Forums: Skydiving: Gear and Rigging:
Pilot Chute Sizing (oversized)

 


Mac  (C 101464)

Dec 6, 2012, 12:33 AM
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Pilot Chute Sizing (oversized) Can't Post

What issues with standard skydiving set up (bungee stowed D-Bag, flat and stable deployment) can an oversized PC give you?


piisfish

Dec 6, 2012, 12:34 AM
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Re: [Mac] Pilot Chute Sizing (oversized) [In reply to] Can't Post

how oversized ?


skydiverek  (C 952)

Dec 6, 2012, 12:48 AM
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Re: [Mac] Pilot Chute Sizing (oversized) [In reply to] Can't Post

PC section:

http://www.performancedesigns.com/docs/hrdopn.pdf


Mac  (C 101464)

Dec 6, 2012, 12:56 AM
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Re: [piisfish] Pilot Chute Sizing (oversized) [In reply to] Can't Post

I was speaking just in general terms really. Bascially I ask, as I am finding more people getting hung up with PC sizing for Wingsuiting.

As an example, I maintain my standard PC (28") for wingsuit as I feel the drag force at terminal (c.160lbs) is sufficient, whereas upsizing to say a 32" with force of c.210lbs is excessive. Even with non-terminal speeds, say 6sec delay speed, the 28" creates >100lbs, and thus will be sufficient (in skydiving). I dont really see an issue with a few inches more for Wingsuiting (if that is what makes you feel happier), but should you then take it out on a "normal" skydive, what issues may you have then.

I have heard of people looking at 34" PC for Wingsuit, and to me that is way excessive (>230lbs at terminal), however I dont really understand what issues this increased PC size will give within the skydiving environment, my small brain cant work out what potential issues there are, so thought I would ask. Am I focusing on the wrong thing here?

I understand not just drag, but snatch force would also be a consideration, with a greater snatch created by the "grab" of a bigger PC, and maybe you can educate me in that, even so, the smaller PC is still sufficent for WS and general terms.

Maybe the advantages of a bigger PC for wingsuit arent discounted by the disadvantages of a bigger PC in normal skydiving deployments, and as such, if sacrificing a chicken makes you feel safer, then do it.

I hope the above is clearer than it sounds to me re-reading! Smile


Mac  (C 101464)

Dec 6, 2012, 12:57 AM
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Re: [skydiverek] Pilot Chute Sizing (oversized) [In reply to] Can't Post

Nice one, interesting.

Cheers


Mac  (C 101464)

Dec 7, 2012, 8:56 AM
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Re: [Mac] Pilot Chute Sizing (oversized) [In reply to] Can't Post

Ignore my figures on PC drag, I have since referenced another source of calculation, and it would seem my original source calcs maybe incorrect.

Thanks to the chap who pulled me up on those figures to look further into it.....

Theory is still the same, the figures maybe not....


riggerrob  (D 14840)

Dec 10, 2012, 10:26 AM
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Re: [Mac] Pilot Chute Sizing (oversized) [In reply to] Can't Post

In reply to:
What issues with standard skydiving set up (bungee stowed D-Bag, flat and stable deployment) can an oversized PC give you?

....................................................................................

Worst case scenario: your pilot-chute is so vastly over-size that it jerks your d-bag off your back so violently that it leaves all the lines laying in the pack tray (aka. bag strip) ... then the slider only lifts half as fast as the canopy and gets messed up with the dis-organized suspension lines (aka. "spaghetti mess"). ... tension knots, line burns, broken lines, torn stabilizers, etc.
You will NOT enjoy that opening.

When you finally get to line-stretch, the massive pilot-chute tears the bridle attachment off the top of your canopy, taking a large chunk of top-skin with it! The resultant "soft" center cell folds up when you flare!
You will NOT enjoy that landing!

Seriously, if you keep your pilot-chute between 26 inches and 36 inches diameter, your canopy will open.


SEREJumper  (D 29555)

Dec 10, 2012, 12:53 PM
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Re: [Mac] Pilot Chute Sizing (oversized) [In reply to] Can't Post

On a side note, a lot of people have switched to 9ft bridles for wingsuiting and the increased length helps the PC get out of the burble. Then there are others that just stick with the standard length and it seems to work out as well.


fasted3  (D 30104)

Dec 10, 2012, 5:11 PM
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Re: [SEREJumper] Pilot Chute Sizing (oversized) [In reply to] Can't Post

In reply to:
On a side note, a lot of people have switched to 9ft bridles for wingsuiting and the increased length helps the PC get out of the burble. Then there are others that just stick with the standard length and it seems to work out as well.

Yes, most people have switched to 9' bridles and it works well. A few have not and claim it works well for them too, but others have tried it and had problems with PCIT and deployment delays. As I am one that had this experience, I'd recommend the longer bridle for wingsuiting, especially with a bigger suit.
My PC is 27" F111 and it deploys my Safire2 190 just fine.


Mac  (C 101464)

Dec 10, 2012, 11:46 PM
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Re: [fasted3] Pilot Chute Sizing (oversized) [In reply to] Can't Post

The bridle is another discussion, I have only moved to 9' bridle (pin to PC attachment) with the move to bigger suits, the standard bridle working fine up to the point of the larger suits and burble creation from these suits.

The point of my post, is I am of the mindset that the standard PC (I have a 28" F1-11) works fine with WS, requiring only a longer bridle for larger suits. I was just wanting to understand the issues in upsizing (as a lot of people do), as I dont personally believe it to be necessary, and feel some people go for a bit of overkill in their choices without thought of the disadvantages.

Thanks all for responses.



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