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ernokaikkonen

Racer speedbag

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Donning my "defend John Sherman hat" again.

The point that most posters are missing is that safety-stows are optimized for the low speed edge of the envelope while Speed Bags are optimized for the high-speed edge of the envelope.

Let's do a historical review. When safety-stows were introduced, Balloon suits were in fashion and relative workers were striving for a steady 100 mph freefall, so naturally, safety-stows were optimized for the low-speed edge of the envelope .... and there was that silly TSO requirement about reserves deploying in less than 3 seconds.

Fast forward to the late 1990s. Head-downers were routinely doing 180 mph and starting to blow up over-loaded reserves. The fact that skydivers willfully ignored weight and airspeed limits printed on reserve data panels was quietly ignored. So John Sherman tried to design a reserve bag that would prevent line dump when customers foolishly operated outside the high-speed edge of the TSO envelope.
He resorted to tried and true MIL-SPEC rubber bands which had proven their reliability on thousands of diapered round reserves, the first generation of free bags and millions of main deployments.

While speed-bags may be over-kill for bellytive working POPS, they make a lot of sense for head-downers. Speed bags make the most sense when applied to tandem main deployment bags.
I would really love to install speed-bags on our 30-ish Strong tandems, because they make way more sense than the existing ALS bags which use a mixture of rubber bands and bungees. The problem with bungees is that they are replaced by the least skilled staff members, who do not understand the concept and frequently make them too loose, negating their advantage.

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The guy that started this post is a perfect example of why some people want the old style. There alot of riggers out there who are too busy preaching thier opinion that they don't have the time to listen. If there is proof that they are wrong, then the fault lies in the proof, not thier opinion.

You can't teach a student who refuses to learn.



Ouch! The reason I started the thread*) was described in the first line of my post; "I don't get it". I started by describing my personal opinion and observations of the Speedbag. Since then, I've read many informative posts on the subject. Riggerrob's and Nancy's posts about the Mil-spec rubber bands were especially valuable, since as a new rigger I have very little experience with rubber bands in the reserve. So, I'm now convinced that Mil-spec rubber bands that have not been sitting on a shelf in sunshine for months can be safely used in reserves, as long as they don't come in contact with brass.

As to the Speedbag design, I haven't seen anyone explain koppel's concerns over the seemingly bag locked reserves that he pulled out for a repack. As long as this can not be re-created, we don't even know what causes it, and can't look out for the mistake that makes it happen.

I'm also not convinced that there is a need for a new design; while I agree that there can be problems with safety stows, I maintain that these are most likely caused by worn-out shock cord, broken shock cord, safety stows that are too large, safety stows that are too small, or line bights that are too large or small.

All manufacturers, Jump Shack included, have been able to do all the necessary tests with regular freebags. I don't know what the speeds and weights for these tests are, but if they are not close to freefly speeds, maybe some additional high speed testing of the traditional freebag would be in order? Apparently the traditional design has been tested to freefly speeds.

---
*) and maybe I just wanted to stir some shit.:P

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All manufacturers, Jump Shack included, have been able to do all the necessary tests with regular freebags. I don't know what the speeds and weights for these tests are, but if they are not close to freefly speeds, maybe some additional high speed testing of the traditional freebag would be in order?



"However, test weight must be not less than 264 lb (119.7 kg) and the test speed must be not less than 180 KEAS (333.4 km/h) for reserve and emergency parachute assemblies; for dual harness parachute assemblies for test weight must not be less than 480 lb (217.7 kg) and the test speed must not be less than 210 KEAS (388.9 km/h)."

Sparky
My idea of a fair fight is clubbing baby seals

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Nancy seems to have chosen not to respond.



I asked her to read the original "question". She did within a couple of days. She stated JS does not spend time reading DZ.com (it is too time consuming) so don't be surprised if there is no answer.

rm

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This speedbag discussion was had 3 years ago when it came out. Nothing that has occured in the interim has changed skydiving in any meaningful way. No other manufacturer has adopted a similar design, nor is it likely to happen. Why? Jumpers don't want it. Other manufacturers clearly don't agree with it.

When one person, or company is doing things differently than the rest they might be pioneering new ground, or they may, as someone pointed out, doing things differently only to be different (because they didn't invent it the safety stow).

To answer a few posts:

Line dump is a misnomer, otherwise every base opening would explode the canopy. In case you aren't up to speed on this 25 or 30 year old technique of freestowing the lines, no line stows are used. Just a single locking stow is all that is required. Furthermore, how is it that people are using bags with (gasp), no stows. Search berger bag or stowless bag to learn more.

At 250#, i am within the design parameters of sport gear built to 23c. Yes, I am aware that 10 years after every other gear mfgr stopped using velcro, JS finally realised that they were wrong. Many of you will remember that JS was equally sure that they were the only ones who "got it" with regards to velcro, and that those nasty tuck tabs would wear out too quickly, stay closed when you didn't want them to, and open when you didn't want them to. No velcro on new Racers you say? They use tuck tabs now? Oh my. Give JS another 10 years and the speedbag will be where their beloved velcro is now, the trashcan.

Or maybe I'm wrong and every gear builder will be building velcro laden wondehog rip offs with round reserves, and of course, speedbags. ;)

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Just a thought,

there was a service bulletin put out by JumpShack in Jan 2001 that "Strongly Recommended" the removing of the freestow pouch and the attaching of Type 3 Ribbon Weave according to their instructions for the use of Mil Spec bands for line stows.

This makes sense if you are concerned about 'Line Dump' for high speed flyers like Freefliers. There is no potential for a bag lock (more than any bag has with the locking stows ) and gives an orderly staged deployment with good acceleration of the bag.

This Works. Many manufacturers use these on their main d-bags as well, including....wait for it........Jump Shack.

Why was it nesseccary for the second flap to be introduced?

I would appreciate being educated on this point as I find nothing else wrong with Racer's and have many clients who choose to jump them.
I like my canopy...


...it lets me down.

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I am aware that 10 years after every other gear mfgr stopped using velcro, JS finally realised that they were wrong.



they offer 3 styles. They just responded to the market (yes, perhaps a little slow). Nothing wrong with velcro. I have an NOS (velcro top and sides) and would not trade it for anything - nothing more comfortable I have tried and I sell lots of used gear. I think one thing about owning a racer is you don't give a shit what anyone else thinks - kinda like John Sherman I think.

rm

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I think one thing about owning a racer is you don't give a shit what anyone else thinks - kinda like John Sherman I think.

rm



I was not going to post anymore on this thread Rob, but THAT made me :ph34r::D
Pete Draper,

Just because my life plan is written on the back of a Hooter's Napkin, it's still a life plan.... right?

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Prejudice never shows much reason!
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This speedbag discussion was had 3 years ago when it came out. Nothing that has occured in the interim has changed skydiving in any meaningful way.

According to whom, you? Clearly you do not know what is going on in the industry.
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No other manufacturer has adopted a similar design, nor is it likely to happen. Why? Jumpers don't want it. Other manufacturers clearly don't agree with it.

Then why are two other manufactures using a speedbag version of their own design. And why is one of the top military canopy/container manufactures using a speedbag type design? Also, customers keep buying them from JS, why? I guess because everyone else is just not as smart as you.
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When one person, or company is doing things differently than the rest they might be pioneering new ground, or they may, as someone pointed out, doing things differently only to be different (because they didn't invent it the safety stow).

What does the reason matter? Reality check, this happens in business every day.
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To answer a few posts:

Line dump is a misnomer, otherwise every base opening would explode the canopy.

Dam, PD, RWS etc.…… are wrong again.
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In case you aren't up to speed on this 25 or 30 year old technique of freestowing the lines, no line stows are used. Just a single locking stow is all that is required.

Not on high speed deployments.
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Furthermore, how is it that people are using bags with (gasp), no stows. Search berger bag or stowless bag to learn more.

And why have there been problems with them? And using your statements above why haven’t all of the other manufacturers jumped on the wagon?
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At 250#, i am within the design parameters of sport gear built to 23c. Yes, I am aware that 10 years after every other gear mfgr stopped using velcro, JS finally realised that they were wrong. Many of you will remember that JS was equally sure that they were the only ones who "got it" with regards to velcro, and that those nasty tuck tabs would wear out too quickly, stay closed when you didn't want them to, and open when you didn't want them to. No velcro on new Racers you say? They use tuck tabs now? Oh my. Give JS another 10 years and the speedbag will be where their beloved Velcro is now, the trashcan. Or maybe I'm wrong and every gear builder will be building velcro laden wondehog rip offs with round reserves, and of course, speedbags.

There is nothing wrong with Velcro as long as like anything else it is maintained, the industry responded (JS included) to custom desires. Every major manufacturers military systems have Velcro riser covers including Sun Path, RWS and Paraflite and you can still get (yes customers still order them) Velcro riser covers on sport rigs.

Oh, Wonderhog by the way does have an “r” in it.

Stay safe
Time and pressure will always show you who a person really is!

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Line dump is a misnomer, otherwise every base opening would explode the canopy. In case you aren't up to speed on this 25 or 30 year old technique of freestowing the lines, no line stows are used. Just a single locking stow is all that is required. Furthermore, how is it that people are using bags with (gasp), no stows. Search berger bag or stowless bag to learn more.



Like I said, I don't think line dump means what you think it means.

I hate to break it to you but "line dump" is not the meterd release of free stoed lines. Line dump is when (here it is) lines release out of sequence and allow the canopy to inflate prior to line stretch.

This phenomina can be prevented by having a reliable locking stoe or stoes. If you are unfamiliar with this technology, I sugest you look at any freebag (they have locking stoes) or even the base canopy you yourself mentioned.

Line dump can still occur if your locking stoes fail, I doesn't matter if the rest of the lines are elastic banded, freestoed or shoved up your butt.

"but" you may ask "how can locking stoes fail?"

Well, when a PC inflates, it does not pull the canopy out of the container, it pulls the bag.

First, lets talk about main bags and line dump.

Objects at rest (relative to the jumper) like to stay at rest. When the bag excellerates of the back, the canopy wants to stay put. Stress is out on the locking stoes. On a many conventional main bags, that is usually 2 40lbs elastic bands.
Sounds like alots but the larger the canopy or the faster the freefall speed, the greater the force exerted on the locking stoes. But now you think, "if I have 2 locking stoes, that's 80lbs! my canopy would have to experience over 10 gs of exelleration!"

Well, right you are chief BUT if the elastics are worn from use, that 40lbs elastic may only take a couple of pounds to break. When that happens, the bag leaves the container followed by an already inflated main canopy! wow. That'll make your heart shoot out your own ass!.
"But", you say "my container has 3 (or even 4) locking stoes"
Well good for you. You are coming to the same conclusion Jumpshack has come to. The more locking stoes, the less likely hood of out of sequence openings. You have just invented a speed bag which has multiple locking stoes.

Or perhaps you went the other way and decided to make a Safety stoes that doesn't break at all. Hey what's wrong with that? (besides the prospect of having something locking your bag that won't break)

Well, if you remember PDs experience with Tube stoes and their ban from fatally hard openings, you'll realize that a stoe can come undone as the bag lifts off you back.

"but", you say "who cares if a stoe comes undone, I've got more than one locking stoe!

Ah, my poor foolish friend. If one stoe goes on a safety stoe, the other is not far behind and the last thought you'll have is ...
"ohhh.....That's line dump."

Why a speed bag
1.) superior metering of lines
2.) superior protection from dump
3.) Why do we use elastics? (everyone together now) because they break.

*disclaimer* I know I've left sail effect. Free stoe guy wouldn't believe it anyway.
My appologies to the guy who had his lines wrap around his freebag when they dumped out the pouch. Or more accurately, his family.
I would rather be a superb meteor, every atom of me in magnificent glow, than a sleepy and permanent planet.

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Then why are two other manufactures using a speedbag version of their own design. And why is one of the top military canopy/container manufactures using a speedbag type design?



Could you name these manufacturers? I'd like to learn more about these designs, is there anything available on the Net?

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Line dump is a misnomer, otherwise every base opening would explode the canopy.


Dam, PD, RWS etc. are wrong again.



"Line dump" is a misnomer! Simultaneous deployment of all lines doesn't matter as long as the canopy doesn't start deploying before line stretch. "Canopy dump" *) or "bag strip" **) would be better names. They all describe the same event though.

*) canopy is dumped from the bag/released from the locking stow before line stretch
**) bag is stripped off the canopy before line stretch

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Furthermore, how is it that people are using bags with (gasp), no stows. Search berger bag or stowless bag to learn more.


And why have there been problems with them? And using your statements above why haven't all of the other manufacturers jumped on the wagon?



The stowless designs do have problems of their own. Regular hard openings due to bag strip isn't one of them; I've spent two seasons packing those bags and they work just fine.

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Your explanation of line dump is excellent except i think a lot of people have come to call it bag dump to keep people from thinking stowless bags would create harder opening.

And if this were true about reserve bag dumps being such a problem, would RWS hav found evidence of this in their testing of the skyhook rsl system? I mean a fully inflated main canopy spinning at a high rate of speed is going to pull more force on a freebag than a p/c in the relative wind, right?

Johnny
--"This ain't no book club, we're all gonna die!"
Mike Rome

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Could you name these manufacturers? I'd like to learn more about these designs, is there anything available on the Net?

I could but I will let them speak for their own companies and I don’t know what is available on the net.
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"Line dump" is a misnomer! Simultaneous deployment of all lines doesn't matter as long as the canopy doesn't start deploying before line stretch. "Canopy dump" *) or "bag strip" **) would be better names. They all describe the same event though.
*) canopy is dumped from the bag/released from the locking stow before line stretch
**) bag is stripped off the canopy before line stretch

My previous statement was factual.
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as long as the canopy doesn't start deploying before line stretch.

I would consider that a big reason as to why it matters and has killed people! Especially when it is preventable.
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The stowless designs do have problems of their own. Regular hard openings due to bag strip isn't one of them; I've spent two seasons packing those bags and they work just fine.

Would you like to tell me which of the two sentences is true, since they both can’t be?
Time and pressure will always show you who a person really is!

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Well, if you remember PDs experience with Tube stoes and their ban from fatally hard openings, you'll realize that a stoe can come undone as the bag lifts off you back.



I don't remember anything of the sort. Are you saying that PD recommends against using Tube stoes? Can you refer me to a source where this is stated?

I just downloaded "How to Prevent Hard Openings" from PD's website. Here is a quote from that document:
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If you use Tube Stoes, look at the instructions that were included with them. Follow the instructions labeled "For tighter Tube Stoes". Rubber bands can be tightened in the same way. Replace Tube Stoes or rubber bands that appear worn.



It doesn't seem to me that PD has banned the use of Tube stoes. Maybe I misunderstood your post?

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I hate to break it to you but "line dump" is not the meterd release of free stoed lines. Line dump is when (here it is) lines release out of sequence and allow the canopy to inflate prior to line stretch.



No, that is called "canopy dump" or "bag strip".
----------------------------------------------
You're not as good as you think you are. Seriously.

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My previous statement was factual.



We're talking about the same event here, and we agree that it's Very Bad(tm) when it happens. I just think that "line dump" isn't very descriptive, and may give the wrong impression. Therefore I prefer to use one of the alternative terms I mentioned.

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The stowless designs do have problems of their own. Regular hard openings due to bag strip isn't one of them; I've spent two seasons packing those bags and they work just fine.


Would you like to tell me which of the two sentences is true, since they both can't be?



Both sentences are true. I could expand on on the second one by adding: (...)they work just fine, as long as a canopy with the correct pack volume is correctly packed into the bag.

The first problem is that the bags I packed were very critical of the size of the canopy packed into it; it was more or less 'one bag, one canopy'.

The second problem was that it was quite easy to pack a baglock if you didn't know what you were doing; when properly packed, they worked just fine.

I didn't intend to go to this in much detail, as stowless bags are a topic for another thread.

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I hate to break it to you but "line dump" is not the meterd release of free stoed lines. Line dump is when (here it is) lines release out of sequence and allow the canopy to inflate prior to line stretch.



No, that is called "canopy dump" or "bag strip".



You may have missed the first part where I said "Lines release out of sequence". That is line dump. but we are arguing symantics and basically pissing in the wind.

Can we agree that we are talking about out of sequence openings no matter what the name?
I would rather be a superb meteor, every atom of me in magnificent glow, than a sleepy and permanent planet.

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In Reply To
Well, if you remember PDs experience with Tube stoes and their ban from fatally hard openings, you'll realize that a stoe can come undone as the bag lifts off you back.

I don't remember anything of the sort. Are you saying that PD recommends against using Tube stoes? Can you refer me to a source where this is stated?



Sorry, that maybe a little before your time.

It goes back to the early 90s when Sabres (and ZP3 in general) were first introduced. If I remember right, there was a rash of brutal opennings and even a fatality. I had a Sabre then and was told that tube stoes were verbotten because they caused line dump. I'm sure I read it.
I'll check an old Sabre manual if I can find one and see if it's in print. Or perhaps someone else can shed some light on this, it may have only applied to Sabre1s which are no longer made.

Oh god, I hope this doesn't become a "Sabre 1s had shitty opennings" thread. My appologies if it does.
I would rather be a superb meteor, every atom of me in magnificent glow, than a sleepy and permanent planet.

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You may have missed the first part where I said "Lines release out of sequence". That is line dump. but we are arguing semantics and basically pissing in the wind.



Actually, calling line dump more than what it is... is fairly annoying. Line dump is blamed far to often for hard openings when it simply isn't the case. It is only an out of sequence *deployment* if the bag is stripped off the canopy before line stretch. If the locking stows stay closed until line stretch has occurred, then whatever happened to the rest of the lines before that point, simply doesn't matter.

This entire debate is whether or not the standard design will keep the bag closed until line stretch ensuring the deployment is in sequence.
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The remainder of this post is a repeat of what has already been stated and is not directed at anyone.

Bag Strip = Deployment bag being yanked off the canopy before line stretch. <==this is Bad(tm)

Line dump = lines falling out of some (or possibly all) of the line stows.

If the lines actually fall out of the locking stows...the bag will strip off the canopy.

The latter scenario is more likely during a very high-speed deployment and keeping that from happening is what this is all about.
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Regarding the speed bag design:

I have packed only one Racer with the speed bag design. I have not seen a low speed deployment (or any speed deployment for that matter) when speed bag was used.

The perceived problem is obvious. *Note the word perceived* I have nothing to go by to have an educated opinion.

I personally would like to see some side-by-side tests. The test would be very low speed simultaneous cutaway and reserve pulls. That would show us how quickly the reserve deploys using a speed bag and a standard freebag with a properly sized safety stow.


If they have already occurred and I would think they have, then release the videos.

Prove it by showing the masses it's a good design. I'm not saying it is or it isn't a good design, but if all us common folk have to go on, is the advertisements, and some very carefully selected words in a post, then how can the people with doubts have those doubts put aside?
My grammar sometimes resembles that of magnetic refrigerator poetry... Ghetto

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I was so impressed with the design that I put one on my main and reserve.



You can’t compare a main D-bag with a reserve free bag. They are apples and oranges. On a main bag the pilot chute is attached to the canopy so it would be real hard to have “bag strip” without ripping a hole in the top of the canopy.

I have been jumping the bag in the attached pictures for over 1000 jumps. It is used with a 245 sq. ft. Sharpchuter, 10.8 pounds. The 2 locking stows are tube stows with the remainder of the lines in a side pocket much like a reserve free bag. I have yet to experience an out of sequence deployment or a hard opening due to anything related to the bag. It reduces bag whip and the lines are staged with much less chance of catching on all the extra stows.
This is not a theory; it is something that has been proven over 1000 times.

Sparky
My idea of a fair fight is clubbing baby seals

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Nancy seems to have chosen not to respond.



I asked her to read the original "question". She did within a couple of days. She stated JS does not spend time reading DZ.com (it is too time consuming) so don't be surprised if there is no answer.

rm



She found time to read and respond twice to this thread.:S

Spakry
My idea of a fair fight is clubbing baby seals

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Sorry Sparky but your bag's no good.....

......its got Velcro :o

Now if you made it with Tuck Flaps....well that would keep all those people out there in No-Velcro Land happy (and it would be free-fly friendly?!? :S)

Koppel
I like my canopy...


...it lets me down.

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