Basejumper.com - archive

The jumper on the left is Johny 9lives. We did a 2-way, holding hands through opening with both of us being PCAed. The cliff was a rock quarry in Rode Island. The town locals said it was 78 feet. Our landing was into deep clear water (thank goodness). 9lives chose to prime his Velcro and that is what you're seeing. I figure since we were getting a PCA, whatÕs the point of priming my Velcro, so I didnÕt. But hey, if a man wants to prime his Velcro, then thatÕs his business.

A couple different sites and a few days later, 9lives, Danny Koon and myself made it back to Cross Keys where they were having a boogie. At the end of the boogie the local fire department came out with a ladder truck and shot up a stream of water for swoopers to swoop under. 9lives decided he wanted to jump this fire truck ladder. At full extension, the ladder is 100 feet long. They leaned the ladder out a bit over the pond, making the exit altitude close to 80 feet. The exit point was over 3 feet of water. He kept asking me what I thought. I kept telling him 50/50. So we went up the ladder. Having just done the quarry jump a few days earlier, I learned a lot about the relationship between bottom skin inflation rate and anchor point tension strength (such as break cord strength or how hard one holds on to the PC during a PCA). When we reached the top of the ladder and looked over, I figured it was possible but it would be close. He wanted to do it and I knew the only way it would work is if he had an anchor point strength almost equivalent to his weight (155 pounds). Once he climbed over the rail and got in position, I unpeeled his shrivel flap, folded it in half and gripped it so it would pull out of the bottom of my grip. I told him he was all set, and he went quickly. I held onto that shrivel flap with every fiber of strength I had and I believe that for a moment, I held his whole weight in my hand. He did get very quick bottom skin inflation, and then full canopy pressurization. The canopy flew forward for a short canopy ride, and he landed in the three feet of water standing up for the most part and walked right out of the water without a scratch. If he had landed on hard ground, he probably would have walked away as well. In the end, I had just watch the lowest real BASE jump that I have ever seen or heard of, and my hand was completely numb for a while. We do have video of it and I will post an image in the near future. If anyone knows of a lower ÒrealÓ BASE jump, IÕd like to hear about it. The part that cracks me up, is that he not only jumped from a ladder, he BASE jumped from a vehicle, a truck. Unbelievable!!!

Hey Johnny, is that a tower is see reflecting in the water?

Can you elaborate?

Why did you believe that the anchor strength had to be 155 pounds?

It seems to me that such a strong grip on the PC would yield center cell strip, thereby slowing inflation. (I don't think this would have much effect on bottom skin expansion.)


I believe that there is video of a 63 foot jump on Fixed 2.

Zennie, yes there was a very small tower there.

Tom,
I don't have a whole lot of time right now to go into full detail (Trevor keeps me very busy), but I'll do my best to quickly elaborate for you.

You replied,
ÒIt seems to me that such a strong grip on the PC would yield center cell strip, thereby slowing inflation. (I don't think this would have much effect on bottom skin expansion.)"

My response,
From my experience through the 12 years I've been BASE jumping, I've noticed that the harder one holds on to the PC during a PCA, the faster the opening. I believe this is due to quicker bottom skin inflation, which results in an increase in canopy inflation rate (similar to the way my Super Mushroom packing technique works with a PC). Center Cell Strip is a result of too much snatch force (such as having too big of a PC at terminal). What causes center cell striping is that the cocoon is extracted too quickly from the container. Increasing the anchor strength on a S/L or PCA jump does not increase the snatch force. It does not result in the cocoon being extracted quicker, it just puts more tension on the lines and fabric once the parachute has reached full line stretch. This tension anchors the parachute system a moment longer, giving it that moment of more time to spread out before the jumper and parachute fall away from the anchor point. The more canopy you can get to spread out before the system breaks away from the anchor point, the more bottom skin is exposed and within a small fraction of a second the bottom skins grabs air, and that is bottom skin inflation. Obviously the less altitude lost during bottom skin inflation, the less altitude lost during the whole inflation process. Further more, the decrease in loss of altitude is exponential to the bottom skin inflation rate. I donÕt know the mathematical formula yet, but it has to do with acceleration during sub terminal freefall. Every moment of sub terminal freefall you lose more and more altitude as you accelerate, and that results in the exponential characteristic of it.

You asked,
"Why did you believe that the anchor strength had to be 155 pounds?Ó

My response,
Well, honestly, it was an educated guess at best. I actually am planning a series of test to gain some real data that will hopefully show just how much benefit is gained for every pound of increased anchor strength, and if there is a point when it doesnÕt increase the benefit (benefit being less loss of altitude).

I said,
ÒI had just watch the lowest real BASE jump that I have ever seen or heard of, and my hand was completely numb for a while.Ó

You replied,
ÒI believe that there is video of a 63 foot jump on Fixed 2.Ó

YouÕre right, there is a clip of that on fixed 2. IÕve watched it myself many times. That one is marginal. That jump could be made just as safe without a parachute. Jason noted in his video, that using a parachute was optional for that cliff jump, and if it had been over hard ground, that dude would have been seriously broken or dead. The PCA 2-way we did in Rode Island was just like that, only 78Õ. It was not a ÒrealÓ BASE jump. If the water had not been there, we would have been seriously messed up or dead, and people were jumping from the same exit point without parachutes and were just fine. So on that jump, the water was our final deceleration device. The jump Johny 9lives did from the fire truck ladder, was a ÓrealÓ BASE jump because the parachute opened and stopped his fall, completely inflated, and flew. If it had not opened, he would have been seriously injured or dead as it was over only 3 feet of water. A very ballsy move on his part. Common sense needs to be applied here, otherwise, I could static line from my roof into a pool and call that a BASE jump.

IÕm interested to know if anyone knows of a lower BASE jump using these guidelines.

Thanks for your input Tom.

So, do you think that a static line would yield faster overall inflation than a direct bag?


I'm not sure that's so obvious. Just for the sake of argument, picture a hypothetical deployment method that would create full cell pressurization simultaneously with bottom skin expansion, but take ten more feet than a PCA. I'd guess that cell pressurization on a PCA will take more than the ten extra feet.

Another hypothetical: Picture a canopy with a "perfect valve" bottom skin. Assume that the whole bottom skin is one giant (but perfect) one way valve. This theoretical canopy ought to expand top skin first, with the top skin pulling the bottom skin into place. I could also make a pretty good argument that it would be the fastest inflating canopy possible. But it would clearly lose more altitude prior to bottom skin expansion (which would follow top skin expansion) than a real world unvented canopy. So, this canopy would lose more altitude prior to bottom skin expansion, but still be "overall" inflated and flying sooner.

And a not so hypothetical: What about tailgates? Tailgated canopies achieve bottom skin expansion slower than non-tailgated canopies, but still achieve full inflation faster than non-tailgated canopies.

I guess what I'm driving at is that I'm not convinced that faster bottom skin expansion must necessarily lead to faster overall inflation.

I split this discussion of PCA, altitude and opening time (and some other stuff) off from the "You're a BASE jumper when..." thread.

It looks like it's diverging in interesting (and more technical) directions. If I get a chance I'll try to replicate it onto BLiNC, as well.

if anyone would like to see the video of the jump let me know where i can upload the file.

i swear i had nothing to do with suggesting the firetruck idea
edited to add: damn i forgot i was logged in as my GF! -payback462

Right on Tom, I enjoy a good brain storm. IÕll quote you and then respond so the readers can follow the conversation.

>ÒSo, do you think that a static line would yield faster overall inflation than a direct bag?Ó<

That is an excellent question Tom! I donÕt know for sure. IÕve seen it go both ways. Of course factors like canopy type, wing loading, wind direction and velocity, air density, and other factors, might affect the opening speed. If and when I do the test jumps, I will be sure to include some S/L vs D-bag experiments. If I had to make an educated guess, it would be that a S/L with a low anchor strength would lose more altitude than a d-bag. Whereas, a S/L with a high anchor strength would lose less altitude than a d-bag.


DEFINITION
In my previous post I mentioned: The more canopy you can get to spread out before the system breaks away from the anchor point, the more bottom skin is exposed and within a small fraction of a second the bottom skins grabs air, and that is bottom skin inflation. To simplify. My definition of bottom skin inflation is: When the bottom skin has expanded and has air pressure against it. So, bottom skin expansion is essentially the same thing as bottom skin inflation, with only a very small fraction of a second difference in timeÉso small, how could we measure it?


>ÓAnother hypothetical: Picture a canopy with a "perfect valve" bottom skin. Assume that the whole bottom skin is one giant (but perfect) one way valve. This theoretical canopy ought to expand top skin first, with the top skin pulling the bottom skin into place.Ó<

For this valve to work, doesnÕt it need bottom skin inflation? Even if it doesnÕt require bottom skin inflation, and can some how allow air in with the bottom skin folded up, the more the bottom skin is open, the more air can get through to the inside of cells and the top skin.


>Ó I could also make a pretty good argument that it would be the fastest inflating canopy possible. But it would clearly lose more altitude prior to bottom skin expansion (which would follow top skin expansion) than a real world unvented canopy. So, this canopy would lose more altitude prior to bottom skin expansion, but still be "overall" inflated and flying sooner.Ó<

What I would like is a canopy that packs itself.


>Ó And a not so hypothetical: What about tailgates? Tailgated canopies achieve bottom skin expansion slower than non-tailgated canopiesÉ.Ó<

I agree.


>ÓÉ. but still achieve full inflation faster than non-tailgated canopies.Ó<

I disagree. I have seen several times, a canopy open slower due to a tailgate (like if you wrap the rubber band too tight for a no delay or short delay jump). However, the tailgate increases your chance of an on heading opening, and on heading openings seem to pressurize cleaner and quicker than off heading openings. This is probably due to less distortion of the air inlets in the nose and the increase of forward airspeed during the inflation process.


Tom, when I do the test jumps, I will need some test jumpers. Let me know if youÕre interested.

So if you were doing a static line in this situation would you use thicker break cord? Like you figured that you should hold with 150 lbs...would you use 150 lbs break cord instead.

Tom mentioned center cell strip. BR's much maligned multi might help with that.

I think this is significant even for jumps that are over 80 feet. Say a 150 foot static line. Wouldn't you enjoy that much more saftey margin if you could work this out properly? Or how about that 150' object where you can't quit reach the landing area, you get flying higherybe you can make it...

Don't know.

I really disagree with that. You might be open higher with more tension on the anchor. I still doubt that, but it sounds like Johnny is going to do some empirical testing and let us know.

But using a higher tension anchor will certainly create more center cell strip, and hence degrade heading performance. If your goal is to get open and fly somewhere (as opposed to just getting open and landing), having good heading is going to be more important than having a (possibly) slightly higher opening. Any altitude you might gain from using an old school "grim death" PCA grip will, statistically, be lost in the riser and toggle corrections you need to make to fly in the correct direction.

Leaving aside improper application of the tailgate (i.e. too tight a rubber band, or girth hitching, or whatever), I really believe that a tailgated canopy will reach full pressurization sooner.

I don't think I am alone in this belief. Reading Dwain's Nose First Inflation article, I see that he comments: "if the canopy inflates nose first it will surge less, reach full pressurisation quicker and stress the brake lines less." (emphasis added).


Absolutely. I'd love to help out.

I agree that if you lose heading control of your opening and have to correct then you would indeed lose any altitude gains. BUT, don't you agree that by using a muti system you could minimze the center cell strip effect thus regaining the altitude gain?

In theory, yes. I haven't done any real research into it, but I think the theory is pretty sound. I don't see a downside to the multi on a PCA, and I can see plenty of upside.

Note for anyone reading this who doesn't know already: You should not use the multi sheath on a PCA jump, as per BR's owners manual section 4.4:

With the utmost sincerity,
I remain,
Gardner

Some of this is new territory that needs to be safely explored further. One danger I can think of, is if you use too strong of break cord, you could end up hanging off the exit point. So, do not start out using a break cord strength close to your body weight. Some more research needs to be done first.

When I told the story of the Ladder truck jump, I was doing just that, telling a story. Explaining how things happened and why. This has turned into a brainstorm or a debate out of control (what ever you want to call it), which can be a healthy thing. It just seems like we have strayed away from the story I was telling about one of the coolest jumps I have ever seen. I have attached some images of the jump. Please enjoy them.


This reminds me of something you said at Petronas last December. You were saying that a line over will not make your canopy spiral. I over heard this and thought for the safety of you and other's, I should inquire. I asked you why you would think that. You said because you had a line over and it did not spiral. I told you then, ÒEvery line over has a different configuration.Ó I hope you believe that.

Time in the sport is a huge factor when considering ones experience and knowledge. Through time, one learns from all that they see and hear. This helps give them solid knowledge.

I know for a fact, that the harder you hold on to a PCA, the faster the parachute will open. I have seen it with my own eyes (real life, not video) many, many times, both as a spectator to it and the person giving the PCA.

The basis of my study is to understand exactly why and to what point of adding anchor strength you would benefit. Also, at what anchor strength will there be no more additional benefit and perhaps even a negative effect (The extreme example, would be an anchor strength that results in you hanging off the exit point).

Tom, I am impressed with the knowledge you have gained in a short time, however, you still have much to learn in this sport. You are an asset to the BASE community; just make sure you are teaching solid information. I hope my words do not offend you as you do a great job here.


DonÕt take me the wrong way Tom, but you should know that what you are saying here makes no sense (unless you are using a hypothetical 40 foot static line). Let us define what Òcenter cell stripÓ is. I said the following in a previous post (post#4).

{Center Cell Strip is a result of too much snatch force (such as having too big of a PC at terminal). What causes center cell stripping is that the cocoon is extracted too quickly from the container.
Increasing the anchor strength on a S/L or PCA jump does not increase the snatch force. It does not result in the cocoon being extracted quicker, it just puts more tension on the lines and fabric once the parachute has reached full line stretch.}

In other words, that last two sentences mean: You will have the same snatch force using 40 pound break cord as you will using 100 pound break cord. Now if you had a hypothetical spring-loaded static line that will spring upward as the jumper exits, then you would have a higher snatch force.

Perhaps you think that any distortion of the center cell after full line stretch is the same thing as Òcenter cell stripÓ. It is not. Center cell strip is just exactly what it saysÉwhen the center cell is stripped off the packed canopy (cocoon). This happens when the opposing forces between the bridle and the jumper are high during container opening. The bridle yanks (snatches) the attachment point away from the jumper so fast that the heavier part of the packed canopy (cocoon) cannot keep up. In other words, the majority of the packed canopy stays in or closer to the pack tray, as the center cell is stretched vertically by the attachment point being yanked upward by the bridle. Whew!!! That was a mouthful.

To simplify:

Let us define an anchor, as that force, which pulls against the jumperÕs fall, causing the canopy to come out and play.

Let us create and define a new term called, Òextraction speedÓ. Extraction speed is how fast the anchor pulls the canopy out of the container. This speed is determined by the total force downward (jumpers fall rate and exit weight), minus movement of the anchor (like in the case of a pilot chute). If you got extra time on your hands Tom, how about figuring out a math formula for this.

My definition of Center Cell Strip is: When the center cell is stripped off the packed canopy (cocoon), as a result of an extraction speed that is too fast.

Whether you are falling away from 40 pound break cord or 100 pound break cord, the canopy is pulled out at the same speed and has the same amount of tension all the way up to full line stretch (even all the way up to the point where the 40 pound break cord gives.)

I do agree that higher anchor strength may cause some extra distortion to the noseÕs air inlets at full line stretch, but this is not the same thing as center cell stripping. It happens later in the opening process so the canopy is already spreading out and approaching bottom skin expansion.

A go and throw, would cause the slowest extraction speed (that I can think of right now). Its extraction speed is only slower than that of a S/L or PCA because the pilot chute moves with the jumper. A S/L or PCA also have a very slow extraction speed (unless you are using a hypothetical 40 foot static line or bridle).


I disagree with you. Based on my personal experience, a stronger anchor point (such as holding onto the pilot chute harder) will give the jumper significant altitude gain, which will far surpass the small amount of altitude lost in a minor toggle correction. The various combinations of variables will make it very difficult to determine at what point, with what configurations, the altitude gain is cancelled out by altitude lost from a heading correction. More testing needs to done to even give us an idea.

I would like to see those statistics and how they prove your point.

Tom, Johny 9lives had a tailgate for the ladder truck jump. We are using tailgates on all slider down/off jumps, so I do not understand why you are still debating this. I am all for a healthy debate, but you are going in circles. In post #8 the rest of my paragraph says:

{However, the tailgate increases your chance of an on heading opening, and on heading openings seem to pressurize cleaner and quicker than off heading openings. This is probably due to less distortion of the air inlets in the nose and the increase of forward airspeed during the inflation process.}

I do not disagree with the point you are trying to make. You are just skipping some factors in between. The tailgate promotes nose inflation first -- which promotes on heading opening -- which promotes less distortion in the nose and cleaner, more direct airflow into the cells -- which promotes faster pressurization of the canopy. Do we both agree here? Your statement is almost accurate but not quite. You would be more correct to say (which is safer in this case), A tailgated canopy has an increased probability of reaching full pressurization sooner.

The tailgate is one way to get the nose to inflate first. Another way, is to shut down the tail. I have video of some openings of mine, back before I used tailgates, that look like there is a tailgate being used. Either way, this results in a higher chance of an on heading opening. A canopy opening on heading should have a more direct airflow going into the nose than a canopy going off heading. Also, on heading openings will usually result in less distortion to the nose, which will allow more of that direct airflow into the cells.

I agree with Dwain's article. Especially the part where he says:



Dwain and I are on the same page, like we were on most things we discussed. I can think of a time when we disagreed on an issue. It was at the last Petronas event, concerning a jumper who spiraled onto the roof of the mall. After watching the video one time, I said it looked like he had a tension knot. Both Dwain and Slim adamantly disagreed with me. They thought because the slider had come down, it could not be a tension knot. I listen to their response, and quickly determined that a tension knot can occur within a single riserÕs line set. After explaining this to them, they still disagreed. Later that day, a zoomed in photograph, taken from another building, showed without a doubt, that it was indeed what I said it was (a tension knot).

My point is, even the best are not always right.



OK, I would love to have you there...you are on the load.

Blah, blah blah...OK Guys....Enough with the theories

Location: Moab

Date: Turkey Boogie

Object: 100ft cliff

Method: TARD vs DBAG vs Johnny's PCA vs Tom's PCA vs (if we can find a decent anchor point) static line single 80 lb breakcord vs double breakcord vs 3 wraps electrical tape Aussie style...

Let's play!

Spence

Definitely picking up an extra battery for my camera before then... Guess I should throw in a traction splint as well.

From the pics it looks like Johnny 9lives had almost a 90 offheading opening - was this right? Any idea why? Looks like he was in a position not to have to correct it anyways, so could fly in that direction for landing...
\
Rob Price

Very observant Rob. He had a right 70 degree off heading opening. He did a normal pack job for a slider down/off jump, using a tailgate, which normally promotes an on heading opening...on this jump it didn't. From what I saw in real life and from watching the video, there is no apparent center cell distortion. Yes, his off heading put him in a perfect landing spot. That was luck.

IMPORTANT NOTE:
You cannot completely control the opening due to random chance. (There is a way to steer the opening on a slider up jump, but that should be saved for another discussion.)

RANDOM CHANCE Ð Say you fold and pack your parachute absolutely perfect, and during opening your pack tray is absolutely flat and still, and the wind conditions are totally calm; you can still have an off heading opening (or tension knots) due to random chance. This is why. The way the air hits the fabric and lines of your parachute, and the way the fabric and lines react to that air is completely random.

We pack the way we due in this sport to encourage the fabric and lines to respond to the air a certain way, but the air is random and the response is random, and we cannot control it.

One more question. Can't tell from the pics - was this canopy vented? valved?

"IMPORTANT NOTE:
You cannot completely control the opening due to random chance. (There is a way to steer the opening on a slider up jump, but that should be saved for another discussion.)

RANDOM CHANCE Ð Say you fold and pack your parachute absolutely perfect, and during opening your pack tray is absolutely flat and still, and the wind conditions are totally calm; you can still have an off heading opening (or tension knots) due to random chance. This is why. The way the air hits the fabric and lines of your parachute, and the way the fabric and lines react to that air is completely random.

We pack the way we due in this sport to encourage the fabric and lines to respond to the air a certain way, but the air is random and the response is random, and we cannot control it. "

I have to respectfully disagree with you there, Johnny. The voodoo involved in "random" off headings initiated by the packjob is due to variation from the ideal configuration within our pack jobs. We vary slightly each time we pack. The way that the physical system (jumper, packjob, conditions, timing etc.) reacts is not random. It is very precisely defined by the laws of physics but the system is so large and complex that we haven't fully figured out the levers and triggers yet. I believe that the factors are indeed controllable. We just haven't found out how (yet). As the sport progresses and we reduce the variation we will inevitably move to a time where the configuration of a packjob is so consistant that it is no longer a contributor to an off-heading opening.

I'd hate to call off the dogs in the search to discover the perfect packjob. We're not there yet by any means. We're just a hell of a lot better than the old boys used to be.

Skin

On a side note...Why is it that every time I see a photo of you the pic is of your ass?

Stay safe.

While I see no reason to dispute what you're saying here, I thought the tailgate was developed as a reefing mechanism to prevent slider down/off lineovers.

You might be interested in reading this old post of Dwain's.

Johnny,

On a Direct Bag deployment, do you think that attaching the bridle attachment point of the canopy to something inside the D-bag will yield faster overall inflation?

I think we're just at a point where we're disagreeing on theory here, and we'd be better served to go out and do some test jumps to see what the actual end result is. But if you're right on the theory, we ought to include a set-up like the one I'm asking about (D-Bag with attachment inside), as I'd think that would be one of the fastest possible systems.

Another thought: What do you think of doing a static line quad/tard, where the free hanging canopy is attached to the exit by break cord (via the attachment point), and you jump past it, leaving it at the exit?

Dude, it sounds more like you wanted to address addition factors that contribute random chance to the BASE jump. The variances you are talking about are not intentional (right?), and therefore those different configurations, happen in a random way (unless you have simply perfected a less than ideal behavior), and can repeat a less than ideal configuration exactly the same way time and time again. Perhaps some day we can control these factors better, resulting in a perfect pack job every time. In my explanation, I eliminated these factors, to focus on the one thing that you will never be able control (at least not in this life), AIR!!!


Did you read that part?

Let us go to a molecular level. There is and will always be a part of the equation that you will never be able to control. Air molecules!!! The alignment of air molecule in one cube foot of air will be different than the alignment of air molecules in another cube foot of air. This is the nature of a gas. Air is matter in a gas form. If you understand physics, then why do you not understand this?

The way those air molecules bump into the fabric and lines during opening will always be different on every jump, because those air molecules will always be aligned differently within that section of air that the parachute is opening in.

(Unless it is the year 2250 AD and man has invented a chamber big enough to BASE jump in that will align gas molecules in a perfect array.) Instead of doing that, I think man should just build a bigger bridge.


Actually my post that you replied to, has a picture of me jumping from a helicopter at Squaw Valley during the Blade Running 1998 event, where you can see my face but not my ass. If you are a guy, I would appreciate it, if you would not focus on my ass. Thanks!

I do not know.
One big advantage to a d-bag, is that the canopy comes out of its containment device sooner, which allows it to spread out quicker. Keeping this in mind, it might be a mute point to anchor it. A danger that I can think of right now is: if the canopy is anchored to close to the exit point, it would have more chance of snagging on the object. Maybe we could put some kind of length between the attachment point and the anchor inside the d-bag. We will have to test that, and you can be the guinea pig if you want to.


What the heck!! What kind corn pops have you been eating Tom? Just kidding.

If you were to use a short S/L, it may result in a higher off heading opening, with an increased chance of object strike. We could call that a tard to the second power.

On a roll over (McConkey Flip), if you used a S/L as long as your hanging canopy, allowing the canopy to still hang freely so you could control the heading, I think it might give you some altitude gain with no disadvantages. I would like to try this one.

 

Tree,

This thread started by me telling a story about a unique jump I witnessed. That is all I wanted to do. I thought the BASE community would be interested to hear about it. Tom asked me to elaborate. So I gave him that courtesy. In my elaboration, I pointed out, that testing needed to be done (I had this idea months ago). I have said testing needs to be done throughout this whole thread.

My initial elaboration was challenged by Tom. I did not ask for this debate and I would like this debate to end, especially now that you have degenerated it.

The air molecule explanation is totally relevant to every BASE jump that ever happens, though it is a minor factor. Whether you think so or not. I initially tried to explain it in more layman terms, but Skin did not understand. So I elaborated further for him. Sorry if you did not understand it. It is just science, nothing personal.

This thread may have started with a story about an ultra low jump, but I have made no assertions about ultra low deployments. My assertions resulting from TomÕs debate were about anchor strength affecting inflation rate. I plan to do all my test jumps from the Perrine Bridge.

You can believe whatever theories you want, but you have made false accusations (re-read the thread).


Tom,
I am truly sorry if I came across as coming down on you. I was just trying to give you some constructive criticism. I also gave you some great compliments too. Tom, I do like you and enjoy jumping with you. I hope for you the feeling is mutual.

All right guys. Obviously Johnny and I have some disagreements about some relatively minor technical points that are really only going to be important on a small number of (fairly advanced) jumps.

That doesn't mean that we think each other are ignorant, stupid or inexperienced. It just means that our respective experiences have led us to different conclusions.

I'd be very interested in going out to the bridge with a video camera and some measuring devices and trying to figure out which of our approximations is closer to the far more complex reality. That way we can get some hard data that will be useful in keeping ourselves and others safe. All we're accomplishing here is burning up electrons (and perhaps amusing Tree ).


It is.

Comments such as "Sorry if you did not understand it. It is just science, nothing personal" are what got my knickers bunched up in the first place. Very condescending, as were many of the things you said to Tom. It doesn't help to have a bunch of knowledge if you piss people off trying to share it. No one is the single authoruty on any of this stuff, and trying to sell yourself as such never does justice. Relax, share, and enjoy. Gotta go jump now.

Cya

PS: I still love you Johnny.

And for the record I love both of you guys.

Johnny,

Thanks for the reply. I guess we'll have to agree to disagree over whether the events in gases at a molecular level are actually random or merely appear random through limited observation.

"If you understand physics, then why do you not understand this? "

C'mon man there's no need for that kind of condescension. My physics is just fine and the penomenon you're talking about (Brownian Motion) isn't really relevent. The microscopic effects of gas are not required in all cases to describe the macroscopic effect when the model has been reduced so extensively and over simplified. That was kind of the whole point of my post. Your assertion that air remains uncontrollable seems kinda odd given that you are a BASE jumper. What does a parachute do? House the magic levitation pixies?

There's a lot of ego in this game and a ton of bad things to happen. In fact, it can be a pretty miserable activity to be involved in. It would help if people kept their sense of humor and cooled their boots a little (and that comment is not directed at you, Johnny). This is entertainment afterall. It's just a game. It's no more important than that. We're not ambassadors for the human race. We're just a little nuts. Pretty trivial.

I'm sorry if the terseness of your response was initiated by the butt gag but I looked at the picture again and I definitely see the helicopter but it still looks like your ass.

I fully expect a response to that last rather offensive remark but hey, write something that puts a smile on everyones face, make me look like the asshole I am and enjoy the feeling as people sit at their computers, nodding their heads in agreement and murming "get him, Johnny".

We all need something to smile about.

Spread the love, Johnny.

Skin (Now and forever a Johnny Utah fan).

 

skin stop posting and start working on getting your arse here! there are things to do and women and skydivers to insult!

put away your league of gentlemen tapes and baby oil and get your arse to the homelands!!

Be safe scablicker...........

Love ya work!!!

M

I have a favor to ask. This is a potentially productive thread. If we let it degenerate into bickering and semantics, it will get locked.

Technical threads are relatively infrequent here, especially ones where there are several very experienced jumpers contributing opinions.

Lets try to keep them open and promote a friendly environment here where people can feel free to post questions without fear of being flamed.

After all, when all the dust is settled, we're all family here.

I echo that favor.

I would hesitate to call much of this post a "debate." I prefer to think of it as a roundtable of discussion on some interesting and thought-provoking issues.

Still listening...

Emphasis mine.

I believe that the opening of a parachute is governed by the "chaos theory", or "sensitive dependence on initial conditions". Meaning that no matter how carefully the parachute is packed, there is always an apparently random element involved. This "random" element may be triggered by something as small as the creases in the parachute fabric, or having the lines in just a couple millimeters in the wrong place; in short, I believe that bad openings may result from packjob variations so small that it is not practical to control them.

I don't think anyone is going to iron their parahute to improve openings.


I agree. I'm sure there are ways to improve to current methods, but it is my belief that it is impossible to completely remove the "random black death"-factor from a packjob, just as it is impossible to make an accurate weather forecast for a date one year from now.

What I said here was basicly posted already by others, but I didn't see anyone mentioning the chaos theory, which in my opinion plays a large part in parachute openings.