mark

After doing the calculations, I find that the average G-force in a skydive is 1.0 even if no parachute is used. That's the same G-force as just standing on the ground. Why bother with all that nylon? Mark

I like the X-mod on my X-FX99 and X-VX93. Peformance issues aside, my HMA lines last longer than Vectran. And when I re-line my canopies, I won't need a rigger to fingertrap or bartack anything -- all the lines are larks-headed at the attachment points. In exchange for a little more $ up front, I save a lot later on. Mark

MRVS is located between Henrietta and Lexington, Missouri; about two or three miles to either. Skydive Kansas City is in Butler, Missouri. Not in Kansas. The average wind speed in that area is about 20% greater than Florida (excluding Key West). According to data provided by the city of Henrietta, the average wind speed is greater than 10 mph (exceeding the BSR limit for students equipped with round reserves) 8 of 12 months in the year. Consider also that winds at night are generally lower than during daytime. Every airport has some obstacles around it, such as airplanes, cars, hangers, electrical lines, roads, fences, ditches, etc. MVRS is in the Missouri River valley, close enough to the river to have been flooded in 1993. Obstacles which a square-equipped jumper doesn't think twice about can be hazards to someone jumping a round. I've used a round reserve in Kansas. It wasn't much fun, and I don't think I'd have enjoyed it any more if I'd used it in Missouri. Mark

So I checked the USPA dz directory, and found links to Skydive Kansas City in Butler ("perfect safety record") and MRVS ("more experience"). Hmmm. Is not all peace and love in the KC area? I think you're seeing "It's a feature, not a bug!" If I had to guess, I'd say that MRVS is in the process of converting to all square reserves, but isn't there yet. Their website says their freefall rigs have square reserves. It may be true that in a two-out situation, round & square is better than square & square. However, most student malfunctions are of the single-canopy variety: didn't like the first canopy, gonna get rid of it and try a different one. If you have an emergency and need to use your round reserve, you still have an emergency. Square reserve canopy control is similar to square main canopy control, so no new techniques to learn under stress. Square reserves give a greater choice of landing areas. Square reserves allow landing going forward in most wind conditions students are likely to jump in. With a round reserve, you are likely to land going backward (unless you land downwind, which is not an improvement). Round reserve landings should be done with a PLF; I haven't seen many civilian instructors capable of doing PLFs, let alone teaching them. Bottom line: in the most likely scenarios, a square is much better than a round. Rounds are inexpensive -- I can't get any takers at $200 for an airworthy round reserve. And rounds don't have freebags, so there's less to lose if a student has a cutaway. Mark

That's three things. The reinforcing was just at the line attachment points. Mark

I think you may have misread the description. The fabric itself comes as a composite panel formed by fused layers. The pieces for a parachute canopy (or sail, or other application) have to be cut out of the fabric panel, and can then be sewn together or fused/glued along the seams. For sport parachutes, sewing is better: sewing puts holes in the fabric, which allows air to escape while packing. Atair Dan's parachute is sewn. Mark

How many Cypres-equipped students have died because their AADs failed to work as advertised? None. How many Instructors have died because they chased their students to Cypres-firing altitudes? At least one. Did the dead Instructor improve his student's chances? No. He made them worse. Instead of his student having just one canopy out, the student had two out. The Instructor's heart was in the right place, but he wasn't thinking clearly, and by his actions he endangered his student more. In three cases I know of, Instructors caused a more dangerous situation by accompanying their students to Cypres-firing altitude. I don't know of any cases where things got better because an Instructor was down there. There is a small chance a Cypres might fail to fire. There is a large chance the pursuing Instructor will make things worse instead of better. Which chance would you prefer? Mark

I didn't know Chachi had a blog, and I still haven't read it. I did get to jump with him on his first jump, on the main side. Great fun, wacky sense of humor; I liked his banter with the manifest staff (they liked it, too). He was really pumped when he landed after hs jump. I don't presume to speak for John or Kerry, but I look forward to jumping with him again. And I think any dropzone should be glad to have a jumper with his enthusiasm and gregarious personality. Mark

Was my peeve, too, until I looked at aircraft logbooks. Those logbooks have neat rows and columns for filling in information for different services, but mechanics merrily ignore the rows and columns, use big rubber stamps instead, and the FAA doesn't mind as long as the information is there. Now I ignore the vertical lines and column headings. Not enough room for a Cypres serial number? No problem: borrow some space from the column to the left or right. My new peeve is folks who think they can't use more than one line of the data card per repack. Hey, if it doesn't fit on one line, use the next one too. Oh, yeah. My other peeve: where except on parachute data cards do you sign first, and put details last? Would you sign any other legal document that way? Try this instead: date first (manifest likes that), details next (maybe just i&R, but if you did the PD 30# test, patched the reserve, and installed a CW-0301 Test #1 compliant ripcord, just use as much space as you need), then location/rigger #/seal, and finish with your signature. Mark

From an e-mail conversation with Kim last year, this has to do with the data logging function rather than any danger of firing. A Cypres doesn't have any published data logging functions. Mark

When I bought my first Wonderhog, Bill Booth recommened 3-ring maintenance every 30 days, more often in dusty or dirty environments. Things change. The latest version of the Vector 3 manual recommends maintenance every 3 months. Mark.

Atair Dan has a personal parachute made from Cuben fabric. It is sewn (with E-thread, I think), but he siad it could be glued together. For sport parachutes, sewing is better because it allows more or less normal packing. The fabric is zero porosity, unlike ZP which allows some air through the weave. Dan's canopy was reinforced at the line attachments; I don't recall if the reinforcement was just another layer or two of Cuben, or some more conventional fabric or tape. The existence of Dan's sport parachute doesn't mean Atair has a good solution to the additional stress caused by no-stretch fabric. Some combination of slider size and shape, pilot chute size, and freefall speed obviously made the openings acceptable for him, though. Dan said the fabric was quite expensive, so don't look for sport applications any time soon. I got the impression his parachute was more of an engineering experiment than any sort of pre-production model. Mark

Old news. http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=1471202 Mark

http://www.jumpshack.com/Read/Tech/canopy_volume_chart.htm Doesn't list SAC, though. I was surprised to see the difference between a Phantom 22 and a National 22. My guess would be closer to the Phantom, but since you'll be getting a freebag and pilot chute from Jump Shack anyway, why not call Nancy or John? Does your Racer have short reserve risers or standard? The short risers are just long enough to have the connector links inside the pack tray; standard risers would go all the way to the lower corners of the tray. I've refused to pack a couple rigs with squares installed on short risers: the control line guide ring winds up between shoulder- and ear-level, which allows a flare only to half-brakes. Mark

Sorry, not a good analogy. Pushing a kid out of the way even if he or she is already running is making his or her situation better. Chasing your kid at Cypres-firing altitude is making his or her situation worse. Wanting me to be the instructor endangering your daughter's life instead of endangering it yourself strikes me as no improvement. Mark

I do not know the specifics of this situation. More generally, though, there is a gap between what is legal and what is prudent. Prudent would be a knowledgeable person on the ground, manning a radio link to the aircraft, and manning either the primary or back-up radio link to receiver-equipped students under canopy. Legally, though, there is no FAR or BSR requirement for dz radio communication with the aircraft. The dz ground-to-air communication to the aircraft may be panels or smoke. If the FCC didn't mind, it could be cell phone. The person manning the ground-to-air communication does not need to have any ratings, and could be a whuffo, spouse or student. The FAA requirement is for contact with ATC. And there is no FAR or BSR requirement for student radios. Mark

Okay, let's try this again. The chances of good things happening because you chase a student below 2000 feet are slim. The chances of bad things happening are large. If you chase a tumbling student, you are likely to be above them. If you chase them at Cypres-firing altitude, your freefall-canopy collision will result in serious injury or death. If you misjudge your approach and are under your student when your Cypres fires, same result. If you are next to a Cypres-equipped student when your Cypres fires, your reserve canopies will deploy next to each other. If you are successful in deploying someone's main parachute at Cypres-firing altitude, you make his or her situation worse instead of better. Now that someone will have two parachutes out. Those two parachutes may or may not entangle with your Cypres-deployed reserve. If you didn't have the skill you needed above 3500 feet, how will you suddenly develop the skill below 2000? Why would you want to endanger your daughter's life by chasing her down to Cypres-firing altitude? Mark

PD Sabre 120 DOM 4/97 has a stiletto serial number, ST120-R00017. (Don't know where the "R" came from -- must be a typo in my records!) PISA Tempo 170 160080 DOM 5/96 has a data panel that misidentifies it as a 150. Stuff happens; there is noise in even the best qc system. Mark

Three recent incidents like this resulted in a two-out situation for the student. In each case, the instructor's heart was in the right place, but his actions made the student's situation worse, not better. The good news: the students survived in spite of their instructors. Mark

Unfortunately, it is possible to snag the tail of a Caravan. www.atsb.gov.au/aviation/pdf/vh-mmv.pdf Plan A (Avoid) seems like the best option. Mark

I've never seen a bird while I've been in freefall, but I have seen red-tail hawks in the same thermal I was soaring in at five or six thousand feet. I don't think they hunt from that altitude -- I'd rather believe they were there for the same reason I was: enjoying effortless, solar-powered flight. Mark

Paralog is not as universally compatible as you suggest. I haven't been able to make Neptune/Mac OS 10.4/Paralog work, and, to the best of my knowledge, neither has Klaus. I'd like to hear from someone who is successful with ProTrack/Mac OS 10.4/Paralog. I'm skeptical, because the RS232-USB adapter makers claim compatibility only with "OS 8.6 and above" which I'm not convinced includes OS 10. Mark

This thread is on its way to the Bonfire. While we wait for that, we can agree this story is a pleasant piece of fiction, written by someone who has only imagined he's made a jump. I leave it to other posters to point out the many amusing departures from reality. Mark

I'm sure you'll get quite a few replies offering both rounds and squares. Before you accept any, please consider how flammable nylon is. I'd discourage you from using parachute fabric near any heat source, including stage lighting. Best of luck. If you think you can display parachutes safely, PM me about what I might have in the attic. Mark

Except Wings. Mark