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Showing content with the highest reputation on 03/21/2021 in all areas

  1. 2 points
    Semi Stowless Bag Review by Sandy Grillet I first started jumping the semi-stowless bag from UPT with the two locking stows and 4 tuck tabs, prior to them going into production because the designer wanted his design to be field tested using mostly an everyday jumper with what he thought would be typical skydives and pack jobs. I make 325-350 jumps each year. Roughly 1/3 of which are camera jumps - filming tandems. The rest are belly jumps as 4 and 8 way training, competing, coaching and FS organizing at boogies and events. I make use of packers for about 275-300 of my jumps (one of the reasons for the designer to give me a prototype of his bag). I now have more than 2500 jumps on the semi-stowless bags using Katana 120s, Velocity 103s and Valkyrie 96s. I have zero jumps (that means none) on wing suits. So my opinion is based on my personal experiences and my general knowledge of skydiving and deployment sequences. I have nothing but good things to say about the semi-stowless bag. It is essentially set up the same as a reserve bag except it uses a flap with tuck tabs for figure-eighting the lines instead of sliding them down into a pouch. This allows the packer to see what the lines look like as they are being figure-eighted - a good thing IMO. As recommended by the designer, I use large rubber bands for the two locking stows and double wrap them around no more than 1 1/2 inch of line bite. Some people will tell you double wrapping is not a good idea and may cause bag lock. This is a myth (assuming the use of large bands and the proper maintenance of your pilot chute and kill line length). I've been double wrapping large bands for 18 years on all my stows (locking stows included) even before the semi-stowless bag). I love the openings of the semi-stowless bag. I've had mostly very controlled on heading openings. Any off heading openings (90-120 degrees) usually happen on my pack jobs because I've been told I sometimes pack a bit hastily. Thank God for packers. The bag does allow you to get to line stretch quicker and cleaner than a conventional bag. I like this because I believe the majority of line twists start and are caused before the canopy comes out of the bag. Most jumpers replace the rubber bands only when they break or are extremely close to breaking. How many times have you wrapped a band around a line-bite thinking "come on don't break..... just hold for one more jump"? This means our bands are generating varying levels of force on our line bites. Some hold better and longer than others due to better (newer) strength. This imbalance of line bite strength often initiates rotation of the bag as the lines play out causing line twists. I believe the single wrapping of line bites sometimes allow the lines to deploy out of sequence allowing one or more lines to sneak out early and wrap around another line bite which can and has caused bag locks and hard openings. I also believe too much line bite helps cause line twists and out of sequence line deployment which can also cause line twists and bag lock. I've seen footage of quite a few opening sequences using high speed cameras, which means you can slow the footage down by roughly 2/3 of a normal video camera slow motion. The footage is quite enlightening. I think most people would be shocked to see how much bag dance and out of sequence line deployment is actually going on above our heads. Now, this doesn't mean that it happens all the time but it does happen pretty regularly. It also does not mean that it couldn't happen with the semi-stowless bag but the design is such, and testing along with hundreds of thousands of jumps has proven that bag dance and out of sequence line deployment is dramatically reduced to almost nothing. I like my lines to come out quickly and cleanly (like a reserve) so my canopy can hit the air with the greatest chance of an on heading deployment from the bag. After that, it's a matter of how well you packed and placed the canopy in the bag (especially the control of your slider), how well your canopy is in trim (lines), your body position during deployment and the design and wing loading of the canopy. As I mentioned earlier, you do get to line stretch quicker but it does not cause faster or harder openings. The openings are controlled by the slider and the packing (and canopy design). If a person gets a hard opening it's usually because the slider was not well controlled during the packing and bagging process. There can be other factors but it's almost always the slider. The semi-stowless bag does not affect the hardness or softness of the openings. It only affects the speed to line stretch which I like. It also allows the lines to play out in a more orderly fashion. We must remember, we only use rubber bands to keep the lines in place until they are needed and then to allow them to play out in a relatively orderly fashion in what is otherwise a fairly chaotic couple of seconds. But those bands can and do create other issues as I mentioned above. The semi-stowless bag does exactly the same thing but simply allows the lines to play out more consistently. All of this can and has been debated by those who are naysayers. And I believe healthy, sensible, civil debate is good and necessary for further development of ideas in our sport and gear. And I welcome the debate by those who have actually given some rational and original intellectual thought to this or any subject. Of course this is just my humble opinion – Sandy Grillet Full disclosure >> I am a UPT Vector dealer.
  2. 1 point
    Took me long enough, eh? Wendy P.
  3. 1 point
    I wrote this for a science forum a while back. I am reposting it here because with the recent additions of woo to the forum, people might be interested in my take on how to quickly determine if you're reading nonsense or not. Warning - it's long, since it was the result of a collaboration and other contributors added some material as well. ------------------------------------------------- Top Signs you are Reading Woo Cranks often enjoy posting on science forums. Once they feel the thrill of making up some pseudoscientific woo, telling it to a friend and having the friend think they are clever - they come on line, find a science forum and post away, hoping for kudos and compliments on their imagination and intelligence. We see them here all the time. But how can you tell a true crank from someone who is just confused, or someone who has a reasonable idea that is just not developed? How can you tell plain old errors from woo? Below is a guide to help with that decision. It lists several characteristics of cranks. If you see one of these characteristics, be wary. If you see several, well - either ignore the fellow or have some fun with him. ============================ 1) The Einstein gambit. This gambit is perhaps the most popular attempt that cranks use to justify their woo. "Sure, they're laughing at me, but they laughed at Einstein too, you know!" By equating his situation to that of Einstein, the crank hopes to make it seem that his intelligence is akin to Einstein's - thus granting more validity to his woo. 2) The sheeple claim. Once a crank uses the word "sheeple" for the first time - to distinguish his own brilliance from the dull conformity of all the other "sheep" on a given forum - you know he's all woo. Use of this word is nearly inevitable for some types of cranks, especially 9/11 truthers and UFO believers. 3) The mathematical obfuscation. Often, cranks attempt to "prove their point" by throwing a bunch of math on the forum. This can be done several ways. Most commonly it's just unrelated math - constants with improbably large numbers of significant digits is a good clue here. More clever cranks will often use unrelated but accurate math to support their woo. For example, someone claiming zero point energy might post a few derivations of Maxwell's Equations to attempt to prove his point, then claim "if I'm wrong, show me where the math error is!" Support for tools like LaTex increases the odds he will try this, by making it easier to post equations. 4) Webster Rescue. Often when a crank is losing an argument he will resort to redefining words to try to ameliorate a previous error. For example: "The results you have presented show greater than 100% efficiency, which is thermodynamically impossible." "Well, really, what's the definition of efficiency? Can't it mean that . . . " He will then search out various online dictionaries until he finds a definition that is at least not entirely clear, at which point he will claim that that's the definition that is in common use. 5) The retcon. In comic books and science fiction, the "retroactive continuity" trick is often used to clear up previous continuity problems.. It is in effect saying "what REALLY happened is . . . ." Perhaps the most famous retcon is in episode V of Star Wars, where Obi-Wan tells Luke "well, yes, I told you your father was dead, but in fact turns out he's Darth Vader due to this complex explanation." On-line, people often use this angle to claim "Yes, I may have said this, but what I really meant was . . ." For example, a 9/11 conspiracy theorist might claim that no steel building has ever collapsed due to fire. When examples are presented, he might change his story to "what I REALLY meant was that no TALL steel building has ever collapsed; that was obvious from my post." 6) The secret government conspiracy. Sometimes when a crank is challenged, and he feels he is unable to defend his point further, he will pull out the government conspiracy. He WOULD have more proof for his claim, you see, but the government is trying to suppress the information because blah blah blah. In general you will get no more useful information after this point, since if you try, he will accuse YOU of being part of the conspiracy. 7) Occam's Glue. In general, Occam's Razor describes the general rule that the simplest explanation that explains something is usually the correct one. Cranks use a version of that I call Occam's Glue - if something CAN be the explanation, it must be the explanation, even if simpler explanations suffice. UFO believers use this one a lot. "Yes, it could have been aircraft lights, or a meteor, or a planet, or low clouds - but how can all those explanations always be true? Some MUST be space aliens." 8) Woo prejudice. Oddly, most cranks will reject other people's woo quite strongly even when it is closely related. "There's no possible way those objects could be space aliens. They were clearly angels." This, while common, unfortunately does not help distinguish a crank from anyone else, since most people reject woo once it's clear that that's what it is. 9) Magical thinking. If part of someone's proof for their woo is the list of wondrous boons that this technology will grant mankind, the odds are high that he or she is engaging in magical thinking - the belief that a fervent desire for something will make it valid. Cold fusion believers, for example, often will list all the beneficial changes in society that cold fusion will bring about - and therefore declare that it is a real power source. 10) The Googleblast. Some cranks, facing skepticism, will make a somewhat late attempt to justify woo by searching the Internet for support. They cannot, of course, do any serious research, since that would tend to disprove their woo. However since anything is available on the Internet, they can always find something to at least marginally support them. Their cycle goes like this: Read (forum) Search (google) Pick (something that says something close to what they are claiming) Post (link to related information.) This read-search-pick-post cycle can go on for dozens of posts. They feel that by posting enough marginally related links they have found independent proof of their claim. 11) Cyberturfing. This is related to the point above. In politics the term "astroturfing" is used to describe the false "grass-roots" support that politicians can fabricate. By funding political media efforts and making it look like the support is coming from many independent voters, they can claim much wider support than they otherwise could. Likewise, cyberturfing attempts to generate so many emails, websites, links, studies and articles that the crank can point to the mass of material and say "see? EVERYONE agrees!" They will often use tactics like submitting papers to vanity journals so they can claim their woo is "peer reviewed." 9/11 truthers are especially good at this. 12) The Patriotism Ploy. Often a crank will attempt to confabulate his woo with some other laudable ideal like patriotism, family values, freedom, prosperity etc. Thus, rather than arguing the validity of his woo, he can argue the desirability of prosperity - which is a much easier argument to make. For example, a climate change denier might say "you can't believe in climate change! If you do it will bankrupt the US and make Al Gore rich. Do you really want that?" 13) Quote-mining. Often cranks will search out quotes from well-respected people to support their position (the classic "appeal to authority") - and often will not be able to find the support they want. However, a carefully extracted quote might make it appear that they have such authoritative support. The most popular is a quote from Charles Darwin, ofen used by creationists: "To suppose that the eye . . .could have been formed by natural selection, seems, I freely confess, absurd in the highest degree." The next lines then go on to explain how it is NOT absurd, but since cranks often gather most of their information via the above-mentioned read-search-pick-post method, they will generally miss that. 14) Prove Me Wrong. Cranks who propose an unusual theory (say, that UFO's are space aliens) will often not listen to alternative explanations that better explain the data. Instead they will propose their woo and ask "can you prove that that's NOT what's happening? Can you prove that that sighting was just a weather balloon?" This lets them sit back and wait for someone to provide an impossible level of proof for the more-reasonable explanation. 15) As seen on TV! Links to Youtube videos are one of the hallmarks of cranks. Whether this is due to cranks getting most of their information from videos, or whether it is due to the fondness of conspiracy theorists for Youtube, masses of Youtube links are one of the most common signs of the crank. 16) The argument from incredulity (i.e. "if I can't understand it, it is incorrect - and thus the explanation that I DO understand must be the correct one") is very common among cranks. Since they invariably have a very high impression of their own intelligence, any theory/explanation/process they do not understand must be incorrect. And last but not least: 17) The Grand Trampling Exit. Often cranks, once they have realized that they are not going to get kudos and attaboys for their unconventional thinking, will make a "final post" that is usually along the lines of "you're all a bunch of idiots! I'm going to leave this once and for all, and deny you all the pleasure of my company. Instead I am going to post on a board where intelligent people have open minds!" Reading the Grand Trampling Exit, readers of the forum might be tempted to breathe a sigh of relief as the signal to noise ratio improves. However this relief is often short-lived. Cranks love attention, and thus more often than not they come back sometime later, often with a statement along the lines of "well, I just had to say one more . . ." or "I realized you wanted me to leave, so I'm going to stick around to get back at you!" ===========================
  4. 1 point
    Phys.org posted another article, "5 ways to spot if someone is trying to mislead you when it comes to science". It's mostly about covid-19, but it's also applicable to a particular poster here. The 'us versus them' narrative "I'm not a scientist, but…' Reference to 'the science not being settled' Overly simplistic explanations Cherry-picking I highly recommend the article, see if it reminds you of someone.
  5. 1 point
    Rocky, I m sorry that CV-19 kept you from seeing Mr. Douglas back in the air.... I can assure you that we will do our best to get him flying again, in 2021....! BSBD EET Brother
  6. 1 point
    Having an AAD firing if I go below landing altitude is a NO-GO for me. And the explanations the manufacturer gives when analysing 3 devices who went under the same circumstances and had different reactions (2 fired, 1 did not) are also important and a case of trust loss in the device and in the manufacturer. i am not naming them, but in that case, 3 rigs were placed inside a minivan and the AAD’s were still ON. That was a user mistake as the manual stated that they should have been switched OFF. Said minivan drove approximately 300ft up a hill, and down approximately 1000 lower than the departure point. During the descent, 2 units fired and 1 did not. explanation from the manufacturer was that the 2 units had met the firing parameters by descending too fast at activation altitude. As you claim to be an engineer, I will let you do the maths to calculate the steepness of the hill, knowing that the driving speed of the minivan did not exceed 120 km/h (around 80 MPH). They were never able to explain why the 3rd unit had not fired. Also, they weren’t able to justify why an AAD should stay in “airborne “ mode for an undefined period of time. I had a customer wondering why his AAD was still ON at home, 2 weeks after his last jump. He lives 2000ft above the DZ. Yes it was user error (should have turned it OFF). But which aircraft stays aloft for 2 weeks ? (I know there are a couple, but hardly ever used for skydiving). Have another couple of grudges against them which makes me not want to use them.
  7. 1 point
    https://www.youtube.com/watch?v=Ipf6tLO43n0 Despite false rumors, see claim above, the old school classic D bag is alive and well. Perhaps it's an east coast thing?! That being said, the newer tech is taking over, because it works... ANYONE selling gear still sells the regular old D bag. Welcome back.
  8. 1 point
    I wouldn’t say Biden is lying, I just don’t think he understands what he is saying.
  9. 1 point
    It comes down to this: You have the opportunity to design and jump a harness and container with a reserve, AAD & Main of your choosing. Why wouldn’t you choose reserve components that have optimal fit? My opinion is you should decide on an appropriate sized reserve and then consider which reserve of that size you want to buy based on price you are willing to pay. THEN, match the reserve container size with an optimal fit for that reserve, not the other way around. Then, decide on a main based on your desired flight characteristics. THEN choose a WL based on your desired flight performance and piloting skills. THEN choose the container based on those components.
  10. 1 point
    Almost ALL of our (the US) reduction in CO2 emissions can be attributed to natural gas replacing coal for power generation. Of course this was only possible because of the fracking revolution.
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