JohnSherman

The first half is correct but it doesn't matter when or what they put in the manual it is not binding. Nothing they say in the manual is binding. Only a Service Bullitin stating safety concerns and requesting an Airworthyneess Directive and the issuance of that Directive can change the life span. Mike Truffer (Skydiving Mag) did the research some years ago. If a rig is to have a service life it must be specified in the data package which accompinies the original application. Changing the manual does nothing. The FAA points out, in the last paragraph, it must be by "Service Bullitin" stating Safety Concerns and requesting an "Airworthyness Directive. Just putting it in the manual does nothing I applaude the work done by Mike and now Randy. It is the correct rule. Once PIA got a letter from the French Federation stating their equipment had a 20 year life and requesting to know what the life span on American equipment was. PIA responded "120 days" which was the duration of the "Inspection Cycle" at that time.

I would also reccommend a test for acid.

I mean Ambient not Dynamic pressure. Dynamic pressure "Q" is the force on the bottom skin. Which is the product of speed and density. The internal pressure is equal to the surrounding atmospheric pressure which has no increase due to speed. Its whatever the barometer reads at that point. The top skin has a reduced pressure because of the circulation of flow. Think of it as the inside being neutral with the outside being a battle between Newton and Bernoulli. Newton on the bottom and Bernoulli on the top. "Q" never gets past the bow wake.

The INTERNAL pressure of a ram air never exceed ambient! Neither during opening or full inflation. It is the external pressure which reduces and because the ambient is greater we have a differential which causes the inflated ridgity. Line burn does not cause blowouts. In My total experience with Ram air canopies I have never seen a line burn except from a accidentally pre-packed malfunction. The greatest force occure at "Snatch". The line attachment knot tightnest will relate to the location of the bridle attachment and the amount of brakes to a lesser extent.

Doesn't look like one of our bags. Ours are configured the same but with the "Bag Retainer Line" sewn to the inside of the bag. This piece seems to be missing on yours. John

Granted it doesn't change the deployment but it does change the opening. I would say the Key word is "Speed". When you track it is really nothing but a vertical dive with a small amount of hotizontal deflection, certainly more with a wing suit. Tracking speeds can reach up over 200 MPH achieving a Dynamic pressure of near 100 pound per square foot. Normal "Q" or dynamic pressire is about 33 pfs. So we tripple the force of the air and if you don't think that won't roll your socks down when you open, enjoy.

THe Temple of Heaven Parachute Company of China used to make a single surface, flat rigged cargo canopy. It looked like on of our ram-air canopys with no top skin or ribs. I don't believe it was steerable. I have a brochure on it. Oh, I almost forgot Jerry, the Pioneer copy of the Cloud was a Titan. I had one and thought the reason for the single tail was that they ran out of fabric.

I totally agree. There may be is some quarters but it is idle speculation. It has never happened.

We always have. Send us your container size and we will fill it. Send it to: Suzie@Jumpshack.com

Rubber/Stow bands do much more than retain the lines. They release the lines sequentially causing a smoother and more gradual acceleration to speed of the mass. "Snatch" for the most of us. This makes for smoother more controlled softer openings. Thus the reason for the SPEED Bag. There has never been either a bag lock or a line dump on a SPEED bag in its 10 years of experience on a main or reserve. The Air Force academy reduced its malfunction rate from about 14/year to 1 in 3 years with SPEED bag copies. With the SPEED bag you don't have to choose which type of mal you would prefer to deal with. John Sherman

Thanks for the links. They are simular and interesting but non of them look like the MARD is doing the deploying. They look like a reserve pilot chute deployment after a cutaway. One was especially interesting as the pair were on their backs after the bag lock fully developed. This is the position I believe is the most dangerous for the RSL function.

Lee, You are correct about the rate at bridle stretch. My bad! That rate brings the "Q" up to about 3 pounds per sq. ft. However, film study of cutaways (see the one on my home page) shows the pilot chute on its side while the bridle plays out. It takes almost exactly 1 second from launch to load (when the PC turns and grabs air). I attribute this to the total length and find it interestingly coincidental. However, my interest here is because this is the critical time when the bag should be extracted. Additionally there is a "Snatch" involved which assists extraction. I ignore the snatch in my calculations and consider it a bonus toward extraction. My bridles are folded under the side flaps and I see no retention occurring. In the film it seems to meter out into the air stream. There is no tension on it. My focus on all this is to provide metrics for designers to predict their bag extraction requirements. It is also to provide metrics with which riggers may test and certify that the bag will indeed extract without having to pull it out by hand. We ARE on the same page. As an aside: The pilot chute in the subject incident looks a lot like the Sigma from the bottom. Is It? If it is and if it has the same effective sq. ft. then it is dragging about 7 pounds, about the weight of most reserves, so any container hang up would inhibit it from extracting. Can't comment on paragraph 2 as I have never seen it- only calculated it. I suggest you reef your drogue with a cutter as NASA does. MARDS: well we agree on the Effective Square footage of the Vector/Sigma pilot chute. NASA measured it at 2.33 Square feet. That’s about half of a normal pilot chute. However, because of the unknown/variable drag value of a malfunctioned main and collapsed drogue no engineer would ever depend on it. Additionally, I say the pilot chute alone will handle the job if it is of competent design. See: http://www.youtube.com/watch?v=FtNKXDW0Ixo This was a tandem pair weighing over 550 pounds and an actual malfunction on a commercial jump. Tandem is no different than sport, just a little heavier but within the same realm. Remember a drogue has less drag than a pilot chute, considerably less, I figure (measured) my drogue to drag about 90 pounds at terminal with a load of 375 pounds. My pilot chute drags about twice that. Strong's drogue is sure big but it doesn't drag much (about like mine). It's not supposed to. It's there to help compensate for the additional unexposed weight of the tandem pair. I don't know how you are going to get a tandem pair to speeds of 200 or more but all of the tests I have seen or done are where a tandem pair (two very heavy guys) could not get much over 170 no matter how hard they tried. When you strap two guys together their surface area is about the same from any angle. Certainly a solo jumper could go much faster. I can, and do, deploy a tandem reserve faster and more consistently with just a pilot chute than anyone can with any MARD, and do it at any speed. BTW: Have you, or anyone else for that matter, seen any MARD tests where a Tandem with a main bag lock and a collapsed drogue have been successfully deployed with a MARD? If you have, please forward them to me. John

I know you didn't mean for your statement to soud like this but people could read it and think that Power Racers mght have a risk of the pilot chute hesitating as it leaves the container. As I know you know and that the world knows this is not the case because the pilot chute is external and the only thing that causes "Burble " on it is air flow or lack of it. Just for the record.

Oh, Lee you ask so many questions. I will try to sort them out and answer them one by one. BTW: I am happy with a functionally designed container and I am the only one who has to be pleased. I don't make gear to look good, I make it to WORK! ( Drag Coefficient * Surface Area = Effective Square Feet) Of course this depends on what drag is available for the scenario encountered. If you are talking about cutaways we must assume a 20FPS ROD (minimum ROD for Mal'ed main) at about 2000 ft. The Dynamic pressure in that situation is 0.45 pounds per sq. ft. ( See:http://www.jumpshack.com/Q.htm Fortunately we have a bag, bridle & pilot chute which are about 16 feet in total length. The distance you fall in the first second after cutaway is 16 feet plus the distanced generated from the ROD of the mal’ed main (16+20=36FPS) the Dynamic pressure at that point has increased to about 1.45 pounds per sq. ft. OK, so you have a pound and a half per square foot of drag at the point you pilot chute grabs air. If you bag and canopy (the components to be extracted) weigh 15 pounds you will need a pilot chute with an effective square footage of 10. This assumes no container retention (Certainly some retention is necessary to maintain sequence). In all cases there is a "Snatch "component when the pilot chute takes air. This is a relationship between the mass and forces. If you were at terminal (33PSF) and your PC has 5.9 effective sq. footage, like mine, you would get just under 200 pounds of drag. With a 10 pound bag the "Snatch would be 20 G's (200 pounds drag /10 pound bag = 20 times the weight of the bag or 20 G's. At cutaway speeds, shown above, that snatch would be about 8.6G’s. A lower drag pilot chute will produce much lower snatch. When you apply this process to your situation you can begin to realize why you need such reinforcement. Remember the Solid rocket boosters of the space shuttle recovery parachutes.The drogue had a reefing on it which held the canopy in a "Squid" (Skirt held together) configuration until it slowed enough to open fully. A MARD on Tandem is the worst idea I have ever heard of. There is no scientific logic anywhere in that scenario. A MARD had a a variable drag component which can not be depended upon. Collapsed drogue, bag lock, on your back, RSL won't peel, you’re dead. My tandem has 20 years experience with a calculated 5 million jumps and 2 fatal incidents both of which were proven to be rigger/operator error. Everybody should be "Doing the Math"

A good rigger should be happy to apply his skills to inspect and pack your BASE rig, (for a fee) but they can't Certify it as it is usually not TSO'ed (Some are TSO'ed and they can be sealed and certified)

Absolutly not! Some of the largest pilotchutes in the industry have the lowest drag. My SRP will out drag any normal sized pilot chute made. If the design and construction are the same then your point is valid. Believe me they are not the same from manufacturer to manufacturer. I am pushing PIA to require the identification of the effective size of the pilot chute in square footage. They can then be compared. The solution to this problem is to require manufacturers to identify the maximinum allowable extraction effort for a given container. Additionally they should identify the effective size of a pilot chute which would do the job. This guys problem had nothing to do with him being on his back. And yes Virginia there is a history of this happening. If this had been an AAD activation it would have been number 16 in the ground. Get smart and stay away from these one pin cantilivered flap, over boxed rigs. They all have the same problem, each for a slightly different reason.

I will bet you have injured a leg, hip or ankle in your past. While you may think you have achieved a full recovery you still have diminished kinesthetic in that joint or member. You think you body is symmetrical while it isn't. This has been the root cause of all of the spinning jumpers I have caught and straightened out over the years. I have found film study and awareness are the best solutions. A good instructor is also beneficial.

Parachute Labs. has extensive data in this subject area. Exactly what do you want to know? We use a PDAS system which will record everyyhing you ask for on any given jump. See: http://www.jumpshack.com/product_images/PDAS%20Brocure.pdf. BTW: We provide these systems to the U.S. Air Force which they use for evaluations of their systems. Give me a specific request for data and we will try to provide it for you. If is involves equipment from a different manufacturer we would be happy to test it for a fee. John BTW: Ther are math models which do a fair job of predicting most of this type of thing.

Just for the record. The Racer doesn't need a MARD. It is just as fast with its normal Racer reserve deployment. See: http://www.youtube.com/watch?v=D-Le2feyqqU We did develope one about 15 years ago but found it to be no advantage with more complexity. The MARDs were developed to catch up with the Racer. The Classic Racer (there are 2 kinds) produced today has no real design changes from the original. At least non that I can think of. Oh yeah! we now use magnets instead of velcro to hold the SEALED riser covers closed. The Velcro was always the rap on the rig. It would wear out. The 2K3 Racer (the other kind) is fitted with trough type riser covers. A design we had great trouble with during development as the top of the riser cover wants to hold the reserve closed when the main is full. While other manufacturers are still having trouble with this we solved the problem, but I still prefer the original Sealed covers they don't interfear with anything. As to the caviets about the RSL. I will paraphrase one of my competitors who, when asked, said "There is nothing wrong with the Racer RSL if you will read and heed the manual." There have been less problems with the Racer RSL than the "Single Side Design" used on other rigs.

Here is the Formal Invite for the services for Ed. It was to big to upload here so I made a link to it: http://www.jumpshack.com/remembering%20Ed.pdf

There is data and understanding about opening forces. It is a complex subject. You can find technical understanding in Theo Kanacke's "Recovery Systems Design Guide". What you probably endured was Line Dump/Strip. This is when the lines are left in you container as the bag is lifted off. Caused by inadiquet line stows. The pilot chute generates about 20 G's as it jerks the bag out of the container. There is a great picture somewhere on this forum where the lines are 3 to 4 inches from the bottom of the bag during lift off. This demonstrates the differential of forces. When this happens the slider drops down the lines before the lines are tight. Canopy inflates with full benifit of the slider. That is why I always rubber band my slider to the canopy.

As an adendem to that article I would say that the drag of the reserve pilot chute should be sufficient to re-orientate the jumpers body to a normal extraction attitude. In other words the pilot chute should "Jerk" you around. From any angle it is the drag of the pilot chute vs. the bag extraction force when measured at it's lowest level. Jumpers should demand to know the "Effective Size" (Cd*So) of their pilot chutes. If the manufacturer can't tell you "Buy something else" John

Jumpers considering this thread must realize that all canopies are not the same. Rear riser input will cause a different response in one canopy from another. This is dependant upon trim or angle of attack. Flat trimmed canopies which glude well will probably stall and drop out of the air quicker than "Lawn Darts" which are already dropping out of the air quickly. KNOW YOUR CANOPY

The Racer owners manual say to retain the center of the silder to the "B" line attachmnet (or which ever attachment is closest). It say to do it on all canopies, main and reserve. The reason I have continuse to require this is to compensate for line dump. Line dump in and of it's self is not a bad thing. The reason it hurts is that when line dump does occur the silider is allowed to travel down the lines before the canopy begins inflation or even reached line streatch. This allows more "plate" inflation to occur at "Snatch" which will roll you socks down and take your shoes off. We used the "Sail or Pocket Slider" on our first generation tandem main. For about 10 years. It does work but it is inconistant. The Firebold doesn't require it. Sail sliders wont help on line dump. John

I recieved this E-mail from Nancy LaRiviere. She asked that I post it. _________________________________________ Dear Friends of Ed Miller, There will be three memorial celebrations for Lt. Col. Ed Miller, USMA (Ret.). All friends and fellow skydivers are invited to attend one or any of the events. July 29, 2012 - Elsinore There will be a brief ceremony, the skydive, and then testimonials for the video. Please be at Elsinore at 9:30 AM on Sunday, July 29th, to say "So long, Blue Skies" to our friend, Ed Miller. FFI: Pat Moorehead, skyfunone@aol.com or Marilyn Wuest at dmwuest2@aol.com" July 29, 2012 - Skydive Deland For those friends of Ed Miller who wish to participate in a last send off (ash) dive, I am planning to take him up on Sunday, July 29th, hour to be determined. Ed used to come to come to DeLand for POPS and SOS and other events. He was a great friend, a former Marine, all around wonderful guy. If you know of other friends of Ed’s not on my list, please forward this. His wife Cathy, is sending a portion of his ashes here. The plan is for simultaneous memorial dives in Florida, California and Texas as Ed had strong connections in all places. Part of him will also be laid to rest at Ft. Sam Houston. He was a travelin’ man.. August 12, 2012 - San Marcos, TX Ed's teammate on their world championship team, George Nisson will be organizing the memorial. If you would like to participate, please contact him at gmnisson@earthlink.net If you are near these dropzones on these dates, please join us to give Ed one last salute - Simper Fi. If you can't attend, please take a moment, smile and say goodbye in your own way. Nancy