mark

For the aerodynamicists here: is "pressure gradient" a plausible definition of "boundary layer?" Is "boundary layer" the reason one feels little air flow near the door and progressively more as one exposes a finger or arm, or is it simply a function of surface area and lever arm? Mark

You don't have to take a course. Just pack 20 reserves, get your sign-offs, take the tests. I don't know of anyone with a "ram-air only" limitation on his certificate. I don't think it's ever been done. On the other hand, I don't know of any regulation which would prevent issuing a certificate with such a limitation. Even if the FAA was willing to issue such a limited certificate, they don't have a procedure for removing that limitation, except possibly by surrendering the certificate and going through the whole certification process a second time. Mark

John and Nancy are very smart people, but I do not understand the basis for this assertion. Lift is a function of forward speed: more speed results in more lift. As for boundary layer, in what sense is the "boundary layer" (in quotes because I don't know what the term means when applied to skydiving canopies -- I do know what the term means when applied to laminar flow) stronger at slower speeds? Finally, if a canopy has no deployment brake setting (Icarus tandem main, for example), is toggles all the way up the best way to go? And if a canopy has very deep deployment brake setting, near stall, like VR360 tandem reserve, how does one not fly at just above a stall if one is flying near deployment brake configuration? Mark

I'm sure Mr. Cooper thought the same thing. Mark

That's assuming, of course, that that canopy was being jumped as a reserve. It was common practice to take 28' reserves and convert them to sport mains by cutting vents and slots, and adding a sleeve. Although the converted military surplus container would have a data card pocket, it would be empty. But as long as we're hoping, we can hope that the data card is a personalized one. Some riggers used to print their own, a form of marketing or advertising. The card would last until the end of the pack cycle, 60 days, when the next rigger would throw it away and substitute his own -- no sense in advertising for the competition! Mark

Interesting idea! Hadn't thought of that. Any old time jumpers can to answer? Harnesses have never had data cards. Packs (the canopy and container, less the harness) have packing data cards. Nylon is not affected by mildew; it doesn't rot the way an organic material like silk does. It degrades in UV, i.e. in sunlight. A buried canopy would last a very long time. The data card, on the other hand, would be paper. The Tyvek cards we use now are much more recent. I don't think a paper card would be much more than pulp after 35 years of exposure. Folded up and still in the container pocket, it might give a little information, none useful in this case since if Cossey packed the chute, he would have written the serial number in his rigger logbook -- no need to check the data card to see if it was his pack. Mark

I need to correct my previous posts about what parachutes Cooper had. I wrote that he had two back-type reserves, 1 chest-type reserve, and 1 dummy chest-type. Based on Ckret's posts, Cooper in fact had: 1 back-type reserve (the NB-6), 1 back-mounted sport main (the Pioneer), 1 chest-type reserve, and 1 dummy. The reason the change is important is that the Pioneer sport system would have had rings on the front to accommodate the chest-type reserve. Cooper passed on the opportunity to use a two-parachute system with a steerable main, and instead chose to destroy the chest reserve and jump a single-parachute system. Mark

Yes, but IIRC, you have to have made three canopies to be considered a manufacturer... You recall incorrectly. The FAA has no definition of main parachute manufacturer. They don't really have a definition of reserve manufacturer, either, except insofar as it requires manufacture under a TSO. You don't actually have to make anything, let along three of anything; you just have to show that IF you made something, it would be identical to the test (approved) article. Mark

The FAA allows manufacturers to do maintenance on their own equipment. No rigger required. Mark

Sew-in on your Javelin would require either sewing through the backpad or partial disassembly of the container from the backpad. I think I'd try a three-sided pocket like you imagined at first, but extend the top so you have a velcro-secured envelope. Tack the corners of the pocket to the pack tray. The empty envelope won't add any significant bulk, but you should be able to insert a foam spacer when needed -- just make sure the envelope is roomy enough. Mark

The rig Cooper used did not have rings to attach a chest pack. So your theory is that Cooper hand-carried a chest pack out the door, held on to it through opening shock, landed with it, and buried it. Mark

Not unreasonable at all. A normally maintained 25-year-old nylon canopy in a pilot rig would meet the original specs. Nylon is not affected by mildew or rot, and is not much affected by age. Last year I came across a canopy from 1962 that had been in use in a pilot rig until 2002 or so. A frugal DZO might not see any reason to replace a canopy that wasn't going to be jumped. Mark

To your first question: yes. To your second question: sort of. Mark

No. He got two back-type reserves, one chest-type reserve, and one dummy that looked like a chest-type reserve. He did not get any main parachutes. Mark

Yes, you would be way wrong. Cooper didn't get any main parachutes. He got three reserve parachutes and a dummy parachute. Each rigger who packs parachute keeps the serial number of the canopy at least, so no need to unpack anything to re-record the number. Mark

C23b, c, and d are two-page letters that refer to specifications contained in NAS-804, AS8015A, and AS8015B respectively. Copies of the TSOs and the specifications are in the Parachute Rigger Handbook starting on page A-19. You can download a copy of the PRH from the FAA website, or go to the web site I cited in an earlier post. The TSO specs lay out the test standards; the second part of the TSO system is ensuring production articles are identical to test articles. Manufacturing inspections, traceability, and other quality control systems vary from manufacturer to manufacturer. As to following the manufacturer's instructions, I agree with MEL that we really ought to be doing that, not looking for ways to stretch the regulations to make them more convenient. At the same time, I'm not sure whether the FAA regards manufacturer instructions to fall into a category analogous to an Aircraft Owner Manual (a guide published by the manufacturer and not subject to FAA approval) or Pilot Operating Handbook (an FAA-approved part of the aircraft). If the latter, then any change to the manual would have to be FAA-approved, and deviation from the manual, including by the owner packing his main parachute, would be unauthorized. Can anyone point to a case where a rigger has been sanctioned (or not) for substituting TSOd or other parts from another manufacturer? Mark

AC 105-2C for the rigger's privilege of combining compatible components. Terry quoted the relevant portions earlier in this thread. Parachute Rigger Handbook has TSO performance specs in one of the appendices. An on-line version of the PRH is at http://www.pilotoutlook.com/pilot_training/parachute_rigger_menu. Mark

Including free bags and pilot chutes with rigs is common practice, although not required by regulation. As an analogy, for years main canopy manufacturers shipped them on risers and with deployment bags; harness/container manufacturers supplied risers and d-bags only for an extra charge. TSO-C23c and C23d call out seven major components, starting with the pilot chute and ending with the ripcord. "Best practice" (a legal term of art) would be to follow Shlomo's advice and use only manufacturer-supplied replacement parts, but it is not settled that riggers are limited to substituting only canopies and not other components. Mark

If the student pulls on the tandems, would that count as the PRCP? No. BSR E.5.b requires a "solo exit and practice deployment with stability in the IAD or static line program prior to advancing to freefall." Mark

That's the way I read the cross-over training requirements. Cheers, Mark

It isn't written in the BSRs. The skill progression in the ISP is recommended, not required. The IRM says Coaches may make linked exits with students cleared for group freefall, but does not prohibit Coaches from making linked exits before that (in a SL/IAD progression, at least). I don't know whether the BOD considers IRM limits to be mandatory (like BSRs) or recommended (like ISP). A Coach may supervise instability drills in a SL/IAD progression program (BSR E.4.a.(4)). That makes it easy, then. Once a dz has decided to deliberately ignore one of the BSRs, you may as well ignore the rest of them, too -- they may as well use whatever instructors they want and make it up as they go along. Sigh. The whole controversy seems so pointless, so easily avoidable by just sticking a PRCP in between the tandems and the clear-and-pull. I think I know the dz you refer to, and I am disappointed to hear what my friends there are doing. Mark

The progression from tandem to clear-and-pull (without an intervening PRCP) is not authorized by BSR. If that is the program in use, it is in violation of the BSRs. If there is a PRCP before the successful clear-and-pull, then the student may progress to freefall in a SL/IAD program, supervised by a Coach or Instructor. (Since a Coach rating is a prerequisite for an Instructor rating, it doesn't matter whether the Instructor is rated for SL, IAD, AFF, or Tandem.) Since the BSRs do not require SL progression students to do some number of 5, 10, 20, or 30 second delays, a student has been cleared for freefall may go to 10,000 or 13,000 like everybody else. Maybe not wise, but permitted by the BSRs. Then the issue becomes whether a Coach or SL/IAD or Tandem Instructor may do a linked exit or dock with a student. The ISP may suggest "no," but the ISP is not controlling. As long as the DZO is careful to describe the program as a variation of SL/IAD progression, I think it is possible to within the BSRs. Again, that assumes there is a PRCP before the clear-and-pull -- and please do not make the assumption that I think such a program is prudent. Mark Mark

Now I'm wondering what that packs like. Larger. I dug and dug thinking there was a post that reprinted tests done for a Skydiving Magazine Article. The pack volume for the smallest optimum was the same or larger than a PDR of the same size. I think it might have to do with the quantity of reinforcement being increased... Now, once you got to the 143, it was much smaller. So, for the small ones - buy them because you like the flight performance. For the bigger ones, save some volume... Now without the data, I have no proof... Anyone keep back issues of Skydiving Magazine???? There were two articles in October 2007 Skydiving, one by Sandy Reid, one by me. The table in Sandy's article does not have a volume comparison for Optimum-99 and PDR-99, possibly because he has not done a volume measurement for the PDR-99. Optimum-106: 258 cu in PDR-106: 253 cu in Optimum-113: 263 cu in PDR-113: 286 cu in Optimum-126: 286 cu in PDR-126: 296 cu in Optimum-143: 327 cu in PDR-143: 356 cu in Remember these are numbers from individual canopies, and there is some variation even within canopies that are intended to be identical. My experience has been that the Optimum reserves pack about 1 size smaller, including the smaller Optimums, so my experience doesn't match Sandy's measurements. I think the larger pack volume Sandy found with the Optimum-113 is more measurement error than anything else. The amount of reinforcing tape in both models is about the same; line volume, slider grommets, etc. would be nearly the same for both models, so difference in pack volume should show up most for canopies with more fabric. Mark

If the pressure bump was not recorded at the actual time it occurred, if the time was backwards estimated based on recollections, he may also have jumped earlier or later. Mark

Small correction: The description was of two pilot emergency back-type (not main) parachutes, and two chest-type reserves. "Main parachute" is a term used for the primary parachute in an intentional parachute jump. A parachute system use for an intentional jump would have a main parachute and also a reserve or auxiliary parachute. Because he did not ask for two mains and two reserves, what he got was four reserves, two of which were usable (the back types). Neither of the chest types was usable as a parachute, one because it was a dummy, the other because there was no way to attach it to a harness. Mark