Parachute Trade Study: Andrew Welsh
Conical
Ribbon
Reliability:
High
Mass:
Less
Mach Number
0.1<M>2.0
Average Oscillation Angle ±3°
Drag Coefficient Range
.5 to .6
Opening Force Coefficient 1.05 to 1.3
Disc-Gap-Band
High
More
M<0.5
±10 to 15°
.52 to .58
1.3
Conical
Ribbon
Reliability:
+
Mass:
+
Mach Number
+
Average Oscilation Angle
+
Drag Coefficient Range
+
Opening Force Coefficient +
Disc-Gap-Band
+
+
-
+ Positive
- Negative
Notes:
As a practice NASA will only use conical ribbon and disc-gap-band parachutes because
they are well tested, used on previous missions, and highly reliable. Therefore we will
only provide a comparison between conical ribbon and disc-gap-band
Conclusion:
For our purposes a conical ribbon parachute will be the best choice. Both parachutes
have a high reliability, but conical ribbon parachutes have a lower oscilation angle which
will be preferable during deployment. Drag coefficients are comparable and the conical
ribbon parachute MAY have less mass leading to lower costs. The conical ribbon
parachute will have lower opening force coefficient which will be beneficial to the
airship, helicopter, and instruments. Conical ribbon parachutes are also better suited for
mach numbers between .1 and 2.
References:
1) pg. 5-5 Parachute Recovery Systems Design Manual by T.W. Knacke