Freefalltime/distance

Jolly Jumper · November 19th, 2001, 02:24 AM

Interesting ! but the freefall is very individual after 4 sec.! When jumping bigwalls the chart is useless! you start(hopefully) to fly after 4 sec. then the aerodynamics get very complicated to calculate. The chart is something that (maybe) was useful back when bellyflying straight down was what we did, but a good track reduce your vertical fallrate significantly! The only way is to go visual and carry a pro dytter or video. In the part of bigwall-country i live (Norway) we now have 4 walls 30 sec.+ according to the chart we would all be dead!!!

From Karlskraatind Romsdal we had a girl doing 31 sec and she had 45 degree 900 m forward and 900 m downward so this kind of thing is getting out of date!:D

guest · November 19th, 2001, 04:07 AM

The girls weight was propably 45 kilos (90 pounds) and she had a goretex windproof jacket. No wonder it does not fit into the chart... The chart try to tell you how fast a STONE dropped stright down will fall. Since we all are different, and wear different clothes at the exit, we would need a personal chart for each of us.
You must also consider the wind and the termic. One day you can have an unbeliveable track, next day you bearly go forward, at the same spot with the same gear... :* :* :* :* :* :* :* :* :* :* :* : Have a nice day.:9

Jolly Jumper · November 19th, 2001, 05:05 AM

The smilies say more than a tousand words!!
karsk hard & BASE safe:-)

guest · November 19th, 2001, 06:55 AM

Hello Jolly Jumper,
basically I agree with you about the fact that each jumper has got his/her own terminal velocity in box and moreover terminal vertical velocity while tracking.
The tables give you, yet, a very good idea of the order of magnitude of vertical terminal velocity that you can expect out of a jump. I agree that if you track you change your vertical (and horizontal!!!) terminal velocity, and more depending on how good you are to track, but, in my humble opinion, while tracking you cannot dimish your vertical terminal velocity by more than 20÷25÷30% from your "box vertical terminal velocity".
So, tables just give you the standard vertical terminal velocity for a jumper weighing 100 kg and frefalling in box position and they are very good in giving an order of magnitude of your speed/distance fallen. Of course, if you want to be more precise, you need to determine in another way (skydiving computers, for example) your vertical terminal velocity while tracking, then with this number your can play a little bit with the parameters (suspended weight, body area and "shape coefficient" (box, headdown, tracking...)) and find which combination gives you your desired (=known from experimental data=skydiving computer) vertical terminal velocity. With these data, you can create your own freefal table.
If you like, I have got an Excel file in which there is, beyond the formulas written in full, a table in which, after having entered your own parameters (that give you YOUR terminal velocity), you can read quite an accurate customized freefall table. That is a quite a good approximation of reality (i.e., if do not track as usual, the table is no more valid!!!!!).
If you are interested, I can send you my Excel file so you can enjoy yourself in customizing it for you and for your friends.
Stay safe out there
Blue Skies
Andrea
#689

P.S.: I am trying while skydiving your "penguine" tecnique of tracking, but still have to check data of effectiveness of tracking with my GPS. Once done, I shall let you know!!!

Jolly Jumper · November 19th, 2001, 07:30 AM

Please send it to olejorgen.bryn@ark.ntnu.no

Good to have some positive discussion on the board! not all this bad vibes that seems to flourish here....:7

guest · November 19th, 2001, 11:32 AM

I have just sent you a copy of my file.
Still I am not sure about your e-mail address, I hope it works. Let me know!!!
Stay safe out there :D
Blue Skies
Andrea #689 :7

guest · November 19th, 2001, 12:08 PM

Can you please send it through to me too. Thanks!
nflynnj@hotmail.com

guest · November 19th, 2001, 12:37 PM

Done!!!
Stay safe out there :D
Blue Skies
Andrea #689 :7

guest · November 19th, 2001, 01:36 PM

could ya mail it to me too ----thanxxxxx
grimleaper@basejumper.net

guest · November 20th, 2001, 01:09 AM

Ha, the pengiun technique ! Great name ! And contrary to what people say, you can feel the difference on a skydive. I used to call it the Charlie Chaplin track. I don't have any hard data on whether it improves big wall jumping, but it appears so.

/Lukas

guest · November 20th, 2001, 01:27 AM

Done!
But I also sent a copy of my Excel file to Mick begging him to post a read-only copy of it somewhere on the BASE Board for use by any fellow jumper.
Stay safe out there :D
Blue Skies
Andrea :7
#689