Racer speedbag

[jumpwally 0]

John, Thanks for the info, its awesome to have a mgftr/owner answer questions. i know you don't enjoy this type of media and i'm sure you'll be very frustrated at the way this forum chops up its own over tiny c.... hairs, i for one thank you for your time.

smile, be nice, enjoy life
FB # - 1083

[mjosparky 3]

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John, Thanks for the info, its awesome to have a mgftr/owner answer questions. i know you don't enjoy this type of media and i'm sure you'll be very frustrated at the way this forum chops up its own over tiny c.... hairs, i for one thank you for your time.

There used to be a lot more of this type exchange with the old guard manufactures. If you wanted to know something about a particular rig the manufacture would take the time to explain things. But over the years is seemed that the same manufactures spent more of their time defending their products to jumpers who didn’t have clue how various components part interact with each other. It got to the point where some local skygod would comment on some piece of gear and the next thing you knew it was a documents fact. Skydivers got to where they thought they could absorb the needed knowledge through osmosis. No one wanted to put in the time and effort to learn the basics of gear and build on that. I am surprised that John, Bill and other manufactures bother with posting here. But like you I thank them for their time and willingness to share the years of experience and knowledge with us.

Sparky

My idea of a fair fight is clubbing baby seals

[davidw 1]

John,
Thank you for posting John. You said, "The resere bag has been used for a lesser period of time, but no real problems". What do you mean by "...no real problems"?
Sincerely,
Racer 2K3 jumper

[skydiverek 55]

I don't think that you would be able to 'shake' the reserve out of Speebag in such low speed situation. Regular freebag seems to be better solution in such scenario:

http://www.youtube.com/watch?v=HpOCsQCKi7I

[JohnSherman 1]

Your posted video is a lot of ground - sky. There is no way to design for such a scenario. Except provide for a more positive cutaway. One anecdote does not a parameter for design make. Not that it shouldn’t be considered. The designer must consider the overall picture.

Did you know that there have been about 10 broken necks from Free bag deployments. They are very prone to line dump. The Velcro pouch will dump the lines at about 12 pounds. Only one of the safety stows has to release for the canopy to escape and because of the continuous nature of the safety stow, the off side stow looses all retention of its bight. All of this is unnoticeable at low speed cutaway, but when you get to higher speeds the principal falls apart. That 12 pounds to dump the lines is exceeded by about 10x and the low side stow is 5 pounds and the high side stow is also 12 pounds, you get a canopy right now! Before the lines extend. For those you believe every jump is a line dump I ask about the student at Sandwich who broke his neck on opening which killed him at the same time he broke his harness. I had a lawyer ask me to help him sue the harness maker. I told him the harness was OK while asking him what he thought broke the jumpers’ neck. That’s line dump, line strip, canopy dump, out of sequence deployment or whatever you want to call it. It’s all the same and must be avoided. The “Speed Bag” does that. It 100% prevents line dump and provides for a more orderly deployment, controlling the lines, accelerating the bag with each stow release to reduce overall “Snatch” and has been statically shown to reduce malfunctions from about 2 % to .03% at a sixth sigma level of confidence.

It actually takes no more effort to deploy a “Speed Bag” than it does a Free Bag. See the Videos in our gallery, It is the top one:
http://www.jumpshack.com/default.asp?CategoryID=Video%5FGallery

[skydiverek 55]

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Your posted video is a lot of ground - sky. There is no way to design for such a scenario. Except provide for a more positive cutaway. One anecdote does not a parameter for design make. Not that it shouldn’t be considered. The designer must consider the overall picture.

True. Makes sense, thanks for all the info!

[riggerrob 558]

Simplified answer: Safety-Stow works best at the low-speed edge of the envelope, while Speed-Bag works best near the high-speed edge of the envelope.

[KellyF 16]

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Simplified answer: Safety-Stow works best at the low-speed edge of the envelope, while Speed-Bag works best near the high-speed edge of the envelope.

But how big is the envelope? I've filmed traditional safety stow deployments at 240 knots with no hints of line dump or bag strip.

I may be repeating myself considering this thread is over 5 years old, so pardon the echo if I am

[JohnSherman 1]

Kelly,

At that speed 240KTs = 276MPH you would need to film at over 200FPS to even see it with the naked eye. The "Dynamis pressure" at that speed would be close to 200 Pounds per sq. foot. Line dump would occur in less than .1 seconds. So you might get 2 frames which had clues at to the actual event.
Didn't "Riggerlee" just say they were tearing up pilot chutes at half that pressure. What kind of aircraft did you do that out of. I want one.

John

[RiggerLee 61]

I'm not sure that you have to have a speed bag under most normal circumstances. But in the current project we're looking at useing our eight foot diamiter drouge to deploy our main. So on an adverage opening we're looking at a snatch force of 650 lbs. On an off nominal deployment we could be looking at two to four times that. That's a serious aceleration on the bag. And in the end I wound up building a speed/als bag. I blatently stole tecnologies from both manufactorers. And it packs up tight. Set 500 into a 13.5*8.5*9.25 bag. Normaly that would be like 16.5*8*10.5. When I say tight I mean I use temp pins and a tork bar to close the deployment bag. Don't get me started on what it takes to close the container. But the bottom line is the shit works. I've got film of it depoying at over 250 mph at about 750 lb snatch force based on the suspended weight. I think it's actually 5 frames to line streatch. But you can see it all. The risers lifting, 80 break cord snapping, lines unstowing and finally the slider at full line streatch. The Speed Bag works. Although to be fair it's got some ALS thrown in there to. Of course I had to "improve" on both designs. It's just my nature. Pause while misalanious vegtobles are thrown from the gallery. The point is that the speed bag works. It works where I doubt that any thing else ever could. No way would I trust a safety stow to withstand over 1500 lb of load but I'm putting my money on this speed bag design. or more percisly I'm betting about half a mill of my bosses money. You might also say that I'm betting my life on it as that is probable what I will be forfiting if I drop another one of there rockets.

Just to make it clear. I'm not a Sherman fan. I'm certinly not a racer fan. But the speed bag is an interesting idea. It has merrit. I'm not sure it's appopreit for a normal skydiver but it is doing good service in the envolope we are working in when I don't think any thing else could survive.

Lee

Lee
[email protected]
www.velocitysportswear.com

[skydiverek 55]

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I've got film of it depoying at over 250 mph at about 750 lb snatch force based on the suspended weight. I think it's actually 5 frames to line streatch. But you can see it all.

Can you post this video?

[KellyF 16]

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Kelly,

At that speed 240KTs = 276MPH you would need to film at over 200FPS to even see it with the naked eye. The "Dynamis pressure" at that speed would be close to 200 Pounds per sq. foot. Line dump would occur in less than .1 seconds. So you might get 2 frames which had clues at to the actual event.
Didn't "Riggerlee" just say they were tearing up pilot chutes at half that pressure. What kind of aircraft did you do that out of. I want one.

John

Again, I respectufully disagree. I was thinking it was about 6 frames to linestretch, Lee says about 5, but we're also talking different projects, so I'm in the ballpark. If it takes 6 frames of video for the bag to cover the ~10 feet of the length of the lines, and the lines come out of the pocket, you WILL see a wad of uncontrolled line somewhere between the bag and the container. True, you may not actually SEE the MOMENT the lines dump out of the pocket, but you'll know if it happened or not. These tests were done with 300+ sq.ft. canopies, maybe close to 400. I don't remember the details of the canopies.

One very interesting thing I DO remember that supports my point above is that the meshless PC's we were using had an interesting "failure". They would not start to pressurize until the bridle was loaded (naturally), but at the moment the bridle was loaded and the air entered the PC, the blast would hit the plate at the top of the spring, stretch the spring, then pop the tacks holding the plate to the spring, THEN the PC would fill and pressurize and lift the canopy out of the container. You could see it all frame by frame at 30fps. There was no damage to the PC canopy itself.

The plane was a B-25 and the drops were at 500'.

[RiggerLee 61]

Video is on a private FTP server. We've been through it frame by frame but it's kind of propriatary. There are contracts between various companies and all that lawyer shit. Not up to me. I'm hopeing they will make it public cause it's really cool. With luck we'll get a fully successfull flight here soon and they'll be crowing about it from the roof tops.

The pilot chutes we blew up were mesh pilot chutes with no "spring support". We started out with some old main pilotchutes left over from some old Talon student rigs. Cilindrical black springs. Used but in good shape. Then went to Tallon Stelth pilot chutes. Soon we moved to the final tube size which happioned to be perfect for the mini racer spring.

I was surprised when we blew all of them up. I didn't have numbers on exactly how fast they had been dropped in heavy/high speed phase of the TSO but I thought they would be able to come through with flying colors. In the end I concluded that they had survived because the canopies that they had been certified with had been squares. That it had just stripped the free bad off and was gone. My assumption. We had it fixed to the top of this 16 ft slider reefed round, small burble. We were dragging it through the air hard. Tore out the mesh, broke the tapes, blew out the fabric, streatched and mangaled the springs.

If the end I built some mini MA-1 style pilot chutes. They were smaller by design. Four gores. Made from some heavy nylon tafita that we had left over from a windblade project. I think it was a heave flag matearial, don't know I didn't buy it. I think I used 1/2 inch type 4 tape for the edges of the vaines/ radial seam tapes. It might have been 3/4. It did have a center conical section that suported/contained the spring. It really was a mini MA-1. I'm good at stealling tecnology. I don't recall ever seeing signs of load on the spring and I don't recall damage to the tacking. But I basically just built the systems and tested them. Fairly quickly others took over the droptest them selves. I came out from time to time but they did most of the packing and matonance them selves.

I'm not understanding how you were breaking your tacking? Did your "meshless" PC have a central cone like a MA-1? Do you think it was just an inerta thing where the weight of the spring tore it lose?

Lee

Lee
[email protected]
www.velocitysportswear.com

[JohnSherman 1]

I am looking forward to see the video but in the mean time I think I can explain our differences. We are comparing apples and oranges and pears.

Line dump, Bag strip, etc. (all the same thing) is not necessarily a bad thing, in and of itself. What does happen is when the bag opens and the slider is not constrained it can move down the lines, it will have a different reaction to different deployments methods depending upon the orientation to the relative wind.

There are Horizontal deployment and vertical deployment. There are two types of horizontal deployments, direct bag and ripcord activated. Verticals all work the same.

In a vertical deployment, when you dump the lines, the unconstrained slider will drop down the lines away from the canopy increasing the "Plate" inflation area. Depending on how far the slider migrates down the lines the opening shock will vary. The more migration, the harder the shock. This can and has broken necks in the most severe cases. At low speeds after a cutaway you will never notice it. However, anything from a streamer up can be problematic. The SPEED bag absolutely prevents this, but you could use a rubber band, which does nothing to discipline the deployment of the lines.

In a horizontal deployment, using a direct bag, the slider is blown down the lines during the deployment of the lines when the canopy is still attached to the bag and that big "C" occurs between the jumper, aft of and below the aircraft, and the canopy, still attached to the bag. During this moment the slider is exposed to a relative wind which blows it down the lines toward the jumper as the deploying canopy is actually upwind of the jumper. Hence the "Double Bag" with which the military is saddled. A SPEED Bag won’t help you much here except to keep the lines more orderly, but a rubber band could replace the “Double bag”

The Horizontal deployment with a pin pulling static line doesn’t experience the big "C", as the top of the canopy is not attached to the aircraft and a true horizontal deployment occurs. In this orientation the slider is resisted by the relative wind holding it in place during the early stages of the deployment awaiting its normal function and the jumper is correctly downwind of the deploying canopy. In this configuration line dump, even if it happened, would not be noticed as the controlling device, the slider, is functioning normally and has not been forced away from the canopy by the relative wind and in fact is held in place until the canopy begins to spread. Once again the SPEED bag isn’t needed to keep the canopy and slider contained as the relative wind does the job. However, a more orderly line deployment would be bonus.

I have found that the only way to define whether or not some high speed deployments were aberrant is to have instrumented the deployment and apply the “Stink Test” to the results. We know what a normal deployment graphic trace looks like and sampling at 500 times per second we can actually get a better picture than we can see on video at 30FPS. I have done a number of tests where they looked normal on video only to find aberration within the data. All this occurred before the SPEED bag was developed.

Additionally, this is why, in our “Owners Manual”, we recommend the center of the slider be held in place by a rubber band secured to the inboard “B” line on all ram air canopies in all situations.

[skydiverek 55]

What is a 'double bag'? How does it look and work?

[jonathan.newman 1]

The double bag is a static line deployment system that uses one bag to "direct bag" release a second system that contains a pilot chute, d-bag, and lines at full stretch. The inner bag is held closed by the pilot chute bridle. Once the pilot chute reaches full stretch, the inner bag opens and the canopy inflates. This prevents all the malfunctions caused by direct bagging a main while the lines get blown around while the jumper exits.

If you want to read more and see pictures, check out the SOV-3-HH manual here http://www.cpsworld.com/outside-pages/CPS-Technical-Manual.html

[JohnSherman 1]

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What is a 'double bag'? How does it look and work?

The canopy is packed into a deployment bag which has its own hand deploy type pilot chute. All of which is packed into a direct bag with static line attached to the aircraft. The direct bag uses the canopy lines to close the bag in the traditional way while the inside bag uses the pilot chute bridle to close the bag.
The idea is to deploy the second bag with the first bag, pushing the entire deployment downstream beyond the initial blast. It does take a bit more altitude but the slider comes down at the correct time.

[DSE 3]

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Kelly,

At that speed 240KTs = 276MPH you would need to film at over 200FPS to even see it with the naked eye. The "Dynamis pressure" at that speed would be close to 200 Pounds per sq. foot. Line dump would occur in less than .1 seconds. So you might get 2 frames which had clues at to the actual event.
Didn't "Riggerlee" just say they were tearing up pilot chutes at half that pressure. What kind of aircraft did you do that out of. I want one.

John

This is not correct. 60i may be on the fringe, but it does show ALL events occurring within that time frame and doubling/slowing frames does not reduce the information contained in those frames.