Forums: BASE Jumping: BASE Technical:
Measuring freefall
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Colm

Sep 11, 2017, 9:29 PM
Post #1 of 8 (1039 views)
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Measuring freefall Can't Post

Does anyone have any experience measuring freefall distance and speed with, say, something like a theodolite, a transit, or a precision inclinometer, or any other technique? Please PM, thanks much.
Colm


(This post was edited by Colm on Sep 11, 2017, 9:32 PM)

c_dog

Sep 11, 2017, 11:18 PM
Post #2 of 8 (1002 views)
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Re: [Colm] Measuring freefall [In reply to] Can't Post

I used a flysight to get some numbers for static line jumps. Worked well.

hjumper33
Moderator
Sep 12, 2017, 3:14 AM
Post #3 of 8 (953 views)
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Re: [Colm] Measuring freefall [In reply to] Can't Post

Id contact Michael Cooper at flysight, id betcha he'd know a ton on the subject.

GreenMachine

Sep 12, 2017, 5:26 AM
Post #4 of 8 (914 views)
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Re: [Colm] Measuring freefall [In reply to] Can't Post

You could always come jump Wanda -- she has
8 platforms and we know how high each one is.

Colm

Sep 12, 2017, 3:54 PM
Post #5 of 8 (779 views)
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Re: [All] Measuring freefall [In reply to] Can't Post

Thanks for the great suggestions so far, including those who have contacted me privately.

I'm also going to try some tricks with video and inclinometry because I think I can get it even more accurate. With a fixed camera position, a designated exit point, a precision inclinometer, and a little trigonometry... I think it's possible to build an overlay distance scale, that can be superimposed on a side-angle video of a jump.

This would help record exact height and times of exit, deployment, bridle stretch, line stretch, inflation, and just about anything else you could see with a camera.

I'll email Michael C. I wish visiting Wanda was as easy as that, I'd love to take up your invitation GreenMachine!
Thanks Smile
Colm

c_dog

Sep 12, 2017, 5:02 PM
Post #6 of 8 (753 views)
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Re: [Colm] Measuring freefall [In reply to] Can't Post

Here's a sample of flysight data from 170'.


(This post was edited by c_dog on Sep 12, 2017, 5:03 PM)
Attachments: Screenshot (25).png (562 KB)

Colm

Sep 12, 2017, 6:10 PM
Post #7 of 8 (733 views)
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Re: [c_dog] Measuring freefall [In reply to] Can't Post

Thanks, which flysight viewing app is that? I only know the open source one on the flysight webpage. I might add some code to show the acceleration curve (i.e. 1st derivative of velocity) unless someone else has already done that and can share. It's Qt based and Michael's code is pretty easy to work with.

c_dog

Sep 12, 2017, 6:17 PM
Post #8 of 8 (728 views)
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Re: [Colm] Measuring freefall [In reply to] Can't Post

I uploaded the track to skyderby.ru.


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