Parachute Research Group
The Parachute Research Group (PRG) works on expanding and improving the already available recovery systems, and coming up with new designs. PRG is currently working on different projects, such as Stratos III and project Aether. Furthermore, PRG also works independently on recovery systems within DARE.
In 2018, multiple test series in the wind tunnel of the TU Delft are planned. These tests will be used to gather valuable data on the performance of parachutes. Additionally, the previously designed subsystems are being improved, these are the mortar system and the explosive bolt. The improvements focus on minimizing the weight while maintaining the current performance.
|Lars Pepermans||Team Leader & Chief Recovery Stratos III|
|Bram Koops||Chief Recovery Aether|
|Mark Rozemeijer||Secretary-Stratos III & Aether|
|Felix Kuhnert||Member-Stratos III|
|Esmee Menting||Member-Stratos III & Aether|
|Noah Suard||Member-Stratos III & Aether|
|Matteo Serman||Member-Stratos III|
|Carlos Bislip||Member-Stratos III|
|Olivier Kuijpers||Member-Stratos III|
|Ramanathan Gurumoorthy||Member-Stratos III|
|Thomas Britting||Member-Stratos III|
The nosecone of Stratos III will be recovered, because there payloads and important flight data will be stored. The recovery of Stratos III will happen after the rocket has reached apogee. After the apogee, the tank will separate from the nosecone. This separation will make the recovery of the rocket easier due to the fact that there will be a mass reduction, and because the nosecone will go into a flat spin that will cause an increase in drag.
Because the nosecone will be spinning, a large parachute cannot be deployed, due to the fact that it would entangle with the nosecone and therefore, it would not inflate. In order to stop the spin, a small parachute will be deployed, a drogue parachute, this drogue parachute will be made from Twaron, a light and strong para-aramid material. Furthermore, to ensure that the lines of the drogue do not entangle, a cold gas deployment device (CGDD) will be used. This system will shoot the drogue at a velocity of 30 m/s.
At about 1000 meters, the main parachute will be deployed. This parachute will be pushed out by a spring system, which is sufficient because the nosecone will not be spinning anymore. Once the main parachute inflates, it will decelerate the nosecone to below 20 m/s for a safe water landing.
After Stratos II+ the next large-scale project within DARE is project Aether. This project is a collaboration between multiple teams of which the PRG team is one of them. PRG is responsible for the complete recovery system of the rocket.
The recovery section was designed as a two-stage parachute system: a hemisflo ribbon drogue chute and a cross main parachute. The drogue parachute is deployed sideways from the rocket from a mortar: a high-pressure CO2 vessel that deploys the drogue chute a high-speed. At a predetermined altitude an explosive bolt will be activated so that the main parachute gets deployed.
In March 2017 the project got delayed due to technical problems. This allowed the team more time to develope and improve the sub-systems of the rocket. Just after the summer of 2017 the team rapidly expanded with multiple new members, most from DARE’s first year project. This allowed the team to start the development of new innovative systems.
PIP (Parachute Investigation Project)
PIP is a new PRG project. PIP deals with the investigation of parachute inflation at high dynamic pressure. The project is has just started, therefore, more information about it will follow shortly.
Hardware and Testing
Gas powered ejection and pyrobolts
The team has developed a gas powered ejection system called ‘mortar system’, which will deploy the drogue chute at high-speed sideways through the rocket. This prevents the rocket from having to separate into multiple segments for the parachute to deploy. By using this system the ability to predict the stability of the rocket and the flight dynamics involved are greatly simplified. After the drogue has deployed it will be attached at the bottom of the rocket with an explosive bolt. This bolt is custom designed and uses a small amount of black powder to break a steel bolt in half. Once this mechanism is activated in flight, the drogue should be separated from the main rocket structure and only remain attached to the main parachute. The main parachute will then be pulled out by the force of the drogue and deploy, ensuring the rocket will have a low end-velocity on touchdown.
The designs for both parachutes are another innovation within DARE. The drogue parachute design is a complex hemisflo ribbon parachute consisting out of numerous pieces of fabric stitched together. This intricate design should ensure the parachute can survive the high speeds in the initial phase of the descend while also maintaining its stability. The main parachute will be a standard cross-shaped parachute or a small variation thereof. The current design calls for a 15m2 parachute which will be the largest parachute ever developed by DARE.
All new subsystems (the mortar, explosive bolt and parachute designs) have been tested already and were mostly successful. Static test campaigns were held at the end of the summer and in September to prove the concepts behind the mortar and explosive bolt. Ultimately, all systems were combined in a CanSat rocket and launched in September 2016. During this launch, all systems that we wanted to test worked. Unfortunately, the wires holding the parachutes broke off on deployment, which meant that the CanSat came down without a parachute
To further improve our knowledge and confidence in the parachute system, a series of wind tunnel experiments were performed in October 2016. During this test campaign, 4 different main parachutes were tested and 1 drogue parachute. These tests were used to expand the knowledge on stability, shock loads and other parameters of the parachutes. Results of these tests will be published later.
The PRG team came from the capsule team, which started out as a sub-team of the Stratos II project. In this project, the team was responsible for the structural integrity of all the components above the engine as well as for the recovery system. The main components that were designed and produced were the glass fiber nosecone shell, the payload section and a dual-spring-deployed parachute system.
The whole capsule section was designed with numerous iterations and tests along the way. Eventually, the final design for Stratos II and Stratos II+ was developed. This was composed out of a double clamp band system held together by spring steel. At predetermined moments this steel band would release, deploying the drogue and the main parachute, respectively. On top of this dual parachute system was the payload section, with a U-shape rack housing the external scientific payloads. To finalize the capsule, the inboard electronics were housed in the top of the nosecone, combined with an antenna for data telemetry and video down-link