horizontal speed on tracking

[OSOK 0]

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I'm gonna do a few jumps tomorrow where I get out at the end of the load and track up jump run to see how much distance I can get.

Ok, I was staying out of it until now. Take this any which way, but for someone with a head as big as yours, you need to re-think certain things. I think instead of sounding like a badass, saying others dont track as well as you (with your jump numbers i seriously doubt you know what a good track even feels like), you should go back to square one and realize that tracking back up jump run is not safe.

Seriously, humble down a bit before it's too late.

There's NOTHING wrong with getting out last and then tracking UP jump run (not down), in the same direction the plane is travelling. And sorry to break it to ya, but I do have a good idea of what a good track feels like. Maybe not as much as the "experts" such as yourself, but good none the less. I don't think I'm a baddass. And anyway, how does tracking well make someone a baddass?

Why are you going to do that, ending up landing out? Do you think you have enouch experience to land out on purpose? I don't know what the area looks like, but then again, you should think. You can track perpendicular to jump run then do 180 and come back.

I'm not an expert, never said I was. Neither did you, but from your words it sounds like your head is bigger than it should be. This is all just words and you already give an air of "im the shit." I may be wrong, but if it's true, you should drop it right away. And seriously, with 54 jumps saying you've tracked with people not as good as you? I doubt it you can even tell if your track has wobbles all over it.

I'm sorry to go off topic. Delete if you'd like mods. Just thought someone needed to say something.

[PWScottIV 0]

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Nobody has sent me any protrack data... Just numbers that they remembered...

There's some learning going on in this thread!

Anyway, what the heck, here are a couple graphs to provide examples of the kind of tracks that people are talking about.

The "j1368" one is a straight track. RW suit, no booties, skinny jumper. Even in the reduced air density at altitude, true vertical airspeeds are consistently in the 76 to 82 mph range.

"j1544" is for another dive where I did a 180 turn which caused a spike in speed. It compares GPS output to Protrack data. (Raw protrack data reworked to provide a 3 second centered average rather than it's normal 6 second lagged average.)

Although there is some confusion during the turn, the GPS seems to confirm that the Protrack is not totally out of whack during long, steady state flight.

Of course I can't prove I didn't just spend all afternoon creating fake graphs. :)

OK, thanks a lot for posting those. As you can see in the attachment above, I was apparently able to get pretty slow (~74mph) as well, with no suit. I just didn't think that was possible, so I had discredited those numbers.

Gravity Waits for No One.

[PWScottIV 0]

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Why are you going to do that, ending up landing out? Do you think you have enouch experience to land out on purpose? I don't know what the area looks like, but then again, you should think. You can track perpendicular to jump run then do 180 and come back.

I'm not an expert, never said I was. Neither did you, but from your words it sounds like your head is bigger than it should be. This is all just words and you already give an air of "im the shit." I may be wrong, but if it's true, you should drop it right away. And seriously, with 54 jumps saying you've tracked with people not as good as you? I doubt it you can even tell if your track has wobbles all over it.

I'm sorry to go off topic. Delete if you'd like mods. Just thought someone needed to say something.

Yeah, I'm honestly NOT trying to come off like I know it all, because I know I have a LOT to learn... Hopefully I will ALWAYS have a lot to learn. It's not the first time someone has complained that they thought I was arrogant or cocky, so it's not shocking or anything... Nor is it something I strive for, sometimes I just happen to come off that way. Sorry.

As far as landing off, we have a riverbed that runs forever in each direction along our typical jumprun, so that is what I was planning to use to land on. I've tried tracking perpendicularly to the JR and I end up way too far away from the DZ when I do so, so that's why I'd like to do it the way I mentioned.

Gravity Waits for No One.

[OSOK 0]

Ok... I'm SO glad you didn't brush me off.

I'm a bit confused. Are your jump runs over the DZ? Forgive me, but I don't see how tracking away from the DZ can get you closer than tracking perpendicular to jump run.

[JohnMitchell 14]

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With all due respect, you have no idea what you are writing about.

PS both Darkwing and I are physics professors, Billvon is a professional engineer.

You left out "And Johnmitchell is damn smart."

[JohnMitchell 14]

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Ok, well I just didn't think it was possible to slow down to that speed... Here's a max track I did on jump 29. I was working on transitions from sit to belly to back flying during the jump and then I did my track at the end like i usually do. I apparently got down to 74mph... I have several other jumps where I got down to mid 70s too.

So now are you going to apologize to us?

Keep an open mind in this sport. You'll progress faster.

[PWScottIV 0]

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Forgive me, but I don't see how tracking away from the DZ can get you closer than tracking perpendicular to jump run.

Yeah, if I track perpendicularly I end up going way over the airport, or the other way I end up going way past high-voltage powerlines, both of which are obstacles that I'd rather not play with. I can handle a landing and a potentially long hike on a sandy riverbed. I'll do the jumps tomorrow and see what my results are.

Gravity Waits for No One.

[OSOK 0]

I'm lost. Are your jump runs the same direction, no matter what the winds are doing?

[PWScottIV 0]

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Ok, well I just didn't think it was possible to slow down to that speed... Here's a max track I did on jump 29. I was working on transitions from sit to belly to back flying during the jump and then I did my track at the end like i usually do. I apparently got down to 74mph... I have several other jumps where I got down to mid 70s too.

So now are you going to apologize to us?

Keep an open mind in this sport. You'll progress faster.

Questioning things you don't understand is the best way to learn about them... They used to ridicule and even execute people for saying that the earth wasn't the center of the universe and that the earth isn't flat... Who wasn't open minded then?... The people who thought they already knew it all.
I NEVER professed to know it all, I only questioned what some people had stated as being true without any science to back it up beyond "I once had a jump that showed such and such, but I don't have the data to support that claim anymore". How do you think things get discovered in this world?

Your recommendation of keeping an open mind is a very good one... Because that is how science thrives. I honestly have yet to see any data that is good enough for me to fully make my mind up... I'd like to see a jump where someone has combined the data from GPS and Logging altimeter to determine if they closely support one another, or prove that there is significant error. I'm still very skeptical about the accuracy of logging altimeters. Due to the way they are measuring/calculating your decent rate while in freefall, it seems that it would be very easy to affect the reading by either placing it in high-velocity airflow or in burble. Does anyone have any such data that we could compare from a tracking jump?

Gravity Waits for No One.

[PWScottIV 0]

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I'm lost. Are your jump runs the same direction, no matter what the winds are doing?

No, but the wind is almost always coming from the same direction (approximately along the riverbed).

Gravity Waits for No One.

[cpoxon 0]

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Ok, well I just didn't think it was possible to slow down to that speed... Here's a max track I did on jump 29. I was working on transitions from sit to belly to back flying during the jump and then I did my track at the end like i usually do. I apparently got down to 74mph... I have several other jumps where I got down to mid 70s too.

You yourself said

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Digital logging altimeters show speeds that slow sometimes, but it's only due to fluctuations in air pressure caused by variable airflow and burble around the unit.

and I think this is the case in the graph that you posted. Your 74 mph is defintely a spike since it is a single point with much higher speeds around it, much like those people who think they can go really fast when they have a peak over 200 mph on their ProTrack. It really needs to be a sustained trend such as the plots that Peter and I posted before I would be happy claiming achieving speeds of 74 mph.

Skydiving Fatalities - Cease not to learn 'til thou cease to live

[PWScottIV 0]

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...and I think this is the case in the graph that you posted. Your 74 mph is defintely a spike since it is a single point with much higher speeds around it, much like those people who think they can go really fast when they have a peak over 200 mph on their ProTrack. It really needs to be a sustained trend such as the plots that Peter and I posted before I would be happy claiming achieving speeds of 74 mph.

I totally agree... I was just seeing how many people who might blindly buy into my claim... Which is very likely not my actual speed, but more likely a glitch from decelerating very fast. It's easy to just blindly trust data from a graph, and many people do... It takes a lot more to actually make sure the data is accurate. That's why I'd like to compare data from at least two separate devices, like a GPS and a logging alti at the same time.

Gravity Waits for No One.

[cpoxon 0]

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...and I think this is the case in the graph that you posted. Your 74 mph is defintely a spike since it is a single point with much higher speeds around it, much like those people who think they can go really fast when they have a peak over 200 mph on their ProTrack. It really needs to be a sustained trend such as the plots that Peter and I posted before I would be happy claiming achieving speeds of 74 mph.

I totally agree... I was just seeing how many people who might blindly buy into my claim...

Some might call that a troll, which can get you in trouble around here!

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Which is very likely not my actual speed, but more likely a glitch from decelerating very fast. It's easy to just blindly trust data from a graph, and many people do... It takes a lot more to actually make sure the data is accurate. That's why I'd like to compare data from at least two separate devices, like a GPS and a logging alti at the same time.

Me too. Paralog combines the two lots of data quite nicely, however I've never got around to doing it because my eTrex is a bit cumbersome compared with the Forerunner style GPS units around these days. But it's certainly piqued my interest again.

Skydiving Fatalities - Cease not to learn 'til thou cease to live

[PWScottIV 0]

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Some might call that a troll, which can get you in trouble around here!

I had already stated my belief that logging altimeters can give erroneous results. It was interesting to see how easy is was for some to just glance at it and automatically agree without examining what might be happening. I didn't doctor the data or anything. And I wasn't going to let it go forever without questioning people about how valid they thought the graph was.

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Me too. Paralog combines the two lots of data quite nicely, however I've never got around to doing it because my eTrex is a bit cumbersome compared with the Forerunner style GPS units around these days. But it's certainly piqued my interest again.

I'm sorta surprised that nobody REQUIRES that for competitions. Are you gonna try it?

Gravity Waits for No One.

[jakee 1,257]

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I'm sorta surprised that nobody REQUIRES that for competitions. Are you gonna try it?

What competitions? Speed skydiving averages two ProTracks mounted in clean air on the hip. TrackingDerby uses GPS results, the wingsuit comps at Stupino last year used GPS results. Most Ad Hoc local tracking comps that I've heard about either use GPS or a visual measure of who went furthest to determine the winners.

And as Craig has pointed out, it is well known that loggers like the ProTrack can give erroneous 'point data,' unrealistic spikes in speed resulting from moving the unit from a high to low pressure (or vice verca) area by, say turning your head. I've never heard of data loggers being significantly wrong in presenting sustained speeds though.

The graph Craig showed clearly demonstrated areas of sustained speeds, with only small fluctuations, that fit in consistently with the rest of the data.

Do you want to have an ideagasm?

[kallend 1,635]

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With all due respect, you have no idea what you are writing about.

PS both Darkwing and I are physics professors, Billvon is a professional engineer.

You left out "And Johnmitchell is damn smart."

And the person who posts as Johnmitchell, whom I have not actually met, is damn smart.

...

The only sure way to survive a canopy collision is not to have one.

[JohnMitchell 14]

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Questioning things you don't understand is the best way to learn about them... They used to ridicule and even execute people for saying that the earth wasn't the center of the universe and that the earth isn't flat... Who wasn't open minded then?... The people who thought they already knew it all.
I NEVER professed to know it all, I only questioned what some people had stated as being true without any science to back it up beyond "I once had a jump that showed such and such, but I don't have the data to support that claim anymore". How do you think things get discovered in this world?

Your recommendation of keeping an open mind is a very good one... Because that is how science thrives. I honestly have yet to see any data that is good enough for me to fully make my mind up...

Some people ridicule people who say you can slow down your rate of descent in a good track by creating lift. They repeatedly say it's impossible. Wouldn't scientific inquiry demand that you examine the available evidence, some of it casual observation, such as my tracking dive where I was at 6000' when the group I left with was deploying at 2500? Some harder data would be Kallend's 90 second "trackfall" from 13,500. Then others offered their graphed data for your perusal. Ask how these things are happening. Question what mechanism may be at work. I feel you're the one who may be looking back at the flat earth, refusing to ask questions about retrograde motion.

Reference the F-18 and high alpha? Here's a pic of the vortices at work, smoke added for emphasis. Now we need get this shot with a tracking human.

http://www.nasa.gov/centers/dryden/news/FactSheets/FS-002-DFRC.html

Edited to make clicky - Craig