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NickDG

Ripcords for BASE jumps Was: Fatality - BASE jumper from Helicopter - Cinncinnati, Ohio - 08/22/2008

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I received an interesting PM this morning. It was from a Rigger, who in considering this incident and thinking out loud, wondered if we've considered going to ripcords and spring loaded pilot chutes for B.A.S.E. wingsuit flight.

It's not a new idea as I've thought about it before and talked to Todd at APEX about it in the past. And when thinking about pilot chute pouch location and extraction issues, it's the first thing a lot of older jumpers suggest.

Some of you may have also considered it too, and I'd like to hear your cons because I can't really think of too many.

One block may be more mental in the fact not many people have a great amount of experience with ripcords and spring loaded pilot chutes these days. And while the B.A.S.E. jumpers who skydive carry them around in their reserves it's not like they get used all that often.

On the pro side, the ripcord housing could be routed in all kinds of imaginative ways and the actual ripcord mounted anywhere. The housing could even be incorporated into the wingsuit itelf. And in reality you only have to pull a ripcord a couple of inches to get an open container.

The first downside would be what plagued spring loaded pilot chutes in the first place. Hesitations. But with the relative wind direction of wingsuit flight I don't see the pilot chute doing anything but being swept away. However, there probably is a small burble of dead air somewhere behind a wingsuit, so that's an issue. But the fix would be the same as it always was, just fold up. And if for any reason it did hesitate there could also be a chance for an out of sequence deployment. But that could be addressed by the design of the container.

And right before we went to hand deploy in skydiving we finally had some pretty decent spring loaded pilot chutes.

There was the Hot Dog pilot chute that was very tall and had a large spring that was easy to compress. And if you think about it, during full flight in a wingsuit, a pilot chute wouldn't need to jump up and out of the container as much as just stand up and be swept away.

Another concern with spring loaded pilot chutes would be limb entanglements. That happened back in the day sometimes. But again wingsuit airflow would keep it away from the arms, and since wingsuiters don't in effect have two naked legs trailing behind them it should be difficult for a problem there either. But I'm not sure if maybe a large spring loaded pilot chute could not somehow completely corkscrew around your lower body. But some airplane testing could sus that out.

Another stumbling block may be, and correct me if I'm wrong as I haven't been keeping up, is that some people design and build wingsuits, and some people design and build B.A.S.E. rigs. But is there a very experienced B.A.S.E. manufacturer that does both? Maybe we just need to get our ham and eggs together.

Again, like the Rigger who wrote me, this is just thinking out loud, but I wanted it on the record so if we do go in that direction, while you geniuses are patting yourselves on the back, some of us can say, hey, wait a minute! ;)

NickD :)

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I received an interesting PM this morning. It was from a Rigger, who in considering this incident and thinking out loud, wondered if we've considered going to ripcords and spring loaded pilot chutes for B.A.S.E. wingsuit flight.



Perhaps this side-thread would be better in gear and rigging, or BASE. In any event...

I'm no longer doing wing suit flight or BASE jumps, but my sense is that a wing suit flyer who is NOT traveling across the ground would have a tremendous burble. That probably isn't a problem for an aggressive flyer, but beginners might be placed in greater risk, and there may be times when an experienced flyer wants to deploy without horizontal speed. And I wonder what happens to the burble when the suit is stalled.

Just my thoughts.

Keep the discussion going. It's always worth reviewing what we have done when considering what we should do.
Tom Buchanan
Instructor Emeritus
Comm Pilot MSEL,G
Author: JUMP! Skydiving Made Fun and Easy

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I have a lot of experience with spring loaded pilot chutes and have also worked with a few other Gov't agencies to try and rectify Spring loaded pilot chute hesitation with military jumpers. This is based off real world issues where they are regularly encountered and we have tested different things in the wind tunnel as well as using Computational Fluid Dynamics programs to try and reduce or eliminate pilot chute hesitation. Without getting long winded, my take on this is that its not a good idea for the simple fact that if the PC bounces around even for a few seconds in the burble on a base jump someone is probably going to get hurt or die. I've seen PCs bounce in a jumpers burble on regular skydives long enough that the instructor had to move in and help it out of the burble. This happens enough in the skydiving environment that I think its a bad idea for the base environment. I think it would work but eventually there would be a hesitation, it's inevitable.
"It's just skydiving..additional drama is not required"
Some people dream about flying, I live my dream
SKYMONKEY PUBLISHING

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Is there a significant difference between a spring-loaded main pilot chute and a spring-loaded reserve pilot chute? The kinds of hesitation you're describing seem like they'd result in some nasty situations on a reserve. Is it simply that reserves are generally deployed in nonstandard body positions? In other words, would a stable reserve deployment potentially result in the same kinds of hesitations that you're describing on main pilot chutes?
I really don't know what I'm talking about.

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But is there a very experienced B.A.S.E. manufacturer that does both? Maybe we just need to get our ham and eggs together.



nick rugai he has a base wingsuit/container setup already...
Leroy


..I knew I was an unwanted baby when I saw my bath toys were a toaster and a radio...

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Is there a significant difference between a spring-loaded main pilot chute and a spring-loaded reserve pilot chute? The kinds of hesitation you're describing seem like they'd result in some nasty situations on a reserve.



That can vary from mfgr to mfgr on sports rigs (Mirage has a 55lb spring if I remember correctly,other mfgrs less). Part of the problem is where the main PC is deploying from on the back of the jumper and if the PC has shifted any in the pack tray(they all do to some extent). Reserve PCs launch from higher up on the back where there is still a decent airflow and they are usually seated through the center of the cap so that they cannot and do not shift or move around because the reserve closing loop keeps them in place. The arm wings and tail wing on a wingsuit roughly have a similar sized burble as a military jumper with a rucksack and equipment on. Based on what has been observed with PC hesitations on military jumpers, it is not too far a stretch to see that the same could potentially happen with a wingsuit. You could potentially have a PC fire back into the jumpers tail wing and hesitate and or bounce around a bit. Granted this can be for as short as a few seconds (or longer) but in a base environment that is way too long sometimes.
"It's just skydiving..additional drama is not required"
Some people dream about flying, I live my dream
SKYMONKEY PUBLISHING

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I've semi-jokingly said for years that the low pull wingsuit guys need to have belly mounted srping loaded pilot chutes activated with a thumb switch of some sort. They would get a clean launch and never have to collapse the wings:)

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>In other words, would a stable reserve deployment potentially result in the
>same kinds of hesitations that you're describing on main pilot chutes?

Yes. In fact, some manufacturers (Jump Shack) specifically recommend that you deploy your reserve head-high to minimize hesitations. Fortunately this is the position you are in immediately after a cutaway - which is why "cut away and get stable" can be a bad idea.

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I've semi-jokingly said for years that the low pull wingsuit guys need to have belly mounted srping loaded pilot chutes activated with a thumb switch of some sort. They would get a clean launch and never have to collapse the wings:)



Balistic reserve?
"The restraining order says you're only allowed to touch me in freefall"
=P

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Agreed, circa 1993, Troy Loney (R.I.P.) gave a seminar (at a PIA Symposium) about test dropping EOS reserve containers. He concluded that the best time to launch a reserve pilot chute was one second after cutaway, coincidentally at the same time that RSLs release pilot chutes.
The key was air flowing UP the back, to quickly blow the pilot chute off the skydiver's back.
Since EOS prototypes had weak springs, we learned a lot about weak pilot chute launches.
If test jumpers hesitated two or three seconds, an EOS pilot chute could hesitate for five or more seconds (fatal to BASE jumpers) before total velocity increased to enough to suck a pilot chute off his back.
EOS production pilot chutes had much stronger springs that could launch them farther than most burbles.
Similarly, a BASE jumper would be best off deploying a spring-loaded pilot chute while still in forward flight, This would minimize the thickness of the burble over his back.
However, you cannot trust junior BASE jumpers to do the right thing, so we have to re-think the whole idiot-proofing concept ...

For BASE/wingsuit, I was thinking more in terms of a spring-loaded pilot chute attached to the left ankle, to ensure smooth, vigorous airflow and little chance of entanglement with legs.

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Interesting thread!

With regard to the problems of springloaded PC's hesitating, it seems like the same rules would apply as do to the throw-out PC. BASE PC's are much, much larger than skydiving PC's, and often significantly larger than skydiving reserve PC's. Springloaded PC's for BASE would logically also be quite large, and therefore less likley to hesitate.

A very strong spring would also seem obvious, and with a fairly large diameter to help prevent the PC from launching sideways. If I were a BASE jumper, I'd be much more inclined to use a spring similar to a vector (fairly strong and wide) than that of a dolphin (wide but weak) or a wings (strong but skinny).

One disadvantage is that beginning BASE jumpers who may hold the PC during the "exit" would require a different PC, as well as a different way to close the container. Since I am not a BASE jumper, I'm not sure how often this is really done... I'm sure among the experienced BASE community it's uncommon. As a corollary, it would be a disadvantage if the springloaded PC was intended for wingsuit BASE only and not standard BASE, as seems to have been suggested by the OP.
"Some people follow their dreams, others hunt them down and beat them mercilessly into submission."

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>A very strong spring would also seem obvious . . .

I'm thinking we should get away from springs in the PC. They are the cause of a lot of the problems with ripcords - the PC starts bouncing around, has more inertia etc.

Instead, leave the spring in the rig. Have the PC launched by the spring (which will either launch it with great force upwards or, worst case, simply present it to the wind 2 feet above someone's back.) Nothing heavy to interfere with deployment. Cover the spring with mesh so it's not a snag hazard and have it attached to the dbag or topskin. If you attach it to the dbag near the bridle the dbag will tend to "collapse" it in actual usage.

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>A very strong spring would also seem obvious . . .

I'm thinking we should get away from springs in the PC. They are the cause of a lot of the problems with ripcords - the PC starts bouncing around, has more inertia etc.

Instead, leave the spring in the rig. Have the PC launched by the spring (which will either launch it with great force upwards or, worst case, simply present it to the wind 2 feet above someone's back.) Nothing heavy to interfere with deployment. Cover the spring with mesh so it's not a snag hazard and have it attached to the dbag or topskin. If you attach it to the dbag near the bridle the dbag will tend to "collapse" it in actual usage.




We tested a similar concept to what you just described, the device was at the Reno PIA on display in fact. It looked good in design and it did very well when we tested it in the wind tunnel but when we tested it out in the sky it was actually worse than a standard spring PC and some of the test jumpers almost had terminal reserve rides and or entanglements. Needless to say that idea/design was not as good as it appeared to be when put into use for real.
"It's just skydiving..additional drama is not required"
Some people dream about flying, I live my dream
SKYMONKEY PUBLISHING

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Don't know if anybody has thought about this design already, and I'm sure they have.

The main reason for PC hesitation with a spring loaded, is because of the burble on the jumper's back. A throw out obviously is not affected by this, as it's being thrown out to the side of the jumper. By the time it's above the jumper's back, it's already past the burble.

What if you could develop a system, that has a ripcord, but that leads to a PC on the lower right of the container, at about a 45 degree angle. This could be a spring loaded chute as well. That way, when the ripcord is pulled, the pilot chute takes off to the side of the jumper, and enters the air the same way as a throw out. The only modification would be a small bridle routing, from the PC, to the D-Bag, which would still be in the same location, bottom center.

Just an idea.
Skydiving: You either learn from other's mistakes, or they'll learn from yours.

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They had skydiving rigs in the 70s that were spring loaded and side deployed just as you described.

But I'm off the spring loaded PCs now and onto something else. If you want you can read about it in this thread:

http://www.basejumper.com/cgi-bin/forum/gforum.cgi?post=1294243;sb=post_latest_reply;so=ASC;forum_view=forum_view_collapsed;;page=unread#unread

NickD :)

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How about spring-loaded PC mounted on a side of the wingsuiter's leg, so it launches away from the burble, not into it? If it can launch 3-4ft to the side, it's in completely clean air.

If you saw that video with a jumper jumping a skydiving container with only a reserve in it, off that famous NorCal A (if not first, surely one of the few jumps of this kind), what do we see happening on pull? A big, classic spring-loaded PC bounce in the burble...
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The only modification would be a small bridle routing, from the PC, to the D-Bag, which would still be in the same location, bottom center.



Others have thought of that very same idea and it sounds good until you try and design it for real. For starters, you would need a pin to close the main container and a pin to close the spring PC mini container on the side of the container.

When you look at any container and attempt to find a place for the spring PC to be mounted to, you will find that most of the surfaces are either tapered or rounded and are smaller than the diameter of the spring PC. One of the contributing factors to PC hesitation that was discovered during the testing we did was that a poor or uneven launch platform can cause a weak launch. Normally the PC is packed directly on top of the D bag which is not a very solid or stable platform as it can and does compress. So what happens when the container opens is the springs energy is transfered in two directions simultaneously and you get a weak launch. One of the ways to improve PC launch is to install what is known as a kicker plate on the D bag or an inner flap thats under the last flap closed on the container. The later is a major pain in the ass to pack as we only have 2 hands and you really need 3 to keep from eating spring loaded PC. So besides finding and area large enough for the PC on the side of the container, it would also need a kicker plate.

Hopefully you are beginning to see how Frankenstein and complicated something like this would look. Then you still have issues like a ripcord cable housing that has to accommodate the exit of a 2 pin ripcord that has about 12-18 inches of cable between the pins that has a pull direction thats on an angle. I could keep going but I won't. It's a good idea but it's hard to implement without creating new problems.

All I can say is that this topic has been looked at pretty hard by some very smart people, but if anyone can develop a system that actually works without creating new issues, I know some people who will buy them.:D
"It's just skydiving..additional drama is not required"
Some people dream about flying, I live my dream
SKYMONKEY PUBLISHING

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One disadvantage is that beginning BASE jumpers who may hold the PC during the "exit" would require a different PC,



:D

Someone who uses the same PC for terminal wingsuiting as they do for handheld go and throws has gone pretty wrong as it is!
Do you want to have an ideagasm?

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That can vary from mfgr to mfgr on sports rigs (Mirage has a 55lb spring...



Yeah, those friggin' Mirage reserve pilot chutes springs don't really "launch" the reserve pilot cute & bridle when activated. What they really do is jettison the rig and wearer in the opposite direction, thus getting the reserve pilot cute into clear air. :D


Anyway, as for ballisticly fired reserves... I'm surprised that some of these slope soaring-bird-suit BASE types haven't hit on that yet! :S

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We thought of that in the early days of B.A.S.E. when ballistic deployed reserves first appeared.

If you jumped from a building and had a 180 opening instead of trying to turn around you'd upholster your "pistol" and fire it over you shoulder. And besides B.A.S.E. jumpers standing in front of mirrors practicing their quick draw, "Hey 180, you talking to me?" There would be this eventuality:

#330, October 14, 2010
Dwight Burp
Los Angeles, CA, USA
Building Jump
Impact
In preparation for their building launch two jumpers were doing gear checks when Dwight accidentally hit the button on his partners ballistic deployed reserve. The resulting deployment hit Dwight square in the forehead and killed him.

NickD :)

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Doesn't base jumping have it's own web site?
Do you not have a gear thread of some sort?

I don't mean to stir you guys up, I totally get what base is all about and I get why people dig it so much....but why are we discussing base gear on a skydiving web site??:S

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