Webbing lengths must be selected carefully to satisfy several constraints such that parachutes enter the airstream (and do not remain confined within the vehicle). For Project Hermes, the webbing constraints and resulting calculations are summarized below:
For the Hermes Pathfinder vehicle, the relevant dimensions are:
| Variable | Length (in inches) | Description |
|---|---|---|
| hmp | 51.3 | Total height of mission package |
| lmp | 17.8 | Distance from diaphragm to end of mission package |
| lfc | 4.75 | Depth of booster coupling section |
| hfc | 40.5 | Total height of booster including coupling section |
| RB | 27 | Height of deployment bag |
| DM | 114 (9.5 ft) | Diameter of the main parachute |
| RM | 80.6 | Height of the main parachute (found using 0.707 aspect ratio): RM = DM*0.707 |
| SM | 126 | Length of shroud lines on the main parachute |
| DD | 34.4 (2.87 ft) | Diameter of the drogue parachute |
| RD | 24.3 | Height of the drogue parachute (found using 0.707 aspect ratio): RD = DD*0.707 |
| SD | 48 | Length of shroud lines on the drogue parachute |
Using these variables, a set of constraints was generated to ensure successful Recovery system deployment. The constraints are summarized in the table below:
| Constraint | Description |
|---|---|