Let's talk about exit seperation

[billvon 2,400]

>Yep, but throw not affected by any wind, it's only matter of airspeed
> and specific of your body and the way as you present it to the relative air flow

Agreed. Which is an argument to plan for belly-first even in light winds.

[NWPoul 1]

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I think I'm starting to understand what you're saying, but I still don't agree with all of your points. As far as throw from the plane, we're generally in agreement. However, as unpredictable as the difference in throw from an RW group and a freefly group can be, it's likely that putting the slower fallers out first maximizes separation more often than not. Whether it's equivalent to a 3 second difference or a half second difference, I don't know. But putting freeflyers out first will put the groups closer together by the same amount, whatever it may be, except in less likely cases where the RW group gets more throw.

Let's assume that this "3 sec throw" is a fact
so as far as it's undependend from wind - it's constant so you can simple add this 3 second to exit delay between RW and FF without affecting their spotting = same horisontal separation plus more time and vertical separation:)

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Now as far as time between groups... you're saying that separation at deployment isn't affected by wind speed, as long as the wind speed is steady, right? You're taking into account that after the first group opens, they will continue to drift with the wind away from the second group, so separation at the second group's deployment time is independent of wind speed. Personally, I wouldn't rely on wind drift under canopy for horizontal separation. Canopies are flying in all directions right after opening. If we all jumped non-steerable rounds, it'd be a different story and I might agree with you.

First it is good when canopies don't fly all deretion after opening but fly perpendicular to the jump run (more easily for relatively low members in FF group than big RW btw:) )
But lets canopy flying all diretion - this will be the same for any order and any wind and all flying canopies still continue flying in moving air mass so there is no wind for them:)

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But now lets talk about order. You seem to advocate putting fast fallers out first to minimize canopy traffic. I'd like to see your graphics of the freefall trajectories and how exit order affects separation in freefall and at opening. Kallend's model clearly shows how, on an upwind jumprun, for any given exit separation and wind speed, putting out the fast fallers after the slow fallers maximizes separation. In fact, fast fallers out first tends to cause the slow falling group to cross paths with the fast falling group, risking a collision if the lower group has a premature deployment. Does your model look different?

No! I am advocating to put FF first when there NO wind shift and therefore drift and overlay of slowfallers onto fasfallers!
If there is significant wind shift and therefore drift - than we use the RW first order

Why drink and drive, if you can smoke and fly?

[NWPoul 1]

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>Yep, but throw not affected by any wind, it's only matter of airspeed
> and specific of your body and the way as you present it to the relative air flow

Agreed. Which is an argument to plan for belly-first even in light winds.

Or jusr add this 3 second to exit delay between FF and RW as far it;s constant (does not affected by the wind) and proveding the same H separation and spotting add 3 second of time and some altitude separation to you favor:)

Why drink and drive, if you can smoke and fly?

[pilotdave 0]

See the three attached images from kallend's program and help me understand your point.

Parameters are constant wind of 20 kts from exit to opening (no shift). 5 second delay. The white line represents the first group to exit, yellow is the second group.

2 groups falling at the same speed.
Slower group then faster group.
Faster group then slower group.

What am I not understanding about this? Would your graphs look different?

Dave

[rehmwa 2]

I see NWPohl's points - and it seems to be a thread of talking past each other.


1 - Our current slow before fast assumes - winds at altitude and winds below are in similar directions and uppers are faster than lowers. It's a good assumption. I think NWP acknowledges this, but also notes that it's good to understand the bookkeeping when the assumption isn't true. I think that's all he's talking about, nothing more. Posters acting like this is advocating changing up exit order, I believe, are imagining an agenda I have yet to see him write.

other than that:

2 - Kallend notes throw vs freefall discipline is much more significant than most people think. He's right.

3 - There are very few scenarios, where RW before FF isn't always a good assumption.

4 - People like to argue semantics and piss about little details and find it fun and frustrating.

5 - Billvon's rules of thumb are pretty good for most wind conditions.

6 - never assume vertical separation helps in safety is even remotely as important as horizontal separation - there are very few people remaining that dispute this now (at least on these forums) - it 'could' help, but it's not predictable and can't be relied on.

I like cake.

...
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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http://www.omniskore.com/freefall_drift2.html

cool, I didn't know this still was out there

...
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

[pilotdave 0]

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I see NWPohl's points - and it seems to be a thread of talking past each other.

I think you're probably right, but:

"I am advocating to put FF first when there NO wind shift and therefore drift and overlay of slowfallers onto fasfallers! "

Maybe I'm misunderstanding what he means by wind shift. If he means zero wind, then I understand his point and still disagree with it. If he means no wind change, then kallend's model clearly shows otherwise.

Dave

[rehmwa 2]

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No! I am advocating to put FF first when there NO wind shift and therefore drift and overlay of slowfallers onto fasfallers!

I stand corrected - you are advocating changing up the exit order.

I think in this scenario - that switching it up to capitalize on a tiny bit of vertical separation (assumed) - is pretty minor and just confuses jumpers that don't understand the wind drift mechanics.

Heck - anyone in the group pull 3-4 seconds too soon, or too late will screw up your vertical sep. And, frankly, people in both groups with tiny canopies and people in both groups with big canopies will still be in each other's pattern just due to piloting styles.

You'd be better off arguing scenarios that show drift to require fast to go first - is there one? perhaps downwind jumpruns where the lowers are blowing opposite the uppers? cross wind jump runs are another good one to just figure out who is flying the tiny specks and let them out first - but that is not freefall discipline dependent by any means. (I get so mad in these threads when some newbie states that freeflyers are also the hot swoopers - idiots)

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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]

just caught that - thanks dave

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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]

>Or jusr add this 3 second to exit delay between FF and RW as far it;s
>constant (does not affected by the wind) and proveding the same H
>separation and spotting add 3 second of time and some altitude
>separation to you favor:)

Right. Or in winds add 12-30 seconds. Unfortunately it is next to impossible to get skydivers to wait 30 seconds between groups, and at most DZ's no one knows how to calculate what the separation should be in the first place.

On the other hand, if you put belly out first, there will be a very large gap created automatically between the belly and freefly groups - even if you wait under a second between groups. Add another 3 seconds there and you get all the separation you could ever wan.

[popsjumper 2]

Separation for an AN-2:
Wait until the guy before you opens and flies well off jump run, then wait another 15 seconds.








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My reality and yours are quite different.
I think we're all Bozos on this bus.
Falcon5232, SCS8170, SCSA353, POPS9398, DS239

[ecnuob 0]

Pardon my ignorance here but why not just run jump line perpendicular to the winds?

[billvon 2,400]

>Pardon my ignorance here but why not just run jump line perpendicular to
>the winds?

You can! You still have to put belly out first (throw still decreases your separation) but flying jump run perpindicular to the winds can help reduce the effects of wind. (Not eliminate them - you still have to leave more time between groups in high winds - but it can reduce the additional time you need.)

However, experience has shown that spotting is considerably tougher in those cases. That's not insurmountable, but you do have to plan ahead and have the spotters to pull it off.

[NWPoul 1]

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Pilotdave
"I am advocating to put FF first when there NO wind shift and therefore drift and overlay of slowfallers onto fasfallers! "

Maybe I'm misunderstanding what he means by wind shift. If he means zero wind, then I understand his point and still disagree with it. If he means no wind change, then kallend's model clearly shows otherwise.

No by wind shift I mean a difference between upper and lower wind.
Lets came to agreement at basic things first) My first point: The constant wind (no wind shift) = zero wind from separation point os view. So if you "understand his point" for zero wind you take it (yet you can disagree with it) at any constant wind.

Now regarding uploaded pics from Kallend's program:
1 Without differense between upper and lower wind the drift between the groups determine only by initial throw
2 I am surprized of amount of initial throw for FF, According to graph it takes 16-18 sec for FF to arrest the Horisontal speed from the plane, while for RW it's about 10 sec. Did you ever notice such defferense and time? From my limited expiriense in FF we start to work fully horizontally (i.e. Take grips, go around each other) after about 7 seconds from exits (I know that does not mean, that we completely stop H. Speed but at least at this moment we exposure even much surface to Horisontal component of Relative Wind than RW so should start to arrest rest of H. Speed not less than RW)
3 Mr. Kallend himself told us that he estimate that drift between RW and FF (caused by initial throw) is equal ~3 sec of exit delay, but in the graph the RW exited after 5 sec overtake FF for a good another 5 sec =/ If it true – than it's ultimate argument to put RW first, but I newer ever saw that RW exited 5 second later overtake the FF if they both dont tracking throgh the sky

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Rehmwa
6 - never assume vertical separation helps in safety is even remotely as important as horizontal separation - there are very few people remaining that dispute this now (at least on these forums) - it 'could' help, but it's not predictable and can't be relied on.

I think in this scenario - that switching it up to capitalize on a tiny bit of vertical separation (assumed) - is pretty minor and just confuses jumpers that don't understand the wind drift mechanics.

Heck - anyone in the group pull 3-4 seconds too soon, or too late will screw up your vertical sep. And, frankly, people in both groups with tiny canopies and people in both groups with big canopies will still be in each other's pattern just due to piloting styles.

Yes the horisontal separation the ultimate for safety in regard to deployment collision
When I wish more Vertical I refer mostly for the landind crowding
One or two early or later deployment does not impact the landing order, but when all RW and FF part of load are mixed – it's not very nice)


Once again this conserns came not from theory but from practice, when we read the DZ and was inspired by modern true order and start to implement it at any wind conditions and start to fight with "Oldschool guys" and try ti convinice the DZO that Fast Fallers should go after Slofallers while "common sence" and prev expirience say opposite... We have succed and new order was implemented almost at every load, than we started noticed, than it's can lead to discomfort at landig pattern... than we noticed, that when there no significant wind shif the "drift" of RW vs FF is also not so significant and quite minor relative to the main factors; exit delay and anintentional tracking. So at now if there is no strong upper wind we put the FF first (but if there big RW group, say 10+ jumpers they go first any way) and give the delay between last FF and first RW and usually we don't see the overlap shown in graphs... Also when staying on the ground and whatch the jumprun, exits and falling there are also not such drift observed

Why drink and drive, if you can smoke and fly?

[NWPoul 1]

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>Or jusr add this 3 second to exit delay between FF and RW as far it;s
>constant (does not affected by the wind) and proveding the same H
>separation and spotting add 3 second of time and some altitude
>separation to you favor:)

Right. Or in winds add 12-30 seconds. Unfortunately it is next to impossible to get skydivers to wait 30 seconds between groups, and at most DZ's no one knows how to calculate what the separation should be in the first place.

On the other hand, if you put belly out first, there will be a very large gap created automatically between the belly and freefly groups - even if you wait under a second between groups. Add another 3 seconds there and you get all the separation you could ever wan.

If there is 3 sec drift (according to Mr Kallend) than you can easily give just 3 sec coz it's doesn't affect the spotting and actually not so much
Regarding 12 sec for wind - if you show the groung which virtually doesn't move under the plane it should be quite easy to let any corresponding delay as soon as everyone aunderstand the positive of delay and saw that delay does not fly them far avay from the spot)...
But again do you bealive than strong upper wind (low ground speed) lead to less separation between the groгps at deployment (i.e. air distance) or you just CAN wait longer on exit providing the more separation yet still be on a good spot?

Why drink and drive, if you can smoke and fly?

[jclalor 12]

This is a very timely topic for me as I had another jumper snivel pass me yesterday, he was about 50 feet away while I had been under canopy for 2 to 3 seconds. We were both solo free flying and he exited right after me. He was learning to sit fly and I was thinking he might have back slid back towards me. I always sitfly away from jump run so If I backslide, I will not travel up or down the line of flight.

Is there a general rule about this with beginning solo freeflyers? I don't think I have ever heard this discussed.

[Rugby82 0]

In the Netherlands we teach all beginner Freeflyers to keep a heading that is 90 degrees off the line of flight.

This rule is true for both students and experienced Freeflyers. Just let the base keep heading 90 degrees off the line of flight and the rest will follow. This also helps with seperation during break-off between different groups because, with not so large groups, people will go in tracking off the line of flight.

Blue skies!

[winsor 186]

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I think we need to re-visit how that works. Anyone care to lead off?

This is a start.

It's over a decade old, but the physics haven't changed much in the interim.


Blue skies,

Winsor

[winsor 186]

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So, if you were to exit an aircraft with a 90kt airspeed and 0kt windspeed, you would be 'thrown' as much as if you exited with a 90kt airspeed and a 50kt windspeed?

Over the ground, no. In relation to the plane you just jumped out of, yes, the throw will be the same.

Isn't ground seperation the overall goal?

Nope.

You can have people landing in the same spot all day long without any of them occupying the same column of air ever.

OTOH, you can have all sorts of different landing points where someone cutting away would hit the lower person's canopy, or an inadvertant deployment would put the lower jumper into the upper.

The whole idea is to keep groups apart in the air, but to bring them to the same spot on the earth (the DZ, the pea pit or whatever).


Blue skies,

Winsor

[billvon 2,400]

>If there is 3 sec drift (according to Mr Kallend) than you can easily give
>just 3 sec coz it's doesn't affect the spotting and actually not so much . .

Right. So if belly flyers get out first you gain 3 seconds of separation automatically even in no wind. If freeflyers get out first you lose that 3 seconds of separation automatically. One can cause a collision if you forget about the extra 3 seconds; one will not.

>f you show the groung which virtually doesn't move under the plane it
>should be quite easy to let any corresponding delay as soon as everyone
>aunderstand the positive of delay and saw that delay does not fly them
>far avay from the spot)

No, that's not sufficient if you do the exit order backwards. You could let freeflyers get out, watch the ground move, wait what you think is sufficient time, get out yourself - and then watch those freeflyers drift right back under you.

However, if everyone falls at about the same speed, AND the winds are the same direction all the way down, then the method you mention can work.

>But again do you bealive than strong upper wind (low ground speed) lead
>to less separation between the groгps at deployment (i.e. air
>distance)

Strong upper winds and lighter lower winds (same direction) do indeed lead to less separation at opening time.

>or you just CAN wait longer on exit providing the more separation yet still
>be on a good spot?

In 99% of the cases you might consider, leaving enough time will give you adequate separation. However, often that will not result in a good spot for everyone on the load (which is why you sometimes have to take a second pass.) Adding the extra time required for separation if you choose freeflyers first will result in more people having bad spots (or more goarounds.)

[rehmwa 2]

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In the Netherlands we teach all beginner Freeflyers to keep a heading that is 90 degrees off the line of flight.

yeah - beginning freeflyers have such great awareness of line of flight - and/or heading control

it's a good concept - but pointless in practice IMO

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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

[DSE 3]

I feel this is a good tool to have as a reference.
Matt Veno did the calculations, and it's pretty simple to comprehend. For wingsuits, it's quite valuable.

[timmyfitz 0]

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In the Netherlands we teach all beginner Freeflyers to keep a heading that is 90 degrees off the line of flight.

yeah - beginning freeflyers have such great awareness of line of flight - and/or heading control

it's a good concept - but pointless in practice IMO

I guess if is pointless, they should quit teaching it. Most first jump students don't do things exactly the way they were taught so it's pointless to teach them.

[rehmwa 2]

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I guess if is pointless, they should quit teaching it. Most first jump students don't do things exactly the way they were taught so it's pointless to teach them.

see how easy it is? you just simplified your work load

go ahead and teach the theory and they'll learn about about freefall dynamics between groups.

I'd rather emphasize appropriate exit separation between groups than a method (tracking perp to line of flight and anything related to that) that's only good for two ways and smaller if the jumpers are heads up enough to actually do it.

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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

[timmyfitz 0]

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I guess if is pointless, they should quit teaching it. Most first jump students don't do things exactly the way they were taught so it's pointless to teach them.

see how easy it is? you just simplified your work load

go ahead and teach the theory and they'll learn about about freefall dynamics between groups.

I'd rather emphasize appropriate exit separation between groups than a method (tracking perp to line of flight and anything related to that) that's only good for two ways and smaller if the jumpers are heads up enough to actually do it.

Whoosh.