Sisyphus — Subsystem

Flight Stages

The flight software runs through three stages: countdown, stabilizing ascent, and descent/recovery.

Software tells the flight computer how to react to sensor inputs and command hardware outputs.
Code coordinates countdown, powered ascent, descent detection, and recovery actions.
Real-time logic links IMU/barometer estimates to TVC control and pyro events.

Countdown

A multi-press gate reduces accidental launch events.
An audible buzzer countdown and LED cues signal launch timing.
Gyro offsets and barometric zero are finalized before ignition.
At countdown completion, the ignition channel is fired.

Sisyphus setup next to the pad during countdown — Pad-side setup and final checks during the countdown stage.

Sisyphus idle on the pad during countdown — Idle on the pad before ignition.

Stabilizing Ascent

Dual-axis TVC runs a PD stabilization loop using angle and angular-rate feedback.
Control outputs are constrained and mapped to servo geometry for stable actuation.
Sensor fusion and altitude-rate tracking inform stage transitions and safety checks.
If tilt exceeds safe bounds, emergency recovery logic can be triggered.

Sisyphus flames cool launch during stabilized flight — Flames cool launch at the start of stabilizing ascent.

Sisyphus stabilizing rocket during ascent — Stabilizing rocket with active TVC during ascent.

Descent and Recovery

Once descent is detected, the controller transitions to recovery behavior.
Recovery development is currently split between validated parachute recovery and in-progress propulsive recovery.
Final status cues are provided through onboard buzzer and LEDs.

Parachute Recovery

Parachute deployment is currently the flight-proven recovery path.
Descent detection and staged recovery events are integrated in the live flight code.
This mode provides a reliable fallback while propulsive recovery matures.

Sisyphus parachute descent during recovery — Parachute descent during the recovery stage.

Sisyphus rocket destroyed on the ground after recovery — Post-flight condition: rocket on the ground after impact.

Propulsive Recovery (In Progress)

This recovery mode is actively under development and is not yet flight-proven.
Current work focuses on transitioning from parachute-only recovery to powered terminal recovery.
Low-altitude state transitions, throttle-window timing, and attitude constraints are still being iterated.
Target outcome: controlled touchdown using active TVC authority through the final descent phase.

Landing leg deployment development test video (in progress). Hover to play.

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