The Ares mission begins two years ago to fulfil the idea of creating a supersonic rocket within the university. Eventually, the mission evolved in the design of a multi-stage supersonic rocket with solid fuel.
The Ares II is intended to be a supersonic rocket build using the knowledge acquired in the design and launch of Ares I. Also, since the launch of Ares I the mission has gone through an upgrade thanks to the start of a collaboration with HP, which has let us improve the rocket design features to have a better performance thanks to the state of the art 3D printing techniques that this company uses.
In the present days, the rocket has already been designed and is being printed. An overview of the designed is presented.
For the fuselage design we used Adobe Fusion 360 and we had the following final result:
The orange interior cylinder is made of cardboard, it simulates the rocket engine. The purple piece is the interchangeable part which its interior diameter can be adjusted to the engine size.
The simulation results are the following:
- Security factor: The simulation showed a minimum security factor around 4, which ensures that our system will not break even in the maximum stress point.
- Maximum displacement: The simulation showed that the maximum displacement would be around 0,15mm which will not compromise the system or the mission.
- Stress study: The simulation showed a maximum stress around 5MPa, as our material alone (without fibreglass) is enough to withstand those stresses we should not be worried about breaking the system.
The objective of this bay is to contain the gunpowder components needed to deploy the parachute, which will be opened thanks to electronics a signal that will be sent at the precise moment that some conditions are validated and, afterwards, the burning system composed by an ignitor, gunpowder and a cotton thread will act opening the parachute.
This bay is mainly constituted by four parts: Two covers and two cylinders. These parts are assembled all together constituting a single unit. They are joined by screws and bolts.
The nosecone was designed using OpenFoam. The following data was obtained simulating compressible supersonic flow. The initial conditions considered in the simulations were:
- Nosecone length: 30 cm
- Rocket speed: 420 m/s (Mach=1.2)
- Exterior temperature: 27ºC
- Exterior pressure: 99000 Pa
The following figures show the simulation result using paraView, where the shown field is the air around the Ares nosecone. The profile of said nosecone can be seen in the left part of the figure.
The other image is a graphic where the velocity, pressure and temperature are shown around the nosecone surface as well as the rocket body. The nosecone is between the y=80cm and y=50cm.
Schematic design of the PCB
In order to provide a much clearer vision to the schematic of the PCB, all the components have been distributed in different groups according to the function they develop in the board. The additional parts that have been added have been highlighted in red in Figure 1, and the four main parts are the following: The first one is the support Atmega328p components, which are the essential parts to make the processor work. The second part is the Atmega 328P itself which includes all the connections to the other parts of the board. The third part contains the components and sensors, which in this case they are the flash memory, accelerometers, barometers, GPS and communications. The last part includes the ignition circuits that are the same as in the previous board version.
The parts that have been removed as a conclusion from the first launch are the XBee, as it did not work correctly; the LISS331 accelerometer chip that was really difficult to solder due to its small size; and the barometer, instead of soldering the microchip, the manufactured version was added.
Below, all the added components have been defined.
This is a Voltage Regulator that brings the 9V battery voltage to 5 Volts. This is required in order to make the ADXL193 accelerometer work as the input voltage needs to be from 5V. The connection scheme and the component images can be seen in the previous image.
The ADXL193 is a high-power unidirectional accelerometer, as it can sense accelerations inside the ±250gs range (1g equals 9,81 m/s2) in the direction of movement. It has been decided to buy the manufactured board in order to ensure the correct functioning. The decision to include this component was due to the fact that the simulations said that the rocket’s maximum acceleration was between 50 and 60 gs (490,5 m/s2 and 588,6 m/s2) and this is the only sensor that can withstand that force .
The MPU6050 is another accelerometer that has a range of ±24gs and can detect linear and angular accelerations in the three axes. This one was included because the previous accelerometer does not have a high-quality ratio and this one can make more precise lectures. The connections and component’s images can be seen below.
This is a long-range modem that provides ultra-long range spectrum communication and high interference immunity. There are different versions of this technology and its use has started to grow during the last two years, as it is some new technology. This LoRa Module has been included with a 433 MHz rubber duck antenna as it provides the best functionalities within the smallest space available.
3rd Ignition Circuit
Due to the needs to ignite three systems during the rocket’s flight, an additional ignition circuit was added, to ignite the second stage, the drogue parachute and the main parachute.
Board design of the PCB
Once we had the schematics finished, the board was designed following the same procedure as the previous boards. In this case the manufacturer was changed and a ground plane was added to the board. As this board is meant to be inside the rocket’s body and not inside the nosecone as the previous versions, it was made wider and shorter to fit the dimensions.
Fabrication process of the board