Vacuum Test Chamber
Delivered the installed door, tube adapter, and face seal for a working 352 L recovery-test chamber operated at a reported 0.011 atm. Sized the 6061-T6 door for a 1,663 lbf full-atmospheric load with a calculated 2.12 FOS against yield.
Purpose & Contribution
The chamber let the recovery team compare deployment components under reduced pressure before system-level sea-level tests.
Chamber Design & Test Operations
I designed the 352 L chamber assembly, including its door, tube adapter, and face seal. My co-lead fabricated the door and adapter, designed the clamps and pressure instrumentation, and wrote the acquisition software used to record and analyze the data.
- Test environment: Evaluated sealed separation charges and avionics for a rocket targeting 100,000 ft. The reported 0.011 atm chamber condition is 1.1% of standard atmospheric pressure.
- Seal sizing: Sized the 381 square-cross-section face seal using the Parker O-Ring Handbook; the corrected groove and installed seal are described below.
- Pump Architecture: Used a Robinair 15310 3 CFM pump for faster initial roughing and an Alcatel 2008A medium-vacuum pump for slower evacuation to a deeper vacuum. This staged procedure now reaches the test condition in approximately 30 minutes. The behavior described here is what I observed in our setup: the Alcatel reached a lower final absolute pressure.
- Test operations: Initiated test ideas, operated the chamber with my co-lead, and iterated the plumbing and evacuation procedure. Integrated-test leadership is documented on the recovery page.
- Material Reuse: Reused pumps and other equipment found in the lab, along with available stock for the adapter and door assembly.
Installed Door, Adapter & Seal
I sized the installed 6061-T6 door for a 1,663 lbf full-atmospheric load: 14.7 psi across a 12 in unsupported diameter. The plate is 0.25 in thick. The simply supported Roark model predicts 0.0848 in deflection; the separately recorded calculator stress of 16.5 ksi gives 2.12 FOS against yield. Inputs and assumptions are retained below.
I also sized the tube adapter and size 381 face seal. An initial O-ring groove exceeded the gland-fill target; the groove was corrected before the hardware was fabricated and installed. The assembled chamber operates as intended.
CAD of the installed 6061-T6 door and tube adapter
Door Calculation Basis
Hand calculations for sizing the door; these values are predictions for the modeled plate and pressure condition, not measured results.
Pressure load and selected plate
| Design pressure differential | 14.7 psi (full-atmospheric case) |
|---|---|
| Unsupported diameter | 12 in |
| Loaded circular area | 113.1 in² (π × 6² in²) |
| Total door load | 1,663 lbf (pressure × area) |
| Selected door | 0.25 in 6061-T6 aluminum plate |
Roark plate results
| Recorded peak bending stress | 16.5 ksi (approximately 114 MPa) |
|---|---|
| Predicted maximum deflection | 0.0848 in |
| Material yield strength used | 240 MPa (approximately 34.8 ksi), selected from the BlueScope 6061-T6 data sheet; not a measured stock property |
| Calculated minimum factor of safety | 2.12 against yield, using the corrected material strength; displayed stress values are rounded |
| Verification status | Uniform pressure on a circular plate supported around its outer circumference. The confirmed Roark model is simply supported around the outer circumference. The workbook calculates deflection with that model; its stress value is separately entered from a calculator. No measured door deflection or door FEA is available. |
Material source: BlueScope Distribution, Aluminium 6061 data sheet. The sheet covers extruded products; 240 MPa is the selected design input, not certification of the installed plate. The predicted 0.0848 in deflection is about one-third of plate thickness; the selected plate-model assumptions need to be checked for that deflection.
Installed seal and groove revision
| Installed seal | Size 381 face seal at the door and tube adapter |
|---|---|
| Groove revision | Initial gland fill exceeded the target; the groove was corrected before fabrication |
Deployment Test Progression & Measurement Limits
I operated dozens of characterization and component trials spanning legacy black-powder charges and CO₂ piercers. These chamber trials evaluated pressure response and reduced-pressure operation; the integrated deployment tests were conducted separately at sea level.
I also operated flight-computer checks and CO₂ component tests while iterating plumbing and gauge configurations.
Integrated deployment results and test leadership are documented on the recovery page; the CO₂ page covers the piercer sizing and pending system test.
The physical gauge and pressure transducer rarely agreed within 0.5 inHg. The stated 0.011 atm starting condition and the trace near 0.18 psi are approximate indications with an unresolved measurement discrepancy; the instrument reference and any offset correction must be established before interpreting the pressure as a precise altitude equivalent.