0
davelepka

Offsetting ADD opening Altitudes WAS: Fatality - Cross Keys - 3/25/11

Recommended Posts

Quote

Quote

A better way would be, as opted in this discussion, to change the parameters of the unit. Correct me if I'm wrong but the parameters of current AAD's (and opening altitude) come from say 15 years ago when canopies opened much faster and there weren't HP-canopies. Maybe these parameters should be revised to the current era of skydiving.


There is nothing wrong with the unit. Reserve canopies still have the very same requirements.

The problem is in the user. If you have an ADD you should know its operating parameters and you not suppose to exceed those.

AFAIK CYPRES was designed to prevent no pull.
It is not angel. It has just a set of algorithm for saving your life if needed. You should not the limitation if its use. If you know that those are not applicable than make sure you switch it off. E.g.: I would turn it OFF in case of a hot-air balloon jump.

You can have a second chance to live. If you get a 2-out because of your low pull that's your own stupid fault.



I totally agree that the main problem is that skydivers today rely too much on backup devices (AAD, RSL, Skyhook etc.). They alter there hard-deck because of these backup-device which in my opinion is wrong. I will never rely on my Cypres and have never pulled below 2.500 ft because that's my hard-deck.

If you're conscious and your Cypres fired then you fucked up a couple of times along the road and it's your own fault and you should deal with the consequences.

The problems occur when you're unconscious and can't predict if you're in a stable enough position for your reserve to open in time when your Cypres fires. AFAIK this is why we have a Cypres, at least this is why I have a Cypres.

One question, why would you turn your Cypres off in case of a hot-air balloon jump? Never heard of that one. I did one 5 years ago and am doing one next month so I'm interested in this particular case. It's always good to learn new things.
Blue skies!

Share this post


Link to post
Share on other sites
Quote

One question, why would you turn your Cypres off in case of a hot-air balloon jump? Never heard of that one. I did one 5 years ago and am doing one next month so I'm interested in this particular case. It's always good to learn new things.


In case of balloon jump do you know where you are going to land? Do you know the elevation of the landing area relative to the place of take off?

If no than it should be OFF.

Share this post


Link to post
Share on other sites
Quote

Quote

One question, why would you turn your Cypres off in case of a hot-air balloon jump? Never heard of that one. I did one 5 years ago and am doing one next month so I'm interested in this particular case. It's always good to learn new things.


In case of balloon jump do you know where you are going to land? Do you know the elevation of the landing area relative to the place of take off?

If no than it should be OFF.


Gotta take that in account when jumping in other countries. Here in the Netherlands it's pretty easy because when haven't got any mountains and the elevation will not be more than 50 ft :D.
Blue skies!

Share this post


Link to post
Share on other sites
>and I cannot find any info in the Cypres user manual about activation
>elevation adjustment at different fallrates.

There's no adjustment involved. When you are falling on your back, the pressure on your back (where the AAD pressure sensor is) is 200-300 feet "lower" than the pressure on the other side of you. This makes the AAD fire 200-300 feet higher, because it thinks it's lower than it is.

Share this post


Link to post
Share on other sites
Quote

>and I cannot find any info in the Cypres user manual about activation
>elevation adjustment at different fallrates.

There's no adjustment involved. When you are falling on your back, the pressure on your back (where the AAD pressure sensor is) is 200-300 feet "lower" than the pressure on the other side of you. This makes the AAD fire 200-300 feet higher, because it thinks it's lower than it is.



Bill, please explain that a bit more.
Life expands or contracts in proportion to one's courage. ~Anais Nin

Share this post


Link to post
Share on other sites
Most AAD's are set to go off at a given air pressure which is figured from the ground air pressure and the air pressure at their activation altitude. They account for the fact that on your belly your ADD is sitting in a burble and the pressure there will be slightly different than if it was outside that burble. When you eliminate the burble (On the back, side, tumbling) the AAD is still going to activate when it reaches the same air pressure levels, its just you are reaching that level 200-300 feet further off the ground.

This is why if you toss your main at say 1100 feet and you are sniveling for a few seconds you might have a AAD fire at 900 feet even though you have not reached the 750 foot mark where it was expected to fire. It saw the elimination of the burble when you were stood up and suddenly was in the activation air pressure parameters and the unit activated.
Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

Share this post


Link to post
Share on other sites
Quote

The CYPRES speed is designed for swoopers, I believe the Vigil has a Swoop mode, not sure about the Argus (not that it matters in most rigs)



The Argus does have a swoop mode. Unlike the CYPRES, it keeps the activation speed the same, but detects when your canopy opens, and will not fire after that, regardless of speed.

From the manual:

Quote

1.3.4 «SWOOP» Mode
The Argus releases at 820 Ft. (250 meters) and below if a speed is reached equal or higher than 78 mph (35 m/sec). The Argus stops monitoring and goes to stand-by after it detects an opened parachute. Please be aware that this mode is not suitable for wingsuit-flyers!


"It's amazing what you can learn while you're not talking." - Skydivesg

Share this post


Link to post
Share on other sites
Quote

>and I cannot find any info in the Cypres user manual about activation
>elevation adjustment at different fallrates.

There's no adjustment involved. When you are falling on your back, the pressure on your back (where the AAD pressure sensor is) is 200-300 feet "lower" than the pressure on the other side of you. This makes the AAD fire 200-300 feet higher, because it thinks it's lower than it is.




That's an interesting statement.

and I mean that in as neutral a way as possible

Share this post


Link to post
Share on other sites
Quote

Quote

>and I cannot find any info in the Cypres user manual about activation
>elevation adjustment at different fallrates.

There's no adjustment involved. When you are falling on your back, the pressure on your back (where the AAD pressure sensor is) is 200-300 feet "lower" than the pressure on the other side of you. This makes the AAD fire 200-300 feet higher, because it thinks it's lower than it is.




That's an interesting statement.

and I mean that in as neutral a way as possible



I am still not clear about your question.

To say the following, I looked at visual aid posted on dropzone.com some time ago.

Novice/Student unit/modes typically have lower speeds required for activation.

Expert/Tandem units/modes use a uniform 78 mph.

The CYPRES2 Speed version uses 96 mph, and won't fire below 330 feet.

The Argus Speed mode still uses 78mph, but disarms when it thinks it saw a parachute open.

None fire at different altitudes depending on how fast you are falling.

The exact altitude at which any AAD will fire will depend on body position. None of the AADs can figure out if you are belly down, or belly up, so your attitude will change the firing altitude because of the different pressures the sensor will see depending on your body position.

Does this cover it?

Share this post


Link to post
Share on other sites
Quote

None fire at different altitudes depending on how fast you are falling.



The student CYPRES does.

Quote

None of the AADs can figure out if you are belly down, or belly up, so your attitude will change the firing altitude because of the different pressures the sensor will see depending on your body position.



The Argus supposedly has sensors to determine orientation, but I have never seen much information about it. I know neither what sort of sensors it uses, nor how it uses the extra information.
"It's amazing what you can learn while you're not talking." - Skydivesg

Share this post


Link to post
Share on other sites
Thanks for the clarification Eric. That makes sense to me.
One more question though, is the 200-300ft difference a rough estimate based on test jumps/past cumulative real world AAD fires? Or is that fairly accurate based upon testing done to differentiate the pressure variations between a burbled sensor vs a non-burbled sensor?


Quote

Most AAD's are set to go off at a given air pressure which is figured from the ground air pressure and the air pressure at their activation altitude. They account for the fact that on your belly your ADD is sitting in a burble and the pressure there will be slightly different than if it was outside that burble. When you eliminate the burble (On the back, side, tumbling) the AAD is still going to activate when it reaches the same air pressure levels, its just you are reaching that level 200-300 feet further off the ground.

This is why if you toss your main at say 1100 feet and you are sniveling for a few seconds you might have a AAD fire at 900 feet even though you have not reached the 750 foot mark where it was expected to fire. It saw the elimination of the burble when you were stood up and suddenly was in the activation air pressure parameters and the unit activated.


Life expands or contracts in proportion to one's courage. ~Anais Nin

Share this post


Link to post
Share on other sites
Quote

Quote

None fire at different altitudes depending on how fast you are falling.



The student CYPRES does.



Oops, you are correct. My apology. Always good to have someone rechecking my work. Thanks!

But still, for the purpose of this discussion, I don't think it is what he was asking about, really.

I was thinking more along the lines of "The faster you are going, the higher the AAD should fire".

The STUDENT CYPRES behavior is just the opposite of that. If you are going faster, it fires lower. It only fires higher if you are going slower.

But, still, my mistake, and I thank you for pointing it out.

Quote



Quote

None of the AADs can figure out if you are belly down, or belly up, so your attitude will change the firing altitude because of the different pressures the sensor will see depending on your body position.



The Argus supposedly has sensors to determine orientation, but I have never seen much information about it. I know neither what sort of sensors it uses, nor how it uses the extra information.



I have heard of that hardware too.

What the Argus supposedly has, but apparently does not use, is of little consequence.

When I hear from Aviacom that they actually use that to determine orientation, it will be different.

If they actually had and used that hardware, I'd expect it to be a sales point -"Fires at X altitude REGARDLESS OF YOUR BODY ORIENTATION".

(But, all things considered, how likely do you think it is that we will hear that?)

Share this post


Link to post
Share on other sites
>One more question though, is the 200-300ft difference a rough estimate based
>on test jumps/past cumulative real world AAD fires? Or is that fairly accurate
>based upon testing done to differentiate the pressure variations between a
>burbled sensor vs a non-burbled sensor?

Both. Airtec did a LOT of testing on the system, and there are some systems (like the Astra) that moved the sensor to the front for this very reason.

Share this post


Link to post
Share on other sites
Quote

There's no adjustment involved. When you are falling on your back, the pressure on your back (where the AAD pressure sensor is) is 200-300 feet "lower" than the pressure on the other side of you. This makes the AAD fire 200-300 feet higher, because it thinks it's lower than it is.



Could this also mean that AADs might not detect your decelleration for some time? That is, your deploying main is slowing you down, but as your body is being stood up, pressure might be rising near your back faster than just that due to change in altitude. If so, it seems like it might have the effect of momentarily thinking you are falling at a faster rate than you really are.

Share this post


Link to post
Share on other sites
Quote

>One more question though, is the 200-300ft difference a rough estimate based
>on test jumps/past cumulative real world AAD fires? Or is that fairly accurate
>based upon testing done to differentiate the pressure variations between a
>burbled sensor vs a non-burbled sensor?

Both. Airtec did a LOT of testing on the system, and there are some systems (like the Astra) that moved the sensor to the front for this very reason.



Never even having seen an Astra, I don't have docs to check or anything.

If they moved the sensor to the front, that means it will fire lower if you are back-to-earth?

Share this post


Link to post
Share on other sites
>If so, it seems like it might have the effect of momentarily thinking you are
>falling at a faster rate than you really are.

Yes. Or more accurately, they do not sense you decelerating as fast as you really are, so you are still over that 80mph threshold when you reach an altitude that the AAD _thinks_ is 750 feet.

Share this post


Link to post
Share on other sites
Quote

Let's be honest... Far too many jumpers are astonishingly ignorant of their gear.



You know, I really get tired of hearing people beat a dead horse on nearly EVERY safety related issue in our sport. Glideangle however, has absolutely nailed it.
Chuck Akers
D-10855
Houston, TX

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

0