ksaylor1

Course Director for my AFFIRC. Jumped with him a lot - not as much as many others here, but boy, were they memorable. What a character. Blue skies, Billy. Ken

D-bags are staging devices (working to ensure that things happen in a particular order) and stowing lines in rubber retainer bands (or similar) is a retarding method (working to make things happen more slowly than they otherwise would). Once a d-bag becomes "semi-stowless," openings are going to be less retarded than they otherwise would be. So yes, a semi-stowless d-bag, by its nature, is going to reach line stretch more quickly than a d-bag with lots of rubber band stows. What happens after that depends on the subtleties of how you folded the canopy and got it into the d-bag. Ken

[url]http://www.cypres-usa.com/english_maintenance.pdf ETA: Don't know how to make it clicky. ETA: Apparently, don't know how to make faces, either. Ken

If you truly have 79 jumps and 1 year in the sport, there's hope for us yet. At least some newbies know how their equipment works. I will remind you that it's CYPRES, not Cypress. It's a CYbernetic Parachute RElease System, not a tree. Ken

similar thread going on right now - AAD hidden functions. the water landing thing makes a lot of sense to me - submerging the unit just a little bit will appear to the cypres as a very rapid drop in altitude. if that was truly a design consideration, i just wish airtec would publish that rather than the "it wouldn't matter anyway" storyline that they put in the manual. it's pretty plausible, but i don't know if it's just a happy coincidence, or if they planned it that way. ken ETA: from page 11 of the CYPRES manual. Don't know why Chris D insists that it's not in the manual. Haven't looked for the water explanation, but here's the "party line" in black and white. It says "For this reason....." not "for this reason AND A COUPLE OF OTHERS....." 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 approx. 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 CYPRES will operate down to approx. 130 feet AGL. Below approx. 130 feet (approx. 40 meters) AGL opening is no longer useful. For this reason, CYPRES ceases operation below approximately 130 feet AGL.

If you submerge the unit (regardless of the filter) it will sense a rapid increase of pressure. At 15 cm below the water surface, the pressure will look like it is 100 meter below the ground level. To the unit, this will look like a rapid change of altitude and it may look like you are in freefall too close to the ground. To prevent two outs, the unit shuts itself off with some margin before it may be submerged. That's good information. Has Airtec confirmed that as the reason/a reason for the shutoff? Seems like a pretty benign reason to shut off at 130' AGL. So benign in fact, that I think most people would buy it if Airtec put that in the manual as the reason why the unit shuts off at 130' AGL. Makes me wonder why they stick with the "it wouldn't matter anyway" rationale in the manual. Most people don't like hearing "it wouldn't matter anyway, so we're just going to have the unit stop taking measurements." Ken

After exhaustive research (GOOGLEd "cypres 2 user manual", clicked on the first link, and read all the way to page 11), I found the following: "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 approx. 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 CYPRES will operate down to approx. 130 feet AGL. Below approx. 130 feet (approx. 40 meters) AGL opening is no longer useful. For this reason, CYPRES ceases operation below approximately 130 feet AGL." DZ Offset instructions start on page 19. Based on Airtec's intended use of the offset function, it follows that DZ offset "drags" the "does not fire below" altitude with it. ETA: Maybe it's not intuitive to everybody why this is. If you are taking off from and landing your parachute at the same location with the same elevation MSL, and you use the offset functionality for no reason other than to bump up your CYPRES' activation altitude, you are lying to the CYPRES as to where the ground is. You have told it that the ground where you will be landing is some number of feet/meters higher than where you are taking off from. The CYPRES doesn't know that you are lying to it. It trusts you. It keeps its "does not fire below" altitude at 130' above where you told it the ground is. Only the ground isn't there. The ground is the same place it always was, and the "does not fire below" altitude is actually (130' + the lie you told your CYPRES)' AGL. Shut off at 130' AGL for cutaways over water? That's the first time I've heard that. Maybe a precursor to the Speed model (i.e. did early swoopers hit max vertical velocity in their final 130' AGL and Airtec wanted to prevent two-outs?). I don't know anything about swooping, then or now. Ken

Maybe a post for a different forum. Ken

Maybe I'm just not thinking about it correctly, but the way I see it, the spring-loaded pilot chute pushes the closing flaps out of the way the same way whether it's allowed to do so by the loop being cut or by the pin being pulled. Either one of those events just allows the spring to do what springs do. I'm having a hard time wrapping my head around the "inside-out vs. outside-in" argument. I would need some 1000 fps video to compare what the two look like. Maybe DSE can help us out? Ken

You nailed it. You cutaway at some altitude that puts you reaching 78 mph at 850' AGL. But because you lied to your CYPRES and told it that the DZ was 750' higher than where you took off from, the CYPRES now believes that you're only at 100' AGL. The manual tells us that below (approximately) 130' AGL, the CYPRES won't fire, since it wouldn't make a difference anyway. If, however, you use the activation altitude adjustment (rather than the DZ offset), the CYPRES still "knows" where the ground really is, and the 130' critical altitude is still at 130'. Ken

I think the point he was trying to make is that there's quite a difference between changing the activation altitude on your AAD (if that's an option for you), and using the DZ offset function on your AAD (if that's an option for you). In one case, you're changing the activation altitude while every other critical function remains "stock." In the other case, you're shifting the entire range of critical altitudes "up." The OP was really just asking a technical question about his AAD, but I guess this thread can evolve into a philosophical debate about the "right" AAD activation altitude if that's what we want to do. Ken

I know this. That's why my reply was to pops' post, not to the OP. Thanks, though. Ken

You can take an expert model and bump the activation altitude up to (say) 1500' AGL using the offset functionality, but now you've moved the "does not fire below" altitude up to 880' AGL. If that's what you really want to do, drive on. Just know that there are second-order effects. Ken

QuoteHi, I just got a new safire 2 145, and although I can propack zero-p canopies with 100 plus jumps I have extreme difficulty with new canopies. So, I have been psycho packing it to get it in the bag. My openings have been pretty hard to instant. I may have been stowing with too short of stows and getting line dump, but I stowed the same way when I propacked my Safire 2 169 (100 jumps on canopy) and had super slow, super comfy 700-900 feet openings. Here's my psycho pack procedure and maybe if someone could please tell me if I'm doing something incorrectly I'd really appreciate it. No one psycho packs at my DZ, and I only do it to get it in the bag. First I set my brakes, then separate my lines and walk to the canopy. Fluff it out and count 9 end cells. Quote There's your problem. I've never had good openings on canopies with 9 end cells. Ken

EDIT: riggerrob beat me to the punch I check the PIA website (pia.com) just about every day. There's a substantial list, and new ones get posted to the list pretty quickly. Ken