Structural Design
During mechanical construction of CanSat one must always take into consideration the mass
budget and the size of the CanSat. In most of the competitions you need to launch your CanSat from
10-15 (?) cm diameter rockets. In addition to that the mechanical structure of the CanSat must provide
an adequate space to contain the vulnerable electronic components. The design should protect it from
shocks by absorbing some of the energy that is generated during launch, release and parachute
deployment and landing.
The CanSat must have a mass of no more than 1000 g; considering its relatively low weight and
the small distance it will possibly fall, a wide range of material could be considered as appropriate to
fulfil the requirements, plastics and many different metals would be suitable. 350 ml or 500 ml volume
can may be used or you can manufacture your own design cansat from different light-weight metal or
composite materials such as glass fabric, carbon composit or alumininum. Aluminium or aluminium
alloys provide the rigid structure desired while being light-weight, non-brittle commonly available and
cheap.
Fig.1.Cansat made of carbon composite
For a CanSat there is no need for thermal insulation if you are not going to send the CanSat to an
altitude of more than 1000 m. The temperature will not drop more than 6-7 degrees compare to ground
temperature. For higher altitudes, such as she temperature in the stratosphere (216 ◦K) is significantly
lower than the temperature on ground. A CanSat that will be sent to such an altitude will be facing low
temperature condition which may threaten sensors to work properly. In order for this CanSat to be
successful, it must ensure that the electronic components (which are designed to operate at around sea
level temperatures) are not damaged and operate as long as possible. This will be achieved by
insulating the can to slow the temperature loss.
For the electronics, the PCB board should not be in direct contact with the outer surface fo the
CanSat. Applying soft materials, such as foam or some kind of insulating material, on the edges of the
frame holding the PCB boards, the shock will be more dispersed. The space remaining will contain
sensors and the batteries. The sensors will need to be arranged so that they can still take data. The
batteries can be firmly connected to foam and supported by CanSat walls preventing from moving.
For the effective use of the instrumentation, they need to be positioned where they can act
correctly. This requires careful consideration of safety, operating temperatures and other
environmental factors.
The pressure sensor has a minimum operating temperature of aronud 233°K . This sensor requires
access to the outside environment to take true readings of atmospheric pressure. The temperature
sensors will operate correctly until 233°K, then the readings are no longer reliable but the sensor will
not be damaged. The radio transmitter has a minimum operating temperature of 253 ° K. If the
temperature inside the probe is allowed to drop below ~253°K the signal will be affected or
interrupted. In this case the thermal insulator will play a major role, delaying cooling as much as
possible.
After CanSat construction some simple temperature and shock resistance test can be performed
on it. The results of these tests can then be used to determine whether the design was sufficient CanSat
structure. CanSat also should be tested in windy, stormy and icy conditions.
Fig.1.Wing Loading Test for a Fixed wing CanSat
For different types of CanSats you need appropriate designs always taking into account mass
budget and size. Especially for come back competitons you may use paragliding, rover back or fixed
wing types of CanSat. Paragliding CanSat requires direction and control mechanism. The direction in
heavy weather may not support the forces of the paraglide properly and the cansat may stall or drifted
away. For a rower back you should take into account the rower mechanism, obstacle avoidance system
and control in 2D condition. However, for a fixed wing CanSat you must control the CanSat in 3D.
Since you have limited space in the rocket your design must consider wing folding, tail and if there
exist engine propeller. The concept of the design must aim to improve performance, weight,
strenght and simplicity.
Fig.2.Rover back cansat with paraglider inside a rocket.
For a Mechanical design you should include drawings of the structure and component layout and
a list of materials and component selections. The mass budget shall include allocation of masses to the
various subsystems and/or components in a tabular form.
Access to the electrical components is an important design consideration. During the development
and testing phase of the CanSat, the battery, circuit boards and the transceiver will be removed and
replaced several times. Easy access to these components will save a significant amount of time over
the entire development and launch phase. In short, it is necessary to have a structure that is light,
strong, versatile, and easy to disassemble.