Help! I need freefall speed information please!

[imstu 0]

Hello, my name is Stuart. I am already a licensed skydiver (C, SL-I, IAD-I). I am trying to help my step-son (13 y.o.) with a science fair project. He loves watching skydivers and wants to do a skydiving related project. We are comparing freefall vertical speed as it is influenced by body position. I am going to do 2 jumps belly to earth, 2 sitting, and 2 head down. These will be recorded on my Pro-Track and printed out. What we need to find right now is at least 3 articles pertaining to freefall speed in the different positions. I have been searching all over the net, but not finding anything. Please help this aspiring future skydiver! Thank you for any help you can give us! Stuart and Robert.

[peek 20]

http://www.pcprg.com/baro.htm

[darkwing 4]

Sounds like a good project. Just remember, don't confuse theory with reality. It is OK to compare them, but don't expect them to be entirely consistent.

-- Jeff
My Skydiving History

[imstu 0]

Hi Gary,
Thank you very much for the helpful article! That is exactly what we need. I found it interesting that you had to go thru so much for the 'dampening' to get accurate readings. I had no idea it was such a complicated issue. You certainly had alot of creative solutions and put tremendous time into finding solutions. We are hoping to find two more articles long these lines that we can use as references to complete the research portion of the project. Thanks again for your help!
Stuart & Robert

[imstu 0]

Hi Darkwing,
It's a fun project for me because I "have to jump" several times to complete it. It's a dirty job, but someone has to do it! What we are looking to show with this project is the different positions cause a speed differential. We are not trying to say the differential from belly to sit will always be 41.4 mph etc. We are just trying to show that there is and increase in speed from belly to sit, and from sit to head down. The pro-track graphs are just to 'spice it up' a bit with some real data to show we actually did the experiment (jumps). Thank you for pointing out that there will be inconsistencies in our readings. It would have been extremely frustrating to try to come up with an exact number (speed differential) between the positions. Too many variables. (especially with the way I sit fly! LOL). Thanks again!
Stuart & Robert

[hackish 8]

From a scientific point of view I think you need to think about the number of square inches you are presenting to the airflow comparing these in head down and sitflying and belly to earth should put you in the ballpark. Maybe you could get someone below to photograph you in each position, scale them and get your son to measure the square area.

-Michael

[Fozz 0]

Quote

From a scientific point of view I think you need to think about the number of square inches you are presenting to the airflow comparing these in head down and sitflying and belly to earth should put you in the ballpark. Maybe you could get someone below to photograph you in each position, scale them and get your son to measure the square area.

-Michael

Michael is correct! I did a project like this with a kids science club of 8 th graders years ago we used a flood light underneath the students on a board (arched , sit, stand) between 2 desks and had the kids trace each others shadow on butcher paper then calculated basic surface area of each position and correlated it with difference in speed for each position they went to 2 different DZs and collected data and asked for specific dive and data and even measured some of the divers who were very cooperative and the kids came up with some great curves on surface area vs speed

John Fosgate
"In the end, its always best to choose the hard right over the easy wrong." LouDiamond
MB 4310
www.N3Racing.com

[grannyinthesky 0]

I've been looking for projects for a math/physics concepts class that I'm working on with another instructor. This idea could lead to something and getting the jumping data would be fun besides. Thanks for the idea. Pat

"safety first... and What the hell.....
safety second, Too!!! " ~~jmy

POPS #10490

[imstu 0]

Hi Michael,
Thank you for the great idea! This would add alot of detail to the project. It offers a more detailed explaination of why there would be a change in vertical velocity. The pictures would make it more visually understandable too. Sounds Like I may have to do more jumps to get the pics right. Damn the bad luck...LOL. 8-) Thanks again for the idea!
Stuart & Robert

[asmund 0]

http://hypertextbook.com/facts/JianHuang.shtml

from
http://www.google.com/search?source=ig&hl=en&rlz=&q=freefall+speed&btnG=Google+Search

I like subway.