Forums: Skydiving: Incidents:
8 May 2013 Fatality Skydive Deland

 


captain1976  (D 7183)

May 8, 2013, 4:03 PM
Post #1 of 161 (6801 views)
Shortcut
8 May 2013 Fatality Skydive Deland Can't Post

Lost a good friend this afternoon. Highly experienced Jumper who opened lower than he usually did and had a turning line-over type malfunction.

Rode it til about 400 ft for some reason then chopped it. Reserve didn't have time to inflate and reports from eye witnesses said it was a slow turning "bow tie" type malfunction. He jumped a fairly large canopy (I think a 210 or 220). Blue Skies Sandy


ReluctantStool  (A 65507)

May 8, 2013, 4:43 PM
Post #2 of 161 (6678 views)
Shortcut
Re: [captain1976] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Frown Sad news for sure. Frown


captain1976  (D 7183)

May 8, 2013, 4:58 PM
Post #3 of 161 (6633 views)
Shortcut
Re: [captain1976] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

A most recent report from a witness I spoke with stated he may have had trouble finding the handle given his baggy jumpsuit and new rig.

Further reported is the reserve did actually inflate at time of impact and he could have used a few extra feet of sky.

Been a while since I lost someone I know to our sport. Lots in the old days but that's when parachutes didn't open and being older I don't know that many swoopers who seem to buy it with more regularity.

I share with others how hard it is to make these reports of those we know Frown

http://www.news-journalonline.com/...ailure-official-says


(This post was edited by captain1976 on May 8, 2013, 6:46 PM)




phreeloader  (Student)

May 8, 2013, 6:58 PM
Post #5 of 161 (6315 views)
Shortcut
Re: 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

So sorry for your loss, I jump at Deland on occasion but i don't believe I ever had the pleasure of meeting Sandy

Do you know if he had an RSL? or do you believe it was the cut away handle he had a hard time finding


(This post was edited by phreeloader on May 8, 2013, 6:59 PM)


captain1976  (D 7183)

May 8, 2013, 7:11 PM
Post #6 of 161 (6284 views)
Shortcut
Re: [phreeloader] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

phreeloader wrote:
So sorry for your loss, I jump at Deland on occasion but i don't believe I ever had the pleasure of meeting Sandy

Do you know if he had an RSL? or do you believe it was the cut away handle he had a hard time finding

I don't remember if he had an RSL or not but I would guess yes. I will find out though and report. I just wanted to convey that he "might" have had a hard time finding the handle.


Divinfool  (C 40922)

May 9, 2013, 4:29 AM
Post #7 of 161 (5737 views)
Shortcut
Re: [captain1976] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Such a loss. I believe he had an RSL.... He was cool under pressure. I was with him on his first chop and remember him saying..."No big deal..just followed my EP's". Can't believe he did not pull this one out. Frown
He seldom packed his own rig... his main was relatively new... a 150 Apache. He told me a few times that it could get radical if he got into a spin.


(This post was edited by Divinfool on May 9, 2013, 7:22 AM)


IronEddie42  (D 32850)

May 9, 2013, 5:53 AM
Post #8 of 161 (5597 views)
Shortcut
Re: [captain1976] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

He was a very close friend of mine, and I was there and watched the entire thing unfold right in front of me. In fact, I missed being on the load by about 5 minutes.

He did indeed have a classic "bow tie" line over malfunction after opening lower than he usually does (I would estimate somewhere between 2000-2500' or so. He ended up spinning rather quickly under the malfunction and for some reason or another, didn't cut away until approximately 300', at which point, his reserve came out but did not inflate entirely before he hit the ground.

His main was an Apache 150, but I do not know what his reserve size was. It was in a Mirage G4 container, so no Skyhook - just a standard RSL.


parkair  (D 33246)

May 9, 2013, 7:06 AM
Post #9 of 161 (5476 views)
Shortcut
Re: [IronEddie42] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Thanks for the update Steve! Don't understand why he took so long to react either. Wasn't like him at all. I hope we find some answers to help understand and learn from this. However, violent spins are difficult to handle in short order.


Divinfool  (C 40922)

May 9, 2013, 7:23 AM
Post #10 of 161 (5435 views)
Shortcut
Re: [parkair] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Ditto, thanks for the update Steve.


(This post was edited by Divinfool on May 9, 2013, 7:26 AM)


kruse  (D 11173)

May 9, 2013, 8:43 AM
Post #11 of 161 (5298 views)
Shortcut
Re: [IronEddie42] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Did anyone find his cutaway handle? Maybe the cables needed cleaning and/or lubing?


IronEddie42  (D 32850)

May 9, 2013, 8:44 AM
Post #12 of 161 (5292 views)
Shortcut
Re: [kruse] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

kruse wrote:
Did anyone find his cutaway handle? Maybe the cables needed cleaning and/or lubing?
I spoke to one of the first people on scene and he confirmed that both handles were manually pulled, so it's possible, but unlikely.


kruse  (D 11173)

May 9, 2013, 8:51 AM
Post #13 of 161 (5273 views)
Shortcut
Re: [IronEddie42] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

A hard pull on the cutaway handle may indeed explain a low rsl deployed reserve. Again,....did anyone find the cutaway handle?


IronEddie42  (D 32850)

May 9, 2013, 9:50 AM
Post #14 of 161 (5151 views)
Shortcut
Re: [kruse] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

kruse wrote:
A hard pull on the cutaway handle may indeed explain a low rsl deployed reserve. Again,....did anyone find the cutaway handle?
This is true, however, his RSL was found disconnected. So maybe he was thinking that because he was under a spinning malfunction that he needed to disconnect his RSL and that could explain the hesitation going to his reserve.

At this point, all we're left with is unanswered questions, and that's definitely the hardest part of all of it.


-ftp-

May 9, 2013, 10:33 AM
Post #15 of 161 (5065 views)
Shortcut
Re: [captain1976] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

was he possibly knocked out? To make the decision to cutaway that low no matter if you have a skyhook or not would not be a good decision. Do you think he came to and just reacted? Surely just going straight to reserve at that altitude would have been a better bet. Sorry for your loss.


captain1976  (D 7183)

May 9, 2013, 11:55 AM
Post #16 of 161 (4903 views)
Shortcut
Re: [IronEddie42] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

IronEddie42 wrote:
kruse wrote:
A hard pull on the cutaway handle may indeed explain a low rsl deployed reserve. Again,....did anyone find the cutaway handle?
This is true, however, his RSL was found disconnected. So maybe he was thinking that because he was under a spinning malfunction that he needed to disconnect his RSL and that could explain the hesitation going to his reserve.

At this point, all we're left with is unanswered questions, and that's definitely the hardest part of all of it.

Trying to disconnect an RSL may very well have been an issue. If you look at the attached pix of him with his rig you will see his rings and rsl a bit higher than I like them.
Attachments: sandy.jpg (72.6 KB)


Divalent  (C 40494)

May 9, 2013, 12:10 PM
Post #17 of 161 (4876 views)
Shortcut
Re: [IronEddie42] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Looks like he was in the sport just a bit less than two years. Any idea how many jumps he had, and whether he had had cutaways in the past? Also, do you know what his approximate wing loading was?


IronEddie42  (D 32850)

May 9, 2013, 12:23 PM
Post #18 of 161 (4855 views)
Shortcut
Re: [Divalent] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Divalent wrote:
Looks like he was in the sport just a bit less than two years. Any idea how many jumps he had, and whether he had had cutaways in the past? Also, do you know what his approximate wing loading was?
I believe he had between 400-500 jumps, maybe slightly more.

I believe this was his first malfunction/cutaway, but not positive.

Wingloading was approximately 1.4:1 or so, but that's mostly a guess.


cwniles

May 9, 2013, 12:32 PM
Post #19 of 161 (4828 views)
Shortcut
Re: [IronEddie42] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

just to clarify...

Divinfool wrote:
I was with him on his first chop and remember him saying..."No big deal..just followed my EP's". Can't believe he did not pull this one out. Frown


sundevil777  (D License)

May 9, 2013, 12:36 PM
Post #20 of 161 (4816 views)
Shortcut
Re: [captain1976] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

If he had difficulty cutting away, perhaps the mini 3 rings contributed to that. I don't like them at all, especially for heavier jumpers.


Divinfool  (C 40922)

May 9, 2013, 12:39 PM
Post #21 of 161 (4808 views)
Shortcut
Re: [cwniles] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

His first chop was around 180 jumps. He told me "it was really uneventful". He was a level headed pilot that I am sure was used to dealing with emergencies. Can't imagine he was knocked out. Like Steve said... these are questions we may never know.


dqpacker  (D 32043)

May 9, 2013, 12:48 PM
Post #22 of 161 (4792 views)
Shortcut
Re: [sundevil777] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

sundevil777 wrote:
If he had difficulty cutting away, perhaps the mini 3 rings contributed to that. I don't like them at all, especially for heavier jumpers.

i've chopped 5 times with mini 3rings on highly loaded canopies spinning, and never had a problem, and i'm a bigger dude.
what might have been a real contributor to a hard cutaway is if he had hard housings in his risers.
but if his rsl was disconnected, my guess is he took too much time disconnecting it, instead of just cutting away.


phreeloader  (Student)

May 9, 2013, 12:52 PM
Post #23 of 161 (4780 views)
Shortcut
Re: [Divinfool] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Divinfool wrote:
Like Steve said... these are questions we may never know.

Anyone know if he was wearing a camera?


IronEddie42  (D 32850)

May 9, 2013, 1:13 PM
Post #24 of 161 (4744 views)
Shortcut
Re: [phreeloader] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

phreeloader wrote:
Divinfool wrote:
Like Steve said... these are questions we may never know.

Anyone know if he was wearing a camera?
He was, but I'm sure we'll never see the video.


Premier Remster  (C License)

May 9, 2013, 4:16 PM
Post #25 of 161 (4488 views)
Shortcut
Re: [dqpacker] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

If this is what happened... Sigh. When did disconnecting an rsl become part of emergency procedures?

People: don't start rigging during a map.




Tetrahedron

May 9, 2013, 7:54 PM
Post #27 of 161 (2325 views)
Shortcut
Post deleted by Tetrahedron [In reply to]

 


ryoder  (D 6663)

May 9, 2013, 8:12 PM
Post #28 of 161 (2303 views)
Shortcut
Re: [Tetrahedron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Tetrahedron wrote:
Cutting away from a spinning malfunction with an RSL gives you a good chance of winding up with numerous line twists on your reserve.
It's actually a good decision to disconnect the RSL before cutting away, in that situation, but not if it takes you more than 5 seconds to disconnect it.

The moment you cutaway, you fly away from the canopy feet-first in a straight line. The relative wind is blowing from your feet toward your head.

You can simulate this by tying a weight to the end of a cord, then spinning it overhead and letting it go. The spin ends the moment it is released.


davelepka  (D 21448)

May 9, 2013, 8:16 PM
Post #29 of 161 (2300 views)
Shortcut
Re: [Tetrahedron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Quote:
Cutting away from a spinning malfunction with an RSL gives you a good chance of winding up with numerous line twists on your reserve.
It's actually a good decision to disconnect the RSL before cutting away, in that situation, but not if it takes you more than 5 seconds to disconnect it.

That's some of the worst advice I've heard. If you jump an RSL, leave it hooked up unless you plan to land in water or on top of a building.

Taking 5 seconds while spinning (and diving) toward the ground to disconnect an RSL is a huge waste of time you probably don't have. What are you going to do next? Spend time trying to get stable before pulling your reserve handle?

That's bullshit. You're spinning because the canopy is turning. Your body is not spinning relative to your own centerline, the canopy is spinning relative to it's own cneterline. If you cutaway, you will get flung off to the side in a straight line. The RSL will actually help you by getting the reserve extraction started immediately, before you have a chance to fuck the whole thing up and flip yourself ass over teakettle.

You're giving out very poor advice, and if you plan to follow that same advive, you're setting yourself up the same thing that happened here. If you're not preparred to have an RSL assisted reserve deployment on any cutaway you might have, then do not jump an RSL. There is no time or place for reconfiguring your rig in the middle of a malfunction.


popsjumper  (D 999999999)

May 9, 2013, 8:30 PM
Post #30 of 161 (2291 views)
Shortcut
Re: [Tetrahedron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

In reply to:
Cutting away from a spinning malfunction with an RSL gives you a good chance of....

You may want to re-think that and cease offering incorrect advice to others. Somebody told you wrong or you just don't know what you don't know.


Tetrahedron

May 9, 2013, 11:10 PM
Post #31 of 161 (2206 views)
Shortcut
Re: [popsjumper] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

popsjumper wrote:
In reply to:
Cutting away from a spinning malfunction with an RSL gives you a good chance of....

You may want to re-think that and cease offering incorrect advice to others. Somebody told you wrong or you just don't know what you don't know.

What would you say the reason is that most skydivers prefer to not use an RSL?

I forgot this forum is ruled by dinosaurs.

I'll leave you all to it. Bye.


phreeloader  (Student)

May 9, 2013, 11:14 PM
Post #32 of 161 (2204 views)
Shortcut
Re: May 2013 Fatality Skydive Deland [In reply to] Can't Post

 

...So is this just bad reporting? or is there more to this?

http://www.news-journalonline.com/...509743?p=1&tc=pg


Quote:
Spence told police there were no issues when they broke away at 4,000 feet, and he saw Rosell's open chute, which he believed was working properly, at 3,000 feet.

Richard Ford, Rosell's other co-sky diver, also told police he saw Rosell deploy his parachute but he wasn't able to clearly see the landing Rosell made because he was still too high up, according to the report. He said he thought he saw Rosell's original chute cut away and land in some woods. However, a New Smyrna Beach man, Trevor Cedar, later showed up at the scene of the tragic fall and reported the cut-away chute was his and had nothing to do with Rosell's fatal fall, according to the report.

Skydive DeLand's general manager, Mike Johnston, said it's his understanding that Rosell's chute did open but there was a controllability problem with it.

He elected to release it, which we call cutting it away, and use his emergency procedures, Johnston said.


davelepka  (D 21448)

May 10, 2013, 4:22 AM
Post #33 of 161 (2082 views)
Shortcut
Re: [Tetrahedron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Quote:
What would you say the reason is that most skydivers prefer to not use an RSL?

I would guess ignorance. When you say 'most' skydivers, do you mean most the skydivers who don't use an RSL, or are you suggesting that 'most' jumpers overall do not use an RSL. By my casual observation, more jumpers than not are using an RSL.

In any case, your suggestion that a spinning mal makes you as an individual spin remains incorrect. Relative to your canopy, you are not spinning, you are hanging in a fairly static position under your wing. The canopy itself is turning, but that has nothing to do with you personally. Your body, in relation to itself, has no rotational momentum to speak of.

Sit down and do some hard thinking on the physics of the situation, and you'll see that you're getting yourself all mixed up as to which forces are being applied to which object.

Quote:
I forgot this forum is ruled by dinosaurs.

Food for thought, your ideas about RSLs and malfunctions came from one of two places - either another 'dinosaur' (aka, high-time jumper) told you this, and in that case you hitched your wagon to a dinosaur (which in this case was a mistake). The other possibility is that you came up with this on your own, or you heard from another non-dinosaur, and now you're hearing otherwise some actual dinosaurs.

The point is that the reason I'm a 'dinosaur' is that I've managed to survive long enough in this sport that my USPA card can vote or go to war. If you think I've spent that time flying a 220 and doing 3-way RW, think again.

With that in mind, and the idea that there are literally 1000's of other jumpers reading these boards (a good number of which seem to love to prove me wrong), I would suggest that the advice I'm giving is legit. What you head from one guy or made up yourself is one thing, what I suggest to you here that's being read and not immediately shot-down for being even the slightest bit 'off' is another, and it's probably what you want to go with.


(This post was edited by davelepka on May 10, 2013, 4:22 AM)


potatoman  (Student)

May 10, 2013, 5:02 AM
Post #34 of 161 (2045 views)
Shortcut
Re: [davelepka] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Back to the topic.

Did the jumper attempt to clear line in some way, or tried to fly the bowtie? Would probably be visible from the main if the slider toggles was done/undone.

As the witnisses said, he did the cutaway close to the ground, so one would easily be able to see if his hands were UP or on the EP handles.


pchapman  (D 1014)

May 10, 2013, 5:42 AM
Post #35 of 161 (2006 views)
Shortcut
Re: [davelepka] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

I'm going to put a different spin on things so to speak.

If you are rotating under the mal, you will rotate when you cutaway. You do have rotational momentum, that will rotate you as you chop. You may be spinning or rolling when you chop, and will continue to do so for some time after the chop -- while the RSL is activating the reserve.

Consider a simplified model spiral dive, just an object at the end of a string spun in a horizontal circle, and ignore the descent rate. When the object released from the string it does go straight out on a tangent to the circle.

But if the object, the jumper, were spinning around once every two seconds, the jumper would be rotating around his own belly 180 degrees a second, even when he is also moving around in a circle at the same time.

When he gets flung off at the moment of cutaway, he'll still be rotating 180 degrees a second, while flying off straight at a tangent to the circle.

So the RSL is starting to extract the reserve while the jumper is spinning. Although at least in this case, the jumper remains belly to earth.


You also get mals where the canopy is more overhead and the jumper is spinning around underneath, more of a 'helicopter' type thing.

The resolution is crappy, but an example is this video from when I deliberately cut away one riser only in an intentional cutaway: http://blip.tv/...ide-at-a-time-242566 While it is an artificial mal, I have seen high performance canopy mals that are like that.

The jumper (me) has lots of rotational momentum, 360 degrees a second in the video, and obviously continues to spin like that after the cutaway, with speed slowing over a few seconds due to drag and hopefully no pro-spin inputs any more.

I would sure not like to have an RSL pop the reserve when spinning like that on my back!

If I were caught really low, I'd still be grateful for an RSL -- but I'm not going to pretend the RSL would magically provide a clean reserve extraction relative to my body.


Let's now expand the first example, going back to the 'spinning in a circle' case: There the jumper is rotating only around his belly to back axis. Now make it more complex and realistic by turning the motion into a descending spiral like many mals. For the jumper to follow the canopy motions, you can see that the jumper is also rotating on his head to toe axis -- he is rolling.

At the extremes, he's not rolling at all if just spun in a circle with no descent like the first example, and rolling as fast as the canopy is turning in the second 'helicopter' example with a spinning canopy right above. So for a spiral dive, that is somewhere between these two simplified types of motion, the rolling speed of the jumper will be somewhat in between.

Still the jumper is rolling.

So when he cuts away, in addition to the spinning motion around the belly to back axis, superimposed on that is also some rolling motion depending on the nature of the malfunction. He's rolling and spinning after he jettisons his main!


Additionally, there are other complications to the direction the reserve pilot chute will go. Not just in my 'helicopter' example, but in other spiralling mals, the jumper is sometimes on his back, so his back is to the relative wind. So whatever you think about "rotating after chopping", you still expect him to have his reserve bridle going up around his shoulder when the RSL activates his reserve.

RSL's do work but they do not always provide the nice direction of reserve extraction that many like to think.


IronEddie42  (D 32850)

May 10, 2013, 5:45 AM
Post #36 of 161 (1997 views)
Shortcut
Re: [phreeloader] May 2013 Fatality Skydive Deland [In reply to] Can't Post

phreeloader wrote:

...So is this just bad reporting? or is there more to this?

http://www.news-journalonline.com/...509743?p=1&tc=pg


Quote:
Spence told police there were no issues when they broke away at 4,000 feet, and he saw Rosell's open chute, which he believed was working properly, at 3,000 feet.

Richard Ford, Rosell's other co-sky diver, also told police he saw Rosell deploy his parachute but he wasn't able to clearly see the landing Rosell made because he was still too high up, according to the report. He said he thought he saw Rosell's original chute cut away and land in some woods. However, a New Smyrna Beach man, Trevor Cedar, later showed up at the scene of the tragic fall and reported the cut-away chute was his and had nothing to do with Rosell's fatal fall, according to the report.

Skydive DeLand's general manager, Mike Johnston, said it's his understanding that Rosell's chute did open but there was a controllability problem with it.

He elected to release it, which we call cutting it away, and use his emergency procedures, Johnston said.

There was another incident on the same load - Trevor and a young jumper had a canopy collision just after opening - Trevor had to cut away, the other jumper did not.


Premier wmw999  (D 6296)

May 10, 2013, 5:53 AM
Post #37 of 161 (1987 views)
Shortcut
Re: [pchapman] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

I've had a couple of spinning mals on a Diablo -- they spin pretty good, and in both cased my RSL activated my reserve with neither incident nor line twists.

If you're thrown away from your spinning main, the rotation that was happening around your main is going to stop, because the fulcrum (the main) is gone. If you were also twisting (i.e. either the spinning line twists were twisting up worse or untwisting) that component can stay with you I believe.

Wendy P.


ufk22  (D 16168)

May 10, 2013, 6:10 AM
Post #38 of 161 (1966 views)
Shortcut
Re: [Tetrahedron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Giving you your point (not that I agree) would you rather have an inflated reserve with line twists at 300' or a partially inflated reserve at impact??????????


ryoder  (D 6663)

May 10, 2013, 6:32 AM
Post #39 of 161 (1933 views)
Shortcut
Re: [wmw999] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

wmw999 wrote:
I've had a couple of spinning mals on a Diablo -- they spin pretty good, and in both cased my RSL activated my reserve with neither incident nor line twists.

If you're thrown away from your spinning main, the rotation that was happening around your main is going to stop, because the fulcrum (the main) is gone. If you were also twisting (i.e. either the spinning line twists were twisting up worse or untwisting) that component can stay with you I believe.

Wendy P.

Wendy is absolutely correct. I have also chopped a spinning Diablo. I was on my back, facing the sky, watching the horizon rushing by my feet in a blur. I put one hand on the cutaway, one hand on the reserve, chopped, pulled, and saw the horizon immediately stabilize as I got a clean, on-heading reserve opening.

The flying world has the myth of the "downwind turn", and skydivers have the myth of the spin that remains after the cutaway.Crazy


davelepka  (D 21448)

May 10, 2013, 6:48 AM
Post #40 of 161 (1917 views)
Shortcut
Re: [pchapman] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

 
I'll admit that there are some very specific circumstance where a jumper could have some 'personal' rotational momentum built up that could remain after the chop. That said, I have never heard of a jumper who got wrapped up in a reserve bridle or lineset, the worst I've heard of line twists. To that end, I've also heard of line twists on an otherwise 'clean' cutaway and reserve deployment.

Those very specific circumstance would certainly be some of the most violent, disorienting and high-speed malfunctions, making it the worst possible time to be concerned with trying to disconnect an RSL, and then playing the losing game of trying to get stable before pulling your own reserve.

I maintain that the best course of action in such circumstances would be an immediate cutaway and reserve deployment. Less altitude loss, less disorientation and more time to kick out of any reserve line twists if they should occur.

Let's remember that a malfunction only occurs after you have decided it was time to end the skydive. Your main might have different ideas, but in any case you're going much faster than you wanted to be at the given altitude. Staying on track, and slowing yourself way down should be your #1 priority, and analyzing the nature of your mal and reconfiguring your rig to match is not conducive to stopping anything.

If you feel the RSL poses a real risk, just don't jump with one. If you choose to jump with one, be ready to operate as if it wasn't there, to include pulling your own silver handle and ignoring it unless you plan to land in water or on top of a building.


pchapman  (D 1014)

May 10, 2013, 7:01 AM
Post #41 of 161 (1908 views)
Shortcut
Re: [ryoder] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

ryoder wrote:
skydivers have the myth of the spin that remains after the cutaway.Crazy

I thought it was the myth that RSL's provide a clean opening because people don't spin after a cutaway.Smile

The rotation rate may not be a whole lot in some cases, and jumpers will sometimes stabilize themselves quickly after a cutaway, so that the effect on the reserve opening is minimal, and no twists result.

But the physics suggests one does keep the rotational momentum one has at the time of the chop.

But that's an argument that can be continued at another time and place!


dqpacker  (D 32043)

May 10, 2013, 7:27 AM
Post #42 of 161 (1871 views)
Shortcut
Re: [pchapman] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

pchapman wrote:
ryoder wrote:
skydivers have the myth of the spin that remains after the cutaway.Crazy

I thought it was the myth that RSL's provide a clean opening because people don't spin after a cutaway.Smile

The rotation rate may not be a whole lot in some cases, and jumpers will sometimes stabilize themselves quickly after a cutaway, so that the effect on the reserve opening is minimal, and no twists result.

But the physics suggests one does keep the rotational momentum one has at the time of the chop.

But that's an argument that can be continued at another time and place!

you lost your own argument.


ryoder  (D 6663)

May 10, 2013, 7:34 AM
Post #43 of 161 (1862 views)
Shortcut
Re: [pchapman] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

pchapman wrote:
I thought it was the myth that RSL's provide a clean opening because people don't spin after a cutaway.Smile

The rotation rate may not be a whole lot in some cases, and jumpers will sometimes stabilize themselves quickly after a cutaway, so that the effect on the reserve opening is minimal, and no twists result.

But the physics suggests one does keep the rotational momentum one has at the time of the chop.

But that's an argument that can be continued at another time and place!

I honestly can't tell what the jumper does after the cutaway; Even full-screen it is too small and brief. Is it possible to go back to the original file, and generate a larger video?


pchapman  (D 1014)

May 10, 2013, 7:46 AM
Post #44 of 161 (1839 views)
Shortcut
Re: [ryoder] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

ryoder wrote:
I honestly can't tell what the jumper does after the cutaway; Even full-screen it is too small and brief.

Yeah, my vid is poor. Sorry, the guy who burned the DVD screwed up the resolution and the original tape is gone.

I sure didn't stop spinning as soon as I chopped, yet at the same time I was able to flip over, slow the turn, and deploy my main with only some residual rotation after a couple seconds -- but the timing was under my control, not an RSL's.

Somewhere out on youtube there must be some outside video of spinning chops (supporting either side of the argument)...


irishrigger  (D 297)

May 10, 2013, 8:16 AM
Post #45 of 161 (1798 views)
Shortcut
Re: [ryoder] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

ryoder wrote:
Tetrahedron wrote:
Cutting away from a spinning malfunction with an RSL gives you a good chance of winding up with numerous line twists on your reserve.
It's actually a good decision to disconnect the RSL before cutting away, in that situation, but not if it takes you more than 5 seconds to disconnect it.


I do not believe that an RSL will add line twist on your reserves. i have had over 45 cutaways and the most i gotten was maybe half a twist. a lot has to do how to fly your body after a cutaway.

and i would much prefere to land with line twists on a reserve than land with a canopy that is snivling to open!

and my own personal opinion is i would much rather try to fight a line twist on reserve than fighting to get stable after a low cutaway. i do not know if he wasted 5 sec as mentioned. but if the RSL was connected he might have enough height to deal and clear a line twist on his reserve most likely.
so which is the lesser of 2 evils in this scenario?
my 2 Cents

Rodger


(This post was edited by irishrigger on May 10, 2013, 8:17 AM)


DougH  (D License)

May 10, 2013, 8:20 AM
Post #46 of 161 (1788 views)
Shortcut
Re: [pchapman] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Under my two spinning malfunctions with smaller HP canopies I was not spinning independently of the canopy along my vertical axis.

Maybe my experience isn't the norm, but based on discussions with other people with high speed diving line twists, and my own two, you end up with a good amount of vertical speed from canopy diving and your body tends to stabilize either on your back or on your belly.

The canopy may continue to spin, but it does it mostly independent of the jumper.


sundevil777  (D License)

May 10, 2013, 8:42 AM
Post #47 of 161 (1759 views)
Shortcut
Re: [dqpacker] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

dqpacker wrote:
sundevil777 wrote:
If he had difficulty cutting away, perhaps the mini 3 rings contributed to that. I don't like them at all, especially for heavier jumpers.

i've chopped 5 times with mini 3rings on highly loaded canopies spinning, and never had a problem, and i'm a bigger dude.
what might have been a real contributor to a hard cutaway is if he had hard housings in his risers.
but if his rsl was disconnected, my guess is he took too much time disconnecting it, instead of just cutting away.

Mini rings are more sensitive improper manufacture, and are more sensitive to lack of lubrication of the cable. Of course everyone should confirm that their risers are properly made and that their system is well lubed. Of course not everyone is going to do that. I like having extra margin by design. I don't know if this fatality involved difficulty cutting away related to the mini rings, but this forum is in part for speculation to inform and educate about such issues. I think it is reasonable to bring up the subject.


(This post was edited by sundevil777 on May 10, 2013, 8:45 AM)


pchapman  (D 1014)

May 10, 2013, 8:44 AM
Post #48 of 161 (1756 views)
Shortcut
Re: [DougH] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Yeah, consider that recently video from the deepseed guy with the popped toggle on a high performance canopy. His spiral descent was smooth, pretty much just a rotation on the body yaw axis, spinning at about 1 revolution per 2 seconds.

It is hard to tell exactly what is happening from inside video, but it looks like he continues to rotate after chopping, another 180 degrees, starting to slow down, perhaps partially naturally from drag and partially by his instinctive body position to counter a turn. Who knows exactly when the Cypres activated reserve streams out.

So yes he continues to turn after chopping, as physics suggests.

And yes that doesn't automatically mean a twisted up reserve, because the rotation rates and type of rotation aren't necessarily high enough, and do damp out from drag or by good body position.

Perhaps that satisfies proponents of different areas of emphasis?


sundevil777  (D License)

May 10, 2013, 8:52 AM
Post #49 of 161 (1737 views)
Shortcut
Re: [pchapman] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

In reply to:
So yes he continues to turn after chopping, as physics suggests.

Not just suggested, it's the law!

The center of gravity of the person will go out/away on a tangent, but as you "suggest" there is some rotational momentum and that doesn't stop when cutting away.


EduardoVincente  (B 5615)

May 10, 2013, 8:52 AM
Post #50 of 161 (1736 views)
Shortcut
Re: [pchapman] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Here is a video of a reserve deployment on my back from a spinning malfunction...

http://www.dropzone.com/videos/Emergencies/nakEd_s_Crazy_Cut-Away_1699.html


Divalent  (C 40494)

May 10, 2013, 8:53 AM
Post #51 of 161 (2472 views)
Shortcut
Re: [pchapman] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

pchapman wrote:
ryoder wrote:
skydivers have the myth of the spin that remains after the cutaway.Crazy

... But the physics suggests one does keep the rotational momentum one has at the time of the chop.

This video illustrates the physics of the situation: a puck on an air table rotates about a central point, attached by a string. When the string is cut, the puck departs in a straight line, but with rotation. This is well known physics (at least to those that understand classical mechanics).

http://www.youtube.com/watch?v=AzgasHgVOy8


pchapman  (D 1014)

May 10, 2013, 9:03 AM
Post #52 of 161 (2458 views)
Shortcut
Re: [Divalent] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Re: puck video.

Thanks!! Tho' the table is so small it is hard to see the puck rotate much after being released.


And MODS: All this rotating discussion and what happens after a cutaway, would be good to chop out and spin off to a thread of its own. It has gotten a bit away from the original incident...

Now I really gotta get some work done.


BillyVance  (D 18895)

May 10, 2013, 9:19 AM
Post #53 of 161 (2443 views)
Shortcut
Re: [wmw999] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

wmw999 wrote:
I've had a couple of spinning mals on a Diablo -- they spin pretty good, and in both cased my RSL activated my reserve with neither incident nor line twists.

If you're thrown away from your spinning main, the rotation that was happening around your main is going to stop, because the fulcrum (the main) is gone. If you were also twisting (i.e. either the spinning line twists were twisting up worse or untwisting) that component can stay with you I believe.

Wendy P.

My first mal was a tension knot spinner on a Triathlon 135 with an RSL. I did open under a Tempo reserve with a couple of line twists that I had just enough time to kick out of and fly back to the DZ from over the woods, a pond and more woods, clearing the tree line with yards to spare after a 60+ way jump. Crazy

I had wondered if the line twists were an aberration or if the main with the RSL caused the freebag to make a couple revolutions before the reserve came out?


gearless_chris  (D 29012)

May 10, 2013, 9:41 AM
Post #54 of 161 (2421 views)
Shortcut
Re: [davelepka] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

davelepka wrote:
I'll admit that there are some very specific circumstance where a jumper could have some 'personal' rotational momentum built up that could remain after the chop. That said, I have never heard of a jumper who got wrapped up in a reserve bridle or lineset, the worst I've heard of line twists. To that end, I've also heard of line twists on an otherwise 'clean' cutaway and reserve deployment.

Those very specific circumstance would certainly be some of the most violent, disorienting and high-speed malfunctions, making it the worst possible time to be concerned with trying to disconnect an RSL, and then playing the losing game of trying to get stable before pulling your own reserve.

I maintain that the best course of action in such circumstances would be an immediate cutaway and reserve deployment. Less altitude loss, less disorientation and more time to kick out of any reserve line twists if they should occur.

Let's remember that a malfunction only occurs after you have decided it was time to end the skydive. Your main might have different ideas, but in any case you're going much faster than you wanted to be at the given altitude. Staying on track, and slowing yourself way down should be your #1 priority, and analyzing the nature of your mal and reconfiguring your rig to match is not conducive to stopping anything.

If you feel the RSL poses a real risk, just don't jump with one. If you choose to jump with one, be ready to operate as if it wasn't there, to include pulling your own silver handle and ignoring it unless you plan to land in water or on top of a building.

My friend Dan went in on 8/3/2008 due to a reserve bridle entanglement after cutting away from a spinning lineover. It was around his waist twice, so there was no rolling out of it either. None of us had heard of such a thing before, or since then. I think the odds of that happening are astronomical.


Premier faulknerwn  (D 17441)
Moderator
May 10, 2013, 10:00 AM
Post #55 of 161 (2406 views)
Shortcut
Re: [pchapman] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Here is video of 2 chops I had a couple of years ago. The first one was on a CRW jump - so I opened at 12 grand. It was on a Lightning 113, and I chopped at 9k or so. That is why I took a while to try and get stable before dumping my reserve. The rig was a Racer, and the reserve was a Tempo 120.

The second was after an AFF jump - I probably opened at 3500 or so. Sabre 135 - probably was a lineover but I'm not sure. I slow-mo'ed my actual chop as you can see the reserve bridle launch. I dumped my reserve as soon as I cutaway just because I knew I was getting towards 2k. The rig was a Racer, and the reserve a PD 126. The line twists on the PD reserve were so stable I had a hard time getting them out!

So even though both of these canopies are relatively "docile" in the grand scheme of modern canopies - you can see I was clearly getting thrown around a lot on a spinning mal.

That being said - I do believe in RSLs for the vast majority of jumpers. Better to have a reserve with line twists than no reserve at all. I just don't believe that you are instantly not spinning as soon as you chop.

http://www.youtube.com/watch?v=Ft6HnnosbDQ




Premier Remster  (C License)

May 10, 2013, 11:25 AM
Post #57 of 161 (2338 views)
Shortcut
Re: [Various people] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Yes, you MAY have twists under your reserve. But rigging mid-mal is a recipe for not getting uner any kind of reserve.


gowlerk  (C 3196)

May 10, 2013, 11:47 AM
Post #58 of 161 (2317 views)
Shortcut
Re: [Remster] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Line twists on reserve deployments are very common. (see my icon for an example) They are no big problem to deal with. The more altitude you have, the better no matter what your problem is.

On the other hand you could decide to mess with your RSL before cutting away. But your cutaway and reserve handles are large and placed in an easy to find and easy to see location. While your RSL bail clip is a tiny device you can find by feel only and is really only meant for use on the ground or under a good controllable canopy on a windy day.

If you feel you may need to disconnect your RSL before cutting away you should not get into the airplane with it connected. It's not designed to work that way. I mean really, most situations that require a cutaway will involve a spinning canopy of some sort. If you are not willing to cut away a spinner with your RSL you should not use an RSL. You need to make this decision BEFORE you jump.

Ken


(This post was edited by gowlerk on May 10, 2013, 12:01 PM)


The111  (D 29246)

May 10, 2013, 12:06 PM
Post #59 of 161 (2299 views)
Shortcut
Re: 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Re: all the discussion about disconnecting RSL's.

It's a good discussion, but keep in mind that it is speculation whether or not it has anything to do with this incident.

Here is a story that leads to a completely different type of speculation. My last cutaway, several years ago, I had an RSL. I checked on the ground, and on the plane that it was connected. When I cutaway, I was pretty high (~5k ft) so I waited a couple seconds to pull silver. I ended up being nearly knocked unconscious (not really related to this discussion), and because of that didn't think much about my RSL until I landed. It was then that it occurred to me... "why was I able to delay those few seconds?" So I looked down on my rig and sure enough the RSL was still in place with the shackle wide open. I did a lot of digging and eventually found some info that IIRC was corroborated by Bill Booth: the RSL shackle is the "weak point" in the system (weak in terms of bulletproof design, not in terms of force transfer capability) and has been known historically to sometimes come disconnected on its own in an actual use scenario.

So it's completely possible the jumper in this incident had a similar occurrence, and this has nothing to do with midair rigging attempts. The take home from that speculative branch is of course the old "if you have an RSL, don't rely on it."


Premier DSE  (D 29060)

May 10, 2013, 12:56 PM
Post #60 of 161 (2248 views)
Shortcut
Re: [The111] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

The111 wrote:
The take home from that speculative branch is of course the old "if you have an RSL, don't rely on it."

I have the small Wichard snap shackle (same as used for RSL) on my camera wings. There have been a few instances where they've come undone mid jump, even though the spring has been lubed and the pull tab changed out for a smaller tab. Yes, they can come undone.


winsor  (D 13715)

May 10, 2013, 6:00 PM
Post #61 of 161 (2145 views)
Shortcut
Re: [ryoder] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

ryoder wrote:
Tetrahedron wrote:
Cutting away from a spinning malfunction with an RSL gives you a good chance of winding up with numerous line twists on your reserve.
It's actually a good decision to disconnect the RSL before cutting away, in that situation, but not if it takes you more than 5 seconds to disconnect it.

The moment you cutaway, you fly away from the canopy feet-first in a straight line. The relative wind is blowing from your feet toward your head.

You can simulate this by tying a weight to the end of a cord, then spinning it overhead and letting it go. The spin ends the moment it is released.

Oh, I dunno.

My limited experience in the matter involved being under a violently spinning main, on my back, with the left steering line half-hitched over my altimeter (I'd tried to clear a lineover).

Since it struck me that I should do something very quickly, but that the steering line could well remover fingers if I wound up hanging under it, I executed a gunslinger cutaway (cutaway and reserve pulled simultaneously).

The freebag cleared the trash with the better part of a foot to spare (judging by the video), and the reserve opened with four line twists. The steering line was twisted up in the reserve suspension lines until I kicked out of the twists, and I wound up landing while still towing the main by the knot around my left hand (I regained feeling in my left ring fingertip about a year and a half later).

YMMV, but I still had plenty of angular momentum after chopping - but I also had plenty of altitude with which to work to get under control and land in one piece.

I have no interest in doing it again, so you will please excuse me for my scanty knowledge of the subject.


BSBD,

Winsor

P.S.: No RSL, jumping camera on a 1992 Racer.


(This post was edited by winsor on May 10, 2013, 6:01 PM)


wrightskyguy  (D 19665)

May 11, 2013, 4:59 AM
Post #62 of 161 (1965 views)
Shortcut
Re: [Tetrahedron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

In reply to:
forgot this forum is ruled by dinosaurs.

I'll leave you all to it. Bye.

Quote:
You give out bullshit advice and you get called on it, now you're gonna take your ball and go home. BTW, the dinosaurs are exactly right. Are you even a skydiver?


popsjumper  (D 999999999)

May 11, 2013, 5:21 AM
Post #63 of 161 (1955 views)
Shortcut
Re: [Tetrahedron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

In reply to:
I forgot this forum is ruled by dinosaurs.

I'll leave you all to it. Bye.

Hold on...don't leave yet.
I have a card....it's here somewhere.
My Old Fart Qualification/Verification card,


Now where did I put that.....hmmmmmm.


ChrisD  (No License)

May 11, 2013, 8:18 AM
Post #64 of 161 (1861 views)
Shortcut
Re: [captain1976] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

This may sound a little corney,

I faced to the West after reading this one, and I said " please don't let me fuck around if something happens,...just cutaway and find the god damn reserve,...even if I end up with two out, ,..."

We will never fully know what happened to our friend. But please train me to fight rather than think,...
C




robinheid  (D 5533)

May 11, 2013, 11:27 AM
Post #66 of 161 (1743 views)
Shortcut
Re: [gowlerk] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

gowlerk wrote:
But your cutaway and reserve handles are large and placed in an easy to find and easy to see location. While your RSL bail clip is a tiny device you can find by feel only and is really only meant for use on the ground or under a good controllable canopy on a windy day.

Your observation leads to another important point: We lose fine motor control under stress, so because we use our fingertips to deal with the teeny tiny RSL release, doing that in the middle of a malfunction will automatically be harder to do because of that, independently of position, tension, etc.

On the other hand, we do not use our fingertips to deal with the release and reserve handles; we use the larger muscles of the hand and forearm, so stress-related "dexterity degradation" is minimal.

When you add this factor to everything else involved with handling a spinning malfunction, it doesn't seem like a very good idea to me to try to disconnect the RSL in the middle of the maelstrom -- unless you were initially open at 3,500 feet or higher, in which case you would have more time and less stress to disconnect it.

Frown
44


jerm  (D 23994)

May 11, 2013, 3:03 PM
Post #67 of 161 (1654 views)
Shortcut
Re: [winsor] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

I think the big debate here is because the "you don't rotate after a cutaway" people are thinking in "ideal", 2D, point-in-a-vacuum physics and have either never been in a big-G mal or got very, very lucky when they were.

In the real world, a skydiver with asymmertric mass, asymmetric surface area and drag profiles moving not only tangentially (upon cutaway) to the spin but also with the non-trivial (esp under an HP main) vertical componant and resultant quickly changing relative wind.

And even all that doesn't take into account any delay in the release of each set of risers -- a delay built-in in order to make sure that the (potential) RSL-equipped riser will always release last in order to avoid the RSP deploying the reserve with one side still attached. It may be a very-very short delay, but physics doesn't have a grace period. Unser normal circumstances this has a negligible effect but in high-G situations it doesn't take much to induce a spin

Also... as preciously stated, when someone chops they are released at a tangent line to their rotational disk.. this is NOT feet first... rough sketch: http://cl.ly/image/2k1f3H331d2X Even if you start on your belly you still have all of the above to take into account AND you're not in a particularly non-rotation-producing body position right away. best case... more likely you're on your side or back


f94sbu  (D 16017)

May 11, 2013, 4:04 PM
Post #68 of 161 (1626 views)
Shortcut
Re: [jerm] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

You are absolutely true. The rotational momentum of your body (a body that is forced to move in a circle due to canopy) will stay after you cut away and it will keep you spinning after the cutaway. HOWEVER, your rotational speed is not that high that it will introduce multiple line twists.
For arguments sake, lets say that a jumper ended up with 4 twists and the approximate time for reserve deployment is 2 seconds. That means that the jumper must have spun around his own axis 4 times during the reserve deployment. In order to do this, the spinning malfunction must also rotate around its axis 4 times per two seconds. That is a rotational speed of 2 revolutions per second. Assuming that your body is 2 meters away from the center of rotation, the G-forces would be in the order of 30 G! I think it is pretty clear that a malfunction does not rotate this quickly and the number of line twists on the reserve has a huge number of other factors (body position, etc.) other than just the small rotational momentum left after the actual cut away.

All in all, yes, the body will have some rotational momentum after the cutaway (this is the laws of physics, so no need to debate this) however, the momentum is too small to have a major impact on exactly how the reserve deploys. Just as a guess, I would say that if the left and right risers release with a small delay, it will introduce a much higher momentum on your body compared to the rotation from the cutaway.

In any case, regardless who is right or wrong on the physics part of this, I would much rather have a reserve with line twists at 300 feet than no reserve at all at 100 feet. The more altitude you have, the more time you have to deal with the line twists, but if you cut away low, you have no choice but to deploy your reserve asap regardless if you have a RSL or not.


D2216  (D 2216)

May 11, 2013, 5:09 PM
Post #69 of 161 (1592 views)
Shortcut
Re: [captain1976] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Obituary for Mr. Santiago Pedro Rosell Sr
Santiago (Sandy) Rosell passed away on Wednesday, May 8, at the age of 62.

He was born on September 11, 1950 in Havana, Cuba, and raised in Miami, Florida.

After earning a Masters of Arts Degree in Communications from the University of Central Florida, Sandy attended Naval Aviation Officer Candidate School, in Pensacola, Florida, and became a U.S. Navy jet fighter pilot. He was aircraft carrier qualified aboard the USS Lexington, and, while flying T-28s, T2Cs, and A-4Js, rose to the rank of Lieutenant Commander.

Following distinguished service with the U.S. Navy, Sandy continued his extensive aviation career by founding an aviation maintenance management firm. There, as Chief Pilot for Venture Airways, he flew both jets and helicopter aircraft for United Medical Corporation.

Most recently, he was the Chief Pilot for A-OK Jets, Inc., flying internationally for John W. Henry & Company and the Boston Red Sox baseball team.

He was a consummate pilot, a pilots pilot. Involved in world-wide international flight operations, he was rated in Challenger, Falcon and Gulfstream aircraft, and was dual rated in rotorcraft.

Besides his extensive aviation career, Sandys vast interests spanned many activities, from photography to motorcycles and sports cars, and much more. In the world of parachute jumping, he was Advanced Free Fall certified, and enjoyed the sport immensely.

Sandy never met or knew a stranger, and his friends were many. He made each one feel special, so special that many felt Sandy was their closest friend.

He left behind a loving wife, Linda, son Sandy Jr., and step son Kenneth.

His enormous presence of spirit, and his unbridled joy for life and living, will never be forgotten.

He will be deeply missed.

A funeral will be held 2:00 p.m. Tuesday, May 14, at the Annunciation Catholic Church, 1020 Montgomery Road, Altamonte Springs, Florida, followed by a church reception.

A Memorial Fund has been established to help carry on an effort of great, great importance to Sandy.
His fervent wish was to see his son, Sandy Jr., graduate from Embry-Riddle Aeronautical University, and after to accrue sufficient aircraft hours to become a highly employable commercial pilot.

To further Sandys loving dream that his son follow in his aviation footsteps, contributions are warmly welcomed.

Checks may be made payable to the Santiago Rosell Memorial Account, and mailed to BMO Harris Bank, 129 E. Gore Street, Orlando, FL 32806. Arrangements entrusted to DeGusipe Funeral Home & Crematory.
Attachments: Sandy Rosell.jpg (52.0 KB)


chuckakers  (D 10855)

May 12, 2013, 7:06 AM
Post #70 of 161 (1380 views)
Shortcut
Re: [IronEddie42] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

So maybe he was thinking that because he was under a spinning malfunction that he needed to disconnect his RSL and that could explain the hesitation going to his reserve.
In reply to:

I don't know this jumper, but based on the comments I've read here he was quite competent. I doubt the scenario you describe was in play.

And a note to the noobs - NEVER take time to disconnect your RSL during a mal, spinning or not.


mik  (D 11111)

May 12, 2013, 7:34 AM
Post #71 of 161 (1362 views)
Shortcut
Re: [chuckakers] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Has the experience and main canopy size been confirmed?

The original post made reference to a "highly experienced" jumper probably on a 200+ canopy but later posts indicate 400-500 jumps (maybe a little more) and a 150 main. I am assuming that the latter posts may be accurate but would be interested to find out for sure. Thanks.


parkair  (D 33246)

May 12, 2013, 7:50 AM
Post #72 of 161 (1348 views)
Shortcut
Re: [mik] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Later posts are correct. Apache 150 canopy....approximately 450-500 jumps. Very current, heads up jumper.


Premier skybytch  (D License)

May 12, 2013, 8:05 AM
Post #73 of 161 (1335 views)
Shortcut
Re: [pchapman] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

In reply to:
I would sure not like to have an RSL pop the reserve when spinning like that on my back!

Dunno bout you, but I'd MUCH rather go in with line twists than at line stretch.


mik  (D 11111)

May 12, 2013, 8:51 AM
Post #74 of 161 (1310 views)
Shortcut
Re: [f94sbu] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

FWIW I have had 2 mals where I found myself spinning wildly. Both times I had an RSL fitted.

When I cut away the first (line twists, about 8 years ago, from memory on a Pilot 150, when I had between 200 and 300 jumps) I found myself under a reserve with about 6 line twists. Although I was pretty stressed about this, the canopy flew straight while I kicked them out. My equally low-jump number, non-rigger friends advised me to ditch the RSL as being the likely cause of the reserve line twists. For a while I did then I researched RSLs in more detail and decided to use one again.

The second "spinning" mal like this was last year, when I had a lineover on a Pilot 124. This time, the reserve flew perfectly straight on opening - no line twists.

My knowledge of physics is very limited so I cannot contribute to that debate but perhaps my experience is of some relevance. Bottom line for me is that my next rig will most likely have an RSL.


TonyJ  (D 24244)

May 12, 2013, 12:55 PM
Post #75 of 161 (1190 views)
Shortcut
Re: [DSE] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

I had a really hard opening, damaged canopy.. cut away and pulled the reserve... I told my buddy I could believe how fast the rsl pulled the pin.. till he pointed it out that it was still on the rig open.. when I left the plane it was connected. Though it was a large brass one.. my first cutaway.. tony


captain1976  (D 7183)

May 12, 2013, 1:14 PM
Post #76 of 161 (2100 views)
Shortcut
Re: [mik] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

mik wrote:
Has the experience and main canopy size been confirmed?

The original post made reference to a "highly experienced" jumper probably on a 200+ canopy but later posts indicate 400-500 jumps (maybe a little more) and a 150 main. I am assuming that the latter posts may be accurate but would be interested to find out for sure. Thanks.

Sorry everyone, I posted him as "highly experienced" in error as I meant to state "reasonably experienced" and there is a limited amount of time you can edit your posts here.

Additionally, the canopy size was reported to me as being what I originally stated by his packer.


JohnMitchell  (D 6462)

May 12, 2013, 9:53 PM
Post #77 of 161 (1926 views)
Shortcut
Re: [Tetrahedron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

 

What would you say the reason is that most skydivers prefer to not use an RSL?

I forgot this forum is ruled by dinosaurs.The main reason? Because they want to look cool and have mad skilz. Too many people have died that would have lived if they had used an RSL.

Am I a dinosaur? Sure, maybe. But I lived thru rounds and the transition to squares and the golden age of experimentation with all kinds of ideas that turned out to be really bad. I have a pretty good idea of what works and how people die.


normiss  (D 28356)

May 12, 2013, 10:37 PM
Post #78 of 161 (1909 views)
Shortcut
Re: [JohnMitchell] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Had a rigger laugh at me - "real jumpers don't use RSL's"

Well THIS jumper no longer uses THAT rigger!

Wink


JohnMitchell  (D 6462)

May 13, 2013, 7:49 AM
Post #79 of 161 (1727 views)
Shortcut
Re: [normiss] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

normiss wrote:
Had a rigger laugh at me - "real jumpers don't use RSL's"

Well THIS jumper no longer uses THAT rigger!
CrazyCrazy

Good move.Smile I wonder if he thought AAD's were for pussies. Laugh


jacketsdb23  (D 29802)

May 13, 2013, 8:10 AM
Post #80 of 161 (1703 views)
Shortcut
Re: 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Do people really have an issue with line twists on their reserve? Somebody point me to the statistic of fatalities with someone going in on line twists on their reserve.

I don't think its much of a reach to say no pull / low pull numbers are much higher.

If you choose not to jump an RSL thats fine, I don't use one either. But its not because I'm afraid of going in on line twists with the reserve. That sounds like false justification for convenience.

RSL's work and have saved lives. And please, for the young jumpers reading this, never try to disconnect an RSL during a spinning malfunction. Thats ridiculous, and I'm not a dinosaur.


JohnMitchell  (D 6462)

May 13, 2013, 8:16 AM
Post #81 of 161 (1716 views)
Shortcut
Re: [jacketsdb23] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

jacketsdb23 wrote:
Do people really have an issue with line twists on their reserve? Somebody point me to the statistic of fatalities with someone going in on line twists on their reserve.
Awesome good point. Thank you. Cool

In reply to:
I don't think its much of a reach to say no pull / low pull numbers are much higher.
It's killed a bunch of good people recently. Unsure

In reply to:
RSL's work and have saved lives. And please, for the young jumpers reading this, never try to disconnect an RSL during a spinning malfunction. Thats ridiculous, and I'm not a dinosaur.
I caught some noobs wanting to turn off their AAD's for a hop & pop the day after we had a low-pull/two-out injury. If you need to disconnect your safety equipment because of what you're doing on a jump, you need to reconsider what you're doing. Wink


chuckakers  (D 10855)

May 13, 2013, 8:33 AM
Post #82 of 161 (1688 views)
Shortcut
Re: [pchapman] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

pchapman wrote:

If you are rotating under the mal, you will rotate when you cutaway. You do have rotational momentum, that will rotate you as you chop. You may be spinning or rolling when you chop, and will continue to do so for some time after the chop.....

Funny, I've chopped 5 or 6 highly loaded, fast spinning Velos and never ONCE continued to turn/spin/rotate after the cutaway. How would you explain that?


jcrouch  (D 16979)

May 13, 2013, 8:57 AM
Post #83 of 161 (1654 views)
Shortcut
Re: [chuckakers] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

I've been in 8 spinning line twist malfunctions, all with RSLs, a couple wearing a camera. In every case I was under a fully inflated reserve with no line twist about 100 feet below my main canopy. The reserve deployed as I traveled almost horizontally away from my main canopy. Worked great for me!


grimmie  (D 18890)

May 13, 2013, 9:16 AM
Post #84 of 161 (1637 views)
Shortcut
Re: [chuckakers] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Sometimes we witness accidents in this sport that make ZERO sense to us. It's easy to sit at the computer and sip some coffee and monday morning quarterback an incident. Skydivers get on here and start to wildly speculate, bring up physicics charts, call people dinosaurs and tell all sorts of " no shit, there I was stories".

When an incident happens, sometimes it's the simplest of answers as to why.

I have witnessed some pretty crazy stuff over the past 23 years of jumping. As an S&TA I have interviewed a lot of jumpers after a mishap. Here are some common traits in an incident that surviving jumpers discussed...

I thought I was higher.
I thought i had more time.
I thought I could fix it.
I thought i could land it.
I panicked.
I was scared and froze up.
I brainlocked on my cutaway and reserve handle, which was which.
I heard my audible blasting in my ear and was distracted by it.
I didn't do a canopy control check.
I didn't look before I turned.
I thought I tracked far enough.
I looked at my canopy and didn't realize it was a step through and thought I could fix it.
I froze up.
I was told by a jumper once to...(insert bad advice here).
I never had a cutaway before and was scared to chop.
I thought my AAD would fire.

Recently there have been a lot of low cut away incidents.
I'm not sure if we have a training issue or a complacency issue.
Stay current, review your EP's.
Ask an intructor for advice if you're not sure.
Know your gear.

Sometimes it's just the simple things...


pchapman  (D 1014)

May 13, 2013, 9:26 AM
Post #85 of 161 (1625 views)
Shortcut
Re: [chuckakers] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

chuckakers wrote:
Funny, I've chopped 5 or 6 highly loaded, fast spinning Velos and never ONCE continued to turn/spin/rotate after the cutaway. How would you explain that?

Maybe with all those skydives you were crappy at at performing a physics demonstration, having other things on your mind, and unconsciously adopted a body position that would counter the turn (and any roll) very quickly after chopping! Smile

Some skydivers, including some RSL proponents, thought that rotational momentum does not transfer after chopping. But the evidence in this thread does show clearly that it does. (Largely through video and physics thought experiments, although not through physics equations-on-blackboard stuff.)

That does not mean that the rotation after chopping is always fast, nor that it can't be countered, nor that it doesn't slow naturally from drag. Nor do RSL activated reserves spin up all the time or even most of the time. Nor does it mean that RSL's are evil.

But I did want to counter one factually incorrect concept that some people had learned.


Premier billvon  (D 16479)
Moderator
May 13, 2013, 9:36 AM
Post #86 of 161 (1613 views)
Shortcut
Re: [jacketsdb23] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

>Do people really have an issue with line twists on their reserve?

Some do. When you load a reserve at close to 2:1 (and yes I know a few people who do this) then line twist is a big deal.

Of course there's a simple solution to that, but it would not result in them having the smallest rig on the DZ.


mstlaurent  (C 3321)

May 13, 2013, 11:09 AM
Post #87 of 161 (1538 views)
Shortcut
Re: [chuckakers] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

The truth is, Newton's laws and the law of conservation of rotational energy apply to skydivers too...

This is as true as parachutes don't go up at opening. Cool


You have the same quantity of energy just before and just after the cutaway.

But before the cutaway you rotate around the canopy or around a point further away. This generates centripetal force which disappears at the moment you cut away. From then you rotate around yourself. The feelings from those two different rotations are very different and this may explain in part why it looks like the rotation stops.

The second explanation, which probably has even more effect, is that you can change your rotational speed considerably just by changing your arms and legs position. Just think about a figure skater doing spins.

During and just after the cut away, your arms are close to your body (on the handles) and your feet are probably quite close together because of the centripetal force. And at this moment you rotate (yes!). Then you just have to open your arms and legs to almost stop your rotation, which is what we are trained to do, take the box position.

Hope this makes sense and helps

Cheers


crotalus01  (B 28932)

May 13, 2013, 1:57 PM
Post #88 of 161 (1429 views)
Shortcut
Re: [mstlaurent] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

I had a Sabre 190 that broke 9 lines on opening and put me on my back in the hardest spin I have ever been in (really didnt know a 190 could rotate that fast). I chopped it immediately because I was already in the basement (deployed at 1800', my fault and another story), my RSL beat me to silver and my reserve came out with about 12 linetwists. I had just enough time to kick them out before I landed. As I was walking back to the hanger a jumper with 2000+ jumps remarked that it was the most linetwists he had ever seen on a reserve.
I chose to disconnect my RSL after that experience. I have had 2 chops without it hooked up so I have no doubts in my ability to perform my EPs.


Premier wmw999  (D 6296)

May 13, 2013, 2:15 PM
Post #89 of 161 (1413 views)
Shortcut
Re: [crotalus01] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Quote:
I have had 2 chops without it hooked up so I have no doubts in my ability to perform my EPs.
I can see why you'd worry about the RSL. OTOH, it's not just for whether you can perform your EPs (I know I can -- I'm from the days when you were dead until you did something). But when I dumped below 2 (bigway) and had a spinner on my Diablo, I wasn't unhappy to have my reserve open so quickly after I cut away.

No line twists for me -- as I said, had I had that many, I might have ended up changing my story too. Of course, then when I had a similar malfunction, also below 2 (another bigway), I would have been under my reserve lower. I cut away with both hands, and pull my reserve with both hands. Small hands, more certainty.

Everyone needs to think about these kinds of situations to really know why they're making the decisions they are. There are valid arguments in both directions -- but you have to actually understand them, and not just parrot them.

Wendy P.


jacketsdb23  (D 29802)

May 13, 2013, 4:32 PM
Post #90 of 161 (1328 views)
Shortcut
Re: [crotalus01] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

crotalus01 wrote:
I had a Sabre 190 that broke 9 lines on opening and put me on my back in the hardest spin I have ever been in (really didnt know a 190 could rotate that fast). I chopped it immediately because I was already in the basement (deployed at 1800', my fault and another story), my RSL beat me to silver and my reserve came out with about 12 linetwists. I had just enough time to kick them out before I landed. As I was walking back to the hanger a jumper with 2000+ jumps remarked that it was the most linetwists he had ever seen on a reserve.
I chose to disconnect my RSL after that experience. I have had 2 chops without it hooked up so I have no doubts in my ability to perform my EPs.

You just confirmed my point. Lots of line twists, you landed fine. Sure as hell beats a nothing out, or line stretch reserve canopy. There is also a video somewhere out there in Deland (maybe?) of a guy with massive line twists on his reserve and he kicked out of them just in time to land.

I'll still argue the statistics don't point to a problem with fatalities and line twists on reserves. However, the same can't be said for low or no pulls.

Just food for thought.


Pablo.Moreno  (C 13216)

May 13, 2013, 5:41 PM
Post #91 of 161 (1282 views)
Shortcut
Re: [jacketsdb23] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

You have higher chances of surviving landing with a line twist than a reserve half way open.

Then again if I would be flying a canopy loaded at 2.5 to 1, that would be another story and another opening altitude.


wolfriverjoe  (A 50013)

May 13, 2013, 6:21 PM
Post #92 of 161 (1255 views)
Shortcut
Re: [chuckakers] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

chuckakers wrote:
pchapman wrote:

If you are rotating under the mal, you will rotate when you cutaway. You do have rotational momentum, that will rotate you as you chop. You may be spinning or rolling when you chop, and will continue to do so for some time after the chop.....

Funny, I've chopped 5 or 6 highly loaded, fast spinning Velos and never ONCE continued to turn/spin/rotate after the cutaway. How would you explain that?

Well, I would guess (and it's just a guess) that you were spinning relatively slowly after the cutaway. Slowly enough that before you could make a noticeable rotation, your reserve PC was out and the drag from that (and from the subsequent reserve deployment) stopped the rotation completely.

IOW, the RSL puts the reserve out fast enough that you won't rotate enough to matter, even though physics dictates you do retain that rotational momentum.


chuckakers  (D 10855)

May 13, 2013, 6:37 PM
Post #93 of 161 (1245 views)
Shortcut
Re: [wolfriverjoe] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

wolfriverjoe wrote:
chuckakers wrote:
pchapman wrote:

If you are rotating under the mal, you will rotate when you cutaway. You do have rotational momentum, that will rotate you as you chop. You may be spinning or rolling when you chop, and will continue to do so for some time after the chop.....

Funny, I've chopped 5 or 6 highly loaded, fast spinning Velos and never ONCE continued to turn/spin/rotate after the cutaway. How would you explain that?

Well, I would guess (and it's just a guess) that you were spinning relatively slowly after the cutaway. Slowly enough that before you could make a noticeable rotation, your reserve PC was out and the drag from that (and from the subsequent reserve deployment) stopped the rotation completely.

IOW, the RSL puts the reserve out fast enough that you won't rotate enough to matter, even though physics dictates you do retain that rotational momentum.

I don't use an RSL, and in most of my chops I was wearing a camera. It also didn't notice any rotation.

And your comment on the reserve p/c stopping any rotation makes no sense at all. Maybe you can explain that one.


gowlerk  (C 3196)

May 13, 2013, 8:51 PM
Post #94 of 161 (1165 views)
Shortcut
Re: [crotalus01] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Quote:
(deployed at 1800', my fault and another story)

And then you had a high speed spinner that you cut away from? And somehow you think you would have been better off taking the time to get "stable" before deploying your reserve? How much time would you have had to do that? You should be glad that 12 line twists is all that happened to you. Your RSL saved your ass there.


Premier skydiverek  (C 41769)

May 14, 2013, 1:02 AM
Post #95 of 161 (1084 views)
Shortcut
Re: [gowlerk] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

gowlerk wrote:
Quote:
(deployed at 1800', my fault and another story)

And then you had a high speed spinner that you cut away from? And somehow you think you would have been better off taking the time to get "stable" before deploying your reserve? How much time would you have had to do that? You should be glad that 12 line twists is all that happened to you. Your RSL saved your ass there.

+1 !


f94sbu  (D 16017)

May 14, 2013, 1:34 AM
Post #96 of 161 (1077 views)
Shortcut
Re: [crotalus01] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

crotalus01 wrote:
I had a Sabre 190 that broke 9 lines on opening and put me on my back in the hardest spin I have ever been in (really didnt know a 190 could rotate that fast). I chopped it immediately because I was already in the basement (deployed at 1800', my fault and another story), my RSL beat me to silver and my reserve came out with about 12 linetwists. I had just enough time to kick them out before I landed. As I was walking back to the hanger a jumper with 2000+ jumps remarked that it was the most linetwists he had ever seen on a reserve.
I chose to disconnect my RSL after that experience. I have had 2 chops without it hooked up so I have no doubts in my ability to perform my EPs.

Lets do the math to see if your logic holds together:
Taking the line length of a Sabre 190 into account + riser length etc. it is a fair assumption that your body will be at least 2-3 meters away from the center of the rotation. After watching countless cutaways, I think it is safe to assume that your reserve was fully deployed 3 seconds after the cutaway. IF the rotation from the malfunction caused the linetwists on the reserve, you must have been rotating with 4 revolutions per second just before the cutaway. This means that you were subjected to 128 - 192 G just prior to the cutaway. No one is able to withstand such G forces without passing out (and dieing ) almost instantly.
I think it is fairly safe to say that the line twists on your reserve was not caused by the RSL firing your reserve too early. Without the RSL, how long would you have waited to deploy your reserve and what would you have done in the meantime? I hope you realize that you loose altitude a lot faster when you are in freefall trying to find a stable belly to earth position than you do under a reserve with line twists.
Your spinning main might have given you 1 or 2 twists, the others were from factors that we can only speculate about. Question is, would you have been able to eliminate all those factors while being disoriented after a spinning main, quickly loosing altitude after the cutaway. Chances are that you would have never lived to tell the story about your cutaway if you had been jumping without an RSL and waited with silver much longer than your RSL waited.

Bottom line, if you wish to jump without and RSL for whatever reason, that's fine by me, but please please do not use your story to convince anyone else that they should disconnect their RSL.


crotalus01  (B 28932)

May 14, 2013, 4:41 AM
Post #97 of 161 (1008 views)
Shortcut
Re: [gowlerk] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

The RSL may or may not have factored into the linetwists - I dont know. I had one hand on each handle and was less than 1 second between the cutaway and reserve fire. I didnt look at my reserve cable to see if it was kinked after the fact. As stated I was well aware I was low and I just wanted a landable canopy over my head ASAP. However, the fact that the RSL -could- have caused the linetwists was definitely a factor in my decision to disconnect it. Another reason is that I do a lot of altitude hop and pops and CRW. Now that I am starting to do more RW I am considering reconnecting it (and since I retired the Sabre I think it very unlikely I will end up with that many broken lines again).
Edit - I was not advocating anyone to disconnect their RSL.


(This post was edited by crotalus01 on May 14, 2013, 4:46 AM)


Premier wmw999  (D 6296)

May 14, 2013, 4:57 AM
Post #98 of 161 (993 views)
Shortcut
Re: [crotalus01] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

The thought process you put into disconnecting your RSL when you did was completely valid in my eyes. There are perfectly valid reasons not to have one, and CRW is an outstanding contender.

If I did enough CRW that I had to include thinking about the RSL in my EPs on a significant number of jumps, I'd take it off, too.

One thing we need to include in the thinking process is whether it's a "regular" RSL or a Skyhook.

Wendy P.


pchapman  (D 1014)

May 14, 2013, 5:49 AM
Post #99 of 161 (956 views)
Shortcut
Re: [f94sbu] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

f94sbu wrote:
Lets do the math to see if your logic holds together:
[..] This means that you were subjected to 128 - 192 G just prior to the cutaway.

Come on... even many students find out that they can have a canopy "open with" just one full line twist... but they keep rotating underneath until they have a few more twists.

(Whether or not the jumper you were replying to actually had exactly 12 twists...)

RSL's might get to be more accepted if some of their proponents didn't scare others away by going so weird with the math and physics. CrazySmile


GoneCodFishing

May 14, 2013, 7:03 AM
Post #100 of 161 (896 views)
Shortcut
8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

As it's said, an image is worth 1000 words...

Down the page on the UPT/Skyhook website there's a Skyhook cutaway sequence from a spinning canopy along with 'time stamps'. Make of that as you will.

[inline skyhook_all.jpg]

All said, if the choice is a reserve with line twists at 200ft or a snivelling bag of shit at 10ft i know which one i'd choose Unsure


(This post was edited by GoneCodFishing on May 14, 2013, 7:12 AM)
Attachments: skyhook_all.jpg (134 KB)


pchapman  (D 1014)

May 14, 2013, 7:11 AM
Post #101 of 161 (3369 views)
Shortcut
Re: [GoneCodFishing] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Fixed your (now edited out) link & clickified:
http://www.unitedparachutetechnologies.com/...hook/skyhook-all.jpg


The Skyhook does work fast, no doubt about that.

Notice how the jumper chopping the spinning "mal" rotated 180 degrees in the 1.0 seconds from the chop Wink

(Not enough to normally cause problems!)


(This post was edited by pchapman on May 14, 2013, 7:12 AM)


GoneCodFishing

May 14, 2013, 7:15 AM
Post #102 of 161 (3364 views)
Shortcut
Re: [pchapman] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Sorry for that, been trying to get the inline image feature to work Wink

Oh, and yes, the spin after the cutaway is what i was trying to point out.


(This post was edited by GoneCodFishing on May 14, 2013, 7:32 AM)


f94sbu  (D 16017)

May 14, 2013, 7:52 AM
Post #103 of 161 (3337 views)
Shortcut
Re: [pchapman] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

pchapman wrote:
f94sbu wrote:
Lets do the math to see if your logic holds together:
[..] This means that you were subjected to 128 - 192 G just prior to the cutaway.

Come on... even many students find out that they can have a canopy "open with" just one full line twist... but they keep rotating underneath until they have a few more twists.

(Whether or not the jumper you were replying to actually had exactly 12 twists...)

RSL's might get to be more accepted if some of their proponents didn't scare others away by going so weird with the math and physics. CrazySmile

My bad, lets say that 6 of the twists were introduced during deployment and the other 6 after deployment. Thats still 64-96G of initial rotation. And it is another 3 seconds where the jumper did not do anything after the reserve was deployed (other than just watching the line twists get more and more severe.) I have a hard time understanding your point actually. People make all sorts of claims regarding RSL's and line twists, but if we dont use physics to tell things apart, we will never get closer to a common ground. All we will have is two groups of people telling that the other group is wrong on the basis of a few personal experiences. Which is kind of funny because in this thread we have had almost identical testimonies from spinning malfunctions where the outcome has been either no line twists at all or multiple line twists. Either someone is lying or the reality is not as simple as some might try to make it. I prefer the later and using physics to explain why both groups have made valid observations and why some of the conclusions are incorrect.
If you don't like physics arguments, please share with us how you would like to be convinced? Crystal balls and magic wands? Angelic


f94sbu  (D 16017)

May 14, 2013, 7:59 AM
Post #104 of 161 (3329 views)
Shortcut
Re: [crotalus01] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

crotalus01 wrote:
The RSL may or may not have factored into the linetwists - I dont know. I had one hand on each handle and was less than 1 second between the cutaway and reserve fire. I didnt look at my reserve cable to see if it was kinked after the fact. As stated I was well aware I was low and I just wanted a landable canopy over my head ASAP. However, the fact that the RSL -could- have caused the linetwists was definitely a factor in my decision to disconnect it. Another reason is that I do a lot of altitude hop and pops and CRW. Now that I am starting to do more RW I am considering reconnecting it (and since I retired the Sabre I think it very unlikely I will end up with that many broken lines again).
Edit - I was not advocating anyone to disconnect their RSL.

Fair enough. As I said, I respect your decisions to jump without an RSL and the CRW one seems like a perfectly valid one (I do not jump CRW so I have not done the maths myself). In your initial post, you made it fairly clear that your decision to jump without an RSL was based on your reserve ride with multiple linetwists and it just wasnt clear this was something you would advocate to others or keep to your self.


crotalus01  (B 28932)

May 15, 2013, 5:34 AM
Post #105 of 161 (3085 views)
Shortcut
Re: [f94sbu] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

It is strictly a personal decision and I was not and am not advocating anything, simply sharing my experience. Just for further clarification there was no spinning under my reserve - it was open and flying straight with twists from right above my neck all the way up. I believe it was 12 that I counted as I kicked them out but to be honest I was pretty fucking stressed at the time so it may have been more or less....but it was a lot, enough for my buddy to remark he had never seen that many on a reserve before.
Edit - I meant I was not twisting up under the reserve, it opened with the twists so obviously something caused the bag to spin as it came out.


(This post was edited by crotalus01 on May 15, 2013, 5:42 AM)


format  (B 15348)

May 15, 2013, 9:26 AM
Post #106 of 161 (2994 views)
Shortcut
Re: [f94sbu] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Please somebody move this whole RSL raving on another thread and leave this incident on facts


chuckakers  (D 10855)

May 15, 2013, 7:05 PM
Post #107 of 161 (2778 views)
Shortcut
Re: [pchapman] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

pchapman wrote:
Notice how the jumper chopping the spinning "mal" rotated 180 degrees in the 1.0 seconds from the chop....

Yes, and notice how the jumper's rig turns with him - as does the reserve as it deploys!!

Did we all forget that if the jumper doesn't turn fast, the rig and deploying components will just turn with him?


jumpinjackflsh  (B 27757)

May 15, 2013, 9:55 PM
Post #108 of 161 (2718 views)
Shortcut
Re: [format] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

I understand your issue.

Though the facts as known have been given.

The resulting rsl discussion was born out of the facts.

Sometimes it may not seem in-line with the topic but in this case it is.

We all know that a cutaway that low, is usually non-recoverable. When someone is equipped with an RSL or skyhook, the question remains, what happened.

In that line of thought, these discussions take the turns that they take.

I don't have an RSL or an AAD but I can say, this discussion has me wanting to install an RSL, period. I'll take line twists on my reserve any day vs not having a reserve.

Though I'll close by saying, cutting away at 300' I'm not sure an RSL or Skyhook would've prevented this.

I think it's also valid saying if you have an RSL, use it. For obvious reasons you'd disconnect "on the ground" or on approach if you see you'll have to cut away (building, tree, high winds, etc...). It's also obvious you wouldn't use an RSL in CRW where cutting away is a whole other set of rules.

Either way, at the end of the day, the discussion is valid. Anytime someone goes in, without getting a reserve over their head, discussing why can lead us down a few roads.


Terrible thing. BSBD


Jack


The111  (D 29246)

May 16, 2013, 12:53 PM
Post #109 of 161 (2472 views)
Shortcut
Re: [jumpinjackflsh] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

jumpinjackflsh wrote:
The resulting rsl discussion was born out of the facts.

It seems to me it was built around the speculation that the jumper attempted to detach his RSL in the air. That is not a known fact in this incident.


likearock  (D 24640)

May 16, 2013, 3:40 PM
Post #110 of 161 (2403 views)
Shortcut
Re: [The111] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

The111 wrote:
jumpinjackflsh wrote:
The resulting rsl discussion was born out of the facts.

It seems to me it was built around the speculation that the jumper attempted to detach his RSL in the air. That is not a known fact in this incident.

That was only part of the discussion I believe. Most of it had to do with the general question of whether or not the RSL should have been detached (regardless of when that detachment was done).


livendive  (D 21415)

May 16, 2013, 3:53 PM
Post #111 of 161 (2394 views)
Shortcut
Re: [jacketsdb23] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

I've had line twists on a reserve that could have resulted in two fatalities, but it was a rather unique situation and thus doesn't contradict the statistics.

In my case, I had three lines break at the cascades during opening, after which the rather long bits still connected to the risers sprung back in the opposite direction they had stretch, i.e. toward my student and I. The canopy began behaving quite poorly in rather short order, so I chopped it not realizing where those lines were. As the canopy went away, the lines were pulled taut across my throat and retarded the canopy departure just long enough to get the RSL-deployed freebag spinning. The number of linetwists we had was rather shocking...from the risers to the top, with the stabilizers close enough to high five each other if the slider wasn't in their way. Plus, in typical tandem fashion, what little flying the reserve was doing was of the stall-surge variety. This was somewhere in the neighborhood of 4500'. From there to 2000', I was unable to get us out of a single one of the twists. It was kick-spin-kick-stall-kick-spin-kick-surge-rinse-repeat. Completely exhausted and having tried every trick I'd ever heard of and some I hadn't, I looked down at around 2,000' to see if staff were likely to be calling a lifeflight or a coroner and found we were centered over a busy 4-lane freeway. I decided that keeping busy was preferable to just watching the asphalt and semi's get bigger, so went back to what I'd been doing. Suddenly, just a couple hundred feet later, I made progress on one twist...invigorated, I got us the rest of the way out in rather short order (after which my student's first words since leaving the plane were "thank you for saving my life!") and managed a stand-up landing. The funny way people were looking at me on the ground was a clue as to what had happened, but once I saw a mirror I understood. It's a pretty unlikely situation, but in my case, an extra second between chop and reserve would have likely made for a much less terrifying ride.

Blues,
Dave


mpreil  (D 17822)

May 16, 2013, 8:46 PM
Post #112 of 161 (2290 views)
Shortcut
Re: [jacketsdb23] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

jacketsdb23 wrote:
If you choose not to jump an RSL thats fine, I don't use one either. But its not because I'm afraid of going in on line twists with the reserve.....

RSL's work and have saved lives.

Not a criticism - but I'm really curious about your calculus of risk. Why don't you have an RSL? Don't tell me it's too windy at Byron and you may need to cutaway after landing, you can always disconnect the RSL while flying - I did it all the time when the winds were up.

You have a great attitude about safety and you understand the equipment as well as anyone I know - so why not have one? I'm curious what you see as the downside. If you ever have to chop after loosening your chest strap and find the reserve handle isn't where you expected, you might really find it useful.

Again, let me emphasize that I'm not trying to start an argument. I am really interested in hearing your thought process. If you don't want to answer here just say so, I'll stop by and talk to you over a beer some evening while I'm driving home from "the other place".


JohnMitchell  (D 6462)

May 16, 2013, 10:39 PM
Post #113 of 161 (2248 views)
Shortcut
Re: [livendive] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

HOLY FUCK!Shocked


airtwardo  (D License)

May 17, 2013, 8:23 PM
Post #114 of 161 (1899 views)
Shortcut
Re: [JohnMitchell] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

JohnMitchell wrote:
HOLY FUCK!Shocked


...and THEN some! Shocked


Kudos Dave for 'keeping your head' in a bad situation! Cool


likearock  (D 24640)

May 18, 2013, 5:58 AM
Post #115 of 161 (1800 views)
Shortcut
Re: [livendive] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

livendive wrote:
It's a pretty unlikely situation, but in my case, an extra second between chop and reserve would have likely made for a much less terrifying ride.

Great job, Dave, but to put it in perspective for this general discussion, you do fly a pretty high performance canopy, do you not? The tendency and speed of "spinning up" after cutting away a cross brace is different from that of other canopies.


(This post was edited by likearock on May 18, 2013, 6:04 AM)


dzjnky  (D 28727)

May 18, 2013, 7:19 AM
Post #116 of 161 (1769 views)
Shortcut
Re: [likearock] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

likearock wrote:
Great job, Dave, but to put it in perspective for this general discussion, you do fly a pretty high performance canopy, do you not? The tendency and speed of "spinning up" after cutting away a cross brace is different from that of other canopies.

Ditto on the great job, Dave!
@likearock - this was a tandem jump for Dave - I doubt it was on a "high performance canopy" - I am not aware of many cross-braced tandem canopies Wink


likearock  (D 24640)

May 18, 2013, 4:29 PM
Post #117 of 161 (1639 views)
Shortcut
Re: [dzjnky] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

dzjnky wrote:
likearock wrote:
Great job, Dave, but to put it in perspective for this general discussion, you do fly a pretty high performance canopy, do you not? The tendency and speed of "spinning up" after cutting away a cross brace is different from that of other canopies.

Ditto on the great job, Dave!
@likearock - this was a tandem jump for Dave - I doubt it was on a "high performance canopy" - I am not aware of many cross-braced tandem canopies Wink

Missed that - my bad! Smile


sebcat  (D 22826)

May 19, 2013, 12:17 PM
Post #118 of 161 (1431 views)
Shortcut
Re: [f94sbu] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

f94sbu wrote:
pchapman wrote:
f94sbu wrote:
Lets do the math to see if your logic holds together:
[..] This means that you were subjected to 128 - 192 G just prior to the cutaway.

Come on... even many students find out that they can have a canopy "open with" just one full line twist... but they keep rotating underneath until they have a few more twists.

(Whether or not the jumper you were replying to actually had exactly 12 twists...)

RSL's might get to be more accepted if some of their proponents didn't scare others away by going so weird with the math and physics. CrazySmile

My bad, lets say that 6 of the twists were introduced during deployment and the other 6 after deployment. Thats still 64-96G of initial rotation
How did you come up with those numbers?

We're talking about a human body revolving around its centre at about one, two revolutions per second after cut away, during the reserve deployment process. Just taking the figure skating analogy previously posted in this thread and applying it to this situation makes me wonder if your numbers are correct.

I don't think 12 line twists happening would be unlikely. Partly because, as previously stated, some/most of those twists would occur post-deployment.

I don't have an RSL (CRW). I believe in personal choice. I'm not opposed to RSL's and if anyone asked me I would recommend having one. But you're gonna have to show some calculations or I would second what pchapman wrote.


f94sbu  (D 16017)

May 20, 2013, 5:00 AM
Post #119 of 161 (1213 views)
Shortcut
Re: [sebcat] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Lets say that you create 6 line twists during your reserve deployment, that means that your body must have rotated 6 times around its axis during the time the reserve deployed. I just approximated the reserve deployment speed to the max time allowed for a reserve to deploy (In reality, I would expect most reserves to open quicker).
This gave me 2 revolutions per second.
In order for your body to rotate like this after cutaway, it must have been rotating with the same speed before the cutaway. The cutaway itself does not change how quickly the jumper is rotating around his bellybutton. During a spinning malfunction, you can model your body like the bellybutton is making a wide circle and the body itself is rotating around the bellybutton. Both will have the same revolutions per second.

The G-forces applied to a body moving in a circle can be calculated using: G = w^2 * r / 9.81 where w equals the rotational speed in radians per second and r equals the distance between the center of the rotation and the body itself. 9.81 is used to convert true acceleration (m/s^2) to the nominal value that you experience standing in the surface of the earth.

I have to admit that I made a mistake when I halved the number of line twists as I only halved the G forces. As the G-forces are proportional to the square of the rotational speed, the correct numbers should have been 32 - 48G for a rotational speed of 2 revolutions per second. Still a fairly respectable G force if you ask a fighter pilot or an astronautSmile. The analogy with a figure skater does not apply here as the center of gravity of the figure skater is not moving in a circle. The figure skater may be spinning very fast, but if you made the figure skater spin around a point 2 meters away from him/her, it would result in an immediate blackout .

Keep in mind that I have tried to skew all the numbers to get as low G-forces as possible. When I had a choice, I made the line lengths shorter and the rotational speed slower, I still get incredibly high G-forces. All I am trying to prove with this is that if line twists under a reserve is tightly coupled to a spinning main, the main would have to rotate much faster than a human would be able to sustain.

Your point about the line twists increasing after the deployment is fully noted, however, I do have to ask you why that matters? A jumper that is unable to stop themselves from spinning for lets say 3 seconds, under a fully deployed reserve, do you think that they are better off trying to stop the spinning while accelerating towards the earth with no canopy out?

Personally, I think that the twists/no twists under the reserve has a lot of other factors other than just the rotational momentum left from the spinning main. Cutting away, pulling silver and arching as hard as you can is probably a much better recipe for survival compared to cutting away, trying to get stable and then pull silver.Given that people are regularly cutting away from spinning mains with an RSL connected, without getting line twists makes me think that it is perfectly possible to do so.
The number of lives lost every year which could have been saved by an RSL makes me very concerned about the logic that some people use when they try to convince others why an RSL is dangerous. There are situations where the RSL is introducing trouble, but lets keep those separate from the situations that most skydivers find themselves in.


sundevil777  (D License)

May 20, 2013, 6:39 AM
Post #120 of 161 (1155 views)
Shortcut
Re: [f94sbu] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

In reply to:
your body must have rotated 6 times around its axis during the time the reserve deployed.

Have you ever had linetwists on a main? Was it because you were rotating?

The freebag can rotate due to the container giving it a kick while it is leaving, which is more likely if you aren't shoulder-level.


f94sbu  (D 16017)

May 20, 2013, 8:36 AM
Post #121 of 161 (1111 views)
Shortcut
Re: [sundevil777] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

sundevil777 wrote:
In reply to:
your body must have rotated 6 times around its axis during the time the reserve deployed.

Have you ever had linetwists on a main? Was it because you were rotating?

The freebag can rotate due to the container giving it a kick while it is leaving, which is more likely if you aren't shoulder-level.

Thats my whole point, thanks for missing it Cool. The standard reasoning against the use of an RSL is that a spinning main would give you line twists on the reserve. Now you are saying that there are other reasons why you might get line twists on the reserve? Those are rarely mentioned by people who had the line twists. With my physics argument, I just showed that the number of line twists that people are describing is simply not possible to create with your rotational momentum _alone_. You just pointed out a factor that could make a difference regardless the use of an RSL. And thats my whole point. Dont blame the line twists on the spinning main.

Regarding your main vs reserve comparison, keep in mind that the reserve freebag is stowless, it doesnt have a kill line, the pilot chute is more or less unused and the riser covers are open. (If you cutaway from a spinning main). I dont have any data for this, but I get a feeling that frequency of reserve line twists are lower than the frequency of mains with line twists.


Ron

May 20, 2013, 1:22 PM
Post #122 of 161 (986 views)
Shortcut
Re: [f94sbu] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Quote:
Thats my whole point, thanks for missing it Cool. The standard reasoning against the use of an RSL is that a spinning main would give you line twists on the reserve. Now you are saying that there are other reasons why you might get line twists on the reserve?

An unstable main deployment can give you line twists on your main... The same can also give you line twists on your reserve. And flipping after a chop is being unstable.

The wind hitting your main bag can spin it up... The same for your reserve. And flipping or spinning after a chop can put the wind on your back.

If you are sideways or flipping when you deploy your main, you risk a malfunction.... The same thing applies to your reserve.

There is no doubt that having something out is better than going in at full speed... But there is also little doubt that it is better to be stable when you deploy a canopy.


f94sbu  (D 16017)

May 20, 2013, 2:16 PM
Post #123 of 161 (938 views)
Shortcut
Re: [Ron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Thank you very much for taking my quote out of contextFrown I never said that it is not possible to get a malfunction on the reserve, it was a rhetorical question. My point was that the number of reported line twists are higher than the number you would get from just rotating. Line twists on reserves are caused by a lot of other factors too (although they are minimized due to the design of the rig, the freebag etc.) However you cannot guarantee that they wont happen. When people argue that they are caused by RSLs deploying the reserve too fast after a spinning main, they have discounted a lot of other factors.


The111  (D 29246)

May 20, 2013, 4:09 PM
Post #124 of 161 (867 views)
Shortcut
Re: [f94sbu] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

f94sbu wrote:
32 - 48G for a rotational speed of 2 revolutions per second. Still a fairly respectable G force if you ask a fighter pilot or an astronautSmile.

If by "respectable," you mean will cause most people to either die, experience some semi-permanent injury (like a popped out eyeball for example), or at the very least black out... then sure. Considering the way a parachute harness attaches to the body and leaves the head completely unsupported, I suspect that any skydiver experiencing harness load at 30G+ will have his neck broken as a bare minimum. I also wouldn't be surprised if lines/canopy failed in multiple places at a ridiculous hypothetical load like 50G.

Those are insane G loadings that I suspect very few if any living skydivers (and humans period) have ever been exposed to. I'm not going to even begin to make an engineering analysis of the forces at work in a dynamic situation like this, but whatever the equation is, it's very unlikely to commonly result in such a high loading on a human body.


(This post was edited by The111 on May 20, 2013, 4:10 PM)


f94sbu  (D 16017)

May 21, 2013, 1:18 AM
Post #125 of 161 (699 views)
Shortcut
Re: [The111] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Quote:
Those are insane G loadings that I suspect very few if any living skydivers (and humans period) have ever been exposed to. I'm not going to even begin to make an engineering analysis of the forces at work in a dynamic situation like this, but whatever the equation is, it's very unlikely to commonly result in such a high loading on a human body.

That's my point. When someone says "Witnesses estimated the rotation to be 2 revolutions per second", the above G-forces would be the result. All I am trying to prove with my logic is that no one is able to rotate that quickly without dying.


Ron

May 21, 2013, 8:22 AM
Post #126 of 161 (1178 views)
Shortcut
Re: [The111] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Quote:
If by "respectable," you mean will cause most people to either die, experience some semi-permanent injury (like a popped out eyeball for example), or at the very least black out... then sure. Considering the way a parachute harness attaches to the body and leaves the head completely unsupported, I suspect that any skydiver experiencing harness load at 30G+ will have his neck broken as a bare minimum. I also wouldn't be surprised if lines/canopy failed in multiple places at a ridiculous hypothetical load like 50G.

Those are insane G loadings that I suspect very few if any living skydivers (and humans period) have ever been exposed to. I'm not going to even begin to make an engineering analysis of the forces at work in a dynamic situation like this, but whatever the equation is, it's very unlikely to commonly result in such a high loading on a human body.

You are right, 32-48G would be devastating if not flat out unsurvivable. Most people, without training/experience, lose it at about 5G.

In 1998 the racing aircraft Voodoo Chile lost a trim tab and the aircraft hit over 10G's rendering the pilot unconscious.
When the same thing happened to The Galloping Ghost in 2011 the NTSB thinks the pilot had 17G's. In both cases both pilots passed out and that was MUCH less than the quoted 32-48G.


ChrisD  (No License)

May 21, 2013, 8:35 AM
Post #127 of 161 (1169 views)
Shortcut
Re: [Ron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Smile

You are right, 32-48G would be devastating if not flat out unsurvivable. Most people, without training/experience, lose it at about 5G.


I wuoold add most loose something, wheatehr it be their lunch or nausua at about 1 g.


What did Gerado loose it at?

It was on Utube,...
C
Angelic


Ron

May 21, 2013, 9:30 AM
Post #128 of 161 (1147 views)
Shortcut
Re: [ChrisD] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Quote:
I wuoold add most loose something, wheatehr it be their lunch or nausua at about 1 g.

You are sitting at 1G right now.... Almost all of us are. Wink


ChrisD  (No License)

May 21, 2013, 9:41 AM
Post #129 of 161 (1135 views)
Shortcut
Re: [Ron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Thanks for the correction, Smile the point being we are not all that immune to increased g forces.

You know where you stand on this issue because you have lived thru this kind of thing, most people have not, and most people overestimate their g tolerance!

He appeared to be in great shape, was this a factor,..???


Certianly we all could do with a bit more physical conditioning, this is most likely the best defence against g forces that can overwhelm most of us???
C


format  (B 15348)

May 21, 2013, 11:50 AM
Post #130 of 161 (1086 views)
Shortcut
Re: [Ron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

"A hard slap on the face may briefly impose hundreds of g locally but not produce any real damage; a constant 16 g for a minute, however, may be deadly." - Wikipedia
In reply to:
In 1998 the racing aircraft Voodoo Chile lost a trim tab and the aircraft hit over 10G's rendering the pilot unconscious.
In 2008 I've cutaway from ~10G spin. If it lasted 1-2 seconds, I would black out but that was ~0.3sec effort to bring arm up to a handle.. 8-10 inches, fascinating hard but doable.
In 2006 reserve slammed me so bad, I had to help my head (neck) when laying down or getting up, for a month. Black flesh under legstraps, chest pain. Can't even start to calculate G's on that one.
My point is clear, I hope. Time spent under G-force is essential.. too.


Ron

May 21, 2013, 12:30 PM
Post #131 of 161 (1056 views)
Shortcut
Re: [format] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Quote:
In 2008 I've cutaway from ~10G spin.

How do you know it was a 10G spin... You have a G meter on you?

Most humans can't stand 5G+ for any real length of time. But yes, for a few milliseconds very high G forces can be tolerated.... In the majority of cases 10+ G's, conscious times are measured in *fractions* of a second.

If you had a 10G malfunction.... Well the average humans arm is about 6.5% of total body weight.... So if you are 180#'s about 11 pounds. 11 X 10G is 110 pounds. Can you curl 110 pounds with one arm? If not... then I would re-guess your G limit.

And how do you know it took you 0.3 seconds to chop? Because if you were able to bring a hand up to the handle, grab it, peal it, and pull it in 0.3 seconds.... You should have been a gun fighter.

Your point about G times is valid.... But you are discussing milliseconds, faster than a human can react. And the idea that you stayed awake during an unexpected 10G malfunction that occurred in less than 0.3 seconds, and managed to perform a cutaway in those conditions in 0.3 seconds is questionable.


pchapman  (D 1014)

May 21, 2013, 12:56 PM
Post #132 of 161 (1043 views)
Shortcut
Re: [f94sbu] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

f94sbu wrote:
When people argue that they are caused by RSLs deploying the reserve too fast after a spinning main, they have discounted a lot of other factors.

Line twists are a heck of a lot more likely though if one is deploying unstable than stable. That's whether it is due to body rotation, catching on the container, bag catching the wind unevenly, etc.

So the line twists may not be "caused" by the RSL 100% of the time, but the percentage is probably pretty high I figure -- compared to getting stabler first... if the ground isn't in the way in the meantime.

(And of course, this is the % within the cases of line twists, not % of all deployments.)

(P.S. - Two days ago I chopped for the first time in about 5 years . No RSL on my Racer. Not spinning though. I was low, so both hands moved pretty much simultaneously, and would have even if I had been spinning. I might as well have been using an RSL! Tongue)


format  (B 15348)

May 21, 2013, 1:34 PM
Post #133 of 161 (1024 views)
Shortcut
Re: [Ron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Ron wrote:
-How do you know it was a 10G spin...
-Because if you were able to bring a hand up to the handle, grab it, peal it, and pull it in 0.3 seconds...
It is my assessment based on line trim, risers, spinning, my perception of time and math. Prior to cutaway, hands were 'up' and whole spinning ordeal took ~3.5 seconds. Last 300 milliseconds isn't really that fast.. and there was no handle pealing.
Take it as is or don't. It is my view of my experience, can't prove it and I certainly won't feel bad or wrong.

As for RSL.. I don't believe I would end up half rolled in reserve bridle if I didn't have one.


f94sbu  (D 16017)

May 21, 2013, 2:42 PM
Post #134 of 161 (983 views)
Shortcut
Re: [format] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Quote:
As for RSL.. I don't believe I would end up half rolled in reserve bridle if I didn't have one.

Keep in mind that a spinning main would send your body rotating around your belly button, not rolling around your spine. Even if the reserve pc launches straight down, the only reason for you getting rolled up is that it is catching air and flying past you. If you arch and roll in the opposite direction during deployment, I can see how you might get rolled up. Without the RSL, what would your strategy be to avoid getting rolled up? Making sure that you face the ground before deploying your reserve? What if you are low?
I have been cutting away from a wildly spinning main once and I have to admit that I found it embarrassingly hard to get stable (this was a chop at 4000 feet so I knew I had time). Had this been lower, I would have had to deploy my reserve even though I knew I was facing the wrong direction.
(FWIW, I once made the silly decision to remove the RSL velcro on my rigg, that's why I jump without one in case you wonder. My next rigg will have a Skyhook, that's for sure)


Ron

May 21, 2013, 3:26 PM
Post #135 of 161 (963 views)
Shortcut
Re: [f94sbu] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Quote:
Without the RSL, what would your strategy be to avoid getting rolled up? Making sure that you face the ground before deploying your reserve? What if you are low?

Then you do not take a delay and you are no worse off than if you had an RSL deploy you.

And yes, I have done this.

https://www.youtube.com/watch?v=Liq4HYJZaho

I was below 1000 feet. I knew where I was and I performed my emergency procedures based on that information. Cutaway, roll belly to earth - reserve pull.

If you do not know how high you are, then you do not take a delay... just like an RSL. If you are unsure, then you do not take a delay.... just like an RSL. If you can't get stable quickly, then you pull anyway.... just like an RSL.


(This post was edited by Ron on May 21, 2013, 3:30 PM)


chuckakers  (D 10855)

May 21, 2013, 4:05 PM
Post #136 of 161 (936 views)
Shortcut
Re: [Ron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Ron wrote:
Quote:
In 2008 I've cutaway from ~10G spin.
Can you curl 110 pounds with one arm? If not... then I would re-guess your G limit.

Not agreeing with the poster on G's, but also not in agreement with the above statement. There's a big difference between curling a weight in the gym and making a movement under duress.

In a cutaway situation, a jumper will use several muscles to raise the arm if necessary, not just the bicep.

And let's forget about "super human strength" which is quite common among people in do-or-die situations.


chuckakers  (D 10855)

May 21, 2013, 4:14 PM
Post #137 of 161 (932 views)
Shortcut
Re: [Ron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Ron wrote:
Quote:
Without the RSL, what would your strategy be to avoid getting rolled up? Making sure that you face the ground before deploying your reserve? What if you are low?

Then you do not take a delay and you are no worse off than if you had an RSL deploy you.

And yes, I have done this.

https://www.youtube.com/watch?v=Liq4HYJZaho

I was below 1000 feet. I knew where I was and I performed my emergency procedures based on that information. Cutaway, roll belly to earth - reserve pull.

If you do not know how high you are, then you do not take a delay... just like an RSL. If you are unsure, then you do not take a delay.... just like an RSL. If you can't get stable quickly, then you pull anyway.... just like an RSL.

You rode a spinning mal for 20 seconds and rode a reserve for 7. Any more time "rolling belly to earth" and that wouldn't have been a reserve ride at all. Unsure


Ron

May 21, 2013, 4:49 PM
Post #138 of 161 (914 views)
Shortcut
Re: [chuckakers] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Quote:
You rode a spinning mal for 20 seconds and rode a reserve for 7. Any more time "rolling belly to earth" and that wouldn't have been a reserve ride at all.

1. I knew exactly where I was.
2. Read the description to see why I road it for so long.
3. It worked out fine.

As for the claims on strength.... Fear does not change physics. Yes, there are other factors but a 10G developed spin would require you to lift ~ 110 pounds to reach the cutaway.... Adrenalin or not, the chances of doing that in 0.3 seconds when you were surprised at the start is minimal.... Again, physics do not change.


sundevil777  (D License)

May 21, 2013, 5:57 PM
Post #139 of 161 (878 views)
Shortcut
Re: [Ron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Ron wrote:
Quote:
You rode a spinning mal for 20 seconds and rode a reserve for 7. Any more time "rolling belly to earth" and that wouldn't have been a reserve ride at all.

1. I knew exactly where I was.
2. Read the description to see why I road it for so long.
3. It worked out fine.

As for the claims on strength.... Fear does not change physics. Yes, there are other factors but a 10G developed spin would require you to lift ~ 110 pounds to reach the cutaway.... Adrenalin or not, the chances of doing that in 0.3 seconds when you were surprised at the start is minimal.... Again, physics do not change.

You figured that 110 pounds based on the entire arm weight placed at the end of the arm, correct? It would really only be the lower arm weight placed at the c.g. of the lower arm, which could mean a very different number.


sundevil777  (D License)

May 21, 2013, 5:58 PM
Post #140 of 161 (876 views)
Shortcut
Re: [Ron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Cutting away below 1k should not include taking the time to roll belly to earth.


Ron

May 21, 2013, 6:10 PM
Post #141 of 161 (871 views)
Shortcut
Re: [sundevil777] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Quote:
Cutting away below 1k should not include taking the time to roll belly to earth.

Your opinion... Maybe valid. But I have video evidence that it can be done. If I had pulled immediately and rode my reserve wrapped around my body till impact.... Would you say I did the right thing?

I am pretty happy with not dying and I can't see how I would do a single thing differently given the same situation.

And as for the arm... Yes, the weight would be less that 110. I don't know how much the jumper weighed, what his percentage of fat is... Or a whole bunch of other factors.

You want better math? Do it yourself.

But mine was close enough to show that a guy with a surprise malfunction didn't cut away a 10G malfunction in 0.3 seconds.


freakyrat  (D 12700)

May 21, 2013, 6:11 PM
Post #142 of 161 (869 views)
Shortcut
Re: [wmw999] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

I'm with you Wendy. I cutaway from my wildly spinning Stiletto without an RSL and pulled my reserve and it opened perfectly even after getting slung backwards on the cutaway.


chuckakers  (D 10855)

May 21, 2013, 7:11 PM
Post #143 of 161 (844 views)
Shortcut
Re: [Ron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Ron wrote:
Quote:
You rode a spinning mal for 20 seconds and rode a reserve for 7. Any more time "rolling belly to earth" and that wouldn't have been a reserve ride at all.

1. I knew exactly where I was.
2. Read the description to see why I road it for so long.
3. It worked out fine.

As for the claims on strength.... Fear does not change physics. Yes, there are other factors but a 10G developed spin would require you to lift ~ 110 pounds to reach the cutaway.... Adrenalin or not, the chances of doing that in 0.3 seconds when you were surprised at the start is minimal.... Again, physics do not change.


I did read the description. I guess I should have made that clear.

My point wasn't about riding it, it was about taking time to go belly to earth after a chop from a rapidly descending mal at a dangerously low altitude. That was just plain dumb, and dumb luck that your timing (assuming that's really what it was) gave you a reserve ride at all.

You seem to like math, so please take us through your logic. Are you really trying to tell us you can calculate your minimum reserve activation altitude (at an unknown descent rate, mind you) to have a 7 second reserve ride rather than a 9 second one - or 5 - or 1 - or none at all? Good luck with that.

I don't judge jumpers who live through any jump, but I do challenge poor logic and your reply clearly indicates you thought you had the timing down to a split-second science and that's ludicrous on its' face.

Even if you thought you did, you failed to remember that you can't predict the exact elapsed time of any reserve deployment. Add a single second to that deployment and your argument becomes fatally incorrect.

Logic fail - unless you are immune to everything but kryptonite.

As for your assertion that "fear does not change physics", you fail again. The measurement of human strength is not a number on a blackboard or a comparison based on a trip to the gym, and your G-force numbers were made up in your head anyway. A person's strength capacity under routine conditions isn't a fraction of what it is under duress. This has been demonstrated repeatedly in real-world conditions, from soldiers operating in extreme environments without nourishment for extended periods and still mustering the go-juice to perform like top athletes to average people lifting vehicles off of trapped victims, the evidence of people having seemingly impossible strength is long-standing and well documented. If you think you can argue with factual history, go for it.

You are right about one thing, though. It all worked out fine. It left you available to explain your madd skillz to others.

Getting stable after a cutaway is great. Pulling a reserve whether stable of not is better. Statistics bear that out.


(This post was edited by chuckakers on May 21, 2013, 7:33 PM)


airtwardo  (D License)

May 21, 2013, 8:57 PM
Post #144 of 161 (806 views)
Shortcut
Re: [Ron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Ron wrote:
Quote:
In 2008 I've cutaway from ~10G spin.

How do you know it was a 10G spin... You have a G meter on you?

Most humans can't stand 5G+ for any real length of time. But yes, for a few milliseconds very high G forces can be tolerated.... In the majority of cases 10+ G's, conscious times are measured in *fractions* of a second.

If you had a 10G malfunction.... Well the average humans arm is about 6.5% of total body weight.... So if you are 180#'s about 11 pounds. 11 X 10G is 110 pounds. Can you curl 110 pounds with one arm? If not... then I would re-guess your G limit.

And how do you know it took you 0.3 seconds to chop? Because if you were able to bring a hand up to the handle, grab it, peal it, and pull it in 0.3 seconds.... You should have been a gun fighter.

Your point about G times is valid.... But you are discussing milliseconds, faster than a human can react. And the idea that you stayed awake during an unexpected 10G malfunction that occurred in less than 0.3 seconds, and managed to perform a cutaway in those conditions in 0.3 seconds is questionable.

A few years back I had an opening so hard it broke a riser...

Of course it gave me quite a jolt, and there was a lot of harness bruising that followed - but I didn't seem to have any physical effects 'during' the opening.

Granted it was just a fraction of a second & I'm glad I didn't have cameras on...but I wonder what the G load actually was during that riser failure.

Someone told me they figured it to be in the 27-30 range. I don't know if that's accurate or how the figured it, but it sure got me thinking!




~On the other G load discussion;

A good friend use to have an Extra 300, he was a top notch airshow pilot and was actually the guy who signed other pilots off for aerobatic maneuvers at airshows.

He used to win a lot of bets with military pilots who'd claim high G tolerance, especially F-16 drivers. Some of those guys would brag 9 and 10 G turns without a problem.

My buddy would take 'em up in the Extra and knock them out usually around 5 or 6 G's. There's a huge difference between a reclined F-16 seat with a pressure suit on...and that up-right lawnchair they bolt in an Extra!

I made it to 5G's once with him but that was because he showed me how to breath right and 'grunt' the midsection - slowing blood loss. 3's in a tight turn for 3-4 seconds and I'd usually get tunnel vision and start graying out.

I don't think most people understand what is really like when in my case I'd go from weighing 220 pounds..to 1100 pounds!

Adrenaline or not...I was just staring at my hands, fascinated that no matter what I did - they weren't moving. Crazy


Ron

May 22, 2013, 12:04 AM
Post #145 of 161 (766 views)
Shortcut
Re: [chuckakers] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Quote:
That was just plain dumb, and dumb luck that your timing (assuming that's really what it was) gave you a reserve ride at all.

I say it would have been dumb to pull the reserve on my back while spinning. Like I asked the other guy, if I had pulled on my back and wore the reserve wrapped around me till impact.... Would you have said I had done the right thing?

Quote:
You seem to like math, so please take us through your logic. Are you really trying to tell us you can calculate your minimum reserve activation altitude (at an unknown descent rate, mind you) to have a 7 second reserve ride rather than a 9 second one - or 5 - or 1 - or none at all? Good luck with that.

Again, read about it on youtube.... Or you can do a search here, I wrote a long detailed explanation.

As for your claim that I can't do the math:
1. I don't need math to know that I am at an altitude high enough to deploy a reserve.... I just need to know I am ~750 feet.

2. I clearly can do it, I did and I have the video proof.

Quote:
As for your assertion that "fear does not change physics", you fail again. The measurement of human strength is not a number on a blackboard

Fail. Physics is physics. You can claim you are the hulk if you like, and yes, when in duress adrenalin does give a strength boost... But that is also physics, not the voodoo you seem to support

Quote:
I don't judge jumpers who live through any jump,

Ha, bullshit. That is all you have done. Good thing your opinion does not mean as much to me as my life.


format  (B 15348)

May 22, 2013, 6:22 AM
Post #146 of 161 (697 views)
Shortcut
Re: [Ron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Ron, after one hour analysinig your video, it seems to me that you've took a 19 seconds spinning ride while at stady 5.7 g-force. 5.7g most of 13 spins and prior to cutaway - 5.86g. Photo explains the math behind it.
I'm not surprised by those digits. There are factors to it, like vertical dive, off center rotation and others which I know nothing about and I guess those would lower the actual G's but this is the way I've got mine 10 (as I said, I wouldn't last 1-2 secs).
Attachments: Spin speed calculation.jpg (166 KB)


unkulunkulu  (C License)

May 22, 2013, 12:25 PM
Post #147 of 161 (611 views)
Shortcut
Re: [format] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

why are you assuming the center of rotation to be at the top of the lines? I would guess it is much closer to the jumper as the mass of the jumper+h/c+reserve is much bigger than that of the main and the fact that the aerodynamic force that rotates the system is applied to the main (big lever-arm distance to the center of mass).


(This post was edited by unkulunkulu on May 22, 2013, 12:28 PM)


SethInMI  (A 47765)

May 22, 2013, 4:59 PM
Post #148 of 161 (532 views)
Shortcut
Re: [format] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

format wrote:
Ron, after one hour analysinig your video, it seems to me that you've took a 19 seconds spinning ride while at stady 5.7 g-force. 5.7g most of 13 spins and prior to cutaway - 5.86g. Photo explains the math behind it.
I'm not surprised by those digits. There are factors to it, like vertical dive, off center rotation and others which I know nothing about and I guess those would lower the actual G's but this is the way I've got mine 10 (as I said, I wouldn't last 1-2 secs).

You took the long way to get the angular rotation, it is just 2*pi/1.48 sec.

The math looks right to me, though I agree with unk, I replayed the video and it appears to me the rotation point is just above the slider. At that high rotation rate, the radius makes a huge difference, if the rotation point is 1m down the lines, this brings the g force closer to 3.6.

Nice example of spinning body after a cutaway. Ron cuts away and then does several rotations around his own center of mass.


format  (B 15348)

May 22, 2013, 5:23 PM
Post #149 of 161 (524 views)
Shortcut
Re: [unkulunkulu] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

In reply to:
why are you assuming the center of rotation to be at the top of the lines? I would guess it is much closer to the jumper as the mass of the jumper+h/c+reserve is much bigger than that of the main and the fact that the aerodynamic force that rotates the system is applied to the main (big lever-arm distance to the center of mass).
It's a basic theoretical model which seemed most logical - considering parachute wing as rigid and rotating around axis on top the vertical lines (in this case A1). I would place axis at the top of the wing or even more up but that would only increase already high (to grasp) g-forces.
I don't see connection between wing or jumper's mass with it but if there is one, someone will explain.

This is the most chaotic thread discussion I've seen in a while.
Should be anywhere but here.

to SethInMI: you're right, as I said before, it's one of many variables I know nothing about


(This post was edited by format on May 22, 2013, 5:33 PM)


Ron

May 22, 2013, 8:45 PM
Post #150 of 161 (458 views)
Shortcut
Re: [SethInMI] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Quote:
The math looks right to me, though I agree with unk, I replayed the video and it appears to me the rotation point is just above the slider. At that high rotation rate, the radius makes a huge difference, if the rotation point is 1m down the lines, this brings the g force closer to 3.6.

I could buy 3.6G's.... But having been the guy in question I don't think it was much higher. I'll admit it was years ago, but I have some exp with G's since I fly acro and regularly do 3-4G's every weekend I can.

I can't buy into 5.6G's.... Mainly because that is a hell of a lot more G than people think, and I have seriously doubts that I would have been awake after almost 6G's for 20 seconds.

Quote:
Nice example of spinning body after a cutaway. Ron cuts away and then does several rotations around his own center of mass.

Yep, and maybe I should have mentioned this before.... I didn't try to get *stable*. That IMO is a bad idea in most case. What I did do is make sure I was *belly to relative wind*. Two vastly different cases.

Ill give my opinion and then leave... The human body has basically three axes it can rotate on.... Pitch (head over feet), roll, and yaw (like a center point turn). IMO, two of those are a really big deal for parachute deployment: Pitch and roll can trap the PC or catch part of the deploying parachute. Yaw on the other had is bad, but will most likely result only in line twists (which I had on my reserve on this jump). I can find very few cases of line twists on a reserve being fatal, although I do know of one case off the top of my head. However, I can find many examples of pitch or roll causing an issue.

Given the choice and the time.... I will try and stop pitch and roll before deploying a reserve. Yaw is not as important, and again IMO, the most difficult to stop.

There is also no doubt that it is better to pull a reserve before impact, and there is no doubt that it is better to pull a reserve than spend time trying to get *stable*...... I just think that given the time that it is better to spend that half second to minimize pitch and roll before deploying a reserve.

You guys have better video tools than me (and it seems more time).... How long would you estimate I took from chop to pull? Me, I'd say less than a second as a guess.


format  (B 15348)

May 22, 2013, 10:48 PM
Post #151 of 161 (735 views)
Shortcut
Re: [Ron] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

In reply to:
How long would you estimate I took from chop to pull?
1.84 sec from canopy distortion (chopped) to first sign of red (reserve exiting freebag).
Can't see actual pull so I'll say it took you less then 1.5 and more than 1 sec.


unkulunkulu  (C License)

May 23, 2013, 12:54 PM
Post #152 of 161 (627 views)
Shortcut
Re: [format] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

format wrote:
I don't see connection between wing or jumper's mass with it but if there is one, someone will explain.
Sorry, but if you don't see a connection between "center of mass" and rotational movement, maybe you should not share your computations of g forces and other things about physics? I mean, really, make an experiment: take a pencil and rotate it by quickly knocking it on its end, it will probably rotate around it's center. Then glue something to the other end of the pencil and make the same knock. It will rotate around a point much closer to the glued mass. It's called the "center of mass", very important thing for rotational movement and other things :)


(This post was edited by unkulunkulu on May 23, 2013, 12:57 PM)


format  (B 15348)

May 23, 2013, 1:30 PM
Post #153 of 161 (603 views)
Shortcut
Re: [unkulunkulu] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

unkulunkulu wrote:
format wrote:
I don't see connection between wing or jumper's mass with it but if there is one, someone will explain.
Sorry, but if you don't see a connection between "center of mass" and rotational movement, maybe you should not share your computations of g forces and other things about physics? I mean, really, make an experiment: take a pencil and rotate it by quickly knocking it on its end, it will probably rotate around it's center. Then glue something to the other end of the pencil and make the same knock. It will rotate around a point much closer to the glued mass. It's called the "center of mass", very important thing for rotational movement and other things :)
Thank you for contributing to better understanding of g-forces involved. It is more clear to me now and you are right.
Please continue, eventually a simple way will arise for easy G-calculation that no one would question.




ChrisD  (No License)

May 23, 2013, 8:39 PM
Post #155 of 161 (522 views)
Shortcut
Re: [Festus] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

thanks festus!

My favortie actor from Ripcord!!!

Angelic


SethInMI  (A 47765)

May 24, 2013, 5:08 AM
Post #156 of 161 (451 views)
Shortcut
Re: [unkulunkulu] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

unkulunkulu wrote:
if you don't see a connection between "center of mass" and rotational movement, maybe you should not share your computations of g forces and other things about physics?

Don't get carried away unk. The center of mass of the system is important, but keep in mind we are not in a vacuum, and the aerodynamic forces acting on the parachute are more significant in finding the rotation point of the system. The rotation point of a diving canopy is usually far above the top skin. It is only for situations where the system is rotating scary fast that the rotation point moves below the top skin of the canopy, and it NEVER gets all the way to the center of mass of the system, somewhere in the torso of the jumper.

Seth


Premier billvon  (D 16479)
Moderator
May 24, 2013, 12:58 PM
Post #157 of 161 (362 views)
Shortcut
Re: [unkulunkulu] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

>I mean, really, make an experiment: take a pencil and rotate it by quickly knocking it
>on its end, it will probably rotate around it's center. Then glue something to the other
>end of the pencil and make the same knock. It will rotate around a point much closer
>to the glued mass.

Now put an airfoil on the other end and repeat, this time spinning very fast. Its center of rotation will change, and it will depend on speed.


chuckakers  (D 10855)

May 24, 2013, 2:02 PM
Post #158 of 161 (347 views)
Shortcut
Re: [format] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Don't bother, guys. Dood is clearly a genius. After all, only such a brilliant person could calculate a 7-second reserve ride like he did. He apparently even knew exactly how long his reserve would take to open. Wink

Fools die young - and damage the sport.


Premier wmw999  (D 6296)

May 24, 2013, 2:21 PM
Post #159 of 161 (335 views)
Shortcut
Re: [chuckakers] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

I've met Ron. He's neither a fool, nor (particularly) young. OTOH, it does sound calculated a whole lot more carefully than I would in the press of the moment.

Wendy P.


chuckakers  (D 10855)

May 24, 2013, 2:53 PM
Post #160 of 161 (320 views)
Shortcut
Re: [wmw999] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

wmw999 wrote:
I've met Ron. He's neither a fool, nor (particularly) young. OTOH, it does sound calculated a whole lot more carefully than I would in the press of the moment.

Wendy P.

Calculated carefully? Listen to his description of the incident. It's ludicrous.

He can do all the calculating he wants. The only difference between a 7-second reserve ride and death is nothing more than deployment time, and THAT can't be calculated with any regularity or accuracy by anyone.

THAT is foolish no matter what other positive attributes a jumper may demonstrate, and it's a ridiculous and dangerous message to send to other jumpers - especially the young sponges that take what more experienced jumpers say to heart.

Can you honestly say someone who believes they can calculate a 7-second reserve ride is anything other than a fool?


(This post was edited by chuckakers on May 24, 2013, 2:54 PM)


unkulunkulu  (C License)

May 24, 2013, 4:49 PM
Post #161 of 161 (284 views)
Shortcut
Re: [billvon] 8 May 2013 Fatality Skydive Deland [In reply to] Can't Post

Right, the lift of the canopy will change things. But we have to calculate the center, not just say "if we assume it at the end of lines, we get 10G", right? I don't know how to account for that, but I'm thinking :)



Forums : Skydiving : Incidents

 


Search for (options)