At UKZN’s annual Mechanical Engineering Open Day, students Ms Sarisha Harrylal, Mr Langelihle Majola and Mr Yashik Singh, supervised by Dr Michael Brooks, collaborated on the design of a roll control system (RCS) and the payload fairing, including attachment and separation mechanisms.
These are two of the many systems required for the development of a commercial launch vehicle (CLV), a rocket that places microsatellites into orbit. South Africa currently has no CLVs of its own, and the design of a two-stage South African rocket to perform this function forms part of the UKZN Aerospace Systems Research Group’s (ASReG) projects.
‘The RCS forms part a larger system that ensures that the planned trajectory of the rocket’s upper stage is maintained,’ explained team leader Harrylal. ‘The RCS is capable of spinning the vehicle up and correcting its angular position to ensure that the rocket stays on course.’
The group developed a gas delivery system that produces pulsed nitrogen jets and that can perform some of these manoeuvres in a ground-test environment. They also designed a fairing, the topmost part of the vehicle that protects the satellite payload and reduces drag during the launch of the vehicle. A non-destructive mechanism was developed to jettison the CLV when it reaches the correct altitude and releases the satellite into orbit.
The students achieved their goal by designing and manufacturing a test rig with a half-scale version of the CLV upper stage, enabling ASReG to test these systems in a laboratory environment. The test rig allows for different spin control laws, nozzle designs and payload separation mechanisms to be tested, fine-tuned and perfected, and can be spun by pulsing the RCS. Extensive testing before implementing the designs on the actual CLV in future guards against system errors that could result in failure once the CLV is launched.
Given that this is the first project of its kind in South Africa, the group had to grapple with a lack of experience and expertise relating to these systems in the country, taking them on a steep learning curve that involved extensive research to validate their design decisions. Sourcing suitable components was also a challenge due to the specialised application and its strict operating conditions.
‘The most rewarding thing was seeing our project take shape and perform as intended,’ said Harrylal.
Visitors to the Open Day viewed the rig with the half scale model and saw the RCS and the fairing separation mechanism in action.
Words: Christine Cuénod