stayhigh 2 #26 February 12, 2015 They all have the same flair, they all slow down enough to do stand up landing. Difference is one has longer flair stroke, making it less likely to stall on landing, vs the other has shorter flair stroke and some people will stall it prior to putting the foot down. I don't think OP has more powerful flair vs PDR, that's subjective. What is powerful flair anyways? Both slows down enough to have stand up landing. Is the other one not powerful? How so? If it has more "powerful" flair, does that mean canopy levels out faster given your length of flair stroke? This marketing lingo has to go, it only confuses people. How fast the reserve comes out and opens depends alot on packing, how long it has been in there, body position, and what airspeed you had during deployment of the reserve.Bernie Sanders for President 2016 Quote Share this post Link to post Share on other sites
gowlerk 2,216 #27 February 12, 2015 QuoteDifference is one has longer flair stroke, making it less likely to stall on landing Yes, but why does it have a longer flare stroke?Always remember the brave children who died defending your right to bear arms. Freedom is not free. Quote Share this post Link to post Share on other sites
hackish 8 #28 February 12, 2015 stayhighThey all have the same flair, they all slow down enough to do stand up landing. Difference is one has longer flair stroke, making it less likely to stall on landing, vs the other has shorter flair stroke and some people will stall it prior to putting the foot down. I don't think OP has more powerful flair vs PDR, that's subjective. What is powerful flair anyways? Both slows down enough to have stand up landing. Is the other one not powerful? How so? If it has more "powerful" flair, does that mean canopy levels out faster given your length of flair stroke? This marketing lingo has to go, it only confuses people. How fast the reserve comes out and opens depends alot on packing, how long it has been in there, body position, and what airspeed you had during deployment of the reserve. The optimum's design is completely different than the PDR. A different design is going to mean many different things, one of which is the shape of the airfoil. Different airfoils have different characteristics. I specifically asked a PD engineer why he thought the PDR did so well and had such a good run. His response was that they put a lot of effort and lot of testing into it. After they got it right they focused their energy on other types of parachutes. A flare is not subjective at all. It's real and quantitative. Aerodynamically the parachute will have different lift/drag ratios throughout the flare itself. These are quite measurable in terms of speed and descent rate. If I need to park my butt into a small clearing in the woods I'll take the parachute with the better slow flight characteristics thanks. It isn't correct to say that optimum is a PDR made from lighter material with a longer toggle stroke. -Michael Quote Share this post Link to post Share on other sites
pchapman 279 #29 February 12, 2015 QuagmirianI'm pretty sure the planform is exactly the same. It'll be other things they've changed like line trim, airfoil/panel shape etc. I was curious about that so went and looked at their product literature and line trim charts and was quite surprised at how little has changed. Whatever they've achieved different between the two canopies is due to subtle changes. (And perhaps a small amount due to the material, but that should affect packing more than inflated shape or aerodynamics, especially when new.) The spans and chords and aspect ratios are identical for identical sizes. Maximum weights are increased for some models of Optimum, generally for the larger sizes to expand above 254 lb, but also in one smaller canopy, moving the boundary between 254 lb and 220 lb certification down by one size. (Opt 113 is good for 254 while the PDR 113 is only for 220.) Maximum suggested weights are generally the same. (However: Higher for those Optimums where the maximum certified weight went up. For very small reserves, occasionally the Optimum allows a slightly higher weight for more experienced jumpers, and expands the Not Recommended range for less experienced jumpers, making experience level slightly more important.) As for line trim charts: I looked mainly at the 143 model. (PDR revision E is current, OP revision A is current) Sliders are the same size for the 143, but a little bigger on smaller Optimums because their slider stays the same while the PDR's gets smaller. For big sizes, all are the same, keeping the same slider size as the 143. For the 143's, the A lines lengths are the same, as are additional B, C, and D distances. This suggests the attachment point geometry is likely the same too (same distances along the chord). For the 143's, the distance from the A's to the brake line attachments goes down 3.75" -- in effect adding more breaks. For the 143's, the lower steering line (above the eye) becomes shorter on the OP basically by the amount to make up the difference seen above (within a quarter inch)(and suggesting the cascades didn't change). For the 143's, the brake eye to toggle length goes up a whole 6". So some of that goes into making up for the shorter distance above the brake eye, and there's an extra couple inches of slack in there too. Maybe that helps the modern jumpers a little, those who expect the flare power lower in the flare stroke, but it really isn't much in that regard. The 99's are like the 143's: Zero change in trims, only some changes in brake line. Things can be different at different sizes though. Looking quickly at the 253's, there the basic trims are not the same, the PDR and OP have pretty much all numbers changed by up to 2". Just about everything was tweaked or revised. (One apparent large change is the LST shrinking by 11" or so, but brake cascades must be lengthened nearly as much, as the position of the tail relative to the A's is only slightly changed at about an inch shorter.) Brake to toggle length goes up even more, this time about 7", and that's with little change in the tail's position with brakes set, and probably not much in the general geometry, so a lot of slack is added. ===== For the 143's, with A,B,C,D trims the same on the same planform, that suggests the trim angle is the same too. I would have guessed the trim would be steeper for example, in order to give the Optimum more speed for an easier flare with more of a time window. But that's not the case! Indeed PD says the Optimums have a slightly shallower glide than PD-R's. (Technically one could change the trim angle if all the B,C,D trim points shifted along the chord, but that scenario seems unlikely, with actual trim values maintained exactly.) So where do the differences in the PD-R and Optimum opening characteristics come? For the 143's or 99's, so little has changed so that it comes down to only the deeper brake settings, or the fabric. Well, sail vs. ZP vs. F-111 does affect openings, so maybe the low bulk fabric behaves differently too when flapping around and subject to high pressures (even if it meets or exceeds F-111 style permeability in normal tests). Similarly, how about the landing characteristics? PD says the Optimum has a longer control range and even better flare. Does it actually stall slower or just have a longer stroke that changes the feel? Does the slightly lower angle of descent make it easier even though diving more for the ground would usually gives a canopy a better flare by giving energy for the flare? So with some things not changed at all, but some tweaking, plus the fabric change, it is hard to tell where the changes in opening and landing characteristics come from, at least from this analysis. [Edit:Or is there a change in the airfoil?] There's some PD / LeBlanc magic still in there... Quote Share this post Link to post Share on other sites
pchapman 279 #30 February 12, 2015 hackish A flare is not subjective at all. I'll disagree. Maybe we aren't really arguing because we're using the term in different ways. Of course everything can be calculated down to numbers, whether stall speed, control forces, etc. But then nothing in the universe is subjective because it's all just physics. But flare IS very subjective because there's a person controlling it. Changes to where the flare power occurs, and total flare length, and pressures, will affect how people land something, especially if they are not used to that particular combination of controls. A quantitative characteristic in a vehicle (parachute, airplane, motorcycle) such as those for a very light and short control stroke for a given output, will have a strong subjective component when humans are involved as the controllers. A vehicle like that might be seen as very good/bad/responsive/twitchy/uncontrollable, depending on the design and the user. Quote Share this post Link to post Share on other sites
mxk 1 #31 February 12, 2015 Mark Procos from UPT talks a little bit about PDR vs OP differences in the following video. I actually recommend watching the whole thing along with the other videos from BPA 2015. https://www.youtube.com/watch?v=1khn7DY9OPk&feature=player_detailpage&list=PLMqCekDhfSja0GAZnz34dY2cyYZQNQFEb#t=1249 Quote Share this post Link to post Share on other sites
stayhigh 2 #32 February 12, 2015 Longer break lines? Standard velo comes with the break line that so short that it is basically un-usable for me as it stalls at my chest level somewhere. Same velo, you can lengthen it and have it to have longer flare stroke. Same canopy, different length. So are you saying that same canopy(velo) went from less of a flair power to more of a flair power? Flair itself is not a subjective thing, however if one to say that "it has powerful flair vs weaker flair",,,,, I want to ask what defines powerful flair?? Wether the flair is powerful or not, that is subjective and it is a pure marketing slang. What defines "powerful flair"? Tell me a example of weak flair. This thread has gone to pissing match again. That's how things are at dz.com All I know for sure is that, if I have to pack it, I much rather pack OP vs PDR. If I have to land it, I much rather choose OP over PDR. Just don't give me Micro-Raven 109. Bernie Sanders for President 2016 Quote Share this post Link to post Share on other sites
theplummeter 15 #33 February 13, 2015 If one canopy can carry more weight at a lower speed or more weight at the same speed without stalling, that canopy has a better flare. Where that flare occurs in the toggle stroke is subjective but irrelevant to how much lift an airfoil can produce at a given speed. Quote Share this post Link to post Share on other sites
Quagmirian 40 #34 February 13, 2015 pchapmanSo with some things not changed at all, but some tweaking, plus the fabric change, it is hard to tell where the changes in opening and landing characteristics come from, at least from this analysis. [Edit:Or is there a change in the airfoil?] There's some PD / LeBlanc magic still in there...Optimum has a pretty pronounced nose lip. The V tapes are distributed differently. I haven't had a good look at one yet, but I assume there are subtle panel shape differences too. PD has had 25 years to come up with improvements, after all. It's not magic, these little things will add up. Quote Share this post Link to post Share on other sites
Skydivesg 7 #35 March 2, 2015 Quagmirian***The canopy is not just a PDR with low bulk material. It's a completely different plan form.I'm pretty sure the planform is exactly the same. It'll be other things they've changed like line trim, airfoil/panel shape etc. Nope. Everything is different. Airfoil, planform, aspect ratio, fabric, line trim… This is based on many conversations with the PD R&D design team.Be the canopy pilot you want that other guy to be. Quote Share this post Link to post Share on other sites
Quagmirian 40 #36 March 2, 2015 Skydivesg...planform, aspect ratio...Gonna have to be pedant here. They must have the same planform since the aspect ratio is identical and they're both rectangular. Quote Share this post Link to post Share on other sites
DocPop 1 #37 March 2, 2015 Skydivesg planform, aspect ratio That is not borne out by PD's website which states that the aspect ratio is exactly the same."The ground does not care who you are. It will always be tougher than the human behind the controls." ~ CanuckInUSA Quote Share this post Link to post Share on other sites
mxk 1 #38 April 30, 2015 hackish*** Snivelly Optimum opening made a difference here (for worse...): https://www.youtube.com/watch?v=m1TMqJLk4U8 http://www.deepseed.com/d-spot/blog/liam/inside-no-pull-cypres-save-0 Without real data to show that they do open too slow it's really hard to say. PD has probably done more testing than all their competitors combined. The same PDR design has stayed in production so long because of careful design and extensive testing. The incident filmed isn't even a smoking gun against the optimum. How was it packed? Did the PC get a good launch? Is the exact cypres firing altitude known? In a single incident there are too many unknowns. You need a careful statistical analysis of multiple reserve openings to draw _ANY_ conclusion. Not 1, not 2. Dozens. Opening softer can simply mean the peak opening force is lower as the force is better distributed over the entire opening time. I've had a 800' snivel on my katana that ended in a bang. -Michael The recent Mirage Trap video shows multiple Optimum and PDR deployments. If you compare the Level Flight test (Optimum) with Right Spin (PDR), I think it's pretty clear that the Optimum takes about 200 ft extra to open in these low speed malfunction tests. Yes, still one or two non-identical examples, but at this point I think there are enough of those to make some valid inferences. Quote Share this post Link to post Share on other sites
achikin 0 #39 April 30, 2015 This is not a completely fair comparsion: PDR is opened in a violent spin while OP is opened in a stable position. Quote Share this post Link to post Share on other sites
