One of the main tasks of rocketry is safe recovery, unless you’re building launchers into orbit. STR-03 uses a approach of separation, fast descend and at the end a slow descend..
At launchpad two parachutes will be inside the bottom section of the rocket. Above inside the top section a separation mechanism and the two stage recovery (release) mechanism is placed.
Once the apogee is reached the Flight Measurement System (FMS) activates the separation mechanism. It pushes the top section and the bottom section apart. Therefore pressurised gas is inserted into the body tube.
This separates the top section and the bottom section, thereby the drogue ($latex \O 660 \mathrm{mm}$) is deployed. This small parachute pulls also the deployment bag with the folded main chute outside the body tube.
With this setup – and the small chute deployed – STR-03 descends at an approximate velocity of $latex 14.7 \frac{\mathrm{m}}{\mathrm{s}}$. The advantage of this approach is minimized drift due to cross winds. This is a real hazard because of the proximity to the sea.
This velocity would be rather high for landing.
To minimize the final impact energy the main chute with a diameter of $latex 1800 \mathrm{mm}$ is deployed. Two loops are released with the two stage recovery mechanism (green part) and the chute is being deployed. The slow descand rate is $latex 5.2\frac{\mathrm{m}}{\mathrm{s}}$.
The last image shows the final setup. If all goes according to plan, STR-03 will land softly in the sand of Biscarosse.