The purpose of the Ausroc2.5 program is to launch a bi-propellant liquid fuelled rocket and filter down its technologies to larger projects such as the Ausroc3. UQ’s school of engineering was asked to design the Ausroc2.5’s recovery system which compose of the drogue and the main parachutes. The goal of the recovery system is to retrieve the rocket intact so that data can be collected and analysed and components can be reused. The landing speed of the vehicle is to be of no greater than 7m/s.
This thesis is the design of the drogue parachute recovery system for the Ausroc2.5 project. A fellow final year engineering student, Ian Dinh, will design the main parachute system. The primarily function of the drogue parachute is to slow down the rocket to a speed at which the main parachute can be deployed. The implementation of the drogue is to reduce the otherwise excessive shock exerted by the main parachute due to its larger canopy size.
Shock minimisation is also possible due to the sparse air density at apogee of the ballistic flight path.
The drogue system is design to be deployed at approximately 40km and follows the sequence of the nose cone ejection, tensioning of suspension lines and riser and then inflation of the drogue canopy. Ejection of the nose cone is to be activated by avionics system. At this moment, detail of the avionics signal is incomplete. It is important to note, that the avionic system is to be designed by students from other institutions and hence it is beyond the scope of this thesis.
The drogue canopy has a nominal diameter, Do, of 3.31m spanning 8.62m2. The vertical, horizontal, radial, skirt and vent tapes are to be made out of Kevlar material. This was dictated by the weight limitation set by ASRI.
Tuan A To 2004 Mechanical and Space Engineering
Computational Fluid Dynamics, CFD, analysis confirmed assumptions and parameters that were used based on “Knacke – Design manual of parachute recovery system” . Drag coefficient, Cd, values remain relatively constant at subsonic speed. CFD generated Cd values that were 23% lower than the values quoted by Knacke. This is because the drogue parachute was modeled on a 2-d plane and vertical tapes were neglected. This resulted in 44% porosity rather than the 29% that was designed. Most connecting components were chosen from readily available commercial stores. Those that weren’t available were analysed with STRAND7 and cross-referenced with theoretical calculations to safe guard against failure. Combined with the main parachute, 2-d flight simulation was carried out and concluded that the landing speed of the rocket is estimated to be 6.9 m/s which surpassed the criteria set by ASRI of less than 7m/s. Without the inclusion of the explosive cutters, total mass is about 5kg which is 2kg less than what ASRI specified.