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lilchief

should I, or shouldn't i...?

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I've recorded on several jumps, vertical speeds close to the activations speed on a cypres2 under canopy while doing a 270. I'm currently under a Samurai 136 at 1,65WL, and will be downsizeing to a Samurai 120 with at WL at 1.85 during this winter.

Close to the activation speed means 10mph down to 4mph below activation speed.

Since I'm already that close under a 136, how will it be under a 120? I believe that I need to be over the activation speed for more then a blink of an eye. But how long can I stay there before my cypres 2 fires? And should I, for safety reason, change to a Speed when downsizeing?

I've sendt an email regarding this issue to AIRTECH with no response.

My 270 is started at 530f and I'm practicing for CP nationals.
"Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been and there you long to return." - Da Vinci
www.lilchief.no

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how do you measure your speed



I use a razor and a digital scale, but I think that might be a completely different topic all together.

Personally I went through the same series of questions last year with myself. I was clocked with a radar in the neighborhood of 75mph after I had rounded out and was in a course a couple of times. It would reason to believe that I was going at least 3mph in my dive and that was on my old 120. When I downsized I took my Cypres1 out and put it in my wife's rig (whose cypres needed an eight year) and sold her cypres.

Then I bought a Velo 111.

Am I going fast enough high enough to pop a non-speed Cypres? I'm not 100% sure. I'm also not 100% sure I'm not.[:/]
--"When I die, may I be surrounded by scattered chrome and burning gasoline."

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oh..sorry guys. I let out the question it self...should I or shouldn't I get a speed cypres. since I'm so close to activation speed. :$

I measure using my altitrack and I read off both Skydiver and True airspeed and look at the lowest speed.

"Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been and there you long to return." - Da Vinci
www.lilchief.no

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I measure using my altitrack and I read off both Skydiver and True airspeed and look at the lowest speed.



the "Skydiver" airspeed is likely not reliable for anything under canopy. What are the speeds you are reading?

Can you give us a few examples? And to more specifically answer your question if you think you need a speed Cypress than get one.
"We've been looking for the enemy for some time now. We've finally found him. We're surrounded. That simplifies things." CP

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all speeds are in mph

jump nr 691
@ 37f - TAS: 69,42 SAS: 72,39

jump nr 672
@51f - TAS: 64,61 SAS: 67,53

jump nr 652
@363f - TAS: 69,32 SAS: 68,79

jump nr 651
@66f - TAS: 68,41 SAS: 71,12

jump nr 587
@77,56f - TAS: 69,00 SAS: 73,65

As you may see, these are getting close, but there are many jumps in between where I don't get those speeds. But it only takes one 270 that I nail perfect on a 120 and probably exceed activation speed. And then I'm toast. That spooks me! :S

"Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been and there you long to return." - Da Vinci
www.lilchief.no

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Airtec have stated that this is only a problem with MULTIPLE revolutions starting above 1000 feet.

There are also parameters for activation on how low you have to be with that speed.

Caution is a great thing, I think it's awesome that you're even aware of this potention issue (some really good skydivers still dont take it seriously, or know about it) - but I don't believe it's an issue for the wing you're flying, the altitude you're initiating at, the loading you're at, and the amount of rotations.

Blues,
Ian
Performance Designs Factory Team

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I have a faint memory of reading somewhere that the cypres will "deactivate" it self on 1000 feet, if the speed at that altitude is lower than 35m/s. Therefore speeds that exeed 35m/s after the unit has deactivated it self @ 1000ft wont matter.

Now that I was trying to check wheter this memory of mine is correct, I couldn´t find anything about it on airtec´s website. [:/]

Anyone know more about this ?

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It is of essential importance where the device that is recording your speed is located. If it is in your helmet or at your wrist - forget about the data - it isn´t worth anything! This is because any movement of head or hand will result in a dramatical change of the airflow that results in incorrect readings! To get resonable speeddata the device needs to be on your back (for example behing your rig) or somewhere in the center of your body/belly or upper legs. Lower legs or arms don´t work! This is not my opinion or my guesssing but what airtec told me. Give it a try and you´ll get lower readings. To activate the Cypres at your loading is very unlikly if not impossible. A lot of persons ask Airtec for the SpeedCypres but very few really need it. And the amount of persons that are better off without any Cypres at all (= too fast for the SpeedCypres) is VERY(!) small/little!

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Anyone know more about this ?



I was going thru the Adrian Nicholas thread and Fred Fugen thread and found out some one wrote:

"A cypres will fire between 750 feet and 120 feet, if vertical speeds exceed 35 m/s. "

It is still second hand info, so someone please correct this if it is not true.. But it seems my assumption of deactivating @ 1000ft was incorrect..

It seems to be more of a question on how long do you need to maintain that speed over 35m/s to have your cypres fire. (hence the requirement of multiple rotations in order to have a cypres fire)

Anyways, I wonder why some of you say that the number of people who might end up in cypres fires is very small ?

IMO small in this context is a vague term, since there are more and more people who load their canopies the same amount as Adrian did (or Fred does) and many of them are doing multiple rotations too..

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Airtech have a special unit that you can wear during your swoop that is recording all the data it takes during your decent. It is then possible to DL it into your computer to see how close you are to activation speed. I dont know if you need to go to them or they will send it out.

Bo
Bo Wienberg

vimeo.com/bowienberg

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I haven't read anything about the Cypres 2 deactivating itself under canopy. Maybe you're getting it confused with the Argus Swoop mode.
http://www.argus-aad.com/images/PDF/microsoft%20word%20-%2002.12.07argususermanual300607rev.pdf

About activating a Cypres under canopy, Airtec doesn't seem to give away all their secrets about the algoritm inside the Cypres.
http://cypres.cc/Sites/englisch/Skydiving_Small_Canopies.htm
"Even when reaching 78 mph for a moment, the Expert CYPRES would not activate. The reason is that CYPRES does much more than trigger based on measured descent rate and altitude, as it analyses the situation the skydiver is in"

Yes there are other things that complicate it like the burble effect while belly to earth versus any other orientation, but that could just make your Cypres fire a little bit higher, as high as 1050 feet or so. Also it doesn't arm until the airplane climbs to 1,500 feet.

No I don't think the OP is likely to fire his Cypres doing a 270 at a 1.85 wing loading.
http://www.cypres2.com/20050923update.pdf

http://www.cypres2.com/cypres2faq.htm
I want to get my Expert CYPRES 2 updated to the Speed version - how much is the cost and how long does it take?
- CYPRES 2 model conversion is done at no-charge, and takes about 2 weeks.

Read the manual
http://www.cypres2.com/userguide/CYPRES_2_users_guide_english.pdf

2.1 Expert CYPRES
The Expert CYPRES can be recognized by the red
button on the control unit.
It activates the release unit when it detects a rate
of descent higher than 78 mph (35 m/sec) at an
altitude of approx. 750 feet (approx. 225 meters)
above ground level (AGL). In the event of a
cutaway below this height CYPRES will operate
down to approx. 130 feet AGL, however activation
will not occur unless sufficient speed is obtained.
Below approx. 130 feet (approx. 40 meters) AGL
opening is no longer useful. For this reason,
CYPRES ceases operation below approximately
130 feet AGL.
BASE 1224, Senior Parachute Rigger, CPL ASEL IA, AGI, IGI
USPA Coach & UPT Tandem Instructor, PRO, Altimaster Field Support Representative

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Yes you are right. (and I believe I already corrected myself about the 1000ft deactivation issue.)

The question still remains how long do you need to maintain that speed over 35m/s in order to have to unit fire ? No one seems to know and airtec wont tell..

What we do know for a fact is that there has been at least 4 occasions when a cypers has fired under a HP canopy.. One of them resulting in death. Lots of people still jump expert cypres with similar wingloadings even today..

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I've recorded on several jumps, vertical speeds close to the activations speed on a cypres2 under canopy while doing a 270. I'm currently under a Samurai 136 at 1,65WL, and will be downsizeing to a Samurai 120 with at WL at 1.85 during this winter.

Close to the activation speed means 10mph down to 4mph below activation speed.

Since I'm already that close under a 136, how will it be under a 120? I believe that I need to be over the activation speed for more then a blink of an eye. But how long can I stay there before my cypres 2 fires? And should I, for safety reason, change to a Speed when downsizeing?

I've sendt an email regarding this issue to AIRTECH with no response.

My 270 is started at 530f and I'm practicing for CP nationals.



The PD team did testing with a datalogger. Even with very high wingloads, they found that you only reach the activation speed of a normal cypres when you did multiple rotations (aka bigger than 360°).

Conclusion, you only need a speedcypres (or the Argus Swoopmode) if you do a 450° or more.

CU

Jurgen

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