Overview and status

Coming soon. RustStand is in development and not available yet. This page describes what it is designed to do; details may change before release.

What RustStand is

RustStand captures static tests of solid rocket motors. A Raspberry Pi at the test stand records thrust, chamber pressure and video, and RustStand apps on your phone and computer watch and control it over WiFi. It is part of the RocketSalvo family: it takes the formulation from RustPEP and the grain from RustCore, and sends measured burn-rate values, a and n, back to RustPEP.

RustStand is measurement only. It never controls igniters, relays or a countdown. “Arm” arms the recording.

Where it stands

The desktop app and the stand software already run end to end against RustStand’s built-in motor simulator: the live view, automatic start and stop, the test library and replay. Next comes support for real DAQ hardware, starting with the LabJack T7, then video, PDF reports, the phone apps and the link to RustPEP and RustCore.

How it fits together

Load cell, pressure transducer --> DAQ --+
USB camera ------------------------------+--> Raspberry Pi 5 (records to its SSD) --WiFi--> RustStand apps
                                                                                         phone and computer
RustPEP and RustCore <--> RustStand desktop app: formulation and grain in, measured a and n out

The Pi records everything locally, so a WiFi dropout costs the live view, never the test.

A test, start to finish

1. Open the app at the stand. It finds the stand, and the status bar turns green.
2. Pick the formulation, batch and grain, and confirm the motor details.
3. Run the pre-test check: sensors live, zero stable, calibration current, check weight passed, camera locked, disk space, battery and signal.
4. Tare with the motor loaded, then press and hold Arm.
5. Fire the motor with your club’s own ignition system. Recording starts and stops on its own.
6. Results open automatically with the metrics, curve and video. Add photos and notes; the test syncs to the desktop library later.

Automatic recording

Once armed, the stand keeps the last few seconds of every channel in memory. Recording starts when thrust rises clearly above the noise and stays there, and includes those seconds before ignition. It stops after thrust has stayed below 5% of the peak for a second, plus a short post-roll. The stand states are the same in every app: Idle, Armed, Recording, Processing, Done. All thresholds are adjustable, and the raw data is always kept, so the trim can be redone.

What each test gives

• Thrust: total impulse, motor class and designation, burn time per NFPA 1125 (from rising through 5% of peak to falling below it), action time, peak and average thrust, time to peak.
• Pressure: peak and average chamber pressure, time to peak.
• Performance: delivered specific impulse, c* and thrust coefficient, each against RustPEP’s theoretical value; the Kn curve from the RustCore grain.
• Burn rate: burn-rate points (pressure against burn rate) that feed the fit of r = a·Pⁿ.
• Quality flags: clipping, signal dropout, a pressure spike consistent with a CATO, chuffing, and a baseline shift after burnout.

Fitting a and n

The full fit uses three or more tests at different throat sizes. A single test with a pressure trace gives an early estimate by Nakka’s pressure–time method. Every fit shows its pressure range, R² and propellant temperature, and is sent back to RustPEP to show under the formulation.

Calibration

Every channel is calibrated through its whole chain: sensor, amplifier if there is one, and DAQ input. Load cells use a guided wizard with three to ten known masses, loaded up and back down; pressure transducers use a reference gauge. A check weight before each test confirms the calibration, and warnings appear when a calibration is old or a part of the chain changes. Each test keeps a copy of the calibration it used, and the raw voltages, so it can be reprocessed later with a corrected calibration.

Hardware it is designed for

• Stand computer: Raspberry Pi 5 with Raspberry Pi OS 64-bit and an NVMe SSD. A laptop with the DAQ plugged into it can also act as the stand.
• DAQ: LabJack T7 first. Planned later: LabJack T4 with the LJTick-InAmp, MCC 118 and 128 DAQ HATs, MCC USB devices, the PhidgetBridge, and the Waveshare ADS1256 HAT.
• Sensors: load cells (raw bridge or conditioned output); pressure transducers with 0.5–4.5 V, 0–5 V, 0–10 V, 4–20 mA or millivolt output; Type K thermocouples and PT100 RTDs.
• Camera: a USB (UVC) camera with JPEG output, for example 720p at 120 frames a second. To align video and data to the frame, an LED in your own ignition circuit can be placed in view and wired to a spare DAQ input; RustStand only senses it.
• Network: the stand makes its own WiFi network, or joins an existing one, or uses Ethernet. Apps pair with a one-time code, and one app controls the stand at a time.

Exports

.eng and .rse thrust curves, CSV, a PDF report, and, from the desktop app, a video with the thrust curve and readouts overlaid.

Price, licensing and the release date are not decided yet.