bgrozev

PD has good documentation for their RDS, I think it answers all your questions: https://www.performancedesigns.com/docs/RDS_operational_instructions.pdf https://www.performancedesigns.com/general-faqs/#line-types

Crossfire2 129 loaded at ~1.5: 8mph with brakes stowed, 13mph in full flight Katana 120 loaded at ~1.6: 16mph with brakes stowed, 18mph in full flight Based on data from flysight

I estimate the number of jumps I expect I can make at different locations, and weigh it against the travel time and price. So I find myself checking the weather forecast for the 3 potential locations in my area for a specific period of time (e.g. Saturday through Monday). It would be nice if I could have all that in one place. Having a list of events (including closed days) would also be useful. And also accommodation options.

Six years ago (before I started skydiving) I dislocated my left shoulder multiple times, and finally had the Bankart Repair operation. The recovery after the operation was long, but since then I haven't had any issues apart for some minor reduction in my range of motion. When I started skydiving and flying in the tunnel I was worried and wore a sleeve. But I did not feel any discomfort or instability, and the sleeve was cumbersome so I stopped using it.

Hi and welcome! It is unfortunate that you have heard this myth before you've even started. I'm afraid I might oversimplify a complex question here, but I think the short answer is: it is a myth, but many people believe it. I recommend the following video on the topic: https://www.youtube.com/watch?v=8INJxZEo4Ww Spaceland Dallas is a really really nice place (I've only been there a couple of times). As for advice: talk to your instructors. Many people will be happy to give you advice, but it will not always be good or appropriate for you, and in the beginning you may not be able to tell the difference. When in doubt ask your instructors. Welcome again, and I hope you enjoy the sport!

I'm a flat earther denier. I can't believe any of them are for real. I was also skeptical of their existence, but I found evidence. Someone I know announced a $100CAD award if someone could show him a "non-stop commercial flight from Australia to South America", implying that if such flights don't exist this supports the idea of a flat Earth (I have no idea how that is supposed to work, but that was the claim). Anyway, after 1 minute of googling and 5 days of arguing over whether flightview.com is a fake website or not, I did get my money (and I promptly donated it to the Planetary Society). I find this convincing evidence that the person is for real. Also, that person happens to be a skydiver. I myself would be uneasy on a plane with him since I think he is delusional. I'm curious what others think: would you jump with someone who shows such signs of delusions in online posts?

Here are my observations from flying a demo X-Fire 124 for two weekends. I don't have much experience flying different canopies, so instead of giving general characteristics, I'll stick to comparing it to my current canopy, a Crossfire2 129. I am just getting into swooping, and that's what I was mainly evaluating it for. This seems to be a common situation for people, so I hope this comparison will be of some use. I have an exit weight of 195lbs and the wing-loadings of the cf2 and xf are similar: ~1.51 and ~1.57lbs/sqft respectively. I only made 19 jumps on the X-Fire. The openings were quite different from other canopies I've flown (crossfire2, safire2s, sabre2). For the first few jumps I was opening at 10kft (and density altitude of ~14kft), at terminal, and they were a little sharp (FlySight data shows peaks of about 3g, but I am not sure it can be trusted). Not uncomfortably sharp, but close. I started to split roll the nose, and that helped a lot. If all openings are like this I would be happy, but I am slightly worried that any outliers (say, 50% faster) will be painful. Out of 19 openings, 16 were head-on (within, say, 30˚), one did a 90˚ turn, one did a 360˚ turn, and one did a 360˚ with line twists. The last one has two and a half twists, and it did not dive. That's not much data, but it looks good to me. I think my cf2 has a similar rate of >180˚ turns, and body position could be part of the reason. The brakes are stowed very shallowly, so popping one toggle doesn't have much of an effect. This is also apparent from the FlySight descent rate data: 12-13mph with brakes stowed, and 13-14mph with brakes unstowed. Compare with 7-8mph with brakes stowed and 12-13mph with brakes unstowed on my cf2. The canopy is overall more responsive to input than my cf2. For toggles and rears the difference is small, but for harness and front risers it is significant. The range of the toggles (from start of tail deflection to stall) is shorter, and they are heavier. Similarly, it stalls on rears with less input. I noticed some over-steer for front riser and harness turns, but not much (the cf2 doesn't over-steer at all, as far as I can tell). The toggles are a little bit twitchier, I needed to pay some attention to flare symmetrically. The front risers are heavier than the cf2. Once it enters a dive it is much easier to keep it diving by maintaining harness input. I can keep it in a turn indefinitely, while on my cf2 I can not even get a consistent 270 because it starts to recover unless I get it just right. However, once the input is released it seems to recover in a way similar to the cf2. With enough speed the cf2 recovers to flying completely level. The xf seems to take longer to recover, but at least on one occasion I see it go to a descent rate of just 3mph, and I suspect that with more speed it might go level too. I wish I had more time to test, as that was the part I was most interested in. In short, the recovery arc seems longer, but similar to that of the cf2. In a 90˚ turn, executed in a similar way I lose 380ft on my cf2 and ~450-480ft on the xf. But it's hard to compare because I didn't have time to make my turns consistent enough. It feels like there is more power in the flare than the cf2. The glide, thankfully, is nothing like a katana. It is perhaps a little steeper in full flight than my cf2, but not by much. It felt stable and steerable in deep brakes. All in all, I was happy with the canopy and I definitely like it better than my cf2 for my use (starting to swoop). I wish I could also compare it to the Crossfire3 and the Tesla.

It still probably didn't have as much an impact as the provocative works of secular liberal atheists at Charlie Hebdo. Who's to say that this wasn't the work of like-minded individuals? There's a huge difference between publishing a magazine for people to read if they so choose, and threatening people by leaving hateful signs on their property. Making fun of people on TV is OK, mailing death threats to them is NOT OK -- no matter how you choose to measure the "impact".

No you can't. It needs to measure the pressure at the ground in order to calculate your altitude. Absolutely. Completely wrong arm-chair reasoning on my end. Thank you for pointing it out. It does if you don't want to waste batteries. From the manual: ***NOTE: To save battery power, the screen display will switch OFF after 14 hours. However, the unit is still ready to jump. You should be turning your Quattro off at the end of the day and turning it back on before jumping. You're risking it being in jump mode with an incorrect reference pressure (if a front comes through during the night, for example) or being completely dead because the battery ran out. It's a good habit to turn all your digital gear on at the start of the day, check battery status, and let it calibrate for the current atmospheric conditions. That's also a good point. Thank you. Apologies everyone for drifting the topic. At least I did get some education out of it.

Crossbracing is a construction technique to have a more rigid and efficient wing, while using fewer lines to minimize drag. That's all it is. I am not ignoring words. If they claim to have made a "ultra high performance wing" But they don't. They wrote "creating a new class of ultra high performance, non-crossbraced wings". You removed a word from the middle of the sentence... I don't think this is what they meant. As you point out this interpretation doesn't make much sense because "crossbraced" refers to the way a canopy is constructed, and not its performance. I think the intended meaning is "a wing which has performance near the top of its class, and it's class is that of non-crossbraced wings", and I also think that's the most natural interpretation of the text they used. Similarly "an ultra high performance human-powered bike" is a bicycle with high performance when compared to other bicycles, it's not a bicycle which is faster than a Yamaha.

What does that have to do with this discussion? For a wrist mounted visual altimeter (which we are not discussing) I don't really care because a) I'm less likely to forget to turn it on, b) I will notice it is not working when I look at it, and c) I can turn it on in freefall and/or under canopy. I do have an audible (Quattro) which doesn't need to be turned on manually and I consider this an advantage. I simply provide this as feedback to the manufacturers.

Really? That's interesting. Most people comment that the recovery arc of Sabre 2 and Crossfire 2 is very similar. I flew a couple of times a Crossfire 2 and I had the similar feeling, but I didn't do any exhaustive testing. Have you flown a Katana? If so, how would you compare both? I made that comment. But my wording was more like "how can it be a transitional canopy if it is creating a new class of ultra high performance wings". My point was about being ultra high performance. An ultra high performance stepping stone doesn't make much sense in my opinion. Maybe it is simply a marketing gimmick that turned out to be too bold? You can't just ignore some of the words in the sentence: "creating a new class of ultra high performance, non-crossbraced wings" I have no idea if this is true or not, but the semantics are clearly different than "creating a new class of ultra high performance wings".

Some feedback: having to turn it on manually is a significant disadvantage for me. I was considering getting one for my second helmet, but if I have to remember turn it on I might as well move the one that I have between helmets.

And for some reason I thought you were trying to make a subtle point. It is academics who wrote the hoax article, academics who point out the problem with predatory journals, academics who analyze the peer review process and work to improve it, academics who go after academics when they act unethically. And the community as a whole accepts this as a problem. No one argues, for example, that publishers should continue this practice because it helps young scientist get publications and advance their careers. Many religious communities on the other hand seem quite happy to make excuses for all kinds of immoral and unethical acts, and protect people doing them, as long as it agrees with their agenda.

What an idiot. 200 miles of travel is approximately 130 feet. Well short of the claimed "five miles." No, the figure of 5 miles is correct (it is about 8 inches per mile, but it doesn't increase linearly). Expecting that the level would change in this way is of course ridiculously silly.

Emphasis mine. But publishes a 'paper' written by an algorithm that ties together random buzzwords.... http://www.acsh.org/news/2017/05/19/hoax-science-paper-says-penis-social-construct-worsens-climate-change-11302 *** A new team of hoaxers has struck again, this time in the journal Cogent Social Science. Even though the authors have already admitted to their hoax in the magazine Skeptic, the journal apparently is unaware. The paper is, for the time being, still available Cogent Social Science is the journal which published the hoax article, Skeptic magazine is where the authors detail their hoax: http://www.skeptic.com/reading_room/conceptual-penis-social-contruct-sokal-style-hoax-on-gender-studies/

http://www.skeptic.com/downloads/conceptual-penis/23311886.2017.1330439.pdf I have no idea what point you are trying to make, but it appears that the published has withdrawn the article: https://www.cogentoa.com/article/10.1080/23311886.2017.1330439

That's what I thought. But at 2:55 you can see there's no skates, just what looks like normal shoes. Great performance.

The relevant part of referenced document:

I'm curious to learn how she did it. She could have used equipment and later disposed of it.

You don't see the point of downsizing and you are happy with your current canopy -- where is the dilemma?

I wouldn't carry an additional device just because of this. I already have my phone with me when I jump, and so I am left with two problems: 1. How to quickly and easily provide my location to the DZ if I land off (I believe Burble already solves this). 2. How to do the same if I am incapacitated. I don't think there is currently a solution for the second problem (correct me if I'm wrong), but I think it is solvable. Here is one suggestion: the event of "landing" can probably be detected based on GPS. If the landing is found to be outside some defined landing area, alert the user and schedule an alarm. If the user does not respond and stop the alarm in, say, 30 seconds, notify the DZ (or someone else) with the location.

This reminds me of the damaged screen that I saw at a gas station recently.

https://www.youtube.com/watch?v=fst6brFx0xc If I'd seen this interview first, I would have thought this is the new Ali G "go-pro hero" character. "What do you say to people who want to follow in your footsteps." "Go for it, I'll teach you." I guess he's the top pro in his niche. He has, like, more than 7 illegal pool jumps on youtube now, and, like, you know, almost 90% success rate.

I haven't forgotten to turn my on yet (unless I forgot and then failed to even notice, which I doubt ever happened). I make a conscious effort to slow down, actually take a breath, and do a no-hassles check every time before I put my rig on. It only takes 20-30 second, which is not substantial even if I'm in a hurry. And when I am in a hurry, the very fact that I have to change speeds helps me to notice that I'm in a hurry and take a mental note. The way I think of it: this saves my life with probability epsilon, and saves me needless worrying on the way up with probability 1-epsilon.