UKHAS Wiki

UK High Altitude Society

User Tools

Site Tools


guides:parachute_sizing_chart

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
Next revision
Previous revision
guides:parachute_sizing_chart [2008/07/19 23:33]
127.0.0.1 external edit
guides:parachute_sizing_chart [2015/09/08 15:51] (current)
edmoore
Line 1: Line 1:
 +====== Quick video guide to parachute calculations ======
 +
 +To understand how to calculate your descent rate under a parachute, watch [[https://​youtu.be/​S7KujrsUB1w?​t=3h49m57s|this talk]] from the 2015 UKHAS conference.
 +
 ====== Parachute Sizing Cart ====== ====== Parachute Sizing Cart ======
  
Line 7: Line 11:
 For streamers the value on the left represents the streamer length - the data assumes that the streamers will have a 10:1 length to width ratio (i.e. the width will be a 1/10th of this value). ​ For streamers the value on the left represents the streamer length - the data assumes that the streamers will have a 10:1 length to width ratio (i.e. the width will be a 1/10th of this value). ​
  
-For parachutes the value represents the parachute diameter. Of the group of four lines the two inner solid lines represent what is considered the normal range of decent ​speeds for an average parachute (a parachute with a Cd value of about 1). The upper of these represents a decent ​speed of 3.5m/sec (approx. 11.5ft/​sec),​ the lower a decent ​speed of 4.5m/sec (approx. 15ft/sec). These two rates are normally considered to be the upper and lower bound of desirable ​decent ​speed - your experience may vary. +For parachutes the value represents the parachute diameter. Of the group of four lines the two inner solid lines represent what is considered the normal range of descent ​speeds for an average parachute (a parachute with a Cd value of about 1). The upper of these represents a descent ​speed of 3.5m/sec (approx. 11.5ft/​sec),​ the lower a descent ​speed of 4.5m/sec (approx. 15ft/sec). These two rates are normally considered to be the upper and lower bound of desirable ​descent ​speed - your experience may vary. 
  
-The upper dashed line in this group represents the slower ​decent ​rate for parachutes with a low coefficient of drag (a Cd of 0.75). An example of this type of chutes are those made from a single sheet of material (so called para-sheets) and are thus less efficient. The lower dashed line represents the faster decent rate for parachutes with a high coefficient of drag (a Cd of 1.5). An example of this type of chute are those made from many specially shaped segments of material sewn together. The PML "​DuraChute"​ sizes fall approximately in this area of the chart. ​+The upper dashed line in this group represents the slower ​descent ​rate for parachutes with a low coefficient of drag (a Cd of 0.75). An example of this type of chutes are those made from a single sheet of material (so called para-sheets) and are thus less efficient. The lower dashed line represents the faster decent rate for parachutes with a high coefficient of drag (a Cd of 1.5). An example of this type of chute are those made from many specially shaped segments of material sewn together. The PML "​DuraChute"​ sizes fall approximately in this area of the chart. ​
  
 {{guides:​parach1.gif|}} {{guides:​parach1.gif|}}
  
guides/parachute_sizing_chart.1216510403.txt.gz ยท Last modified: 2013/11/03 11:25 (external edit)