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Parachute Vocabulary
Quick overview of different aspects of a parachute and the correlating vocabulary terms:
| Term | Definition |
|---|
| Canopy | - cloth surface that inflates to a developed aerodynamic shape to provide the lift, drag, and stability needed to meet performance requirements
- can be modified with different geometries
|
| Confluence Point | - point of convergence of all suspension lines of a parachute
|
| Crown Area | - region of the canopy above the major diameter of the inflated shape
|
| Gore | - material of canopy between radials
|
Radials | - provide structural continuity across the canopy from the vent to the suspension lines
- load bearing member
|
| Skirt | - portion extending below the major diameter of the inflated canopy shape to the leading edge of the canopy
|
| Suspension Lines | - length = distance from the canopy skirt to the confluence point
|
| Vent | - small circular opening at the center of the crown or side of parachute
- simplifies fabrication and provides flow-through relief to initial surge of air at start of inflation
- vent porosity plays large role in determining inflation time and structural loads
|
Image from the Advisory Group for Aerospace Research & Development (AGARD).
https://apps.dtic.mil/dtic/tr/fulltext/u2/a246343.pdf
Geometry Characteristics
Images from the Advisory Group for Aerospace Research & Development (AGARD).
https://apps.dtic.mil/dtic/tr/fulltext/u2/a246343.pdf
Design Trends
High Drag Coefficient is produced by...
- Decreasing the porosity, which also produces a less stable parachute and a higher opening force.
- Conical, multi-conical, quarter-spherical canopy shapes.
- Long suspension lines because they increase the inflated diameter.
 | Images from the Advisory Group for Aerospace Research & Development (AGARD). https://apps.dtic.mil/dtic/tr/fulltext/u2/a246343.pdf S_o = canopy surface area including the vent area and all openings and slots in canopy, ft^2 C_D_o = parachute drag coefficient related to canopy surface area, dimensionless x_o and x_p are interchangeable in this directory. |
Geometries Compared
This section will cover different parachute designs that are relevant to our use case of the Phoenix drogue. Note: there are many other main types of parachutes that are not included here because their use cases were not appropriate for the Phoenix drogue goal.
| Parachute Type | Advantages | Disadvantages | Ranking for Phoenix |
|---|
| Cross | - low-cost replacement for the ringslot parachute
- stable, design decreases oscillation
| - meant too be used more for aircraft, stabilization and slowing down of mines
| 2 |
Disk-band-gap | | | 3 |
| Hemisflo Ribbon | - good for supersonic deployment up to Mach 3.0
- useful for drogue application at supersonic speeds
- hemisflo experiences less flutter and breathing of parachute
- good performance at higher dynamic pressures
| - Phoenix drogue will not be deployed supersonically, so this is not needed
| 4 |
| Conical Ribbon | - good drogue deployment at speeds of M < 1.5
- good structural integrity
- stable
- Apollo and Mercury drogues
| | 1 |
| Guide Surface | - good damping characteristics
- pressure distribution independent of oscillation angle
| - low drag - used for stabilizing payload that is supposed to fall quickly
| 6 |
| Ringslot | - useful for decelerating object with large wake behind it
| | 5 |
| Ballute | - optimal for use at high altitudes
- can withstand supersonic velocities
- generates a high amount of drag for its mass
| - not useful, not really seen in industry since Goodyear
- has not been tested that much
| 7 |
Common Problems and Solutions
Sources
