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The common definition of AoA taught during private pilot training is that it's the angle between relative wind and the chord line, with the latter defined as a straight line from the leading to the trailing edge of the wing. The would include flaps, ailerons, and any other movable surfaces. During my aerobatic training, I was introduced to another definition of AoA as the angle between relative wind and the zero-lift line of the wing. Some wing shapes continue to generate lift at negative AoA with respect to the chord line because the chord is just a useful approximation of the wing's overall shape. The zero-lift line is the sum total of all aspects of the wing, which again would include any movable surfaces. You can find the zero-lift line by putting the plane into a vertical climb until it has no horizontal movement. Way more technical information here: http://www.av8n.com/how/htm/aoa.html

I completely understand your position, and I'm actually glad that you've not gone down the software patent road on this. However, it does leave you the problem of proving that your AAD is better in some ways than the current generation, and that it does not introduce many (any, ideally) new failure modes. SL tests aren't going to be sufficient for this. It's a different and more controlled environment. I'm not familiar with trade secret law, but have you considered doing an independent code audit protected by NDAs? On the software side, the question I'm most interested in is whether the system is based on a machine-learning classifier algorithm or if the core situation identification logic is coded by hand. Would it correctly identify the exit for all involved in the event of a mid-air collision? What about an accidental main deployment while setting up in the door? Based on what you said about having a pool of gold standard data, I doubt that you have good representations of these two and many other rare situations. How do you know that your AAD will do the "Right Thing" in scenarios that haven't been recorded and simulated? What happens if the system gets confused by unfamiliar, corrupt, or missing sensor data?

I really hope that these get recorded and uploaded to YouTube/Vimeo. For me, this will come down to whether I understand how the device works and how it can fail. Even though I haven't seen the source code for my Vigil, I have a sufficiently good idea of how it does what it claims to do. Your claims are far more ambitious, which means more complex implementation, and more room for bugs and unforeseen failure scenarios. Once your AAD has been out for 10+ years without any major problems, then you could probably get away with saying "trust me." For a brand new device, however, if I can't understand how it solves the very difficult problem of translating sensor data into an accurate representation of the current situation, it will be hard for me to trust it.

As I posted in that thread, I'm pretty sure that it was a Skyhook deployment, but I agree that the size of the reserve was the actual problem:

I have a Quattro set to 6k, 5k, 4k, and 2k. Canopy mode alarms are 1.5k, 1k, and 0.5k. A lot of people reconfigure their audible depending on the jump they are doing and also set alarms to altitudes where they need to do something, such as turn and track. I don't like doing either of these things. Seen way too many people do the wrong thing at the wrong time because they forgot to change their audible settings. An audible is there to improve situational awareness. My settings are the same whether I'm doing belly jumps or wingsuiting. 6k, 5k, and 4k alarms give me a nice even countdown toward the end of the jump. The 2k alarm is one that I don't expect to hear under normal circumstances, but it's useful in an emergency, so I think having 4 alarms total is not a bad idea. Same theory with my canopy alarms. Three beeps evenly spaced to give me a better sense of time and progress. You don't need to be doing HP landings to benefit from this. They just allow you to be more consistent, which will be helpful when you start working on your accuracy for the C license.

Has anyone measured the difference between the pull force at the pin vs. at the handle with a steel ripcord on the Vector? With Spectra (post-PSB yellow label), the difference is 8-10 lbs. On my rig, it usually takes around 10 lbs to move the pin directly, and just under 20 lbs to pull the handle. I'm curious how this compares to a steel ripcord. My previous Spectra ripcord, which I replaced even though it wasn't covered by the PSB, added 23.2 lbs (10.5 at the pin, 33.7 at the handle). Reported this to UPT, but nothing came out of that discussion.

Previous thread: http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=4817662

Your theorem makes no sense if given the same time and distance traveled in both scenarios. The sniveling canopy would have to make up time and distance in the second stage of the opening to equal the other canopy. The result to equal the other would be a faster, harder deceleration at the bottom end. MEL Not that it matters given that the OPT probably does take a bit more time and distance to open, but draw a speed vs. time plot with two points representing the start of deployment (e.g. t=0, speed=120) and end of deployment (e.g. t=3, speed=12). A straight line between those two points is the optimal deceleration profile with the lowest possible peak force. The area under that line is distance traveled. Now draw a curve between the same two points that starts above the straight line and crosses it in the middle. You can draw it such that it has the same area (i.e. distance) and time, but higher deceleration in the middle of deployment. Or you can have higher deceleration initially, flat middle, and another jolt at the end. Infinite possibilities. In other words, if you can spread out the deceleration more evenly over time, you can certainly have a canopy that opens softer in the same time and distance. You were assuming that it's the OPT with the suboptimal profile.

Here's what Mark Procos from UPT had to say on the topic: BPA Skydive the Expo 2015 - Equipment Compatibility with Mark Procos Softer openings was one of the design goals for the OPT. That means covering longer distance, which may make it less safe than a PDR under specific circumstances (where many other variables and decisions come into play). On the other hand, it may be safer than a PDR at higher speeds or in situations where canopy size is a factor. I have not seen sufficient evidence to conclude that the OPT is inherently less safe than the PDR, but I do have my Vigil set to 1,250 ft to account for the longer snivel.

I don't see any lines not going through a slider grommet: [inline slider1.jpg] Also, the slider does come all the way down to the front risers for a brief moment: [inline slider2.jpg]

Not only that, 401s are just plain cool. I was refurbishing them and selling them on ebay a couple years ago. They are the most advanced domestic machine Singer ever made. They are precise and intricate and a pleasure to work on. I still have about 5 of them waiting for me to get around to shining them up. Do you have a recommendation for what type of lubricant to use for the metal gears and the motor worm gear? The Singer lubricant that's still available seems pretty low quality.

These tests don't really make sense to me. The manufacturers provided containers with optimally sized reserves, and all deployments were in the optimal body position with the reserve pulled straight up and out of the container. This same test would have been performed by each manufacturer thousands of times already, so it's not exactly surprising that no problems were found. Am I missing some crucial detail here? Primary Root Cause D test wasn't done, so you have no idea what the maximum bag extraction force is for each container. That's the number that needed to be compared with the minimum sustained subterminal PC force. As it stands, the tests show that all of these containers are able to deploy their reserves under very specific (pretty much ideal) conditions.

I've re-centered the needle and adjusted the position finger on my 401A to accommodate a size 19 needle. It handles E thread just fine.

My answer to THAT is: There are those around the world that uses the metric system. Then there is the one country that has put man on the moon without it. Yep, and a Mars Climate Orb... On, no, wait... Not that one.

See this: http://www.edmundoptics.com/resources/application-notes/imaging/advantages-of-telecentricity/ A photograph without any special lenses or post-processing will not give you an accurate 2D representation of the rib shape. Why not do this with a protractor and a ruler?

I don't know of any FAR or USPA BSR that address' intentional cutaways. I done several TSO that require you to cutaway and I always wore a separate harness and reaserve. But even in the test standards (PIA-135) wearing a second reserve is not mentioned. Could you post where you saw this? Thanks I learn something new everyday. I was told early in my skydiving career that a third auxiliary parachute was required for intentional cutaways, but after being unable to find anything in the regs I asked Jump Crouch, Director of Safety & Training at HQ for his input. He also did some homework to be sure he gave me the right answer and confirmed that there is nothing in writing that requires it. Sooooo....chop away! It can probably be argued either way. A reserve is defined as "an approved parachute worn for emergency use to be activated only upon failure of the main parachute or in any other emergency where use of the main parachute is impractical or use of the main parachute would increase risk." If you're intending to use your reserve, then you might need another one to satisfy that definition for 105.43 ("No person may conduct a parachute operation using a single-harness, dual-parachute system... unless that system has at least one main parachute, one approved reserve parachute..."). Where did you get that quote? If it's FAA documentation that changes the entire argument. 105.3 Definitions

I don't know of any FAR or USPA BSR that address' intentional cutaways. I done several TSO that require you to cutaway and I always wore a separate harness and reaserve. But even in the test standards (PIA-135) wearing a second reserve is not mentioned. Could you post where you saw this? Thanks I learn something new everyday. I was told early in my skydiving career that a third auxiliary parachute was required for intentional cutaways, but after being unable to find anything in the regs I asked Jump Crouch, Director of Safety & Training at HQ for his input. He also did some homework to be sure he gave me the right answer and confirmed that there is nothing in writing that requires it. Sooooo....chop away! It can probably be argued either way. A reserve is defined as "an approved parachute worn for emergency use to be activated only upon failure of the main parachute or in any other emergency where use of the main parachute is impractical or use of the main parachute would increase risk." If you're intending to use your reserve, then you might need another one to satisfy that definition for 105.43 ("No person may conduct a parachute operation using a single-harness, dual-parachute system... unless that system has at least one main parachute, one approved reserve parachute...").

I'm guessing that this falls under the "personnel-carrying U.S. military parachute" part of the approved parachute definition: Sounds like it would still need to have some sort of identification though.

I had a very similar thing happen a few weeks ago. The pilot chute got wrapped when the canopy surged forward toward the end of inflation. Followed the exact same steps as you; no problems on landing. As long as the pilot chute is collapsed and not distorting the canopy (i.e. there is slack in the bridle), I don't think it would cause any serious harm.

Personally, I would start by cloning an existing rib shape just to see how closely your canopy ends up matching the original. I imagine that there are plenty of places for errors, so cloning a known shape will tell you what adjustments are needed to have the plan match the finished product. After that, I would look at something like OpenFOAM to actually model the airfoil and explore the effects that various changes have on its performance. Though as Lee said, I'm guessing that correlation between a computer model and the real thing will not be that great. There are also some non-free options like MultiElement Airfoils.

I'm guessing that it's based simply on your rate of descent with a different threshold for each jump type. I don't think there any correction in there. The number is closer to the inflation altitude than pilot chute deployment.

I have BH Rev2. It was my first helmet after AFF and I'm still very happy with it two years and ~350 jumps later. Aero wasn't out when I was researching which helmet to buy, but even if it was, I would still get the Rev2 because I can put it on and take it off without removing my glasses. I put a camera on it about a month ago using BH's Swivel Mount. It's a good snag-resistant design, but does add a bit of weight to the visor. The cutaway system will release the chinstrap, but I have serious doubts that it would unlock the visor if there is any amount of tension on it. Unlike a 3-ring system, there is no force reduction on the cable, and it goes past a wide carbon fiber opening and through a nylon tape, both of which will create a lot of friction when you try to pull it. I decided that the cutaway handle was actually a bigger snag hazard and could potentially release the chinstrap at a bad time, taking the helmet and my glasses off. I got rid of the handle and rerouted the cable so that it's not exposed in any way. The chinstrap release can be operated with one finger. The same goes for the visor, which I think is a better design than having to use both hands. In terms of safety, I think that all skydiving helmets fall into the "better than nothing" category. BH is carbon fiber, but I don't know whether that will have any significant advantage over plastic in any serious head impact. Fogging has not been an issue. Before I had a camera, I would open the visor under the canopy, but now I leave it closed until the landing. Bingo! And it's not just helmets. I tried wearing the G3, Z1, and Phantom XV before settling on the Rev2. The Rev2 had better visibility and was also the only one that was comfortable for me. I needed the XXL version and the largest versions of the other helmets were still too small for me.

What problem are you trying to solve?

I don't see any such requirement for riggers. 61.3(a) for pilots, yes. 65.111(d): Each person who holds a parachute rigger certificate shall present it for inspection upon the request of the Administrator or an authorized representative of the National Transportation Safety Board, or of any Federal, State, or local law enforcement officer. Doesn't apply to just anybody asking, though I think it's a reasonable thing for a rigger to do if a customer does ask. For pilots it's 61.3(l), which is basically the same, but also applies to the TSA.

I'd say that's more of an inherent problem with the platform that you are choosing for your communications rather than who you let into the group. If you were to set up an open mailing list either on Google Groups or with GNU Mailman, the quality of discussion would almost certainly be higher. As an added benefit, you'd actually be able to go back and search the archives many years from now when Facebook has gone the way of Myspace.