sducoach 0 #1 May 12, 2003 airtec.cc/productfiles.htm Student Cypres, 750' AGL @ 29 MPH Expert Cypres, 750' AGL @ 78MPH Tandem Cypres 1900' AGL @ 78 MPH Blues, J.E.James 4:8 Quote Share this post Link to post Share on other sites
kevin922 0 #2 May 12, 2003 Quote airtec.cc/productfiles.htm Student Cypres, 750' AGL @ 29 MPH Expert Cypres, 750' AGL @ 78MPH Tandem Cypres 1900' AGL @ 78 MPH Blues, J.E. It's semi true, student cypreses will activate @ 1000 feet if you are decending slower than freefall but greater than 29 mph. The incident in question about the no pull would be correct however, it would activate at 750. Kevin Quote Share this post Link to post Share on other sites
sducoach 0 #3 May 12, 2003 Please go to cypres-usa.com/english_users.pdf you will see that the activation altitude for the student cypres is 750' AGL. The activation altitude is "split" to include and cover a student who below 1000' AGL has deployed (slowed down below freefall rates) and cut's away at a low altitude. The expert cypres requires freefall rate down to 130' AGL then should not activate below that altitude The miss-information is that the student cypress will activate at 1000' AGL. Only if you have deployed/slowed down prior to that altitude and then accelerate to over 29 MPH. Blues, J.E.James 4:8 Quote Share this post Link to post Share on other sites
motherhucker 0 #4 May 12, 2003 Quote airtec.cc/productfiles.htm Student Cypres, 750' AGL @ 29 MPH Expert Cypres, 750' AGL @ 78MPH Tandem Cypres 1900' AGL @ 78 MPH Remember that these altitudes (the way I understand it) are accounting for the burble the unit sits in on your back, so if your back is seeing clean air ie, a long snivel or a stand up, it will fire somewhat higher--somewhere around ~1000ft agl. correct me if I'm wrong. Quote Share this post Link to post Share on other sites
kevin922 0 #5 May 12, 2003 Quote Please go to cypres-usa.com/english_users.pdf you will see that the activation altitude for the student cypres is 750' AGL. The activation altitude is "split" to include and cover a student who below 1000' AGL has deployed (slowed down below freefall rates) and cut's away at a low altitude. The expert cypres requires freefall rate down to 130' AGL then should not activate below that altitude The miss-information is that the student cypress will activate at 1000' AGL. Only if you have deployed/slowed down prior to that altitude and then accelerate to over 29 MPH. Blues, J.E. Um, that is EXACTLY what i Just stated. I read it straight from the manual just like you did. Your initial post was only half correct, you didn't state the scenerio where the student cypress WILL fire at 1000 feet. Again this really is a side note since the incident in question was a no pull which I indicated earlier the student cypres would fire at 750 in that scenerio. Quote Share this post Link to post Share on other sites
skydiverek 63 #6 May 12, 2003 QuoteThe expert cypres requires freefall rate down to 130' AGL then should not activate below that altitude I have always wondered - why? What's the reason for not activating below 130'? I know at that altitude the reserve will not have time to open fully, but if you are gonna go in, why not have it deployed by CYPRES anyways, maybe it is gonna snag the tree, or something? Quote Share this post Link to post Share on other sites
diverdriver 5 #7 May 12, 2003 QuoteI have always wondered - why? What's the reason for not activating below 130'? I know at that altitude the reserve will not have time to open fully, but if you are gonna go in, why not have it deployed by CYPRES anyways, maybe it is gonna snag the tree, or something? This logic would inhibit a misfire possibly say during a hook turn. Not that hook turns were prevelent during the design and development period of the early Cypres. Quote Share this post Link to post Share on other sites
billvon 2,991 #8 May 12, 2003 >I have always wondered - why? What's the reason for not activating below 130'? It may be better, from a liability point of view, for the cypres to appear to be off after a fatality rather than have the cypres fire too low to save the jumper's life. Bryan Burke has claimed that, in that situation, the cypres will switch off rather than remain on; I have not verified that yet (and can't until I have a timed-out cypres to experiment on.) Quote Share this post Link to post Share on other sites
PhillyKev 0 #9 May 12, 2003 No matter how reliable they are, there's always the chance one will mis fire. There's absolutely no point in it firing under 100', it won't do you any good any way, so why have the risk of an accidental deployment right when you're about to land. Quote Share this post Link to post Share on other sites
billvon 2,991 #10 May 12, 2003 >There's absolutely no point in it firing under 100', it won't do you any > good any way, so why have the risk of an accidental deployment > right when you're about to land. If barometric altimeters (especially ones mounted on your back) were that accurate I would agree. Quote Share this post Link to post Share on other sites
Hooknswoop 19 #11 May 12, 2003 Expert Cypres: Fires at 750 feet at 78 mph (114.4 fps) or more Student Cypres: Fires at 750 feet at 29 mph (42.5fps) or more (However, should the rate of descent be lower than that of free-fall but still above the limit of 29 mph, then student Cypres activates the EOS (cutter) when the altitude decreases below 1000 feet above ground level.) Tandem Cypres: Fires at 1900 feet at 78 mph (114.4 fps) or more A student or expert Cypres will not work if the aircraft is exited before it reaches 1500 feet and the Tandem Cypres will not work if the aircraft is exited before reaching 3000 feet. The Cypres ceases operation below approximately 130 feet AGL. Hook Quote Share this post Link to post Share on other sites
Clownburner 0 #12 May 12, 2003 To quote directly from the CYPRES user manual (bold text is my highlighting): Quote2.2 Student CYPRES The Student CYPRES can be recognized by the yellow button with the imprint "Student" on the control unit. It will activate the EOS when the rate of descent exceeds 29mph (13m/sec). The activation altitude is split. In the case of rate of descent being equal to that of freefall the opening altitude is at approx. 750 feet, being the same as with Expert CYPRES. However, should the rate of descent be lower than that of freefall but still above the limit of 29mph (e.g. with partially opened canopy), then Student CYPRES activates the EOS when the altitude decreases below 1000 feet above ground level. The student will then have some more time to prepare for landing.7CP#1 | BTR#2 | Payaso en fuego Rodriguez "I want hot chicks in my boobies!"- McBeth Quote Share this post Link to post Share on other sites
sducoach 0 #13 May 13, 2003 Last time guys. The activation altitude is 750' AGL UNLESS there is a deceleration and then an acceleration back to 29 MPH. If you do not pull, where does the student cypres activate the EOS? Airtec's info states the activation altitude is 750' AGL however they do have the feature that will "split" the altitude up to 1000' AGL IF the deceleration occurs. This is a great example of the "misconception" of the student cypres activation altitude. Blues, J.E.James 4:8 Quote Share this post Link to post Share on other sites
crazy 0 #14 May 13, 2003 QuoteThis logic would inhibit a misfire possibly say during a hook turn. 130 feet! I hope nobody buys this one. A change of barometric pressure would easily fool the altimeter by 50 feet. Add to this the error of the altimeter, and your AAD is still on when you reach the maximum vertical speed after your hook turn. Quote Not that hook turns were prevelent during the design and development period of the early Cypres. Yes, and they still have no convincing answer about this. Why should we believe that a cypres won't fire after a hook turn, while it is so easy to set a pro-dytter off?-- Come Skydive Asia Quote Share this post Link to post Share on other sites
Clownburner 0 #15 May 13, 2003 If that's correct, the user manual is unclear, which is exactly where the source of the 'misperception' is.7CP#1 | BTR#2 | Payaso en fuego Rodriguez "I want hot chicks in my boobies!"- McBeth Quote Share this post Link to post Share on other sites
USPA 0 #16 May 13, 2003 I wonder where you get this information from.. This is NOT what the manual states, neither is it what Airtec tolded us, when we changed the freefall student rigs from FXC to student Cypres....The trouble with skydiving; If you stink at it and continue to jump, you'll die. If you're good at it and continue to jump, you'll see a lot of friends die... Quote Share this post Link to post Share on other sites
billvon 2,991 #17 May 13, 2003 >The activation altitude is 750' AGL UNLESS there is a deceleration > and then an acceleration back to 29 MPH. If you do not pull, where > does the student cypres activate the EOS? 750 feet if you never pull. Next question - let's say you pull at 1800 and are beginning to decelerate. You have a four second snivel and decelerate to 30mph by the time you reach 1000 feet. What will the cypres do? Let's look a the manual: ". . .Should the rate of descent be lower than that of freefall but still above the limit of 29mph (e.g. with partially opened canopy), then Student CYPRES activates the EOS when the altitude decreases below 1000 feet above ground level." So the cypres will fire at 1000 feet if you pull low. Add the usual 300 foot difference the cypres sees when you get stood up, and a cypres firing at 1300 feet would not be that unusual. Quote Share this post Link to post Share on other sites
skycat 0 #18 May 13, 2003 QuoteYes, and they still have no convincing answer about this. Why should we believe that a cypres won't fire after a hook turn, while it is so easy to set a pro-dytter off? Derek has emailed them several times about doing some test jumps for them under his 60 to see if he would/could cause it to fire. They haven't responded back to him yet. Last I heard he was thinking about calling them.Fly it like you stole it! Quote Share this post Link to post Share on other sites
Ron 10 #19 May 13, 2003 QuoteYes, and they still have no convincing answer about this. Why should we believe that a cypres won't fire after a hook turn, while it is so easy to set a pro-dytter off? Anyone ever heard of a CYPRES firing durring a hook? I have not. Ron"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334 Quote Share this post Link to post Share on other sites
billvon 2,991 #20 May 13, 2003 Speaking of which - if anyone has a timed-out cypres I will take it off their hands for $50 or so. I'm planning to use it for chamber tests so I can see what a cypres really does. Quote Share this post Link to post Share on other sites
Hooknswoop 19 #21 May 13, 2003 Bill- I have a test chamber, I just need to either get the altimeter fixed or get a new one. SSK told me that they didn't know if an Expert Cypres would fire at 3.1:1, so I ditched mine. I would really like to put one in a fanny pack and jump it to see if it fires. I'm still working on that. I'll also take a 12 year, 3+ month old Cypres. Hook Quote Share this post Link to post Share on other sites
riddler 0 #22 May 14, 2003 Quote However, should the rate of descent be lower than that of freefall but still above the limit of 29mph Can someone answer what exactly is slower than free-fall but still above 29mph? Numeric value? 100 MPH? 50 MPH? I'm a free-flyer, so anything below 150 is slower than my typical fall-rate Trapped on the surface of a sphere. XKCD Quote Share this post Link to post Share on other sites
sundevil777 102 #23 May 14, 2003 QuoteLast time guys. The activation altitude is 750' AGL UNLESS there is a deceleration and then an acceleration back to 29 MPH. If you do not pull, where does the student cypres activate the EOS? Where did you get the bit about the 'acceleration' back to 29 mph? I don't see anything like that in their manual.People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am Quote Share this post Link to post Share on other sites
diverdriver 5 #24 May 14, 2003 QuoteSo the cypres will fire at 1000 feet if you pull low. Add the usual 300 foot difference the cypres sees when you get stood up, and a cypres firing at 1300 feet would not be that unusual. Actually Bill I don't think 1,300 is the correct altitude. I think most here assume that 1,000 feet is some sort of intended trip mark. I don't think it is. Expert Cypres is really set to fire at 1,000' AGL. Agree with me? But because of the pressure signature on the back of someone in freefall it actually fires at 750 feet AGL. So, the student Cypres is set to fire at 29mph or higher. What would happen if the student is stood up with a deployment or partial mal? They slow down so that pressure signature is now near ambient. So, we come back to the actual preset 1,000 feet fire altitude. But now with the student Cypres if they cutaway or have a high speed spinning mal but are stood up the Cypres will activate at 1,000' AGL like it was originally programmed to do. So, I don't believe the student Cypres could "misfire" at 1,300 feet the way you describe it. The way the Cypres manual reads it makes it seem that there is a secondary logic going on that changes the fire altitude to 1,000 feet when in fact that is the only fire altitude set in there. It's the change in the jumpers position that changes the firing parameters and thus creating the two statements in the manual. I feel this is just a "marketing statement" that is causing all this confusion. But that's just my take on all this.Chris Schindler www.diverdriver.com ATP/D-19012 FB #4125 Quote Share this post Link to post Share on other sites
billvon 2,991 #25 May 14, 2003 > So, I don't believe the student Cypres could "misfire" at 1,300 feet >the way you describe it. I think what you said is essentially correct, however, I do not think that they have taken the burble into account on one deployment scenario and not the other. That means that the expert cypres fires at a pressure altitude of 1000 feet, meaning 700 feet in normal freefall. The student cypres fires at 1300 feet at the lower speed, meaning a deployment at 1000 feet in normal freefall (or 1300 feet under a mal.) Although you normally wouldn't see this speed in normal freefall, you certainly could after a low cutaway. Add to that the normal error in the cypres's baro sensor and it could be even higher than that. That's my impression; proof one way or another may have to wait until Hook or I can get our hands on a timed-out student cypres. Quote Share this post Link to post Share on other sites
