Is this true???

[Megatron 0]

Somebody posted this in the "stupid things I have done" thread.:

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"Oh and the 750 foot Cypres altitude we've all been told about is for a "belly to earth" orientation. The Cypres will fire much higher when you are head or foot first towards the planet."

I was under the impression that the criteria for the Cypress to fire was that one had to be below 750ft and traveling faster than 76mph.
So if my speed in freefall is significantly higher than belly-to-earth speed the Cypress will fire at a higher altitude??? That doesnt seem right does it?

[phoenixlpr 0]

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I was under the impression that the criteria for the Cypress to fire was that one had to be below 750ft and traveling faster than 76mph.
So if my speed in freefall is significantly higher than belly-to-earth speed the Cypress will fire at a higher altitude??? That doesnt seem right does it?

Do not stress about this! You suppose to be under a working, flying canopy over 600m. Having or not a Cypress should not matter. Keep on reading the "Waiting for the Cypress thread..."

[mnealtx 0]

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So if my speed in freefall is significantly higher than belly-to-earth speed the Cypress will fire at a higher altitude???

Incorrect - it's not the speed, it's the pressure. There are two triggers in the cypres software, speed and pressure. The cypres uses the pressure sensor readings to determine speed and altitude. In a belly-to-earth position, your burble affects the pressure sensor reading. In a sit/stand/headdown, that burble isn't there, so the pressure sensor trips at a higher altitude (I've seen ~1000 feet mentioned in threads, but don't know how accurate that is).

Regardless, you SHOULDN'T be waiting on the cypres to fire, obviously!!!

Mike
I love you, Shannon and Jim.
POPS 9708 , SCR 14706

[pilotdave 0]

It's really important to know this about your AAD. It's not because you might blow through 1000 feet head down or in a sit. If you do that, who cares if your cypres fires a little high? It matters if you screw up and pull your main down below 1500 feet or so. As your main snivels, you will be stood up but continue to descend at high speed for a little while. If you're still doing over 76mph vertically as you go through about 1200 feet, your cypres may fire (for the reason mike explained above). That would give you a 2-out. That's why you need to go for your reserve significantly higher than 750 feet if you find yourself in freefall down low.

Problem is that it's a tough decision and most people will instinctively go for their mains, not their reserves, when they're in a hurry to get a canopy out. But the point is, when you come down under a 2-out and you swear you pulled by 1200, your cypres didn't misfire... it did what it was expected to do.

Dave

[billvon 2,995]

>So if my speed in freefall is significantly higher than belly-to-earth speed the
>Cypress will fire at a higher altitude??? That doesnt seem right does it?

1) It does 'seem right' to me because at higher speeds you need more time for your reserve to slow you down. However:

2) The REASON it fires higher is that when you are belly to earth your "back" reads 300-400 feet higher than your front, and your AAD is on your back. When you are at 1100 feet the AAD thinks you are really at 700 if you are back to earth.

[jsaxton 0]

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So if my speed in freefall is significantly higher than belly-to-earth speed the Cypress will fire at a higher altitude???

Incorrect - it's not the speed, it's the pressure. There are two triggers in the cypres software, pressure and TIME.

Fixed it for you

[Megatron 0]

thanks for the clarification. I pull kinda high to begin with (~4.5) so unless some shit does down I don't see myself in freefall under 2500ft. Definitely a good point about the risk of a 2-out when pulling the main low. Lowest I've ever pulled was at 2500 during a low hop & pop...my Neptune showed 1900 deployment. Although I was B2E the whole time that's still a bit too close for comfort. From now on I'm going for the reserve under 1500 as a rule.

[erdnarob 1]

As I explained it in several posts in this forum here are some facts about AAD's

Providing you are at 78 MPH or faster:
A Cypres (expert mode) will fired at 750 feet, a Vigil (pro mode) at 840 feet, an Argus (expert mode) at 800 feet and an Astra at 1000 feet when you are in a belly to earth position.

In belly to earth position there is a partial vacuum between chest and back (less pressure in your back due to partial vacuum) that difference is about equal to 260 feet of altitude (remember less pressure on an altimeter means higher altitude) then:
If you are standing up or head down there is not anymore a differential pressure between your chest and your back (where is your AAD).
Therefore and providing you are at 78 MPH or more:
A cypres (expert) will fire at 750 + 260 = 1010 feet (a Cypres requires first you reach 1500 feet to get ready to fire)
A Vigil (Pro mode) will fire at 840 + 260 = 1100 feet (a Vigil requires first you reach plus or minus 150 feet to get ready to fire)
An Argus (expert mode) will fire at 800 + 260 = 1060 feet (an Argus requires first you reach 1400 feet to get ready to fire)
An Astra will fire at 1000 + 260 = 1260 feet (the Astra requires first you reach 1700 feet to get ready to fire)

Learn from others mistakes, you will never live long enough to make them all.

[mnealtx 0]

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So if my speed in freefall is significantly higher than belly-to-earth speed the Cypress will fire at a higher altitude???

Incorrect - it's not the speed, it's the pressure. There are two triggers in the cypres software, pressure and TIME.

Fixed it for you

LOL...thanks.

Mike
I love you, Shannon and Jim.
POPS 9708 , SCR 14706

[erdnarob 1]

Agree with you. Pressure will provide the altitude like does an altimeter while "rate of change of pressure with respect to the time" will give you the "rate of change of altitude with respect to the time" = speed

That means, in an AAD you have an aneroid or pressure chamber and a timer (and hopefully a good software).

Learn from others mistakes, you will never live long enough to make them all.