dgw 8 #1 December 11, 2006 From the incidents forum: >-doesn't allow for a collapsable pilot chute Note that this is only because no one has built such a pilot chute yet. Heck, the simple "big grommet" mod would effectively give you a collapsible PC for a ripcord-based system. *** What the hell is this, please? Quote Share this post Link to post Share on other sites
riggermick 6 #2 December 11, 2006 QuoteFrom the incidents forum: >-doesn't allow for a collapsable pilot chute Note that this is only because no one has built such a pilot chute yet. Heck, the simple "big grommet" mod would effectively give you a collapsible PC for a ripcord-based system. *** What the hell is this, please? Big brass number 8 grommet seated on the top of your deployment bag instead of a smaller one (either S/S or brass). It's the grommet that your bridle passes through. A number 8 will allow the deployment bag to slide along the bridle after the canopy has cleared the bag. When the bag reaches the pilot chute it will slide 50 to 75% up the mesh section of said pilot chute effectivly chokeing it off, presto collapsed pilot chute!!! The down side: Over a relativly short time it will destroy your pilot chute, requiring you to buy a new one much sooner. Another down side is, it is MUCH easier to get some canopy top skin material caught in the grommet along with the bridal which will increase your chances for canopy top skin damage or a potential cut away from a catastrophic failure or enough material at the right place to cause an uncontrollable spin. There you have it! If you are a careful packer the malfunction/ damage can be reduced/ eliminted, but the poor old pilot chute will still get the snot beaten out if it every time. It's you're call. Mick. Quote Share this post Link to post Share on other sites
dgw 8 #3 December 11, 2006 Thank you. The 'Big Grommet' theory had put me in mind of a donut shaped universe. It's an intriguing idea. I'm surprised it didn't catch on. (The big grommet). I guess it's an idea from back in the day, when pilot chute drag was always a minor consideration, even with round (fat) jumpers. Quote Share this post Link to post Share on other sites
slotperfect 7 #4 December 11, 2006 If you are talking about a "ripcord based system," that means that the main pilot chute has an internal spring. Therefore the "big grommet mod" would not work anyway.Arrive Safely John Quote Share this post Link to post Share on other sites
Gene03 0 #5 December 11, 2006 Simple, economical and reliable...NOT. While it does work there are more problems. The bag sliding up the bridle wears out the pilot chute, bridle and the bag faster than a kill line p/c. Another problem is you are putting more mass on the end of an eight foot lever and increases the chance of the pilot chute/bag combo whipping over the front, rear or even side of the canopy and getting caught in the lines. As Mick said it's your call but I really wouldn't recommend it.“The only fool bigger than the person who knows it all is the person who argues with him. Stanislaw Jerzy Lec quotes (Polish writer, poet and satirist 1906-1966) Quote Share this post Link to post Share on other sites
riggermick 6 #6 December 11, 2006 QuoteThank you. The 'Big Grommet' theory had put me in mind of a donut shaped universe. It's an intriguing idea. I'm surprised it didn't catch on. (The big grommet). I guess it's an idea from back in the day, when pilot chute drag was always a minor consideration, even with round jumpers. It was popular a few (quite a few) years ago, but most jumpers like their gear to last a while and not to have to spend time and money on maintainence or replacement when they could otherwise be giving it to DZ operators for actual jumps. Mick. Quote Share this post Link to post Share on other sites
dgw 8 #7 December 11, 2006 The post was based on something Billvon said in the Incidents forum, relating to a spring loaded pilotchute. Riggermick's post sounds reasonable for both spring and non-spring loaded pilotchutes? Quote Share this post Link to post Share on other sites
slotperfect 7 #8 December 12, 2006 QuoteRiggermick's post sounds reasonable for both spring and non-spring loaded pilotchutes? Just how is a grommet going to allow the bag to slide over the spring of a pilot chute? The interior diameter of a #8 grommet isn't more than about an inch.Arrive Safely John Quote Share this post Link to post Share on other sites
Gene03 0 #9 December 12, 2006 Correct. The grommet doesn't slide over the spring. The inverted deployment bag sits at the base of the p/c and deflects air around the p/c, effectively "killing" it. Dependent on size of bag and p/c and other factors it works better some times than other times.“The only fool bigger than the person who knows it all is the person who argues with him. Stanislaw Jerzy Lec quotes (Polish writer, poet and satirist 1906-1966) Quote Share this post Link to post Share on other sites
BrianM 1 #10 December 12, 2006 QuoteIt was popular a few (quite a few) years ago It's still common for retractable PC's on CRW rigs."It's amazing what you can learn while you're not talking." - Skydivesg Quote Share this post Link to post Share on other sites
stratostar 5 #11 December 12, 2006 Yes, but that is not what is being discussed.you can't pay for kids schoolin' with love of skydiving! ~ Airtwardo Quote Share this post Link to post Share on other sites
stratostar 5 #12 December 12, 2006 I have a few PC's with POD's that have no #8 in them and slide up and cover a fair amount of a spring loaded pilot chute, but a POD is much bigger then a D-bag, I also have a hand deploy PC and the POD slides to a stop to kill the non kill line pilot chute, not that it matters much on a PC and it keeps the POD from becoming a "freebag". All very "modern" old school set up's and works well, but I can't see any reason to use this today with gear on the market these days.you can't pay for kids schoolin' with love of skydiving! ~ Airtwardo Quote Share this post Link to post Share on other sites
lekstrom10k 0 #13 December 12, 2006 The large grommet was originally for the rings and ropes system when you had at least two strands of 5/8 tubular webbing passing through the hole. Also when you had Para-Commanders crown lines stowed on top . Some bags stowed them inside with no grommet. Most people didnt want a pilot chute weighted down with the bag dropping into their steering lines or "A" lines on a rock and roll opening. Quote Share this post Link to post Share on other sites
billvon 2,400 #14 December 12, 2006 >Just how is a grommet going to allow the bag to slide over the spring of a pilot chute? It's not; the grommet will stop at the base of the spring, leaving the rest of the bag to drape around the pilot chute, reducing drag. It's not nearly as good as a true collapsible but is simple and dirt-cheap. As Mick mentioned it will wear the bridle and PC base faster. If one really was interested in doing a ripcord activated main, you'd probably end up with a more traditional kill-line system, with the kill line functioning like a drawstring around the PC's skirt rather than connecting to the apex. One advantage of this would be the ability to move the AAD cutter from the reserve to the main, greatly reducing the chances of a two-out scenario. Quote Share this post Link to post Share on other sites
IanHarrop 37 #15 December 12, 2006 QuoteOne advantage of this would be the ability to move the AAD cutter from the reserve to the main, greatly reducing the chances of a two-out scenario. Changes in lines and canopies have resulted in slower openings being the norm these days. As such, would moving the AAD cutter to the main also require higher activation of the AAD?"Where troubles melt like lemon drops, away above the chimney tops, that's where you'll find me" Dorothy Quote Share this post Link to post Share on other sites
billvon 2,400 #16 December 12, 2006 >As such, would moving the AAD cutter to the main also require higher >activation of the AAD? Would depend on the canopy. On my current canopy (Nitro 108) it wouldn't, because it opens reliably in 300-400 feet. On a Spectre? Perhaps. Fortunately, AAD's with higher activation altitudes are available. Heck, if you have the room, you could get an old FXC! Set them to whatever altitude you'd like, reset them right there if they fire after opening. Quote Share this post Link to post Share on other sites
dgw 8 #17 December 12, 2006 Thanks guys - very interesting. Quote Share this post Link to post Share on other sites
