Am I wrong? What should I do or have done?

[kallend 1,623]

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thanks for the ridiculous word problem.

WHOOSH

It's not an exercise in math (the math is extremely simple). It's an exercise in UNDERSTANDING.

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The only sure way to survive a canopy collision is not to have one.

[strop45 0]

OK, I'll bite. 11 seconds separation and plane is travelling at 50ft/sec relative to balloon. First group is overhead of the balloon, second group is 11*50=550 feet away.

Both groups track 300', therefore there is a 50' overlap, i.e. insufficient separation. If one of the second group has a high speed mal, they are likely to fall near some of the group one jumpers.

The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

[hallux 0]

understanding what? sounded like a reading comprehension drill. YOu made this way more difficult than necessary and quite frankly.... silly. You need to understand K.I.S.S.

and yes the math is relatively simple and also completely uneccessary. Along with most everything else.

The real answer is still that morons exited a plane over a balloon that they mistook as a 2500ft water tower that suddenly popped up next to the DZ.

understanding is good, the best way to do that is to get to the point. So whats the groundspeed in KNOTS and was 11 secs a correct seperation? excuse me...was 990ft correct? and what was the age of the girl and on a scale of 1-10 how loose was she? and if her speed is relative to the wind then how does that affect her cock blowing speed? I'm guessing for this convoluted scenario that it was 10 in/sec. Keep in mind that one knot is equal to about 1.5 inches of cock per second.

[timmyfitz 0]

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I do not think that there was much for winds at altitude so the separation should have been 5 or so seconds. I have been spotting with groundspeed 40 miles an hour and when you look out the people are still below the plane and not drifting off as normal. so I had to do a 15 second count..

not much winds at altitude?
groundspeed of 40?

which was it? can't be both

I read it as two separate situations.

"I do not think that there was much for winds at altitude so the separation should have been 5 or so seconds."


"I have been spotting with groundspeed 40 miles an hour and when you look out the people are still below the plane"

Just not worded well.

[kallend 1,623]

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understanding what? ]

If folks really understood the effects of winds then situations like the OP described wouldn't happen.

I doubt this applies to you, though, with your obvious thorough knowledge of the kinematics of freefall.

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The only sure way to survive a canopy collision is not to have one.

[pinkfairy 0]

MANY dropzones have a right hand pattern if the wind blows one way, and a left hand if the wind blows another, this is to keep the pattern off the runways or over safe areas. I don't know if this was the case at the DZ you went to, but it's quite common. This should be made clear in the DZ brief.

Do NOT track up the jumprun, which is often along the runway. The direction of the jumprun should be made clear in the DZ brief.

Know what the exit separation is.

4k is a high pull in most countries and on most DZs.

And one very important tip that can save your life some day and make your canopy flying a LOT less stressful: Why were you in that pattern with all those people going in opposite directions at all? Wouldn't you rather see it all from above, and watching the first person down fly the pattern and go "Oh, wow, I think I missed something in the brief, silly me, this is a RIGHT hand pattern! well, I guess I'll fly a right hand pattern, then." This is how to make that happen: If you're open at 3, and you have a big, floaty beginner canopy, you should be able to float on half brakes until you're sure about what happens below you and if there's space in the pattern for you. Try it at home: Open like normal, while looking out for traffic, collapse your slider if you do that at all, then grab your toggles and pull them to the sweet spot (where you begin to feel that the brakes take effect), and you'll notice that you hardly sink through. You can easily turn while flying like this by letting one toggle slightly up, this is called a flat turn, and can come in handy in other situations too. Other people will start entering the pattern long before you, and when it looks like there's room for you, just fly into the pattern like normal. Talk to your favourite instructor about this, I can tell you, but I can't show you. With my Pilot 111, I can be first down or last, no problem, and with your canopy and opening altitude, I think waiting out on half brakes would be a very good strategy.

It sounds like you didn't get everything in the DZ brief, or that the DZ brief wasn't good, and as a result you had a jump with a couple of unsafe situations. I think your normal opening altitude is a bit high, and you should inform other jumpers in the plane about this so they know about it and can avoid you. When you get more experienced and better at flying your canopy, you'll be less likely to suddenly find yourself going against traffic. When you've heard some DZ briefs, you'll know what the basics usually are, and it will be easier to understand even a bad one, and you'll be more likely to ask the relevant questions to get the information you need. That way you'll be safer at any DZ.

Stuff like this happens in skydiving, and I wouldn't worry so much about who was right or wrong, more about what you can do to make yourself and people around you safer. You and your own gear are the only factors in skydiving that you have any control over.

I hope this was any help, and that you learn from this experience.

Take care and Blue Skies!

Relax, you can die if you mess up, but it will probably not be by bullet.

I'm a BIG, TOUGH BIGWAY FORMATION SKYDIVER! What are you?

[mnealtx 0]

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The real answer is still that morons exited a plane over a balloon that they mistook as a 2500ft water tower that suddenly popped up next to the DZ.

I guess they didn't have the 'mad eye skillz' that you do.

Mike
I love you, Shannon and Jim.
POPS 9708 , SCR 14706

[bluetwo 0]

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(Groups size within discipline groups doesn't matter a bit so big to small, small to big doesn't matter a whit. For that matter example, I'd rather go 10w, 2w, 8w rather than 10w, 8w, 2w for better safety/separation of the big groups.)

Lots of good info in this thread! Concepts this newbie never thought of before and such. One thing I can't understand is what is meant by 10w, 8w, 2w etc.

I searched that but didn't find anything. Can anybody clear that up or should I expect flameage for not knowing it?

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[wolfriverjoe 1,340]

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(Groups size within discipline groups doesn't matter a bit so big to small, small to big doesn't matter a whit. For that matter example, I'd rather go 10w, 2w, 8w rather than 10w, 8w, 2w for better safety/separation of the big groups.)

Lots of good info in this thread! Concepts this newbie never thought of before and such. One thing I can't understand is what is meant by 10w, 8w, 2w etc.

I searched that but didn't find anything. Can anybody clear that up or should I expect flameage for not knowing it?

No flames from me. If you don't know, ask. The only stupid question is the one you don't ask (well, other than "Why can't I jump a wingsuit, camera or really small canopy at 25 jumps)
10w is shorthand for "10way", a group of ten jumpers going in a group.

I understand rehmwa's logic in keeping the larger groups seperated by a smaller group, but I don't agree with it. The larger groups fall slower due to interference drag (Prof Kallend explains it nicely in the "Vladiball" thread that was recently resurected).
And I was taught that fall rate is the key. It determines how long you are exposed to the wind, and therefore how far you will drift.

"There are NO situations which do not call for a French Maid outfit." Lucky McSwervy

"~ya don't GET old by being weak & stupid!" - Airtwardo

[bluetwo 0]

Cool....

So what if you wanted to separate those groups like this? 2w, 8w and 10w. Wouldn't that put in the fastest order? If I understand you right and the bigger groups would be falling slower.

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[skyjumpenfool 2]

Two comments...

Half breaks? You might even try rear risers. It tends to be more efficient, but, a bit harder on the arms.

Secondly, I think the only way you were wrong was in not talking about this with the folks there and then making a couple more jumps. You never learn by giving up. And, there was definitely something here to learn.

Birdshit & Fools Productions

"Son, only two things fall from the sky."

[wolfriverjoe 1,340]

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Cool....

So what if you wanted to separate those groups like this? 2w, 8w and 10w. Wouldn't that put in the fastest order? If I understand you right and the bigger groups would be falling slower.

I was taught that groups should go out slowest to fastest (not including high pullers like AFF and tandem or wingsuits).

The reasoning for this is that (for a standard upwind jumprun with the winds not shifting direction significantly with altitude) the groups will be blown backwards up jumprun. The slower fallers will be exposed to that wind for a longer period of time and pushed further because of it.
So the slower fallers go furthest back. That means they should be first so that the seperation is the greatest. If a slow group went out after a fast group (think headdown) it is possible to have the slower group blown over top of the faster group.

Group separation is a subject of considerable debate, Search Results for that term will give you some thoughts.

Prof Kallend has a nifty program on his home website (linked from his profile) that shows how fallrate affects separation.

"There are NO situations which do not call for a French Maid outfit." Lucky McSwervy

"~ya don't GET old by being weak & stupid!" - Airtwardo

[danornan 64]

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Two comments...

Half breaks? You might even try rear risers. It tends to be more efficient, but, a bit harder on the arms.

Secondly, I think the only way you were wrong was in not talking about this with the folks there and then making a couple more jumps. You never learn by giving up. And, there was definitely something here to learn.

Lots of good info here...

John, sometimes you make my hair hurt!

and..... You can learn by stopping what you feel (in your mind) is a dangerous situation. You don't get hurt by NOT jumping. It would have been a good time though to ask a few more questions of those in charge...

Dano

[strop45 0]

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I understand rehmwa's logic in keeping the larger groups seperated by a smaller group, but I don't agree with it. The larger groups fall slower due to interference drag (Prof Kallend explains it nicely in the "Vladiball" thread that was recently resurected).

If you assume that you need 300 feet separation between jumpers in a group, then the 10 way group needs to track for 485 feet, the 8 way group needs to track for 390 feet while the 2 way group only need 150 feet.

I guess the question is: "is extra throw generated by the 10 way group being slower than the 2 way group sufficient to make up for the extra 240 feet of additional tracking distance"?

The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

[kallend 1,623]

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I understand rehmwa's logic in keeping the larger groups seperated by a smaller group, but I don't agree with it. The larger groups fall slower due to interference drag (Prof Kallend explains it nicely in the "Vladiball" thread that was recently resurected).

If you assume that you need 300 feet separation between jumpers in a group, then the 10 way group needs to track for 485 feet, the 8 way group needs to track for 390 feet while the 2 way group only need 150 feet.

I guess the question is: "is extra throw generated by the 10 way group being slower than the 2 way group sufficient to make up for the extra 240 feet of additional tracking distance"?

I don't think you can make that generalization. Any effect of group size on drag will be overwhelmed by whether or not they are fat bastards, if they are wearing fast or slow suits, and whether or not they are wearing weights.

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The only sure way to survive a canopy collision is not to have one.

[rehmwa 2]

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Exit order should be determined, among other things, by pull height. Lowest pullers out first, and stacking canopy openings to the highest ones out last, which is usually the tandems.

John - SERIOUSLY?

I've highlighted the part that you apparently missed in your first read.

So, if you have two four-way belly-fly groups, one opening at 4k, and one opening at 2.5k, which goes first?

I saw it - I didn't want some newbie to think that "amongst other things" minimized those things,,,,, like fall rate. opening altitude is pretty far down the list of things to prioritze exit order that you can just about take it off the list (unless it's a sure thing and trustable - like tandems)

And yeah, I agree with that scenario. But I'd also consider who had the faster descending canopies as well as the group to try to put closest to directly over the top (1st or 2nd depending on the winds that day) = let's disregards swoopers that spiral down to 2K, then float in half brakes (thus squashing up the queue) to get their swoop perfect.

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Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[rehmwa 2]

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I don't think you can make that generalization. Any effect of group size on drag will be overwhelmed by whether or not they are fat bastards, if they are wearing fast or slow suits, and whether or not they are wearing weights.

Thank you, that's why we can 'assume' that groups within a similar freefall discipline all fall "approximately" at the same fall rate - 117 vs 125 is a lot different than 120 average vs 160 average.

at least for separation

and that's why sandwiching that two way between the two bigger groups is pretty much safer in general in reducing traffic

AND, to go with the whole 'big ways fall slower thing' - I'd still put that smokin' 2 way out on the green light and let that slow 100 way provide separation just with the long drawn out climb out...... . If I had a plane with 102 person lift capacity.... (this is mockery, the 102 way would have tremendously long tracks, and no one would let that 2 way on the same jump run....)

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Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[billvon 2,400]

>So, if you have two four-way belly-fly groups, one opening at 4k, and one
>opening at 2.5k, which goes first?

Doesn't matter too much. Video is going to pull at breakoff, so you'll have a deployment at 4K and 6.5K as well. Either way a lack of horizontal separation is going to get you.

If one group has video and the other doesn't, it generally makes sense to put the group with video out first no matter what altitude they are pulling at. (Larger-group first rule.) If neither has it, then it doesn't matter too much. Putting the 2.5K jumpers out first may give a little extra horizontal separation; putting the 4K jumpers out first may help ensure that they land on the DZ. If they are pulling at that altitude because they're new that may be important.

[rehmwa 2]

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putting the 4K jumpers out first may help ensure that they land on the DZ.

or last, depends on the jump run - whether the exit is before or after going over the top.....

I would prioritize the 2.5K over the 4K group to put the 2.5k group closer to the airport - to maximize them all landing on the DZ.

Then, you might have the 2.5k 4way team thinks they should go first and they might sit at the green light and hose the others every time - you might move them to the back of the plane.....

etc
etc
etc

ad nauseum

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Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[pinkfairy 0]

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Two comments...

Half breaks? You might even try rear risers. It tends to be more efficient, but, a bit harder on the arms.

He's a beginner. Grabbing toggles and fly at the sweet spot is easier than grabbing toggles and then rear risers, which is going to be both heavy physically and more complicated. Using only toggles will achieve what he needs: keep the vertical separation to the people with smaller canopies who pulled lower than him. I can land last using only toggles with my 1.3:1 wingloaded canopy, if he's got an appropriately sized canopy for his experienve level, so should he.

Relax, you can die if you mess up, but it will probably not be by bullet.

I'm a BIG, TOUGH BIGWAY FORMATION SKYDIVER! What are you?

[rehmwa 2]

some canopies float more efficiently with risers, some with brakes (or "breaks" as people call them here.....)

depends

it is simpler to let newbies only have one tool, but eventually they need to at least try to learn to use the risers and the harness for canopy control - hopefully they taught the newbie about rear risers and avoidance in Cat D - that's pretty early

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Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[pinkfairy 0]

He doesn't need to "max" his canopies floating capabilities in order to land last if he pulls high and has a wingload suitable for beginners.

But I see your point.

Relax, you can die if you mess up, but it will probably not be by bullet.

I'm a BIG, TOUGH BIGWAY FORMATION SKYDIVER! What are you?

[billvon 2,400]

>or last, depends on the jump run - whether the exit is before or after
>going over the top.....

Right. Most jump runs start out downwind of the airport and run quite far upwind, depending on winds etc. On a "maximum" jump run (i.e. one that's trying to get as many people out on one pass as possible) the first group is barely going to make it back, flying into the wind, and the last group will barely make it back flying _with_ the wind.

>I would prioritize the 2.5K over the 4K group to put the 2.5k group
>closer to the airport . . .

Agreed - which on a maximum-time jump run means out second.

And this discussion has already gotten well beyond what most people do at the DZ.

"We're a five way"
"We're a four way, you go first."
"But you have camera too, so it's really five, so you go first." (subtext - the five way guy isn't sure he can spot)
"OK."

[skyjumpenfool 2]

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[
He's a beginner. Grabbing toggles and fly at the sweet spot is easier than grabbing toggles and then rear risers, which is going to be both heavy physically and more complicated. .................

Agreed! But my sugestion was to introduce his thought process to include all controls available. There's a huge difference in wing deflection between brakes and risers, play with and learn both. Do it high at first to see how it goes.

Birdshit & Fools Productions

"Son, only two things fall from the sky."

[rehmwa 2]

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so it's really five, so you go first." (subtext - the five way guy isn't sure he can spot)

exit order is very 'complicated'

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Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants