The North Medford Black Tornado (Secondary) Payload Design.
We have designed a payload container that allows multiple Common and Secondary payloads to mixed and matched into different launch systems. This design enables existing Common payloads to be used without change. The one exception is the Iridium Modem container, which we have rebuilt to work with our common framework.
As shown below, the design consists of a 7.75” diameter Lexan sheet mounted on top of 1” Foamular board. Electronic components are mounted onto a custom 3D printed support structure, which is secured to the Lexan sheet using a Velco strap. Separation between payloads layers is achieved using LEGO bricks, which provide strength, while also at the same time supporting variable spacing between layers. The Secondary payload in the figure below supports a GPS, external temperature sensor and an altitude-triggered buzzer.
The Secondary payload shown below supports an Adafruit 9 DOF IMU and a Sparkfun BMP180 Barometer. It also shows our approach to powering the system. The battery is a PKCELL 3.7V 6600 mAh battery. This battery is the same model at that used in the Main payloads. An Adafruit 500mA Powerboost module is used to increase the 3.7V battery output to 5.2V for powering the Arduino and sensor boards. The Powerboost module enables the battery to be charged in place. The power switch on the board is connected to the enable pin on the Powerboost module and is used to switch the system on and off. A custom built 3D printed support allows access to the power switch from outside of the
The power system described above can power multiple payloads. In the image below two payloads are linked together and powered by a single battery and power switch.
The Secondary payload shown below supports Vernier UVA, UVB and Radiation sensors. The radiation sensor counts alpha, beta and gamma particles. We plan to add an Ozone sensor to this payload. The sensors are connected to an Arduino by a Sparkfun interface. The same system as that described earlier is used to power the payload.
The Secondary payload shown below supports various models of cameras that can be configured to point upwards, downwards or sideways. Custom-built 3D brackets are used to support cameras in these various configurations. A Lexan sheet is act as a barrier between the inside of the payload and the exterior environment.
Rings cut using a CNC router are used to create the container for the payloads. Rings can be added or deleted based on the height of the payloads. We will not glue the rings together until the complete system is assembled. In general, each payload box consists of two halves that will be taped together just before launch. Shown below are the top and bottom halves of a container.
The complete container is shown below. The top ring is also supported by the Lego bricks of the top payload, which prevents the payloads from moving during flight. The image also shows the external buzzer and temperature sensor, which still need to be secured in place.
The image below shows the new configuration of the Iridium modem. We still need to add a Lexan support sheet and a switch. Adding a switch eliminates the need to plug and unplug the battery (except when charging) to power the system and enables the payload to be activated from outside of the container.