pchapman

Is the reserve freebag more "conventional", or does it still have the bungees, tubular plastic chokers and all that? (It has been a long time since I last saw a Strong tandem reserve.)

A big rig sticking out at the sides or pushed off your back will be a bit destabilizing but it isn't a big factor, even if it makes you work harder trying to arch nicely. How you position your body is what will determine your freefall. Having a smaller, better fitting rig later on will make maneuvering easier, but the rig is secondary in effect. Although you may be shorter than many, plenty of people have had to deal with big, heavy, uncomfortable student rigs over the years. The more common problem for a smaller student and big rig is it being too loose on opening, with the chest strap riding up to one's neck. So one has to do the best one can in getting the rig snugly fitted. I haven't worked with a ton of students so this isn't an expert opinion.

The German document in this thread that has a name like "4 - Gehoerschutz fuer Fallschirmsportler" does mention that the custom earplugs do have a channel to equalize pressures, as do some of the fancier non-disposable earplugs. The author doesn't recommend the yellow EAR ones, or other tapered closed foam earplugs for freefall due to lack of same. But I've never had a real problem when keeping the EAR ones in during freefall. Bigger ear canals perhaps. I find some of the more conical ear plugs don't seal very well at all unless jammed in tight. And I avoid the really cheap, very squishy conical ones provided free at the Montreal tunnel -- way too easy to have those not seal and work their way out, and find yourself with a ringing ear after a tunnel session. It's all a bit messy what is happening in freefall, trying to balance both the inner ear pressure (through the Eustachian tube), and the outer ear pressure (past any ear plug).

Thanks for finding the thread, Pat, after 6 years! I would need examples to see how it worked according to your scenario. For example, one might say jumpers open at around 2500', and on one set of freefall tables (not necessarily what one used in those days), a 15 second delay is 2005'. So jump at 4500'. But would one have used 2500', not 2000' as an assumed pull altitude? And a 30 second delay shows up as 4615', so then one would pick 2500' + about 4500' = 7000'. So it all depends on what assumptions one uses. Perhaps a particular set of them make it work out the way you say?

I did LOL at the bit where Hitler has his fists up and the subtitles are about him risering out of swoops. That was well designed.

While I don't know for sure, I thought the highlighted part was to cover those outside the USA -- to try to get some sort of medical even if they couldn't realistically enforce the same standards as in the USA.

It's one thing to control a tiny BD-5 with a side stick, or some very light aircraft, but it must get tougher to get the control forces right on something bigger like a Cirrus. Not much leverage arm on a side stick. The Zenith line of homebuilts, many have had a center stick to keep the control system really simple, with a Y-grip to allow both pilots to use it. Other homebuilts have had a center stick without the Y.

Aw, cut them some slack. They were approximately right. But yes it is all arbitrary. A lot of standards have been re-defined. So the metre (as you probably know) is no longer based on the length of a bar of platinum in a vault in Paris (or something like that), but on the distance light travels in a vacuum in a particular fraction of a second. Light speed in a vacuum seems to be a pretty universal constant, but then the unit of a second is somewhat, even if it is a convenient fraction of an approximate earth day. I just don't want to give "arbitrary" a bad name. Whether we drive on the right or left side of the road is also arbitrary (even if based on various historical reasons), but we had better pick one or the other!

I always wondered why so many Americans keep saying "centigrade". Someone must keep teaching that term?? The scale was renamed "Celsius", in 1948 -- so it isn't like a change that just happened.

On behalf of the possibly silent majority who are reading but staying out of the fight, keep the interesting debate going, but remember that if there's an enemy, it's the FAA, and not each other!

I guess the same could be said about the Parachute Rigger Handbook.

I'll guess it is largely a matter of time. A bail out at 40k' will leave a lot more time to start spinning up than if bailing out at 20k'. In cases where pressure suits or partial pressure suits are involved, the additional stiffness of them (when inflated for high altitude bailout) might make it easier for a person with no freefall training to spin. Just as a stiff student is more likely to spin than a relaxed one. Then there's the air density issue. That's a tricky one. When the person gets to terminal velocity, the dynamic pressure felt will be normal (basically pressure = weight), so both the forces leading to spins and the forces available to stop a spin would be like down low, even if the true velocity were a lot more at high altitude. But what they could have been thinking, is that if a tumble of any kind gets going soon ejection, if the speed is well below terminal velocity, and it takes more time to get to that higher speed, then inertial forces are relatively strong compared to aerodynamic ones. That is, it is harder for any natural stability (or crewman's actions) to stop any motion because of the reduced dynamic pressure and control forces available. On the other hand, a lot of ejections from high flying aircraft would be at high speed, whether viewed in terms of true airspeed (eg 500 kts) or indicated airspeed (dynamic pressure, taking into account the lower air density) (eg 220 kts IAS). Either way, the ejection is above the typical terminal velocity for a crewman with a rig on. So in those common cases I'm not sure that the low air density is any issue at all. There can be subtleties that I'm missing though. For example, aircraft wing flutter is affected more by true airspeed than indicated airspeed. Overall I still guess the main issue is the distance fallen by high altitude ejectees, possibly aggravated by stiff inflated pressure suits. When at high altitude, the crewman doesn't just have the option of pulling if starting to spin uncomfortably, due to issues of oxygen, temperature, and large increases in opening shock at low air densities. (In those days they would be talking about ejection seats where the crew wear rigs, and separate from the seat before canopy deployment, rather than having a canopy in the head box. And the seats wouldn't necessarily be drogue stabilized. Some seats might have an automated seat/man separation, some might allow manual seat/man separation. But I don't know exactly what features were on what plane in what year. The key point is, the crewman might be falling much of the way in an unstabilized seat, or with a rig on his back without the seat. Two slightly different scenarios. EDIT: I don't know what body position the military recommended either. I could see that just falling in a relaxed position on one's back would make some sense for those who are not freefall trained. That's particularly true if in a stiff pressure suit)

Had a normal rig, plus a secondary harness underneath (cut from an old rig), with a belly container built for the 3rd canopy to be cut away. The cutaway for that one was an easy to grab loop handle. I got hold of the bottom of one yellow cable first and yanked it out. I was impressed at how fast the 'mal' spun me around, given that the cutaway canopy was 200 sq ft of F-111. It only took a couple seconds of getting whipped around, to think I had proved the point and that it was time to get the hell out of there! Then finished the cutaway, and tried for a minimum time to flip over, stop spinning too much, and dump the main.

No problem, I was just explaining. Every video is new to someone. At 3:09 (The full video on blip.tv)

Hey, I'm in there! Cool. But luckily that wasn't for an accident, but for an intentional cutaway video I posted, where I only chopped one side at first and got spun around. (Only a very brief extract is shown.) A lot of the vids in the compilation are fairly well known -- e.g., a canopy on the Otter tail, Elvis in the parking lot, Cypres fire over a small European town, the BASE jumper sliding down the dam.

Adventure Loft Prestige, introduced 1990, from Texas. Found it in Poynter vol II. ... and just about nowhere else I would imagine. (Who knows, maybe someone from that area would disagree.) Ancient, and I think the company disappeared long ago.

It does look a little messed up, even though PD has some of the most detailed info in the industry. Nothing wrong with you asking, since you have no way of knowing better. Often, "read the manual" is right, but not all the time. It just turns out that in this case it is over analyzing things, if the purpose is to figure out what canopy you should jump. Still, I could see that if you were a drop zone owner about to buy student canopies, it would be a little confusing as the numbers wouldn't match one's own empirical experience. Even though the jump in recommended wing loading going to bigger sizes is rather large, the lower vs. higher loadings can be PARTIALLY explained. Larger canopies are more docile at the same wing loading than smaller ones, so they can load a bit more. Also, there are practical limits to sizes, so for big guys there's a tendency not to supersize their canopy. A smaller drop zone might well have one standard student canopy size for everyone, except perhaps a couple smaller canopies for the really light people, and maybe a couple bigger ones for the big boys. It isn't perfect, but different students will jump at quite a range of different wing loadings.

That post is worth some smilies!

The deceleration distance is a key factor, what with the roof caving in and probably a lot of suspension travel. I ran the numbers roughly: 23 stories might be 230 ft. To make it simpler, say 242 ft which is 4 sec or 77 mph on some freefall tables. (Body position & weight would be different but this is just a rough estimate.) Unless I messed up the high school physics equations, a 50g deceleration from that speed would take 4 ft distance, 100 g takes 2 ft. John Stapp apparently did 45g relatively uninjured in his tests, and I get the impression that survival may be possible to 100g if everything goes right. In any case, "a few feet" of deceleration distance is important for survival.

The peeling only applies to pillow style handles where there's velcro on the handle -- the cutaway handle, or a pillow reserve handle. For a metal D-ring reserve handle, there's no twisting or peeling involved. That just gets pulled. Well, more of a push really - pick some appropriate direction out from the harness and down away from the cable housing. The peeling idea is that it is much easier to separate velcro a bit at a time rather than all at once. Velcro in shear alone is quite strong. Although peeling and punching out are two distinct stages, one should be able to do it pretty much in one continuous motion. (Not a separate "loosen the velcro first" stage.) Hope that helps.

I see that if someone jumps a small, crossbraced, highly loaded canopy, that's 24 points automatically, and there's a minimum of an 8 score in the rest. So the minimum score for such a canopy pilot is 30. So unless everything else is in their favor, that canopy choice will easily put most such jumpers up in the 36+ higher risk category. (Which, arguably, may well be appropriate.)

Hi Popsjuper, I don't so much care what definition is the correct one, but am interested in understanding how mals are defined. I was thinking the sort of situation where the jumper is in freefall with a container open, a bag out, but something snagged, and no canopy open. I'd call that a sort of 'classic horseshoe', even if other situations also could qualify as a horseshoe. The USPA SIM says that a premature container opening can lead to "one type" of horseshoe -- they don't restrict the definition just to that. In general the SIM does use a very wide definition of horseshoe: In another area it is a little more clear that this is supposed to refer to situations other than a misrouted bridle in tow etc, since the container has opened: One could argue to what degree it makes sense to use a term for a specific shape to extend to all entanglements with body or container. For teaching purposes, I can see sticking to the broad definition because it is "in the book", even if the classic form of the mal is sometimes more narrowly defined in practice.

An issue in how to define this incident is that we don't know specifically when the snag happened. Was it "just a mal" and then the riser snagged on the reserve pack tray during the cutaway? Or, more likely, was the mal caused by the riser snagging on the reserve container, before the cutaway? Assuming the latter is true, then the jumper was connected by both the snagged riser, and at the 3 rings. Technically that's 2 points of connection and thus a horseshoe. However, we don't usually use the term horseshoe for that sort of non-freefall situation, also one where there's basically no slack between the two connection points. So it is and isn't a horseshoe. "Entanglement" story perhaps?

Oh, THAT Terry Jones. When I saw the headline I wondered why the Brits suddenly hated Monty Python.

Like Billvon seems to be thinking, that quoted paragraph is hard to interpret. [edit: That's the one in jenn83's post.] It mentions being "airborne", when the manual really means to talk about the Airborne mode. A jumper might well not associate "airborne" with driving to another DZ Saturday night to jump there Sunday. The Vigil doesn't show that it is in Airborne mode, right? Various LED's flash when it hits the 150 ft level and goes into that mode, but that's all I see in the manual. Another confusing item is where it says on p 8 that it will calibrate itself to the current ground elevation pressure. They mention it in a section about turning it on, but aren't clear that this refers only to when turning it on, on the ground -- not what happens if you've moved to a DZ at another elevation with the AAD still on. On other pages, things are more clear. On p22 it says You must only switch the Vigil® ON only once you arrive at the drop zone to get the correct GROUND ZERO REFERENCE. (This statement was worded in a weaker way and not as prominent in the old Vigil 1 manual.) Another useful statement, on p12, is The Vigil® must imperatively be switched ON at ground level of your take-off zone (This becomes the “GROUND ZERO” reference altitude). (That has also been in the Vigil II manual a while, and in a weaker and slightly less clear form in an old 2007 Vigil 1 manual.) Parts of these statements are also seen just after the index in the manual (p4). Every time I look at the manual, I seem to find more. There's something on p21 as well about the Vigil staying on if it doesn't see the original ground zero reference, requiring being turned off and on to get a new reference. I was going to be pretty critical about the manual based on that one quoted section. That part certainly is poorly written, but there are other parts that try to make it clear what a jumper has to do if going to another DZ. It sure isn't a CYPRES, which has a different 14 hour turnoff logic. In any case, boot one's AAD at the start of a jump day at the DZ.