Tracking and fall rate question.

[OSOK 0]

I've searched around for this but couldn't find it. If it's been asked before, forgive me.

Ok. I'm going to try to explain this as much as I can.
I understand people can get some pretty small numbers when it comes to fall rates while tracking. If someone gets an average speed of 90s or so... is that an attainable speed of someone just flying as flat on his belly as possible?

Basically what I'm asking is what's the slowest fall rate one can achieve on belly? I'd like to know the line where the only way to get a slow enough fall rate is by gaining extra lift from forward motion.

Thanks!

[JohnMitchell 16]

No matter how slowly a person can fall straight down, they can fall even slower in a really good track. My wife, 5'5", 105 pounds, can probably stay up with the best of them. Don't know how slow that is ~90mph?

[mnealtx 0]

I don't think you're going to be able to find any "magic number". There's too many variables from person to person... body position, jumpsuit, whether they're a fast or slow faller, etc...

My "normal" fall rate is in the 120-130 range, depending on jumpsuit, body position, etc... but I've hit a recorded 98mph doing vertical motion drills while I was working toward my "A", and I'm 5'11" and 225 lbs exit weight...

Mike
I love you, Shannon and Jim.
POPS 9708 , SCR 14706

[gemini 0]

I agree that there are two many variables to give a general answer to this question. I wheigh 175 or 195 out the door and have a relaxed slow fall rate of 111-104. In a hard track I can slow to 83 vertical.

Blue skies,

Jim

[OSOK 0]

Hmm. When people track from big way RWs... do they use any kind of specific track? Is flat-tracking what is used for tracking competitions and such? Or is it just a matter of achieving the best horizontal-to-vertical ratio?

[kallend 2,131]

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Hmm. When people track from big way RWs... do they use any kind of specific track? Is flat-tracking what is used for tracking competitions and such? Or is it just a matter of achieving the best horizontal-to-vertical ratio?

Unless instructed to the contrary, I track as hard (flat) as I can on breakoff from bigways.

I've averaged 103 on my belly, on one of Roger Ponce's bigways. My best tracking speed was 79mph average (in a slick 4-way suit).

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

[darkwing 5]

There have been many threads about tracking, and often (always?) they end up being discussions about descent rate, which I think is a grave mis-application of some numbers. Does descent rate equate to horizontal separation? I think not. I'd like someone to present some arguments though. Until then, stop the talk about descent rate as evidence for an effective track.

I have watched a fair number of medium to big-ways, and from the ground viewer's perspective there is a very wide range of "horizontal effectiveness" (for lack of a better phrase) on any load. I bet everyone thinks they are pretty good trackers though.

-- Jeff
My Skydiving History

[kallend 2,131]

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There have been many threads about tracking, and often (always?) they end up being discussions about descent rate, which I think is a grave mis-application of some numbers. Does descent rate equate to horizontal separation? I think not. I'd like someone to present some arguments though. Until then, stop the talk about descent rate as evidence for an effective track.

I have watched a fair number of medium to big-ways, and from the ground viewer's perspective there is a very wide range of "horizontal effectiveness" (for lack of a better phrase) on any load. I bet everyone thinks they are pretty good trackers though.

The difference between descent rate in a track and when falling vertically is due to lift generated from the airflow over your body, and that in turn depends on forward speed. To get a slow descent rate in a track requires that you have good body position and adequate forward speed.

Whether slowest vertical speed corresponds with with best L/D is unlikely, of course, but I'd bet it's fairly close.

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

[Costyn 1]

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The difference between descent rate in a track and when falling vertically is due to lift generated from the airflow over your body, and that in turn depends on forward speed. To get a slow descent rate in a track requires that you have good body position and adequate forward speed.

Whether slowest vertical speed corresponds with with best L/D is unlikely, of course, but I'd bet it's fairly close.

This is true, however, in a wingsuit you can get more forward speed with more vertical speed, and thus increasing your distance (separation). On the other hand, when you fly flatter, you will get a lower vertical speed, but the forward speed won't be as much. This article explains it better: http://www.phoenix-fly.com/articles%20stvari/performance_flying_1.pdf (see the pictures on page 2). What I'm trying to say is that a lower vertical speed won't necessarily equate to more horizontal speed.

To get to my point, I'm wondering if the same thing is true for tracking. Atmonauti dives can cover a lot of horizontal distance, although the angle is a lot steeper compared to a hard flat track. The vertical speed is higher in atmonauti, but so is the horizontal speed (but the jump doesn't last as long and someone in tracking and atmonauti will probably end up in the same place). I don't have any GPS graphs (yet) to back this up, but maybe someone with more atmonauti experience can chime in.

Cheers,

Costyn.

Costyn van Dongen - http://www.flylikebrick.com/ - World Wide Wingsuit News

[JohnMitchell 16]

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Whether slowest vertical speed corresponds with with best L/D is unlikely, of course, but I'd bet it's fairly close.

Bingo. Look in an aircraft manual. The glide speeds for lowest rate of descent and best glide angle are close, but slightly different. Efficient is efficient.

[kallend 2,131]

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The difference between descent rate in a track and when falling vertically is due to lift generated from the airflow over your body, and that in turn depends on forward speed. To get a slow descent rate in a track requires that you have good body position and adequate forward speed.

Whether slowest vertical speed corresponds with with best L/D is unlikely, of course, but I'd bet it's fairly close.

This is true, however, in a wingsuit you can get more forward speed with more vertical speed, and thus increasing your distance (separation). On the other hand, when you fly flatter, you will get a lower vertical speed, but the forward speed won't be as much. This article explains it better: http://www.phoenix-fly.com/articles%20stvari/performance_flying_1.pdf (see the pictures on page 2). What I'm trying to say is that a lower vertical speed won't necessarily equate to more horizontal speed.

To get to my point, I'm wondering if the same thing is true for tracking. Atmonauti dives can cover a lot of horizontal distance, although the angle is a lot steeper compared to a hard flat track. The vertical speed is higher in atmonauti, but so is the horizontal speed (but the jump doesn't last as long and someone in tracking and atmonauti will probably end up in the same place). I don't have any GPS graphs (yet) to back this up, but maybe someone with more atmonauti experience can chime in.

Cheers,

Costyn.

I don't think the wingsuit analogy is valid - when tracking you can't really achieve the position used for maximum duration in a WS, and if you could, you don't have the surface area to give a slow descent rate anyway.

It would be interesting to compare atmonauti with flat tracking. Really needs to be the same individual in the same suit for a valid comparison.

...

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

[Costyn 1]

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I don't think the wingsuit analogy is valid - when tracking you can't really achieve the position used for maximum duration in a WS, and if you could, you don't have the surface area to give a slow descent rate anyway.

It would be interesting to compare atmonauti with flat tracking. Really needs to be the same individual in the same suit for a valid comparison.

Okay, you have a point there about the max-time position in wingsuit.

Costyn van Dongen - http://www.flylikebrick.com/ - World Wide Wingsuit News

[Orange1 0]

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I've averaged 103 on my belly, on one of Roger Ponce's bigways. My best tracking speed was 79mph average (in a slick 4-way suit).

slightly off topic, how do you know what your average speed in the track is? (unless you do it for half the dive and get it off the protrack that way...??)

Skydiving: wasting fossil fuels just for fun.

[kallend 2,131]

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I've averaged 103 on my belly, on one of Roger Ponce's bigways. My best tracking speed was 79mph average (in a slick 4-way suit).

slightly off topic, how do you know what your average speed in the track is? (unless you do it for half the dive and get it off the protrack that way...??)

Track for the entire skydive. I often do that, just to practice.

Also one can download the data to a PC using "JumpTrack" software and select any portion of the skydive.

There are, of course, significant issues with instantaneous speeds froma ProTrack, but averages seem to come out OK.

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