JohnSherman

Ski, All round parachutes oscillate, in fact their angle of oscillation is published for each model. That is why we cut holes in them, to direct the flow and reduce the oscillation. Drag devices don't go into oscillation phase until they go into tow. Tow means that the device being loaded with more load than can support. Like when a bag gets stuck in the container. That's when the tug of war begins and you see the oscillation. That is the condition in the photos you posted but the pilot chute isn't draging, it isn't dancing, it isn't jerking on the bridle like a dog playing tug, it is just lazyly being drug through the air with no resistance. It should be violently oscillating with a very high amplitude and frequency. I have wind tunnel tested simular designes in the NASA Ames 7x9 wind tunnel. See:https://www.youtube.com/watch?v=Zva4gHVX_zI While the specific PC was not the one tested it is simular to the 3rd one. Additionally, the jumper himself said the bag was trapped in the container and he was more verticle than on his back. I hope the drag of the pilot chute was at least enough to stand him up and get him off his back if he ever was. Until this pilot chute is tested and it's "Effective Square Footage" published and deemed acceptable it should be grounded in all cases. Oh 1MT: The OP calls for release of the videos required during certification testing. I had forgot about that. Don't you think it would be a good idea. john

It was named after Steve Helwedg, the designer of the shape. Steve was most reciently seen packing kevlar booster recovery parachutes for the Space Shuttle boosters.

It's all of the above. I can't tell you exactly what is wrong with each rig on each failure because I haven't had the opporitunity to examine and test it. In sone cases it is mostly one just one weak component like the pilot chute and in some cases it is on rigs with the maine closed, maybe extraction force and in some a little of both. I do know it is happening and I believe it is pervasive. See my post #3 here: http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=4463200;sb=post_latest_reply;so=ASC;forum_view=forum_view_collapsed;;page=unread#unread It offers additional insite to my position. BTW: The BPS is studing the adoption of a procedure to screen for the problem.

Please excuse me for butting in but: 1st Clue: https://www.youtube.com/watch?v=vaYQ6iP8zlg 2nd Clue: https://www.youtube.com/watch?v=-5_KLch6ziA 3rd Clue: https://www.youtube.com/watch?v=Zva4gHVX_zI 4th Clue: A history of 15 previous accidents with simular circumstances: AAD fired, reserve failed to deploy. Question to all: During this time, how many and what kinds of rigs have successfully deployed a reserve under simular circumstances? They can't all be failing. If we knew the answer to this question (information AAD manufacturers could supply) we could understand the depth, of the impact, these events are having.

Your post gives me an excuse to follow up on a post in the original thread. On that thread I Posted on post #130: -------------------------------------------------------------------------------- Quote -------------------------------------------------------------------------------- How about raising activation heights to 1500 feet for students and 1000 feet for expert .. add extra margin of safety. why 750 feet ? hang on I think mr Booth has already raised this !! -------------------------------------------------------------------------------- I replied: "When you understand the problem you will understand that raising the altitude will not help. Those reserves wouldn't open in 2000 feet. If you can't get the bag out of the container you can't get the canopy out of the bag." ------------------------------------ From that post I recieved several PM's asking why I thought that way. I answered with references to the balance of evidence. However I failed to refer to the best proof, "the eye in the sky". for that I make amens here by reposting the fololowing link: https://www.youtube.com/watch?v=vaYQ6iP8zlg

Take your choice. http://www.jcometals.com/handles/handles_index.htm

Both scenerios do the same damage. They blow the boundry layer off. Unfortunitely is is not "Laminar Flow". It is "Turbulant flow". So soon you forget. The internal pressure is not greater at higher speeds. In fact the differential pressure is less at high speeds. Making it easier to detach the boundry layer. "The point of greatest lift is just prior to an impending stall". The point of greatest lift is also the point of the greatest pressure differential. This point is the most resistive to rotors et. al. A wing is a wing. The physics are the same. Pilot perceptions are extremely unreliable.

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This is a total mis-understanding about the internal cell pressure on a Ram-Air. The internal cell pressure on a Ram-Air is ambient. In that air is a non-compressible liquid it has ony 2 levels of pressure: Static & Dynamic. Ambient is Static corrected for enviromental variables. Dynamic however requires the additional component of Velocity. Dynamic Pressure "Q" = 1/2RHO V^2. There is no circulation or air movemnet inside a cell, therefore no velocity. Wing loading is not an issue in turbulance, but it is sure more scary. In turbulance the correct procedure is to apply brakes approximately equal to your deployment brakes. This does cause the pressure differential between the inside and the outside to increase. The point of greatest lift or of the greatest pressure differential is just before a pending stall. This high differential will cause the boundary layer to be stronger and resist detaching, which is what happens when that rotar blowes it off of the top of your canopy causing a relaxisation of the wing. Your braked toggle position will not absolutly prevent this detachment but it does put you in the best position for an instant recovery. You should not loose significant altitude using this method.

The red reinforcement tape was a mis-diagonosis by the folks who used it. History has proven that. The root cause for the Type 17 failure was the failure to fold the selvage edge under where it contacted the middle ring. Allowing the selvage edge to be exposed to the place where the middle and harness ring come together, is the root cause. At this place, when the rings load, the two rings actually work like a guillotine slicing the type 17. I had a pile of rejected Type 17 risers (Someone had burned a hole too big for the grommet) and they were not usable. I put each one, in turn in the dyno. I could not fail them. Then I exposed the selvage edge and they failed. Under a glass the failed surface was like a scissor had cut it. I repeated this experiment a large number of times. I published a paper in 1993 on the subject but people would rather listen to uninformed “gurus” speculation than read: http://www.jumpshack.com/default.asp?CategoryID=TECH&PageID=T17FAILURE&SortBy=DATE_D The red reinforcement does only one thing. It reduces the mechanical advantage of the ring set due to the increase thickness of the webbing. Parachute Labs. has never had a Type 17 riser failure. Risers with the red tape have failed. Lubrication of the cable is paramount. Lubrication reduces friction all along the length of the cable. Most importantly at the last 8 inches or so. There is no amount of dirt or gunk within the housing that can cause the cable to bind. The tolerances are too great. The housings are totally unnecessary. Loop load is the killer for un lubricated cables. Do the test in post #3 of this thread.

Wing loading is for landing info not openings. You will find this hard to believe but: if you double the wing load you will only increase the opening force by 10%. This guy has a line dump problem. If a canopy opens soft once all one needs to do is control the variables and it will open soft every time.

If your openings were really hard you can see it on your 3 rings. Look at the front side of the middle ring where it contacts the harness ring. It is the back side if the set is assembled. Hard openings are indicated by the denting or "Brunnelling" of the middle ring where it contacts the harness ring. These dents can be measured to tell the extent of the opening. I would look to the line stow system on my d-bag for relief.

I still make them that way.

I don't think so. But a lubed yellow cable would have. I have had this happen to me. I also have had to put out a reserve without being able to cut away. I did an extensive investigation and found what I am telling you.

I don't know what you are trying to accomplish but Hard housing are not necessary and if not installed correctly, dangerous. They accomplish nothing. If you will keep your yellow release lubricated you will never have a difficult pull. Assuming your risers will pass the ring alignment test, all of your release resistance is at the nylon loop which the yellow cable goes through. The friction between the loop and the cable can vary as much as 100% depending upon lubrication. Lube your cable and forget the inserts. To test do this: In a suspended harness bypass the loop and insert a lubed cable directly into the channel on the riser. Retain the loops with a temporary pin. Perform the 2 bloke test: One person hanging on each side of the person in the harness. Twist up the riser until the rings cone together at your chest. Pull the release handle. Observe the force required. Pull either of the temp pins and observe the force required. Repeat the test with the cable going through the loop. Repeat with housings in the riser channels if you are curious and have the time. You will have your answer before you get here.

On a Racer I would put the AAD pin between the 2 existing pins with the butt or heal of the AAD pin flush with the bottom if the top pin. The AAD Pin would be orientated 180 opposite to the top regular pin. That puts the pusher between the 2 pins. I haven't looked at all instulations. However, I am confident it could be worked out using this new technique. I have seen and have video of the pusher configured for a 1 pin reserve and a 1 pin main. The AAD pin could be directly above or below the pin closes to the handle. Cable routing and protection is part of the mounting braketry. Don't know 'bout the Dual Hawks. But I like challenges.

Only a fool would answer No. Never say never. Having said that, let me say that I have not encountered one yet. The Mk 2000 pusher worked well and had no reports of failures of this nature. I would not have suspected the cutters would do what they did. My crystal ball has fogged. Thus the reason for conceptual thinking. Help me!

You are correct. However, my reference is to the corrective action and how our drogue bridle attachment works. Our drogue is loaded directly to the passengers’ hips bypassing the rig and the TI. The drogue directly suspends the passenger. If the passenger gets their legs out in front of them by bending at the waist (jack knifing) and the TI can't get their legs around the passenger’s legs and pull them back, then the TI must not arch. The TI has to put out the drogue at this point. The drogue due to the suspension will pull the passenger back into the proper orientation. You preamble is appreciated and embraced. Thank you. Next Subject: TSO requirements. I had planned to refer you to Manley Butler’s book about "How to get a TSO" so as to avoid a diatribe. However other posts subsequent to yours have indicated a desire for the long version. The simple answer is that there is no provision for Certification of an AAD component. TS-112 is a guide for manufacturers to approve the installation only, not for Certification of the device. Quite frankly it was a waste of time to write it as it serves no useful purpose except as cover. Beginning of diatribe: The TSO system is divided into several parts. “A” is for “Airframe” “B” is for Engines. The “C” in TSO-C-23x is in reference to the category of “Accessories” for the aircraft. A parachute system is considered an aircraft accessory. The number 23 is for parachutes on the list of accessories, basically emergency parachutes. However, the main parachute is considered primary and does not require certification while the life saving part is the reserve and harness and does require certification. FAR Part 1 “Definitions” is where we begin. A parachute is defined as 6 major components with a bag or sleeve as optional. No mention of AADs, not that there couldn’t be. The TSO itself is simply a letter referring to an industry standard which defines the system and component qualification tests. In our case PIA TS-135. TS-135 has no language for an AAD component as there is no such thing as an AAD defined as a part of a parachute system, and it probably should have. Therefore there is no standard or metric to which you may certify such a device. I invite you to generate some. The test need only to be performance type and durability tests and would not get into the inner working of the unit. Maybe it should have a POST (Power On Self Test) code and maybe a hot and cold soak to prove the environmental capability of the unit. Maybe an impact test to prove durability, etc. Additionally, once the qualification tests are satisfactorily met you may apply to the FAA for authorization to identify the equipment as “Certificated”. That application is called the Data Package. It must include drawings adequate to reproduce the tested models as well as a statement of conformance to qualification tests and of the existence of an FAA approved QC plan and any and all manuals. Once approved this package become law and is difficult to change retroactively. The problem at this point becomes conceptual. The first rule of AADs is that: “It must not interfere with the normal function of the reserve”. Any cutter is “potentially” capable of failing to cut and jamming the system. Therefore cutters are excluded. Some configurations are not as sensitive to this. A bit of history: Back in the day, SSE was making the MK 2000. I had one and I decided to wear it when I moved to Deland. I was an I/E, and all that stuff and I believed in AADs as I still do. I had lost 2 of my best friends (team mates) to mid-airs. I was one of the moving forces to bring AADs to tandem. I wore it to set an example to younger jumpers. That is until the DZ owner came to me and said “Loose that Thing”. Obviously, I bucked at that but eventually I was beating a dead horse and I stopped using it. Its funny how 30 years ago a DZ owner was telling a customer that they should “loose that thing” (one which would not affect the reserve function) and today some are requiring them which might impair reserve function. How times change! Remember, it had a pyrotechnic fired “pusher”, big and clumsy. I previously had conversations with the folks at SSE about the potential use of cutters. They referred to the military experience on cutters in cargo parachutes which was not acceptable for human life protection. They said that the military would never accept cutters. Maybe it was PR. Helmut (CYPRES) was from Germany and did not have the benefit of the military prejudice toward cutters so it was natural that he selected them for use. We all bought into his good work. Then along came another vendor who used a slightly different cutter which proved fatal. I never dreamed that this could happen but it did. It was at that time I came to realize the extent of the conceptual problem. A cutter, no matter how good, can fail the system. Therefore cutters are excluded from consideration The AC-105-2c had language which could have been used to prosecute the rig manufacturer of Tandem rigs if the AAD failed. It is from that language that I requested my waiver. The more recent AC105-2d has clarified that language to mean that only the installation need be approved by the manufacturer not the AAD itself. I still have the waiver. I am attaching a document/waiver, which was prepared for the purpose of demonstrated to DZ operators, who require AAD, that they are playing with fire by requiring same. At this point in our development AADs must be a personal choice. Informed consent is the phrase which comes to mind. I dream of the day when we can have an AAD TSO’ed “which will not interfere with the normal function of”.

Wrong! Racer Tandems have a waiver which waves the mandatory requirement for an AAD which is approved by the manufacturer. We have no capability to approve AADs and certainly are not willing to take responsibility for such an instulation which might fail the reserve. All Racer Tandems I know of do have AADs but if they fail it is not our fault. It is a "Black Box" after market instulation and the responsibility of the owner. Additionally, The Racer Tandem is not prone to the "Side Spin" problem due to the drogue suspension system. No! It is far more complicated than that.

For your convience! https://www.youtube.com/watch?v=luBce2n-7VA

When I was very young, I was in Times Square New York and there right above me was Jim smoking a Camel and blowing smoke rings. The smoke rings were about 20 feet in diameter and came from a billboard which pictured Jim in his jump suit. I was impressed. I finally met Jim at the World meet in Gap and got to know my hero. I wish I could find the pictures we took then. If I do I will post one.

This is not a real problem. We have tested for it and while the final design completely encloses the pin, the test conditions did not and the power was enough to drive even a bent pin out. Remember the rig must not have more than 22 pounds pull force and if the pin is bent you shouldn't be jumping it. When was the last time you heard about a no pull because of a bent pin in a nylon loop?

They have been working on it. However, ther just isn't enough time or money to make regular, steady progress. They know how but can't get to it what with all of the other projects. I do know one thing. Cutters have failed and can't be conceptually trusted. I would be happy to forward all I know about cutters/pushers to anyone who would like to take the project forward.

The Argus Cutter has a hole in the end of it. The piston in shapped like an arc punch, concave in the middle. This configuration can be used for a pin pusher, wasn't much good as a cutter. While the stroke is about .5 inches it has enough power to drive the pin out, I have videos. I would want a stroke of at least 1 inch. It would push against an extra pin on the ripcord which is rotated in the opposite direction of the existing pin, still pointing down. This puts all of the mechanism on the outside of the container. A bracket to hold the pusher would be no problem.

The AAd manufacturers were invited to write a standard for AAD's. They could not do it. They had many excuses why it couldn't be done. They need motivation. What motivation do they have now? The world wide market is shared by basically 2 manufacturers. They don't need certification, why spend the time and money on something which will only complicate their lives. This is not to say they arn't doing a fine job, but why change? My personal position is that they should do away with cutters and come up with a miniture "pusher"which has no posibility of "interfering with the normal operation of". Cutters can and have interfered with the normal operation of some rigs. I believe in AAD's but we need improvement.