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jacketsdb23

Ultra Performance Canopies & AAD

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throwaway456789

The Cypres in this video (https://www.youtube.com/watch?v=pLqaMGIqWe4) was a standard version - anyways, also the standard version is not supposed to fire below 130ft. I think it is pretty clear, that the activation altitude seen was well below 130ft - so how much are you going to trust in the parameters set in the Cypres?



From Billvon about this video:

"Question: I do not understand why the reserve PC emerges at like 20 feet.

Answer from BILLVON: swoopers can hit speeds near freefall during the turn. At that point the burble that commonly forms behind people in freefall will result in the AAD seeing an altitude increase of up to 300 feet. (This is taken into account by "upping" the activation altitude by 300 feet in back-mounted AAD's.)

Thus the sequence can proceed like this:

Swooper at 1000 feet. AAD reads 1000 feet.
Swooper starts turn and accelerates to near-freefall speeds.
Swooper is at 500 feet in the turn. AAD reads 800 feet. (500 feet + 300 foot burble)
Swooper begins to plane out.
Swooper is at 100 feet and starting to slow down. AAD reads 400 feet. (100 feet +300 foot burble.)
As swooper slows, burble is reduced. In rapid succession, AAD reads 250 feet (50 feet + 200 foot burble) and then 170 feet (20 feet + 150 foot burble.) This exceeds both the firing altitude limits (130 feet) and vertical speed limits (114 feet per second) and the AAD fires."

MORE:
http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=4167133#4167133

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throwaway456789




I looked up the patent that describes the functionality of the Cypres unit (http://www.google.com/patents/US5825667) and did not really like what I saw. While there are two sensors (acceleration and pressure) to calculate altitude and speed, differing values do not lead to a shutdown of the unit, but to the value beeing calculated as an average. That means one malfunctioning sensor will not directly be detected but distort the measured altitude, which can lead to a fire outside the set limits. Also as far as I have found out, there is only one CPU built inside, giving another single point of failure.



This is a video of a late model Cypres I unit being taken apart, (early models used a different Pressure Sensor. I have one opened up some where around here).

I would be willing to bet that the only difference between this design and the Cypres II design is better power management and perhaps smaller parts / better use of real estate.

https://www.youtube.com/watch?v=9-wzPTiLz5c

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That's a great theory and may be correct but it doesn't invalidate the point that the current crop of AADs are not nearly as reliable as people seem to think. The industry seems content to blame all misfires on "user error" but I don't think that's good enough. Imagine if a car manufacturer had airbags that deployed when the driver took a turn too fast. Do you think they could get away with blaming "user error"?

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raymod2

That's a great theory and may be correct but it doesn't invalidate the point that the current crop of AADs are not nearly as reliable as people seem to think. The industry seems content to blame all misfires on "user error" but I don't think that's good enough. Imagine if a car manufacturer had airbags that deployed when the driver took a turn too fast. Do you think they could get away with blaming "user error"?



Are there any documented non-user errors / device errors? From what I have seen and read all "misfires" where under small canopies doing a high performance landing while approaching fire speed.

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One of the AADs had an error causing it to lock up, but look like everything was working correctly on the display. Caused a huge recall recently.

Another one had a manufacturing issue where the cutters didn't have the blades installed.

Several other examples I can think of.

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Zlew

One of the AADs had an error causing it to lock up, but look like everything was working correctly on the display. Caused a huge recall recently.

Another one had a manufacturing issue where the cutters didn't have the blades installed.

Several other examples I can think of.



Yes, I've heard of those. In context of this topic I was however thinking more of misfires which happened e.g. during normal landing in conditions nowhere near firing.

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piisfish

what I would like would be a "regular" AAD with a manual on/off switch I can operate easily after main opening.



The problem with an option like that would be that the unit can be turned off by accident. AAD manufacturers create their products having to counterbalance two major risks caused by malfunctions:

1. AAD firing when it should not fire
vs.
2. AAD not firing when it should fire

While in my opininion (and I think I am not alone with it) malfunction #1 is much worse than #2 (saying I will prefer an AAD that does not fire at all and accept an accidental shutdown to one that fires when it should not), manufacturers try to keep the functionalty of the AAD under all circumstances and will accept an accidental fire. As already said - from a technical and safety point of view this doesn't make sense to me. From a marketing and PR point of view it makes a lot of sense. Imagine the uproar that would go through the skydiving community if an AAD did not fire at all even though it was switched on correctly? The typical "The unit functioned as it was designed" would not count anymore then. An unintended fire from time to time is not that difficult to handle. The manufacturer can always blame the skydiver on using a unit although it was known in before that limits could have been exceeded. You cannot do that, when an AAD was not to fire at all. Imagine all the skydivers/customers running away from that specific AAD brand, to switch to one that has not yet failed to activate. Imagine all the money that an AAD manufacturer would loose.

If you look into the Cypres patent I posted before you can see, that the AAD actually knows when the canopy is open. It would be easy to shut it down as soon as this happened but of course you run the risk to accidently shut down if you missdetect a canopy opening or in case of a cutaway. The same goes about a manual off-switch, even though this is less likely to happen. So while I fully support your idea of an AAD the switches off as soon as the canopy is open, I do not think that any of the current manufacturers is ever going to sell something like this due to the high image and marketing risk.

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skydiverek

***what I would like would be a "regular" AAD with a manual on/off switch I can operate easily after main opening.



ASTRA had that.

correct, and I have seen first hand video of those misfiring (long ago). Two 360 degree turns under a 120 sq ft canopy at 1500 feet...2 out.

One of the problems with the Astrsa was batteries dying when people forgot to turn them off at the end of the weekend.

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skydiverek

***what I would like would be a "regular" AAD with a manual on/off switch I can operate easily after main opening.



ASTRA had that.that, and nice colors. Any Idea of why the Astra didn't "take the market" ?

Cypres with a kill switch ? please ?
scissors beat paper, paper beat rock, rock beat wingsuit - KarlM

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Marketing and over all perception of a product by persons that in general do not understand safety system logic, especially when high levels of emotion are associated, definitely are a factor IMOP. I am getting ready to pull on my hip boots and start to wade into the quicksand my self.

Another aspect that plays a powerful role is cultural. I have had some very interesting discussions with jumpers from other countries about how much “choice” the PIC should be allowed to have. As I am American who believes that the individual has the freedom to make what ever decision they so choose, allowing the PIC the option to have the AAD “disarm” (lets say, as my AAD will keep recording data until after landing) after a good main opening, is perfectly ok to me. Now if the jumper wishes to have the AAD available should a situation where it would be beneficial to have an operational AAD occur, they can choose that as well. I received a message from a HP Pilot who had a friend that had to cutaway after a good main opening, and after taking off his chest strap which made it difficult to find the reserve handle after cutting away and the AAD fired saving him.

I will be very surprised if Airtec adopts the Argus swoop mode operation of shutting down after opening. Perhaps the control interface could be put on the mud flap so one could shut it down themselves after opening?

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Quote

I received a message from a HP Pilot who had a friend that had to cutaway after a good main opening, and after taking off his chest strap which made it difficult to find the reserve handle after cutting away and the AAD fired saving him.



Why aren't RSL's being pushed more for this function? I don't understand the reservation of having an RSL with a HP canopy. I've never heard of anyone spinning in on line twists on a reserve due to an RSL induced reserve opening on a HP canopy.

AAD is for opening a canopy if you are knocked out prior to activating a parachute.

RSL is for a reserve deployment after cutting away.

To me its really that simple. A kill switch (automated or manual) for the cypres would be amazing. Or your new AAD. Its time.
Losers make excuses, Winners make it happen
God is Good
Beer is Great
Swoopers are crazy.

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jacketsdb23


Why aren't RSL's being pushed more for this function? I don't understand the reservation of having an RSL with a HP canopy. I've never heard of anyone spinning in on line twists on a reserve due to an RSL induced reserve opening on a HP canopy.

AAD is for opening a canopy if you are knocked out prior to activating a parachute.

RSL is for a reserve deployment after cutting away.

To me its really that simple.



Everyone has their reasons for or against a RSL with a small main and reserve, just like everyone has their reasons for or against AADs. I am coming to the conclusion that RSLs and AADs are like Politics and Religion lol

jacketsdb23


A kill switch (automated or manual) for the cypres would be amazing. Or your new AAD. Its time.



I agree it is time as well.

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piisfish

******what I would like would be a "regular" AAD with a manual on/off switch I can operate easily after main opening.



ASTRA had that.that, and nice colors. Any Idea of why the Astra didn't "take the market" ?

Cypres with a kill switch ? please ?

Personal theory why Astras never took off:

- Battery issues
- Need to turn unit off after opening if you had a slightly aggressive canopy / or expecting big turns
- Not hidden (back then, people would never think of mandating AADs... There was still some level of mistrust of them, and advertizing you had one was not cool... Although they were starting to become standard)
Remster

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@jacketsdb23 - I agree with you. If you want a safety device to ensure reserve deployment after a cutaway the RSL is the right choice, not an AAD.

I don't think a manual disarm switch is the best solution, though. It will be too easy for the canopy pilot to forget to disarm it (and that would actually qualify as "user error"). It would be better for the AAD to disarm itself after main deployment. I think that can be done very reliably.

1) arm when freefall is detected above 2000 feet
2) disarm when exiting freefall at any altitude

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I think that can be done very reliably.



I think so too. I believe Argus proved that, they certainly had many swoop mode AADs without a fire (to my knowledge) due to the unit not disarming after a canopy opening.

With the choices in the market today, im seriously considering a used Argus.
Losers make excuses, Winners make it happen
God is Good
Beer is Great
Swoopers are crazy.

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I think g sensor for freefall is not that useful. When you get back to freefall, you will accelerate at exactly 1g after you chop.

There isn't anything "thrusting" you towards the ground except gravity. The same happens when you exit the plane.

Your speed changes when you chop or exit the plane, but not your acceleration. the acceleretion will be constant until you deploy.

It can help to determine that you deployed your parachute, maybe more accurate for Wingsuiters than only pressure sensors.

A g sensor may be useful for determinating that you started a HP turn under canopy.

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mrkeske

I think g sensor for freefall is not that useful. When you get back to freefall, you will accelerate at exactly 1g after you chop.

There isn't anything "thrusting" you towards the ground except gravity. The same happens when you exit the plane.

Your speed changes when you chop or exit the plane, but not your acceleration. the acceleretion will be constant until you deploy.

It can help to determine that you deployed your parachute, maybe more accurate for Wingsuiters than only pressure sensors.

A g sensor may be useful for determinating that you started a HP turn under canopy.



If it were easy this discussion would not be taking place lol...

There is a lot that needs to be considered as you and others have pointed out, that one sensor, or another, isn't enough to do the job with enough confidence head room, if you know what I mean.

There are so many overlapping conditions that can exist during a jump that identifying what is actually going on requires a bit of "black magic".

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So I finally did it.

I put a used Argus into my container with a Petra 68. Its on Swoop Mode and I verify that before each jump. So far so good.

As I stated earlier, I'm OK with the failure mode of not working when it should. Per the mfg., unit stops monitoring when it detects an open canopy.

Has anyone heard of a Swoop Mode Argus firing with an open main? I have heard of an Argus firing when the mode was switched after coming back from a repack - but I'm not aware of a misfire while in swoop mode.
Losers make excuses, Winners make it happen
God is Good
Beer is Great
Swoopers are crazy.

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Back in days of yore when I had a Cypres I . I relocated the control unit behind the mudflap of my rig (when Adrian died) with an extra clear pouch I had laying around. I would shut it off under canopy when I wanted to do a higher multiple rotation set up. Not sure of the legality of it for everyone. However, am allowed to "experiment" as a rigger as long as no one else jumps my rig...
death,as men call him, ends what they call men
-but beauty is more now than dying’s when

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