Turbulence question

[Whamie 0]

Hello fellow skydivers!

I am 130 lbs flying a Sabre 210.
This past weekend I noticed that I hit some turbulence while flying the Sabre. I've flown through turbulence before but this was the first time it felt like a really bumpy ride. Because of the bumpy ride, i made sure i wasn't making drastic turns or diving turns. My question is, in higher then usual turbulence and on a lighter WL, should i be concerned of a canopy collapse?

Sorry, for the noob question but wanted to get some answers from experienced flyers.

Thanks mucnh.

[Remster 24]

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My question is, in higher then usual turbulence and on a lighter WL, should i be concerned of a canopy collapse?

Yes.

There's a reason you;ll often find the experienced folks sitting one down when others keep going. And a high/low wingload is no cure for the issue.

Remster

[zerospinskier 1]

Anyone is susceptible to canopy collapse due to turbulence, but lighter wing loadings are more vulnerable since the have less pressure keeping the cells inflated. Going into partial brakes can help keep the canopy inflated more strongly.

Do you own this Sabre 210? or was it rental gear you were using? As a light person your canopy progression will have to be slightly slower than someone who is heavier since canopies will fly more aggressively even at lower wing loadings for you. But you should be able to get up to the 0.9-1 WL area safely. That would be a better (more common) place to hang out rather than the 0.7 you are at now if you want to be able to cut through turbulence a little better.
(Edit: Only relevant if you have maxed out the canopy control on this current wing loading and feel ready to downsize. You certainly don't have to. Your current setup will work great for many more jumps if you so chose.)

[Remster 24]

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Anyone is susceptible to canopy collapse due to turbulence, but lighter wing loadings are more vulnerable since the have less pressure keeping the cells inflated. Going into partial brakes can help keep the canopy inflated more strongly.

Do you own this Sabre 210? or was it rental gear you were using? As a light person your canopy progression will have to be slightly slower than someone who is heavier since canopies will fly more aggressively even at lower wing loadings for you. But you should be able to get up to the 0.9-1 WL area safely. That would be a better (more common) place to hang out rather than the 0.7 you are at now to help you cut through turbulence a little better.

Yes. Downsizing is exactly what you need to do to fight turbulence....


Fuck me.

Remster

[wmw999 2,120]

But the OP did the right thing when caught in unexpected turbulence by minimizing maneuvers. The more evenly your canopy flies, the better its chance of not collapsing.

Yes, any canopy can collapse, any time. But it rarely happens -- fly as thought it might, and keep jumping.

And generally a collapse isn't a complete collapse -- so a big canopy losing 3 cells' worth of canopy is going to be way better than a small one losing 3 cells' worth of canopy.

Wendy P.

There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

[Whamie 0]

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Anyone is susceptible to canopy collapse due to turbulence, but lighter wing loadings are more vulnerable since the have less pressure keeping the cells inflated. Going into partial brakes can help keep the canopy inflated more strongly.

Do you own this Sabre 210? or was it rental gear you were using? As a light person your canopy progression will have to be slightly slower than someone who is heavier since canopies will fly more aggressively even at lower wing loadings for you. But you should be able to get up to the 0.9-1 WL area safely. That would be a better (more common) place to hang out rather than the 0.7 you are at now to help you cut through turbulence a little better.

yes sir, it is a rental Sabre 210 w/ just 23 jumps on it.

[zerospinskier 1]

Quote

Quote

Anyone is susceptible to canopy collapse due to turbulence, but lighter wing loadings are more vulnerable since the have less pressure keeping the cells inflated. Going into partial brakes can help keep the canopy inflated more strongly.

Do you own this Sabre 210? or was it rental gear you were using? As a light person your canopy progression will have to be slightly slower than someone who is heavier since canopies will fly more aggressively even at lower wing loadings for you. But you should be able to get up to the 0.9-1 WL area safely. That would be a better (more common) place to hang out rather than the 0.7 you are at now to help you cut through turbulence a little better.

Yes. Downsizing is exactly what you need to do to fight turbulence....


Fuck me.

That's not what I meant. Obviously your answer of waiting it out when the weather is bad is the safest and best answer.

But now moving into the fluid dynamics of the canopy, yes lighter WLs will get knocked around in the wind more. You should keep this in mind and maybe sit out even more often with this lighter wing loading.

Then as an additional piece of info, a slightly higher (but still reasonable and safe) WL will be able to handle staying inflated with bumps in the air better than a lower WL. I'm not saying someone should. I am just saying that is how it works.

[wmw999 2,120]

Theoretically it should be true. However, one doesn't hear of that many students having canopy collapses, and they tend to have lower wing loadings.

I'm going to suggest that, if your experience level is accurate reflected by your profile, this might be a better time to listen than talk. I don't think I've ever said that before, but it's warranted here. I've several hundred jumps on a loading of under 1:1 and never had a collapse. Anecdotal, but so is most canopy collapse information.

Canopy collapse is one of those areas where it really can happen to nearly anyone given the right circumstances, it's not always one's own fault, and the best decision can end up with a bad consequence because of outlying factors. It's not something we can (or should) practice.

Wendy P.

There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

[zerospinskier 1]

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Theoretically it should be true. However, one doesn't hear of that many students having canopy collapses, and they tend to have lower wing loadings.

I'm going to suggest that, if your experience level is accurate reflected by your profile, this might be a better time to listen than talk. I don't think I've ever said that before, but it's warranted here. I've several hundred jumps on a loading of under 1:1 and never had a collapse. Anecdotal, but so is most canopy collapse information.

Canopy collapse is one of those areas where it really can happen to nearly anyone given the right circumstances, it's not always one's own fault, and the best decision can end up with a bad consequence because of outlying factors. It's not something we can (or should) practice.

Wendy P.

You're right. I guess I was more just talking about being bounced around rather than actual canopy collapse. I thought I could help, but I have no problem sitting out and keeping my mouth shut.

[Whamie 0]

Before getting on the load i looked out at the field and judging by the wind sock the winds were light (the wind sock was not even half way erect..it was loose and limp).
However, I think on the ride up to altitude, the winds might have picked up because when I landed, the wind sock was toward the half way erect position.

Because I plan to be on a 210 for awhile (at least until the end of the year because i can only make it out to the DZ 1x a month,,,until i can get my own rig) i just wanted to know if turbulence has certain effects on lighter WL like mine.
I'll take a canopy course on my next DZ visit.

[wmw999 2,120]

That sounds like an excellent plan and rationale.

By the way, one thing to think about when looking at the windsock isn't just whether it's limp or not, but how much the wind is fluctuating. Because if the wind is steady 5 with gusts to 15, that's very possibly worse than steady 18 gusting to 20. You might not want to jump in either condition, but 10mph gusts are worse than 2mph gusts, as a rule.

Wendy P.

There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

[IJskonijn 38]

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That sounds like an excellent plan and rationale.

By the way, one thing to think about when looking at the windsock isn't just whether it's limp or not, but how much the wind is fluctuating. Because if the wind is steady 5 with gusts to 15, that's very possibly worse than steady 18 gusting to 20. You might not want to jump in either condition, but 10mph gusts are worse than 2mph gusts, as a rule.

Wendy P.

On the point of trying to judge how much turbulence there is, the surroundings are important too. High trees cause a lot of turbulence, even if the wind is otherwise nice and clean. I had that problem a few weekends ago, where I had already drifted downwind of the DZ in strong winds (my own fault, and that on a canopy control course) and had to choose between landing on a good field left or a good field right. I picked right, and hit quite a bit of turbulence in the last 100ft. Only after landing did I realize the source, a bunch of high trees 50m upwind of my landing spot...

[billvon 2,393]

>Then as an additional piece of info, a slightly higher (but still reasonable and safe)
>WL will be able to handle staying inflated with bumps in the air better than a lower WL.

And a collapse that would be a minor inconvenience on a light WL might translate to a simple direction change that would be fatal on a heavily loaded canopy.

[NWFlyer 2]

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By the way, one thing to think about when looking at the windsock isn't just whether it's limp or not, but how much the wind is fluctuating. Because if the wind is steady 5 with gusts to 15, that's very possibly worse than steady 18 gusting to 20. You might not want to jump in either condition, but 10mph gusts are worse than 2mph gusts, as a rule.

Also, pay attention to who is jumping. If it's all people with less than 200 jumps and tandem/video, think long and hard about whether you really want to be in the air. Look at what the longtime locals (who aren't working) are doing. If they're sitting on the ground watching others get experience, maybe you should join them.

The last couple weekends at my home DZ have sucked, wind-wise. The winds have been coming from the north/northwest, and have been high, gusty, or both. At my DZ, that's about the worst direction for winds to be coming from, because they're coming over a stand of trees, or over DZ buildings and nearby hangars. Watching the wind sock on Saturday, it was not only going up and down, but also side to side, and despite the anemometer readings that sounded okay (11-14 mph) I stayed on the ground a while longer while watching the sock bump around like it was. Others went up, but I like to see a long stretch of reasonably consistent winds before I'll get in the air after the air has shown itself to be that unsettled.

I'm a wind wuss, but I'm totally okay with that.

"There is only one basic human right, the right to do as you damn well please. And with it comes the only basic human duty, the duty to take the consequences." -P.J. O'Rourke

[zerospinskier 1]

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>Then as an additional piece of info, a slightly higher (but still reasonable and safe)
>WL will be able to handle staying inflated with bumps in the air better than a lower WL.

And a collapse that would be a minor inconvenience on a light WL might translate to a simple direction change that would be fatal on a heavily loaded canopy.

You are right. I didn't mean to come across as if I was saying it was safer to be on a smaller canopy. My fault.

My DZ almost always has a turbulence filled wind shear layer around 2000ft. When I was jumping a 240, I would get bounced around through this layer a lot. As I made steps down I noticed less and less bouncing around. That is what made me say what I did. But I do understand it is much safer to stay on a bigger canopy and deal with a little bumps in the flight, than to progress too fast and injure yourself on landing. I apologize if it came out as unsafe and wrong information.

[popsjumper 2]

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Before getting on the load i looked out at the field and judging by the wind sock the winds were light (the wind sock was not even half way erect..it was loose and limp).
However, I think on the ride up to altitude, the winds might have picked up because when I landed, the wind sock was toward the half way erect position.

Because I plan to be on a 210 for awhile (at least until the end of the year because i can only make it out to the DZ 1x a month,,,until i can get my own rig) i just wanted to know if turbulence has certain effects on lighter WL like mine.
I'll take a canopy course on my next DZ visit.

Just to be clear...
It's great that you are checking winds prior to jumping (I'll assume you meant 'manifesting'). You wouldn't believe how many people get on jump planes not having any clue whatsoever as to what the winds are doing.

But just to be clear, wind socks, in and of themselves, do not indicate turbulence. Your description only indicates a change in wind speed, not turbulence.

A windsock CAN indicate turbulence where it is:
- quickly changing direction
- spinning
- going haywire, say in a thermal or dust devil
- indicating a direction and/or speed different than another indicator close by
- and others....

I hate turbulence and I hate the jumpers at my old DZ because tehy used me as a turbulence indicator.


I fly with my legs crossed but when I hit urbulence, them legs spread out like a gymnast doin' a split. It's uncontrollable.


"Oh hell...we got turbulence. Andy's legs flew out at 2K."

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

[chutem 0]

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Before getting on the load i looked out at the field and judging by the wind sock the winds were light (the wind sock was not even half way erect..it was loose and limp).
However, I think on the ride up to altitude, the winds might have picked up because when I landed, the wind sock was toward the half way erect position.

Because I plan to be on a 210 for awhile (at least until the end of the year because i can only make it out to the DZ 1x a month,,,until i can get my own rig) i just wanted to know if turbulence has certain effects on lighter WL like mine.
I'll take a canopy course on my next DZ visit.

Just to be clear...
It's great that you are checking winds prior to jumping (I'll assume you meant 'manifesting'). You wouldn't believe how many people get on jump planes not having any clue whatsoever as to what the winds are doing.

But just to be clear, wind socks, in and of themselves, do not indicate turbulence. Your description only indicates a change in wind speed, not turbulence.

A windsock CAN indicate turbulence where it is:
- quickly changing direction
- spinning
- going haywire, say in a thermal or dust devil
- indicating a direction and/or speed different than another indicator close by
- and others....

I hate turbulence and I hate the jumpers at my old DZ because tehy used me as a turbulence indicator.


I fly with my legs crossed but when I hit urbulence, them legs spread out like a gymnast doin' a split. It's uncontrollable.


"Oh hell...we got turbulence. Andy's legs flew out at 2K."

Every DZ needs one of those/you.

[toolbox 0]

Yes,you should worry about heavy turbulence.
Many young jumpers will often use the "If I had more wing loading,I could better cut through turbulence" rational for downsizing.
While it is true that heavier canopy loading will help cut through turbulence,it should not be the big determining factor in downsizing.
You should not downsize until you have mastered all the performance of your present canopy and can fly it well in slow flight, and full flight, and land softly with accuracy downwind,no wind,or in perfect wind conditions.
Remember that a more heavily loaded canopy can cut through turbulence better,but they can also collapse,and when a small heavily loaded canopy collapses it is a far worse scenario than a big lightly loaded canopy.
If the turbulence is causing end cell collapse or severe drop outs,directional control issues,ect...,then wait until the conditions calm down before getting back in the air.
Remember,it is better to be on the ground wishing you were in the air than it is to be in the air wishing you were on the ground.

[wolfriverjoe 1,340]

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... When I was jumping a 240, I would get bounced around through this layer a lot. As I made steps down I noticed less and less bouncing around...

You feel more bouncing around because the bugger canopy is going slower and has more area to create more lift. If you think about kites, a bigger kite will pull harder on the string when a gust hits it, right?

But bigger canopies are less affected by a partial collapse, and will reinflate with less altitude loss (because they descend slower).

So they are safer.

And the advice about watching who sits down when the winds pick up is a good one.
If the "old farts" sit down while the "young'uns" keep jumping, think about it.
When the "old farts" grab cameras and lawn chairs and go out to watch the "young'uns" landing...
Think about it very hard.
As in: "Why are you going out there with the camera?"
(Old fart responds)"We're gonna watch the young'uns gain some valuable experience about winds and turbulence"

"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

[JohnSherman 1]

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Anyone is susceptible to canopy collapse due to turbulence, but lighter wing loadings are more vulnerable since the have less pressure keeping the cells inflated. Going into partial brakes can help keep the canopy inflated more strongly.

This is a total mis-understanding about the internal cell pressure on a Ram-Air.
The internal cell pressure on a Ram-Air is ambient.
In that air is a non-compressible liquid it has ony 2 levels of pressure: Static & Dynamic. Ambient is Static corrected for enviromental variables. Dynamic however requires the additional component of Velocity. Dynamic Pressure "Q" = 1/2RHO V^2.
There is no circulation or air movemnet inside a cell, therefore no velocity.
Wing loading is not an issue in turbulance, but it is sure more scary. In turbulance the correct procedure is to apply brakes approximately equal to your deployment brakes. This does cause the pressure differential between the inside and the outside to increase. The point of greatest lift or of the greatest pressure differential is just before a pending stall. This high differential will cause the boundary layer to be stronger and resist detaching, which is what happens when that rotar blowes it off of the top of your canopy causing a relaxisation of the wing.
Your braked toggle position will not absolutly prevent this detachment but it does put you in the best position for an instant recovery. You should not loose significant altitude using this method.

[yoink 321]

John,

That brings to mind several questions -
firstly are all turbulence induced collapses a function of detached laminar flow over the wing? Can collapses be caused by external mechanical turbulence exerting a direct force on the surface (flying through rotors behind trees for example)

and if so, secondly what are the relative advantages to the prevention method you describe, vs maintaining a high internal pressure via full speed flight to increase the force necessary to induce a collapse.

From my flights on speedflying wings almost all of those resist collapses better at full drive, and also reinflate almost instantly after a collapse in that configuration - this may be a peculiarity to that wing design and may not be applicable to skydiving canopies.

[wolfriverjoe 1,340]

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In that air is a non-compressible liquid it has ony 2 levels of pressure

Huh?

Since when did air become a "non-compressible liquid"?

"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

[yoink 321]

I believe he's saying that in the environment of a canopy cell it is incompressible - being an open system as it is. Try pushing on a fluid in a pipe with two open ends... bet you can't compress it.

At least that was what I took from his post.

[labrys 0]

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Since when did air become a "non-compressible liquid"?

I was lernt in school that air is a compressible fluid

Owned by Remi #?

[wolfriverjoe 1,340]

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I believe he's saying that in the environment of a canopy cell it is incompressible - being an open system as it is. Try pushing on a fluid in a pipe with two open ends... bet you can't compress it.

At least that was what I took from his post.

You can compress it in a windsock.

Air blows in, but can't escape as fast as it would like to, so the sock inflates. The pressure rises in proportion to the wind velocity, so the higher the wind, the "firmer" the sock becomes.

"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