Sep 17, 2012, 12:19 PM
Post #1 of 9
Exit separation spreadsheet
I read through the latest "45 degree rule" thread recently and remembered that I did the maths for exit separation a while ago for a piece of coursework.
I've attached an excel spreadsheet if anybody's interested. It shows how much separation you'll have on opening with different times between exits, and the different speeds of each group. All the green cells are editable. All units are in metres and seconds, but I've added a unit converter. Group 1/2 TV is the terminal velocity of each group. This is used to estimate their coefficient of drag. Total throw is your horizontal distance between exit and pull. K1 and K2 are the 2 groups coefficients of drag.
If anybody wants to check the maths or have a look at how it's done, I can upload the write up.
(This post was edited by gs8613 on Sep 17, 2012, 1:12 PM)
Sorry but I cannot open your file. Could you change it in simple XLS.
I am into mathematics therefore I am interested to see more details.
I made a program a couple of years ago on my graphing calculator HP 48 GX to calculate the spot based on wind direction and speed at 0, 3000, 6000, 9000 and 12000 ft. In this program I took in account the forward throw due to the ground speed of the airplane at altitude. In summary, this program makes a sum of 4 vectors (direction and length) and the result is like : 3500 ft at 340. We can really fast find out the spot on an aerial picture of the DZ on which I have drawn circles every 500, 1000, 1500, 2000, 2500 ft ...etc including geographic radials from 0 to 180 to 360 degrees by increments of 10 degrees. If intersted just tell me. My program let you know each operation and tell you what it actually does. I have also a sample calculation by hand to validate the program.
Thanks for your calultaions. In my calculation the jumper forward speed at exit due to airplane speed (provided it is flying horizontally against the wind at altitude over the calulated spot) is the : (ground speed of the airplane x 5 seconds)/2 which represents the horizontal distance made by the jumper at exit. See explanations.