized for a specific canopy which I have already but I may buy another as I just fancy a new one and I've been offered a good deal which makes it more worthwhile.

The new canopy I'm looking at, depending on which packing volume figures you believe, may be larger in volume anything from 4-29 cu in. Is this a possible issue or no problemo? I don't really have an understanding of how much 29 cu in is in my head.

Ta very much


Quagmirian  (A 110392)

May 22, 2013, 12:29 PM
Post #2 of 16 (1399 views)
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Re: [ScoopUK] Packing volume tolerances + / - [In reply to] Can't Post

Twenty nine cubic inches is about the difference between a Sabre 190 and a Sabre 210, one size in other words. You can tell us what canopy and container combo you are looking at, and see if anyone else is using it, and with how much ease.




JerryBaumchen  (D 1543)

May 22, 2013, 3:08 PM
Post #4 of 16 (1271 views)
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Re: [ScoopUK] Packing volume tolerances + / - [In reply to] Can't Post

Hi Scoop,

Quote:
I don't really have an understanding of how much 29 cu in is in my head.

Few people do. Try using this formula: Sphere = (4/3) pi r^3

Do this: sphere = (4/3) pi r 3 = 29 cu inches

Now solve for r and then you will know what a ball that has a volume of 29 cu inches is. This should get you into some ballpark idea.

No, I am not going to do your homework for you.

Best of luck,

JerryBaumchen


Quagmirian  (A 110392)

May 22, 2013, 3:34 PM
Post #5 of 16 (1250 views)
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Re: [JerryBaumchen] Packing volume tolerances + / - [In reply to] Can't Post

A radius of about 1.9 inches sir. Anyway, a better solution to the problem is the imagine a cube with edges of length L and volume V. In this case that makes a cube with sides of about 3 inches.


JerryBaumchen  (D 1543)

May 22, 2013, 4:11 PM
Post #6 of 16 (1223 views)
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Re: [Quagmirian] Packing volume tolerances + / - [In reply to] Can't Post

Hi Quag,

Quote:
. . .sir . . .

Let's have none of that 'sir' stuff, OK. Tongue

Just after I posted that info I got to thinking and came up with a better idea.

1. Since I do not know, I will make an assumption that his main pack tray is 12 inches wide ( east to west ).
2. Since I also do not know, I will make an assumption that his main pack try is 6 inches long ( north to south ).

Take 12 x 6 = 72

ETA to change this: Now take this 72 cu inches and divide by his 29 cu inches and you get 0.4 inches thick. So a canopy of 30 cu inches greater in volume ( for many rigs ) would be about 3/8 inches thick.

Something to do on a rainy afternoon, ETA: If I was paying attention. Pirate

JerryBaumchen


(This post was edited by JerryBaumchen on May 22, 2013, 5:12 PM)


DBCOOPER  (D 24112)

May 22, 2013, 4:37 PM
Post #7 of 16 (1206 views)
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Re: [ScoopUK] Packing volume tolerances + / - [In reply to] Can't Post

ScoopUK wrote:

I've read many times that as a rough rule of thumb you can generally go up or down a size of canopy (assuming its a like for like type of canopy).

I think thats an old rule of thumb. I think todays manufactures make the rig for the canopies you tell them your going to put in it. Thats been my experience with Sun Path and UPT.




JerryBaumchen  (D 1543)

May 22, 2013, 10:36 PM
Post #9 of 16 (1139 views)
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Re: [JerryBaumchen] Packing volume tolerances + / - [In reply to] Can't Post

Hi out there,

Wow, I just keep making this worse.

Quote:
Now take this 72 cu inches and divide by his 29 cu inches and you get 0.4 inches thick.

Wrong, wrong & wrong again.

Now take this 29 cu inches and divide by his 72 cu inches and you get 0.4 inches thick.

That's much better. Pirate

Maybe that is why I was never a 4.0 student.

Wink

JerryBaumchen


theonlyski  (D License)

May 23, 2013, 4:29 AM
Post #10 of 16 (1049 views)
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Re: [JerryBaumchen] Packing volume tolerances + / - [In reply to] Can't Post

JerryBaumchen wrote:
Maybe that is why I was never a 4.0 student.

I couldn't even spell 4.0!


sundevil777  (D License)

May 23, 2013, 4:53 AM
Post #11 of 16 (1037 views)
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Re: [JerryBaumchen] Packing volume tolerances + / - [In reply to] Can't Post

The 72 was square inches, not cubic. Laugh

If you're going to make fun of yourself, then expect us to pile on...


JerryBaumchen  (D 1543)

May 23, 2013, 8:30 AM
Post #12 of 16 (984 views)
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Re: [sundevil777] Packing volume tolerances + / - [In reply to] Can't Post

Hi Cliff,

Quote:
If you're going to make fun of yourself, then expect us to pile on...

Have at it; I deserve it for the pathetic exercise.

Unsure

JerryBaumchen

PS) Isn't there some rule/old adage about do not do things when you are tired? I just might learn that one day.








JerryBaumchen  (D 1543)

May 23, 2013, 2:04 PM
Post #16 of 16 (857 views)
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Re: [Festus] Packing volume tolerances + / - [In reply to] Can't Post

Hi Festus,

Quote:
I think you divided at the end when you should have multiplied.

A long time ago I learned that I cannot walk on water.

Tongue

What I should have done, is stayed completely away in the first place. All I continued to do is make myself look like a mathmatical idiot. Crazy

There are those days when one wishes he/she should have simply stayed in bed.

JerryBaumchen

PS) And with most packtrays larger than 12 x 6, it is not even as much as 0.4 inches, which is about 3/8".

Now, did I get that right? Wink



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