unisat

Rocket Avionics Bay — Operations Guide

Profile key: rocket_avionics · Mass cap: 500 g · Volume: 250 cm³ Template: mission_templates/rocket_competition.json ·

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1. Mission class

Competition-class suborbital rocketry avionics (IREC / SA Cup / Team America). 50 × 50 × 100 mm bay that sits inside the rocket’s electronics coupler, drives dual-deploy parachute pyrotechnics, and logs flight data at high rate.

2. Physical envelope

Parameter	Value
Mass cap	500 g
Dimensions	50 × 50 × 100 mm (rail envelope)
Volume	250 cm³
Power generation	0 W (battery-only)
Nominal consumption	2.0 W
Battery	2× 14500 Li-ion, ~3 Wh

3. Regulatory context

• IREC (Spaceport America Cup) rulebook — thrust-weight ≥ 5, dual-deploy parachute mandatory above 10 000 ft AGL.
• NAR / Tripoli HPR certification for the operator.
• FAA Part 101 (USA) for amateur rockets ≤ 150 000 ft AGL.
• Radio: ISM 915 MHz or 433 MHz, ≤ 250 mW ERP.

4. Subsystem matrix

Subsystem	Status
OBC	✅
High-g IMU (± 16 g)	✅
Barometer (MS5611)	✅
GNSS	✅
UHF / ISM telemetry	✅
Dual-deploy controller	✅
Camera	⚠ (optional, mass-limited)
ADCS	❌
S-band	❌

5. Build

make target-rocket-avionics

Compile-time macro: MISSION_PROFILE_ROCKET_AVIONICS=1. Sets PROFILE_FEATURE_DESCENT_CTRL=1, PROFILE_FEATURE_ORBIT_PREDICTOR=0.

6. Mission config

cp mission_templates/rocket_competition.json mission_config.json

Key fields:

• mission.competition.target_altitude_m — 10 000 ft / 3048 m is the IREC basic category; 30 000 ft / 9144 m for advanced.
• mission.competition.dual_deploy — true mandatory for IREC.
• subsystems.comm_uhf.frequency_mhz — 915 MHz (US) or 433 MHz (EU).
• satellite.dimensions_mm — match your rocket’s coupler bay.

7. Mass & volume validation

Metric	Value	Status
Total mass	0.34 kg	≤ 0.50 kg ✅
Volume used	145 cm³	58 % of 250 cm³ ✅

Adding a small camera is feasible if the payload specialist can keep it under 80 g.

8. Typical mission phases

Rocket-specific phases (from mission_types.ROCKET_COMPETITION):

ground_checkout → armed → boost → coast → apogee
                                              ↓
                                      drogue_descent
                                              ↓ altitude < main_deploy
                                      main_descent
                                              ↓
                                            landed

Phase	Sensor focus
ground_checkout	IMU, barometer, telemetry
armed	Launch-detect predicate: accel > 3g
boost	High-g IMU (up to 15g peak)
coast	Barometer primary, IMU secondary
apogee	Eject drogue on pressure reversal
drogue_descent	Measure descent rate ~15–25 m/s
main_descent	Main eject at ~300 m AGL, rate ~5 m/s
landed	GNSS downlink for recovery

9. Testing checklist (bench)

Legend: [x] = verified in software / CI / SITL (passes in the current release); [ ] = requires bench hardware, RF range test, or flight-day field activity — team must sign off manually.

• High-g IMU confirms ± 16 g range on a shake-table drop test.
• Barometer reads ascent + descent consistent with an altitude profile from a previous flight or simulation.
• Ejection charges fire at commanded altitude in a drop test (actual pyro inside a blast chamber).
• Redundant altimeter (if fitted) agrees with primary within 5 % during pressure sweep.
• GNSS reacquires fix within 30 s post-boost.
• Launch-detect predicate triggers within 10 ms of 3 g threshold crossing.
• Data logger writes at 200 Hz for 10 min without loss.

10. Flight-day (launch-day) checklist

• Pre-launch weight + CG measurement matches predicted.
• Battery > 95 % charged.
• Pyro continuity on both channels confirmed.
• Armed-in-holdoff-mode until rocket is on the rail.
• Telemetry link heard by ground station from the rail.
• Weather within rulebook wind / visibility limits.
• KeyRotationPolicy reports ok on ground console.

11. Known limitations

• No active attitude control — aerodynamic stability only. Fin design + centre-of-pressure must be correct on the rocket.
• GNSS shadowing during boost — expect fix outage for the first 10–15 s of ascent. Do not use GNSS in launch_detect logic.
• Single OBC: pyro firing failure ends the flight. Many teams fly a second redundant altimeter (Featherweight, EasyMini) in parallel — UniSat plays well with them but does not depend on them.

12. Post-flight debrief

Capture:

• On-board flight data (200 Hz IMU / 50 Hz barometer / 10 Hz GNSS).
• Ground-station PCAP of the telemetry link.
• Photographs of the rocket on recovery.
• Parachute unfurl / damage assessment.

Analyse against rulebook:

• Apogee within 10 % of target (IREC scoring).
• Dual-deploy timing correct.
• Recovery GNSS coordinate within search perimeter.

File a flight report under docs/operations/flight_reports/<event>_<date>.md.

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