Launch Pad "Pantera"
Thanks to Robotunits, Pantera has a height of 6m, a width of 3m, and a length of 2m and with a variable starting angle, our rockets do have the best conditions for a good flight. The guiderails ensure a good connection between our prototype rocket DODO and Pantera. We look forward to the start of DODO and future rockets.
Update Aerodynamics 01.06.2021
Today we will show you some details of our air-brake system. To test it we are using 3D printing as a rapid prototyping method and we are adding the servo motor for movement. Through this, we are able to find out if we need to make adjustments to our design. When everything works the way we want to, we can then manufacture the parts from aluminum for our prototype rocket.
Update Propulsion 18.05.2021
As you can see, we are making great progress in assembling our fluid system.
To ensure maximum safety on our test stand, the fluid system possesses several safety valves, pressure and temperature sensors, and automatically controlled valves.
How do you ignite a rocket engine?
With another Rocket Engine!
Considering we also build our own solid booster, we can use it for the ignition of
our hybrid engine. It consists primarily of a mixture of potassium nitrate and
sorbitol. The source of the ignition is a modified electric match from our partner
We are currently conducting many tests to confirm the functionality and improve the chemical formulation.
Update Avionivs 04.05.2021
On today's technical Tuesday, we'll have a look at a simulation of the rocket's flight path and the controller.
To make sure that every single element on the rocket does its job like it is supposed to do, there are different states to check this throughout the flight. These states can be examined in the first graph.
After the ignition, the flight state changes to one. Once the thrust curve in the third graph reaches zero (booster burn-out), the flight state switches from one to two. Then, the controller deploys the airbrakes. As soon as the rocket reaches apogee, state three begins: the rocket descends using the parachute.
In the second state, a program calculates the projected apogee height, which is used as the signal to be controlled. It takes the output of the controller into account, which is why there is a discontinuity in the projected height graph. This is the moment when the airbrakes become effective.
As you can see, the predicted apogee height stays the same until apogee, which is an indication that the height calculator works well.
Today's update comes with a proper gust of wind 💨
We had a great testing day at the facilities of Rail Tech Arsenal (RTA) in Vienna. 🇦🇹 With their 5m wide and 6m high wind tunnel, we measured the deceleration force of our parachutes and tested the ejection system and the fins. 💨🚇 We started by testing our multi-phase ejection system, which was a great success. The first parachute was ejected due to overpressurized air, while the big parachute was held back in the nosecone with a custom-developed mechanism. By sending a signal to the module, the mounting opened up and the big parachute came out. 🪂 In the next experiment, we put the rocket on a rotating rod and by steered it to the side, the fins guided the rocket back to a stable position. We don't want small winds to alter our projection. Furthermore, by measuring the drag-force of the parachute, we can calculate the drag-constant, which is a characteristic property of the parachute. 🚀
Update Structure 06.04.2021
In the last few months, you saw many posts about the different modules and you have probably started to wonder how the assembly of all these parts would look like. Now the time has come! Today we proudly present you our complete prototype rocket “DODO”. 🚀 The rocket is divided into many different functionalities – our so-called modules. Each module fulfills its task. To make the rocket work, all components must stay together. That’s when the Structure module comes into play. All parts are held together by the connecting pieces and are shield from external influences by the load-bearing cover.
When constructing the individual assemblies, design errors that cause collisions are very quickly detected and can therefore be corrected effortlessly. ✔️ Design programs such as Siemens NX, which we use to make the assembly drawings, provide simple tools to calculate the center of gravity. The center of gravity is used for dimensioning the fins. 👈🏻
Solution for our last post 🕵🏻
Yesterday, the picture showed a task of a rocket nozzle which converts the high pressure in the combustion chamber into velocity. Optimally, the combustion chamber pressure at the exit (pe) should be exactly equal to the ambient pressure (pa). ➡️⬅️ If this outlet pressure is lower, it is referred to as an overexpanded nozzle; if it is higher, it is referred to as an underexpanded nozzle.🚀 As you can see on the second picture: That is why the rocket nozzles for vacuum are so much larger.☝🏻
Update Propulsion 23.03.2021
Here you can see a simulation of a rocket nozzle 🚀 Even though these images are nice to look at, they contain a design flaw that we placed on purpose. Can you spot it? 🕵🏻
Special Update of Propulsion
In order to test our hybrid rocket propulsion system in a repeatable and safe manner, we have developed an automated test stand. Due to its modular design, it can be easily modified or expanded for future projects. In addition to the verification of our calculation results, various research projects will also be carried out on our test stand in the future. Thus, our members can deal with certain topics in more detail in the context of their master's or bachelor's thesis and check their theories in practice right away. For more information visit the propulsion module page.
Update Aerodynamis 16.02.2021
Today we want to show you a simulation of our aerodynamics team. Our task is to examine the airflow along the aerodynamical parts of the rocket like the nosecone, the fins, and the air brake using CFD (Computational Fluid Dynamics). The results are to be validated in the future using a wind tunnel. 💨 This video shows the results of a CFD simulation located at the fins. Using Siemens Star-CCM+, we simulated how the air flows around the fins. The streamlines show how the air is moving along the airfoil, the colors show how the flow velocity behaves (blue = slow, red = fast). 🔵🔴 Using these results, we can determine how the rocket will behave after the engine cut-off with aerodynamical measures like the conical cover at the engine nozzle. This helps us to understand where vortices are formed and how they affect the drag of the rocket. 🌪➡️🚀
Our main activities
Have you ever wondered what the ASTG does?🕵🏻
In the picture, you can see our main tasks, ranging from 3D printing to holding weekly meetings. In order to achieve our objective of building a rocket, we have to work together and unite our passion and motivation to fulfill our goal. But we cannot do this on our own, every single one of us has an important role, which we need to carry out. Everybody is being updated on each other's work and accomplishments. This makes us a fantastic team where everybody contributes and plays a vital role in achieving our dreams.
If you want to stay tuned and learn more about what we do, visit us on Instagram @aerospaceteamgrazofficial !
Update Propulsion 16.02.2021
In the production of our fuels, the youngest manufacturing processes, such as 3D printing, meets one of the oldest: casting.
This photo shows one of the challenges in casting Paraffin-Wax. The cooling and resulting shrinkage of the material creates the voids seen in the photo. These are also called blowholes (Lunker). There are many ways to avoid these blowholes. Among other things, slower cooling, the use of additives, secondary pressing or centrifugal casting can be used. We are currently carrying out a wide range of tests to find the optimum solution for our fuels.
Facts for Friday
Interested in rocket-engineering and space technology?
Follow us on Instagram to get a freshly prepared, space-related fact each friday!
By the way, would you know the answer to the question in the image?
Find the solution on Instagram @aerospaceteamgrazofficial
Update Recovery 02.02.2021
In this short video we would like to introduce the Ejection System for our rocket DODO, which was developed by us, the Recovery Module. Our main tasks are the separation of the rocket and the release of the two parachutes. 🪂 At first, you can see the assembly of the whole Ejection System for DODO. This mechanism opens the cartridge to release the gas in the upper part of the rocket. 🚀
At a certain overpressure, the tip of the rocket is separated from the rest and a small parachute will be released. During the descend of the rocket, this parachute is limiting the speed of the rocket falling. Near the ground, a slightly bigger parachute is released, which slows the rocket down and allows a save landing. ⬇️✅
Moreover, you can see our first ground tests with the original small parachute. We used a software to track the nose cone for a velocity estimation. The nose cone flew with a max. speed of 57,92 km/h and up to 6,5 m. ☝🏻
Update System Admin 26.01.2021
As you might know building a rocket is not only about designing and developing. For achieving our goal to participate at the spaceport america cup in 2022, we need a good system administration to handle all the background activities. Therefore, thanks for the help from @hosttech_gmbh. Now we were able to streamline our internal management and planning processes with the usage of web-based tools such as FireFly 3, LeanTime or BitWardenRS.
In the image you can see one of the tools we use, that enable us to efficiently deploy new service as demanded by the rest of the team with minimal to no downtime for the rest of the services. 🚀
Update Structure 19.01.2021
These are the hull connectors for our first prototype rocket. Their main purpose is to align and affix the hull sections to each other and to transmit the forces of the parachute opening as well as wind loads.
The main point of focus was weight and to ensure good integration of the avionics and recovery module. We therefore settled on a frictionally locking coupling with 6 high-tensile bolts providing the needed clamping force. Keeping our weight goal in mind we added cut-outs which left us with the bare minimum material while still ensuring structural integrity. For easy access the recovery subsystem is mounted on 3 bars in front of the connector with the flight computer mounted directly inside the female coupling facing backwards. All parts will be machined from a high-strength aluminium alloy.
Update Aerodynamics 15.12.2020
This is our new and improved airbrake-design specifically created for the dodo rocket. It now features only 3 instead of 4 sliding brakes in order to match the number of fins on the rocket, and also to fit the design into a rather small diameter of 70 mm. On top of the 3 brakes are cavities for weight reduction and increased drag when braking. The whole assembly is actuated by a high-powered servo motor for maximum actuation speed and repeatability.
For manufacturing, most parts will be machined and made from aluminum for rigidity, high strength and low weight
Update Propulsion 08.12.2020
Hi, my name is Felix and today I share the topic of my bachelor thesis.
My bachelor thesis is about designing a Laval nozzle for our hybrid rocket engine. The requirements for the nozzle are high temperature resistant, light weight and a highly efficient expansion of the exhaust gas. To reach this target I am writing a program in python which takes over the data of the combustion and environment to compute the most efficient design. To withstand the high temperatures of the exhaust gas we are using graphite which is fairly lightweight and temperature resistant.
Update Avionics 24.09.2020
Our Avionics Dodo Concept:
These renderings show our current concept model for the prototype rocket Dodo. We attach our flight computer, telemetry and connector PCBs on a 3D-printed mount. The mount also contains enough space for the LiPo batteries that will power our components. In order to be able to communicate with the other systems of the rocket, we use 4 circular connectors at both ends. Finally, to increase the standby time of our system we implemented a magnetic charging connector for the system, allowing us to recharge our batteries while mounted in the rocket.