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cheneyneel

Re: [cheneyneel] Cypres Investigations???

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I mean that the hard core swoopers are normally without AAD's but there is a vast majority of us who are hard core up jumpers who fly canopies at comp levels but always have a AAD on religiously.... we need to know what compromising relationships that we are putting ourselves in and it needs to come form the AAD manuf no matter hwo they are... Ok there has been a guy with a fanny pack tying to set off a AAD but has there been any other controled constant R&D with HP landings recently that AAD manuf have published that I have missed bec I would like to read what they say???

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> we need to know what compromising relationships that we are putting ourselves in . . .

So far I know of one 'real' cypres fire, one cypres fire during a test, and two vigil fires. Right now we're pushing these devices faster than the manufacturers ever intended they go under canopy - so if you're loading a canopy at 2.5:1 and doing 720's, consider yourself a test pilot.

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A recent happening on a DZ in Norway(translated from a preliminary report):A highly experienced jumper recently had a Cypres AAD(not known if 1 or 2)deploeyd reserve canopy in low altitude(100ft AGL). The jumper was then in a high velocity final after more than 720 degree turn. It was a small crossbraced, less than 100 sqft. The jumper was wearing additional weights. During landing the reservecanopy deployed, and the jumper landed under two canopies without injuries.



This is from the Cypres` users manual:

"Even with extreme maneuvers during exit and in freefall, CYPRES will cope with it.
Whatever you can think of under canopy like stalls, spiral turns, down planes, hookturns
with the smallest canopies as well as any CRW, CYPRES will analyze these movements
without problems. It won't interfere with any normal activities while skydiving."

This might need some editing, after several incidents with HP canopies? Especially the part:"...Whatever you can think of under canopy..."

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This might need some editing, after several incidents with HP canopies? Especially the part:"...Whatever you can think of under canopy..."



Yup. I agree. The sport has changed since that manual was written, and since the Cypres was designed. I think each manufacturer needs to establish "tested" limits so users know what level of performance is appropriate. Bill said essentially the same thing as follows:
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Right now we're pushing these devices faster than the manufacturers ever intended they go under canopy - so if you're loading a canopy at 2.5:1 and doing 720's, consider yourself a test pilot.



In the airplane world manufacturers are required to establish a "demonstrated crosswind component" for each aircraft. That's the maximum crosswind that was tested through the certification process. It doesn't mean that a given aircraft can't handle a greater crosswind, just that the manufacturer hasn't officially experimented with a greater crosswind through the certification process. For example, my 1978 Cessna 172 has a "maximum demonstrated crosswind velocity for takeoff or landing" of 15 knots. It is specifically defined as "not considered to be limiting" so I can land with more crosswind if I want to, but it becomes a handful.

AAD manufacturers should begin to define specific maneuvers and wing loadings that they have tested. It helps to know what the firing parameters are (for example 78 mph), but users should also know how that speed relates to specific parachutes and maneuvers. Thus, I'd like an AAD manufacturer to say they tested the AAD with a Crossfire 119 at all possible deploed speeds, and that the unit is not recommended for smaller parachutes of similar design. Another option is for canopy manufacturers to test AAD's and offer minimum recommendations for users. In that case, Icarus might say to purchasers of Crossfires smaller than 109 that a Cypres is not recommended, and that an FXC 12000 is not recommended for any parachute.

There are obviously lots of variables with all the parachutes on the market, and now, all the different AAD's, so it's not possible to test every combination, but there should be some kind of tested standard to define an appropriate approved operating window.
.
Tom Buchanan
Instructor Emeritus
Comm Pilot MSEL,G
Author: JUMP! Skydiving Made Fun and Easy

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Another possibility would be to connect a lanyard or sensor between the AAD and the main canopy to inhibit firing if the main is still connected to the jumper. The added benefit would be the AAD wouldn't put your reserve into a canopy wrap situation,



and also nothing would happen during a no-pull... the time when an AAD is of most use... in fact, that's the very situation that 99% of jumpers bought a cypres to guard against.

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Another possibility would be to connect a lanyard or sensor between the AAD and the main canopy to inhibit firing if the main is still connected to the jumper. The added benefit would be the AAD wouldn't put your reserve into a canopy wrap situation,



and also nothing would happen during a no-pull... the time when an AAD is of most use... in fact, that's the very situation that 99% of jumpers bought a cypres to guard against.



...or a high speed malfunction. The problem with a Cypres firing when swooping is limited to a very small percentage of jumpers and canopies. The rest of us will benefit from a Cypres (or other AAD). I fly a Sabre 120 and have no reason to believe that I am at any risk of an AAD deployment regardless of what "normal" parachute operations I might be involved in. Sure, I could collapse the canopy by wrapping both break lines and blast through 750 feet causing the Cypres to fire, but that isn't a normal parachute flight. I should be able to, and can, do as many spins as I like at any altitude with my Sabre 120 without worry.

AAD's work. They save lives. Let's not get all bent about a unique problem that occurs with a tiny percentage of specific users and parachutes. Let's identify the area of concern and let's maintain advocacy of AAD for everybody that doesn't fly in that tiny piece of the sky.
.
Tom Buchanan
Instructor Emeritus
Comm Pilot MSEL,G
Author: JUMP! Skydiving Made Fun and Easy

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I should have clarified that a little: after sensing opening shock/deceleration, the firing would be inhibited unless the main has been cut away, prior to the point where the unit detects a normal under-canopy rate of descent nothing would change from the present design. Very poor explanation on my part. Sorry.
Yeah, you wouldn't want an AAD that only worked after a cutaway. Kinda pointless. :S

Let's wait and see what Airtec says (assuming the CYPRES actually did fire due to rate computation, we don't know that yet).

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>after sensing opening shock/deceleration, the firing would be
>inhibited unless the main has been cut away . . .

. . . so if you collided with someone's open canopy while still in freefall and were knocked out, then the cypres would be disabled? Seems like events like that are one of the main reasons the cypres was developed.

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. . . so if you collided with someone's open canopy while still in freefall and were knocked out, then the cypres would be disabled?



I think you could implement code that would rule out a scenario like that. For instance, it would not consider the jumper to be "under a good canopy" unless their rate of descent was < 35 fps for 5 seconds, or something along that line. I don't see it as an insurmountable problem, maybe I'm naive. ;)

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Let's identify the area of concern and let's maintain advocacy of AAD for everybody that doesn't fly in that tiny piece of the sky.
.


Or, let's make sure that most skydivers get as much information as possible concerning AADs and make them able to make an informed choice about whether to use one or not.
That's my preference. Ofcourse YMMV.
---
Unanswered questions are far less dangerous than unquestioned answers

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. . . so if you collided with someone's open canopy while still in freefall and were knocked out, then the cypres would be disabled?



I think you could implement code that would rule out a scenario like that. For instance, it would not consider the jumper to be "under a good canopy" unless their rate of descent was < 35 fps for 5 seconds, or something along that line. I don't see it as an insurmountable problem, maybe I'm naive. ;)



I think the logic to get even most situations is very difficult. And the end product would be unpredictable, esp when so many of us don't know the current operating parameters.

Best middle ground may be a simplistic unit that does deactivate after sensing a main opening. It would only be appropriate for those who have a ligitimate concern with deployment during swooping. For the rest of us it would be a step back as it would not cover potential emergencies where the AAD has been of value.

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It would only be appropriate for those who have a ligitimate concern with deployment during swooping.



Or it could change modes if it senses the main cutaway sensor is connected to the unit, otherwise it reverts to normal operation mode.
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I think the logic to get even most situations is very difficult.



I don't. I think defining the logic was originally very difficult, but I believe Airtec is totally capable of making modifications now that they have years of feedback and data analysis to study.

***And the end product would be unpredictable..."

How so? It's very predictable now, if code was added and debugged correctly, it shouldn't change the "predictability" of the firing sequence. We'll have to see how Airtec responds, assuming this was a case of the CYPRES actually initiating the reserve sequence and the unit was not damaged/interfered with externally.

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Or it could change modes if it senses the main cutaway sensor is connected to the unit, otherwise it reverts to normal operation mode.



adding a 'main cutaway sensor' increases your failure points, and attaching anything to the main which violently opens every jump is asking for trouble. Far more trouble than just not using the Cypres if you're doing very high performance canopy work.

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It's very predictable now, if code was added and debugged correctly, it shouldn't change the "predictability" of the firing sequence.



You know how the debugging is ultimately done, right? In the air. Airtec can test for situations it expects, but skydivers have a way of finding new ways. The current logic is very simple, though they do something to deal with tumbling. But to handle this exception case, suggestion include dearming the unit after detection of a main opening, but still need to know to rearm for a problem. Sounds very messy. Any swooper would want to know clearly what mode the unit is in - if necessary they can always do a 90 instead of a 720 and keep the speeds down.

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. . . so if you collided with someone's open canopy while still in freefall and were knocked out, then the cypres would be disabled?



I think you could implement code that would rule out a scenario like that. For instance, it would not consider the jumper to be "under a good canopy" unless their rate of descent was < 35 fps for 5 seconds, or something along that line. I don't see it as an insurmountable problem, maybe I'm naive. ;)



Mabey you can get one of the other manufactures to implement that, since there AADs are mode selectable... The "SWOOP" mode could do exactly what you state, and Expert mode could remain the way it is now for the rest of us that are not going to push those limits. I know that for my type of flying, I would prefer that they do not start changing the way the thing works, I dont need it changed.. Some of you do. Multi-Mode and selectable (like I think the other AADs already are) is the best option.

FGF #???
I miss the sky...
There are 10 types of people in the world... those who understand binary and those who don't.

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> It's very predictable now, if code was added and debugged correctly,
> it shouldn't change the "predictability" of the firing sequence.

Every time you add a mode or a decision point, you (at minimum) double the complexity of testing a device. Keep in mind that the cypres is not processing data from dozens of sensors; it is using exactly one sensor which is sensing one parameter. Trying to extrapolate a great deal of information from that one parameter (like end of freefall or resumption of freefall) is just not that simple.

Keep in mind that even though its job now is very simple, it sometimes fires if you open a bit low and sometimes doesn't fire if you cut away at 600 feet. Adding more modes where it may not fire seems like it could cause more problems than it solves.

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Bill,

I agree about the testing being more complex, but this part:

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Trying to extrapolate a great deal of information from that one parameter (like end of freefall or resumption of freefall) is just not that simple.



Airtec creates quite a thorough investigation from returned units presently, including orientation, altitude and rate of fall prior to activation, so I still believe the data to implement my idea is already available within the unit.
Oh, and a "cutaway sensor" could be something as simple as a 2-wire connector with a shorting link that is tied to an RSL ring, for example. Very simple, no moving parts.

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Adding more modes where it may not fire seems like it could cause more problems than it solves.



Airtec needs to determine that, and my opinion is we'll never see it.

I'm not going to post anything else on this thread, I've had my say. It was all just "food for thought" anyway. Thanks for all the thoughtful replies and opinions, folks.

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A couple people in the "incident" thread were interested in seeing my article from 2003 on this topic.

I have placed the original article text and my unpublished rebuttal letter here: http://swoop.skydiveworld.com/c_article/aad_article_background.htm

As stated on the "background" page, I don't have access to the letter to the editor which was written by a company representative.
TroyK

"Free your mind, and your ass will follow" - George Clinton

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Broken link.

I think the link got messed up by a copy-and-paste rather than right-click and select "Copy Link" (so that the whole URL is copied, rather than the condensed version with ellipsis)



Yup... that's exactly what happened. Fixed now (in my posts).
TroyK

"Free your mind, and your ass will follow" - George Clinton

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Bill,

I agree about the testing being more complex, but this part:

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Trying to extrapolate a great deal of information from that one parameter (like end of freefall or resumption of freefall) is just not that simple.



Airtec creates quite a thorough investigation from returned units presently, including orientation, altitude and rate of fall prior to activation, so I still believe the data to implement my idea is already available within the unit.
.



It doesn't matter how much processing and analyzing the unit does, it is STILL restricted to knowing only about pressure and time and making inferences from those data based on the best guess of the programmer as to how to interpret them. The sensor is located in the turbulent wake of a bluff body of unspecified size and shape (the skydiver) in an unknown attitude. To the best of my knowledge there is no orientation sensor present.
...

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

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Orientation is extrapolated from the changes in pressure vs. time, i.e. they can tell if the jumper was stable or tumbling, but not whether they were falling stable back-to-earth vs. face-to-earth.



You can't do that with just a piezo pressure sensor and a timer. You'd need a gyroscope or something that provides inertial reference. Now you're getting into a very expensive area, and something that's going to be more complicated and require more maintenance.
Sky, Muff Bro, Rodriguez Bro, and
Bastion of Purity and Innocence!™

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Orientation is extrapolated from the changes in pressure vs. time, i.e. they can tell if the jumper was stable or tumbling, but not whether they were falling stable back-to-earth vs. face-to-earth.



Given a change in air pressure, you can extrapolate either a change in orientation or a change in altitude. You can not accurately do both.

While we don't know a lot about how the CYPRES algorithms work, we do know that they try to do what I just said can't be done. Since physics says they can't do it, they end up settling for what seems to be a pretty good approximation.

It's a fine point - but a CYPRES does not measure orientation, it infers it with a suitable margin of error.

_Am
__

You put the fun in "funnel" - craichead.

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You can't do that with just a piezo pressure sensor and a timer.



No, you also need a microprocessor and a software program, or a fairly complex analog computer. The result will not be an exact altitude reading, but it will be close enough for acceptable safety margins. It's been demonstrated many, many times by Airtec.

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