Stratos IV is being designed to break records and reach space. To see how successful the mission was after its launch, the flight data needs to be saved and recovered. With this flight data, future Stratos missions can be developed to reach higher goals each time by learning from past experiences – therefore, the recovery of the nosecone is of utmost importance.
In order to properly recover the nosecone, a whole recovery subsystem has to be integrated into the Stratos IV rocket. This subsystem is known as the recovery bay. In here, two important parachutes are located, a hemisflo drogue parachute and the main parachute of Stratos IV which is a Disk-Gap-Band parachute. The drogue parachute is responsible for slowing down and stabilizing the nosecone after the rocket separation, that is why this parachute is the first one to be deployed. Once the nosecone’s supersonic speed has slowed down to a subsonic regime, the main parachute can be deployed. For the Disk-Gap-Band deployment, a pilot chute is used, this pilot chute is exerted from the canister where the main is located. With the drag force generated by the pilot chute the parachute bag that holds the main parachute is pulled out and, as the force exerted on the pilot chute increases, the bag is pulled away releasing the main parachute. The main parachute is responsible to bring the nose cone to sea level at the desired touchdown speed of 20 m/s.
On the 11th of March 2019, the main parachute was tested in the wind tunnel of the TU Delft. This test was successful, as the parachute performed better than expected regarding stability and drag, which is the reason a Disk-Gap-Band was chosen. It provides sufficient drag while remaining stable due to its geometry, which lets some air pass through decreasing the turbulence of the flow. Besides the actual behavior of the parachute, the deployment of the Disk-Gap-Band with the bag and pilot chute was tested, which also showed the expected behavior. This means that the wind tunnel test was a successful one. In the coming months, a reserve main parachute will be made as well as
the drogue parachute, both will be tested in the wind tunnel for validation.