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PC for Mirage/Cobalt Combo?

 

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JYorkster  (D 23658)

Dec 19, 2003, 4:47 AM
Post #1 of 72 (1933 views)
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PC for Mirage/Cobalt Combo? Can't Post

Ok, here's the deal...

My wife just got a new Mirage G4 and a Cobalt canopy. Mirage sent a 28" F-111 pilot chute and says that's the correct PC for that container. Cobalt recommends a 22-24" zero-p PC for the canopy.

We put it together with a 24" z-p PC, but she hasn't had a chance to jump it yet.

Anyone else out there have this container/canopy combination? If so, what type of PC do you have? Thoughts?

Thanks for the info,
Rock


RTB  (D 582)

Dec 19, 2003, 4:53 AM
Post #2 of 72 (1875 views)
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Re: [JYorkster] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

 
I have that combination and made my original Mirage PC smaller. It is now about 23". I would not recommend this however, since the original F-111 PC does not seam to have that much drag. If you change to a ZP PC then I think a smaller one would be fine.
My PC does work for me, but in a hop and pop or balloon jump or so it would be less that ideal.

//r


darkvapor

Dec 19, 2003, 4:59 AM
Post #3 of 72 (1867 views)
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Re: [JYorkster] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

Just keep in mind that all pilot chutes are not created equal. With smaller pilot chutes, the margin for manufacturing and design errors goes down. Refer to the following thread for more details, and figuring out if your pilot chute is designed well:

http://www.dropzone.com/...t_reply;so=ASC;mh=35

To answer your question more directly, I've had a Cobalt 170 in a Wings W-13 (proper size for a 170), using a Jim Cazer 24" pilot chute, and I found that terminal deployments were excellent and no hesitation. But subterminal openings were a bit scarier, often with some scary delays between throwing the PC and getting a canopy over my head.


grega  (D 100020)

Dec 19, 2003, 5:07 AM
Post #4 of 72 (1860 views)
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Re: [JYorkster] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

I have the exact same configuration. Though i use mirages 28" f-111 PC. and the openings are very soft, up to 7 seconds - around 1000 feet sometimes.

I think she should be fine with this setup. but if you have the main canopy packed in tight, i'd ask mirage what do they think about 24" zp for opening.


Premier Tonto  (D 515)
Moderator
Dec 19, 2003, 5:09 AM
Post #5 of 72 (1857 views)
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Re: [JYorkster] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

I'm a fan of bigger F-111 pilot chutes, and replacing them more often (Every 250 jumps, or 9 months for me) than smaller ZP which last longer but give me harder terminal openings.

t


psw097  (D License)

Dec 19, 2003, 5:41 AM
Post #6 of 72 (1849 views)
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Re: [JYorkster] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

All summer while doing 4-way I was using a 22" PC without issue. After nationals I went back to video/freefly about the same time the weather started getting cooler. The slower deployment speeds without the super slick RW suit and higher pack volume was making for some sweet PC in-tow fun.

Got some nice video of fighting with a PC in-tow while someone, that decided not to track, dumped under me on a video jump.

Well, I rotated all my PCs after that putting the 24" on the 94 and 27" on the 105. Much better.


AggieDave  (D License)

Dec 19, 2003, 5:48 AM
Post #7 of 72 (1845 views)
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Re: [JYorkster] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

Quote:
Mirage sent a 28" F-111 pilot chute and says that's the correct PC for that container.

There's your answer. A PC is apart of your container system, changing it to a smaller PC may produce a PC in tow situation. Call up Mirage and talk to them, tell them what Atair wants you to have and see if they say its ok. They might, then they might not. In the end its up to you.


diablopilot  (D License)

Dec 19, 2003, 7:01 AM
Post #8 of 72 (1820 views)
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Re: [JYorkster] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

Ditto what AD said.

Go with the proper P/C for your container. The Cobalt/Atair recomendations are a bunch of hooey dreamed up to fix a "problem" canopy.

P/C's are sold with the container they are designed for. I have plenty of jumps on my G4 with it's original P/C and it works well.


(This post was edited by diablopilot on Dec 19, 2003, 7:03 AM)


Hooknswoop  (D License)

Dec 19, 2003, 7:05 AM
Post #9 of 72 (1816 views)
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Re: [diablopilot] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

Ditto what Diablopilot said. A collapsible PC should have zero effect on how a canopy opens. It collaspes as the canopy comes out of the bag.

Derek


HeatherB  (B License)

Dec 19, 2003, 7:21 AM
Post #10 of 72 (1810 views)
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Re: [JYorkster] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

I'll say this...

When I was at Wings, we had a customer who REALLY wanted the tiny PC that Atair recommended, to go with his new Wings. I refused to order him one, told him the combination would result in at least PC hesitation. He got pissed off and went and got a 22" from another manufacturer and voila - PC in tow on his first jump.

He called to say "Sorry, I should have listened..."

Moral of the story - go with the rig manufacturer's recommendation first.

That's my not-so-humble opinion anyhow. Wink


Ron

Dec 19, 2003, 8:15 AM
Post #11 of 72 (1786 views)
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Re: [HeatherB] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

In reply to:
Moral of the story - go with the rig manufacturer's recommendation first.

A pilot chute is part of the container....Not the parachute.

I would go with what the manufactorer recomends...It is the set up that they tested the system with....And changes to that setup, and you become a new test jumper.

This is my big problem with Cobalts....I put a few jumps on a 105, and while it flew great, it opened hard as hell. When I talked to the rep about it...He told me I needed a new PC....I asked him why since it worked great with my Stiletto, and was part of the container, not the parachute....He told me that it would be fine to jump a smaller PC...And I gave him the canopy back.

Any canopy that requires different components than other same size/type of canopy...Has issues...

A different PC or bigger slider is lame fix to a design problem.


ChasingBlueSky  (D License)

Dec 19, 2003, 8:31 AM
Post #12 of 72 (1773 views)
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Re: [Ron] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

In reply to:
Any canopy that requires different components than other same size/type of canopy...Has issues...

A different PC or bigger slider is lame fix to a design problem.

Exactly! If the brakes on your car failed, would you blame the tires?

The PC is there to pull the pin and extract the bag and begin the deployment. A canopy that is designed correctly will be able to handle the relative wind at typical deployment speeds with the PC the rig manufacture recommends. If it can't, then take Ron's lead and get rid of that canopy.

From the way it sounds, AtAir has spent more time figuring how a PC can effect the opening sequence and not given any consideration to how much pull force will be required to get the pin out in all situations (sub terminal, terminal, bulky pack jobs, etc). You won't have to worry about that hard opening or sweetly staged opening because the pin will probably never leave the loop.


jrcrackers  (D 26874)

Dec 19, 2003, 8:34 AM
Post #13 of 72 (1770 views)
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Re: [Hooknswoop] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

In reply to:
A collapsible PC should have zero effect on how a canopy opens. It collaspes as the canopy comes out of the bag.
I disagree, The speed at which the bag gets to that point is controled by the pilot chute. Depending on material and size as well as length of bridle can effect how the pack job gets presented to the air.
I do agree that the pilot chute should match the container. I recieve questions about this combination frequently at VSE & my answer is always the same.


rigging65  (D 21921)

Dec 19, 2003, 8:51 AM
Post #14 of 72 (1752 views)
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Re: [jrcrackers] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

Hmmmm...I disagree. There is certainly more snatch force generated by a bigger P/C, or a longer bridle, but does this really have anything to do with how the canopy opens? The bag gets to the end of the lines faster, but does it change the opening?

I think we can agree that your bag certainly reaches line stretch faster if you don't stow your lines, but that doesn't change the opening characteristics...so why would the bag getting to the end of the lines faster because of the pilot chute be any different?


DBCOOPER  (D 24112)

Dec 19, 2003, 9:08 AM
Post #15 of 72 (1745 views)
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Re: [JYorkster] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

I recently had a G3 and used a 24" zp pilot chute with a Cobalt 150 and had zero issues in 250 jumps.


jrcrackers  (D 26874)

Dec 19, 2003, 9:43 AM
Post #16 of 72 (1731 views)
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Re: [rigging65] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

I think it can, in some situations. If the pilot chute has slowed the bag down too much, while the jumper is still mvoing at the same speed, the canopy will get a stronger shock and disrupt or spread apart the pack job causing the canopy to inflate faster or harder.
Fot the most part I don't think it plays a huge roll in opening but to say a pilot chute has nothing to do with opening is not true. Everthing must work together to produce a good opening.


Premier PhreeZone  (D License)
Moderator
Dec 19, 2003, 9:58 AM
Post #17 of 72 (1724 views)
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Re: [DBCOOPER] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

I had a Javelin with a 30 inch F111 and a Cobalt 150 with no issues either... PC size should'nt play a factor in the openings of the canopy. And too small of a PC does cause issues.


Hooknswoop  (D License)

Dec 19, 2003, 12:10 PM
Post #18 of 72 (1694 views)
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Re: [jrcrackers] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

Quote:
I disagree, The speed at which the bag gets to that point is controled by the pilot chute. Depending on material and size as well as length of bridle can effect how the pack job gets presented to the air.
I do agree that the pilot chute should match the container. I recieve questions about this combination frequently at VSE & my answer is always the same.

During the opening sequence, the bag slows down. The larger the PC, the more it slows down. As the canopy comes out of the bag, the PC collapses and has no further effect on the opening.

If the bag is de-accelerated 10 mph or 20 mph shouldnt affect the opening. Micro lines, Vectran, and HMA dont stretch, so the canopy is accelerated tot he jumpers speed very quickly as the bag is coming off the canopy, before it has a chance to do anything. The, now at the same speed as the jumper, the canopy begins to open. The PC can affect the time it takes the canopy to get to line stretch, but doesnt cause hard openings.

Id be willing to bet I can make a canopy open hard with a small PC and then make the same canopy open soft with a large PC.

Derek


nicknitro71  (D 26704)

Dec 19, 2003, 12:33 PM
Post #19 of 72 (1692 views)
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Re: [Hooknswoop] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

I'm with Derek on this 100%. Unless somebody shows me real data proving a bigger pilot chute gives harder openings I just dont buy it. At my DZ we all jump at least 28" regardless the size of the chute. A 28" solved several chronic line twists on few Velos, and we do a lot of sub H&Ps too. When I ordered my Wings I requested a 28 for my Viper 105. The DZO jumps a Xaos 78 guess with what PC, yes a 28. IMO smaller than 28 does not make any sense at all. At some point I was jumping a Hornet 150 with a 24. It opened OK at terminal but few times I got line twists at sub and PC hesitation.

Here is my break down:

150 or smaller 28.

170 or bigger 32.


rigging65  (D 21921)

Dec 19, 2003, 1:47 PM
Post #20 of 72 (1677 views)
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Re: [jrcrackers] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

Quote:
If the pilot chute has slowed the bag down too much, while the jumper is still mvoing at the same speed, the canopy will get a stronger shock and disrupt or spread apart the pack job causing the canopy to inflate faster or harder.

We'll have to agree to disagree on this one, 'cause I don't buy it. The slider is so much larger a component when it comes to hard openings that I don't think even a 10-15 mpfh difference in the bag's speed is going to make a damn bit of difference.

If I arch my ass off during a deployment, I'm probably doing about 135. If I get huge, then pitch, I'm probably doing about 115. My canopy opens the same regardless. If the change in decelerative effect was 50-60 mph, then I might buy it, but the differences just aren't enough, IMO.

I agree that everything must work as a system, but I'd say the P/Cs job in that system is simply to get the bag to line stretch. Canopy design, trim and Slider placement and design/size do the rest.


imdskydiver  (C 2457)

Dec 19, 2003, 1:54 PM
Post #21 of 72 (1678 views)
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Re: [rigging65] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

Quote:
Bill's reply:

Your pilot chute is "unsafe" if it doesn't deploy your main correctly. What is "correctly"? You want your pilot chute to open your container and the pull your bag away from your container quickly, but not too quickly. If your pilot chute accelerates your bag away from you too slowly you have the potential for line twists because of the extra time your unsymmetrical deployment bag is exposed to the slipstream, or a bag lock caused by your suspension lines actually "blowing up" above your bag and entangling with it. Not to mention taking more altitude than necessary to deploy. If your pilot chute accelerates your bag too quickly, you have the potential for inertial line dump, high snatch force (when the canopy hits the end of the lines and is decelerated back to your speed), slider rebound (where the slider bounces off the slider stops and your canopy starts its opening sequence with the slider a few inches down the lines. OUCH), and a generally disorganized opening, increasing your chance of malfunction.


rigging65  (D 21921)

Dec 19, 2003, 2:06 PM
Post #22 of 72 (1670 views)
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Re: [imdskydiver] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

Quote:
What is "correctly"? You want your pilot chute to open your container and the pull your bag away from your container quickly, but not too quickly.

Great! So, what constitutes too quickly? What size P/C would that be? Like I said, if you're "large" P/C were giving you 50-60 mph more deceleration than your "small" P/C, I'd say there's a problem...but they're not. So, again, define the size(s) that causes these problem....I'm not sure that you can, nor do I think any definition would be valid at all times because there isn't enough variance between them!

So, we're back to: Pretty much any P/C on the sport market (not BASE) is going to result in about the same openings for a given canopy.

Sliders and line trim, folks, sliders and line trim are where its at...


twnsnd  (D 25389)

Dec 19, 2003, 2:22 PM
Post #23 of 72 (1666 views)
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Re: [rigging65] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

Hee Hee Hee...You said snatch.Laugh But seriously as far as this thread goes, If the canopy is still new, just get something else. Just my 2/100 of a dollar.


TALONSKY  (D License)

Dec 19, 2003, 3:01 PM
Post #24 of 72 (1652 views)
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Re: [twnsnd] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

I have always heard the best way to get a Cobalt to open nice is to get rid of it and buy a Crossfire 2. Unless you want a lesson on how many ways it is not the canopies fault it open's hard.Wink
Kirk


imdskydiver  (C 2457)

Dec 19, 2003, 3:32 PM
Post #25 of 72 (1642 views)
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Re: [rigging65] PC for Mirage/Cobalt Combo? [In reply to] Can't Post

Quote:
What is "correctly"? You want your pilot chute to open your container and the pull your bag away from your container quickly, but not too quickly.
From Bill Booth :
Quote:
The ideal separation velocity, that is the speed which the canopy is traveling away from you at line stretch, is 50 feet per second. An acceptable range is 30 to 70 FPS. If a pilot chute causes separation velocity outside that range, I do not considerate it "safe". How can you tell what your separation velocity is? You can look at a video of one of your deployments and count video frames at 30 per second. An acceptable time from container opening to line stretch is 0.45 to 0.75 seconds, or about 13 to 22 frames. Any faster or slower and you are "asking for it"

For the record i have a Mirage and a Cobalt 120 and use a 28" pilot chute without any problems , I tried a 22"Cazer P/C but was not impressed with it , I felt it was too small and slippery to be put into a spandex poach that was built for a 28" P/C .


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