SkydiveMonkey 0 #1 February 15, 2003 Most of the ones I have seem normal, but this seems a little weird. It's helmet mounted, but it shouldn't make THAT much difference surely? I'm quite sure I didn't fall at 80 mph (speed goes up when I tracked off, but I normally track quite flat, not diving).____________________ Say no to subliminal messages Quote Share this post Link to post Share on other sites
Casch 0 #2 February 16, 2003 I don't know what to say...that seems really strange...did you rip ass in a sit? That may have done it... Quote Share this post Link to post Share on other sites
ernokaikkonen 0 #3 February 16, 2003 So what kind of jump was that? Quote Share this post Link to post Share on other sites
SkydiveMonkey 0 #4 February 16, 2003 That was a FS () dive - 2 way I think. ____________________ Say no to subliminal messages Quote Share this post Link to post Share on other sites
kallend 1,648 #5 February 16, 2003 QuoteMost of the ones I have seem normal, but this seems a little weird. It's helmet mounted, but it shouldn't make THAT much difference surely? I'm quite sure I didn't fall at 80 mph (speed goes up when I tracked off, but I normally track quite flat, not diving). I get a lot that look like that, but I know my track has a low fall rate because my freefall times can go over 80 seconds from 13,000ft on a tracking dive (and the Protrak measures time much more accurately than speed). I put it down to the funny airflow during a track. I get more "normal" graphs with the Protrak on my ankle. Unfortunately I don't have ears on my ankle so I don't put it there too much.... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites
Staso 0 #6 February 16, 2003 QuoteMost of the ones I have seem normal, but this seems a little weird. It's helmet mounted, but it shouldn't make THAT much difference surely? I'm quite sure I didn't fall at 80 mph (speed goes up when I tracked off, but I normally track quite flat, not diving). looks like you turned you head the way your protrack faced up first and it got into your shadow. sudden change of preassure resulted in slow speed spike. then you turned your head the other way around and preassure changed from low to high around protrack - high speed spike. when mounted inside of helmet, protrack is very sensetive to head movements. stan. -- it's not about defying gravity; it's how hard you can abuse it. speed skydiving it is ... Speed Skydiving Forum Quote Share this post Link to post Share on other sites
SkydiveMonkey 0 #7 February 16, 2003 It still shouldn't have made that much difference over that period of time though?____________________ Say no to subliminal messages Quote Share this post Link to post Share on other sites
Staso 0 #8 February 16, 2003 QuoteIt still shouldn't have made that much difference over that period of time though? i think it could. i've been doing speed dives and saw some odd profiles. they disappeared after i moved my protrack to my harness. for speed skydiving protrack used to be mounted on the ankle and there were speed pikes registered up to 600 mph due to leg kicking. after that all the records were retired and protrack was moved to harness. stan. -- it's not about defying gravity; it's how hard you can abuse it. speed skydiving it is ... Speed Skydiving Forum Quote Share this post Link to post Share on other sites
SkydiveMonkey 0 #9 February 16, 2003 Where on the harness do you have it, and how is it mounted?____________________ Say no to subliminal messages Quote Share this post Link to post Share on other sites
Staso 0 #10 February 16, 2003 QuoteWhere on the harness do you have it, and how is it mounted? side lateral webbing. i have a protrack cradle sewed to the webbing and i also use elastics to be safe. i don't wanna lose it :) stan. -- it's not about defying gravity; it's how hard you can abuse it. speed skydiving it is ... Speed Skydiving Forum Quote Share this post Link to post Share on other sites
masher 1 #11 February 17, 2003 Have you got any pics?-- Arching is overrated - Marlies Quote Share this post Link to post Share on other sites
Staso 0 #12 February 17, 2003 QuoteHave you got any pics? which ones ? speed dives, protrack graphs ? stan. -- it's not about defying gravity; it's how hard you can abuse it. speed skydiving it is ... Speed Skydiving Forum Quote Share this post Link to post Share on other sites
masher 1 #13 February 17, 2003 actually, of your protrack holder...-- Arching is overrated - Marlies Quote Share this post Link to post Share on other sites
Staso 0 #14 February 17, 2003 Quoteactually, of your protrack holder... no, no really. you can look at speedskydiving.net and there were couple of pics where you can see it. stan -- it's not about defying gravity; it's how hard you can abuse it. speed skydiving it is ... Speed Skydiving Forum Quote Share this post Link to post Share on other sites
cpoxon 0 #15 February 19, 2003 I'd like to draw your attention to this post I made and in particular to this graph which plots a helmet mounted ProTrack against two laterally mounted ProTracks for the during the same wingsuit jump. As you can see, the variation is wide, probably due to movement of the head (looking left and right) and moving the ProTrack into and out of differently pressured air. I've just noticed that the time period between the peaks and the troughs is approximately 6 seconds and it's approximately the same on your graph. Six seconds is the period of time that a ProTrack buffers and averages freefall profile data over. I wonder if it is a coincidence? Quote Share this post Link to post Share on other sites
dreamsville 0 #16 February 21, 2003 I think that analysis is correct. The extremities are normally the best place for the ProTrack, preferably with it on the outside. I wore mine on my ankle until the Skytronic audible broke, and then I had to move the ProTrack to the helmet (still look at the ground and the wrist unit though, let's never forget). Orientation of a cavity containing the ProTrack can cause distorting pressure changes. I had a graph on one free-fly jump that looked like the one in the attachment, more or less, after I made the shift in unit location. |I don't drink during the day, so I don't know what it is about this airline. I keep falling out the door of the plane. Harry, FB #4143 Quote Share this post Link to post Share on other sites
