Main Parachute
We conducted a quick survey to determine the best way to pack the main parachute. We experimented with four different packing methods. We began the first three by following Section 9.5.1 in Poynter, "General Canopy Pleating Instructions." In general, we found the canopy pleating process to be much easier than the Raziel legacy, full canopy folding method. One specific advantage is that it required less space for integration (we lined up 3 narrow tables in the Unified Lounge, but the integration table in lab could just as easily be used, assuming has been cleaned and has fresh paper). Another advantage is that, unlike the legacy procedure, the shroud lines remain almost entirely stationary during packing, which reduces the number of tangles introduced in the process.
When trying out all of the methods, we used sand bags from lab as parachute "shot bags" to flatten the canopy. We always kept the lines out of the deployment bag, as we do not plan to pack the lines within the bag for Project Hermes.
Method 1: Pleating + Vertical Z Fold
A general picture of the final configuration is shown below.
After following the pleating instructions, z fold the canopy, making sure that the apex/vent hole ends on the closed end of the deployment bag (where it is closest to the connection point). It was very easy to pack the parachute inside the deployment bag. We secured the ends of the shroud lines (which were not packed in the bag but rather laid out flat). and pulled on the top of the bag with a fish scale to determine the max load necessary to pull the main parachute out. We found that it took approximately 7.2 lbs at maximum to pull the main parachute out.
Overall, this was the easiest and most orderly of all configurations to pack. On the other hand, it had the maximum amount of force required to pull it out. Here is a picture of what it looked like after we pulled the deployment bag off slowly:
Method 2: Pleating + Bunched/Transverse Z-Fold
This method is almost identical to method 1 except for the orientation of the z folds in the deployment bag. As we were pushing most of the canopy (except at end in the skirt region) inside the deployment bag, we actually did not use z-folds but rather just took handfuls of the chute, bunched it up, and pushed it in. To see an example of the bunching technique, check out this video from Fruity Chutes. The following picture is of what it would look like if the chute had been perfectly z folded inside of the deployment bag. The bunching would look like a less orderly version of this:
From the outside, its packed configuration looked like this. As you can see, the volume was very small when packed in this configuration. This is because we can very effectively compress the parachute inside the deployment bag like a spring. For scale is a 1000lb quicklink.
Again, we did the same experiment with the fish scale and found that it took somewhere between 2 and 3 lbs at maximum to pull out the main parachute. Here is what the canopy looked like after the deployment bag was pulled off:
One big benefit of this configuration is that the parachute acts like a spring and wants to push itself out of the deployment bag, which is probably why it took so little force to pull it out. In comparison, the parachute pushes circumferentially on the deployment bag in method 1. This will increase the hoop stress on the deployment bag and expand it, thereby making it more difficult to pull out of the cup, and then making the parachute more difficult to pull out of the bag.
Overall, we'd like to use this method for Project Hermes. We should investigate more to determine if we can better z fold the parachute into the bag as we pack it, as opposed to before, and also see if it is better to z fold or to bunch.
Method 3: Pleating + Rolled
Again we followed the pleating method from Poynter. We then rolled the canopy up, starting at the apex/vent. When it was finally packed, it was a little lumpy inside the deployment bag. It took about 2.5 lb at maximum to pull the deployment bag off of the canopy. A big downside to this configuration is that the canopy comes out as a spiral/twisted, which will result in unequal load distribution during canopy opening.
Method 4: Raziel Legacy
For our last method, we followed the steps for packing the main parachute on Project Raziel. You can download a pdf of the summarized procedure here: Raziel Packing Procedure (Summarized).pdf. This method is basically a rolling method but instead of pleating the canopy to begin with, you fold it in half multiple times. It took approximately 3.74 lbs at maximum to pull the deployment bag off of the canopy.
Drogue Parachute
TBD
Resources
Dan Poynter, The Parachute Manual: A Technical Treatise on Aerodynamic Decelerators, 3rd ed.