How to sink in a X-braced wing?

[alan 1]

Nice posts Brain, thanks for the valuable information. One thing has jumped out at me several times now in this thread.

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pulling high when necessary

I think this practice should at the very least be approached with considerable caution. I'm on a 4- way RW group out of an Otter. The group ahead of me is an 8-way and they take a little longer than normal to climb out and pick up their grips.

Upper winds are say 50 kts, so they notice this and take their time. My group moves in the door and watch the ground travel to ensure adequate exit seperation. By now the groups of freeflyers are getting concerned about their spot and are encouraging us to go. We eventually go when it is safe. The group after us is 3 way FF with no grip exit. Maybe they are by now quit convinced that they have gotten quite hosed on the spot. They don't realize that the spot is still good and the longer delays between exits were due to the higher upper winds. Big DZ, we don't alwys know each other. These guys are relatively inexperienced yet and may not fully appreciate the subtleties and importance of proper exit seperation.

These guys move to the door and go in just 2 or 3 secs. Now lets go back to my 4-way group, you're on it BTW! We had planned breakoff at 3500' and opening at 2500', at least that is what we told manifest and the load organizer. But, you see the bad spot and break off at 5000' and deploy around 4500'. Did I forget to mention we had video, so the camera guy dumps at 5000'.

Now we are those freefly dudes that were in such a hurry to follow us and what was their planned opening altitutde? Does anybody know those guys? Will they open high? Say didn't a tandem follow them out, were they expecting anyone to be open at 5000'? Just think of the poor person doing vid for that tandem, flying back to earth to get the opening as he falls away.

Just a few thoughts posed with the intention to motivate us to think about this.

Think more.
Learn more.
Live longer.

Hey, while I have you and am thinking of it, you were going to send me Ninja to evaluate last Spring. Did that just die slow death, or was it set to a back burner?

alan

[skygod7777 0]

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You are the first, second, or whatever group out. You notice a long spot. You dump at say, 5000'. The next group notices the spot as they get in the door and compensate by giving a quick 3 sec of separation instead of say 5 or 7. They were expecting you to open at say 2500', so they think that they are good opening at 3000' to help compensate.

well this situation should never occur in the first place, let me sat that first.

and second, you shouldn't be counting in the door for seperation, you should be looking for the "45 degree angle". so giving 3 seconds isn't near enough time, and anyone who would give less time due to the spot, in my opinion is dumb, that's putting yourself and the people infront of you in a lot more danger than what they need to be.

so, given you do have enough separation, then pulling high really won't matter, as long as you pull, and then start heading downwind (back towards the dz).

and you are right, pulling high on a dz that has a few airplanes running wouldn't be the best idea, that's why we all need to look down before we get out, to prevent having to pull high, or landing off.

but you did make a good point, but we don't need to re-think out old practices, we may just need to use them, like spotting. not many people i know from bigger dz's know how to spot.

later

[PhreeZone 15]

> you should be looking for the "45 degree angle".

Kelly don't make me come over there and smack you around for this one... You know the 45 degree thing is the biggest myth in jumping. You can never reach 45 degrees and you get to that "point" every time no matter the ground speed. Seach it out and the answers are there.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[skygod7777 0]

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Kelly don't make me come over there and smack you around for this one... You know the 45 degree thing is the biggest myth in jumping. You can never reach 45 degrees and you get to that "point" every time no matter the ground speed. Seach it out and the answers are there.

that's why it's in quotations. what i was trying to say is you need to look for separation, not count. i mean, sometime the uppers are strong enough that 5 to 7 seconds isn't long enough for separtation, that's why you need to look down, and while you looking down, you may want to take a look at the spot to see if your long
later

[grega 0]

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sometime the uppers are strong enough that 5 to 7 seconds isn't long enough for separtation

Huh this is totally out of the threads question, but why would strong winds change the separation time. it's strong winds for whole load. So horizontal distance from 1st group to the plane in 5 sec is exactly the same in no wind or in strong wind. It's the airspeed that's important for separation not the ground speed. And the airspeed depends on the airplane not the wind.

Or am i missing something?

"George just lucky i guess!"

[alan 1]

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well this situation should never occur in the first place, let me sat that first

I agree, but with todays bigger planes nd bigger DZs and less emphasis on spotting, or even looking before going, I just don't trust those people after me in the plane. I don't know them or their abilities. It just should not happen, but we know it does.

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and second, you shouldn't be counting in the door for seperation,

Very true. In different post of mine in this same thread where I am addressing this issue again, I point out that one should be checking the separation distance by observing now far the airplane has travelled across the ground. I know Mike Mullins often says wait "x" number of seconds, but that is usually based on an observation of ground speed. People don't know that so it gets to be a rule of thumb, not realizing it changes as the conditions warrant.

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you should be looking for the "45 degree angle".

Apparently I'm leary of those behind me for good reason. That 45 degree advice is as bad or worse than opening high. Several people have done models on exit separation and demonstrated the weakness with the 45 degree angle. Try John Kallend's web-site, he does a very good analysis and does a nice presentation at SDC safety day. John is a regular poster here, maybe he will jump in. I think his profile may have a link to his site.

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so giving 3 seconds isn't near enough time,

Depends on the ground speed of the A/C and the winds.

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and anyone who would give less time due to the spot, in my opinion is dumb, that's putting yourself and the people infront of you in a lot more danger than what they need to be.

That is kinda my point, but I also am not too impressed by anyone that thinks it is OK to open high on a bad spot from an Otter, especially if they are using tht 45 degree thing on a day with high upper winds nd mixed groups of jumpers.

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so, given you do have enough separation, then pulling high really won't matter, as long as you pull, and then start heading downwind (back towards the dz).

The problem is, as you can see, you can't count on having enough separation. Pulling high and then flying back down the windline is a bad idea. First fly at 90 degrees to the windline then turn and fly parallel to it back to the DZ. Think about another Otter on the same jump run, 2 or 3 minutes back. The first group on the first plane all open at 5 or 6K then fly back along the jumprun. The first group on the second plane opens at 2500'. Hmmm.....

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but you did make a good point, but we don't need to re-think out old practices,

No, some of them need more thought. Another example is flying in half brakes in turbulence. The newer canopies used today are just not designed for that. 45 degrees for exit separation, nope. Open and fly back to the DZ on the wind line, not with bigger planes and several of them using the same jump run.

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we may just need to use them, like spotting.

Yes, we all need to improve or spotting knowledge and skills. It is a continully ongoing process.

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not many people i know from bigger dz's know how to spot.

Ummmm...... ya, but it is not always their fault. They need good information to begin with. Things change, we need to be aware and adapt.

alan

[PhreeZone 15]

The issue is that having a strong upper wind slows the plane's ground speed. This reduced ground speed lowers the amount of seperation between groups. To get the correct ammount of seperation it might take a longer delay in higher winds.

Think of a helicopter in a hover, even with a 10 or 20 delay there still is going to be no horizantal seperation.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[BrianSGermain 1]

There are two keys to ample separation.

One is time in the door between groups. This comes as a result of intellect winning over emotion. Panic results in bad decisions.

The second component is "canopy tracking". Separation can be significantly enhanced by flying the canopy perpendicular to the jumprun immediately after opening.

Given both of these measures, issue of opening altitude becomes a moot point. The act of pulling high (4-5000') does not effect the outcome of the scenario. The salient factor is Location, not Altitude. If you are not directly above a canopy, you cannot fall into it.

Think More,
Discuss More,

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[alan 1]

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There are two keys to ample separation.

One is time in the door between groups. This comes as a result of intellect winning over emotion. Panic results in bad decisions.

I agree Brian and I think my posts bear that out, although time in the door is really a function of groundspeed. When looked at that way it boils down to the same thing.

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The second component is "canopy tracking". Separation can be significantly enhanced by flying the canopy perpendicular to the jumprun immediately after opening.

Yes, I said essentially the same thing in a response to Kelly (skygod7777). This one is often forgotten, especially on a long spot. The natural tendency is to head straight back.

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Given both of these measures, issue of opening altitude becomes a moot point.

Yes, in perfect world. My worry about telling people to open high if the spot is bad is that we can't rely on the mentioned measures and won't be able to until we are all perfect.

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The act of pulling high (4-5000') does not effect the outcome of the scenario.

Probably, it is a big sky, even if emotion won out over intellect in the group behind you. If you tell load you re going to open at 5k to experiment with a new canopy, they usually insist you go to the front of the plane with the tandems and students. If we could rely on adequate separation and canopy tracking, that really shouldn't be the case.

I just can't help but feeling that opening high on bad spot means you are putting too much trust in the people behind you and thereby increasing the risk to yourself. I guess other factors come into play. We should also weigh the comparative risks of an off landing to the possibility of a collision. At many DZs landing off is no big deal, just a longer walk back. At some DZs, it could mean landing in water, trees, structures, etc.. At some boogies, they used to warn the new people not to open high unless they were out last and informed the pilot.

Well, this has really sidetracked a good portion of this thread. Maybe they should move it or give it it's own thread.

alan

[BrianSGermain 1]

I have begun a thread on this topic. We should take this conversation there so the original discusion can remain "germane". I always wanted to use that word in a sentence...

+

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[crazy 0]

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I'm on a 4- way RW group out of an Otter. [...] Upper winds are say 50 kts, so they notice this and take their time. My group moves in the door and watch the ground travel to ensure adequate exit seperation. By now the groups of freeflyers are getting concerned about their spot and are encouraging us to go. [...] These guys move to the door and go in just 2 or 3 secs. [...]Will they open high? Say didn't a tandem follow them out, were they expecting anyone to be open at 5000'?

Where is the problem? At opening time, first they will be lower (they are falling much faster) and then they will have plenty of horizontal separation (they will have much less wind drift, something like 20seconds X 50kts = 500 meters).
Looks like you spent a lot of time and effort to build a scenario where you think it's a problem to open higher than the next group. Can you spend even more time and more efforts to build a scenario that might convince others?

Ok, let's say the next group were belly flyers as well... So, what's the point? they left way too early and didn't give enough horizontal separation. I agree, this is dangerous idiocy. Do you really think that opening lower than the next group generally increases the safety, just in case they would be the 2 seconds separation maniacs?

Let me push the reasoning a bit further. if you open 1 foot, 10ft, 100ft, 1000ft or 10000ft higher than them, it doesn't make much difference if they are going to fall through your open canopy. So, lower has to be lower (30ft lower, for the length of the lines and a bit of margin :-).
Since they are idiots, they might even forget to pull, which makes them good cypres candidates. So, to be really safe, plan ahead, switch the cypres off, and pull lower than cypres altitude, right? Here, i was optimistic, i assumed someone checked that their cypres is on.

Well, there is obviously a flaw in this logic. Apparently, pulling lower than the suspected opening altitude of the next group, just in case they were idiots, doesn't sound like a great idea. So, can we please accept the fact that opening higher than the next group is not a safety violation when it comes to freefallers falling into opened canopies?

--
Come
Skydive Asia

[alan 1]

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So, can we please accept the fact that opening higher than the next group is not a safety violation when it comes to freefallers falling into opened canopies?

Why do DZs have rules about exit order then? Typically large face to earth RW groups go first, then smaller RW groups in descending order, then large freeflyer groups in descending order, then students, then tandems. Wing suiters get added in if any and skysurfers, if any, I think they put by the door.

People like Bryan Burke at Skydive Arizona have spent a lot of time and effort to build a scenario where they think it's a problem to open higher than the next group. Couldn't he spend even more time and more efforts to build a scenario that might convince others? I think people at USPA have even spent time and trouble on this on, enough to have included it in the SIM.

alan

[meatbomb 0]

I believe (note the use of the word believe, not know) that the exit order at Eloy, and for that matter, at my DZ (since we use the same rules) is primarily based on ensuring horizontal separation. The reason students, and high pullers go last, is that you can get back further from a higher altitude, so with 10 groups out of an Otter (for an eg) the last few high pullers will still have a good spot.

My point is...vertical separation is not an issue, as horizontal separation is maintained, and even the last groups out don't get hosed, as they're opened higher...perfick!

---
Swoopert, CS-Aiiiiiii!
Piccies

[alan 1]

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I believe (note the use of the word believe, not know) that the exit order at Eloy, and for that matter, at my DZ (since we use the same rules) is primarily based on ensuring horizontal separation.

That is exactly my point. And if someone opens high, then you loose the horizontal separation. Also, I have been trying to get people to understand is that you can't rely on getting the separation you want on a long spot for other reasons. There are people who won't wait long enough and others that will even track back along the line of flight.

I understand very well the reasons for Tandems, students and other intentional high pullers for going last.

Try this just for kicks. Manifest a four way for an Otter load, that should put you in the second to fourth group out, but be sure to tell manifest and the loader that you all intend to pull at 5 or 6K. Shouldn't matter right? After all, with proper exit separation it doesn't matter if you open high.

alan

[crazy 0]

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[exit order is primarily based on ensuring horizontal separation]
That is exactly my point. And if someone opens high, then you loose the horizontal separation.

Well, maybe we should clarify which horizontal we are talking about. I was talking about the horizontal at right angle with the vertical. Are you talking about an other one? Or are you assuming that the general direction of freefall is not vertical?

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Also, I have been trying to get people to understand is that you can't rely on getting the separation you want on a long spot for other reasons. There are people who won't wait long enough and others that will even track back along the line of flight.

So, what is your suggestion about opening altitude? Is it to open lower than the next group? I wish all S&TA would have your progressive views about safety :-)

--
Come
Skydive Asia

[velo90 0]

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Why do DZs have rules about exit order then? Typically large face to earth RW groups go first, then smaller RW groups in descending order, then large freeflyer groups in descending order, then students, then tandems. Wing suiters get added in if any and skysurfers, if any, I think they put by the door.

1. The largest RW group goes 1st because they generally need the most time for the climb out. This means they can be climbing out before they reach the start of the spot.

2. Freefly after RW is because of freefall drift.

3. Students and Tandems next not because of vertical seperation, it is because they pull high and have a better chance of getting back to the DZ on a long spot.

4. Wing suiters last because they can take a really long spot

5. Dunno about skysurfers. They have gone 1st at my dropzone, but that's because it's the only way they can gear up and exit.

[alan 1]

The questional was rhetorical and in response to the quibbling by crazy about accepting the fact that freefallers won't fall into your canopy, but thanks anyway.

alan

[alan 1]

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Well, maybe we should clarify which horizontal we are talking about. I was talking about the horizontal at right angle with the vertical. Are you talking about an other one? Or are you assuming that the general direction of freefall is not vertical?

The same. If you open high, you don't continue to drift horizontally while in vertical freefall and the canopy can open facing pretty much any direction, including back along the line of flight.

The person/group that exited after you is still drifting horizontally during their freefall. They can catch up to you if they did not leave enough separation on exit. But then, you knew that, didn't you and you know that I know it. You just wanted to quibble.

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So, what is your suggestion about opening altitude?

Open at your planned altitude unless there is an emergency that requires opening higher or lower. A bad spot is not always an emergency, but there are exceptions to that and circumstances should be taken into consideration such as DZ location, number of jumpers, exit order, and number of aircraft.

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I wish all S&TA would have your progressive views about safety :-)

I don't know about a progressive attitude, most S&TAs are familiar with USPA freefall training that instructs a student to open at their assigned altitude unless there is an emergency. I can't recall the portion of the SIM that says to open high in the event of a bad spot, maybe you could post it here for all of us. I can recall the sections that deal with off landings, landing hazards, and obstacles.

alan

[crazy 0]

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The person/group that exited after you is still drifting horizontally during their freefall. They can catch up to you if they did not leave enough separation on exit. But then, you knew that, didn't you and you know that I know it. You just wanted to quibble.

I'm not quibbling. I fail to get your logic.
The effect of the winds is the same (in drift distance/time unit) on a freefaller and on an open canopy. In addition, the risk of collision disappears as soon as the freefaller is lower than the open canopy. So, i don't really understand how the claim that "the person/group that exited after you is still drifting horizontally during their freefall" is relevant (the open canopy is drifting as well, and it doesn't really matter how much the freefalling group drifts while they are lower than the open canopy). If you could clarify with an example (with numerical values), i would appreciate.

Then, the assumption that "they can catch up to you if they did not leave enough separation on exit" is true whatever the opening altitude. Hence, if it is a concern at 5000ft, please explain why it is not a concern anymore at 3000ft.

--
Come
Skydive Asia

[alan 1]

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The effect of the winds is the same (in drift distance/time unit) on a freefaller and on an open canopy

As long as the freefaller is not tracking the effect is not the same. Once the canopy is open it begins to fly. If there is a 40 mph wind, the freefaller is still moving downwind at 40 mph. The canopy can fly against the wind at something around 30 mph. Think of a sailboat sailing against the current and a piece of driftwood floating with it. Maybe not a perfect analogy but perhaps you can follow it.

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Then, the assumption that "they can catch up to you if they did not leave enough separation on exit" is true whatever the opening altitude. Hence, if it is a concern at 5000ft, please explain why it is not a concern anymore at 3000ft.

I think if the canopy is not flying into the wind then it increases the distance from the group after you, no. Think of the same sailboat and the same piece of driftwood only now the saliboat is going with the current of the the body of water.

alan