BLAST stands for Biliquid Launch and Space Technology and is our team’s current main project. In its course, we are aiming to develop a sounding rocket which combines several innovative and complex technologies.
Recovery
The BLAST recovery system will be a single chute system. In order to mimic the two-stage behaviour of the traditional drogue-main-combination, we are currently developing a self-made active skirt reefed main parachute. By choosing this approach, we hope to drastically decrease total system mass and volume.
We are planning on using a reefing line to control the opening of the parachute. While this will allow us to move the actuators away from the parachute skirt into the rocket’s hull, it also creates two parallel lines, which have to swivel around the same axis. To avoid any entanglement of the two lines, we are designing a custom hollow swivel which will allow the reefing line to pass through the main line swivel.
Since there is relatively little research in active parachute reefing systems at small scales, we will perform tests to determine the parachute type best suited for our configuration. In early wind tunnel testing, we have already found the traditional round canopy parachute to be very unstable in comparison to other parachute shapes.
There are no concrete plans for ejection and reefing actuation yet. For testing purposes and the upcoming HyDra 3VO launch, where we will fly a two parachute recovery system, we have already developed a mortar ejection system and self-made line cutters for the ejection of the main chute. To decrease the mass of the Blast ejection system, we are looking into other means of deployment.
Avionics
The term “avionics” encompasses all electrical systems active during the mission. Our central task is to ensure that the parachutes are deployed at the right time, since this is vital to mission success. In order to ensure its reliability, a redundant system based on a modern microcontroller is developed in-house from the ground up.
Our other tasks include data collection and transmission, as well as the physical structure and power supply which will be needed in order to perform aforementioned central task.
Fluid System
Our fluid system is marked by cutting-edge features, notably the use of a 3D-printed main valve, ensuring weight reduction and a more compact design. Rigorous testing procedures are implemented to guarantee system reliability, validating its performance under diverse flight conditions.
Key achievements include the development of robust depressurization mechanisms, such as self-designed pressure relief and vent valves, ensuring secure and controlled tank evacuation. Collaboration with Ground Support Equipment (GSE) specialists ensures a smooth tanking process, optimizing the integration of the fluid system with ground support infrastructure.
The team’s focus on a highly integrated system prioritizes optimization of weight and volume, resulting in a compact and efficient rocket design. Constant pressure regulation is maintained through mechanical pressure reduction, thus adapting to changing conditions during flight.
Structure
We are currently developing a linerless CFRP oxidiser tank using an in-house developed epoxy resin matrix which does not react with nitrous oxide. On top of the cheaper manufacturing cost, this Type V pressure vessel will have significant weight reduction compared to an aluminium-liner tank, which was used in our previous rocket and is currently the state-of-the-art in oxidiser tank development. Tank bulkheads will also be manufactured from CFRP instead of aluminium, thus further increasing our mass savings.
All components will be optimally designed to the flight profile of our rocket and will be verified through mechanical, thermal, and aerodynamic simulations as well as rigorous testing, including load cycle and vibration tests.
To push the light-weight engineering of our rocket to its limits, we will also be using RADAX connectors to join the various parts of our rocket together as this compact connection allows us to reduce the total length of the rocket.
Further innovations that we wish to realise in the course of this project include retractable rail buttons that will improve the aerodynamics of the rocket’s flight, an integral tank design as well as manufacturing our engine mount from light-weight composite materials.
Propulsion
During Project BLAST, the propulsion subsystem will focus on developing the liquid engine „C2H5OH Academic Demonstrator“, short CHAD. Its final version will be named Kilo CHAD, since its thrust will be within the kilonewton range. The CHAD engines use liquid ethanol as fuel and liquid nitrous oxide as oxidizer. While the first iterations of our liquid rocket engine will be cooled ablatively, additive manufacturing of Kilo Chad will enable us to create the geometry needed for regerative cooling. TRUMPF already produced one such engine for us.
In its current form, CHAD will have a chamber pressure of 60 bar. This is achieved by pressurizing the propellants with high-pressure helium. We chose this gas as it is light and inert, and thus will not interfere with the combustion process.
In order to develop a viable engine, we first tested several injector types with water, then with the respective fuels. Soon, we will conduct hot-fire tests in order to verify ignition and chamber geometry, for which will utilize the subscale demonstrator CHAD. With the lessons learned from these tests, we will conduct similar tests with ablatively cooled versions of Kilo CHAD. If all goes to plan, we will go on to develop regeneratively cooled engines with three injectors each.
Our first design of CHAD features a combustion chamber made from phenolic paper and a graphite nozzle, encased in aluminium. The phenolic paper represents the material which will cool the engine by ablating during the combustion process. During the first hot-fire tests, we will measure the pressure within the combustion chamber as well as the pressure before the injector. We will also measure the engine’s thrust and temperatures across different surfaces in order to characterize our liquid rocket motor.
The regenerative cooling capability of the full-scale engine Kilo CHAD will be achieved by having ethanol (blue) circulate through cooling channels within the combustion chamber and nozzle walls. These cooling channels are included during the 3D printing process. As is common, we chose to use the fuel for cooling, since the oxidizer may react with the engine’s material. Of Course, there will be a loss in pressure throughout the cooling channels, which is in part compensated by the warming of the fluid. We will also adjust the pressure of our ethanol tank in accordance with data gathered during cold flow and hot fire tests.
Said warming of the fluid also changes its density. If the ethanol is heated at high pressure past a certain temperature, two-phase flow may occur. This refers to a state in which liquid and gaseous flow take place simultaneously. In designing the injectors, we have to take this into account, as well as the varying pressure that may result from the phase changes.
Render of Kilo Chad with visible cooling channels (blue), with the inside of the combustion chamber represented in red.
Ground Support
At HyEnD, we are not just building rockets, we are also launching them. This brings up the Ground Support Equipment (GSE) for the upcoming BLAST project. Often the unsung hero, the GSE is critical in ensuring that each rocket launch is executed flawlessly. Without this essential subsystem, our rockets would remain on the ground. It plays an important role in fueling, pressurizing, and guaranteeing the safety of each launch. The GSE is an interdisciplinary subsystem, incorporating thermodynamics, mechanics, electronics, and more.
Our goal for the new GSE is straightforward yet ambitious: we aim for high reliability and adaptability. Building on the success of N2ORTH’s GSE, which operated flawlessly on each launch, we are setting the bar even higher. The GSE is set to tackle all challenges, particularly in managing diverse components such as the propellants nitrous oxide and ethanol, as well as pressurizing gases such as helium and nitrogen.
In order to optimize our measurement, command, and control unit, we are integrating a commercial off-the-shelf data acquisition system. This system promises to enhance our data accuracy and processing capabilities significantly. For BLAST, we are building a new, extended launch rail, made to accommodate our launch parameters. We are also streamlining the fueling processes and hardware, aiming for maximum efficiency and safety. These integrations allow us to be more reliable, flexible, and future-ready.
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