Page History

...

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.

Drag coefficients, canopy area ratio, diameter ratio as a function of suspension line ratio...

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.

Other Considerations

Material considerations:

as porosity increases, drag coefficient decreases
low porosity yields a faster inflation time and generates a higher opening shock

Design considerations:

orifice coefficient
vent hoop: single vs double
larger parachutes = lower porosity

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	23
Disk-band-gap			verified inflation and drag performance for M = 0.05 - 2.7 good inflation at low dynamic pressure good stability lower mass than conical ribbon general application = supersonic drogue	good for main parachute, not really drogue	23
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	might be hard to manufacture	1
Guide Surface	good damping characteristics pressure distribution independent of oscillation angle high stability	low drag - used for stabilizing payload that is supposed to fall quickly	6
Ringslot	useful for decelerating object with large wake behind it	more useful for aircraft	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

Problem	Solution
Skirt inversion	reefing

Sources

Parachute skirt damage	reinforcement, reefing, choice of material
No inflation	reduce canopy porosity near vent
Flutter of canopy	due to supersonic deployment, keep supersonic consideration in mind during design