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when does cypress 2 arm itself

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I am just curious when the cypress arms itself. I was told that it decides at 1100 or 1200 feet and it will fire for sure (no matter what) at 750, as opposed to a vigil which decides at 800 and fires at 800. For example if you have a low pull at say 1000 feet will your cypress still fire ?

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If you toss your pilot chute at 1000' you will in all likelyhood see both your main and your reserve.

Have fun with that.

The vast majority of two-outs I have seen over the years have been due to loss of altitude awareness and pulling out the pilot chute too late.

What altitude are you pulling at now? With your jump numbers it should be well above any area where you should be concerned about your Cypress firing.

Blue Ones

Major Dad
CSPA D-579

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I'm guessing someone is confusing the 1500 foot arming altitude (which happens on the way up, not the way down). Why would it "decide" to fire so much higher than it fires? If firing was inevitable, why wait till 750? Doesn't do you much good to wait.

The 1100-1200 foot numbers probably come from the fact that if you're sniveling down that low, the cypres will probably calculate a lower altitude because the burble behind your back is gone and it will likely fire on you that high.

Dave

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"Arming" of a CYPRES usually refers to the altitude at which the CYPRES activates its self on the way up. That is 1500 feet. If you jump before reaching this altitude, it won't fire at all.

If you jump above 1500 feet, it will have armed, and will fire at (or below) 750 feet if your descent rate is 78mph or more (for Expert model).

Below 130 feet it won't fire at all.

So if you have made a normal jump and are are at terminal at 1000 and deploy, will your canopy inflate quickly enough to get you below 78mph at 750 feet? Probably only if you packed it slider down.:S

CYPRES 2 User Manual: http://www.cypres2.com/userguide/CYPRES_2_users_guide_english.pdf

"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

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As pilotdave stated, the CYPRES2 arms itself on the way up, 1500 feet above the intended landing altitude. At this point, once the unit reaches it's programmed rate of fall and actuation altitude (Expert model: 78 mph/750 FT), it will fire. This remains true until a very low altitude (which I believe is 130 FT) above the ground, at which point CYPRES2 will no longer fire if that speed is reached. Therefore, you have in effect a "firing window" of 620 FT (from 750 FT to 130 FT).

On a side note, some people like to set their CYPRES to fire higher, "tricking" it by adjusting the DZ offset from zero. What they don't realize is that they are dragging that entire 620 FT window up, not making it larger. For example, an Expert CYPRES set at "zero down" will fire between 750 and 130 FT. If a jumper were to want their CYPRES to fire around 1000 FT AGL instead, they would dial in "240 up" on their CYPRES. Now the CYPRES will fire between 990 FT and 370 FT. The moral of the story is that "tricking" a CYPRES is a bad idea.
Arrive Safely

John

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***Incorrent information, originally posted by me, removed so as not to create confusion - slotperfect***

Interesting. Got a source for that? The manual just says 1500 feet, I think...

EDIT:
"A Student, Expert or Speed CYPRES will not
work if the aircraft is exited before it reaches
1500 feet (450m) above the airfield takeoff
elevation and 1500 feet (450m) above the
intended dropzone elevation. In the case of a
Tandem CYPRES 3000 feet (900m) has to be
reached." (cypres2 manual)

So there are two arming altitudes. Must reach 1500 above the takeoff altitude and also 1500 above the landing altitude if an offset is used.

Dave

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So if you have made a normal jump and are are at terminal at 1000 and deploy, will your canopy inflate quickly enough to get you below 78mph at 750 feet? Probably only if you packed it slider down.



Point is, even if you pulled at say 1200 feet and did get below 78 mph before 750 feet, it will likely still fire. The cypres compensates for your burble when it calculates your altitude. When you're sniveling, the burble is gone and it will miscalculate your altitude. It will "see" 750 feet when you are considerably higher than that.

Dave

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Reading both user's guides, I find that your quote is the truth regarding the civilian CYPRES. My statement is true of the Military CYPRES - of that I am certain.

I edited my original post and your quote of it to remove the inaccuracy and avoid confusion.
Arrive Safely

John

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Good grief. I just pulled up a docs on the Mil version of the CYPRES to find there are SIXTEEN versions:

(1-pin or 2-pin) * (relative-pressure or absolute-pressure) * (4 different activation altitudes)
"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

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Point is, even if you pulled at say 1200 feet and did get below 78 mph before 750 feet, it will likely still fire. The cypres compensates for your burble when it calculates your altitude. When you're sniveling, the burble is gone and it will miscalculate your altitude. It will "see" 750 feet when you are considerably higher than that.



/head explodes

edit: Wait, so it automatically fires higher then 750ft on all occasions? It just assumes your PC is flapping around in your burble?

I'm REALLY confused.

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/head explodes

edit: Wait, so it automatically fires higher then 750ft on all occasions? It just assumes your PC is flapping around in your burble?

I'm REALLY confused.



The pressure inside the burble on your back is slightly lower than the ambient air around you. So an altimeter located on your back would read a higher altitude that the one on your wrist or chest-strap. If the AAD was designed to trigger at the pressure which occurs in clean air at 750', it would actually be triggering at a lower altitude because it is in the burble.

So the solution is that the AAD is really designed to trigger at the pressure of a higher altitude, which is the pressure expected to be in the burble on the back of a belly-flyer at 750'.

The complication is that if a person is being pulled upright by a deploying canopy, that removes the burble, and the AAD is suddenly seeing the higher pressure of the ambient air. Additionally, the pressure change from burble-to-ambient makes it momentarily seem as if the descent velocity is higher. These two issues can cause an AAD to fire above 750'.

How much over 750', I don't recall. It has been discussed in the past, and IIRC, a mfgr rep even chimed in to give some numbers.
"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

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Just to add to the confusion I have another legitimate question.

Let's say you climb from zero to 15k jump, successfully deploy a functional main at 3000ft then at 1800ft induce a line twist from hell and cutaway your main and now again find yourself in freefall at 1100ft will your cypress cut your reserve loop?

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Let's say you climb from zero to 15k jump, successfully deploy a functional main at 3000ft then at 1800ft induce a line twist from hell and cutaway your main and now again find yourself in freefall at 1100ft will your cypress cut your reserve loop?



If you exceed 78mph within the firing window, yes.
Do you want to have an ideagasm?

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I am just curious when the cypress arms itself. I was told that it decides at 1100 or 1200 feet and it will fire for sure (no matter what) at 750, as opposed to a vigil which decides at 800 and fires at 800. For example if you have a low pull at say 1000 feet will your cypress still fire ?



The concept of "deciding to fire" and then firing later is something that some people were spouting off when the vigil first came out to try and convince people to buy a vigil instead and it just isn't true.
~D
Where troubles melt like lemon drops Away above the chimney tops That's where you'll find me.
Swooping is taking one last poke at the bear before escaping it's cave - davelepka

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Let me try again. First of all I pull higher (3000), this just came up once. Protrack says 1100 feet for deployment, some one said that the cypress should have fired. I am just curious if lets say that a protrack marks 900 feet as the deployment, would you have two out ??

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Well since your protrack is not a Cypres and a Cypres is not a protrack I think we are trying to compare apples to oranges.

How does a protrack measure your opening altitude. At what rate of decent does it decide that your canopy is deployed?
"The restraining order says you're only allowed to touch me in freefall"
=P

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I am just curious when the cypress arms itself. I was told that it decides at 1100 or 1200 feet and it will fire for sure (no matter what) at 750, as opposed to a vigil which decides at 800 and fires at 800. For example if you have a low pull at say 1000 feet will your cypress still fire ?



The concept of "deciding to fire" and then firing later is something that some people were spouting off when the vigil first came out to try and convince people to buy a vigil instead and it just isn't true.



This story about deciding to fire already existed when Cypres was the only electronic AAD and has nothing to do with Vigil or Argus.
Lot's of people did not understand "the burble on the back" and tried to explain why a cypres fired at around 1000 ft when you were stood up under a snivelling canopy after a very low pull.

Gr

Jurgen

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Don't know about the protrack, but my neptune shows the deployment altitude a little below the bottom end of the deployment... always a LOT lower than where I pulled. I've checked the graph in paralog.

As long as your calculated speed is below 78 when your calculated altitude is below 750, your cypres will not fire. How that actually compares to what you see on the protrack would be pretty hard to quantify. Remember that the cypres doesn't "detect" a deployment like the protrack does. It simply has firing parameters.

Dave

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I dunno. They both have to calculate speed and altitude from pressure measurements. Probably both have to compensate for temperature at the solid state pressure sensor (no idea if that's true, but the neptune does). But the protrack has to also decide where you pulled and the cypres doesn't. I'd guess that the cypres code is written to a higher standard, but I'm not sure it's any more complex. Who knows though?

Dave

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