Overview
The way in which the various Recovery soft goods (e.g. lines, parachutes) are packed inside the cup and booster coupling section will play a direct role in the deployment dynamics. The various soft goods also influence flight vehicle dimensions by requiring a minimum volume. This page seeks to determine the minimum Recovery stowage volume and the most effective packing arrangement for mission success.
Main Parachute Packing Volume
For information on packing the main parachute into the deployment bag and packing the drogue parachute into the booster coupling section, click here.
When packed by hand into the SkyAngle DFB XL deployment bag, the main parachute occupies a cylinder of approximately 13" in length and 16" circumference, for a total volume of approximately 265 in3. Under tight compression the volume is 161 in3. Its shroud lines are 0.15" in diameter and are 126" in length. Taken together, all 16 shroud lines occupy approximately 36 in3.
Webbing Packing Volume
Webbing lengths subject to change, particularly due to updated forebody wake constraints. The webbing lengths (which are currently expected to increase) can be divided into three categories:
Main Parachute Length
The Main parachute webbing length is WA,B. As of 1/15/2018, the total length is 474". Two different possibilities for materials are tubular nylon (1" and 5/8" width, both approximately 0.1") and 2000lb braided Kevlar. The resulting weight and volume are shown in the table below:
Cross Sectional Area (in2) | Volume (in3) | Linear Mass Density (lb/ft) | Total Weight (lb) | |
|---|---|---|---|---|
| Tubular Nylon 1" | 0.1 | 47.4 | 0.0274 | 1.08 |
| Tubular Nylon 5/8" | 0.0625 | 29.6 | 0.0171 | 0.68 |
| 2000lb Braided Kevlar | 0.0154 | 7.3 | 0.00454 | 0.18 |
As described in the Webbing Materials Trade Study, we currently expect to use braided Kevlar, but have provided the tubular nylon in the table above as descope options.
Drogue Parachute Length
The Drogue parachute webbing length is the combination of WA,E,F,G (aka WE,F,G) and WC,D,F. As of 1/15/2018, the total length is 472". As described in the Webbing Materials Trade Study, we will be using 750lb braided Kevlar.
Cross Sectional Area (in2) | Volume (in3) | Linear Mass Density (lb/ft) | Total Weight (lb) | |
|---|---|---|---|---|
| 750lb Braided Kevlar | 0.00487 | 2.3 | 0.00157 | 0.062 |
Mission Package to Fin Can Length
The mission package to fin can length is WA,H. As of 1/15/2018, the total length is 295.4". As described in the Webbing Materials Trade Study, 2000lb braided Kevlar and 1/2" tubular nylon are both viable options.
Cross Sectional Area (in2) | Volume (in3) | Linear Mass Density (lb/ft) | Total Weight (lb) | |
|---|---|---|---|---|
| 2000lb Braided Kevlar | 0.0154 | 4.5 | 0.00454 | 0.11 |
| 1/2" Tubular Nylon | 0.05 | 14.8 | 0.01371 | 0.34 |
Hardware Packing Volume
Hermes hardware includes quicklinks, Tender Descenders, and swivels. The volume of each of these components are estimated as rectangular or cylindrical boxes, as well as the number of components (click here for current estimates on quicklink and swivel count). Components are roughly divided into those that will go inside the Mission Package during integration and those that will go inside the booster.
| Unit Weight (lb) | Unit Volume (in3) | Count | Total Mass (lb) | Total Volume (in3) | Mission Package Count | Mission Package Volume (in3) | Booster Count | Booster Volume (in3) | |
|---|---|---|---|---|---|---|---|---|---|
| Quicklinks (220lb) | 0.02 | 0.140 | 7 | 0.14 | 0.98 | 6 | 0.84 | 1 | 0.14 |
| Quicklinks (880lb) | 0.07 | 0.594 | 1 | 0.07 | 0.594 | 0 | 0 | 1 | 0.594 |
| Quicklinks (1000lb) | 0.12 | 0.891 | 3 | 0.36 | 2.673 | 3 | 2.673 | 0 | 0 |
| Swivels (300lb) | 0.01 | 0.143 | 1 | 0.01 | 0.14 | 0 | 0 | 1 | 0.143 |
| Swivels (1500lb) | 0.05 | 0.442 | 3 | 0.15 | 1.33 | 2 | 0.884 | 1 | 0.442 |
| Tender Descender Bodies | 0.07 | 1.21 | 2 | 0.14 | 2.43 | 2 | 2.43 | 0 | 0 |
| TOTALS | 0.87 | 8.15 | 6.827 | 1.32 |
Total Volume
Some notes about this estimate:
- Worst-case estimate w.r.t main parachute packing
- Neglects packing placement, which may worsen things
- Webbing lengths may change
- Webbing materials chosen to correspond to webbing materials trade study results
- 2000lb braided kevlar for main parachute webbing
- 1/2" tubular nylon for mission package to booster webbing
| Weight (lb) | Volume (in3) | Mission Package Volume (in3) | Booster Volume (in3) | |
|---|---|---|---|---|
| Main Parachute (with deployment bag) | 2.905 | 255 | 255 | 0 |
| Drogue Parachute (with deployment bag) | 0.52 | 54.6 | 0 | 54.6 |
| Webbing | 0.582 | 24.4 | 22.1 | 2.3 |
| Hardware | 0.87 | 8.15 | 6.827 | 1.32 |
| TOTALS | 4.877 | 342 | 284 | 58.22 |
Because v1.0 of the cup has 341 in3 of useable volume, a redesign will likely not need more space..
Preliminary Packing Arrangement
Some preliminary thoughts on packing arrangement are shown below:
A preliminary packing arrangement is also illustrated below:
