Medusa Drogues
Responsible Engineers: Claire J, Jenna B, Ezra E, Sophia C
Background
Drogue was chosen to be a disk-gap-band parachute which is intended to operate at low dynamic pressures at high altitudes and at supersonic speeds, with better stability than solid flat canopy. See this wiki page for additional research done on parachute selection.
Geometries
See diagram below for parameter matching. Geometries were found using DGB standard of disk, gap, band, and vent areas of 53%, 12%, 35%, and 0.37% of the nominal area (calculated using the selected nominal diameter).
Booster Drogue:
-8 gores
Parameter | Value (in) | Calculation Notes |
Nominal Diameter (Dp) | 54 | |
Nominal Area (S) | 2290.22 | pi*(Dp/2)^2 |
Geometric Porosity | 12% | |
Vent Diameter (Dv) | 3.28 | pi*(Dv/2)^2 = 0.0037*S |
Disk Diameter (Dc) | 38.88 | Dc/Dp = 0.72 *from Phoenix |
Gap Height (h2) | 2.25 | 0.12*S/Band Length |
Band Height (h3) | 6.56 | 0.35*S/Band Length |
Band Length (l=8*e) | 122.145 | pi*Dc |
Suspension Line Length (lr) | 90 | 2.3*Dc |
Sustainer Drogue:
-8 gores
Parameter | Value | Calculation Notes |
Nominal Diameter (Dp) | 36 | |
Nominal Area | 1017.88 | pi*(Dp/2)^2 |
Geometric Porosity | 12% | |
Vent Diameter (Dv) | 2.190 | pi*(Dv/2)^2 = 0.0037*S |
Disk Diameter (Dc) | 25.92 | Dc/Dp = 0.72 *from Phoenix |
Gap Height (h2) | 1.500 | 0.12*S/Band Length |
Band Height (h3) | 4.375 | 0.35*S/Band Length |
Band Length (8*e) | 81.430 | pi*Dc |
Suspension Line Length (lr) | 60 | 2.3*Dc |
Materials:
Fabric Ripstop by the Roll 1.1 oz Ripstop Nylon, Uncalendared;
Size 46 nylon thread
Kevlar Webbing (check type)
Technora lines (check type)
Manufacturing Steps:
Cut out octagon (disk) and rectangle (band) pieces with extra seam allowance on all sides out of nylon ripstop (seam allowance of 1 inch, to be double-folded)
Fold ½ inch hems (double-folded) of the disk and band pieces and sew using double stitch with nylon thread
Cut out the radial Kevlar reinforcements and mark where the loops for the lines should end and fold
Sew ends of the band together
Sew on radial Kevlar reinforcements from center through each vertex of the disk and the bad, leaving sufficient gap between the pieces and leaving the loops on either end for the lines
Thread vent line through loops in the radial Kevlar reinforcements and finger trap in place; sew to secure
Cut out 39in of thin Technora for lines → lines should be 30.6in
Tie one end of line in bowline knot to chute through the created loops of the radial Kevlar reinforcements
Mark 30.6in on all lines
Tie bowline loop on end of thin Technora lines and check for length of 30.6
Run around and make sure chute works
References:
https://apps.dtic.mil/dtic/tr/fulltext/u2/a246343.pdf
https://ntrs.nasa.gov/api/citations/19700023573/downloads/19700023573.pdf
