Separation and Recovery Subsystem
Calculated 823 lbf opening and 1,230 lbf snatch loads to size Argo’s recovery lines and hardware. The earlier black-powder configuration was 18.7 lbm within a 20 lbm allocation, with a $1,076 bill of materials. I led its second integrated test; the CO₂ redesign is in preparation for full-system testing.
Current status: two black-powder integrated tests complete; CO₂ full-system test in preparation
System Architecture & Lines Diagram
System Architecture
The subsystem passed through four design reviews. Its design structural-margin target is 2.0 FOS; component proof testing and integrated deployment tests are separate verification steps.
For the 135 lb dry-mass rocket targeting 100,000 ft, the planned sequence is nosecone separation and drogue deployment near apogee, followed by main-parachute release at 2,000 ft above ground. The main stays packed during drogue descent. Paired flight computers and release devices provide separate actuation paths; the component arrangement is shown below.
Nosecone Shape & Recovery Integration
The nosecone is a recovery-system component, so any shape change must preserve parachute packaging, attachment interfaces, and separation behavior. I am also comparing candidate nose shapes in RASAero II as part of the aerodynamic investigation that grew out of the aerocover trade. No replacement profile has been selected. See the nosecone aerodynamic trade, recorded simulation results, and comparison limits.
Parachute & Recovery-Line Selection
I compared 23 commercial main and drogue parachute candidates across drag coefficient, descent rate, packing volume, mass, rated load, and cost. The selected architecture uses a 42 in heavy-duty Spherachute drogue and an existing 144 in high-performance main. The analytical model predicts approximately 118 ft/s during drogue-only descent and 21.4 ft/s at landing under the main.
I carried the calculated opening and snatch loads into recovery-line sizing. The line-strength study required approximately 2,905–4,938 lbf depending on termination efficiency, supporting selection of 6,000 lbf Kevlar line and subsequent Brummel-splice verification.
Architecture Trade Study & Load Analysis
I compared system architectures, COTS flight computers, and vacuum-tolerant separation mechanisms. The earlier black-powder configuration met the 20 lbm allocation at 18.7 lbm, with a $1,076 bill of materials.
- Release hardware: Four Catclaw cable cutters, two tender descenders arranged in series along the release line, and two flight computers. Paired Catclaws act on the same zip tie; either cutter can sever that restraint. Either in-series tender descender can open the release line. Each deployment charge, Catclaw, and tender descender has two e-matches, one connected to each flight computer, providing two firing paths per device.
- Hardware Development: Redesigned, manufactured, and tested the Catclaw cutters, supported by engineering drawings and load analysis.
- Load analysis: Compared five published methods to calculate an 823 lbf parachute opening load and a 1,230 lbf snatch load, then carried the governing loads into recovery-line selection and component checks.
Architecture Development & Packaging
The assembly and top-down CAD views above show the current nosecone packaging with hoist rings and CO₂ deployment cartridges. The diagrams below record the earlier black-powder packing plan and main-parachute arrangement; they explain the design progression rather than the current charge layout.
Catclaw Cable Cutters
The Catclaw is a separate black-powder-actuated release device: it holds a zip tie and drives a piston through it to break the tie. It is not part of the CO₂ nosecone-deployment mechanism.
I trimmed down the earlier Catclaw design and reshaped its slot to retain the piston after firing. I produced the manufacturing drawing and machined the aluminum body on a manual mill and lathe. The redesign reduced mass 49.5%, with a calculated 2.01 FOS.
All eight trials at the selected 0.7 g black-powder charge broke the tie. The 0.65 g setting usually worked but was not repeatable enough to select.
Testing & Iteration
Vacuum Testing & Deployment Iteration
I designed the installed door, adapter, and face seal for the 352 L vacuum chamber and operated component trials with my co-lead. The first CO₂ charge test began at a reported 0.011 atm; chamber design and pressure-measurement context are documented on the vacuum page.
One of three deployment charges failed in each of two sea-level black-powder integrated tests; the second also damaged the parachute bag and canopy. These results drove the separate CO₂ nosecone-deployment redesign. The Catclaws remain distinct black-powder-actuated releases.
Vinyl-container charges had appeared repeatable in standalone trials after the team standardized their manufacturing process. I recall roughly 7–10 trials at that stage, but the count was not logged and does not support a numerical reliability claim. The packed recovery assembly exposed failures that the standalone trials had not captured. I led the second integrated test and collaborated on the failure assessment that informed the CO₂ pivot.
Integrated-test observations and working hypotheses
Post-test evidence included a failed charge's ruptured sidewall and powder residue throughout the assembly. End-seal manufacturing variability was an observed concern and is the leading working explanation for inconsistent charge performance. Damage caused by a neighboring charge firing is a secondary hypothesis inferred afterward, not directly observed in sequence. Neither the relative contribution of those mechanisms nor the proposed incomplete-combustion sequence has been established.
The limited standalone-test population also left uncertainty in the earlier reliability impression; sample size is not itself a physical failure mechanism.
Test Operations Leadership
I authored the integrated vinyl-charge black-powder test SOP and led the second integrated test, including crew briefings and fire/abort decisions. My co-lead led the first test while I was in Australia. Post-test inspection and failure assessment were collaborative with teammates and our team director. I am preparing the CO₂ integrated-test SOP. My co-lead designed and programmed the pressure acquisition and analyzed its data.
See why we redesigned nosecone deployment around CO₂, and how the piercer was sized and tested
View the vacuum chamber: design, instrumentation, and testing
Recovery-Line Verification
I introduced Brummel eye splices in 1/2 in Fruity Chutes Kevlar shock cord to replace knots and reduce quick-links. The design rationale was near-full line-strength retention versus roughly half for some knots: approximately 2× termination strength. This is a literature-based rationale, not a measured strength gain for our Kevlar assembly.
I dynamically proof-tested the Kevlar cord termination to 1,800 lbf, approximately 1.46 times the calculated 1,230 lbf snatch load, without observed slip. The load reached the setup’s capacity; it does not establish ultimate strength or a measured strength gain over knots. Further setup details are withheld at the project director’s request.
Slow-motion dynamic test of the spliced recovery line
Planned Subscale Flight Test
Subscale testing has not started. The planned test will evaluate the recovery approach intended for Argo: keeping the main parachute packed during drogue-only descent before releasing it for landing. Argo’s planned drogue deployment at 100,000 ft and main deployment at 2,000 ft above ground are full-scale targets, not demonstrated subscale results.
Recovery Analysis & Verification Basis
These calculations summarize the recorded design margins. Component and line tests remain distinct from pending CO₂ full-system and flight verification.
Mass budget and line-strength selection
| Earlier BP configuration mass / allocation | 18.7 lbm / 20 lbm |
|---|---|
| Calculated shock / snatch loads | 823 lbf / 1,230 lbf from five published methods |
| Line-rating requirement | Approximately 2,905–4,938 lbf, depending on termination efficiency |
| Selected nominal line rating | 6,000 lbf |
| Dynamic proof load / calculated snatch load | 1,800 lbf / 1,230 lbf ≈ 1.46, rounded to approximately 1.5×; a proof-load ratio rather than an ultimate-strength FOS |
The selected 1/2 in Kevlar stock is rated up to 6,000 lbf before our termination is added. Published comparisons motivated an approximately 2× strength rationale relative to knots retaining about half the line strength; this is not a measured gain for our assembly. Marlow’s comparisons depend on rope and knot type. The Milne and McLaren study tested polyester, not our Kevlar Brummel termination, and treats apparent efficiencies above 100% as anomalous. The dynamic proof test reached 1,800 lbf at the setup’s capacity, approximately 1.46× the calculated 1,230 lbf snatch load, with no slip observed in that test. This does not establish ultimate strength or verify the 2.0 FOS design target.
Catclaw redesign and test scope
| Mass reduction | 49.5% versus the previous design |
|---|---|
| Calculated body margin | 2.01 FOS in the recorded analysis |
| Selected-setting test result | 8 successful tie breaks in 8 trials |
| Design change | Reduced body material and reshaped the slot to retain the piston |
The observed 8/8 result applies to the tested Catclaw configuration and selected setting. It does not establish universal 100% reliability or validate the separate CO₂ deployment mechanism.