pchapman

Jeez, give Shah a little credit when it comes to the normal use of the English language. He wrote he used front risers and "never got much out of it". It wouldn't have mattered if he wrote "never got squat out of it" or "got nothing out of it". Yes, obviously aerodynamically something has changed, and Shah probably does need a lot more education on canopy flight. (But that's why he started the thread!) In the context of the situation he was in, the small amount of extra forward speed and increased descent rate, for all the effort expended, was indeed pretty useless. If Brian Germain jumped a big Navigator and then said that pulling fronts "really did shit", we'd all nod in agreement because we understood what he really meant in comparison to other canopies experienced jumpers are used to ... even if it wasn't a precise description of the aerodynamic and flight path changes that he might explain in a classroom, that could be useful and significant in some very specific situations, but of little use in many others.

Fair enough, but at least that's not uncommon for tandems in general. At C-182 DZ's it is very common for tandem students to put feet on the step, so during the exit they are knees to chest. No big deal, that's just the way it is without a huge clear doorway. Or even for Caravans, exits can be squatting in the doorway. So there are plenty of ways to exit that are "scrunched up", where a little effort is needed by the student to actually extend their body & arch.

Man, that's boring, just a reversed 3 ring, that was used a lot by Parachutes de France, and was seen in in the early 1990s in North America too. Someone else can explain the advantages and disadvantages. The system is basically not used any more in North America. Not sure about Europe.0 When you mentioned "Russian" and I saw old gear with a KAP-3 / PPK at the start of the video, I figured you would mean the upside down 3 ring system. After the 3 ring system came out, the Russians created their own version of the 3 ring that was just as sensible as the US version, but different. They put the complex 2 smaller ring assembly on the harness, and one big ring on the risers.

Maybe he's practicing for a Mr Bill jump. Plenty of first attempts at them involve tumbling and pilot chutes going every which way past the jumpers.

Does it have LCD version 2.20 that's in the recall? You can check when it is turned on or in the paperwork that came with the unit (if that hasn't been lost before you got the unit). The bulletin also lists serial number range.

He got a little messed up there -- bit of an editing typo. He is writing about using front risers to try to get a little further upwind in a headwind, yet the title refers to being LONG on a spot. So unless he redefines the problem as planning to land out upwind, and make it upwind past a tree line, the title about being long has nothing to do with the subsequent text.

This is quite simply wrong, and is a common misconception. Wrong, wrong again. [Edit: I'm now not actually sure which part of the original unedited quote you were saying was wrong -- rears into a headwind, or spiralling. Your use of quotes didn't distinguish on that point. In any case:] I would indeed GENERALLY advise noobs to face into the wind and not spiral down. It is more likely to work I bet. In rushing to get down, people may underestimate how far they'll blow back. Just like noobs taking the downwind leg of their pattern way too far in strong winds, or throwing in a 360 and then finding themselves way far downwind. But one can easily come up with scenarios where the spiral down works better. For example, compare two cases. Someone is on a big boaty canopy that does 25 mph, and sinks at an easy 800 fpm. They have 2000' of distance to drop through high winds (whether that's to near the surface or just a level where they abate). Let's say that in a spiral they can triple their rate of descent to 2400 fpm, or about 27 mph downwards. I don't know offhand what it might actually be, but I don't think that is overstating things even for a big slow draggy canopy. If our jumper is facing 35 mph winds, he's pushing back 10 mph and will be exposed to the wind 2.5 minutes, pushing back 2200'. If he spirals, he's only exposed 0.83 min, but drifting at the full 35 mph, and drifts back more, 3080'. The three times increase in descent rate didn't make up for the 3.5 times increase in drift rate. But, if the winds were an extremely strong 50 mph at altitude, he is faced with drifting back 25 mph or 50 mph. There, speeding up the descent rate 3 times is of a net benefit compared to "only" doubling the drift backwards. Facing the wind he drifts back 5500', but only 3650' if spiralling. So in conclusion, facing the wind is usually the way to go, in situations where you are only getting pushed back slowly. It may feel scary for a noob, but spiralling will then be bad because they'll drift with the full speed of the wind. But in extreme cases where you already are drifting back fast, and you can increase your descent rate by a greater degree than the drift-back increases, then spiralling will better. This applies more for the slowest canopies (accuracy, student) in unusually high wind conditions. Hope this mathematical treatment helps.

Answer for the noob-ish: Fine if you are the only one jumping out of the airplane. Think about the consequences if there are others, and either you or others try that tactic.... very dangerous. Plus usually you are doing things in freefall with others, then the option isn't there. If one cares that much about the spot, one should have looked before jumping! If not, do the freefall and track safely and deal with the spot after opening. Well, you can pull at the upper end of the reasonable range, but that's about all you can do. One can change things a little more if it is a matter of life and death. (Eg, there's a thread active about guys doing a beach landing, and one died after landing far out in the cold water.)

The re-watching is the interesting part, to see whether one liked a show only because one was young and immature, or it was the first show of the kind one had seen, or whether it really had some good qualities. I just started re-watching a bit of WRKP in Cincinnati, and so far it is surprisingly good, with views on social issues that aren't so dated that they would make one cringe.

I don't know about actual German accident rates, but they've had many years to get used to the driving discipline and norms of behavior applicable to driving where there are lanes of traffic doing significantly different speeds. At least 85 mph would presumably be in easy enough to drive areas and it would be only a small change in existing behavior.

While the 'facts' don't all add up well, I understand that it can be tougher when jumping a big canopy. (I used to jump an accuracy canopy loaded .65 in all conditions as my regular canopy.) I'm doubt the spot was any good to start with. It's not likely have been fine for someone lazily circling from a 2500' opening but impossible for someone open at 4500' with say a 25mph canopy in a 50 mph wind. Maybe there were really strong uppers that weren't affecting most people under canopy much, or the spot was short anyway because most canopies could deal with the wind. And had you checked the winds before you went up, knowing you'd pull higher? And as someone else asked, where were you in the exit sequence if you were planning to pull higher? Getting on front risers when facing the wind can help, but it might only help by who knows 3-5mph on a big canopy. You can hold that for ages if you really want, but usually there's not much point in wearing your arms out if you're still going to be in some big field downwind and be hoping for a car ride back. If front risering is the difference between making a field and blowing back into 80' trees, then go for it. Nothing wrong with staying facing the wind a long time to minimize blow back, but you do need to know what's behind you soon enough to plan safely where you'll land. So to follow what others have said, if the DZ has more obstacles downwind or you're a noob, you may turn at least somewhat off the windline early, so that your landing won't be closer to the DZ, but is much easier to plan safer. Nothing wrong with a big canopy in high wind; but you do have to plan ahead a little more.

That's interesting. I don't know either way, but many of us skydivers would think there to be two separate but related transactions -- someone buys gear off you, and it is theirs, just that it is sitting at your house. Then they pay you to ship it to them any way they like. If a delivery truck with the package drives off a cliff, it's the other guy's canopy at the bottom of the canyon, not yours. However: The wikipedia entry on FOB (relating to shipping) is instructive and notes how the UCC has changed, so there are more options when it comes to determining at what point an item becomes the buyer's responsibility and no longer the seller's.

Or one could tie the bag on to a line like a removable RDS. Those things aren't entirely snag free, and stowing is an issue if attached to a non-removable slider. But something could be sewn up so that it the bag & line can be removed from the slider. It sounds like Nigel wants a reserve that's cheap enough to be taken out of service as a reserve -- find an old canopy in that case.

How about asking for 20 minutes of piloting an Airbus 380 if over 50? That'll really weed 'em out.

On the freefall side of things, what problems are you seeing? Just a lot of instability and stiffness, or is it a matter of following through all the tasks for the jump, or what? [Edit: Hmm, I see we're in the tunnel forum. Not sure how to match that up with the issues brought up in your post that deal with freefall, canopy, and tunnel...]

As far as I know (and I'm not following this story closely), he might have once claimed to have been with the notorious Karla H., but later denied it. He sounds like someone who isn't above a little fantasy and lying.

Duck Soup. That's what would happen. Of course, going back to basics, you don't have to be stable to pull. Get the f. out of the plane and pull. (Belly-ish to wind would be nice.) Plenty of students and pilots bailing out have pulled unstable and were fine. Sure there are added risks of line twists down low or having a leg caught in lines causing a mal, but the risk of something going seriously bad is low, especially compared to the alternative. If you've done floats, dives, and are going to work on upright exits, also consider later trying out dives straight to the side. There one needs to be rolled left somewhat to be belly to wind. Belly doesn't have to fact directly forwards; partway forwards and down is OK. Oh, one more thing about exits that I think hasn't been mentioned: In a dive down or dive to the side, one doesn't want rotational momentum where one is pitching down. One wants to try more to exit on a certain angle and keep that angle, not exit with a lot of downwards pitching, which can keep going until the jumper flips over. If one is trying to clear the door sill and dive down steep one tends to have some rotational momentum going, because one does have to go from crounched in the plane to diving head down, but one tries to minimize the rotation. (And that's where arms out and legs up helps after exit.) To get an idea what I mean, maybe you've seen vid of bad old time BASE exits? Newbies at Bridge Day? Pushing off with a lot of "diving down" pitching puts jumpers over onto their back, especially with little airflow for control.

A female friend of mine in Florida was upset at the weirdness going on down there, what with the drugged up face eating incident recently. But soon after, we here in Canada had this case, with purported on-video killing, dismemberment, mailing of body parts to the headquarters of the main two political parties, all by a self-proclaimed bisexual porn star who then became the subject of an international man hunt. Who says things are always more boring up here in Canada?

I don't know how to diagnose all the possible issues but can ask some questions. (This is for a typical turbine aircraft like the Otter I think you may be using.) Are you ok on a simple exit like the back to the wind one mentioned? It's a very stable position not requiring a lot of careful limb placement, and doesn't have limbs spread far to the sides, minimizing instability if something isn't symmetrical. Are you ok if exiting from the floater bar outside the aircraft? If so, that suggests the transition from inside to outside is a problem. You don't have to demonstrate a front float fully outside the aircraft on a front step, but can have head and arms outside, and lower body inside the door and even braced against the back of the door, if you feel you are being peeled off by the wind blast. Lighter weight people can have a bit harder time pushing out cleanly into the airflow before starting to be twisted, if part of them is outside but a leg is still inside. Are you getting an aggressive launch from inside the plane, to try to clear the door quickly, avoiding being spun from being half in the breeze and half out of it? (You may have seen really aggressive launches by the jumper inside the aircraft in an RW formation jump or AFF instructional jump.) Or do you get out of the plane cleanly but then are not belly to wind and thus end up rolling or flipping? Do you flip when diving down aft to chase someone? That's a common issue, where it is better to break the exit down into a clean exit straight out to the side, rolled somewhat to be belly somewhat forward, and only then think about turning and dive aft. Can you go out with arms tucked up against the chest like an exaggerated mantis position (and legs kicked back tightly to balance the loss of arms in the breeze) ? That would take away the influence of any flapping arms and focus attention on a good arch and being belly to wind. Or do you present to the wind OK but your body starts a little kicking or flailing for a couple seconds as it isn't yet used to the soft sub-terminal air with "nothing to grab"? Are you "trying too hard" to get stable and moving arms & legs too much when it would be better to stay a little more still and trust the arch?

Ufk22: You're fine with your general understanding of forces, but I am pointing out that according to the proper use of the term lift (scientifically, aerodynamically, technically, whatever), we as skydivers are creating lift as soon as we deviate off a straight down flight path. So you are right that a skydiver may be creating a crappy little amount of lift that is not created like that of an airplane wing which would have smooth attached airflow accelerating over the upper surface of the wing, and where the high pressure underneath is a lesser part of the overall lifting force. Something blunt and stubby will indeed be relying to a greater extent on that high pressure underneath. Also, the forces will indeed be directed largely horizontally and not very much upwards -- so it isn't 'lifting us upwards' much at all. But I'm trying to teach that according to the way the terms are defined, it is still LIFT, whether or not pointed upwards, whether or not created largely by high pressure on the underside of a blunt object. Feel free to call it crappy, inefficient, non-airplane-like lift that is hardly pointed upwards much at all - but it is still called lift.

The case of the flying snakes , Chrysopelea paradisi, is definitely an interesting and tricky one. I'm looking at one of the journal papers that team wrote. They (the snakes, not the researchers) do seem to stay fairly flat relative to the horizon but the angle of attack varies a lot. The very start of the flight is nearly flat to the horizon due to a good push off, then it gets very steep before it gets much aerodynamic movement going, and then it begins to flatten out. Tests from a 10m tower weren't high enough to clearly establish an equilibrium glide at the end, but it tended to be about a glide ratio of 2.2 or better near the end, which is surprisingly good. During the glide the snakes do flatten their bodies somewhat, giving them something other than a circular cross section, something the is probably a key in creating decent glide performance. There are some subtleties in their body angle though, somewhat angled down early in the flight while dropping more steeply (not totally flat to the horizon!), later flatter with just the head angled down (for vision?), forebody flat to the horizon (angle of attack 20-40 deg.), and aft body angled downwards. Without trying to figure it all out, it is complex and not always clearly seen especially in that one video looking from the front and slightly below. That's my serious answer to your less serious post! Edit: There goes my Sunday morning as I start to read the research lab's other papers. The snakes flatten out their bodies much more than I thought -- turning them cross sectionally into quite an airfoil (and almost a sort of staggered biplane when S curved side to side.) Attached pic shows the flattening in a snake. We should stick with human RW jump tracking in this thread, though, because snakes don't take grips!

Fair enough. That's always been one of the tough parts about instructing, trying to figure out who will actually screw up. Incompetence on the ground is normally a reason not to go up, but if the ground work is competent enough, it can be hard to tell who will mess up badly when put to the test in the air.

I can explain lift a little more: We do generate lift -- it just isn't of the really efficient, strong type that you get off of an airfoil, where the lift can be many times stronger than the drag that's being created at the same time. Our lift is normally less than the drag being created. So when someone cups while tracking to "shape their body like a wing", they aren't actually functioning as a wing -- even if that body shape is actually useful in improving lift. Technically lift is the force perpendicular to the direction of travel, so it doesn't matter if it is lift like a properly functioning wing or not. And drag is parallel to the travel. So for example if one is descending under a ram air parachute, you are being supported in an upwards direction against gravity mainly by the lift, but also by the drag back along your angle of descent.. Lift isn't straight up, unless one is flying horizontally. If one can't create enough lift to plane out of a dive and fly level, it may not be much lift, or there's too much drag compared to the lift, but it is technically still lift.

If I'm with a tandem passenger after opening and point out a subsequent tandem deploying, I do have to explain to the student about the camera flyer -- who falls away and appears to be plummeting to his death in the fields below. 'Relax, they're still thousands of feet in the air...'

It does seem to me that a little extra head down angle at the beginning of the track makes sense, as that extra angle of attack will generate the horizontal speed quicker than otherwise. It may not be a popular concept but the physics makes sense. But, that steeper angle is not held for long, because (a) it isn't needed to provide a good angle of attack for horizontal acceleration once some horizontal speed has been achieved, and (b) keeping the nose down angle for very long will increase your vertical speed over time. As others point out, you don't want to drop down far below other trackers. Big way tracking with groups is a special case that's a little different, as there one is trying to stay with a group rather than tracking faster & further than everyone else. Staying flatter can also make it easier to see those around you and pick a safe flight path, if things are 'busy' at breakoff. Then starting off slower and without ones torso angled way down, provides a net safety benefit. As an example of not getting head down enough, I've seen a novice adopt a really flat tracking position right at the start, body cupped but "flat" in the sense of almost level with the horizon. He thinks he's in an efficient tracking position, not diving off steeply. But since he hasn't really moved yet, he barely starts to move, with his angle of attack close to 90 degrees. Very inefficient for starting a track. Let's say for example that someone in a good long efficient track has a body angle 10 deg. down from the horizon, and that's getting him a 0.5 glide ratio (which may even be conservative these days if there's enough time to accelerate, but breakoff tracks are often pretty time limited). The numbers are made up but in the range that people talk about. That glide ratio equals 27 degrees off the vertical. Thus his angle of attack is 90-27-10 = 53 degrees. What does that imply for the start of the track? At the very start, tilting just 10 degrees nose down would be less efficient, as that's an 80 degree angle of attack compared to the relative wind from straight below. To get the supposedly efficient 53 degree angle, he would have to start 37 degrees head down! But as soon as horizontal speed is generated, the body would quickly have to flatten out towards the horizon to keep the same angle of attack, until deep in the track he is at the 10 degrees head down. That initial 37 degrees down angle may seem excessive in practice, but shows how the angle relative to the horizon MUST change from the steeper at the start to shallower later in the track if one believes in a particular most efficient angle of attack. If one believes that the best tracking angle of attack is something far from 90, say 60 or under, then the conclusion is that the track would have to be initiated with at least 30 degrees down angle. The speed during the track doesn't matter as long as you can achieve that efficient glide ratio. Someone heavy might drop away a little from others, but if they fly by same method, the same glide ratio will get them to the same distance at pull time (even if that happens a bit sooner). (The light and heavy people should of course have have been able to match fall rates during the RW part of the jump, but still the heavy guy might have a higher fall rate for a given body position.) Now since we are talking about low aspect ratio aerodynamics with no real airfoils, the lift & drag curves change very gradually with angle of attack relative to an airplane. For an airplane a few degrees difference in angle of attack can make a huge difference between "flying well like an airplane" and "totally stalled", but the changes are not as sudden for a blunt non-winglike object. Therefore there should be a big tolerance to different angles of attack, with a range of them providing similar lift and drag values. This is borne out by the wind tunnel tests with people that Hoerner did in the 1960s. (The numbers there also support some of the atmonauti folks' claims about good glide ratios even at steeper body angles than normally seen in a track, even if other claims of theirs are beyond the realm of rational physics.) The exact interplay between horizontal distance, vertical distance, and head down angles will depend on the altitudes available for the little tracking drag race, and the specifics of the lift and drag values. That's the tradeoff others talk about: If you focus too much on gaining horizontal speed by angling down too much, you will pick up more vertical speed. You'll get yourself further by your pull time, but if you get there 150 ft lower than others, the others will have about an extra second of freefall to surpass that distance by pull time, when moving say 80 fps horizontally. "Getting big" on breakoff is usually said to make sense. By adding surface area and flattening out compared to some tighter arched RW position, you'll add drag and gain a little extra height over the time one has to turn around. Whether it actually helps during the track is another matter. Some will say that of course it will, as with a slower descent rate you'll get some extra time during the track until pull altitude, and thus be able to track further. The problem with this is that if the efficiency of the track is the same, with the same glide ratio, then reduced vertical speed also means less horizontal speed. So both the faster and slower jumper get to the same place by pull altitude, just that the slower jumper gets there a second or so later. So I think getting big doesn't have the size of advantage as is sometimes claimed. Still, no sense in wasting altitude during the turn away from the formation, especially if everyone else is following that technique -- In that case get big for the turn around. Going back to the angle issue, in practical terms, consensus seems to be not to go very head down. It isn't particularly needed further into the track. Many will argue it shouldn't be done even at the start of the track. I personally find that getting a moderately steep angle quickly at the very start of the track is very useful to get fast horizontal acceleration right from the start. And I believe that it is supported by some tunnel data & physics. As discussed, not going too head down at the start can have other benefits in terms of keeping sight of others and doing what other people typically do. (As for my own tracking performance, I think I do rather well, and certainly am not dropping away relative to others on a track from a formation.) I've attached a photo I picked up somewhere showing a breakoff. It would be a good focus for a discussion, as it shows some fairly steep angles at the start of tracking, people really working on getting the horizontal speed going. (A few have dropped away too steeply compared to others.) I don't know if some people would consider the head down angles too steep to start with. Part of the confusion in this whole issue is whether "steep" means a steep flight path or a steep body angle.