Structures & Recovery
The Structures and Recovery team is an active project of DARE and it is one of the multiple teams that belong to project Aether. Project Aether consists of the production and launch of a rocket to test new experimental technologies for future DARE missions. Besides from project Aether, the Structures and Recovery team is working on other projects. These projects aim to contribute with the knowledge and expertise needed for innovative technologies for future DARE rockets.
The team is split into two departments, which are:
- Structures department
- Recovery department
The Structures and Recovery team 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 fibre 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+ were 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 finalise the capsule, the onboard electronics were housed in the top of the nosecone, combined with an antenna for data telemetry and video downlink.
The structures department is currently working on creating a database of structural composite knowledge. This database will be used for future rockets and concepts to efficiently design a new system. In order to accomplish this, numerous studies and tests will be carried out by the Structures department. Additionally, the department is investigating a multi-stage separation system. This system should ensure a proper separation, in case a two-stage rocket is designed. Moreover, the department is also working on the structure of the Aether launcher.
Current projects of the structures department
Structure of Project Aether
The structure of the capsule will be similar to Stratos II+, meaning it will be a glass fibre shell. The nosecone will again house the flight electronics and antenna. All the different sections of the rocket will be connected using identical couplers. This was designed so that all sections can be made independently of each other, and that section could eventually be added or removed if necessary.
Furthermore, for project Aether the department is conducting tests to verify the structural integrity of the composite components. Based on the data from these tests, the team will decide whether or not to improve or replace certain components. These tests also provide useful inside in the performance of the production process.
The structure department also researches into multiple technologies. The main purpose for these technologies to be implemented in future DARE rockets. The research projects are split into three, composites, staging and testing.
At the moment there is research being done on composites. For this, composites at high and low temperatures are being studied. The reason for this is to eventually use composites for engine cases and (cryo-)tanks. The main purpose of this is to reduce the overall weight of the rocket.
Another topic of research is staging mechanisms. These mechanisms will serve to provide adequate separation and impulse, as well as structural integrity of the rocket during flight. Furthermore, this research helps to achieve one of the DARE goals, which is on multistaging.
Because most ways of testing materials can be detrimental, different ways of non-destructive testing are being looked into, such as visual testing and thermography. Non-destructive testing has never been used in DARE.
|Maneesh Verma||Systems Engineering & Manufacturing|
|Sayyam Khurana||Manufacturing & Test Engineer|
|Guido Monechi||Staging Mechanism & Simulations|
|Kevin Krüger||Structures & System Engineer|
|Nicolas Fosséprez||Systems Eng. & Testing|
|Yovanka Rucita||Test & Structures|
|Martin Osowaski||Manufacturing & Staging mechanism|
|Benjamin Keltjens||Staging Mechanism & Simulations|
|Tristan Faschinger||Manufacturing & Structures|
The recovery department is working on expanding and improving the already available systems. Multiple test series in the wind tunnel of the TU Delft are planned for 2018, these tests will be used to gather valuable data on the performance of parachutes. Additionally, the subsystems that have been previously designed are being improved, these systems are the mortar system and the explosive bolt. These improvements are focused on saving weight while maintaining the current performance.
Most of the hardware for project Aether has already been completed, but with the additional time for research, several systems might be updated before the launch of the rocket. The results from tests, that will be conducted in the coming period, will determine whether or not this is feasible.
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.
|Esmee Menting||Head main parachute development|
|Lars Pepermans||Head mortar development|
|Zyanya Rabilotta||Public relations|
|Mark Rozemeijer||Head explosive bolt development|
|Noah Suard||Head drogue parachute development|
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.
Project Aether and the team
After Stratos II+ the next large-scale project within DARE is project Aether. This project is a collaboration between multiple teams of which the Structures and Recovery team is one of them. This team is responsible for the structural elements of the rocket, such as nosecone, engine tube and shells for the recovery and ACT section, as well as the complete recovery system of the rocket.
The structural elements for the modular section of the recovery and ACT systems were designed and produced out of lightweight aluminium. The sections were designed to be modular so they could be removed, swapped or replaced if necessary for this or future rockets. The engine tube, to house the engine and secure the fins, was produced from carbon fibre. Since the nosecone has to be radio transparent, glass fibre was the chosen material for this. 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.