TomAiello

I've found that pulleys are very useful in reducing wear on the rope. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

DJ Higgins once packed in the back seat of a car, with the windows down, on Interstate 84 between Boise and Twin Falls. I've got the video of him jumping that pack job somewhere (I think it's also on SM.com). -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

There is not really any other reason to be at that exit point. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

MDV is an acronym for Mono Directional Valve, so no forgiveness is necessary. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

I'm not sure. I think you've captured the essence of it, but I also think that the "gust induced stall" phenomenon that Pete referenced is pretty relevant. Once the wing takes shape as an airfoil it could still be experiencing a gust induced stall. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

Sure. As long as you understand what you're doing, then whatever you want to do is what makes sense. In terms of getting used to the canopy, there's not a whole lot of difference (some in steep approaches, I think, but overall very little) between a vented and unvented canopy of the same model. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

If god had meant for babies to be hanging off of women's breasts in public, he'd have made milk come out of those breasts! -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

Sport jumping is neither? -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

Thats what rigs are for silly man Jumping with a rack kind of sucks. Landing with an ice axe is downright dangerous. Jumping with a haul bag? Never tried it, but I can't imagine it would work out too well. I once had a friend of mine watch me jump and then hike off with all the gear. And it was a longish hike. Funny thing is that he was a ranger, and we were in a national park. Hey j_ung, you've got to try rappelling off the end of a rope. BASE gear helps make it survivable, but it's pretty much the ultimate cognitive dissonance moment, if you are a climber. I bet you could set it up as a launch for a rope jump, too, if you didn't want to hassle with the parachute. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

You should have stopped by the Holiday Inn and said "hi". Preferably before the fatality, because after that I was pretty much busy and bummed for the rest of my time in WV. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

What is this "coin" of which you speak? -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

Thanks. I went back and fixed it. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

They could be, but I don't think you could say for certain. To check if brake settings are too deep, grab a riser and initiate a turn immediately after opening (with the brakes set). If the canopy turns, the brakes are either too shallow or just right. If the canopy stalls straight down without turning, the brakes are too deep. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

That one. Some of my canopies have as many as 4 brake settings which I'll use in different situations. It can be tough to predict conditions while packing, though, so it's something of a crapshoot. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

Standard Disclaimer: The following are [I]my opinions only[/I]. Ask lots of different people, read everything you can, and then decide for yourself what you think. A modern ram air canopy has two functions, which it performs in sequence. First, it acts as an aerodynamic decelerator (a big air brake) to stop the jumper's fall. In this it performs the same function as a round parachute (this is pretty much the only function of a round parachute, although drive vents complicate things a little). Second, it acts as a wing. Once it has finished decelerating the jumper, it transitions into an airfoil, which flies the jumper to the landing area, and allows a nice flared (and soft) landing. For purposes of this discussion, the interesting stuff all happens during the transition from the first point to the second--while the parachute is changing from a pure aerodynamic decelerator into a flying wing. Unvented Slider Down: First lets talk about the opening sequence of an unvented slider down canopy. I'll start at line stretch (because that's where the difference between vented and unvented starts to matter). Bottom Skin Expansion: After the canopy reaches line stretch, air hits the bottom skin and causes it to expand. [The tailgate promotes a nose first expansion, but let's leave that aside for now, because it's going to work in a roughly similar fashion on vented and unvented canopies.] The bottom skin expands until it's roughly rectangular (something approximately the shape it will be once the canopy is inflated). Cell Inflation: After the bottom skin expands, the cells fill with air. This happens for many reasons, but a prime motivator is that the canopy will slide or hop forward (almost in the same fashion as an old style tracking jumper--by deflecting air off the bottom skin). This forward motion is not strictly "flight" (the cells are not yet inflated and the canopy is not yet formed into an airfoil shape), but rather more "deflection." This motion results in air rushing in through the nose of the canopy, pressurizing the cells (and creating the "wing" that you will fly to the landing area). Flight: The now inflated wing begins to fly. Vented Slider Down: So, what do the vents do? Basically, they synchronize[/I] the Bottom Skin Expansion with the Cell Inflation, so the process looks more like this: Bottom Skin Expansion and Cell Inflation: As the bottom skin expands, air passes through the vents and pressurizes the cells almost simultaneously. The canopy moves directly into the "flight" stage without needing to "hop" or "slide" forward to pressurize the cells. Flight: The now inflated wing begins to fly. Slider up: Interestingly, the slider works in a different fashion, to the same end. The slider also synchronizes bottom skin expansion with cell inflation. However, instead of accelerating the cell inflation to match the bottom skin expansion, it operates more by slowing the bottom skin expansion down to the rate of cell inflation. So, with a slider, the process looks like this: Bottom Skin Expansion and Cell Inflation: As the bottom skin begins to expand, air rushes into the cells. The slider slows the bottom skin expansion such that the cell inflation is almost synchronized with the bottom skin expansion. Flight: The now inflated wing begins to fly. It's been my observation that the slider basically overrides the vents (or they work together, if you prefer) such that there is virtually no difference between vented and unvented cell inflation slider up. So, what about the brakes? With properly set deep brakes, the canopy should transition into a wing with the minimum possible forward speed. Some forward speed is necessary for the wing to fly (otherwise it's stalled, and it will drop the jumper out of the sky very quickly). The goal of setting your deep brakes (which ought to be done custom to your body weight) is to find the ideal point where the wing has the absolute minimum forward speed to still function as a wing (flying forward) and to be controlled (respond to riser input). [If you are a "toggles first" kind of jumper, you can pretty much ignore that second part, because you'll give the canopy more forward speed by popping the brakes, pulling it back off the stall point as you initiate your turn.] What happens if your brakes are too deep (on an unvented canopy slider down)? If they are way too deep, you'll find the wing opens in a stall, and never gets flying. The canopy will simply drop out of the sky until you pop the toggles. This may be because the pulled down tail (from the brakes) is essentially counteracting the forward "slide" necessary to inflate the cells, and the cells are never inflating. It might also be because the cells do inflate, but the resulting wing never begins to fly, and instead stalls and drops (or slides backward). For ease of reference, let's refer to this phenomenon (stall during initial inflation, or failure to inflate at all, followed by backsliding or straight dropping) as Deployment Stall. What happens if your brakes are too deep (on a vented canopy slider down)? This is where you can see opening backsurge start to develop. As the air rushes in through the bottom skin vents, it surges upward, strikes the topskin of the canopy (inside the cells) and then is deflected (both forward and backward). Some of the deflected air is expelled through the nose of the canopy, pushing it backward. This creates a noticeable backward movement of the canopy. I've seen this backward movement stop (and the canopy stabilize in a nearly parked flight mode, sinking almost straight down), and I've also seen it turn into a full on stall (with the canopy losing altitude fast until the jumper pops the toggles and the canopy recovers by diving forward to gain speed). What does the wind do? In general, during the transition phase when the canopy is changing from its aerodynamic decelerator mode to its flying wing mode, it is still susceptible to wind effects. However, the effects of the wind on this transition may seem counter intuitive. Tailwind: As the canopy starts to transition, the tailwind essentially blows wind up the canopy from tail to nose. The canopy "perceives" this wind (in combination with the inflation forces) as "slowing" the rate at which the wind blows into the nose (or if you prefer, the rate at which the canopy moves forward). This means that the back surge air (the air that is flowing in through the vents and striking the topskin) is "stronger" by comparison, and hence more likely to cause a backsurge. The tailwind effectively deepens the brake setting during this step, and also results in a slightly slower inflation (i.e. a greater time from PC pitch to flying wing overhead). Headwind: During the transition phase, a headwind pretty much acts in the opposite way of a tailwind. The canopy "perceives" the headwind as increasing the force into the nose, and hence reducing backsurge (and effectively making the brakes more shallow for this step). The headwind effectively makes the brakes shallower, and also results in slightly faster inflation (i.e. less time from PC pitch to flying wing overhead). In general, I'd say that the vents aren't [I]necessary[/I] for a beginner, because the vents are most noticeable on lowish slider down, and especially underhung (where you want the wing flying to avoid the object coming out below you), solid objects. Beginners shouldn't really be jumping those types of objects, so why waste the money buying a (pricey) bit of technology that won't help you on the objects you are jumping? I think it's better to wait and get them on your next canopy, which you're more likely to be taking to such sites. No. Faster cell pressurization does not automatically yield more forward speed at opening. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

Slider up or down? Any wind? Freefall or static line? Deep or shallow brakes? Were the brakes customized to each jumpers body weight? Are the canopies the same size? Are all the canopies you are comparing the same kind (i.e. all FOXes)? -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

Yes, but it's pretty condition dependent. A "good" brake setting in zero winds can result in backsurge in significant tailwind. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

In my experience backsurge is much more common in tailwinds. Check out the video of (I believe it's Liv) jumping the fire lookout on the ABA 2003 (? might be 2004) video and you can see what I mean--the canopy backsurges hard enough to strike the tower tailfirst and hang up on it. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

I think River has a lot of the best lines, because her dialogue is so random that Joss Whedon could throw in his commentary through her. I also liked "Mal...bad....in the Latin..." -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

Functionally, unless it's really, really dirty, I don't think you need to clean it. With mud, I've had the best luck just letting it dry and then shaking it off (it's just dust, then). If it's something that's sticky (so that the mesh sticks to itself), it could cause some hesitations. If that's the case, I'd consider just ditching the whole PC. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

Hmmm. I'd have to say the one in my sig line. edit to add: audio file here. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

I used the structural beams of the basement I was packing in. They were totally immobile, so I could tension around them very hard without any issues. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

Have you tried wrapping them around something tightly? I've used beams before, and made a couple 90 degree bends in the lines. It's not ideal, but it did work. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

What style of toggles where you using? -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com

Was legal. Started getting periodic closures when we (jumpers) did dumb-ass stuff (like jumping during a funeral in the village below). Now closure seems like the normal state of affairs on that one, but don't take that as "it's illegal, so why not" because there are many other exits in the same valley, governed by the same folks, so we still have lots to lose there. -- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com