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Argus fire and Racer Reserve PC in tow

 

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divnswoop  (D 18276)

Dec 12, 2012, 6:20 PM
Post #1 of 26 (4516 views)
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Argus fire and Racer Reserve PC in tow Can't Post

Just heard about an incident in Florida where a jumper wearing a racer deployed the main low and had an Argus fire. The main was a Sabre 2 loaded at 1+ to 1 and they flew the main to the ground. The reserve PC stayed in tow and never deployed the reserve. Upon landing and taking off the gear the free/speed bag fell out.

Argus fire too low for reserve extraction?
Argus not completely cut the loop?
Reserve PC not create 18 pounds of pressure to pull the bag off?
Anybody know what happened?


pchapman  (D 1014)

Dec 12, 2012, 6:40 PM
Post #2 of 26 (4462 views)
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Re: [divnswoop] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

Oh man, Argus's AND Racers all in the same thread. This is gonna be fun.

One does wonder about the timing of the Argus fire relative to the jumper's speed through the air.


BigMark  (D 17505)

Dec 12, 2012, 6:47 PM
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Re: [pchapman] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

What dropzone?


pchapman  (D 1014)

Dec 12, 2012, 7:25 PM
Post #4 of 26 (4394 views)
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Re: [pchapman] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

Hmm, doing the calculations, it does look like it takes some speed to get much drag out of a reserve pilot chute.

We know that in practice, a reserve pilot chute won't always extract the bag when someone is flying at lower speeds. The calculations are just there to compare to theory.

Hope I didn't do the numbers wrong, but if one does the standard drag equation of drag = half * rho * V-squared * reference area * Cd, I get 18 lbs of pull force only at 41.5 mph, if the reference diameter for a Racer reserve pilot chute is 30". That's about what I measure for one as the finished, constructed diameter. (If somehow one used a more generous 36", the number would be 34.5 mph). The drag coefficient is taken to be Jumpshack's own reported value of 0.83.

For a lighter, maybe more practical 10 lb extraction force, 31 mph are needed.

If one is considering a scenario where other rigs' reserve pilot chutes are no more efficient, and are no larger than 36", then the above 34.5 mph value will also apply as a minimum speed to achieve 18 lbs of force.

Now I don't think that the Racer freebag would normally take 18 lbs of extraction force, but that's a number that was in a JumpShack document about what they consider to be maximum acceptable bag extraction forces for any rig at most angles, and was mentioned by the original poster.
(Reference: http://www.dropzone.com/...um.cgi?post=3922046;

Still it is a surprise that the reserve didn't get pulled out while the jumper was still at higher speed during the main canopy deployment. The minimal info presented so far doesn't suggest that there was any factor causing a hard extraction of the bag from the rig.


spage  (C License)

Dec 12, 2012, 8:11 PM
Post #5 of 26 (4361 views)
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Re: [divnswoop] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

I know nothing of the incident posted, but have witnessed the exact same thing happen to a Cypres equipped Wings rig.

Cypres fired during snivel, and the jumper was under a fully open canopy with a trailing reserve PC. The free bag stayed put until after landing.


riggerrob  (D 14840)

Dec 12, 2012, 8:20 PM
Post #6 of 26 (4348 views)
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Re: [spage] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

I have seen the same scenario with an FXC 12000 and a Vector reserve pilot-chute.
Since the main was partly inflated by the time the FXC 12000 fired, the reserve pilot-chute never generated enough drag to deploy he main canopy.

That is what containers are supposed to do! ... some reserve containers even include staging loops to ensure that the reserve pilot-chute is pulling more than "X" pounds before it can lift the reserve deployment bag off your back.


JohnSherman  (D 2105)

Dec 12, 2012, 11:55 PM
Post #7 of 26 (4250 views)
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Re: [pchapman] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

Peter,
A couple of things: At 2000 ft I calculate 52FPS or 35.5MPH which generates 3 psf. The standard Racer Reserve PC is 36 inches diameter or 7.06 Sq. Ft. (The SRP is 30 inches) With a Cd of .83 we calculate 3*7.06*.83= 17.57 pounds Rounded off to 18 pounds. We agree on the numbers but you just got one of my small ones (SRP) which is not used on anything but smaller canopies.
A Racer free bag will not take 18 pounds to extract. I provided that number as an absolute ceiling for any rig because I dont know of any pilot chutes which will handle it. It must be the absolute acceptable maximum for any rig when we test it on the ground.
We do limit our extraction at 17 pounds but we know it is just the weight of the canopy and bag that is required and I put the big number out there because I knew our PC could handle it even on tandem reserves.
I can envision this event happening if the reserve fired just as the main blossomed. The PC takes 1 second to get to the end of the bridle at 3 Pounds per Sq. Ft. (Q). But now the canopy doesnt fly at 35MPH. It maybe flies at 15 to 20 MPH. At 23 MPH at 2000 ft. the Q is only 1.28 pound per sq. ft. 5.86 Effective Sq. Ft. There is only 7.5 pounds of drag. Not enough to pull the bag out horizontally when aligned vertically.
It comes out only when it is supposed to. I like that. I will find out more tomorrow.
John


Premier skydiverek  (C 41769)

Dec 13, 2012, 4:42 AM
Post #8 of 26 (4156 views)
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Re: [spage] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

In reply to:
I know nothing of the incident posted, but have witnessed the exact same thing happen to a Cypres equipped Wings rig.

Cypres fired during snivel, and the jumper was under a fully open canopy with a trailing reserve PC. The free bag stayed put until after landing.

I heard that this is a desirable scenario on rigs. Use some extraction friction, so that the two-out is avoided, and you just keep reserve PC-in-tow, while flying the main canopy. What is wrong with that (assuming that a slightly higher speed would deploy the reserve, like after the cutaway)?


(This post was edited by skydiverek on Dec 13, 2012, 4:42 AM)


spage  (C License)

Dec 13, 2012, 8:07 AM
Post #9 of 26 (4084 views)
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Re: [skydiverek] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

In reply to:
I heard that this is a desirable scenario on rigs. Use some extraction friction, so that the two-out is avoided, and you just keep reserve PC-in-tow, while flying the main canopy. What is wrong with that (assuming that a slightly higher speed would deploy the reserve, like after the cutaway)?


We were glad it didn't come out! It was certainly desirable in this case.

The Argus & Racer were both mentioned, so I was just pointing out that I've seen other brands behave the same way.


GLIDEANGLE  (D 30292)

Dec 13, 2012, 9:28 AM
Post #10 of 26 (4041 views)
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Re: [divnswoop] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

I once saw a similar outcome on a Student Vector (w/ Skyhook) and Student Cypres. The jumper was deliberately spiraling the main maximally with toggle for a long time and the Cypres fired. The jumper aborted the spiral low and landed OK with the freebag still in the container.


TMPattersonJr  (D 30299)

Dec 13, 2012, 10:11 AM
Post #11 of 26 (4003 views)
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Re: [divnswoop] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

Answers in the quote below. Wink

In reply to:
Just heard about an incident in Florida where a jumper wearing a racer deployed the main low and had an Argus fire. The main was a Sabre 2 loaded at 1+ to 1 Incorrect. The main was a FireBolt 146, loaded at right at 1-1 with the jumper weighing 130 and the rig w/ canopies weighs 20 lbs. in the plastic tote that it's sitting in waiting to repacked and they flew the main to the ground. The reserve PC stayed in tow and never deployed the reserve. Upon landing and taking off the gear the free/speed bag fell out.

Argus fire too low for reserve extraction? Possibly, I was not there to witness the event first hand, and can't send the unit to be read. There is the possibility and yes this is speculation but she could have been falling fast enough under a snivelling canopy for the unit to fire, but slow enough that after reserve bridle extension under a lightly loaded main not be moving fast enough for the P/C to extract the bag.
Argus not completely cut the loop?Argus did its job and I have the pieces of the loop to prove it.
Reserve PC not create 18 pounds of pressure to pull the bag off?See John's post above.
Anybody know what happened?I talked to the DZO and the jumper afterwards and got both accounts, it's been about a month but I do not recall them exactly, but low pull resulting in AAD fire sometime around or after main deployment initiation. Unit was set on pro mode, and reserve had been packed less than two weeks prior. Everthing else is left to science and John has already addressed that. And for the record it is not our SRP reserve P/C it was the full size with a 6" cap.




divnswoop  (D 18276)

Dec 13, 2012, 8:41 PM
Post #13 of 26 (3822 views)
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Re: [] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

Great to hear everything worked as it should per the people that investigated it....
It is a Shame we can't get any info from the AAD manufacture. It may have cut the loop...but where?


(This post was edited by divnswoop on Dec 13, 2012, 8:43 PM)


divnswoop  (D 18276)

Dec 13, 2012, 8:48 PM
Post #14 of 26 (3815 views)
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Re: Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

what is the forward speed of a fire bolt 146 loaded 1-1?


davelepka  (D 21448)

Dec 13, 2012, 9:03 PM
Post #15 of 26 (3811 views)
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Re: [skydiverek] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

Quote:
I heard that this is a desirable scenario on rigs. Use some extraction friction, so that the two-out is avoided, and you just keep reserve PC-in-tow, while flying the main canopy. What is wrong with that (assuming that a slightly higher speed would deploy the reserve, like after the cutaway)?

What's wrong with that thought is that if it requires just a little more force than you expect, the deployment is delayed and valuable altitude is wasted trailing the PC while the jumper gets up to speed.

How do you account for a larger reserve being used? How do you account for a pack job where the bulk is distributed differently? How about when a larger jumper wears an undersized harness? Or a smaller jumper on a larger harness? All of the above will effect the extraction force, and because of that, you can't attempt to 'tune' is to the PC trails under a good canopy and functions at a slightly higher airspeed.

The reserve container is either open, or closed. There should never be any 'in between'.


pchapman  (D 1014)

Dec 14, 2012, 6:04 AM
Post #16 of 26 (3705 views)
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Re: [davelepka] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

In reply to:
How do you account for a larger reserve being used?

99%of your posts are great but I'll have to comment here:

I'm not sure what you are criticizing in this case. Most of the rigs in the whole industry?

Racers have two different pilot chute sizes available, which is a rarity. Everyone else (?) has the same PC whether it is for a 99 reserve or student gear or a tandem.

In reply to:
The reserve container is either open, or closed. There should never be any 'in between'.

I thought there should be. We call it "staging" as you know. We had rigs with staging loops in the early 80s but everyone went to container friction to stage instead. Except for UPT who went back to an optional staging loop not because they wanted to for all rigs, but because the Skyhook, for all its good, adds a lot of complexity to a rig's function. (They added complexity to deal with complexity...)

So yes indeed there are a million variables and we haven't solved how to have every rig extract the bag at exactly the same speed (based on pilot chute pull force vs. bag mass vs. container friction) in every desired direction.

I thought we mostly still accept that at some low speed, it is better to have a pilot chute trail and not extract the bag, rather than have the bag just dump & tumble out.

Heck, one area of concern among skydivers is rigs that encapsulate the reserve bag possibly too tightly, and it seems like Racers are some of the least stiff and constricting ones on the market.


irishrigger  (D 297)

Dec 14, 2012, 11:18 AM
Post #17 of 26 (3634 views)
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Re: [divnswoop] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

 
It may have cut the loop...but where?

since the Reserve pilot chute was trailing it seems to me that the AAD that was in the rig did its job and cut the loop cleanly as it was supposed to! Tongue
the only thing one might learn from the AAD is the data that it recorderd as to height and speed. Is that what you are refering too with the above question?


JohnSherman  (D 2105)

Dec 14, 2012, 1:58 PM
Post #18 of 26 (3576 views)
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Re: [divnswoop] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

Quote:
what is the forward speed of a fire bolt 146 loaded 1-1?
I don't know but I have a digital recording anamometer with altimeter which record against a time line and I have a Firebolt 146.
If you know someone with the correct weight and available time and ability I'll make it available and pay for the jump.
I do have data on some size weight combos and am attaching the data from a 200 loaded at 1.05 to 1.
I would expect from the information found in this data that a 146 would perform about the same. This seems to be in the neighborhood of 15 to 20 FPS or 10 to 13 MPH.
Attachments: P_Curve_Data_for_Firebolt_200_189lbs.jpg (234 KB)


TrojanHorse

Dec 16, 2012, 3:10 AM
Post #19 of 26 (3170 views)
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Re: [divnswoop] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

Quote:
It is a Shame we can't get any info from the AAD manufacture. It may have cut the loop...but where?

Aviacom/ Argus has still spare cutters in stock. So far no request for a replacement has been received. By my knowledge (I have to check with Karel) is this thread the first we became aware of this activation. If we get the unit, or send to someone who can do a download (for example Chuting Star) we can provide some more info. This in combination with what John suggested will shine some more light upon what might have happened. Now we are all guessing it seems.

I read that the PC was in tow. This implicates it has been released IE the loop was cut or the reserve ripcord pulled. Further I read I have the pieces of the loop to prove it

Season greetings to all,
William


JohnSherman  (D 2105)

Dec 16, 2012, 10:21 AM
Post #20 of 26 (2993 views)
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Re: [divnswoop] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

Quote:
It is a Shame we can't get any info from the AAD manufacture. It may have cut the loop...but where?

Read the post above yours from TMPatterson it says:
"Argus not completely cut the loop?
Argus did its job and I have the pieces of the loop to prove it."


divnswoop  (D 18276)

Dec 16, 2012, 4:14 PM
Post #21 of 26 (2848 views)
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Re: [JohnSherman] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

Where....as in what altitude? Do you plan on sending the unit in to get the details?


mircan  (D 32291)

Dec 17, 2012, 4:42 AM
Post #22 of 26 (2644 views)
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Re: [TrojanHorse] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

Were you contacted regarding this incident LINK? (*sorry It is on FB, I got the link that way)
They state that "argus fires reserve canopy after main was opened for 30 sconds".
Any more info on that?


TMPattersonJr  (D 30299)

Dec 17, 2012, 5:24 AM
Post #23 of 26 (2614 views)
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Re: [divnswoop] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

Yes, I have sent an e-mail to William and am awaiting his reply. Smile


pchapman  (D 1014)

Dec 17, 2012, 7:38 AM
Post #24 of 26 (2528 views)
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Re: [mircan] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

In reply to:
Were you contacted regarding this incident LINK? (*sorry It is on FB, I got the link that way)
They state that "argus fires reserve canopy after main was opened for 30 sconds".
Any more info on that?

Just to be clear for everyone, that is a DIFFERENT incident, so we have two different events being discussed here.

For this "INCIDENT #2":

The facebook video of a jump at Skydive Miami shows a complete two out, with the reserve rising up behind and visible on camera only 40 seconds after opening. But although the jumper's initial thought was that the Argus fired 30 seconds after opening, the video alone can't prove that version of events -- it is possible to have the reserve PC in tow a while and not noticed, until it eventually extracted the bag.

The jumper did see 3500' or so on his alti shortly before his pull, and the timing of the rest of the video doesn't suggest any altimeter issue.

So it wasn't a low pull. Canopy is open at around 1:10 on the video, reserve risers seen at 1:50 (very roughly), and it is noteworthy that the jumper only popped his brakes and increased speed at around 1:45 -- which may have helped extract the reserve.

In any case, whether the reserve popped on opening or some time later, the altitude was not low, and the incident needs investigating.


(This post was edited by pchapman on Dec 17, 2012, 7:39 AM)


mircan  (D 32291)

Dec 17, 2012, 8:15 AM
Post #25 of 26 (2486 views)
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Re: [pchapman] Argus fire and Racer Reserve PC in tow [In reply to] Can't Post

In reply to:
In reply to:
Were you contacted regarding this incident LINK? (*sorry It is on FB, I got the link that way)
They state that "argus fires reserve canopy after main was opened for 30 sconds".
Any more info on that?

Just to be clear for everyone, that is a DIFFERENT incident, so we have two different events being discussed here.

For this "INCIDENT #2":

The facebook video of a jump at Skydive Miami shows a complete two out, with the reserve rising up behind and visible on camera only 40 seconds after opening. But although the jumper's initial thought was that the Argus fired 30 seconds after opening, the video alone can't prove that version of events -- it is possible to have the reserve PC in tow a while and not noticed, until it eventually extracted the bag.

The jumper did see 3500' or so on his alti shortly before his pull, and the timing of the rest of the video doesn't suggest any altimeter issue.

So it wasn't a low pull. Canopy is open at around 1:10 on the video, reserve risers seen at 1:50 (very roughly), and it is noteworthy that the jumper only popped his brakes and increased speed at around 1:45 -- which may have helped extract the reserve.

In any case, whether the reserve popped on opening or some time later, the altitude was not low, and the incident needs investigating.

Yes it is different incident.
Everything stated above is the reason why I`m asking. If it was an AAD fire, It could be easily established by just looking at the device and by loop that has been cut.
If AAD did cut the loop, then why? Wrong mode setting, altitude adjustment or faulty electronics/programming... Either way, I would certainly want to know more. Personally I have no issue with cutter problem, but if is electronic/programming thing, it`s different story.


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