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Major reserve hesitation

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RiggerLee

The honest answer is that although it's potentially superior in performance no body wants to do it. Why? Do you realize what kind of convoluted, monkey fucking a football, Roul Goldburg, bull shit you have to go through to pack one of those things? And yes I know all the fucking secrets. I'm the one that gets all that shit dumped on him because no one else wants to deal with it.

This is the truth. They can be somewhat more difficult but the main thing is that they take a slightly different skill set and they can take more time. People don't want to deal with it. Some flat out wont deal with it. And some people like me who can do it get pissed about having it all dumped on them because no one else wants to learn to do it.

Lee



Sounds like you don't wanna do it either ;)

What's more 'Rube Goldberg' ~

- having a system that is safer but more maintenance intensive...function over form.

- having a system that looks pretty, packs easy, but under certain circumstances won't perform within industry standards...form over function.

Hate to spend the last 5 seconds of my life thinking "...but the good news is at least my rigger liked packing it"

:ph34r:










~ If you choke a Smurf, what color does it turn? ~

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As an aside:
How do containers that have the reserve pilot chute external but still underneath 2 flaps compare to a pop top and completely covered pilot chute

Im thinking of a vortex2/wings/javlin odyssey.

Are these closer to a pop top due to less flaps on top of the reserve or is the design fundementally different because the pin is still on top ( i think it is on top at lease)

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Poptop safer? I don't buy it, epecially the "semi poptop" rigs. The reason is that although they likely will get the p/c into the air faster without having to push flaps aside, that doesn't seem to be the current problem.

The problem is rigs that are slow to extract the bag once the p/c is in the air. Rigs that have the p/c under 4 flaps have large strong springs that do the job, it is a non issue. They also have larger p/c s that I speculate (yes, I expect to hear opinions on this) are capable of generating more force from less airspeed than the smaller ones used by the more exposed versions.

What good is it to get it into the air if it doesn't produce enough force to pull the bag out of the tight container? As far as I'm concerned. the Vector balute type p/c is the best at this, it works even on large Sigmas. Talons also have large ones. I feel that looking at your p/c cap on the outside and thinking that it makes you safer is a false premise. I will grant the the Racer solves the problem by eliminating the tight container.

Does anyone here know how much force is generated by a Vector versus a Wings p/c?
Always remember the brave children who died defending your right to bear arms. Freedom is not free.

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The problem is rigs that are slow to extract the bag once the p/c is in the air. Rigs that have the p/c under 4 flaps have large strong springs that do the job, it is a non issue. They also have larger p/c s that I speculate (yes, I expect to hear opinions on this) are capable of generating more force from less airspeed than the smaller ones used by the more exposed versions.

What good is it to get it into the air if it doesn't produce enough force to pull the bag out of the tight container? As far as I'm concerned. the Vector balute type p/c is the best at this, it works even on large Sigmas. Talons also have large ones. I feel that looking at your p/c cap on the outside and thinking that it makes you safer is a false premise. I will grant the the Racer solves the problem by eliminating the tight container.

Does anyone here know how much force is generated by a Vector versus a Wings p/c?



You are correct in your analysis but the spring only gets the PC out if the container. Once it is out of the container and at the end of the bridle it is the Drag capability of the PC that matters as it must overcome the container retention of the bag. Evaluation of the PC must be in terms of "Effective Square Feet". This is necessary because the other parameter is Dynamic Pressure which varies with Speed and altitude. The Dynamic Pressure is in terms of Pounds per Square feet and the Effective Size is the Square feet with witch you multiply to find Pounds of Drag. The only way to properly test pilot chutes is in a wind tunnel. There are other ways but they are not yet proven.

Now what is "Effective Square feet". This term is the combination of the actual measurable size of the PC canopy and it's "Coefficient of Drag". The Drag coefficient is sufficient to evaluate the device but not to calculate the drag. Some manufactures will not state the physical size of their PC's but that doesn't matter if we use the combined results.

Back in 1988 I was the principal investigator in development of mid-air refueling drogues. In that project, which was conducted at NASA Ames by NASA personnel, we tested 3 pilot chutes in common use. The Vector 1 and the Vector 2 and the Racer 36".

The Racer and the Vector 1 are conventional pilot chute with about half mesh and half canopy cloth. The Vector 2 was the one in common use to day and it similar to the Wings and Infinity pilot chutes.

The results are in terms of “Effective Square footage" are: Vector 1 = 5.6 Sq Ft., Racer = 5.8 Sq. Ft., Vector 2 = 2.3 Sq. Ft.

If the Dynamic Pressure is, say, 3 pounds per sq. Ft. which it is 1 second after a cutaway at 2000 Ft from a Mal which was descending at 20 FPS. The results in terms of drag are as follows.

Vector 1 = 3PSF * 5.6 Sq. Ft = 16.8 pounds
Racer = 3PSF * 5.8Sq. Ft. = 17.4 pounds
Vector 2 = 3PSF * 2.3 Sq. Ft = 6.9 pounds


The results found by NASA and broadcast over this form for the past several years predicted the performance by certain product being discussed here.

Here is the proof: https://www.youtube.com/watch?v=Zva4gHVX_zI

Some people will not believe Science when it is too complicated or not convenient.

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The Vector 2 was the one in common use to day and it similar to the Wings and Infinity pilot chutes.




I've not actually seen an Infinity p/c, but I've seen many Wings and Vectors. In what way are these two similar? They look to be very different to me.
Always remember the brave children who died defending your right to bear arms. Freedom is not free.

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That is interesting, but it only tells us the difference between the three different products in one sample in 1988. I agree that the Racer system has several advantages in regard to potential speed of reserve deployment. But it may be that it is the Racer p/c that is the outlier in terms of extraction ability.

What I'm wondering about is not the already proven difference between Racer and everything else, but the difference between Vector type and Wings/Javelin ect. type systems. I suppose in the end that the force generated by a sub-terminal cutaway may be a lot more important than that generated in a wind tunnel at high speeds. Although the fact that the drag increases by the square of the speed would seem to indicate that one can predict the other.
Always remember the brave children who died defending your right to bear arms. Freedom is not free.

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Here is a photo of a wings lifted from their web site.
[inline Wings_pilotchute.jpg]

Notice that 80% of the canopy is canopy cloth.
While the Vector 2 might not be of the same proportions it still has more than 50% canopy cloth as does the Infinity, or so I am told. Information which I have not personally verified.
The point is that, on all 3, the canopy cloth which extends beyond the equator of the canopy is deflecting air not grabbing it.

The BS about getting it into the air stream is just that, BS. Things don't go up when released in FF they continue to fall at the same rate at which they were released unless their mass density is different or they reach the end of the bridle and start dragging. If the mass density is less they will slow down, if more they will accelerate.
This is the baine for heavy springs and tops. As Bill noted, when he tested the Tear Drop, the PC accelerated away from the free falling body when released because of the heave metal hat. The same is now true for the big disk on some rigs which are combined with heave springs.
Pilot Chutes should be as lite as possible so they will allow you to fall away from them. But it is the canopy design which does the dragging and non traditional designs have proven not to be of adiquet drag capability.

The data has been out there for 25 years and the marketing has overcome it to the detriment of the sport.

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Now that's got me wondering. I can see intuitively why a p/c that is shaped like a parachute could be more effective for the size than one shaped like a balloon. Has anyone ever attempted to make a man sized balute type parachute? Would the oscillation be extreme?
Always remember the brave children who died defending your right to bear arms. Freedom is not free.

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Now that's got me wondering. I can see intuitively why a p/c that is shaped like a parachute could be more effective for the size than one shaped like a balloon. Has anyone ever attempted to make a man sized balute type parachute? Would the oscillation be extreme?



Now that's a good question. To my knowledge the answer is no. If you want to know more about Ballutes you can find information in the Parachute Design Recovery Manual. This is the manual used by military and government designers. It may be down loaded from here: www.jumpshack.com I don’t have the exact URL and their site is currently down. Navigate to Home page and to Downloads, you will find it there.

A Ballute is defined as a Supersonic Stabilization Drogue. It provides enough drag, without noticeable oscillation, to stabilize the store at over 600MPH.

A fancy word which was used to baffle people into thinking it was something special when it actually almost used correctly. The thing which is call a Ballute in our sport would have to go to supersonic speed to get enough drag to extract some of the tight fits I have seen.

Quote

From The Parachute Design Recovery Manual, page 5.06 & 7

5.8.3 Balloon-Type Inflatable Decelerators
Several configurations of inflatable balloon-type decelerators have been investigated. So far only the ballute, developed by the Goodyear Aerospace Corporation under government contract (Reference 5.135), has been used operationally at subsonic and supersonic velocities.
The configuration of the ballute, also called attached inflatable decelerator (AID), is illustrated in Figure 5-97. The balloon-shaped rear and center part is a tension shell; the conical forward part carries the loads to a junction point for connection with the fore body. A burble fence around the equator of the ballute creates a uniform flow separation, thereby eliminating destabilizing forces. The burble fence and the inverted conical front part together provide good stability. Air scoops in front of the burble fence ram-air inflate the ballute. Inflation with stored gas or gas generators has been investigated but was replaced with the simpler ram-air inflation method.


Known applications of the ballute are the stabilization/retardation device for the Gemini spacecraft back-up ejection seat with an upper deployment limit of Mach 4 at 80.000 feet altitude, and the low-altitude retarder for the Mk 82 bomb.

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gowlerk

Now that's got me wondering. I can see intuitively why a p/c that is shaped like a parachute could be more effective for the size than one shaped like a balloon. Has anyone ever attempted to make a man sized balute type parachute? Would the oscillation be extreme?



Something kind of close to the topic:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=1900460#1900460

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You toss around the term Ballute style PC. Just to be clear there really is something called a ballute. It doesn't have any thing to do with pilot chutes. Apples and oranges. A Ballute is a drogue designed to operate at high speeds. It's design is driven by concerns of shock wave and heat management. One of the main characteristics is that it does not have an open bottom. They are generally inflated with compressed gas or have small vents near the equator. Drag is generally Not the driving design criteria. Survival at Mach is. There is more then enough drag at that point. They often have a burble fence to increase there stability when sub sonic. It breaks off the air flow from the side at a certain point so it has very little oscillation. Most of these designs have a drag coefficient which is... unimpressive. To be honest they down right suck as a parachute.

None of this has any thing to do with PC designs. I don't know what would inspire some one to build a... parabolic PC. That's probable a better term. As I recall a Parachute with mouth narrower the equator is referred to as parabolic. The T-10 is a parabolic canopy and works well. Why you would take this concept to such an extreme, as in the vector 2 pc, I don't know. Maybe he was having trouble with blowing them up at high speeds during his tandem testing. I don't know, ask booth. The only question is whether it makes enough drag. And that relates to the system as a whole.

Lee
Lee
[email protected]
www.velocitysportswear.com

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RiggerLee

The honest answer is that although it's potentially superior in performance no body wants to do it. Why? Do you realize what kind of convoluted, monkey fucking a football, Roul Goldburg, bull shit you have to go through to pack one of those things? And yes I know all the fucking secrets. I'm the one that gets all that shit dumped on him because no one else wants to deal with it.

This is the truth. They can be somewhat more difficult but the main thing is that they take a slightly different skill set and they can take more time. People don't want to deal with it. Some flat out wont deal with it. And some people like me who can do it get pissed about having it all dumped on them because no one else wants to learn to do it.

Lee



This is a very unfortunate side effect of the Racer and my experiences to date do in fact reflect a change in attitude about the difficulty or perhaps better said the perceived difficulty of packing the two pin pop tops...

but there is a huge difference in performance V packing ease as a topic of discussion.

The two are separate issues. No one has the history or statistics to support the idea that the two pin is less safe than any other. And this is a very disappointing way of thinking to me. Because the more we speak about this particular aspect of the racer design it gets associated with malfunctions and a host of other rhetoric,... that is just wrong!

I don't even like posting here about this aspect of a racer because of the maligned associations that this myth has created over time. It may very well be that having two pins is in fact a better, statistically speaking, system!

Not to carjack this thread, but packing should be an independent variable and not something that continues to be dredged up from the bottom of the pile of stuff that the majority of people out there bring up every time this design discussion takes place.

I know many riggers out there that don't like packing the two pins. To me riggers that loudly express their personal feelings about rigs that are easy to pack in comparison are also holding up a sign that they don't fully take an interest in their customers and they are also holding up a sign that says they take the easy road! Well I want a rigger that knows her or his shit. If you can't pack a Racer then your not going to get my business nor my respect. It really is like holding up a billboard that says: I'm lazy and ignorant.

C

I'm certainly not dissin rigger Lee at the moment, he sounds like a straight forward matter of fact guy! :)
Racers pack their reserves differently, you can either learn like Lee to do it and do it well or just go for the fast buck and continue to dis an exceptional product for your own selfish reasons.

Exceptional riggers have a reputation and over time they probably end up packing more racers than their neighbors. Their commitment to skydiving is apparent as is their dedication to safety and performance. If your rigger can't pack a Racer move on,...and this has more to do with than just not liking to pack one, than not.

If you can't or wont pack my Racer cause it takes 5 minutes longer then I can certainly take ten minutes to find someone else!
But what do I know, "I only have one tandem jump."

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I just ran some numbers. For 200 lb exit weight to achive a 20 ft/sec decent rate you would need some thing 28 ft in diameter. Please understand that I'm talking the inflated diameter of the main body which is my reference. That canopy would have the pack volume and weight of a... 80 ft diameter canopy? I don't know, i'd have to pull up the other program and start looking at panel shapes. But that should give you an idea of the relative efficentcy of the design in comparison to a real "Parachute".

Lee
Lee
[email protected]
www.velocitysportswear.com

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Ok, I've got it. It is not a ballute. And I've done some searching and now see that the controversy between Bill and John over p/c design is old news. I'm sorry I brought it up again.

I still would like to know why we have had so many too late to inflate reserve fatalities after AAD fires and what we can do about that. There is no investigative body to look at this. I'm sure there are people who know, but none are saying.
Always remember the brave children who died defending your right to bear arms. Freedom is not free.

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And there you go changing the whole question. Once you add in an AAD fire the whole question changes. Now if you are cutting the loop it raises whole new questions of flap design, cutter location, spring strength and top diameter, etc. And that's all long before the drag of the pilot chute or the tightness of the tray becomes an issue.

Lee
Lee
[email protected]
www.velocitysportswear.com

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gowlerk

Ok, I've got it. It is not a ballute. And I've done some searching and now see that the controversy between Bill and John over p/c design is old news. I'm sorry I brought it up again.

I still would like to know why we have had so many too late to inflate reserve fatalities after AAD fires and what we can do about that. There is no investigative body to look at this. I'm sure there are people who know, but none are saying.



I think that is the core issue. The current structure, coupled with people keen to sue is broken.

People are too dumb to realise that all design involves tradeoffs AMD mistakes. An independent body with teeth has the ability to dig into root cause analysis and provide a meaningful report.

Instead we are left with arse covering, finger pointing and marketing to soft through... Also while good designers are usually the biggest critics of their own design, it is human nature to defend your 'baby', throw in the fact that nowadays any admission of a mistake will get you roasted, I really doubt you'll see any manufacturer admit to a tradeoff too far or mistake...
Experienced jumper - someone who has made mistakes more often than I have and lived.

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So we don't know if these AAD firing fatalities involve p/c launch hesitation related to using a cutter or if they are related to slow to extract dbags. Or both, or neither? And as far as we know no one is looking to find out, or if they are they don't want to speak of it.

I guess the closest we can come to an understanding is that there is a move by the industry to raise activation altitude. It may go a long way to solving the problem without anyone having to acknowledge that there even is a problem.

Oh well, sport skydiving is a risk activity. The main public exposure is through tandem where the rules keep us safer. Maybe we have no right to expect more from the PIA. I'm guessing there are many within the industry that understand exactly what the problems are. Maybe Mr. Sherman has been correct all along. Even if he does sometimes sound like a conspiracy theorist.
Always remember the brave children who died defending your right to bear arms. Freedom is not free.

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You are basically correct. but I don't think it's fair to say that no one is looking to find out. I have no doubt that people are taking a great interest in this. But you are correct that they are so far silent. I suspect that they have come to similar conclusions. That there are no easy solutions. That we will over time have to change and up date our pattern sets and over time build our way out of this just like we built our way into it. I started another thread in gear and rigging tossing out ideas of how we might fix some of this but there has been very little interest shown in it. I thought they were reasonable ideas. But how can you go forwards with changes when there have already been fatalities? Their lawyers may be telling them that there hands are tied for the next X number years till the time limit on the death is up. That's why I was asking about the possibility of FSDO approval for after market changes to the rigs that might help with the problem.

Lee
Lee
[email protected]
www.velocitysportswear.com

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Ok, I've got it. It is not a ballute. And I've done some searching and now see that the controversy between Bill and John over p/c design is old news. I'm sorry I brought it up again.



Bill called it a Ballute I didn't.
You don't have to believe me but the NASA results are irrefutable.
It may be old news but you should still listen to both sides.
There are 3 possible reason for the late inflation or lack there of.
1. Low drag pilot chute.
2. High bag extraction forces.
3. AAD firing late.

Take you choice and follow it to a conclusion, then choose another and follow it until you know the reasons.
You bet people know, and seriously, the root cause may vary slightly form rig to rig. Some have high extraction and a normal pilot chute. Some have low extraction and a low drag pilot chute and some have both and it varies from model to model with each product line. The real problem is that some of those manufacturers don’t know. How many manufacturers do you know who can tell you what their pilot chutes actually drag in any environment.
The only answer is a standard with metrics for the rigger to check at each inspection cycle.
The extraction force should never exceed 18 pounds is a tenant of the standard I would propose.
Pilot chutes should be placarded with their “Effective Sq. Ft.” is another tenant I would suggest.
If that “Effective Sq. Footage” is less than 6 then it won’t extract the 18 pound pull on a maxed out container. You will have to wait until the speed builds up a bit.

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If that “Effective Sq. Footage” is less than 6 then it won’t extract the 18 pound pull on a maxed out container. You will have to wait until the speed builds up a bit.



That would not explain reserves opening too late from AADs firing at terminal velocity. Do you think that those are basically caused by late firing for whatever reason? The recent Florida double fatality comes to mind here. Surely these guys were falling fast enough for there p/cs to be effective. Perhaps it is well known in Deland through the grapevine what actually happened. But out here it's a mystery to us. I guess if I take my choice from your options menu, late firing would be the logical answer.

Late cutaways resulting in fatalities are understandable. No pulls or late pulls are as well. But what is the point of an AAD if it fires too late?

I have begun scaling freebags from packed rigs that come in for service. But it's just for my curiosity so far. There is no standard I can apply. Although I will be handing out free advise to customers.
Always remember the brave children who died defending your right to bear arms. Freedom is not free.

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In an attempt to steer the discussion back to dealing with this specific incident (as I am a Wings owner, so am concerned about this):

Someone asked about about the details of the container. In the YouTube comments to the video (http://www.youtube.com/watch?v=SyjpgURZVuA) the jumper said "The container is a Wings W-30 if I remember correctly. The reserve is a PD 253. It is the original reserve that came with the container."

If this chart (http://www.garlyn.co.nz/wings/Wingsizingchart2.html) is accurate (it's not from the Wings site, but apparently that of a Wings dealer who hasn't updated their web site since 2009, but it reads as if it was written by Wings), a W-30 is rated to hold a "PD 253R, a Raven-M 282, or a PD 281R (tight)".

So if the sizing chart and the information provided about this particular rig is accurate, it appears that the reserve was the right size for the container (as opposed to a "tight" fit).

And so a chop from above 2000 ft or so from a low speed mal and a nearly instantaneous reserve handle pull (resulting in a rapid PC deployment to full bridle extension) but left him in the saddle at ~600 ft and fired his AAD(!) is a bit unnerving for me to contemplate.

If this is container-specific, should I:
- incorporate "pull on reserve bridle to extract reserve" as a necessary step in my EPs? (As that appeared to be required in this reserve deployment: http://youtu.be/VKVAtjfGjp0?t=1m33s)?
- Get a new pilot chute?
- Get a different container?
- Get Wings' MARD option installed?
- Downsize my reserve?
- All of the above?

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Divalent

In an attempt to steer the discussion back to dealing with this specific incident (as I am a Wings owner, so am concerned about this):

Someone asked about about the details of the container. In the YouTube comments to the video (http://www.youtube.com/watch?v=SyjpgURZVuA) the jumper said "The container is a Wings W-30 if I remember correctly. The reserve is a PD 253. It is the original reserve that came with the container."

If this chart (http://www.garlyn.co.nz/wings/Wingsizingchart2.html) is accurate (it's not from the Wings site, but apparently that of a Wings dealer who hasn't updated their web site since 2009, but it reads as if it was written by Wings), a W-30 is rated to hold a "PD 253R, a Raven-M 282, or a PD 281R (tight)".

So if the sizing chart and the information provided about this particular rig is accurate, it appears that the reserve was the right size for the container (as opposed to a "tight" fit).

And so a chop from above 2000 ft or so from a low speed mal and a nearly instantaneous reserve handle pull (resulting in a rapid PC deployment to full bridle extension) but left him in the saddle at ~600 ft and fired his AAD(!) is a bit unnerving for me to contemplate.

If this is container-specific, should I:
- incorporate "pull on reserve bridle to extract reserve" as a necessary step in my EPs? (As that appeared to be required in this reserve deployment: http://youtu.be/VKVAtjfGjp0?t=1m33s)?
- Get a new pilot chute?
- Get a different container?
- Get Wings' MARD option installed?
- Downsize my reserve?
- All of the above?



Hi Peter,

RSL would help slightly in reducing the delay post cutaway and is a good idea. BUT as you know it doesn't solve the root cause. Sadly we have very little data publicly available on which containers are exhibiting these problems.

It would be a shame to move from a Wings to Brand X to find that Brand X was less reliable than the Wings. We are probably at the point where the only rig that can be truly trusted for this failure mode is a Racer (I don't jump one, and never have). Certainly John is the only manufacturer drawing attention to this problem, everyone else is pretending it doesn't exist.
Experienced jumper - someone who has made mistakes more often than I have and lived.

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