poohbeer 0 #26 April 23, 2003 airlocks? What's that? (newbie here) ------- SIGNATURE BELOW ------- Complete newbie at skydiving, so be critical about what I say!! "The only thing necessary for the triumph of evil is for good men to do nothing." Quote Share this post Link to post Share on other sites
Tonto 1 #27 April 23, 2003 Better to be down here wishing you were up there, than up there wishing you were down here. If you're a student, stop jumping when lower students are grounded. I'm an AFF instructor, and I won't jump in conditions that are too windy/bumpy for students. Always another day, if you make it through this one... tIt's the year of the Pig. Quote Share this post Link to post Share on other sites
crazy 0 #28 April 23, 2003 QuoteYou need as much speed as possible. If you are talking about collapses, there is an argument against speed. A canopy will collapse because the accumulation point (the point of highest pressure) moves away from the openings in the nose. When this happens, faster means more pressure outside; this means that the canopy will deflate faster. Still about collapses, there might be an argument for slow speeds: the effect of the accumulation point moving to the top skin is much worse than when it moves to the bottom skin. So, it is safer to fly with the accumulation point a bit lower. One way to achieve this is to increase the angle of attack (which reduces the speed). Of course, the limit is the risk of stall. Now, if you are talking about the comfort of the flight (feeling the humps and bumps in turbulences), then you are absolutely right, faster gives a much more even flight. Kind of driving faster on dirt roads to reduce the discomfort of the uneven surface. The speed is more steady because you spend less time in each turbulence. In addition, each turbulence has less effect on the vertical speed because the lift is proportional to the square of the speed. If you fly at 10mph, a gust of +10mph will multiply by 4 the lift of the canopy; if you were initially flying at 30mph, the same gust would multiply the lift by less than 2.-- Come Skydive Asia Quote Share this post Link to post Share on other sites
nacmacfeegle 0 #29 April 23, 2003 "Better to be down here wishing you were up there, than up there wishing you were down here. " Tonto said it, and many others before him. Its an old phrase that is worth bearing in mind. Skylark, you are from London, Dust Devils are rare in the home counties, so I wouldn't get too hung up them yet. Avoidance, avoidance, avoidance....So I won't get into half brakes vs full flight arguments. I don't know how many jumps you have, but if the winds are too squirrely (gusty, unpredictable) the chances are your CCI will keep you on the ground. If he/she doesn't, there are a few tell tales you can watch out for to avoid turbulence. Watch a load landing, preferably a load with jumpers who handle canopies the same way as you do, ie there's no point watching cool swoopers and thinking "gee I could do that". Watch how their canopies twitch, accordian, etc, especially at low level. Watch the wind patterns on the windsock, or long grass. If the windsock is pretty stable, chances are the wind won't be gusting and the turbulence is easier to predict (it will still be there, it just won't be moving around as much). Know what the wind does to your windsock, eg it may be that at 18mph the wind sock has a stiffy, etc. So you can tell the wind speed by looking at the sock. Similarly if the windsock is thrashing around, its almost certain that there will be turbulence out there, somewhere waiting to bite you. Land in the student area, the terrain is normally more open, and relatively stress free. Landing safely is the only thing that really matters on any skydive. Its better to take a walk back than be carried. Avoid 'following' someone else in a pattern close to the ground (wake turbulence). Wake turbulence may not collapse your canopy, but it could distract you momentarily, and put the willies up you if your not expecting it. Watch out for the factors that develop turbulence such as buildings trees hedges, parked cars, etc. I use a 1:10 ratio ie a 50 ft high hangar can generate 500ft of turbulence downwind, buildings wit sloping roofs such as barns, hangars, etc, and can also create "rolling turbulence" out to the side which is very difficult to predict. You can take a walk out onto the landing area between loads to 'feel' the gusts. Jump at a DZ that is not prone to turbulence, eg a nice wide open one like Netheravon. Avoid flying over anything that might give off thermals such as runways, roads, tarmac areas, dark roofed buidlings etc. Thermal turbulence is less likley to slam you, but again it can be distracting and a little unnerving for the unwary. Also when the winds are dodgy, avoid flying over anything you don't want to land on. Watch the weather forecasts, and know how they are likley to affect your local area. Be sure you don't get into the habit of reaching out for the ground with one leg, this can often be mistaken for "a sudden gust caused me to veer offline on landing". Shifting your body weight in the harness like this can cause offline landings. If you are going to jump in iffy weather make sure you know all about your off landing areas, the frequency of off landings goes through the roof in marginal wind conditions. Know how to get back if your deep (upwind), or short (downwind). Last but not least, watch the experienced jumpers, AFF instructors etc, if they are hanging back watching the first load or whatever, ask yourself why...... >edit to add links etcMaybe they are reading stuff here.... http://www.zct.co.uk/skydivemag/pages/articles/dec99/landalone.htm http://www.zct.co.uk/skydivemag/pages/articles/oct02/canopytraining.htm http://www.zct.co.uk/skydivemag/pages/articles/dec00/canopyskills.htm http://www.zct.co.uk/skydivemag/pages/articles/dec01/sizematters.htm http://www.zct.co.uk/skydivemag/pages/articles/aug01/yourwing.htm http://www.zct.co.uk/skydivemag/pages/articles/apr00/toast.htm#shuffleturn http://www.zct.co.uk/skydivemag/pages/articles/jun99/canopycontrol.htm See also PDs website for canopy handling in turbulence, getting home from deep spots etc. http://www.performancedesigns.com/education.asp Bryan Burke also has some great stuff on Eloy's website. http://www.skydiveaz.com/resource.htm -------------------- He who receives an idea from me, receives instruction himself without lessening mine; as he who lights his taper at mine, receives light without darkening me. Thomas Jefferson Quote Share this post Link to post Share on other sites
Tonto 1 #30 April 23, 2003 Now THAT is usefull feedback. Lessons learned. Thanks. tIt's the year of the Pig. Quote Share this post Link to post Share on other sites
fudd 0 #31 April 23, 2003 Wow.... The picture on that page is awsome. Just hope he hits the water....ouch There are only 10 types of people in the world. Those who understand binary, and those who don't. Quote Share this post Link to post Share on other sites
crwmike 0 #32 April 23, 2003 I agree with himself. Course I think the real reason not to jump airlocks in high winds is trying to deal with that muther after landing :) Skies, Michael QuoteYou realize that Brian Germain himself gets fairly annoyed when people will say they'll jump in turbulence b/c they have airlocks, but wouldn't in an open canopy. His thoughts are that if you won't jump an open nosed canopy in those winds, then you shouldn't jump an airlock in them either, since it'll still be dangerous. Quote Share this post Link to post Share on other sites
USPA 0 #33 April 23, 2003 Mostly I agree with you, but not on this one... First I didn't say do agressive aproaches (not a good idea to deform your wing, when you need it most) Second the moment my wing stops moving air, I fall to the ground.The trouble with skydiving; If you stink at it and continue to jump, you'll die. If you're good at it and continue to jump, you'll see a lot of friends die... Quote Share this post Link to post Share on other sites
riddler 0 #34 April 23, 2003 QuoteThe "canopies resist turbulence better when they're going faster" thing The logic(?) I have heard behind this is that if it is a patch of turbulence, you just get through it faster. I don't know how logical that is. I do know I don't like turbulence and I like to get it over with as quick as possible.Trapped on the surface of a sphere. XKCD Quote Share this post Link to post Share on other sites
billvon 2,476 #35 April 23, 2003 >The logic(?) I have heard behind this is that if it is a patch of >turbulence, you just get through it faster. You do indeed get through it faster. You also experience greater turbulence. Turbulence is change in windspeed over time which, at a given velocity, is the same as change in windspeed over distance. If you cover that distance faster you see that change more rapidly, thus you see more turbulence. I don't think the issue is getting through turbulence quickly; I've seen canopies collapse in a tenth of a second. I think the issue is getting through the turbulence without your canopy collapsing. Quote Share this post Link to post Share on other sites
jdfreefly 1 #36 April 24, 2003 Bill, In no way is this a challenge to your knowledge. This is what I have heard: 1) When the old squares first came out, it was true that flying in half/quarter brakes helped to keep them pressurized. It was explained to me why this was, but I cannot recall the explanation. This is no longer true of todays canopies and flying in half/quarter breaks only robs you of airspeed and thus depressurizes the airfoil. This in turn makes it more vulnerable to turbulence. 2) When jumping in turbulence with a high performance canopy, speed is your friend. The faster you are moving, the more riggid your wing becomes, the less vulnerable it is to turbulence. This speed SHOULD NOT be achieved by a hard front riser maneuver. The best thing to do is a gentle front riser carving maneuver to build up speed without deforming the airfoil. This is advice given to me by people with over 10,000 jumps and could still be incorrect. Still, the safest option is to stay on the ground when in doubt. Methane Freefly - got stink? Quote Share this post Link to post Share on other sites
sducoach 0 #37 April 24, 2003 But, take Auggie's advise. When in doubt............ sit down with the "old skydivers" and watch the "experts" go. Blues, J.E.James 4:8 Quote Share this post Link to post Share on other sites
PhreeZone 15 #38 April 24, 2003 Pulling on the front riser at all distorts the airfoil shape. Toggles up speed is the max you should do in turbulance.Yesterday is history And tomorrow is a mystery Parachutemanuals.com Quote Share this post Link to post Share on other sites
nacmacfeegle 0 #39 April 24, 2003 PD agree with Phree on this one, from the many links I posted above......In thiscase, PD's website, under FAQ...taadaaa "What should I know about flying in turbulence?" "Avoiding turbulence is the best policy. However, if you find yourself in turbulent conditions, we recommend flying at full glide. At full glide, the canopy will penetrate through turbulence better, and be less affected by it. Making control inputs very smoothly, and only when absolutely necessary, will also help. Be sure to avoid small, abrupt left-right toggle inputs. Contrary to what some people have been told, flying in brakes does not necessarily help keep the canopy pressurized. Aerodynamically, the canopy is actually more susceptible to turbulence in brakes. Years ago, flying in half brakes seemed to make some older ram-air canopy designs more stable in turbulence, though they were obviously very different from modern canopies. Flying in brakes is definitely not the best technique to use with the canopies we're flying today, although a lot of skydivers are still told to use this technique. In addition to flying smoothly at full glide, it is vitally important to keep the canopy from turning toward an obstacle or diving into the ground if it has distorted or collapsed in turbulence. If you experience a partial collapse on the right side, for example, it is important to stop any turn or dive to the right that might result. To keep the canopy straight, you may need to have the opposite toggle pulled down quite far. Do whatever it takes to keep the canopy from diving into a steep turn while it is collapsed. This will reduce the altitude loss, thereby giving the canopy more time to re-inflate. With reasonable control inputs, most canopies will re-inflate on their own in this type of situation, altitude permitting. Pumping one or both toggles to re-inflate the canopy, instead of controlling your heading, will usually just make things worse. Pumping doesn't re-inflate the canopy, although holding both toggles down for a moment can help the end cells re-inflate more quickly if you are at a high enough altitude. If you are close to the ground, your main priorities should be keeping the canopy flying straight, flaring as well as you can, and making a PLF if necessary. Picking a good landing area is also important. We're often surprised when people land close to buildings and obstacles on a windy day, get tossed around by turbulence, then go back up and land in the same place on the next load. It also helps to be realistic about your own capabilities. Sometimes staying on the ground until the wind calms down is the wisest choice. It’s better to miss a few loads on a nasty day than spend the next six months on crutches. Please keep in mind that the information on this FAQ page is based on our knowledge of canopies in general, and the canopies we build in particular. Canopies designed by other manufacturers may have specific characteristics that are very different from ours, and this advice may or may not apply to them. Is it safer to be under a smaller or larger canopy when flying in turbulence? back to top The fact is that any canopy, or anything that flies for that matter, can be affected by turbulence. It can even cause problems for rigid-winged aircraft, from Cessnas to 747s. Larger canopies tend to be affected by turbulence more easily. A jumper flying a large canopy may feel some significant bumps on days when people flying smaller, faster canopies feel hardly any turbulence at all. On the other hand, if turbulence causes a partial collapse on a small, fast canopy, it can result in a far more dramatic (and dangerous) turn and a greater loss of altitude. We've seen end cells fold under on larger canopies without having much effect at all on the canopy's flight path, while a similar situation has turned smaller canopies into Mister Toad's Wild Ride. This is basically the trade-off between flying a large or small canopy in turbulence. Wing loading also has an effect on how a canopy handles turbulence. A heavy jumper might fly through some turbulence and only feel a few moderate bumps, but a very light jumper flying the same canopy through the same turbulence would probably feel a much greater effect. We feel it is best for you to choose the size and type of canopy you feel comfortable with when flying in normal conditions, and understand the benefits and limitations of that particular canopy when flying in turbulence. You should also understand the best techniques for flying in turbulence, and make informed decisions about the kind of weather conditions you're willing to fly in." Peace folks.-------------------- He who receives an idea from me, receives instruction himself without lessening mine; as he who lights his taper at mine, receives light without darkening me. Thomas Jefferson Quote Share this post Link to post Share on other sites
jerm 0 #40 April 25, 2003 QuoteI know I wouldn't be hooking it during turbulant winds. I just see people doing it and getting away with it. Their philosophy was keeping the canopy pressurized. If it works for them, go for it. I'm not ready to do that yet. there's a fine line between keeping the canopy pressurized and upping your risk factor by flying faster... as for "i see people doing it and getting away with it", please see my signature. Landing without injury is not necessarily evidence that you didn't fuck up... it just means you got away with it this time Quote Share this post Link to post Share on other sites
wildWilly 0 #41 April 25, 2003 Hi Mike, Just because I have air locks doesn't influence my decision to jump in winds that I know are turbulent. I will be one of the first to decide to stay on the ground. It is when I don't know there is turbulence that I appreciate having air locks. So yes I do feel safer with air locks than without. Willygrowing old is inevitable, growing up is optional. Quote Share this post Link to post Share on other sites
wildWilly 0 #42 April 25, 2003 Quoteairlocks? What's that? (newbie here) Air locks are an invention by Brian Germain that he has incorporated into his canopies that allow air to enter through the nose of the canopy but won't allow the air to leave ( keeping the canopy pressurized and inflated) Ckeck out his web site for more info http://www.bigairsportz.com Blue Skies, Willygrowing old is inevitable, growing up is optional. Quote Share this post Link to post Share on other sites
