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adamUK

Opening shock forces

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Hello all,

I had a slammer a few months ago that left me bruised but not busted but it did leave me seeing stars. I also have followed the tandem fatality thread with interest ( http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=4330697;sb=post_latest_reply;so=ASC;forum_view=forum_view_collapsed;;page=unread#unread )

My question is: Does anyone have any data on the loads placed upon the body during opening and for a particularly hard opening what levels would cause serious injury or incapacitation? Has anyone measured these?

Many thanks in advance.


Adam.

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I had a whacker several years ago. The force caused my camera helmet to break through the fiberglass on both sides in the jaw area. My right foot hit my right shoulder and my neck broke into pieces.

I now have a neck made of part of my hip bone, a titanium plate, and a bunch of screws. I am partially paralyzed in my right hand and mostly paralyzed in my left hand and arm.

I’ve had whackers before, but this was an instant slammer!

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The force caused my camera helmet to break through the fiberglass on both sides in the jaw area. My right foot hit my right shoulder and my neck broke into pieces.

:oB|

Found some interesting information here though it refers to automotive and aeronautical fields primarily: ftp://ftp.rta.nato.int/PubFullText/RTO/EN/RTO-EN-HFM-113/EN-HFM-113-06.pdf

P.S. The severely injured data points are from tests using chimp and pigs. So not much different to skydivers then :P

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I got crushed a couple of weeks ago too. This is just an estimate but I'm pretty sure it was around 75 g's.



Death or serious injury can occur at 25 g's. If you had a ~75 g opening, you'd be lucky to be alive and able to move IMO.
"I may be a dirty pirate hooker...but I'm not about to go stand on the corner." iluvtofly
DPH -7, TDS 578, Muff 5153, SCR 14890
I'm an asshole, and I approve this message

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There is data and understanding about opening forces. It is a complex subject. You can find technical understanding in Theo Kanacke's "Recovery Systems Design Guide".

What you probably endured was Line Dump/Strip. This is when the lines are left in you container as the bag is lifted off. Caused by inadiquet line stows. The pilot chute generates about 20 G's as it jerks the bag out of the container. There is a great picture somewhere on this forum where the lines are 3 to 4 inches from the bottom of the bag during lift off. This demonstrates the differential of forces.
When this happens the slider drops down the lines before the lines are tight. Canopy inflates with full benifit of the slider. That is why I always rubber band my slider to the canopy.

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There is data and understanding about opening forces. It is a complex subject.



From what I read on the paper I found it was dependent on not only force magnitude and duration but also direction and the rate of increase of the force applied. I ended up with painful lower back, substantial bruise on my arm and my chin had also bruised my chest at the manubrium. I was lucky I guess considering some of the postings on here.

I discussed the incident with the rigger and it seems that a line dump was the most probable cause of the hard opening and it's something that I'll pay a lot more attention to in future. I'll look up the reference you supplied and thanks for the input. :)

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I got crushed a couple of weeks ago too. This is just an estimate but I'm pretty sure it was around 75 g's.



Death or serious injury can occur at 25 g's. If you had a ~75 g opening, you'd be lucky to be alive and able to move IMO.



Lollerskates!
Apex BASE
#1816

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I'm trying to recall but looking back I think I've been pressent for at least four fatalities that were the dirrect result of deceleration injuries. I've seen or have knowlage of other nonfatel injuries includeing one guy that would up a parapligic and another that wound up with a torn liver.

I'm not sure if any one has ever kept track of these especally the non fatel ones but it would be interesting. There's some pretty good data outr there on opening shock now. There's been a lot of work with data recorders and load cells. Ask Gary Peek. He was kind of leading the charge on that at one point.

Lee
Lee
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www.velocitysportswear.com

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How do you rubber band the slider to the canopy?
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There is data and understanding about opening forces. It is a complex subject. You can find technical understanding in Theo Kanacke's "Recovery Systems Design Guide".

What you probably endured was Line Dump/Strip. This is when the lines are left in you container as the bag is lifted off. Caused by inadiquet line stows. The pilot chute generates about 20 G's as it jerks the bag out of the container. There is a great picture somewhere on this forum where the lines are 3 to 4 inches from the bottom of the bag during lift off. This demonstrates the differential of forces.
When this happens the slider drops down the lines before the lines are tight. Canopy inflates with full benifit of the slider. That is why I always rubber band my slider to the canopy.


D-11672

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How do you rubber band the slider to the canopy?



IIRC the Vector tandem rig manual has a pretty good description.
"I may be a dirty pirate hooker...but I'm not about to go stand on the corner." iluvtofly
DPH -7, TDS 578, Muff 5153, SCR 14890
I'm an asshole, and I approve this message

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How do you rubber band the slider to the canopy?



IIRC the Vector tandem rig manual has a pretty good description.

Hmmm, I just looked at the Vector 2 Tandem Owners Manua;, 2003, p. 29, where packing the main is described and no mention is made of using a rubber band for the slider. Which Vector Tandem Manual do you have?
D-11672

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How do you rubber band the slider to the canopy?



IIRC the Vector tandem rig manual has a pretty good description.
Hmmm, I just looked at the Vector 2 Tandem Owners Manua;, 2003, p. 29, where packing the main is described and no mention is made of using a rubber band for the slider. Which Vector Tandem Manual do you have?



Oops, apparently I don't RC!:$

I'll look for where I saw it unless someone beats me to it.
"I may be a dirty pirate hooker...but I'm not about to go stand on the corner." iluvtofly
DPH -7, TDS 578, Muff 5153, SCR 14890
I'm an asshole, and I approve this message

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In 'g' terms (as in 2 g, 3 g), from what I've read, I don't think it makes much of a difference as the deceleration speed appears to be dependent on the mechanics of the canopy/container as it opens (any riggers able to shed any further light on this?). The speed of the jumper at the instant before deployment does make a difference though.

However with regard to the force applied on your body. The heavier you are the higher the force (i.e. 1.5g on a 200lb mass is 300 lb force whereas 1.5 g on a 100lb mass is a 150 lb force).

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