hackish

I subscribe to a mag called Nuts and Volts. This month they had an article on how to reef a parachute for a model rocket. They tied the hem shut with a piece of spectra and built a circuit to cut it with a piece of nicrome wire at a pre-set altitude. They defined reefing as choking it off at high altitudes for a gradual deceleration so they could fully open at a lower altitude. I'm not so confident about their definition as I've always felt that reefing referred to the opening. I also think their task would be better suited to a drogue... However, I was wondering how the older rounds were typically reefed from a terminal deployment and what sort of system worked the best? -Michael

Crashing the ground with even high speed and or high speed stall.... I never really gave it much number crunching but my canopy feels like it recovery quicker on rears than brakes. Not like a sabre2 has a long recovery arc anyway. What canopy would you need to have the strength to go directly from a dive to a stall on rears? -Michael

I know I'm at a small DZ, but none of the 2000-3000 jump old guys who have been doing it for 30 years ever used a calculator. They do as I was taught, look at the uppers and have a discussion about where the spot should be. When I look at some of the stuff recent business graduates are doing to figure out costing I get dizzy. I look at a gizmo and say I've got to sell it for $500. They go and churn numbers for an afternoon and come back to say "you need to sell it for between $486.33 and $515.92" Maybe our weather makes it easy? Is it really a problem? Is this exercise looking for a solution without a problem? In business and spotting you hone the skill with a series of near-misses, hits and major fuckups. Not many walks back to the LZ last year at my DZ. -Michael But, let's not forget, the older experienced businessman once had to do the formulas on paper, before his experience allowed him to do them in his head. Several former Jumpmasters and Pathfinders in this thread... we started out doing the the formulas on paper long before we had the experience or confidence to do them in our head.

There are hundreds and hundreds of AAD threads in the history. I firmly believe that all the major AAD's on the market will operate correctly or more technically within their parameters. I bought a Vigil II. After 12 years, unlike your cypres I can still jump my vigil II. -Michael

I'm going to write an article on my findings, but if you look at a pin you will see that the pin part has been worked into it's pin shape. In fact you can even see a slight taper on the pin shaft itself from where it was worked into that nice round shape. Next, look at the swaged part. You can see where it was "smashed" by repeated blows to deform the metal so it flows into the cable forming the swage. These areas, are confirmed to be much harder than the area in front of the swage where the metal was worked less. Although I didn't anneal a pin completely to see how much this area was work hardened, there are 3 different areas of hardness in the pin. -Michael

What would the result be of going for the rears instead of the toggles on a canopy like that when he realized he was in trouble? -Michael

A lot of the older jumpers grumble about the light watchers on a load... well back in my day we.... This really depends on what sort of DZ you're at. At a small cessna dropzone you must have and use your spotting skills. Some of our pilots are good at putting us up the right place but others are good only at getting us to 10,500. At the larger DZ's on the larger planes I can understand how the skill of spotting is lost, but many of us still know how and regularly practice spotting. I snicker to myself reading the ideas here. It's like a business student running fomulas versus an old businessman who just knows from experience what to sell a product for. The engineering types can build a complex system that's difficult to use and accomplishes pretty much the same thing as an experienced spotter. -Michael

A rigger can only do the best they can do. For some that means continuing to study and practise. The rigging ticket is like an "A" license. The advice given by every "licensed" skydiver isn't always good nor is the advice of just any rigger. I will continue to play with these pins and post the findings with hopes it will help the general rigging knowledge in the community. -Michael

Sorry Cari, don't have access to anything past 2004 in that journal. Hopefully what pchapman posted will suffice. -Michael

If you want pm me your email and my better half can get it from school. -Michael

If you design and construct an idiot-proof spotting calculator then someone will just invent a better idiot. I doubt the consistency of even a well designed spotting calculator would improve upon that of an experienced spotter. -Michael

The reserve requires the lines to be pulled from the freebag before any stress is placed on the locking stow. If it breaks at that point it has already done it's job. On my Vector3 main bag you would need probably 3 of 4 elastics to fail before it could debag itself. Considering all the lines are stowed on elastics there is a very good chance you already got a properly staged deployment at that point anyway. The point I'm trying to make here is that the elastics are there for a very good reason - to stage the opening. I fail to understand how removing them replaces their function. -Michael

Ok, Jerry owes a stale doughnut or a dollar... or something like that. Just got back from the machine shop. The swaging and the round part of the pin were significantly work hardened. Swaging came in at about 60 and the pin around 50 while the unswaged and unformed part of the pin which may or may not be slightly work hardened came in at 10. I will do some additional testing to determine the amount of force required to yield the pin itself. This will translate to how many pounds of closing force you can apply before bending the pin. -Michael

My tuck tabs always pop out. More than once people have brought this to my attention and normally they offer to fix it then do. I don't mind. If a handle pops out and someone grabs the MLW to bring it to my attention fine. If a handle has popped out I should be doing a better job of watching my own shite. -Michael

I think it depends on the sport. Take sport shooting for example. If you did anything against the rules like pointing a firearm, unloaded and bolt out or not your ass would be forcefully removed very quickly. You'd probably also be banned from the range until you were cleared and probably forced to retake the safety course. More than once in auto racing I've seen people kicked off the track for doing stupid things. Show up to race drunk and a very dim view would be taken of that too. -Michael

I've seen more analogs fail than digitals. For the most part I think the failure mode on a digital should be a blank screen so you can revert to the 2 alti's in your head. I had an analog fail on me. Stuck at 5,000. Was still at 5000 when I landed... -Michael

I tried a surgical tube first with some model shop rubber cement it stuck but not very well. Next I tried some old RC model airplane fuel line - that was silicone but I couldn't find any glue for it so I tried the rubber cement but it didn't stick at all. When I considered the time and the costs of the materials I found that expensive as they are the reason tube stows are expensive is that they're difficult and expensive to make... Next time I'm bored maybe I will see about making a tube stow machine. Somewhat easier than a 150hp snowblower - also on my projects list. -Michael

Very interesting. I tried more than once to make them without success. Couldn't get glue that worked well enough. -Michael

Reserves also stow the lines in a pocket. While I don't know anything about BASE rigs I did watch some oh so carefully being packed once. On a reserve freebag the pocket is setup to be emptied first and the lines must then pull themselves from 2 stows before the canopy is allowed to exit. The same sort of principle has worked for years even back into round deployment diapers. My concern here is that I see nothing to stop a good hard snatch from the PC from extracting the lines and canopy from the bag all at the same time. -Michael

From a technical point of view I'm not that confident with the design. The lazy bag does not do anything to try and guarantee that the opening is staged correctly. If the bag closing tabs end up being tugged out before you reach linestretch it could definitely contribute to a mal. -Michael

I'd rather recognise it as something that's easy to do and triple check it every time than to try and convince myself that I'm such a careful person that I'm immune to making said error. -Michael

If 20 years ago sparky dispatched dummies and saw 10% of them go splat. Then 20 years of active work in the industry and knowledge and experience of modern equipment pass and he's still solidly against it then I don't know how relevant a "that was then this is now" comment can really be. It has been some time since I read over the redbull proposal but I seem to remember that they'd already taken into account not being over spectators. I would just worry what a stunt like that would do to the next 10 years of skydiving if it did go bad. -Michael

Thanks for the offer Jerry, someone is going to send me a couple of pins and I'll see if I can fit them in the rockwell tester. Some are newer and some are older so it will also be interesting to see if there is a difference between them. Maybe I will take one and anneal it then compare the standard pin test on both. Sadly there is probably already someone in the parachute industry who has studied all this stuff and already knows the answers. As for work hardening, it is my understanding that the amount of hardening is related to the amount of plastic deformation. In other words, shotpeen something and it will be surface hardened but swage it or form it and you'll harden it all the way through since you're deforming the entire piece, not just the surface. Also, it is not possible to heat treat austenitic stainless for hardness. For work hardening while drilling, yes but it's more dependant on selecting the proper feed rate since you need to ensure you're taking a thick enough "chip" out. More than once I've had to anneal a hole with a TIG torch and try to avoid pulling the chromium out. Torch in one hand, water in the other :) I've even found that water cutting seems to harden 304 up pretty badly. I'll post it up for all to read when I get to testing these pins. -Michael

Our last day of the year it was -14C at 6k and damn-it I didn't want to go any higher than that. Subject to instructor approval, I've found that mechanix gloves do a good job of keeping my fingers warm and still giving good feeling for grabbing the pud. Also, if you have a turtleneck it's not a bad idea. Jackets can be fine but don't use one with a collar because it will slap your neck the whole way down. Or as others suggested wait until it's warmer. Other things to think about and talk with your instructors about is that fact that bulky clothing can cause your handles to be in places you're not used to. PS you floridians are wimps... -Michael

Haha, My first internet date was a chick where the first thing she said to me was "you'll do, want to go back to my place and f*ck?" Second was one who looked nothing like her attractive photo and she admitted it was of her roommate. Her defense - well everyone says we look exactly alike. I can assure you they looked nothing alike... Lots of trash online but still some good ones. I think it just takes persistence. I'd pretty much given up after about 20 dates in as many weeks. Wasn't finding chemistry. Em actually found me and the first time I met her I knew she was the one. -Michael